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|---|---|---|---|---|
1606.06262
|
Necessary N-representability Constraints from Time-reversal Symmetry for Periodic Systems
|
The variational calculation of the two-electron reduced density matrix (2-RDM) is extended to periodic molecular systems. If the 2-RDM theory is extended to the periodic case without consideration of time-reversal symmetry, however, it can yields energies that are significantly lower than the correct energies. We derive and implement linear constraints that enforce time-reversal symmetry on the 2-RDM without destroying its computationally favorable block-diagonal structure from translational invariance. Time-reversal symmetry is distinct from space-group or spin (SU(2)) symmetries which can be expressed by unitary transformations. The time-reversal symmetry constraints are demonstrated through calculations of the metallic hydrogen chain and the one-dimensional lithium hydride crystal.
|
[
"Physics Archive->physics->physics.chem-ph"
] | 2016-06-20T19:29:49Z |
hep-th/0210255
|
Poincar\'e algebra and space-time critical dimensions for paraspinning strings
|
In this paper, we paraquantize the spinning string theory in the Neuveu-Shwarz model. Both the center of mass variables and the excitation modes of the string verify paracommutation relations. Except the $[p^{\mu},p^{\nu}]$ commutator, the two other commutators of Poincar\'e algebra are satisfied. With the sole use of trilinear relations we find existence possibilities of spinning strings at space-time dimensions other than D=10.
|
[
"Physics Archive->hep->hep-th"
] | 2002-10-27T13:37:49Z |
hep-th/0401130
|
On the Energy-Momentum Density of Gravitational Plane Waves
|
By embedding Einstein's original formulation of GR into a broader context we show that a dynamic covariant description of gravitational stress-energy emerges naturally from a variational principle. A tensor $T^G$ is constructed from a contraction of the Bel tensor with a symmetric covariant second degree tensor field $\Phi$ and has a form analogous to the stress-energy tensor of the Maxwell field in an arbitrary space-time. For plane-fronted gravitational waves helicity-2 polarised (graviton) states can be identified carrying non-zero energy and momentum.
|
[
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | 2004-01-20T08:03:47Z |
2110.10389
|
Does Data Repair Lead to Fair Models? Curating Contextually Fair Data To Reduce Model Bias
|
Contextual information is a valuable cue for Deep Neural Networks (DNNs) to learn better representations and improve accuracy. However, co-occurrence bias in the training dataset may hamper a DNN model's generalizability to unseen scenarios in the real world. For example, in COCO, many object categories have a much higher co-occurrence with men compared to women, which can bias a DNN's prediction in favor of men. Recent works have focused on task-specific training strategies to handle bias in such scenarios, but fixing the available data is often ignored. In this paper, we propose a novel and more generic solution to address the contextual bias in the datasets by selecting a subset of the samples, which is fair in terms of the co-occurrence with various classes for a protected attribute. We introduce a data repair algorithm using the coefficient of variation, which can curate fair and contextually balanced data for a protected class(es). This helps in training a fair model irrespective of the task, architecture or training methodology. Our proposed solution is simple, effective, and can even be used in an active learning setting where the data labels are not present or being generated incrementally. We demonstrate the effectiveness of our algorithm for the task of object detection and multi-label image classification across different datasets. Through a series of experiments, we validate that curating contextually fair data helps make model predictions fair by balancing the true positive rate for the protected class across groups without compromising on the model's overall performance.
|
[
"Computer Science Archive->cs.CV"
] | 2021-10-20T06:00:03Z |
quant-ph/0208180
|
Experimental demonstration of a controlled-NOT wave-packet gate
|
We report the experimental demonstration of a controlled-NOT (CNOT) quantum logic gate between motional and internal state qubits of a single ion where, as opposed to previously demonstrated gates, the conditional dynamics depends on the extent of the ion's wave-packet. Advantages of this CNOT gate over one demonstrated previously are its immunity from Stark shifts due to off-resonant couplings and the fact that an auxiliary internal level is not required. We characterize the gate logic through measurements of the post-gate ion state populations for both logic basis and superposition input states, and we demonstrate the gate coherence via an interferometric measurement.
|
[
"Physics Archive->quant-ph"
] | 2002-08-28T20:41:17Z |
1205.2455
|
Entangling electrons by splitting Cooper pairs: Two-particle conductance resonance and time coincidence measurements
|
Entanglement, being at the heart of the Einstein-Podolsky-Rosen (EPR) paradox, is a necessary ingredient in processing quantum information. Cooper pairs in superconductors - being composites of two fully entangled electrons - can be split adiabatically, thus forming entangled electrons. We fabricated such electron splitter by contacting an aluminum superconductor strip at the center of a suspended InAs nanowire; terminated at both ends with two normal metallic drains. Intercepting each half of the nanowire by gate - induced Coulomb blockaded quantum dot strongly impeded the flow of Cooper pairs due to large charging energy, while still permitting passage of single electrons. Here, we provide conclusive evidence of extremely high efficiency Cooper pairs splitting via observing positive average (conductance) and time (shot noise) correlations of the split electrons in the two opposite drains of the nanowire. Moreover, The actual charge of the injected quasiparticles was verified by shot noise measurements.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall"
] | 2012-05-11T08:22:29Z |
quant-ph/0406050
|
Temporal Dynamics of Photon Pairs Generated by an Atomic Ensemble
|
The time dependence of nonclassical correlations is investigated for two fields (1,2) generated by an ensemble of cold Cesium atoms via the protocol of Duan et al. [Nature Vol. 414, p. 413 (2001)]. The correlation function R(t1,t2) for the ratio of cross to auto-correlations for the (1,2) fields at times (t1,t2) is found to have a maximum value Rmax=292(+-)57, which significantly violates the Cauchy-Schwarz inequality R<=1 for classical fields. Decoherence of quantum correlations is observed over 175 ns, and is described by our model, as is a new scheme to mitigate this effect.
|
[
"Physics Archive->quant-ph"
] | 2004-06-08T23:10:54Z |
2210.04395
|
Note on the dissipation for the general Muskat problem
|
We consider the dissipation of the Muskat problem and we give an elementary proof of a surprising inequality of Constantin-Cordoba-Gancedo-Strain which holds in greater generality.
|
[
"Mathematics Archive->math.AP"
] | 2022-10-10T01:58:48Z |
2310.11680
|
Trimmed Mean Group Estimation of Average Treatment Effects in Ultra Short T Panels under Correlated Heterogeneity
|
Under correlated heterogeneity, the commonly used two-way fixed effects estimator is biased and can lead to misleading inference. This paper proposes a new trimmed mean group (TMG) estimator which is consistent at the irregular rate of n^{1/3} even if the time dimension of the panel is as small as the number of its regressors. Extensions to panels with time effects are provided, and a Hausman-type test of correlated heterogeneity is proposed. Small sample properties of the TMG estimator (with and without time effects) are investigated by Monte Carlo experiments and shown to be satisfactory and perform better than other trimmed estimators proposed in the literature. The proposed test of correlated heterogeneity is also shown to have the correct size and satisfactory power. The utility of the TMG approach is illustrated with an empirical application.
|
[
"Economics Archive->econ.EM"
] | 2023-10-18T03:04:59Z |
0802.2297
|
Predictive approach to some quantum paradoxes
|
In classical probability theory, the best predictor of a future observation of a random variable $X,$ is its expected value $E_P[X]$ when no other information is available When information consisting in the observation of another random variable $Y$ is available, then the best predictor of $X$ is another random variable $E_P[X|Y].$ It is the purpose of this note to explore the analogue of this in the case of quantum mechanics. We shall see that exactly as in classical prediction theory, when the result of an observation is taken into account by means of a non-commutative conditional expectation, some of the usual paradoxes cease to be such.
|
[
"Mathematics Archive->math.MP",
"Mathematics Archive->math.PR",
"Physics Archive->math-ph"
] | 2008-02-15T23:13:40Z |
1610.01156
|
Massive Close Pairs Measure Rapid Galaxy Assembly in Mergers at High Redshift
|
We compare mass-selected close pairs at z > 1 with the intrinsic galaxy merger rate in the Illustris Simulations. To do so, we construct three 140 arcmin^2 lightcone catalogs and measure pair fractions, finding that they change little or decrease with increasing redshift at z > 1. Consistent with current surveys, this trend requires a decrease in the merger-pair observability time, roughly as (1 + z)^-2, in order to measure the merger rates of the same galaxies. This implies that major mergers are more common at high redshift than implied by the simplest arguments assuming a constant observability time. Several effects contribute to this trend: (1) The fraction of massive, major (4:1) pairs which merge by today increases weakly from ~0.5 at z=1 to ~0.8 at z=3. (2) The median time elapsed between an observed pair and final remnant decreases by a factor of two from z~1 to z~3. (3) An increasing specific star formation rate (sSFR) decreases the time during which common stellar-mass based pair selection criteria could identify the mergers. The average orbit of the pairs at observation time varies only weakly, suggesting that the dynamical time is not varying enough to account by itself for the pair fraction trends. Merging pairs reside in dense regions, having overdensity ~10 to ~100 times greater than the average massive galaxy. We forward model the pairs to reconstruct the merger remnant production rate, showing that it is consistent with a rapid increase in galaxy merger rates at z > 1.
|
[
"Physics Archive->astro-ph->astro-ph.GA"
] | 2016-10-04T20:00:00Z |
1809.02594
|
Feasibility of a resonance-based Planet Nine search
|
It has been proposed that mean motion resonances (MMRs) between Planet Nine and distant objects of the scattered disk might inform the semimajor axis and instantaneous position of Planet Nine. Within the context of this hypothesis, the specific distribution of occupied MMRs largely determines the available constraints. Here we characterize the behavior of scattered Kuiper Belt objects arising in the presence of an eccentric Planet Nine ($e_9 \in 0.1$, $0.7$), focusing on relative sizes of populations occupying particular commensurabilities. Highlighting the challenge of predicting the exact MMR of a given object, we find that the majority of resonant test particles have period ratios with Planet Nine other than those of the form $P_9/P=N/1$, $N/2$ $(N \in \mathbb{Z}^+)$. Taking into account the updated prior distribution of MMRs outlined in this work, we find that the close spacing of high-order resonances, as well as chaotic transport, preclude resonance-based Planet Nine constraints from current observational data.
