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2204.14117 | A Comparative Study of Meter Detection Methods for Automated Infrastructure Inspection | In order to read meter values from a camera on an autonomous inspection robot with positional errors, it is necessary to detect meter regions from the image. In this study, we developed shape-based, texture-based, and background information-based methods as meter area detection techniques and compared their effectiveness for meters of different shapes and sizes. As a result, we confirmed that the background information-based method can detect the farthest meters regardless of the shape and number of meters, and can stably detect meters with a diameter of 40px. | [
"Computer Science Archive->cs.CV"
] | "2022-04-24T13:59:57" |
2305.19887 | The Markov chain embedding problem in a low jump frequency context | We consider the problem of finding the transition rates of a continuous-time homogeneous Markov chain under the empirical condition that the state changes at most once during a time interval of unit length. It is proven that this conditional embedding approach results in a unique intensity matrix for a transition matrix with non-zero diagonal entries. Hence, the presented conditional embedding approach has the merit to avoid the identification phase as well as regularization for the embedding problem. The resulting intensity matrix is compared to the approximation for the Markov generator found by Jarrow. | [
"Mathematics Archive->math.PR"
] | "2023-05-31T14:24:25" |
0910.5857 | Chaotic Transport and Chronology of Complex Asteroid Families | We present a transport model that describes the orbital diffusion of asteroids in chaotic regions of the 3-D space of proper elements. Our goal is to use a simple random-walk model to study the evolution and derive accurate age estimates for dynamically complex asteroid families. To this purpose, we first compute local diffusion coefficients, which characterize chaotic diffusion in proper eccentricity (e_p) and inclination (I_p), in a selected phase-space region. Then, a Monte-Carlo-type code is constructed and used to track the evolution of random walkers (i.e. asteroids), by coupling diffusion in (e_p,I_p) with a drift in proper semi-major axis (a_p) induced by the Yarkovsky/YORP thermal effects. We validate our model by applying it to the family of (490) Veritas, for which we recover previous estimates of its age (~8.3 Myr). Moreover, we show that the spreading of chaotic family members in proper elements space is well reproduced in our random-walk simulations. Finally, we apply our model to the family of (3556) Lixiaohua, which is much older than Veritas and thus much more affected by thermal forces. We find the age of the Lixiaohua family to be 155+/-36 Myr. | [
"Physics Archive->astro-ph->astro-ph.EP"
] | "2009-10-30T12:34:26" |
1801.10207 | FITing-Tree: A Data-aware Index Structure | Index structures are one of the most important tools that DBAs leverage to improve the performance of analytics and transactional workloads. However, building several indexes over large datasets can often become prohibitive and consume valuable system resources. In fact, a recent study showed that indexes created as part of the TPC-C benchmark can account for 55% of the total memory available in a modern DBMS. This overhead consumes valuable and expensive main memory, and limits the amount of space available to store new data or process existing data. In this paper, we present FITing-Tree, a novel form of a learned index which uses piece-wise linear functions with a bounded error specified at construction time. This error knob provides a tunable parameter that allows a DBA to FIT an index to a dataset and workload by being able to balance lookup performance and space consumption. To navigate this tradeoff, we provide a cost model that helps determine an appropriate error parameter given either (1) a lookup latency requirement (e.g., 500ns) or (2) a storage budget (e.g., 100MB). Using a variety of real-world datasets, we show that our index is able to provide performance that is comparable to full index structures while reducing the storage footprint by orders of magnitude. | [
"Computer Science Archive->cs.DB"
] | "2018-01-30T20:22:53" |
0803.0849 | The Universal Cardinal Ordering of Fixed Points | We present the theorem which determines, by a permutation, the cardinal ordering of fixed points for any orbit of a period doubling cascade. The inverse permutation generates the orbit and the symbolic sequence of the orbit is obtained as a corollary. The problem present in the symbolic sequences is solved. There, repeated symbols appear, for example, the R (right), which cannot be distinguished among them as it is not known which R is the rightmost of them all. Therefore, there is a lack of information about the dynamical system. Interestingly enough, it is important to point that this theorem needs no previous information about any other orbit. | [
"Physics Archive->nlin->nlin.CD"
] | "2008-03-06T12:55:48" |
2106.10546 | Mapping the hidden magnetic field of the quiet Sun | The Sun is the only star where we can resolve the intricate magnetism that all convective stars harbor. Yet, more than 99% of its visible surface along the solar cycle (the so-called quiet Sun) is filled with a tangled, unresolved magnetism. These "hidden" fields are thought to store enough magnetic energy to play a role in the heating of the Sun's outer atmosphere, but its field strength is still not constrained. Previous investigations based on the Hanle effect in atomic lines claim a strong magnetization of about 100 G, while the same effect in molecules show a factor of 10 weaker fields. The discrepancy disappears if the magnetic field strength of the hidden is not homogeneous in the solar surface. In this letter, we prove using magnetohydrodynamical simulations that it is possible to infer the average field strength of the hidden quiet Sun magnetic fields using multi-line inversions of intensity profiles in the Zeeman regime. Using this technique with 15 spectral lines in the 1.5 $\mu$m spectral range, we reveal that the spatial distribution of the hidden field is strongly correlated with convection motions, and that the average magnetization is about 46 G. Reconciling our findings with the Hanle ones is not obvious and will require future work on both sides, since it implies an increase of the field strength with height, something that is physically questionable. | [
"Physics Archive->astro-ph->astro-ph.SR"
] | "2021-06-19T18:22:00" |
1209.3926 | Interaction of atomic quantum gases with a single carbon nanotube | We study inelastic processes in the hybrid quantum system constituted by a carbon nanotube (CNT) in contact with an ultracold quantum gas, such as a cloud of thermal atoms or a Bose-Einstein condensate (BEC). We present a parameter-free ab-initio approach for the loss rate based on the underlying scattering process, considering the two-dimensional character of the system as well as the exact Casimir-Polder potential. The predicted loss rates are in perfect agreement with recent experimental results, obtained both for a thermal cloud of rubidium atoms and for a BEC. For the trap loss of a thermal cloud, we find that retardation effects become important and contribute significantly, which emphasises the crucial role of the exact interaction potential. | [
"Physics Archive->physics->physics.atom-ph"
] | "2012-09-18T12:34:13" |
1812.10157 | Motion Selective Prediction for Video Frame Synthesis | Existing conditional video prediction approaches train a network from large databases and generalize to previously unseen data. We take the opposite stance, and introduce a model that learns from the first frames of a given video and extends its content and motion, to, eg, double its length. To this end, we propose a dual network that can use in a flexible way both dynamic and static convolutional motion kernels, to predict future frames. The construct of our model gives us the the means to efficiently analyze its functioning and interpret its output. We demonstrate experimentally the robustness of our approach on challenging videos in-the-wild and show that it is competitive wrt related baselines. | [
"Computer Science Archive->cs.CV",
"Computer Science Archive->cs.LG"
] | "2018-12-25T19:15:29" |
2207.05689 | The Rate and Spatial Distribution of Novae in M31 as Determined by a Twenty-Year Survey | A long-term (1995-2016) survey for novae in the nearby Andromeda galaxy (M31) was conducted as part of the Research-Based Science Education initiative. During the course of the survey 180 nights of observation were completed at Kitt Peak, Arizona. A total of 262 novae were either discovered or confirmed, 40 of which have not been previously reported. Of these, 203 novae form a spatially-complete sample detected by the KPNO/WIYN 0.9-m telescope within a $20'\times20'$ field centered on the nucleus of M31. An additional 50 novae are part of a spatially-complete sample detected by the KPNO 4-m telescope within a larger $36'\times36'$ field. Consistent with previous studies, it is found that the spatial distribution of novae in both surveys follows the bulge light of M31 somewhat more closely than the overall background light of the galaxy. After correcting for the limiting magnitude and the spatial and temporal coverage of the surveys, a final nova rate in M31 is found to be $R=40^{+5}_{-4}$ yr$^{-1}$, which is considerably lower than recent estimates. When normalized to the $K$-band luminosity of M31, this value yields a luminosity-specific nova rate, $\nu_K = 3.3\pm0.4$ yr$^{-1} [10^{10} L_{\odot,K}]^{-1}$. By scaling the M31 nova rate using the relative infrared luminosities of M31 and our Galaxy, a nova rate of $R_\mathrm{G}=28^{+5}_{-4}$ is found for the Milky Way. | [
"Physics Archive->astro-ph->astro-ph.GA",
"Physics Archive->astro-ph->astro-ph.SR"
] | "2022-07-12T17:10:19" |
1912.10902 | Upper and Lower Bounds for Large Scale Multistage Stochastic Optimization Problems: Application to Microgrid Management | We consider a microgrid where different prosumers exchange energy altogether by the edges of a given network. Each prosumer is located to a node of the network and encompasses energy consumption, energy production and storage capacities (battery, electrical hot water tank). The problem is coupled both in time and in space, so that a direct resolution of the problem for large microgrids is out of reach (curse of dimensionality). By affecting price or resources to each node in the network and resolving each nodal sub-problem independently by Dynamic Programming, we provide decomposition algorithms that allow to compute a set of decomposed local value functions in a parallel manner. By summing the local value functions together, we are able, on the one hand, to obtain upper and lower bounds for the optimal value of the problem, and, on the other hand, to design global admissible policies for the original system. Numerical experiments are conducted on microgrids of different size, derived from data given by the research and development centre Efficacity, dedicated to urban energy transition. These experiments show that the decomposition algorithms give better results than the standard SDDP method, both in terms of bounds and policy values. Moreover, the decomposition methods are much faster than the SDDP method in terms of computation time, thus allowing to tackle problem instances incorporating more than 60 state variables in a Dynamic Programming framework. | [
"Mathematics Archive->math.OC"
] | "2019-12-23T15:04:46" |
1312.7235 | Rotating and infalling motion around the high-mass young stellar object Cepheus A-HW2 observed with the methanol maser at 6.7 GHz | We have measured the internal proper motions of the 6.7 GHz methanol masers associated with Cepheus A (Cep A) HW2 using Very Long Baseline Interferometery (VLBI) observations. We conducted three epochs of VLBI monitoring observations of the 6.7 GHz methanol masers in Cep A-HW2 with the Japanese VLBI Network (JVN) over the period between 2006-2008. In 2006, we were able to use phase-referencing to measure the absolute coordinates of the maser emission with an accuracy of a few milliarcseconds. We compared the maser distribution with other molecular line observations that trace the rotating disk. We measured the internal proper motions for 29 methanol maser spots, of which 19 were identified at all three epochs and the remaining ten at only two epochs. The magnitude of proper motions ranged from 0.2 to 7.4 km/s, with an average of 3.1 km/s. Although there are large uncertainties in the observed internal proper motions of the methanol maser spots in Cep A, they are well fitted by a disk that includes both rotation and infall velocity components. The derived rotation and infall velocities at the disk radius of 680 au are 0.5 +- 0.7 and 1.8 +- 0.7 km/s, respectively. Assuming that the modeled disk motion accurately represents the accretion disk around the Cep A-HW2 high-mass YSO, we estimated the mass infall rate to be 3 x 10^{-4} n_8 Msun/yr (n_8 is the gas volume density in units of 10^{8} cm^{-3}). The combination of the estimated mass infall rate and the magnitude of the fitted infall velocity suggests that Cep A-HW2 is at an evolutionary phase of active gas accretion from the disk onto the central high-mass YSO. The infall momentum rate is estimated to be 5 x 10^{-4} n_8 Msun/yr km/s, which is larger than the estimated stellar radiation pressure of the HW2 object, supporting the hypothesis that this object is in an active gas accretion phase. | [
"Physics Archive->astro-ph->astro-ph.GA",
"Physics Archive->astro-ph->astro-ph.SR"
] | "2013-12-27T10:13:50" |