|
[
"Physics Archive->astro-ph->astro-ph.EP"
] | 2018-09-07T17:37:47Z |
1210.0130
|
Fracture Strength of AlLiB14
|
The orthorhombic boride crystal family XYB$_{14}$, where X and Y are metal atoms, plays a critical role in a unique class of superhard compounds, yet there have been no studies aimed at understanding the origin of the mechanical strength of this compound. We present here the results from a comprehensive investigation into the fracture strength of the archetypal AlLiB$_{14}$ crystal. First-principles, \textit{ab initio}, methods are used to determine the ideal brittle cleavage strength for several high-symmetry orientations. The elastic tensor and the orientation-dependent Young's modulus are calculated. From these results the lower bound fracture strength of AlLiB$_{14}$ is predicted to be between 29 and 31 GPa, which is near the measured hardness reported in the literature. These results indicate that the intrinsic strength of AlLiB$_{14}$ is limited by the interatomic B--B bonds that span between the B layers.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2012-09-29T17:05:26Z |
1402.5303
|
Diffuse Reflection Radius in a Simple Polygon
|
It is shown that every simple polygon in general position with $n$ walls can be illuminated from a single point light source $s$ after at most $\lfloor (n-2)/4\rfloor$ diffuse reflections, and this bound is the best possible. A point $s$ with this property can be computed in $O(n\log n)$ time. It is also shown that the minimum number of diffuse reflections needed to illuminate a given simple polygon from a single point can be approximated up to an additive constant in polynomial time.
|
[
"Computer Science Archive->cs.CG"
] | 2014-02-21T14:33:25Z |
astro-ph/0411674
|
Variability Analysis: Detection and Classification
|
Gaia mission will offer an exceptional opportunity to perform variability studies. The data homogeneity, its optimised photometric systems, composed of 11 medium and 4-5 broad bands, the high photometric precision in G band of one milli-mag for V=13-15, the radial velocity measurements and the exquisite astrometric precision for one billion stars will permit a detailed description of variable objects like stars, quasars and asteroids. However the time sampling and the total number of measurements change from one object to an other because of the satellite scanning law. The data analysis is a challenge because of the huge amount of data, the complexity of the observed objects and the peculiarities of the satellite, and needs a thorough preparation. Experience can be gained by the study of past and present survey analysis and results and Gaia should be put in perspective with the future large scale surveys, like Pan-STARRS or LSST. We present the activities of the Variable Star Working Group and a general plan to digest this unprecedented data set, focusing here on the photometry.
|
[
"Physics Archive->astro-ph"
] | 2004-11-24T21:05:26Z |
1212.0840
|
Intense look at Virgo Southern Extension
|
We collected data on radial velocities and distances of galaxies to elucidate structure and kinematics of the filament attached to the Virgo cluster from south. In the region RA = [12.5 - 13.5]h, Dec = [-20 - 0]deg there are 171 galaxies with radial velocities VLG < 2000 km/s, and 98 of them have distance estimates. This galaxy cloud, called as "Virgo Southern Extension", is situated just on the edge of the Virgo "zero-velocity surface". The mean distance to Virgo SEx, 17pm2 Mpc, and the average radial velocity, 1172pm23 km/s, are very close to the Virgo cluster ones. In Supergalactic coordinates the Virgo SEx dimensions are 15x7x2 Mpc, where the major axis is directed along the line of sight, the second-major axis looks towards the Virgo core and the minor one is perpendicular to the Supergalactic plane. This flattened cloud consists of a dozen virialized groups with the total K-band luminosity of 1.7cdot10^12 Lsol and the total virial mass of 6.3cdot10^13 Msol, having a typical dark matter-to-stellar matter ratio of 37. The Hubble diagram for Virgo SEx galaxies exhibits a tendency of Z-shape wave with a velocity amplitude of ~250 km/s that may be caused by a mass overdensity of ~6cdot10^13 Msol, and in order of magnitude agrees with the sum of virial masses of the groups.
|
[
"Physics Archive->astro-ph->astro-ph.CO"
] | 2012-12-04T19:59:15Z |
0808.3461
|
BV photometry of a possible open star cluster pair NGC 7031/NGC 7086
|
We present a CCD BV photometry of the possible binary open star cluster NGC 7031/NGC 7086. The aim is to confirm or disprove their common nature on the grounds of their age and distance. An age of 224 $\pm$ 25 Myr and distance 831 $\pm$ 72 pc was determined for NGC 7031 and 178 $\pm$ 25 Myr, 955 $\pm$ 84 pc for NGC 7086, respectively. Based on these differences in age and distance we conclude that the two clusters are most likely not formed together from one and the same Giant Molecular Cloud and thus are not a true binary cluster.
|
[
"Physics Archive->astro-ph"
] | 2008-08-26T09:13:00Z |
1504.01422
|
Helioseismic Investigation of Modeled and Observed Supergranule Structure
|
The subsurface structure of an "average" supergranule is derived from existing HMI pipeline time-distance data products and compared to the best helioseismic flow model detailed in Duvall and Hanasoge (2013). We find that significant differences exist between them. Unlike the shallow structure predicted by the model, the average HMI supergranule is very extended in depth, exhibiting horizontal outflow down to $7$--$10$~Mm, followed by a weak inflow reaching a depth of $\sim20$~Mm below the photosphere. The maximal velocities in the horizontal direction for the average supergranule are much smaller than the model, and its near-surface flow field RMS value is about an order of magnitude smaller than the often-quoted values of $\sim250-350$~$\rm{m\,s^{-1}}$ for supergranulation. Much of the overall HMI supergranule structure and its weak flow amplitudes can be explained by examining the HMI pipeline averaging kernels for the near-surface inversions, which are found to be very broad in depth, and nearly identical to one another in terms of sensitivity along the $z$-direction. We also show that forward-modeled travel times in the Born approximation using the model (derived from a ray theory approach) are inconsistent with measured travel times for an average supergranule at any distance. Our findings suggest systematic inaccuracies in the typical techniques used to study supergranulation, confirming some of the results in Duvall and Hanasoge (2013).
|
[
"Physics Archive->astro-ph->astro-ph.SR"
] | 2015-04-06T21:44:47Z |
math/0609439
|
Periods for irregular singular connections on surfaces
|
We define homology groups for flat irregular singular connections on surfaces and a pairing between these and the de Rham cohomology of the connection, generalizing work of S. Bloch and H. Enault in dimension one. Assuming a conjecture of C. Sabbah (known to be true if the rank of the vector bundle is at most 5), we prove perfectness of the pairing. We comment on certain new phenomena appearing in dimension two.
|
[
"Mathematics Archive->math.AG"
] | 2006-09-15T10:06:24Z |
1503.01642
|
Photostrictive materials
|
Light-matter interactions that lead to nonthermal changes in size of the sample constitute a photostrictive effect in many compounds. The photostriction phenomenon was observed in four main groups of materials, ferroelectrics, polar, and non-polar semiconductors, as well as in organic-based materials that are reviewed here. The key mechanisms of photostriction and its dependence on several parameters and perturbations are assessed. The major literature of the photostriction is surveyed, and the review ends with a summary of the proposed technical applications.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2015-03-05T14:26:48Z |
1607.04679
|
Schnorr randomness for noncomputable measures
|
This paper explores a novel definition of Schnorr randomness for noncomputable measures. We say $x$ is uniformly Schnorr $\mu$-random if $t(\mu,x)<\infty$ for all lower semicomputable functions $t(\mu,x)$ such that $\mu\mapsto\int t(\mu,x)\,d\mu(x)$ is computable. We prove a number of theorems demonstrating that this is the correct definition which enjoys many of the same properties as Martin-L\"of randomness for noncomputable measures. Nonetheless, a number of our proofs significantly differ from the Martin-L\"of case, requiring new ideas from computable analysis.
|
[
"Mathematics Archive->math.LO"
] | 2016-07-15T23:00:23Z |
1211.6528
|
An Independent Measurement of the Incidence of MgII Absorbers along Gamma-Ray Burst Sightlines: the End of the Mystery?
|
In 2006, Prochter et al. reported a statistically significant enhancement of very strong Mg II absorption systems intervening the sightlines to gamma-ray bursts (GRBs) relative to the in- cidence of such absorption along quasar sightlines. This counterintuitive result, has inspired a diverse set of astrophysical explanations (e.g. dust, gravitational lensing) but none of these has obviously resolved the puzzle. Using the largest set of GRB afterglow spectra available, we reexamine the purported enhancement. In an independent sample of GRB spectra with a survey path 3 times larger than Prochter et al., we measure the incidence per unit redshift of $\geq 1$\AA rest-frame equivalent width Mg II absorbers at $z \approx 1$ to be l(z)= 0.18 $\pm$ 0.06. This is fully consistent with current estimates for the incidence of such absorbers along quasar sightlines. Therefore, we do not confirm the original enhancement and suggest those results suffered from a statistical fluke. Signatures of the original result do remain in our full sample (l(z) shows an $\approx 1.5$ enhancement over l(z)QSO), but the statistical significance now lies at $\approx 90%$ c.l. Restricting our analysis to the subset of high-resolution spectra of GRB afterglows (which overlaps substantially with Prochter et al.), we still reproduce a statistically significant enhancement of Mg II absorption. The reason for this excess, if real, is still unclear since there is no connection between the rapid afterglow follow-up process with echelle (or echellette) spectrographs and the detectability of strong Mg II doublets. Only a larger sample of such high-resolution data will shed some light on this matter.
|
[
"Physics Archive->astro-ph->astro-ph.CO"
] | 2012-11-28T06:28:27Z |
nucl-th/0111042
|
Renormalization Group Equation for Low Momentum Effective Nuclear Interactions
|
We consider two nonperturbative methods originally used to derive shell model effective interactions in nuclei. These methods have been applied to the two nucleon sector to obtain an energy independent effective interaction V_{low k}, which preserves the low momentum half-on-shell T matrix and the deuteron pole, with a sharp cutoff imposed on all intermediate state momenta. We show that V_{low k} scales with the cutoff precisely as one expects from renormalization group arguments. This result is a step towards reformulating traditional model space many-body calculations in the language of effective field theories and the renormalization group. The numerical scaling properties of V_{low k} are observed to be in excellent agreement with our exact renormalization group equation.
|
[
"Physics Archive->nucl->nucl-th"
] | 2001-11-13T21:26:04Z |
1903.06037
|
On the invalidity of "negative mass" description of the dark sector
|
It is shown that the concept of "negative mass" introduced by Farnes (2018) to describe the dark sector within a unifying theory with the negative cosmological constant contradicts both the essence of the General Relativity and the available observational data. A viable model with modified weak-field General Relativity is mentioned.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->gr-qc"
] | 2019-03-13T14:45:09Z |
1003.3319
|
Weyl-Titchmarsh type formula for discrete Schroedinger operator with Wigner-von Neumann potential
|
We consider discrete Schroedinger operator J with Wigner-von Neumann potential not belonging to l^2. We find asymptotics of orthonormal polynomials associated to J. We prove the Weyl-Titchmarsh type formula, which relates the spectral density of J to a coefficient in asymptotics of orthonormal polynomials.
|
[
"Mathematics Archive->math.SP"
] | 2010-03-17T08:23:06Z |
1904.10947
|
On the Contributions of Visual and Textual Supervision in Low-Resource Semantic Speech Retrieval
|
Recent work has shown that speech paired with images can be used to learn semantically meaningful speech representations even without any textual supervision. In real-world low-resource settings, however, we often have access to some transcribed speech. We study whether and how visual grounding is useful in the presence of varying amounts of textual supervision. In particular, we consider the task of semantic speech retrieval in a low-resource setting. We use a previously studied data set and task, where models are trained on images with spoken captions and evaluated on human judgments of semantic relevance. We propose a multitask learning approach to leverage both visual and textual modalities, with visual supervision in the form of keyword probabilities from an external tagger. We find that visual grounding is helpful even in the presence of textual supervision, and we analyze this effect over a range of sizes of transcribed data sets. With ~5 hours of transcribed speech, we obtain 23% higher average precision when also using visual supervision.
|
[
"Computer Science Archive->cs.CL",
"Computer Science Archive->cs.SD",
"Electrical Engineering and Systems Science Archive->eess.AS"
] | 2019-04-24T17:44:06Z |
1402.5554
|
The flat closing problem for buildings
|
Using the notion of a strongly regular hyperbolic automorphism of a locally finite Euclidean building, we prove that any (not necessarily discrete) closed, co-compact subgroup of the type-preserving automorphisms group of a locally finite general non-spherical building contains a compact-by-Z^d subgroup, where d is the dimension of a maximal flat.
|
[
"Mathematics Archive->math.GR"
] | 2014-02-22T21:36:56Z |
2302.01193
|
Imitating careful experts to avoid catastrophic events
|
RL is increasingly being used to control robotic systems that interact closely with humans. This interaction raises the problem of safe RL: how to ensure that a RL-controlled robotic system never, for instance, injures a human. This problem is especially challenging in rich, realistic settings where it is not even possible to clearly write down a reward function which incorporates these outcomes. In these circumstances, perhaps the only viable approach is based on IRL, which infers rewards from human demonstrations. However, IRL is massively underdetermined as many different rewards can lead to the same optimal policies; we show that this makes it difficult to distinguish catastrophic outcomes (such as injuring a human) from merely undesirable outcomes. Our key insight is that humans do display different behaviour when catastrophic outcomes are possible: they become much more careful. We incorporate carefulness signals into IRL, and find that they do indeed allow IRL to disambiguate undesirable from catastrophic outcomes, which is critical to ensuring safety in future real-world human-robot interactions.
|
[
"Computer Science Archive->cs.LG",
"Computer Science Archive->cs.RO"
] | 2023-02-02T16:19:13Z |
1206.4255
|
\'Etoiles and Valuations
|
We establish some properties of \'etoiles and associated valuations over complex analytic spaces, showing that Abhyankar's inequality holds. We give some examples of pathological behavior of these valuations. We prove a regularization theorem for complex analytic morphisms.
|
[
"Mathematics Archive->math.AG",
"Mathematics Archive->math.CV"
] | 2012-06-19T16:28:09Z |
1807.00571
|
The Interplay between Lexical Resources and Natural Language Processing
|
Incorporating linguistic, world and common sense knowledge into AI/NLP systems is currently an important research area, with several open problems and challenges. At the same time, processing and storing this knowledge in lexical resources is not a straightforward task. This tutorial proposes to address these complementary goals from two methodological perspectives: the use of NLP methods to help the process of constructing and enriching lexical resources and the use of lexical resources for improving NLP applications. Two main types of audience can benefit from this tutorial: those working on language resources who are interested in becoming acquainted with automatic NLP techniques, with the end goal of speeding and/or easing up the process of resource curation; and on the other hand, researchers in NLP who would like to benefit from the knowledge of lexical resources to improve their systems and models. The slides of the tutorial are available at https://bitbucket.org/luisespinosa/lr-nlp/
|
[
"Computer Science Archive->cs.CL"
] | 2018-07-02T09:53:50Z |
2305.19148
|
Mitigating Label Biases for In-context Learning
|
Various design settings for in-context learning (ICL), such as the choice and order of the in-context examples, can bias a model toward a particular prediction without being reflective of an understanding of the task. While many studies discuss these design choices, there have been few systematic investigations into categorizing them and mitigating their impact. In this work, we define a typology for three types of label biases in ICL for text classification: vanilla-label bias, context-label bias, and domain-label bias (which we conceptualize and detect for the first time). Our analysis demonstrates that prior label bias calibration methods fall short of addressing all three types of biases. Specifically, domain-label bias restricts LLMs to random-level performance on many tasks regardless of the choice of in-context examples. To mitigate the effect of these biases, we propose a simple bias calibration method that estimates a language model's label bias using random in-domain words from the task corpus. After controlling for this estimated bias when making predictions, our novel domain-context calibration significantly improves the ICL performance of GPT-J and GPT-3 on a wide range of tasks. The gain is substantial on tasks with large domain-label bias (up to 37% in Macro-F1). Furthermore, our results generalize to models with different scales, pretraining methods, and manually-designed task instructions, showing the prevalence of label biases in ICL.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.CL",
"Computer Science Archive->cs.LG"
] | 2023-05-28T15:37:39Z |
2210.11117
|
Associated Permutations of Complete Non-Ambiguous Trees
|
This paper explores connections between complete non-ambiguous trees (CNATs), and permutations. We prove a necessary and sufficient condition for a collection of vertices to be the set of leaves of at least one CNAT, and use this to calculate the number of such collections which are the set of leaves of exactly one CNAT. We give a bijection between tree-like tableaux, in which vertices are placed into a Ferrers diagram, and a certain type of CNAT. This is used to establish and solve a recurrence relation for the number of tree-like tableaux of a given size without occupied corners, proving a conjecture by Laborde-Zubieta. We end by establishing a row/column swapping operation on CNATs, and identify new areas for research.
|
[
"Mathematics Archive->math.CO"
] | 2022-10-20T09:21:36Z |
2101.01034
|
Sidon sets for linear forms
|
Let $\varphi(x_1,\ldots, x_h) = c_1 x_1 + \cdots + c_h x_h $ be a linear form with coefficients in a field $\mathbf{F}$, and let $V$ be a vector space over $\mathbf{F}$. A nonempty subset $A$ of $V$ is a $\varphi$-Sidon set if, for all $h$-tuples $(a_1,\ldots, a_h) \in A^h$ and $ (a'_1,\ldots, a'_h) \in A^h$, the relation $\varphi(a_1,\ldots, a_h) = \varphi(a'_1,\ldots, a'_h)$ implies $(a_1,\ldots, a_h) = (a'_1,\ldots, a'_h)$. There exist infinite Sidon sets for the linear form $\varphi$ if and only if the set of coefficients of $\varphi$ has distinct subset sums. In a normed vector space with $\varphi$-Sidon sets, every infinite sequence of vectors is asymptotic to a $\varphi$-Sidon set of vectors. Results on $p$-adic perturbations of $\varphi$-Sidon sets of integers and bounds on the growth of $\varphi$-Sidon sets of integers are also obtained.
|
[
"Mathematics Archive->math.CO",
"Mathematics Archive->math.NT"
] | 2021-01-04T15:33:58Z |
0906.4593
|
Ground State of Fermions in a 1D Trap with $\delta$ Function Interaction
|
The ground state of Fermions in a 1D trap with $\delta$ function interaction is studied mathematically with group theory ideas.
|
[
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2009-06-25T02:33:49Z |
1305.7510
|
Inequalities for the one-dimensional analogous of the Coulomb potential
|
In this paper our aim is to present some monotonicity and convexity properties for the one dimensional regularization of the Coulomb potential, which has applications in the study of atoms in magnetic fields and which is in fact a particular case of the Tricomi confluent hypergeometric function. Moreover, we present some Tur\'an type inequalities for the function in the question and we deduce from these inequalities some new tight upper bounds for the Mills ratio of the standard normal distribution.
|
[
"Mathematics Archive->math.CA"
] | 2013-05-31T19:11:33Z |
1408.1242
|
Unifying order structures for Colombeau algebras
|
We define a general notion of set of indices which, using concepts from pre-ordered sets theory, permits to unify the presentation of several Colombeau-type algebras of nonlinear generalized functions. In every set of indices it is possible to generalize Landau's notion of big-O such that its usual properties continue to hold. Using this generalized notion of big-O, these algebras can be formally defined the same way as the special Colombeau algebra. Finally, we examine the scope of this formalism and show its effectiveness by applying it to the proof of the pointwise characterization in Colombeau algebras.
|
[
"Mathematics Archive->math.FA"
] | 2014-08-06T10:57:30Z |
2207.03089
|
Twisted Koecher-Maass series of the Ikeda type lift for the exceptional group of type $E_{7,3}$
|
We compute the twisted Koecher-Maass series of the first and second kind of the Ikeda type lift for the exceptional group of type $E_{7,3}$. As an application, we obtain their rationality result.
|
[
"Mathematics Archive->math.NT"
] | 2022-07-07T05:06:04Z |
1412.5117
|
Lifting degenerate neutrino masses, threshold corrections and maximal mixing
|
In the scenario with degenerate neutrino masses at tree-level, we show how threshold corrections with either non-trivial or trivial mixing at tree-level have the power to generate the observed deviations from a degenerate spectrum. Moreover, it is possible to also generate the mixing fully radiatively when there is trivial mixing at tree-level. We give a brief overview over the topic and discuss the outcome of threshold corrections for degenerate neutrino masses in a supersymmetric model. A detailed description can be found in [arXiv:1412.4585].