1305.4058 | Limit theorems for continuous time random walks with continuous paths | The continuous time random walks (CTRWs) are typically defned in the way that their trajectories are discontinuous step fuctions. This may be a unwellcome feature from the point of view of application of theese processes to model certain physical phenomena. In this article we propose alternative definition of continuous time random walks with continuous trajectories. We also give the functional limit theorem for sequence of such random walks. This result requires the use of strong Skorohod M1 topology instead of Skorohod J1 topology, which is usually used in limit theorems for ordinary CTRW processes. | [
"Mathematics Archive->math.PR"
] | "2013-05-17T12:22:05" |
1311.0979 | Structure, elastic and dynamical properties of KN$_3$ and RbN$_3$: A van der Waals density functional study | We report a detailed first principles study on the structural, elastic, vibrational and thermodynamic properties of layered structure energetic alkali metal azides KN$_3$ and RbN$_3$. All the calculations were carried out by means of plane wave pseudopotential method with and without including van der Waals interactions. The calculated ground state structural properties are improved to a greater extent by the inclusion of dispersion corrections, implies that the van der Waals interactions play a major role on the physical properties of these systems. The elastic constants and the related bulk mechanical properties for the tetragonal KN$_3$ and RbN$_3$ have been calculated using both the methods and found that the compounds are mechanically stable systems. The magnitude of the calculated elastic constants increases in the order RbN$_3$ $<$ KN$_3$ implying higher elastic stiffness for KN$_3$, the fact also confirmed by the higher values of bulk, shear and Young's moduli of KN$_3$ than RbN$_3$. Moreover, the calculated elastic constants follows the inequality C$_{33}$ $<$ C$_{11}$ which indicates the presence of more number of intermolecular interactions along a-axis over c-axis of the azide lattices. A correlation has been proposed to relate the calculated elastic constants to the decomposition phenomena for the metal azides. The experimentally reported vibrational frequencies at the gamma point were exactly reproduced by the present calculations. In addition, we also present the thermodynamic properties such as heat capacity which compares well with the experiment. | [
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | "2013-11-05T07:14:41" |
1408.3180 | On the Jordan-Kinderlehrer-Otto scheme | In this paper, we prove that the Jordan-Kinderlehrer-Otto scheme for a family of linear parabolic equations on the flat torus converges uniformly in space. | [
"Mathematics Archive->math.AP"
] | "2014-08-14T02:01:51" |
1706.00749 | Electromagnetic vacuum fluctuations around a cosmic string in de Sitter spacetime | The electromagnetic field correlators are evaluated around a cosmic string in background of $(D+1)$-dimensional dS spacetime assuming that the field is prepared in the Bunch-Davies vacuum state. The correlators are presented in the decomposed form where the string-induced topological parts are explicitly extracted. With this decomposition, the renormalization of the local vacuum expectation values (VEVs) in the coincidence limit is reduced to the one for dS spacetime in the absence of the cosmic string. The VEVs of the squared electric and magnetic fields, and of the vacuum energy density are investigated. Near the string they are dominated by the topological contributions and the effects induced by the background gravitational field are small. In this region, the leading terms in the topological contributions are obtained from the corresponding VEVs for a string on the Minkowski bulk multiplying by the conformal factor. At distances from the string larger than the curvature radius of the background geometry, the pure dS parts in the VEVs dominate. In this region, for spatial dimensions $D>3$, the influence of the gravitational field on the topological contributions is crucial and the corresponding behavior is essentially different from that for a cosmic string on the Minkowski bulk. There are well-motivated inflationary models which produce cosmic strings. We argue that, as a consequence of the quantum-to-classical transition of super-Hubble electromagnetic fluctuations during inflation, in the postinflationary era these strings will be surrounded by large scale stochastic magnetic fields. These fields could be among the distinctive features of the cosmic strings produced during the inflation and also of the corresponding inflationary models. | [
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th",
"Physics Archive->quant-ph"
] | "2017-06-02T16:48:12" |
1311.5743 | Frenkel electron and a spinning body in a curved background | We develop a variational formulation of a particle with spin in a curved space-time background. The model is based on a singular Lagrangian which provides equations of motion, a fixed value of spin and Frenkel condition on spin-tensor. Comparing our equations with those of Papapetrou we conclude that the Frenkel electron in a gravitational field has the same behavior as a rotating body in the pole-dipole and leading-spin approximation. Due to constraints presented in the formulation, position space is endowed with a noncommutative structure induced by the spin of the particle. Therefore, the model provides a physically interesting example of a noncommutative particle in a curved background. | [
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | "2013-11-22T13:07:36" |
2005.08609 | On the Hardness of Red-Blue Pebble Games | Red-blue pebble games model the computation cost of a two-level memory hierarchy. We present various hardness results in different red-blue pebbling variants, with a focus on the oneshot model. We first study the relationship between previously introduced red-blue pebble models (base, oneshot, nodel). We also analyze a new variant (compcost) to obtain a more realistic model of computation. We then prove that red-blue pebbling is NP-hard in all of these model variants. Furthermore, we show that in the oneshot model, a $\delta$-approximation algorithm for $\delta<2$ is only possible if the unique games conjecture is false. Finally, we show that greedy algorithms are not good candidates for approximation, since they can return significantly worse solutions than the optimum. | [
"Computer Science Archive->cs.CC"
] | "2020-05-18T11:44:59" |
1602.07434 | Absorption probabilities associated with spin-3/2 particles near $N$-dimensional Schwarzschild black holes | In June 2015 the Large Hadron Collider was able to produce collisions with an energy of 13TeV, where collisions at these energy levels may allow for the formation of higher dimensional black holes. In order to detect these higher dimensional black holes we require an understanding of their emission spectra. One way of determining this is by looking at the absorption probabilities associated with the black hole. In this proceedings we will look at the absorption probability for spin-3/2 particles near $N$-dimensional Schwarzschild black holes. We will show how the Unruh method is used to determine these probabilities for low energy particles. We then use the Wentzel-Kramers-Brillouin approximation in order to determine these absorption probabilities for the entire possible energy range. | [
"Physics Archive->gr-qc"
] | "2016-02-24T08:54:54" |
1902.09198 | On rational homotopy and minimal models | We prove a result that enables us to calculate the rational homotopy of a wide class of spaces by the theory of minimal models. | [
"Mathematics Archive->math.AT"
] | "2019-02-25T11:20:52" |
2207.13711 | High frequency radio imaging of 3CR 403.1 with the Sardinia Radio Telescope | We present multifrequency observations of the radio source 3CR 403.1, a nearby (z=0.055), extended ($\sim$0.5 Mpc) radio galaxy hosted in a small galaxy group. Using new high frequency radio observations from the Sardinia Radio Telescope (SRT), augmented with archival low frequency radio observations, we investigated radio spectral and polarimetric properties of 3CR 403.1. From the MHz-to-GHz spectral analysis, we computed the equipartition magnetic field in the lobes to be B$_{eq}$=2.4~$\mu$G and the age of the source to be $\sim$100 Myr. From the spectral analysis of the diffuse X-ray emission we measured the temperature and density of the intracluster medium (ICM). From the SRT observations, we discovered two regions where the radio flux density is below the background value. We computed the Comptonization parameter both from the radio and from the X-ray observations to test if the Sunyaev-Zel'dovich effect is occurring here and found a significant tension between the two estimates. If the negative signal is considered as real, then we speculate that the discrepancy between the two values could be partially caused by the presence of a non-thermal bath of mildly relativistic ghost electrons. From the polarimetric radio images, we find a net asymmetry of the Faraday rotation between the two prominent extended structures of 3CR 403.1, and constrain the magnetic field strength in the ICM to be 1.8-3.5 $\mu$G. The position of 3CR 403.1 in the magnetic field-gas density plane is consistent with the trend reported in the literature between central magnetic field and central gas density. | [
"Physics Archive->astro-ph->astro-ph.GA",
"Physics Archive->astro-ph->astro-ph.HE"
] | "2022-07-27T18:00:01" |
2211.17044 | On Bernoulli trials with unequal harmonic success probabilities | A Bernoulli scheme with unequal harmonic success probabilities is investigated, together with some of its natural extensions. The study includes the number of successes over some time window, the times to (between) successive successes and the time to the first success. Large sample asymptotics, statistical parameter estimation, and relations to Sibuya distributions and Yule-Simon distributions are discussed. This toy model is relevant in several applications including reliability, species sampling problems, record values breaking and random walks with disasters. | [
"Mathematics Archive->math.PR"
] | "2022-11-30T14:45:09" |
2011.14764 | Binary Classification: Counterbalancing Class Imbalance by Applying Regression Models in Combination with One-Sided Label Shifts | In many real-world pattern recognition scenarios, such as in medical applications, the corresponding classification tasks can be of an imbalanced nature. In the current study, we focus on binary, imbalanced classification tasks, i.e.~binary classification tasks in which one of the two classes is under-represented (minority class) in comparison to the other class (majority class). In the literature, many different approaches have been proposed, such as under- or oversampling, to counter class imbalance. In the current work, we introduce a novel method, which addresses the issues of class imbalance. To this end, we first transfer the binary classification task to an equivalent regression task. Subsequently, we generate a set of negative and positive target labels, such that the corresponding regression task becomes balanced, with respect to the redefined target label set. We evaluate our approach on a number of publicly available data sets in combination with Support Vector Machines. Moreover, we compare our proposed method to one of the most popular oversampling techniques (SMOTE). Based on the detailed discussion of the presented outcomes of our experimental evaluation, we provide promising ideas for future research directions. | [
"Computer Science Archive->cs.LG"
] | "2020-11-30T13:24:47" |
1804.02177 | Coupled Wire Model of Z4 Orbifold Quantum Hall States | We introduce a coupled wire model for a sequence of non-Abelian quantum Hall states that generalize the Z4 parafermion Read Rezayi state. The Z4 orbifold quantum Hall states occur at filling factors \nu = 2/(2m-p) for odd integers $m$ and $p$, and have a topological order with a neutral sector characterized by the orbifold conformal field theory with central charge $c=1$ at radius $R=\sqrt{p/2}$. When $p=1$ the state is Abelian. The state with $p=3$ is the $Z_4$ Read Rezayi state, and the series of $p\ge 3$ defines a sequence of non-Abelian states that resembles the Laughlin sequence. Our model is based on clustering of electrons in groups of four, and is formulated as a two fluid model in which each wire exhibits two phases: a weak clustered phase, where charge $e$ electrons coexist with charge $4e$ bosons and a strong clustered phase where the electrons are strongly bound in groups of 4. The transition between these two phases on a wire is mapped to the critical point of the 4 state clock model, which in turn is described by the orbifold conformal field theory. For an array of wires coupled in the presence of a perpendicular magnetic field, strongly clustered wires form a charge $4e$ bosonic Laughlin state with a chiral charge mode at the edge, but no neutral mode and a gap for single electrons. Coupled wires near the critical state form quantum Hall states with a gapless neutral mode described by the orbifold theory. The coupled wire approach allows us to employ the Abelian bosonization technique to fully analyze the physics of single wire, and then to extract most topological properties of the resulting non-Abelian quantum Hall states. These include the list of quasiparticles, their fusion rules, the correspondence between bulk quasiparticles and edge topological sectors, and most of the phases associated with quasiparticles winding one another. | [
"Physics Archive->cond-mat->cond-mat.str-el",
"Physics Archive->hep->hep-th"
] | "2018-04-06T09:39:15" |