|
[
"Physics Archive->hep->hep-ph"
] | 2014-12-16T18:42:56Z |
1411.5880
|
A sheet on deformable sphere: "wrinklogami" patterns suppress curvature-induced delamination
|
The adhesion of a stiff film onto a curved substrate often generates elastic stresses in the film that eventually give rise to its delamination. Here we predict that delamination of very thin films can be dramatically suppressed through tiny, smooth deformations of the substrate, dubbed here "wrinklogami", that barely affect the macroscale topography. This "pro-lamination" effect reflects a surprising capability of smooth wrinkles to suppress compression in elastic films even when spherical or other doubly-curved topography is imposed, in a similar fashion to origami folds that enable construction of curved structures from an unstretchable paper. We show that the emergence of a wrinklogami pattern signals a nontrivial isometry of the sheet to its planar, undeformed state, in the doubly asymptotic limit of small thickness and weak tensile load exerted by the adhesive substrate. We explain how such an "asymptotic isometry" concept broadens the standard usage of isometries for describing the response of elastic sheets to geomertric constraints and mechanical loads.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci",
"Physics Archive->cond-mat->cond-mat.soft"
] | 2014-11-20T03:03:54Z |
2006.03691
|
$H$-kernels in $H$-colored digraphs without $(\xi_{1}, \xi, \xi_{2})$-$H$-subdivisions of $\overrightarrow{C_{3}}$
|
Let $H$ be a digraph possibly with loops and $D$ a digraph without loops with a coloring of its arcs $c:A(D) \rightarrow V(H)$ ($D$ is said to be an $H$-colored digraph). A directed path $W$ in $D$ is said to be an $H$-path if and only if the consecutive colors encountered on $W$ form a directed walk in $H$. A subset $N$ of vertices of $D$ is said to be an $H$-kernel if (1) for every pair of different vertices in $N$ there is no $H$-path between them and (2) for every vertex $u$ in V($D$)$\setminus$$N$ there exists an $H$-path in $D$ from $u$ to $N$. Under this definition an $H$-kernel is a kernel whenever $A(H)=\emptyset$. The color-class digraph $\mathscr{C}_C$($D$) of $D$ is the digraph whose vertices are the colors represented in the arcs of $D$ and ($i$,$j$) $\in$ $A$($\mathscr{C}_C$($D$)) if and only if there exist two arcs, namely ($u$,$v$) and ($v$,$w$) in $D$, such that ($u$,$v$) has color $i$ and ($v$,$w$) has color $j$. Since not every $H$-colored digraph has an $H$-kernel and $V(\mathscr{C}_C(D))= V(H)$, the natural question is: what structural properties of $\mathscr{C}_C(D)$, with respect to the $H$-coloring, imply that $D$ has an $H$-kernel? In this paper we investigate the problem of the existence of an $H$-kernel by means of a partition $\xi$ of $V(H)$ and a partition \{$\xi_1$, $\xi_2$\} of $\xi$. We establish conditions on the directed cycles and the directed paths of the digraph $D$, with respect to the partition \{$\xi_1$, $\xi_2$\}. In particular we pay attention to some subestructures produced by the partitions $\xi$ and \{$\xi_1$, $\xi_2$\}, namely $(\xi_{1}, \xi, \xi_{2})$-$H$-subdivisions of $\overrightarrow{C_{3}}$ and $(\xi_{1}, \xi, \xi_{2})$-$H$-subdivisions of $\overrightarrow{P_{3}}$. We give some examples which show that each hypothesis in the main result is tight.
|
[
"Mathematics Archive->math.CO"
] | 2020-06-05T21:11:45Z |
2002.06919
|
Influence of electron cooling on the polarization lifetime of a horizontally polarized storage ring beam
|
A previous publication has shown that the in-plane polarization (IPP) component of a polarized 0.97-GeV/c deuteron beam in the COSY storage ring may acquire a polarization half-life in excess of 1000 s through a combination of beam bunching, electron cooling (prior to any spin manipulation), sextupole field adjustment, and a limitation of the beam intensity. This paper documents further tests pointing to additional gains in the IPP lifetime if cooling is active throughout the beam store.
|
[
"Physics Archive->physics->physics.acc-ph"
] | 2020-02-17T12:48:15Z |
quant-ph/9912046
|
Entanglement of Atomic Ensembles by Trapping Correlated Photon States
|
We describe a general technique that allows for an ideal transfer of quantum correlations between light fields and metastable states of matter. The technique is based on trapping quantum states of photons in coherently driven atomic media, in which the group velocity is adiabatically reduced to zero. We discuss possible applications such as quantum state memories, generation of squeezed atomic states, preparation of entangled atomic ensembles and quantum information processing.
|
[
"Physics Archive->quant-ph"
] | 1999-12-10T01:00:20Z |
2201.02860
|
Local Gyrokinetic Collisional Theory of the Ion-Temperature Gradient Mode
|
We present a study of the linear properties of ion temperature gradient (ITG) modes with collisions modelled by the linearized gyrokinetic (GK) Coulomb collision operator (Frei et al. 2021) in the local limit. The study is based on a Hermite-Laguerre polynomial expansion of the perturbed ion distribution function applied to the linearized GK Boltzmann equation, yielding a hierarchy of coupled equations for the expansion coefficients, referred to as gyro-moments. We explore analytically the collisionless and high-collisional limits of the gyro-moment hierarchy. Parameter scans revealing the dependence of the ITG growth rate on the collisionality are reported, showing strong damping at small scales as the collisionality increases. These properties are compared with the predictions based on the Sugama, the momentum-conserving pitch-angle scattering, the Hirshman- Sigmar-Clarke, and the Daugherty collision operators. The importance of finite Larmor radius (FLR) terms in the collision operators is pointed out by the appearance of a short wavelength (SW) ITG branch when collisional FLR terms are neglected, this branch being completely suppressed by collisional FLR effects. We demonstrate that energy diffusion is important at high collisionality and small scale lengths and that, among the collision operators considered in this work, the GK Sugama collision operator yields, in general, the smallest deviation on the ITG growth rate compared to the GK Coulomb collision operator. Convergence studies of the gyro-moment method are reported.
|
[
"Physics Archive->physics->physics.plasm-ph"
] | 2022-01-08T16:49:52Z |
1210.7775
|
MHD Modeling of a Disk-Wind from a High-Mass Protobinary: the case of Orion Source I
|
Very long baseline interferometry (VLBI) observations of SiO masers in Orion Source I has enabled for the first time to resolve the outflow from a high-mass protostar in the launch and collimation region. Therefore, Source I provides a unique laboratory to study mass-loss and mass-accretion in a high-mass protostar. We numerically simulate the dynamics of the disk-wind inside 100 AU from Source I. This enables us to investigate the balance of different forces (gravitational, magnetic, thermal) regulating gas dynamics in massive star formation. In this work, we adopt magnetohydrodynamic (MHD) disk-wind models to explain the observed properties of the disk-wind from Orion Source I. The central source is assumed to be a binary composed of two 10\,$\msun$ stars in a circular orbit with an orbital separation of 7 AU. High resolution ideal MHD wind launching simulations (which prescribe disk as a boundary) are performed using the PLUTO code. The simulations are allowed to run until a steady state is obtained. MHD driven disk-wind provides a consistent model for the wide-angle flow from Source I probed by SiO masers, reproducing the bipolar morphology, the velocity amplitude and rotational profile, the physical conditions, and the magnetic field strength.
|
[
"Physics Archive->astro-ph->astro-ph.SR"
] | 2012-10-29T19:01:23Z |
1111.7143
|
The product of matrix subspaces
|
In factoring matrices into the product of two matrices operations are typically performed with elements restricted to matrix subspaces. Such modest structural assumptions are realistic, for example, in large scale computations. This paper is concerned with analyzing associated matrix geometries. Curvature of the product of two matrix subspaces is assessed. As an analogue of the internal Zappa-Sz\'ep product of a group, the notion of factorizable matrix subspace arises. Interpreted in this way, several classical instances are encompassed by this structure. The Craig-Sakamoto theorem fits naturally into this framework.
|
[
"Mathematics Archive->math.FA",
"Mathematics Archive->math.OA"
] | 2011-11-30T12:43:21Z |
1807.02944
|
A short proof for tc(K) = 4
|
We show a method to determine topological complexity from the fibrewise view point, which provides an alternative proof for tc(K) = 4, where K denotes Klein bottle.
|
[
"Mathematics Archive->math.AT"
] | 2018-07-09T05:12:05Z |
1904.08193
|
Study of memory effect in an EOQ model for completely backlogged demand during shortage
|
The most commonly developed inventory models are the classical economic order quantity model, is governed by the integer order differential equations. We want to come out from the traditional thought i.e. classical order inventory model where the memory phenomena are absent. Here, we want to incorporate the memory effect that is based on the fact economic agents remember the history of changes of exogenous and endogenous variables. In this paper, we have proposed and solved a fractional order EOQ model with constant demand rate where the demand is fully backlogged during shortage time. Finally, a numerical example has been illustrated for this model to show the memory dependency of the system. The numerical example clears that for the considered system the profit is maximum in long memory affected system compared to the low memory affected or memory less system.
|
[
"Mathematics Archive->math.OC"
] | 2019-04-17T11:24:57Z |
0712.0333
|
Application of the anisotropic bond model to second-harmonic generation from amorphous media
|
As a step toward analyzing second-harmonic generation (SHG) from crystalline Si nanospheres in glass, we develop an anisotropic bond model (ABM) that expresses SHG in terms of physically meaningful parameters and provides a detailed understanding of the basic physics of SHG on the atomic scale. Nonlinear-optical (NLO) responses are calculated classically via the four fundamental steps of optics: evaluate the local field at a given bond site, solve the force equation for the acceleration of the charge, calculate the resulting radiation, then superpose the radiation from all charges. The ABM goes beyond previous bond models by including the complete set of underlying contributions: retardation (RD), spatial-dispersion (SD), and magnetic (MG) effects, in addition to the anharmonic restoring force acting on the bond charge. We apply the ABM to obtain analytic expressions for SHG from amorphous materials under Gaussian-beam excitation. These materials represent an interesting test case not only because they are ubiquitous but also because the anharmonic-force contribution that dominates the SHG response of crystalline materials and ordered interfaces vanishes by symmetry. Using the paraxial-ray approximation, we reduce the results to the isotropic case in two limits, that where the linear restoring force dominates (glasses), and that where it is absent (metals). Both forward- and backscattering geometries are discussed. Estimated signal strengths and conversion efficiencies for fused silica appear to be in general agreement with data, where available. Predictions are made that allow additional critical tests of these results.
|
[
"Physics Archive->physics->physics.optics"
] | 2007-12-03T16:06:54Z |
1904.07783
|
Internal friction controls active ciliary oscillations near the instability threshold
|
Ciliary oscillations driven by molecular motors cause fluid motion at micron scale. Stable oscillations require a substantial source of dissipation to balance the energy input of motors. Conventionally, it stems from external fluid. We show, in contrast, that external fluid friction is negligible compared to internal elastic stress through a simultaneous measurement of motion and flow field of an isolated and active Chlamydomonas cilium beating near the instability threshold. Consequently, internal friction emerges as the sole source of dissipation for ciliary oscillations. We combine these experimental insights with theoretical modeling of active filaments to show that an instability to oscillations takes place when active stresses are strain softening and shear thinning. Together, our results reveal a counterintuitive mechanism of ciliary beating and provide a general experimental and theoretical methodology to analyze other active filaments, both biological and synthetic ones.
|
[
"Physics Archive->cond-mat->cond-mat.soft"
] | 2019-04-16T16:07:43Z |
1507.00211
|
A Note on Holographic Non-Relativistic Goldstone Bosons
|
We consider a holographic set-up where relativistic invariance is broken by a chemical potential, and a non-abelian internal symmetry is broken spontaneously. We use the tool of holographic renormalization in order to infer what can be learned purely by analytic boundary considerations. We find that the expected Ward identities are correctly reproduced. In particular, we obtain the identity which implies the non-commutation of a pair of broken charges, which leads to the presence of Goldstone bosons with quadratic dispersion relations.
|
[
"Physics Archive->hep->hep-th"
] | 2015-07-01T12:42:45Z |
gr-qc/9701018
|
Semiclassical quantum states for black holes
|
I discuss the semiclassical approximation for the Wheeler-DeWitt equation when applied to the CGHS model and spherically symmetric gravity. Special attention is devoted to the issues of Hawking radiation, decoherence of semiclassical states, and black hole entropy.
|
[
"Physics Archive->gr-qc"
] | 1997-01-10T16:29:55Z |
2203.15317
|
Agreement or Disagreement in Noise-tolerant Mutual Learning?
|
Deep learning has made many remarkable achievements in many fields but suffers from noisy labels in datasets. The state-of-the-art learning with noisy label method Co-teaching and Co-teaching+ confronts the noisy label by mutual-information between dual-network. However, the dual network always tends to convergent which would weaken the dual-network mechanism to resist the noisy labels. In this paper, we proposed a noise-tolerant framework named MLC in an end-to-end manner. It adjusts the dual-network with divergent regularization to ensure the effectiveness of the mechanism. In addition, we correct the label distribution according to the agreement between dual-networks. The proposed method can utilize the noisy data to improve the accuracy, generalization, and robustness of the network. We test the proposed method on the simulate noisy dataset MNIST, CIFAR-10, and the real-world noisy dataset Clothing1M. The experimental result shows that our method outperforms the previous state-of-the-art method. Besides, our method is network-free thus it is applicable to many tasks. Our code can be found at https://github.com/JiarunLiu/MLC.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.CV",
"Computer Science Archive->cs.LG"
] | 2022-03-29T08:00:51Z |
nlin/0003028
|
Generalized Flows, Intrinsic Stochasticity, and Turbulent Transport
|
The study of passive scalar transport in a turbulent velocity field leads naturally to the notion of generalized flows which are families of probability distributions on the space of solutions to the associated ODEs, which no longer satisfy the uniqueness theorem for ODEs. Two most natural regularizations of this problem, namely the regularization via adding small molecular diffusion and the regularization via smoothing out the velocity field are considered. White-in-time random velocity fields are used as an example to examine the variety of phenomena that take place when the velocity field is not spatially regular. Three different regimes characterized by their degrees of compressibility are isolated in the parameter space. In the regime of intermediate compressibility, the two different regularizations give rise to two different scaling behavior for the structure functions of the passive scalar. Physically this means that the scaling depends on Prandtl number. In the other two regimes the two different regularizations give rise to the same generalized flows even though the sense of convergence can be very different. The ``one force, one solution'' principle and the existence and uniqueness of an invariant measure are established for the scalar field in the weakly compressible regime, and for the difference of the scalar in the strongly compressible regime.
|
[
"Physics Archive->nlin->nlin.CD"
] | 2000-03-10T15:25:50Z |
2305.09499
|
Energy and Angle Dependence of Neutrino Scattering Rates in Proto-Neutron Star and Supernova Matter within Skyrme RPA
|
Supernova explosions are the most powerful neutrino sources. The neutrino emission is also the dominating cooling mechanism for a proto-neutron star, whose interior is mainly composed of extremely dense and hot nuclear matter. Neutrino transport is an essential part of the simulation of these phenomena, and modern codes are able to implement inelastic neutrino scattering and also to some extent its angle distribution. We therefore study the energy and angle dependence of neutrino scattering rates in proto-neutron star and supernova matter with the full Skyrme RPA response functions. We confirm earlier findings obtained in the Landau approximation that the RPA reduces neutrino scattering, but the detailed differential scattering rates in hot and dense matter depend sensitively on the adopted interaction. The scattering angle distribution is different for different interactions because it depends strongly on the neutron Fermi velocity. We also find that many Skyrme interactions present an unphysical feature that the Fermi velocity of neutrons exceeds the speed of light already at relatively low densities.
|
[
"Physics Archive->nucl->nucl-th"
] | 2023-05-16T14:52:54Z |
1608.00223
|
Entropy production inequalities for the Kac Walk
|
Mark Kac introduced what is now called 'the Kac Walk' with the aim of investigating the spatially homogeneous Boltzmann equation by probabilistic means. Much recent work, discussed below, on Kac's program has run in the other direction: using recent results on the Boltzmann equation, or its one-dimensional analog, the non-linear Kac-Boltzmann equation, to prove results for the Kac Walk. Here we investigate new functional inequalities for the Kac Walk pertaining to entropy production, and introduce a new form of `chaoticity'. We then show how these entropy production inequalities imply entropy production inequalities for the Kac-Boltzmann equation. This results validate Kac's program for proving results on the non-linear Boltzmann equation via analysis of the Kac Walk, and they constitute a partial solution to the `Almost' Cercignani Conjecture on the sphere.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->math-ph"
] | 2016-07-31T14:44:26Z |
astro-ph/9911019
|
Luminous Infrared Galaxies. III. Multiple Merger, Extended Massive Star Formation, Galactic-Wind and Nuclear-Inflow in NGC 3256
|
We find in a detailed morphological study (at 15 pc resolution) that the extended massive star formation process, shows: (i) extended triple asymmetrical spiral arms structure (r = 5 kpc); and (ii) the spiral arms emanate from three different nuclei. The main optical nucleus shows a small spiral-disk (r = 500 pc) which is a continuation of the external one and reach the very nucleus. And this very nucleus shows blue elongate structure (63 pc x 30 pc), and luminous blue star cluster properties. We study the kinematics of this system and present a detailed Halpha velocity field for the central region (r = 5 kpc). In the main optical nucleus we found a clear "outflow component" associated to galactic-winds and a "inflow radial motion" (in the spiral-disk nuclear structure, r = 700 pc). In addition we detected the outflow component in the central and external regions (r < 5-6 kpc), with a very wide opening angle of 140. We found that the mean value of the inflow region (at PA = 80) is practically perpendicular to the axis of the bipolar outflow (at PA = 160). We analyze in detail the physical conditions in the giant H II regions located in the asymmetric spiral arms, the two main optical nuclei, and the outflow component. In the central region (r = 5-6 kpc) we detected that the nuclear starburst and the extended giant H II regions have very similar properties. We suggest that the interaction between dynamical effects, the galactic--wind (outflow), low-energy cosmic rays, and the molecular+ionized gas (probably in the inflow phase) could be the possible mechanism that generate the "similar extended properties in the massive star formation, at scale of 5-6 kpc!". We analyze for NGC3256 the possible evolution from luminous IR galaxy to QSOs.
|
[
"Physics Archive->astro-ph"
] | 1999-11-02T18:40:09Z |
cond-mat/9707193
|
Relaxation Spectra at the Glass Transition: Origin of Power Laws
|
We propose a simple dynamical model of the glass transition based on the results from a non-randomly frustrated spin model which is known to form a glassy state below a characteristic quench temperature. The model is characterized by a multi-valleyed free-energy surface which is modulated by an overall curvature. The transition associated with the vanishing of this overall curvature is reminiscent of the glass transition. In particular, the frequency-dependent response evolves from a Debye relaxation peak to a function whose high-frequency behavior is characterized by a non-trivial power law. We present both an analytical form for the response function and numerical results from Langevin simulations.
|
[
"Physics Archive->cond-mat->cond-mat.dis-nn",
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | 1997-07-18T15:18:52Z |
cond-mat/9404008
|
New perturbation theory of low-dimensional quantum liquids I: the pseudoparticle operator basis
|
We introduce a new operator algebra for the description of the low-energy physics of one-dimensional, integrable, multicomponent quantum liquids. Considering the particular case of the Hubbard chain in a constant external magnetic field and with varying chemical potential, we show that at low energy its Bethe-ansatz solution can be interpreted in terms of the new {\it pseudoparticle operator algebra}. Our algebraic approach provides a concise interpretation of and justification for several recent studies of low-energy excitations and transport which have been based on detailed analyses of specific Bethe-ansatz eigenfunctions and eigenenergies. A central point is that the {\it exact ground state} of the interacting many-electron problem is the non-interacting pseudoparticle ground state. Furthermore, in the pseudoparticle basis, the quantum problem becomes perturbative, {\it i.e.}, the two-pseudoparticle forward-scattering vertices and amplitudes do not diverge, and one can define a many-pseudoparticle perturbation theory. We write the general quantum-liquid Hamiltonian in the new basis and show that the pseudoparticle-perturbation theory leads, in a natural way, to the generalized Landau-liquid approach.