2004.03115 | How moving cracks in brittle solids choose their path | While we fundamentally understand the dynamics of 'simple' cracks propagating in brittle solids within perfect (homogeneous) materials, we do not understand how paths of moving cracks are determined. We experimentally study strongly perturbed cracks that propagate between 10-95\% of their limiting velocity within a brittle material. These cracks are deflected by either interaction with sparsely implanted defects or via an intrinsic oscillatory instability in defect-free media. Dense, high-speed measurements of the strain fields surrounding the crack tips reveal that crack paths are governed by the direction of maximal strain energy density. This fundamentally important result may be utilized to either direct or guide running cracks. | [
"Physics Archive->cond-mat->cond-mat.soft"
] | "2020-04-07T04:08:54" |
1201.3331 | Electrostatic field acceleration of laser-driven ion bunch by using double layer thin foils | Monoenergetic ion bunch generation and acceleration from double layer thin foil target irradiated by intense linearly polarized (LP) laser pulse is investigated using two-dimensional (2D) particle-in-cell (PIC) simulations. The low-Z ions in the front layer of the target are accelerated by the laser-driven hot electrons and penetrate through the high-Z ion layer to generate a quasi-monoenergetic ion bunch, and this bunch will continue to be accelerated by the quasi-stable electrostatic sheath field which is formed by the immobile high-Z ions and the hot electrons. This mechanism offers possibility to generate monoenergetic ion bunch without ultrahigh-contrast and ultrahigh gradient laser pulses in beam generation experiments, which is confirmed by our simulations. | [
"Physics Archive->physics->physics.plasm-ph"
] | "2012-01-16T18:31:02" |
2210.05645 | Zero Energy Self-Similar Solutions Describing Singularity Formation In The Nonlinear Schrodinger Equation In Dimension N=3 | In dimension N=3 the cubic nonlinear Schrodinger equation has solutions which become singular, i.e. at a spatial point they blow up to infinity in finite time. In 1972 Zakharov famously investigated finite time singularity formation in the cubic nonlinear Schrodinger equation as a model for spatial collapse of Langmuir waves in plasma, the most abundant form of observed matter in the universe. Zakharov assumed that (NLS) blow up of solutions is self-similar and radially symmetric, and that singularity formation can be modeled by a solution of an associated self-similar, complex ordinary differential equation~(ODE). A parameter a>0 appears in the ODE, and the dependent variable, Q, satisfies (Q(0),Q'(0))=(Q_{0},0), where Q(0)>0. A fundamentally important step towards putting the Zakharov model on a firm mathematical footing is to prove, when N=3, whether values a>0 and Q_{0}>0 exist such that Q also satisfies the physically important `zero-energy' integral constraint. Since 1972 this has remained an open problem. Here, we resolve this issue by proving that for every a>0 and Q(0)>0, Q satisfies the the `zero-energy' integral constraint. | [
"Mathematics Archive->math.AP",
"Mathematics Archive->math.CA"
] | "2022-10-02T17:23:18" |
quant-ph/9803071 | Vibrational Decoherence in Ion-Trap Quantum Computers | Decoherence is studied in an attractive proposal for an actual implementation of a quantum computer based on trapped ions. Emphasis is placed on the decoherence arising from the vibrational motion of the ions, which is compared with that due to spontaneous emission from excited states of the ions. The calculation is made tractable by exploiting the vast difference in time scales between the vibrational excitations and the intra-ionic electronic excitations. Since the latter are several orders of magnitude faster, an adiabatic approximation is used to integrate them out and find the inclusive probability P(t) for the elec- tronic state of the ions to evolve as it would in the absence of vibrational coupling, and the ions to evolve into any state whatsoever. The decoherence time is found at zero temperature and for any number of ions N in the computer. Comparison is made with the spontaneous emission decoherence, and the implications for how trap voltages and other parameters should be scaled with N are discussed. | [
"Physics Archive->quant-ph"
] | "1998-03-25T19:35:49" |
0712.4099 | Digital Ecosystems: Optimisation by a Distributed Intelligence | Can intelligence optimise Digital Ecosystems? How could a distributed intelligence interact with the ecosystem dynamics? Can the software components that are part of genetic selection be intelligent in themselves, as in an adaptive technology? We consider the effect of a distributed intelligence mechanism on the evolutionary and ecological dynamics of our Digital Ecosystem, which is the digital counterpart of a biological ecosystem for evolving software services in a distributed network. We investigate Neural Networks and Support Vector Machine for the learning based pattern recognition functionality of our distributed intelligence. Simulation results imply that the Digital Ecosystem performs better with the application of a distributed intelligence, marginally more effectively when powered by Support Vector Machine than Neural Networks, and suggest that it can contribute to optimising the operation of our Digital Ecosystem. | [
"Computer Science Archive->cs.NE"
] | "2007-12-26T04:13:20" |
math/0512344 | Smooth Optimization with Approximate Gradient | We show that the optimal complexity of Nesterov's smooth first-order optimization algorithm is preserved when the gradient is only computed up to a small, uniformly bounded error. In applications of this method to semidefinite programs, this means in some instances computing only a few leading eigenvalues of the current iterate instead of a full matrix exponential, which significantly reduces the method's computational cost. This also allows sparse problems to be solved efficiently using sparse maximum eigenvalue packages. | [
"Mathematics Archive->math.OC"
] | "2005-12-14T21:12:19" |
1301.6102 | Medium-Induced QCD Cascade: Democratic Branching and Wave Turbulence | We study the average properties of the gluon cascade generated by an energetic parton propagating through a quark-gluon plasma. We focus on the soft, medium-induced emissions which control the energy transport at large angles with respect to the leading parton. We show that the effect of multiple branchings is important. In contrast with what happens in a usual QCD cascade in vacuum, medium-induced branchings are quasidemocratic, with offspring gluons carrying sizable fractions of the energy of their parent gluon. This results in an efficient mechanism for the transport of energy toward the medium, which is akin to wave turbulence with a scaling spectrum $\sim 1/\sqrt{\omega}$. We argue that the turbulent flow may be responsible for the excess energy carried by very soft quanta, as revealed by the analysis of the dijet asymmetry observed in Pb-Pb collisions at the LHC. | [
"Physics Archive->hep->hep-ph",
"Physics Archive->nucl->nucl-th"
] | "2013-01-25T17:36:09" |
1409.5316 | Explicit examples of Lipschitz, one-homogeneous solutions of log-singular planar elliptic systems | We give examples of systems of Partial Differential Equations that admit non-trivial, Lipschitz and one-homogeneous solutions in the form $u(R,\theta) = Rg(\theta)$, where $(R,\theta)$ are plane polar coordinates and $g: \mathbb{R}^{2} \to \mathbb{R}^{m}$, $m \geq 2$. The systems are singular in the sense that they arise as the Euler-Lagrange equations of the functionals $I(u) = \int_{B}W(x,\nabla u(x))\,dx$, where $D_{F}W(x,F)$ behaves like $\frac{1}{|x|}$ as $|x| \to 0$ and $W$ satisfies an ellipticity condition. Such solutions cannot exist when $|x|D_{F}W(x,F) \to 0$ as $|x| \to 0$, so the condition is optimal. The associated analysis exploits the well-known Fefferman-Stein duality. We also discuss conditions for the uniqueness of these one-homogeneous solutions and demonstrate that they are minimizers of certain variational functionals. | [
"Mathematics Archive->math.AP"
] | "2014-09-18T14:41:42" |
1212.6329 | Noncommutative Phase Spaces on Aristotle group | We realize noncommutative phase spaces as coadjoint orbits of extensions of the Aristotle group in a two-dimensional space. Through these constructions the momenta of the phase spaces do not commute due to the presence of a naturally introduced magnetic field. These cases correspond to the minimal coupling of the momentum with a magnetic potential. | [
"Mathematics Archive->math.MP",
"Physics Archive->math-ph"
] | "2012-12-27T09:03:40" |
2105.12997 | A unified explicit form for difference formulas for fractional and classical derivatives | A unified explicit form for difference formulas to approximate the fractional and classical derivatives is presented. The formula gives finite difference approximations for any classical derivatives with a desired order of accuracy at nodal point in the computational domain. It also gives Gr\"unwald type approximations for fractional derivatives with arbitrary order of approximation at any point. Thus, this explicit unifies approximations of both types of derivatives. Moreover, for classical derivatives, it provides various finite difference formulas such as forward, backward, central, staggered, compact, non-compact etc. Efficient computations of the coefficients of the difference formulas are also presented that lead to automating the solution process of differential equations with a given higher order accuracy. Some basic applications are presented to demonstrate the usefulness of this unified formulation. | [
"Computer Science Archive->cs.NA",
"Mathematics Archive->math.NA"
] | "2021-05-27T08:35:00" |
1910.08181 | Online Learning in Planar Pushing with Combined Prediction Model | Pushing is a useful robotic capability for positioning and reorienting objects. The ability to accurately predict the effect of pushes can enable efficient trajectory planning and complicated object manipulation. Physical prediction models for planar pushing have long been established, but their assumptions and requirements usually don't hold in most practical settings. Data-driven approaches can provide accurate predictions for offline data, but they often have generalizability issues. In this paper, we propose a combined prediction model and an online learning framework for planar push prediction. The combined model consists of a neural network module and analytical components with a low-dimensional parameter. We train the neural network offline using pre-collected pushing data. In online situations, the low-dimensional analytical parameter is learned directly from online pushes to quickly adapt to the new environments. We test our combined model and learning framework on real pushing experiments. Our experimental results show that our model is able to quickly adapt to new environments while achieving similar final prediction performance as that of pure neural network models. | [
"Computer Science Archive->cs.LG",
"Computer Science Archive->cs.RO"
] | "2019-10-17T21:43:56" |
2010.06031 | Dynamics and entropy of $\mathcal{S}$-graph shifts | $S$-gap shifts are a well-studied class of shift spaces, which has led to several proposed generalizations. This paper introduces a new class of shift spaces called $\mathcal{S}$-graph shifts whose essential structure is encoded in a novel way, as a finite directed graph with a set of natural numbers assigned to each vertex. $\mathcal{S}$-graph shifts contain $S$-gap shifts and their generalizations, as well as all vertex shifts and SFTs, as special cases, thereby providing a method to study these shift spaces in a uniform way. The main result in this paper is a formula for the entropy of any $\mathcal{S}$-graph shift, which, by specialization, resolves a problem proposed by Matson and Sattler. A second result establishes an explicit formula for the zeta functions of $\mathcal{S}$-graph shifts. Additionally, we show that every entropy value is obtained by uncountably many $\mathcal{S}$-graph shifts. | [
"Mathematics Archive->math.DS"
] | "2020-10-12T21:14:57" |
1501.04435 | Swift follow-up of IceCube triggers, and implications for the Advanced-LIGO era | Between 2011 March and 2014 August Swift responded to 20 triggers from the IceCube neutrino observatory, observing the IceCube 50% confidence error circle in X-rays, typically within 5 hours of the trigger. No confirmed counterpart has been detected. We describe the Swift follow up strategy and data analysis and present the results of the campaign. We discuss the challenges of distinguishing the X-ray counterpart to a neutrino trigger from serendipitous uncatalogued X-ray sources in the error circle, and consider the implications of our results for future strategies for multi-messenger astronomy, with particular reference to the follow up of gravitational wave triggers from the advanced-era detectors. | [
"Physics Archive->astro-ph->astro-ph.HE"
] | "2015-01-19T10:00:12" |
2111.00783 | An AI-powered Smart Routing Solution for Payment Systems | In the current era of digitization, online payment systems are attracting considerable interest. Improving the efficiency of a payment system is important since it has a substantial impact on revenues for businesses. A gateway is an integral component of a payment system through which every transaction is routed. In an online payment system, payment processors integrate with these gateways by means of various configurations such as pricing, methods, risk checks, etc. These configurations are called terminals. Each gateway can have multiple terminals associated with it. Routing a payment transaction through the best terminal is crucial to increase the probability of a payment transaction being successful. Machine learning (ML) and artificial intelligence (AI) techniques can be used to accurately predict the best terminals based on their previous performance and various payment-related attributes. We have devised a pipeline consisting of static and dynamic modules. The static module does the initial filtering of the terminals using static rules and a logistic regression model that predicts gateway downtimes. Subsequently, the dynamic module computes a lot of novel features based on success rate, payment attributes, time lag, etc. to model the terminal behaviour accurately. These features are updated using an adaptive time decay rate algorithm in real-time using a feedback loop and passed to a random forest classifier to predict the success probabilities for every terminal. This pipeline is currently in production at Razorpay routing millions of transactions through it in real-time and has given a 4-6\% improvement in success rate across all payment methods (credit card, debit card, UPI, net banking). This has made our payment system more resilient to performance drops, which has improved the user experience, instilled more trust in the merchants, and boosted the revenue of the business. | [