|
[
"Physics Archive->cond-mat"
] | 1994-04-06T19:01:00Z |
hep-ph/0005092
|
Semi-inclusive hadron-hadron transverse spin asymmetries and their implication for polarized DIS
|
We discuss a possible explanation of the 25 year old mystery of the large transverse spin asymmetries found in many semi-inclusive hadron-hadron reactions. We obtain the first reliable information about the transverse polarized quark densities Delta_T q(x) and we find surprising implications for the usual, longitudinal, polarized DIS. The plan of the presentation is as follows: 1) A brief reminder about the internal structure of the nucleon. 2) The transverse asymmetries. 3) Why it is so difficult to explain the asymmetries. 4) Failure and then success using a new soft mechanism. 5) implications for polarized DIS.
|
[
"Physics Archive->hep->hep-ph"
] | 2000-05-10T15:27:17Z |
1802.07439
|
Constant Factor Approximation Algorithm for Weighted Flow Time on a Single Machine in Pseudo-polynomial time
|
In the weighted flow-time problem on a single machine, we are given a set of n jobs, where each job has a processing requirement p_j, release date r_j and weight w_j. The goal is to find a preemptive schedule which minimizes the sum of weighted flow-time of jobs, where the flow-time of a job is the difference between its completion time and its released date. We give the first pseudo-polynomial time constant approximation algorithm for this problem. The running time of our algorithm is polynomial in n, the number of jobs, and P, which is the ratio of the largest to the smallest processing requirement of a job. Our algorithm relies on a novel reduction of this problem to a generalization of the multi-cut problem on trees, which we call the Demand Multi-Cut problem. Even though we do not give a constant factor approximation algorithm for the Demand Multi-Cut problem on trees, we show that the specific instances of Demand Multi-Cut obtained by reduction from weighted flow-time problem instances have more structure in them, and we are able to employ techniques based on dynamic programming. Our dynamic programming algorithm relies on showing that there are near optimal solutions which have nice smoothness properties, and we exploit these properties to reduce the size of DP table.
|
[
"Computer Science Archive->cs.DS"
] | 2018-02-21T06:36:26Z |
2102.01886
|
Learning Diverse-Structured Networks for Adversarial Robustness
|
In adversarial training (AT), the main focus has been the objective and optimizer while the model has been less studied, so that the models being used are still those classic ones in standard training (ST). Classic network architectures (NAs) are generally worse than searched NAs in ST, which should be the same in AT. In this paper, we argue that NA and AT cannot be handled independently, since given a dataset, the optimal NA in ST would be no longer optimal in AT. That being said, AT is time-consuming itself; if we directly search NAs in AT over large search spaces, the computation will be practically infeasible. Thus, we propose a diverse-structured network (DS-Net), to significantly reduce the size of the search space: instead of low-level operations, we only consider predefined atomic blocks, where an atomic block is a time-tested building block like the residual block. There are only a few atomic blocks and thus we can weight all atomic blocks rather than find the best one in a searched block of DS-Net, which is an essential trade-off between exploring diverse structures and exploiting the best structures. Empirical results demonstrate the advantages of DS-Net, i.e., weighting the atomic blocks.
|
[
"Computer Science Archive->cs.CV",
"Computer Science Archive->cs.LG"
] | 2021-02-03T05:52:11Z |
cond-mat/0411666
|
Collective traffic-like movement of ants on a trail: dynamical phases and phase transitions
|
The traffic-like collective movement of ants on a trail can be described by a stochastic cellular automaton model. We have earlier investigated its unusual flow-density relation by using various mean field approximations and computer simulations. In this paper, we study the model following an alternative approach based on the analogy with the zero range process, which is one of the few known exactly solvable stochastic dynamical models. We show that our theory can quantitatively account for the unusual non-monotonic dependence of the average speed of the ants on their density for finite lattices with periodic boundary conditions. Moreover, we argue that the model exhibits a continuous phase transition at the critial density only in a limiting case. Furthermore, we investigate the phase diagram of the model by replacing the periodic boundary conditions by open boundary conditions.
|
[
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | 2004-11-26T08:49:18Z |
astro-ph/0311528
|
The Luminosity Function of Lyman Alpha Emitters at Redshift z~5.7
|
We report results of a deep wide-field narrowband survey for redshift z~5.7 Ly alpha emitters carried out with SuprimeCam on Subaru 8.3-m telescope. Deep narrowband imaging of the SSA22 field through a 120 A bandpass filter centered at 8150 A was combined with deep multicolor RIz' SuprimeCam broadband imaging, and BVRZ imaging taken with CFHT's CFH12K camera to select high-redshift galaxy candidates. Spectroscopic observations were made using the new wide-field multi-object DEIMOS spectrograph on Keck for 22 of the 26 candidate objects. Eighteen objects were identified as z~5.7 Lyman alpha emitters, and a further nineteenth candidate was identified based on an LRIS spectrum. At the 3.3 A resolution of the DEIMOS spectra the asymmetric profile for Ly alpha emission with its steep blue fall-off can be clearly seen. We use this to describe the distribution of equivalent widths and the continuum color break properties for z~5.7 Ly alpha galaxies compared with foreground objects. The large majority (>75%) of Ly alpha lines have rest frame equivalent widths less than 240 A and can be understood in terms of young star forming galaxies with a Salpeter initial mass function for the stars. With narrowband selection criteria of I-N > 0.7 and N<25.05 (AB mags) we find a surface density of Ly alpha emitters of 0.03 per square arcminute per (deltaz=0.1) to a limiting flux just under 2e-17 erg/cm2/s. The luminosity function of the Ly alpha emitters is similar to that at lower redshifts to the lowest measurable luminosity of 1e43 ergs/s as is the universal star formation rate based on their continuum properties. We note that the objects are highly structured in both spatial and spectral properties on the angular scale of the fields (~60 Mpc), and that multiple fields will have to be averaged to accurately measure their ensemble properties.
|
[
"Physics Archive->astro-ph"
] | 2003-11-24T05:10:40Z |
1201.1684
|
The Three-User Finite-Field Multi-Way Relay Channel with Correlated Sources
|
This paper studies the three-user finite-field multi-way relay channel, where the users exchange messages via a relay. The messages are arbitrarily correlated, and the finite-field channel is linear and is subject to additive noise of arbitrary distribution. The problem is to determine the minimum achievable source-channel rate, defined as channel uses per source symbol needed for reliable communication. We combine Slepian-Wolf source coding and functional-decode-forward channel coding to obtain the solution for two classes of source and channel combinations. Furthermore, for correlated sources that have their common information equal their mutual information, we propose a new coding scheme to achieve the minimum source-channel rate.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2012-01-09T03:26:47Z |
2110.10313
|
Certified Hermite Matrices from Approximate Roots
|
Let I=<f_1, ..., f_m> be a zero dimensional radical ideal Q[x_1,...,x_n]. Assume that we are given approximations {z_1,...,z_k} in C^n for the common roots V(I)={xi_1,...,xi_k}. In this paper we show how to construct and certify the rational entries of Hermite matrices for I from the approximate roots {z_1, ...,z_k}. When I is non-radical, we give methods to construct and certify Hermite matrices for the radical of I from approximate roots. Furthermore, we use signatures of these Hermite matrices to give rational certificates of non-negativity of a given polynomial over a (possibly positive dimensional) real variety, as well as certificates that there is a real root within an epsilon distance from a given point z in Q^n.
|
[
"Mathematics Archive->math.AG"
] | 2021-10-19T23:44:19Z |
1801.08747
|
Weakly Supervised Object Detection with Pointwise Mutual Information
|
In this work a novel approach for weakly supervised object detection that incorporates pointwise mutual information is presented. A fully convolutional neural network architecture is applied in which the network learns one filter per object class. The resulting feature map indicates the location of objects in an image, yielding an intuitive representation of a class activation map. While traditionally such networks are learned by a softmax or binary logistic regression (sigmoid cross-entropy loss), a learning approach based on a cosine loss is introduced. A pointwise mutual information layer is incorporated in the network in order to project predictions and ground truth presence labels in a non-categorical embedding space. Thus, the cosine loss can be employed in this non-categorical representation. Besides integrating image level annotations, it is shown how to integrate point-wise annotations using a Spatial Pyramid Pooling layer. The approach is evaluated on the VOC2012 dataset for classification, point localization and weakly supervised bounding box localization. It is shown that the combination of pointwise mutual information and a cosine loss eases the learning process and thus improves the accuracy. The integration of coarse point-wise localizations further improves the results at minimal annotation costs.
|
[
"Computer Science Archive->cs.CV"
] | 2018-01-26T10:46:43Z |
2209.06202
|
Hierarchy of topological order from finite-depth unitaries, measurement and feedforward
|
Long-range entanglement--the backbone of topologically ordered states--cannot be created in finite time using local unitary circuits, or equivalently, adiabatic state preparation. Recently it has come to light that single-site measurements provide a loophole, allowing for finite-time state preparation in certain cases. Here we show how this observation imposes a complexity hierarchy on long-range entangled states based on the minimal number of measurement layers required to create the state, which we call "shots". First, similar to Abelian stabilizer states, we construct single-shot protocols for creating any non-Abelian quantum double of a group with nilpotency class two (such as $D_4$ or $Q_8$). We show that after the measurement, the wavefunction always collapses into the desired non-Abelian topological order, conditional on recording the measurement outcome. Moreover, the clean quantum double ground state can be deterministically prepared via feedforward--gates which depend on the measurement outcomes. Second, we provide the first constructive proof that a finite number of shots can implement the Kramers-Wannier duality transformation (i.e., the gauging map) for any solvable symmetry group. As a special case, this gives an explicit protocol to prepare twisted quantum double for all solvable groups. Third, we argue that certain topological orders, such as non-solvable quantum doubles or Fibonacci anyons, define non-trivial phases of matter under the equivalence class of finite-depth unitaries and measurement, which cannot be prepared by any finite number of shots. Moreover, we explore the consequences of allowing gates to have exponentially small tails, which enables, for example, the preparation of any Abelian anyon theory, including chiral ones. This hierarchy paints a new picture of the landscape of long-range entangled states, with practical implications for quantum simulators.
|
[
"Physics Archive->cond-mat->cond-mat.str-el",
"Physics Archive->quant-ph"
] | 2022-09-13T17:55:36Z |
1410.7435
|
On the Expansion Rate, Age, and Distance of the Supernova Remnant G266.2-1.2 (Vela Jr.)
|
An analysis of Chandra ACIS data for two relatively bright and narrow portions of the northwestern rim of G266.2-1.2 (a.k.a. RX J0852.0-4622 or Vela Jr.) reveal evidence of a radial displacement of 2.40 +/- 0.56 arcsec between 2003 and 2008. The corresponding expansion rate (0.42 +/- 0.10 arcsec/yr or 13.6 +/- 4.2%/kyr) is about half the rate reported for an analysis of XMM-Newton data from a similar, but not identical, portion of the rim over a similar, but not identical, time interval (0.84 +/- 0.23 arcsec/yr, Katsuda et al. 2008a). If the Chandra rate is representative of the remnant as a whole, then the results of a hydrodynamic analysis suggest that G266.2-1.2 is between 2.4 and 5.1 kyr old if it is expanding into a uniform ambient medium (whether or not it was produced by a Type Ia or Type II event). If the remnant is expanding into the material shed by a steady stellar wind, then the age could be as much as 50% higher. The Chandra expansion rate and a requirement that the shock speed be greater than or equal to 1000 km/s yields a lower limit on the distance of 0.5 kpc. An analysis of previously-published distance estimates and constraints suggests G266.2-1.2 is no further than 1.0 kpc. This range of distances is consistent with the distance to the nearer of two groups of material in the Vela Molecular Ridge (0.7 +/- 0.2 kpc, Liseau et al. 1992) and to the Vel OB1 association (0.8 kpc, Eggen 1982).
|
[
"Physics Archive->astro-ph->astro-ph.HE"
] | 2014-10-27T21:23:03Z |
2310.19319
|
Dual-Directed Algorithm Design for Efficient Pure Exploration
|
We consider pure-exploration problems in the context of stochastic sequential adaptive experiments with a finite set of alternative options. The goal of the decision-maker is to accurately answer a query question regarding the alternatives with high confidence with minimal measurement efforts. A typical query question is to identify the alternative with the best performance, leading to ranking and selection problems, or best-arm identification in the machine learning literature. We focus on the fixed-precision setting and derive a sufficient condition for optimality in terms of a notion of strong convergence to the optimal allocation of samples. Using dual variables, we characterize the necessary and sufficient conditions for an allocation to be optimal. The use of dual variables allow us to bypass the combinatorial structure of the optimality conditions that relies solely on primal variables. Remarkably, these optimality conditions enable an extension of top-two algorithm design principle, initially proposed for best-arm identification. Furthermore, our optimality conditions give rise to a straightforward yet efficient selection rule, termed information-directed selection, which adaptively picks from a candidate set based on information gain of the candidates. We outline the broad contexts where our algorithmic approach can be implemented. We establish that, paired with information-directed selection, top-two Thompson sampling is (asymptotically) optimal for Gaussian best-arm identification, solving a glaring open problem in the pure exploration literature. Our algorithm is optimal for $\epsilon$-best-arm identification and thresholding bandit problems. Our analysis also leads to a general principle to guide adaptations of Thompson sampling for pure-exploration problems. Numerical experiments highlight the exceptional efficiency of our proposed algorithms relative to existing ones.
|
[
"Computer Science Archive->cs.LG",
"Statistics Archive->stat.ML"
] | 2023-10-30T07:29:17Z |
1209.1871
|
Fluctuation Theorems on Nishimori Line
|
The distribution of the performed work for spin glasses with gauge symmetry is considered. With the aid of the gauge symmetry, which leads to the exact/rigorous results in spin glasses, we find a fascinating relation of the performed work as the fluctuation theorem. The integral form of the resultant relation reproduces the Jarzynski-type equation for spin glasses we have obtained. We show that similar relations can be established not only for the distribution of the performed work but also that of the free energy of spin glasses with gauge symmetry, which provides another interpretation of the phase transition in spin glasses.
|
[
"Physics Archive->cond-mat->cond-mat.dis-nn",
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | 2012-09-10T02:55:09Z |
gr-qc/0103007
|
On the dual interpretation of zero-curvature Friedmann-Robertson-Walker models
|
Two possible interpretations of FRW cosmologies (perfect fluid or dissipative fluid)are considered as consecutive phases of the system. Necessary conditions are found, for the transition from perfect fluid to dissipative regime to occur, bringing out the conspicuous role played by a particular state of the system (the ''critical point '').
|
[
"Physics Archive->astro-ph",
"Physics Archive->gr-qc"
] | 2001-03-02T17:46:29Z |
2303.11972
|
A Post Quantum Key Agreement Protocol Based on a Modified Matrix Power Function over a Rectangular Matrices Semiring
|
We present an improved post quantum version of Sakalauskas matrix power function key agreement protocol, using rectangular matrices instead of the original square ones. Sakalauskas matrix power function is an efficient and secure way to generate a shared secret key, and using rectangular matrices provides additional flexibility and security. This method reduces the computational burden by allowing smaller random integer matrices while maintaining equal security. Another advantage of using the rank deficient rectangular matrices over key agreement protocols is that it blocks linearization attacks.
|
[
"Computer Science Archive->cs.CR"
] | 2023-03-21T16:07:17Z |
1110.2883
|
Non-Abelian gauge potentials in graphene bilayers
|
We study the effect of spatial modulations in the interlayer hopping of graphene bilayers, such as those that arise upon shearing or twisting. We show that their single-particle physics, characterized by charge accumulation and recurrent formation of zero-energy bands as the pattern period L increases, is governed by a non-Abelian gauge potential arising in the low-energy electronic theory due to the coupling between layers. We show that such gauge-type couplings give rise to a potential that, for certain discrete values of L, spatially confines states at zero energy in particular regions of the Moir\'e patterns. We also draw the connection between the recurrence of the flat zero-energy bands and the non-Abelian character of the potential.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall"
] | 2011-10-13T10:09:12Z |
0806.0905
|
Channel Capacity Limits of Cognitive Radio in Asymmetric Fading Environments
|
Cognitive radio technology is an innovative radio design concept which aims to increase spectrum utilization by exploiting unused spectrum in dynamically changing environments. By extending previous results, we investigate the capacity gains achievable with this dynamic spectrum approach in asymmetric fading channels. More specifically, we allow the secondary-to-primary and secondary-to-secondary user channels to undergo Rayleigh or Rician fading, with arbitrary link power. In order to compute the capacity, we derive the distributions of ratios of Rayleigh and Rician variables. Compared to the symmetric fading scenario, our results indicate several interesting features of the capacity behaviour under both average and peak received power constraints. Finally, the impact of multiple primary users on the capacity under asymmetric fading has also been studied.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2008-06-05T07:51:07Z |
2109.12273
|
FedProc: Prototypical Contrastive Federated Learning on Non-IID data
|
Federated learning allows multiple clients to collaborate to train high-performance deep learning models while keeping the training data locally. However, when the local data of all clients are not independent and identically distributed (i.e., non-IID), it is challenging to implement this form of efficient collaborative learning. Although significant efforts have been dedicated to addressing this challenge, the effect on the image classification task is still not satisfactory. In this paper, we propose FedProc: prototypical contrastive federated learning, which is a simple and effective federated learning framework. The key idea is to utilize the prototypes as global knowledge to correct the local training of each client. We design a local network architecture and a global prototypical contrastive loss to regulate the training of local models, which makes local objectives consistent with the global optima. Eventually, the converged global model obtains a good performance on non-IID data. Experimental results show that, compared to state-of-the-art federated learning methods, FedProc improves the accuracy by $1.6\%\sim7.9\%$ with acceptable computation cost.
|
[
"Computer Science Archive->cs.DC",
"Computer Science Archive->cs.LG"
] | 2021-09-25T04:32:23Z |
1704.03148
|
Packing tree degree sequences
|
We consider packing tree degree sequences in this paper. We set up a conjecture that any arbitrary number of tree degree sequences without common leaves have edge disjoint tree realizations. This conjecture is known to be true for $2$ and $3$ tree degree sequences. In this paper, we give a proof for $4$ tree degree sequences and a computer aided proof for $5$ tree degree sequences. We also prove that for arbitrary $k$, $k$ tree degree sequences without common leaves and at least $2k-4$ vertices which are not leaves in any of the trees always have edge disjoint tree realizations. The main ingredient in all of the presented proofs is to find rainbow matchings in certain configurations.
|
[
"Mathematics Archive->math.CO"
] | 2017-04-11T05:33:50Z |
1106.5577
|
Gravitation as an Effect of Nonlinear Electrodynamics
|
We consider an approach to unification of the gravitational and electromagnetic interactions based on the existence of an effective Riemannian space in nonlinear electrodynamics. In the context of this approach, we discuss the possibility of screening the gravitational field.
|
[
"Physics Archive->gr-qc"
] | 2011-06-28T07:13:42Z |
2303.07260
|
Moment tensor inversion of perforation shots using distributed acoustic sensing
|
Distributed acoustic sensing (DAS) fibers have enabled various geophysical applications in unconventional reservoirs. Combined with perforation shots, a DAS fiber can record valuable guided waves that propagate in the reservoir formation and carry information about its properties. However, the representation of perforation shots as seismic sources, needed to conduct quantitative analysis, remains unknown. We model such sources using a superposition of three mechanisms for which we derive the moment tensor representation. Using field DAS data recorded in the same well where the perforations are located, we establish a workflow to invert the resolvable components of the total moment tensor for 100 different perforation shots. By scrutinizing the inversion results, we conjecture that the moment tensor can indicate how effectively a perforation shot creates micro-cracks in the surrounding rock. Furthermore, our inverted moment tensors form the basis for a subsequent elastic full-waveform inversion.