"Computer Science Archive->cs.AI"
] | "2021-11-01T09:33:02" |
2112.14022 | Towards Low Light Enhancement with RAW Images | In this paper, we make the first benchmark effort to elaborate on the superiority of using RAW images in the low light enhancement and develop a novel alternative route to utilize RAW images in a more flexible and practical way. Inspired by a full consideration on the typical image processing pipeline, we are inspired to develop a new evaluation framework, Factorized Enhancement Model (FEM), which decomposes the properties of RAW images into measurable factors and provides a tool for exploring how properties of RAW images affect the enhancement performance empirically. The empirical benchmark results show that the Linearity of data and Exposure Time recorded in meta-data play the most critical role, which brings distinct performance gains in various measures over the approaches taking the sRGB images as input. With the insights obtained from the benchmark results in mind, a RAW-guiding Exposure Enhancement Network (REENet) is developed, which makes trade-offs between the advantages and inaccessibility of RAW images in real applications in a way of using RAW images only in the training phase. REENet projects sRGB images into linear RAW domains to apply constraints with corresponding RAW images to reduce the difficulty of modeling training. After that, in the testing phase, our REENet does not rely on RAW images. Experimental results demonstrate not only the superiority of REENet to state-of-the-art sRGB-based methods and but also the effectiveness of the RAW guidance and all components. | [
"Computer Science Archive->cs.CV",
"Electrical Engineering and Systems Science Archive->eess.IV"
] | "2021-12-28T07:27:51" |
1507.06078 | Block algorithms with augmented Rayleigh-Ritz projections for large-scale eigenpair computation | Most iterative algorithms for eigenpair computation consist of two main steps: a subspace update (SU) step that generates bases for approximate eigenspaces, followed by a Rayleigh-Ritz (RR) projection step that extracts approximate eigenpairs. So far the predominant methodology for the SU step is based on Krylov subspaces that builds orthonormal bases piece by piece in a sequential manner. In this work, we investigate block methods in the SU step that allow a higher level of concurrency than what is reachable by Krylov subspace methods. To achieve a competitive speed, we propose an augmented Rayleigh-Ritz (ARR) procedure and analyze its rate of convergence under realistic conditions. Combining this ARR procedure with a set of polynomial accelerators, as well as utilizing a few other techniques such as continuation and deflation, we construct a block algorithm designed to reduce the number of RR steps and elevate concurrency in the SU steps. Extensive computational experiments are conducted in Matlab on a representative set of test problems to evaluate the performance of two variants of our algorithm in comparison to two well-established, high-quality eigensolvers ARPACK and FEAST. Numerical results, obtained on a many-core computer without explicit code parallelization, show that when computing a relatively large number of eigenpairs, the performance of our algorithms is competitive with, and frequently superior to, that of the two state-of-the-art eigensolvers. | [
"Mathematics Archive->math.NA"
] | "2015-07-22T07:12:25" |
hep-th/9406184 | Is Complex Probability Theory Consistent with Bell's Theorem? | Bayesian complex probability theory is shown to be consistent with Bell's theorem and with other recent limitations on local realistic theories which agree with the predictions of quantum mechanics. | [
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | "1994-06-28T16:30:21" |
hep-ph/0204097 | SO(10) a la Pati-Salam | We present rules for rewriting SO(10) tensor and spinor invariants in terms of invariants of its ``Pati-Salam'' maximal subgroup (SU(4)$\times \rm{SU(2)}_L\times \rm{SU(2)}_R)$ supplemented by the discrete symmetry called D parity. Explicit decompositions of quadratic and cubic invariants relevant to GUT model building are presented and the role of D parity in organizing the terms explained. Our rules provide a complete and explicit method for obtaining the "Clebsch-Gordon" Coefficients for $SO(10)\leftrightarrow G_{PS}$ in a notation appropriate for field theory models. We illustrate the usefulness our methods by calculating previously unavailable mass matrices and couplings of the $SU(2)_L$ doublets and $SU(3)_c $ triplets in the minimal Susy SO(10) GUT which are essential to specify the phenomenology of this model. We also present the bare effective potential for Baryon number violation in this model and show that it recives novel contributions from exchange of triplet Higgsinos contained the in ``neutrino mass'' Higgs submultiplets ${\bf{\bar{\Sigma}}}_{126}(10,1,3)$. This further tightens the emerging connection between neutrino mass and proton decay. | [
"Physics Archive->hep->hep-ph"
] | "2002-04-09T05:55:39" |
physics/0605028 | Effect of Magnetization Inhomogeneity on Magnetic Microtraps for Atoms | We report on the origin of fragmentation of ultracold atoms observed on a permanent magnetic film atom chip. A novel technique is used to characterize small spatial variations of the magnetic field near the film surface using radio frequency spectroscopy of the trapped atoms. Direct observations indicate the fragmentation is due to a corrugation of the magnetic potential caused by long range inhomogeneity in the film magnetization. A model which takes into account two-dimensional variations of the film magnetization is consistent with the observations. | [
"Physics Archive->physics->physics.atom-ph"
] | "2006-05-03T03:13:55" |
hep-ph/9404299 | New Supernova Constraints on active-sterile neutrino conversions | We consider active-sterile neutrino conversions in a supernova in the presence of random magnetic field domains. For large enough fields the magnetization of the medium may enhance the active to sterile neutrino conversion rates. Neglecting neutrino transition magnetic moments we show that for KeV neutrino mass squared differences these limits may overcome those that would apply in the isotropic case. | [
"Physics Archive->hep->hep-ph"
] | "1994-04-19T19:00:00" |
1806.10791 | Generalised Springer correspondence for Z/m-graded Lie algebras | Let $G$ be a simple simply connected complex algebraic group and let $\mathfrak{g}_*$ be a $\mathbf{Z}/m$-grading on its Lie algebra $\mathfrak{g}$. In a recent series of articles, G. Lusztig and Z. Yun, studied the classification of simple $G_0$-equivariant perverse sheaves on the nilpotent cone of $\mathfrak{g}_i$ for $i\in \mathbf{Z}/m$, where $G_0$ is the exponentiation of the degree zero piece $\mathfrak{g}_0$. They proved a decomposition of the equivariant derived category of $\ell$-adic sheaves on the nilpotent cone of $\mathfrak{g}_i$ into blocks, each generated by a certain cuspidal local system via {\itshape spiral inductions}. We prove a conjecture of them, which predicts the bijectivity of a map from 1) the set of simple perverse sheaves in a fixed block to 2) the set of simple modules of a block of a (trigonometric) degenerate double affine Hecke algebra (dDAHA). This is a dDAHA analogue of the Deligne--Langlands correspondence for affine Hecke algebras proven by Kazhdan--Lusztig. Our results generalise a previous work of E. Vasserot, where the perverse sheaves in the principal block were considered. | [
"Mathematics Archive->math.RT"
] | "2018-06-28T06:54:42" |
0801.0049 | Horizontal loops in Engel space | A simple proof is given of the following result first observed by J. Adachi: embedded circles tangent to the standard Engel structure on Euclidean 4-space are classified, up to isotopy via such embeddings, by their rotation number. | [
"Mathematics Archive->math.GT",
"Mathematics Archive->math.SG"
] | "2007-12-29T11:13:23" |
2309.01306 | A linearly convergent method for solving high-order proximal operator | Recently, various high-order methods have been developed to solve the convex optimization problem. The auxiliary problem of these methods shares the general form that is the same as the high-order proximal operator proposed by Nesterov. In this paper, we present a linearly convergent method to solve the high-order proximal operator based on the classical proximal operator. In addition, some experiments are performed to demonstrate the performance of the proposed method. | [
"Mathematics Archive->math.OC"
] | "2023-09-04T01:31:25" |
2211.15024 | The Conformal Laplacian and The Kazdan-Warner Problem: Zero First Eigenvalue Case | In this article, we first show that given a smooth function $ S $ either on closed manifolds $ (M, g) $ or compact manifolds $ (\bar{M}, g) $ with non-empty boundary, both for dimensions at least $ 3 $, the condition $ S \equiv 0 $, or $ S $ changes sign and $ \int_{M} S \dvol < 0 $ (with zero mean curvature if the boundary is not empty), is both the necessary and sufficient condition for prescribing scalar curvature problems within conformal class $ [g] $, provided that the first eigenvalue of the conformal Laplacian is zero. We then extend the same necessary and sufficient condition, in terms of prescribing Gauss curvature function and zero geodesic curvature, to compact Riemann surfaces with non-empty boundary, provided that the Euler characteristic is zero. These results are the first full extensions since the results of Kazdan and Warner \cite{KW2} on 2-dimensional torus, and of Escobar and Schoen \cite{ESS} on closed manifolds for dimensions $ 3 $ and $ 4 $. We then give results of prescribing nonzero scalar and mean curvature problems on $ (\bar{M}, g) $, still with zero first eigenvalue and dimensions at least $ 3 $. Analogously, results of prescribing Gauss and geodesic curvature problems on compact Riemann surfaces with boundary are given for zero Euler characteristic case. Lastly, we show a generalization of the Han-Li conjecture. Technically the key step for manifolds with dimensions at least $ 3 $ is to apply both the local variational methods, local Yamabe-type equations and a new version of the monotone iteration scheme. The key features include the smoothness of the upper solution, the technical difference between constant and non-constant prescribing scalar curvature functions, etc. | [
"Mathematics Archive->math.DG"
] | "2022-11-28T03:13:55" |
1507.06353 | ShakeMe: Key Generation From Shared Motion | Devices equipped with accelerometer sensors such as today's mobile devices can make use of motion to exchange information. A typical example for shared motion is shaking of two devices which are held together in one hand. Deriving a shared secret (key) from shared motion, e.g. for device pairing, is an obvious application for this. Only the keys need to be exchanged between the peers and neither the motion data nor the features extracted from it. This makes the pairing fast and easy. For this, each device generates an information signal (key) independently of each other and, in order to pair, they should be identical. The key is essentially derived by quantizing certain well discriminative features extracted from the accelerometer data after an implicit synchronization. In this paper, we aim at finding a small set of effective features which enable a significantly simpler quantization procedure than the prior art. Our tentative results with authentic accelerometer data show that this is possible with a competent accuracy ($76$%) and key strength (entropy approximately $15$ bits). | [
"Computer Science Archive->cs.CR"
] | "2015-07-22T22:51:08" |
1305.2188 | Photo-Met: a non-parametric method for estimating stellar metallicity from photometric observations | Getting spectra at good signal-to-noise ratios takes orders of magnitudes more time than photometric observations. Building on the technique developed for photometric redshift estimation of galaxies, we develop and demonstrate a non-parametric photometric method for estimating the chemical composition of galactic stars. We investigate the efficiency of our method using spectroscopically determined stellar metallicities from SDSS DR7. The technique is generic in the sense that it is not restricted to certain stellar types or stellar parameter ranges and makes it possible to obtain metallicities and error estimates for a much larger sample than spectroscopic surveys would allow. We find that our method performs well, especially for brighter stars and higher metallicities and, in contrast to many other techniques, we are able to reliably estimate the error of the predicted metallicities. | [
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.IM"
] | "2013-05-09T19:30:06" |
1408.5595 | Quantum critical behavior of the quantum Ising model on fractal lattices | I study the properties of the quantum critical point of the transverse-field quantum Ising model on various fractal lattices such as the Sierpi\'nski carpet, Sierpi\'nski gasket, and Sierpi\'nski tetrahedron. Using a continuous-time quantum Monte Carlo simulation method and the finite-size scaling analysis, I identify the quantum critical point and investigate its scaling properties. Among others, I calculate the dynamic critical exponent and find that it is greater than one for all three structures. The fact that it deviates from one is a direct consequence of the fractal structures not being integer-dimensional regular lattices. Other critical exponents are also calculated. The exponents are different from those of the classical critical point, and satisfy the quantum scaling relation, thus confirming that I have indeed found the quantum critical point. I find that the Sierpi\'nski tetrahedron, of which the dimension is exactly two, belongs to a different universality class than that of the two-dimensional square lattice. I conclude that the critical exponents depend on more details of the structure than just the dimension and the symmetry. | [
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | "2014-08-24T11:36:39" |
0905.1353 | Fundamental Stellar Astrophysics Revealed at Very High Angular Resolution | A short review of recent results in long-baseline optical interferometry pertaining to fundamental stellar parameters and the future possibilities this area over the next decade. Included are discussions of accurate stellar masses, links between asteroseismology and interferometry, precise radii and effective temperatures, limb darkening and convection, stellar rotation, and high angular resolution imaging. | [
"Physics Archive->astro-ph->astro-ph.SR"
] | "2009-05-08T21:48:37" |
0812.0785 | Characterization of the HD 17156 planetary system | AIMS : To improve the parameters of the HD 17156 system (peculiar due to the eccentric and long orbital period of its transiting planet) and constrain the presence of stellar companions. METHODS : Photometric data were acquired for 4 transits, and high precision radial velocity measurements were simultaneously acquired with SARG@TNG for one transit. The template spectra of HD 17156 was used to derive effective temperature, gravity, and metallicity. A fit of the photometric and spectroscopic data was performed to measure the stellar and planetary radii, and the spin-orbit alignment. Planet orbital elements and ephemeris were derived from the fit. Near infrared adaptive optic images was acquired with ADOPT@TNG. RESULTS: We have found that the star has a radius of R_S = 1.43+/-0.03 R_sun and the planet R_P =1.02+/-0.08 R_jup. The transit ephemeris is T_c = 2454\756.73134+/-0.00020+N*21.21663+/-0.00045 BJD. The analysis of the Rossiter-Mclaughlin effect shows that the system is spin orbit aligned with an angle lambda = 4.8 +/- 5.3 deg. The analysis of high resolution images has not revealed any stellar companion with projected separation between 150 and 1000 AU from HD 17156. | [
"Physics Archive->astro-ph"
] | "2008-12-03T19:36:42" |
2104.05887 | Learning Optimal Parametric Hydrodynamic Database for Vortex-Induced Crossflow Vibration Prediction | The Vortex-induced vibration (VIV) prediction of long flexible cylindrical structures relies on the accuracy of the hydrodynamic database constructed via rigid cylinder forced vibration experiments. However, to create a comprehensive hydrodynamic database with tens of input parameters including vibration amplitudes and frequencies and Reynolds number, surface roughness and so forth is technically challenging and virtually impossible due to the large number of experiments required. The current work presents an alternative approach to approximate the crossflow (CF) hydrodynamic coefficient database in a carefully chosen parameterized form. The learning of the parameters is posed as a constraint optimization, where the objective function is constructed based on the error between the experimental response and theoretical prediction assuming energy balance between fluid and structure. Such a method yields the optimal estimation of the CF parametric hydrodynamic database and produces the VIV response prediction based on the updated hydrodynamic database. The method then was tested on several experiments, including freely-mounted rigid cylinder in large Reynolds number with combined crossflow and inline vibrations and large-scale flexible cylinder test in the Norwegian Deepwater Program, and the result is shown to robustly and significantly reduce the error in predicting cylinder VIVs. | [
"Physics Archive->physics->physics.flu-dyn"
] | "2021-04-13T01:36:03" |
cond-mat/9705124 | Non-interacting Cooper pairs inside a pseudogap | I present a simple analytical model describing the normal state of a superconductor with a pseudogap in the density of states, such as in underdoped cuprates. In nearly two-dimensional systems, where the superconducting transition temperature is reduced from the mean-field BCS value, Cooper pairs may be present as slow fluctuations of the BCS pairing field. Using the self-consistent T-matrix (fluctuation exchange) approach I find that the fermion spectral weight exhibits two BCS-like peaks, broadened by fluctuations of the pairing field amplitude. The density of states becomes suppressed near the Fermi energy, which allows for long-lived low-energy Cooper pairs that propagate as a sound-like mode with a mass. A self-consistency requirement, linking the width of the pseudogap to the intensity of the pairing field, determines the pair condensation temperature. In nearly two-dimensional systems, it is proportional to the degeneracy temperature of the fermions, with a small prefactor that vanishes in two dimensions. | [
"Physics Archive->cond-mat->cond-mat.supr-con"
] | "1997-05-13T21:08:40" |
1603.03672 | Randomized gap and amplitude estimation | We provide a method for estimating spectral gaps in low-dimensional systems. Unlike traditional phase estimation, our approach does not require ancillary qubits nor does it require well characterised gates. Instead, it only requires the ability to perform approximate Haar-random unitary operations, applying the unitary whose eigenspectrum is sought out and performing measurements in the computational basis. We discuss application of these ideas to in-place amplitude estimation and quantum device calibration. | [
"Physics Archive->quant-ph"
] | "2016-03-11T16:01:41" |
2306.17499 | The Implicit Bias of Minima Stability in Multivariate Shallow ReLU Networks | We study the type of solutions to which stochastic gradient descent converges when used to train a single hidden-layer multivariate ReLU network with the quadratic loss. Our results are based on a dynamical stability analysis. In the univariate case, it was shown that linearly stable minima correspond to network functions (predictors), whose second derivative has a bounded weighted $L^1$ norm. Notably, the bound gets smaller as the step size increases, implying that training with a large step size leads to `smoother' predictors. Here we generalize this result to the multivariate case, showing that a similar result applies to the Laplacian of the predictor. We demonstrate the tightness of our bound on the MNIST dataset, and show that it accurately captures the behavior of the solutions as a function of the step size. Additionally, we prove a depth separation result on the approximation power of ReLU networks corresponding to stable minima of the loss. Specifically, although shallow ReLU networks are universal approximators, we prove that stable shallow networks are not. Namely, there is a function that cannot be well-approximated by stable single hidden-layer ReLU networks trained with a non-vanishing step size. This is while the same function can be realized as a stable two hidden-layer ReLU network. Finally, we prove that if a function is sufficiently smooth (in a Sobolev sense) then it can be approximated arbitrarily well using shallow ReLU networks that correspond to stable solutions of gradient descent. | [
"Computer Science Archive->cs.LG"
] | "2023-06-30T09:17:39" |
1006.0811 | Dynamics of phantom model with O(N) symmetry in loop quantum cosmology | Many astrophysical data show that the expansion of our universe is accelerating. In this paper, we study the model of phantom with O(N) symmetry in background of loop quantum cosmology(LQC). We investigate the phase-space stability of the corresponding autonomous system and find no stable node but only 2 saddle points in the field of real numbers. The dynamics is similar to the single-field phantom model in LQC[1]. The effect of O(N) symmetry just influence the detail of the universe's evolution. This is a sharp contrast with the result in general relativity, in which the dynamics of scalar fields models with O$(N)$ symmetry are quite different from the single-field models[2][3][4]. | [
"Physics Archive->gr-qc"
] | "2010-06-04T08:44:36" |
2208.00163 | Resolution enhancement of placenta histological images using deep learning | In this study, a method has been developed to improve the resolution of histological human placenta images. For this purpose, a paired series of high- and low-resolution images have been collected to train a deep neural network model that can predict image residuals required to improve the resolution of the input images. A modified version of the U-net neural network model has been tailored to find the relationship between the low resolution and residual images. After training for 900 epochs on an augmented dataset of 1000 images, the relative mean squared error of 0.003 is achieved for the prediction of 320 test images. The proposed method has not only improved the contrast of the low-resolution images at the edges of cells but added critical details and textures that mimic high-resolution images of placenta villous space. | [
"Computer Science Archive->cs.CV",
"Computer Science Archive->cs.LG",
"Electrical Engineering and Systems Science Archive->eess.IV"
] | "2022-07-30T08:17:37" |
1311.3224 | Non-Gaussian signatures of general inflationary trajectories | We carry out a numerical calculation of the bispectrum in generalised trajectories of canonical, single--field inflation. The trajectories are generated in the Hamilton-Jacobi (HJ) formalism based on Hubble Slow Roll (HSR) parameters. The calculation allows generally shape and scale dependent bispectra, or dimensionless $f_{NL}$, in the out-of-slow-roll regime. The distributions of $f_{NL}$ for various shapes and HSR proposals are shown as an example of how this procedure can be used within the context of Monte Carlo exploration of inflationary trajectories. We also show how allowing out-of-slow-roll behaviour can lead to a bispectrum that is relatively large for equilateral shapes. | [
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | "2013-11-13T17:31:13" |
2012.02688 | ESCAPED: Efficient Secure and Private Dot Product Framework for Kernel-based Machine Learning Algorithms with Applications in Healthcare | To train sophisticated machine learning models one usually needs many training samples. Especially in healthcare settings these samples can be very expensive, meaning that one institution alone usually does not have enough on its own. Merging privacy-sensitive data from different sources is usually restricted by data security and data protection measures. This can lead to approaches that reduce data quality by putting noise onto the variables (e.g., in $\epsilon$-differential privacy) or omitting certain values (e.g., for $k$-anonymity). Other measures based on cryptographic methods can lead to very time-consuming computations, which is especially problematic for larger multi-omics data. We address this problem by introducing ESCAPED, which stands for Efficient SeCure And PrivatE Dot product framework, enabling the computation of the dot product of vectors from multiple sources on a third-party, which later trains kernel-based machine learning algorithms, while neither sacrificing privacy nor adding noise. We evaluated our framework on drug resistance prediction for HIV-infected people and multi-omics dimensionality reduction and clustering problems in precision medicine. In terms of execution time, our framework significantly outperforms the best-fitting existing approaches without sacrificing the performance of the algorithm. Even though we only show the benefit for kernel-based algorithms, our framework can open up new research opportunities for further machine learning models that require the dot product of vectors from multiple sources. | [
"Computer Science Archive->cs.CR",
"Computer Science Archive->cs.LG"
] | "2020-12-04T15:57:20" |
1211.0257 | Multigap Superconductivity in GdFeAsO$_{0.88}$ Evidenced by SnS-Andreev Spectroscopy | Using intrinsic multiple Andreev reflection effect (IMARE) spectroscopy we studied superconducting properties of nearly optimal oxygen-deficient GdFeAsO$_{0.88}$ polycrystalline samples (bulk critical temperatures $T_C^{bulk} = 49 \div 52$\,K). Temperature dependences for two superconducting gaps $\Delta_{L,S}(T)$ ($T_C^{local} = 48 \div 50$\,K) have been measured in the range from 4.2 to 50\,K. The $\Delta_{L,S}(T)$ dependences were found to deviate from the BCS-like function; this suggests an importance of the $k$-space (internal) proximity effect between the two condensates. | [
"Physics Archive->cond-mat->cond-mat.supr-con"
] | "2012-11-01T19:15:44" |
1804.06160 | Quantization of Hamiltonian coactions via twist | In this paper we introduce a notion of quantum Hamiltonian (co)action of Hopf algebras endowed with Drinfel'd twist structure (resp., 2-cocycles). First, we define a classical Hamiltonian action in the setting of Poisson Lie groups compatible with the 2-cocycle stucture and we discuss a concrete example. This allows us to construct, out of the classical momentum map, a quantum momentum map in the setting of Hopf coactions and to quantize it by using Drinfel'd approach. | [
"Mathematics Archive->math.QA"
] | "2018-04-17T10:53:54" |
1806.06800 | Macroscopic ground-state degeneracy and magnetocaloric effect in the exactly solvable spin-1/2 Ising-Heisenberg double-tetrahedral chain | The ground-state degeneracy and magnetocaloric effect in the spin-$1/2$ Ising-Heisenberg double-tetrahedral chain are exactly investigated. It is demonstrated that the zero-temperature phase diagram involves two classical and two quantum chiral phases with distinct degrees of the macroscopic degeneracy. Different macroscopic degeneracies observed in the latter phases and at individual ground-state phase transitions are confirmed by multiple-peak dependencies of the specific heat and entropy on the magnetic field. The cooling capability of the model is well illustrated by the magnetic-field variations of the isothermal entropy change, temperature isotherms and the magnetic Gr\"uneisen parameter. | [
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | "2018-06-18T16:10:46" |
2202.07287 | Local well-posedness for a class of singular Vlasov equations | In this article we study a singular Vlasov system on the torus where the force field has the smoothness of a (fractional) derivative $D^{\alpha}$ of the density, where $\alpha>0$. We prove local well-posedness in Sobolev spaces without restriction on the data. This is in sharp contrast with the case $\alpha=0$ which is ill-posed in Sobolev spaces for general data. | [
"Mathematics Archive->math.AP"
] | "2022-02-15T10:09:03" |
1202.2643 | On the $q$-Genocchi numbers and polynomials with weight zero and their applications | In this paper, the authors deal with the $q$-Genocchi numbers and polynomials with weight zero. They discover some interesting relations via the $p$-adic $q$-integral on $\mathbb{Z}_{p}$ and familiar basis Bernstein polynomials. Finally, the authors show that the $p$-adic $\log$ gamma functions are associated with the $q$-Genocchi numbers and polynomials with weight zero. | [
"Mathematics Archive->math.CO",
"Mathematics Archive->math.NT"
] | "2012-02-13T07:06:14" |
1504.02036 | Magnetocaloric effect in the symmetric spin-1/2 diamond chain with different Land\'e g-factors of Ising and Heisenberg spins | The symmetric spin-1/2 Ising-Heisenberg diamond chain with different Land\'e g-factors of Ising and Heisenberg spins is exactly solved by combining the generalized decoration-iteration transformation and transfer-matrix method. The ground state of the system and magnetocaloric effect during the adiabatic (de)magnetization are particularly examined. It is evidenced that the considered mixed-spin diamond chain exhibits an enhanced magnetocaloric effect during the adiabatic (de)magnetization in the vicinity of field-induced phase transitions as well as in the zero-field limit if the frustrated phase constitutes the zero-field ground state, but the cooling efficiency depends on whether the system is macroscopically degenerate in these parameter regions or not. | [
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | "2015-04-08T17:07:16" |
1810.07597 | Pohozaev identities for a pseudo-relativistic Schr\"odinger operator and applications | In this paper we prove a Pohozaev-type identity for both the problem $(-\Delta+m^2)^su=f(u)$ in $\mathbb{R}^N$ and its harmonic extension to $\mathbb{R}^{N+1}_+$ when $0<s<1$. So, our setting includes the pseudo-relativistic operator $\sqrt{-\Delta+m^2}$ and the results showed here are original, to the best of our knowledge. The identity is first obtained in the extension setting and then "translated" into the original problem. In order to do that, we develop a specific Fourier transform theory for the fractionary operator $(-\Delta+m^2)^s$, which lead us to define a weak solution $u$ of the original problem if the identity \begin{equation}\label{defsola}\int_{\mathbb{R}^N}(-\Delta+m^2)^{s/2}u(-\Delta+m^2)^{s/2}v\dd x=\int_{ \mathbb{R}^N}f(u)v\dd x\tag{S}\end{equation} is satisfied by all $v\in H^{s}(\mathbb{R}^N)$. The obtained Pohozaev-type identity is then applied to prove both a result of nonexistence of solution to the case $f(u)=|u|^{p-2}u$ if $p\geq 2^{*}_s$ and a result of existence of a ground state, if $f$ is modeled by $\kappa u^3/(1+u^2)$, for a constant $\kappa$. In this last case, we apply the Nehari-Pohozaev manifold introduced by D. Ruiz. Finally, we prove that positive solutions of $(-\Delta+m^2)^su=f(u)$ are radially symmetric and decreasing with respect to the origin, if $f$ is modeled by functions like $t^\alpha$, $\alpha\in(1,2^{*}_s-1)$ or $t\ln t$. | [
"Mathematics Archive->math.AP"
] | "2018-10-17T15:00:47" |
1510.03266 | Background suppression in massive TeO$_2$ bolometers with Neganov-Luke amplified light detectors | Bolometric detectors are excellent devices for the investigation of neutrinoless double-beta decay (0$\nu\beta\beta$). The observation of such decay would demonstrate the violation of lepton number, and at the same time it would necessarily imply that neutrinos have a Majorana character. The sensitivity of cryogenic detectors based on TeO$_2$ is strongly limited by the alpha background in the region of interest for the 0$\nu\beta\beta$ of $^{130}$Te. It has been demonstrated that particle discrimination in TeO$_2$ bolometers is possible measuring the Cherenkov light produced by particle interactions. However an event-by-event discrimination with NTD-based light detectors has to be demonstrated. We will discuss the performance of a highly-sensitive light detector exploiting the Neganov-Luke effect for signal amplification. The detector, being operated with NTD-thermistor and coupled to a 750 g TeO$_2$ crystal, shows the ability for an event-by-event identification of electron/gamma and alpha particles. The extremely low detector baseline noise, RMS 19 eV, demonstrates the possibility to enhance the sensitivity of TeO$_2$-based 0$\nu\beta\beta$ experiment to an unprecedented level. | [
"Physics Archive->physics->physics.ins-det"
] | "2015-10-12T13:00:30" |
hep-th/0509072 | Gravity Mediation in 6d Brane-World Supergravity | We consider the gravity-mediated SUSY breaking within the effective theory of six-dimensional brane-world supergravity. We construct the supersymmetric bulk-brane action by Noether method and find the nontrivial moduli coupling of the brane F- and D-terms. We find that the low energy Kahler potential is not of sequestered form, so gravity mediation may occur at tree level. In moduli stabilization with anomaly effects included, the scalar soft mass squared can be positive at tree level and it can be comparable to the anomaly mediation. | [
"Physics Archive->hep->hep-th"
] | "2005-09-09T23:22:52" |
0807.2687 | Bayesian Limits on Primordial Isotropy Breaking | It is often assumed that primordial perturbations are statistically isotropic, which implies, among other properties, that their power spectrum is invariant under rotations. In this article, we test this assumption by placing model-independent bounds on deviations from rotational invariance of the primordial spectrum. Using five-year WMAP cosmic microwave anisotropy maps, we set limits on the overall norm and the amplitude of individual components of the primordial spectrum quadrupole. We find that there is no significant evidence for primordial isotropy breaking, and that an eventually non-vanishing quadrupole has to be subdominant. | [
"Physics Archive->astro-ph"
] | "2008-07-17T18:15:09" |
1407.5778 | Classical distinguishability as an operational measure of polarization | We put forward an operational degree of polarization that can be extended in a natural way to fields whose wave fronts are not necessarily planar. This measure appears as a distance from a state to the set of all its polarization-transformed counterparts. By using the Hilbert-Schmidt metric, the resulting degree is a sum of two terms: one is the purity of the state and the other can be interpreted as a classical distinguishability, which can be experimentally determined in an interferometric setup. For transverse fields, this reduces to the standard approach, whereas it allows one to get a straight expression for nonparaxial fields. | [
"Physics Archive->quant-ph"
] | "2014-07-22T08:11:43" |
1411.3058 | Riemann-Roch isomorphism, Chern-Simons invariant and Liouville action | Using the arithmetic Schottky uniformization theory, we show the arithmeticity of $PSL_{2}({\mathbb C})$ Chern-Simons invariant. In terms of this invariant, we give an explicit formula of the Riemann-Roch isomorphism as Zograf-Mcintyre-Takhtajan's infinite product for families of algebraic curves. By this formula, we determine the unknown constant which appears in the holomorphic factorization formula of determinant of Laplacians on Riemann surfaces via the classical Liouville action. As an application, we show the rationality of Ruelle zeta values for Schottky uniformized $3$-manifolds. | [
"Mathematics Archive->math.AG"
] | "2014-11-12T03:25:26" |
2301.08276 | Cross-validatory model selection for Bayesian autoregressions with exogenous regressors | Bayesian cross-validation (CV) is a popular method for predictive model assessment that is simple to implement and broadly applicable. A wide range of CV schemes is available for time series applications, including generic leave-one-out (LOO) and K-fold methods, as well as specialized approaches intended to deal with serial dependence such as leave-future-out (LFO), h-block, and hv-block. Existing large-sample results show that both specialized and generic methods are applicable to models of serially-dependent data. However, large sample consistency results overlook the impact of sampling variability on accuracy in finite samples. Moreover, the accuracy of a CV scheme depends on many aspects of the procedure. We show that poor design choices can lead to elevated rates of adverse selection. In this paper, we consider the problem of identifying the regression component of an important class of models of data with serial dependence, autoregressions of order p with q exogenous regressors (ARX(p,q)), under the logarithmic scoring rule. We show that when serial dependence is present, scores computed using the joint (multivariate) density have lower variance and better model selection accuracy than the popular pointwise estimator. In addition, we present a detailed case study of the special case of ARX models with fixed autoregressive structure and variance. For this class, we derive the finite-sample distribution of the CV estimators and the model selection statistic. We conclude with recommendations for practitioners. | [
"Statistics Archive->stat.ME"
] | "2023-01-19T19:26:51" |
1104.3048 | Decay of Correlations in a Topological Glass | In this paper we continue the study of a topological glassy system. The state space of the model is given by all triangulations of a sphere with $N$ nodes, half of which are red and half are blue. Red nodes want to have 5 neighbors while blue ones want 7. Energies of nodes with other numbers of neighbors are supposed to be positive. The dynamics is that of flipping the diagonal between two adjacent triangles, with a temperature dependent probability. We consider the system at very low temperatures. We concentrate on several new aspects of this model: Starting from a detailed description of the stationary state, we conclude that pairs of defects (nodes with the "wrong" degree) move with very high mobility along 1-dimensional paths. As they wander around, they encounter single defects, which they then move "sideways" with a geometrically defined probability. This induces a diffusive motion of the single defects. If they meet, they annihilate, lowering the energy of the system. We both estimate the decay of energy to equilibrium, as well as the correlations. In particular, we find a decay like $t^{-0.4}$. | [
"Mathematics Archive->math.MP",
"Physics Archive->cond-mat->cond-mat.stat-mech",
"Physics Archive->math-ph"
] | "2011-04-15T13:22:48" |
1711.01895 | Space dust collisions as a planetary escape mechanism | It is observed that hypervelocity space dust, which is continuously bombarding the Earth, creates immense momentum flows in the atmosphere. Some of this fast space dust inevitably will interact with the atmospheric system, transferring energy and moving particles around, with various possible consequences. This paper examines, with supporting estimates, the possibility that through collisions, the Earth-grazing component of space dust can facilitate planetary escape of atmospheric particles, whether they be the atoms and molecules forming the atmosphere or bigger sized particles. As one interesting outcome, floating in the Earth's atmosphere are a variety of particles containing the telltale signs of Earth's organic story, including microbial life and life essential molecules. This paper will assess the ability for this space dust collision mechanism to propel some of these biological constituents into space. | [
"Physics Archive->astro-ph->astro-ph.EP"
] | "2017-11-06T13:58:20" |
nucl-th/0209067 | Selected Topics in Near Threshold Pion Photoproduction and Compton Scattering off Nucleons | Some open topics in the field of low energy photon-nucleon interactions are discussed--which in my opinion are of interest both for obtaining new information on nucleon structure as well as for precision tests of our theoretical understanding of chiral dynamics. In particular, I discuss p-wave multipoles in charged pion photoproduction off protons as well as the role of spin-dependent effects in (unpolarized) Compton scattering off nucleons. There the concept of dynamical spin polarizabilities is found to be essential for the understanding of differential Compton cross sections above 120 MeV cms photon energy. | [
"Physics Archive->nucl->nucl-th"
] | "2002-09-21T17:42:22" |
2101.10494 | Products in a Category with Only One Object | We consider certain decision problems for the free model of the theory of Cartesian monoids. We introduce a model of computation based on the notion of a single stack one-way PDA due to Ginsburg, Greibach and Harrison. This model allows us to solve problems such as (1) Given a finite set B of elements and an element F, is F a product of members of B? (2) Is the submonoid generated by the finite set B infinite? for certain fragments of the free Cartesian monoid. These fragments include the submonoid of right invertible elements and so our results apply to the Thompson-Higman groups. | [
"Computer Science Archive->cs.LO"
] | "2021-01-26T00:10:18" |
0805.1979 | Loop Group Decompositions in Almost Split Real Forms and Applications to Soliton Theory and Geometry | We prove a global Birkhoff decomposition for almost split real forms of loop groups, when an underlying finite dimensional Lie group is compact. Among applications, this shows that the dressing action - by the whole subgroup of loops which extend holomorphically to the exterior disc - on the $U$-hierarchy of the ZS-AKNS systems, on curved flats and on various other integrable systems, is global for compact cases. It also implies a global infinite dimensional Weierstrass-type representation for Lorentzian harmonic maps (1+1 wave maps) from surfaces into compact symmetric spaces. An "Iwasawa-type" decomposition of the same type of real form, with respect to a fixed point subgroup of an involution of the second kind, is also proved, and an application given. | [
"Mathematics Archive->math.DG",
"Mathematics Archive->math.MP",
"Physics Archive->math-ph"
] | "2008-05-14T07:26:23" |
0802.3968 | Measurement of masses of the $\Xi_c(2645)$ and $\Xi_c(2815)$ baryons and observation of $\Xi_c(2980)\to\Xi_c(2645)\pi$ %and observation of the $\Xi_c(2980)$ and observation of $\Xi_c(2980)\to \Xi_c(2645)\pi$ | We report a precise measurement of the masses of the $\Xi_c(2645)$ and $\Xi_c(2815)$ baryons using a data sample of 414 fb$^{-1}$ collected by the Belle collaboration at the KEKB $e^+ e^-$ collider. The states $\Xi_c(2645)^{0,+}$ are observed in the $\Xi_c^{+,0}\pi^{-,+}$ decay modes, while the $\Xi_c(2815)^{0,+}$ are reconstructed in the $\Xi_c(2645)^{+,0}\pi^{-,+}$ decay modes. The following mass splittings are determined: $m_{\Xi_c(2645)^+} - m_{\Xi_c(2645)^0} = (-0.1 \pm 0.3 ({\rm stat}) \pm 0.6 {(\rm syst})) {\rm MeV}/{\rm c}^2$ and $m_{\Xi_c(2815)^+} - m_{\Xi_c(2815)^0} = (-3.4 \pm 1.9 ({\rm stat}) \pm 0.9 {(\rm syst})) {\rm MeV}/{\rm c}^2$ with a much better precision than the current world averages. We also observe a new decay mode, $\Xi_c(2980)^{0,+} \to \Xi_c(2645)^{+,0}\pi^{-,+}$. | [
"Physics Archive->hep->hep-ex"
] | "2008-02-27T08:09:51" |
1112.4421 | On the non-evolution of the dependence of black hole masses on bolometric luminosities for QSOs | There are extremely luminous quasi stellar objects (QSOs) at high redshift which are absent at low redshift. The lower luminosities at low redshifts can be understood as the external manifestation of either a lower Eddington ratio or a lower mass. To distinguish between both effects, we determine the possible dependence of masses and Eddington ratios of QSOs with a fixed luminosity as a function of redshifts; this avoids the Malmquist bias or any other selection effect. For the masses and Eddington ratios derived for a sample of QSOs in the Sloan Digital Sky Survey, we model their evolution by a double linear fit separating the dependence on redshifts and luminosities. The validity of the fits and possible systematic effects were tested by the use of different estimators of masses or bolometric luminosities, and possible intergalactic extinction effects. The results do not show any significant evolution of black hole masses or Eddington ratios for equal luminosity QSOs. The black hole mass only depends on the bolometric luminosity without significant dependence on the redshift as M_{BH}(10^9 M_sun) = 3.4[L_{bol}(10^{47} erg/s})]^{0.65} on average for z<5. This must not be confused with the possible evolution in the formation of black holes in QSOs. The variations of environment might influence the formation of the black holes but not its subsequent accretion. It also leaves a question to be solved: Why are there not QSOs with very high mass at low redshift? A brief discussion of the possible reasons for this is tentatively pointed out. | [
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.GA"
] | "2011-12-19T17:49:39" |
1905.05153 | On tangency in equisingular families of curves and surfaces | We study the behavior of limits of tangents in topologically equivalent spaces. In the context of families of generically reduced curves, we introduce the $s$-invariant of a curve and we show that in a Whitney equisingular family with the property that the $s$-invariant is constant along the parameter space, the number of tangents of each curve of the family is constant. In the context of families of isolated surface singularities, we show through examples that Whitney equisingularity is not sufficient to ensure that the tangent cones of the family are homeomorphic. We explain how the existence of exceptional tangents is preserved by Whitney equisingularity but their number can change. | [
"Mathematics Archive->math.AG",
"Mathematics Archive->math.CV"
] | "2019-05-13T17:16:37" |
hep-th/0308103 | Regularization of Newton Constant, Trans-Planckian Dispersion Relation, and Symmetry of Particle Spectrum | We consider the possibility that the UV completeness of a fundamental theory is achieved by a modification of propagators at large momenta. We assume that general covariance is preserved at all energies, and focus on the coupling of a scalar field to the background geometry as an example. Naively, one expects that the gravitational interaction, like Yukawa interactions, will be regularized by a propagator which decays to zero sufficiently fast above some cutoff scale, but we show that in order to avoid the ultra-violet divergence, the propagator should approach to a nonzero constant. This incompatibility between the regularizations of gravitational and Yukawa interactions suggests that a symmetry of the particle spectrum is needed for a UV complete fundamental theory. | [
"Physics Archive->hep->hep-th"
] | "2003-08-15T19:13:57" |
1510.05511 | Free fall temperature of Schwarzschild-Tangherlini-AdS black hole | Investigating five-dimensional Schwarzschild-Tangherlini-AdS black hole, we construct a (6+2)-dimensional flat embedding structure. Exploiting this flat manifold, we evaluate a free fall temperature of the black hole in manifold ranging from outer event horizon to the infinity. | [
"Physics Archive->physics->physics.gen-ph"
] | "2015-10-11T00:57:02" |
1611.07055 | A Data Structure for Nearest Common Ancestors with Linking | Consider a forest that evolves via $link$ operations that make the root of one tree the child of a node in another tree. Intermixed with $link$ operations are $nca$ operations, which return the nearest common ancestor of two given nodes when such exists. This paper shows that a sequence of $m$ such $nca$ and $link$ operations on a forest of $n$ nodes can be processed on-line in time $O(m\alpha(m,n)+n)$. This was previously known only for a restricted type of $link$ operation. The special case where a $link$ only extends a tree by adding a new leaf occurs in Edmonds' algorithm for finding a maximum weight matching on a general graph. Incorporating our algorithm into the implementation of Edmonds' algorithm in \cite{G17} achieves time $O(n(m + n\log n))$ for weighted matching, an arguably optimum asymptotic bound ($n$ and $m$ are the number of vertices and edges, respectively). | [
"Computer Science Archive->cs.DS"
] | "2016-11-21T21:10:43" |
2001.00197 | What determines the formation and characteristics of protoplanetary discs? | Planets form in protoplanetary discs. Their masses, distribution, and orbits sensitively depend on the structure of the protoplanetary discs. However, what sets the initial structure of the discs in terms of mass, radius and accretion rate is still unknown. We perform non-ideal MHD numerical simulations using the adaptive mesh refinement code Ramses, of a collapsing, one solar mass, molecular core to study the disc formation and early, up to 100 kyr, evolution, paying great attention to the impact of numerical resolution and accretion scheme. We found that while the mass of the central object is almost independent of the numerical parameters such as the resolution and the accretion scheme onto the sink particle, the disc mass, and to a lower extent its size, heavily depend on the accretion scheme, which we found, is itself resolution dependent. This implies that the accretion onto the star and through the disc are largely decoupled. For a relatively large domain of initial conditions (except at low magnetisation), we found that the properties of the disc do not change too significantly. In particular both the level of initial rotation and turbulence do not influence the disc properties provide the core is sufficiently magnetized. After a short relaxation phase, the disc settles in a stationary state. It then slowly grows in size but not in mass. The disc itself is weakly magnetized but its immediate surrounding is on the contrary highly magnetized. Our results show that the disc properties directly depend on the inner boundary condition, i.e. the accretion scheme onto the central object, suggesting that the disc mass is eventually controlled by the small scale accretion process, possibly the star-disc interaction. Because of ambipolar diffusion and its significant resistivity, the disc diversity remains limited and except for low magnetisation, their properties are (abridged). | [
"Physics Archive->astro-ph->astro-ph.GA"
] | "2020-01-01T12:32:47" |
1009.1034 | On the stability of the thermal Comptonization index in neutron star low-mass X-ray binaries in their different spectral states | Most of the spectra of neutron star low mass X-ray binaries (NS LMXBs), being them persistent or transient, are characterized by the presence of a strong thermal Comptonization bump, thought to originate in the transition layer (TL) between the accretion disk and the NS surface. The observable quantities which characterize this component dominating the emission below 30 keV, are the spectral index alpha and the rollover energy, both related to the electron temperature and optical depth of the plasma. Starting from observational results on a sample of NS LMXBs in different spectral states, we formulate the problem of X-ray spectral formation in the TL of these sources. We predict a stability of the thermal Comptonization spectral index in different spectral states if the energy release in the TL is much higher than the intercepted flux coming from the accretion disk. We use an equation for the energy balance and the radiative transfer diffusion equation for a slab geometry in the TL, to derive a formula for the thermal Comptonization index alpha. We show that in this approximation the TL electron temperature kTe and optical depth tau_0 can be written as a function of the energy flux from the disk intercepted by the corona (TL) and that in the corona itself Qdisk/Qcor, in turn leading to a relation alpha=f(Qdisk/Qcor), with alpha ~ 1 when Qdisk/Qcor <<1. We show that the observed spectral index alpha for the sample of sources here considered lies in a belt around 1 +/- 0.2 a part for the case of GX 354--0. Comparing our theoretical predictions with observations, we claim that this result, which is consistent with the condition Qdisk/Qcor <<1, can give us constraints on the accretion geometry of these systems, an issue that seems difficult to be solved using only the spectral analysis method. | [
"Physics Archive->astro-ph->astro-ph.HE"
] | "2010-09-06T11:59:59" |
2303.07796 | Limit laws of maximal Birkhoff sums for circle rotations via quantum modular forms | In this paper, we show how quantum modular forms naturally arise in the ergodic theory of circle rotations. Working with the classical Birkhoff sum $S_N(\alpha)=\sum_{n=1}^N (\{ n \alpha \}-1/2)$, we prove that the maximum and the minimum as well as certain exponential moments of $S_N(r)$ as functions of $r \in \mathbb{Q}$ satisfy a direct analogue of Zagier's continuity conjecture, originally stated for a quantum invariant of the figure-eight knot. As a corollary, we find the limit distribution of $\max_{0 \le N<M} S_N(\alpha)$ and $\min_{0 \le N<M} S_N(\alpha)$ with a random $\alpha \in [0,1]$. | [
"Mathematics Archive->math.DS",
"Mathematics Archive->math.NT"
] | "2023-03-14T11:11:18" |
gr-qc/9504048 | A Judgement on Sinors | This note contains some comments on a recent paper by Friedman on two-component spinors in spacetimes which do not admit a time-orientation, and is intended to clarify the relation of the work reported in that paper to previous literature. | [
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | "1995-04-27T18:23:46" |
1901.07616 | Conic Representations of Topological Groups | We define basic notions in the category of conic representations of a topological group and prove elementary facts about them. We show that a conic representation determines an ordinary dynamical system of the group together with a multiplier, establishing facts and formulae connecting the two categories. The topic is also closely related to the affine representations of the group. The central goal was attaining a better understanding of irreducible conic representations of a group, and - particularly - to determine whether there is a phenomenon analogous to the existence of a universal irreducible affine representation of a group in our category (the general answer is negative). Then we inspect embeddings of irreducible conic representations of semi-simple Lie groups in some "regular" conic representation they possess. We conclude with what is known to us about the irreducible conic representations of $SL_{2}\left(\mathbb{R}\right)$. | [
"Mathematics Archive->math.DS"
] | "2019-01-22T21:20:28" |
1710.04832 | Subextensions for co-induced modules | Using cohomological methods, we prove a criterion for the embedding of a group extension with abelian kernel into the split extension of a co-induced module. This generalises some earlier similar results. We also prove an assertion about the conjugacy of complements in split extensions of co-induced modules. Both results follow from a relation between homomorphisms of certain cohomology groups. | [
"Mathematics Archive->math.GR"
] | "2017-10-13T08:22:26" |
2312.08120 | Statistical model concept to quantify input and output of water, nitrogen and phosphorus for lakes with partly gauged watersheds | Valid mass load predictions of nutrients, in particular nitrogen (N) and phosphorus (P), are needed for the limnological understanding of single lake ecosystems as well as larger river/lake ecosystems. The mass of N and P that enters a lake will determine the ecological state of the lake, and the mass release from the lake will determine the ecological state of downstream ecosystems. Hence, establishing sound quantifications of the external load is crucial and e.g. contributes to the foundation of assessments of necessary management interventions to improve or preserve the ecological integrity of lakes. The external load of N and P is an integral of several pathways, each having different contributions to the total mass load. Around the world, balances of N and P have been derived for decades to support both lake water quality monitoring and research, but it can be difficult and, thus, costly to make detailed and sufficiently covering measurement campaigns in all tributaries (surface as well as groundwater) in the watershed of the N and P load including seasonality and temporal change from year to year. Thus, load prediction is facing challenge of uncertainty due to unmeasured loads, which can be a consequence of limited resources available for the water flow recordings and water concentration measurements in inlets around the lake, or simply due to invisible water flow taking place through the lake bottom. The lake outlet will typically take place in one single river, so the outlet recording seems easier to measure than inlets, however, the outlet may also have unmeasured parts in cases where water is leaching out though the lake bottom. In this paper, we propose a method that applies incomplete data sets (incomplete in the sense of temporal frequency and percentage of gauged watershed) to generate time series that predict the N and P loads entering and leaving the lake. | [
"Quantitative Biology Archive->q-bio.QM"
] | "2023-12-13T13:20:29" |
math/0103171 | Singular Monge-Ampere foliations | This replaces the previous version, by correcting an error in the proof of Theorem 1.4, that was pointed out by the referee. | [
"Mathematics Archive->math.CV",
"Mathematics Archive->math.DG"
] | "2001-03-26T19:17:31" |
1209.6496 | On the central helium-burning variable stars of the LeoI dwarf spheroidal galaxy | We present a study of short period, central helium-burning variable stars in the Local Group dwarf spheroidal galaxy LeoI, including 106 RR Lyrae stars and 51 Cepheids. So far, this is the largest sample of Cepheids and the largest Cepheids to RR Lyrae ratio found in such a kind of galaxy. The comparison with other Local Group dwarf spheroidals, Carina and Fornax, shows that the period distribution of RR Lyrae stars is quite similar, suggesting similar properties of the parent populations, whereas the Cepheid period distribution in LeoI peaks at longer periods (P \sim 1.26d instead of ~0.5d) and spans over a broader range, from 0.5 to 1.78d. Evolutionary and pulsation predictions indicate, assuming a mean metallicity peaked within -1.5<= [Fe/H]<=-1.3, that the current sample of LeoI Cepheids traces a unique mix of Anomalous Cepheids (blue extent of the red--clump, partially electron degenerate central helium-burning stars) and short-period classical Cepheids (blue-loop, quiescent central helium-burning stars). Current evolutionary prescriptions also indicate that the transition mass between the two different groups of stars is MHeF \sim 2.1 Mo, and it is constant for stars metal-poorer than [Fe/H]\sim-0.7. Finally, we briefly outline the different implications of the current findings on the star formation history of LeoI. | [
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.GA"
] | "2012-09-28T11:54:12" |
cond-mat/9807192 | Auger transition from orbitally degenerate systems: Effects of screening and multielectron excitations | We calculate Auger spectra given by the two-hole Green's function from orbitally degenerate Hubbard-like models as a function of correlation strength and band filling. The resulting spectra are qualitatively different from those obtained from fully-filled singly degenerate models due to the presence of screening dynamics and multielectron excitations. Application to a real system shows remarkable agreement with experimental results leading to reinterpretation of spectral features. | [
"Physics Archive->cond-mat->cond-mat.str-el"
] | "1998-07-14T03:15:13" |
1511.06483 | Directional Initial Access for Millimeter Wave Cellular Systems | The millimeter wave (mmWave) bands have recently attracted considerable interest for next-generation cellular systems due to the massive available bandwidths at these frequencies. However, a key challenge in designing mmWave cellular systems is initial access -- the procedure by which a mobile establishes an initial link-layer connection to a base station cell. MmWave communication relies on highly directional transmissions and the initial access procedure must thus provide a mechanism by which initial transmission directions can be searched in a potentially large angular space. Design options are compared considering different scanning and signaling procedures to evaluate access delay and system overhead. The channel structure and multiple access issues are also considered. The analysis demonstrates significant benefits of low-resolution fully digital architectures in comparison to single stream analog beamforming. | [
"Computer Science Archive->cs.IT",
"Computer Science Archive->cs.NI",
"Mathematics Archive->math.IT"
] | "2015-11-20T03:30:51" |
2107.03136 | Design of the monodomain model by artificial neural networks | We propose an optimal control approach in order to identify the nonlinearity in the monodomain model, from given data. This data-driven approach gives an answer to the problem of selecting the model when studying phenomena related to cardiac electrophysiology. Instead of determining coefficients of a prescribed model (like the FitzHugh-Nagumo model for instance) from empirical observations, we design the model itself, in the form of an artificial neural network. The relevance of this approach relies on the approximation capacities of neural networks. We formulate this inverse problem as an optimal control problem, and provide mathematical analysis and derivation of optimality conditions. One of the difficulties comes from the lack of smoothness of activation functions which are classically used for training neural networks. Numerical simulations demonstrate the feasibility of the strategy proposed in this work. | [
"Mathematics Archive->math.AP",
"Mathematics Archive->math.OC"
] | "2021-07-07T10:41:19" |
math/0503111 | Combinatorial characterizations of generalized Cohen-Macaulay monomial ideals | We give a generalization of Hochster's formula for local cohomologies of square-free monomial ideals to monomial ideals, which are not necessarily square-free. Using this formula, we give combinatorial characterizations of generalized Cohen-Macaulay monomial ideals. We also give other applications of the generalized Hochster's formula. | [
"Mathematics Archive->math.AC"
] | "2005-03-06T07:33:54" |
1207.6576 | From linear stability analysis to three-dimensional organisation in an incompressible open cavity flow | Three-dimensional direct numerical simulations of an incompressible open square cavity flow are conducted. Features of the permanent (non-linear) regime together with the linear stability analysis of a two-dimensional steady base flow are discussed. Spanwise boundary conditions are periodic and control parameters set such that the shear layer is stable against Kelvin-Helmholtz modes. Three branches of destabilising modes are found. The most destabilising branch is associated with steady modes, over a finite range of spanwise wavenumbers. The two other branches provide unsteady modes. Features of each branches are recovered in the permanent regime: wavelength of the most powerful spanwise Fourier mode, swaying phenomenon, angular frequencies, indicating that modes of each branches are selected and interact in the permanent flow. | [
"Physics Archive->physics->physics.flu-dyn"
] | "2012-07-27T15:45:47" |
2212.06428 | Privacy-preserving Security Inference Towards Cloud-Edge Collaborative Using Differential Privacy | Cloud-edge collaborative inference approach splits deep neural networks (DNNs) into two parts that run collaboratively on resource-constrained edge devices and cloud servers, aiming at minimizing inference latency and protecting data privacy. However, even if the raw input data from edge devices is not directly exposed to the cloud, state-of-the-art attacks targeting collaborative inference are still able to reconstruct the raw private data from the intermediate outputs of the exposed local models, introducing serious privacy risks. In this paper, a secure privacy inference framework for cloud-edge collaboration is proposed, termed CIS, which supports adaptively partitioning the network according to the dynamically changing network bandwidth and fully releases the computational power of edge devices. To mitigate the influence introduced by private perturbation, CIS provides a way to achieve differential privacy protection by adding refined noise to the intermediate layer feature maps offloaded to the cloud. Meanwhile, with a given total privacy budget, the budget is reasonably allocated by the size of the feature graph rank generated by different convolution filters, which makes the inference in the cloud robust to the perturbed data, thus effectively trade-off the conflicting problem between privacy and availability. Finally, we construct a real cloud-edge collaborative inference computing scenario to verify the effectiveness of inference latency and model partitioning on resource-constrained edge devices. Furthermore, the state-of-the-art cloud-edge collaborative reconstruction attack is used to evaluate the practical availability of the end-to-end privacy protection mechanism provided by CIS. | [
"Computer Science Archive->cs.CR"
] | "2022-12-13T08:36:11" |
0804.0908 | Canonical description of D=10 superstring formulated in supertwistor space | Canonical description of the D=10 superstring action involving supertwistor variables generalizing Penrose-Ferber supertwistors is developed. Primary and secondary constraints are identified and arranged into the first- and second-class sets. Dirac brackets are introduced and the deformation of the Poisson bracket algebra of the first-class constraints is studied. The role of the deformation parameter is played by alpha'. | [
"Physics Archive->hep->hep-th"
] | "2008-04-06T13:52:25" |
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💻 GitHub: https://github.com/sebischair/FusionSent
This is a dataset of scientific documents derived from arXiv metadata. The arXiv metadata provides information about more than 2 million scholarly articles published in arXiv from various scientific fields. We use this metadata to create a dataset of 203,961 titles and abstracts categorized into 130 different classes. To this end, we first perform stratified downsampling of the metadata to only 10% of all articles while retaining the original class distribution. Afterward, articles assigned to categories occurring less than 100 times in the downsampled dataset are removed. To obtain the final dataset, we then perform a stratified train/validation/test split of the processed dataset in an 80:10:10 ratio. The number of examples in each set is shown in the table below.
- The
defaultsubset contains the dataset with the document categories as classes in the form of lists of strings. The categories are ordered hierarchically according to the arXiv category taxonomy. In this dataset, the->symbols indicate aparent->childrelationship between categories that can be linked and create a path from the root to the leaf node. For classification, you can either use the complete paths as classes or just parse the respective leaf nodes as classes, resulting in the same (abbreviated) categories. - The
arxiv_category_descriptionssubset contains the tags, names, and textual descriptions of the leaf nodes from the arXiv category taxonomy.
| Split | Number of Samples |
|---|---|
| Train | 163,168 |
| Validation | 20,396 |
| Test | 20,397 |
Each article in the resulting arXiv dataset is categorized into one or more distinct categories. The figure below shows the distribution of papers across the 130 categories of the dataset.
License
MIT
Citation information
When citing our work in academic papers and theses, please use this BibTeX entry:
@inproceedings{schopf-etal-2024-efficient,
title = "Efficient Few-shot Learning for Multi-label Classification of Scientific Documents with Many Classes",
author = "Schopf, Tim and
Blatzheim, Alexander and
Machner, Nektarios and
Matthes, Florian",
editor = "Abbas, Mourad and
Freihat, Abed Alhakim",
booktitle = "Proceedings of the 7th International Conference on Natural Language and Speech Processing (ICNLSP 2024)",
month = oct,
year = "2024",
address = "Trento",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2024.icnlsp-1.21",
pages = "186--198",
}
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