|
[
"Physics Archive->physics->physics.geo-ph"
] | 2023-03-13T16:37:34Z |
1803.04580
|
Mechanisms of pyroelectricity in three- and two-dimensional materials
|
Pyroelectricity is a very promising phenomenon in three- and two-dimensional (2D) materials, but first-principles calculations have not so far been used to elucidate the underlying mechanisms. Here we report density-functional theory (DFT) calculations based on the Born-Szigeti theory of pyroelectricity, by combining fundamental thermodynamics and the modern theory of polarization. We find satisfactory agreement with experimental data in the case of bulk benchmark materials, showing that the so-called electron-phonon renormalization, whose contribution has been viewed as negligible, is important. We predict out-of-plane pyroelectricity in the recently synthesized Janus MoSSe monolayer and in-plane pyroelectricity in the group-IV monochalcogenide GeS monolayer. It is notable that the so-called secondary pyroelectricity is found to be dominant in GeS monolayer. The present work opens a theoretical route to study the pyroelectric effect using DFT and provides a valuable tool in the search for new candidates for pyroelectric applications.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2018-03-13T00:02:25Z |
0810.1935
|
Expanding Ejecta in the Oxygen-Rich Supernova Remnant G292.0+1.8: Direct Measurement through Proper Motions
|
We report here the first study of proper motions of fast filaments in the young, oxygen-rich supernova remnant G292.0+1.8, carried out using a series of [O III] 5007 A emission-line images taken over a period of more than 21 years. Images taken at seven epochs from 1986 to 2008, all from telescopes at the Cerro Tololo Inter-American Observatory, show oxygen-emitting filaments, presumably ejecta fragments, throughout most of the remnant. We have measured the proper motions for 67 discrete filaments through two-dimensional correlations between images from different epochs. While the motions are small, mostly 20 to 100 milli-arcsec, they are nevertheless measurable through a robust technique of averaging measurements from many epoch pairs. The data are qualitatively consistent with a free-expansion model, and clearly show systematic motions outward from a point near the center of the radio/X-ray shell. Global fits using this model indicate an expansion center at R.A.(2000.0) = 11:24:34.4, Dec.(2000.0) = -59:15:51, and a kinematic age of 2990+-60 years. The young pulsar PSR J1124-5916 is located 46 arcsec southeast of the expansion center. Assuming that it was launched by the supernova, we expect the pulsar to be moving southeastward at 16 milli-arcsec, or a transverse velocity of 440 km/s. We find the fastest ejecta along an axis oriented roughly N-S in the plane of the sky, suggesting that a bipolar explosion produced G292.0+1.8, as appears to have been the case for Cas A.
|
[
"Physics Archive->astro-ph"
] | 2008-10-10T18:30:23Z |
2201.05471
|
Multimodal Anti-Reflective Coatings for Perfecting Anomalous Reflection from Arbitrary Periodic Structures
|
Metasurfaces possess vast wave-manipulation capabilities, including reflection and refraction of a plane wave into non-standard directions. This requires meticulously-designed sub-wavelength meta-atoms in each period of the metasurface which guarantee unitary coupling to the desired Floquet-Bloch mode or, equivalently, suppression of the coupling to other modes. Herein, we propose an entirely different scheme to achieve such suppression, alleviating the need to devise and realize such dense scrupulously-engineered polarizable particles. Extending the concept of anti-reflective coatings to enable simultaneous manipulation of multiple modes, we show theoretically and experimentally that a simple superstrate consisting of only several uniform dielectric layers can be modularly applied to \textit{aribtrary} periodic structures to yield perfect anomalous reflection. This multimodal anti-reflective coating (MARC), designed based on an analytical model, presents a conceptually and practically simpler paradigm for wave-control across a wide range of physical branches, from electromagnetics and acoustics to seismics and beyond.
|
[
"Physics Archive->physics->physics.app-ph",
"Physics Archive->physics->physics.optics"
] | 2022-01-13T13:51:55Z |
2108.03474
|
Solution Enumeration by Optimality in Answer Set Programming
|
Given a combinatorial search problem, it may be highly useful to enumerate its (all) solutions besides just finding one solution, or showing that none exists. The same can be stated about optimal solutions if an objective function is provided. This work goes beyond the bare enumeration of optimal solutions and addresses the computational task of solution enumeration by optimality (SEO). This task is studied in the context of Answer Set Programming (ASP) where (optimal) solutions of a problem are captured with the answer sets of a logic program encoding the problem. Existing answer-set solvers already support the enumeration of all (optimal) answer sets. However, in this work, we generalize the enumeration of optimal answer sets beyond strictly optimal ones, giving rise to the idea of answer set enumeration in the order of optimality (ASEO). This approach is applicable up to the best k answer sets or in an unlimited setting, which amounts to a process of sorting answer sets based on the objective function. As the main contribution of this work, we present the first general algorithms for the aforementioned tasks of answer set enumeration. Moreover, we illustrate the potential use cases of ASEO. First, we study how efficiently access to the next-best solutions can be achieved in a number of optimization problems that have been formalized and solved in ASP. Second, we show that ASEO provides us with an effective sampling technique for Bayesian networks.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.LO"
] | 2021-08-07T15:50:23Z |
hep-ex/0604048
|
Measurement of the DA$\Phi$NE luminosity with the KLOE detector using large angle Bhabha scattering
|
We describe the method of measuring the integrated luminosity of the $e^+e^-$ collider DA$\Phi$NE, the Frascati $\phi-$factory. The measurement is done with the KLOE detector selecting large angle Bhabha scattering events and normalizing them to the effective cross section. The $e^+e^- \to e^+e^-(\gamma)$ cross section is calculated using different event generators which account for the $O(\alpha)$ radiative initial and final state corrections, and the $\phi$ resonance contribution. The accuracy of the measurement is 0.6%, where 0.3% comes from systematic errors related to the event counting and 0.5% from theoretical evaluations of the cross section.
|
[
"Physics Archive->hep->hep-ex"
] | 2006-04-26T19:41:40Z |
1003.3416
|
A Diagrammatic Temperley-Lieb Categorification
|
The monoidal category of Soergel bimodules categorifies the Hecke algebra of a finite Weyl group. In the case of the symmetric group, morphisms in this category can be drawn as graphs in the plane. We define a quotient category, also given in terms of planar graphs, which categorifies the Temperley-Lieb algebra. Certain ideals appearing in this quotient are related both to the 1-skeleton of the Coxeter complex and to the topology of 2D cobordisms. We demonstrate how further subquotients of this category will categorify the cell modules of the Temperley-Lieb algebra.
|
[
"Mathematics Archive->math.RT"
] | 2010-03-17T17:32:06Z |
1303.0134
|
Bounds for the Second Hankel Determinant of Certain Univalent Functions
|
The estimates for the second Hankel determinant a_2a_4-a_3^2 of analytic function f(z)=z+a_2 z^2+a_3 z^3+...b for which either zf'(z)/f(z) or 1+zf"(z)/f'(z) is subordinate to certain analytic function are investigated. The estimates for the Hankel determinant for two other classes are also obtained. In particular, the estimates for the Hankel determinant of strongly starlike, parabolic starlike, lemniscate starlike functions are obtained.
|
[
"Mathematics Archive->math.CV"
] | 2013-03-01T10:25:26Z |
2101.02380
|
Who's a Good Boy? Reinforcing Canine Behavior in Real-Time using Machine Learning
|
In this paper we outline the development methodology for an automatic dog treat dispenser which combines machine learning and embedded hardware to identify and reward dog behaviors in real-time. Using machine learning techniques for training an image classification model we identify three behaviors of our canine companions: "sit", "stand", and "lie down" with up to 92% test accuracy and 39 frames per second. We evaluate a variety of neural network architectures, interpretability methods, model quantization and optimization techniques to develop a model specifically for an NVIDIA Jetson Nano. We detect the aforementioned behaviors in real-time and reinforce positive actions by making inference on the Jetson Nano and transmitting a signal to a servo motor to release rewards from a treat delivery apparatus.
|
[
"Computer Science Archive->cs.CV"
] | 2021-01-07T05:38:09Z |
1610.07822
|
The Conformal Hyperplet
|
We introduce a finite off-shell hypermultiplet with no off-shell central charge. This requires 192+192 degrees of freedom, all but 8+8 of which are auxiliary or gauge. In the absence of supergravity, the model has a saddle-point vacuum instability implying ghost-like propagators. These are cured by realizing the model superconformally, such that the erstwhile ghosts are realized as compensators. Gauge fixing these links the physical hypermultiplets to supergravity. This evokes the prospect of realizing ${\cal N}=4$ Super Yang-Mills theory off-shell.
|
[
"Physics Archive->hep->hep-th"
] | 2016-10-25T10:38:18Z |
cond-mat/0405191
|
A simple model for some unusual properties of martensitic transformation
|
We report a detailed numerical investigation of a recently introduced two dimensional model for square-to-rectangle martensitic transformation that explains several unusual features of the martensitic transformation. This model includes inertial effects, dissipation, long-range interaction between the transformed domains and an inhomogeneous stress field to describe the effect of lattice defects which serves as nucleation centers. Both single-site nucleation and multi-site nucleation has been studied for single quench situation and thermal cycling. The final stage morphologies of single-site nucleation and multi-site nucleation bear considerable similarity suggesting that the initial distribution of the defects is not important. Thermal cycling using continuous cooling and heating simulations show the existence of hysteresis in the transformation. More importantly, the rate of energy dissipated occurs in the forms of bursts with power law statistics for their amplitudes and durations which explains the results of acoustic emission signals observed in experiments. When the system is cycled repeatedly in a restricted domain of temperatures, the dissipated bursts of energy are repetitive, a feature observed in experiments. The associated morphology shows a complete reversal of the martensite domains thus throwing light on the mechanism underlying the shape memory effect. The model also exhibits tweed like patterns.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2004-05-10T15:19:46Z |
1904.02825
|
Recent results of the technological prototypes of the CALICE highly granular calorimeters
|
The CALICE Collaboration is conducting R\&D for highly granular calorimeters with an emphasis on detectors for Linear Colliders. This contribution briefly summarises recent tests of large scale technological prototypes of a silicon tungsten electromagnetic calorimeter and hadron calorimeters featuring either a gaseous medium or scintillator with a SiPM readout as active material.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->physics->physics.ins-det"
] | 2019-04-04T23:45:23Z |
astro-ph/0206105
|
Imaging the disk around the luminous young star LkHalpha 101 with infrared interferometry
|
The Herbig Ae/Be star LkHalpha 101 has been imaged at high angular resolution at a number of wavelengths in the near-infrared (from 1 to 3 microns) using the Keck 1 Telescope, and also observed in the mid-infrared (11.15 microns) using the U.C. Berkeley Infrared Spatial Interferometer (ISI). The resolved circular disk with a central hole or cavity reported in Tuthill et al. (2001) is confirmed. This is consistent with an almost face-on view (inclination < 35 deg) onto a luminous pre- or early-main sequence object surrounded by a massive circumstellar disk. With a multiple-epoch study spanning almost four years, relative motion of the binary companion has been detected, together with evidence for changes in the brightness distribution of the central disk/star. The resolution of the LkHalpha 101 disk by ISI mid-infrared interferometry constitutes the first such measurement of a young stellar object in this wavelength region. The angular size was found to increase only slowly from 1.6 to 11.15 microns, inconsistent with standard power-law temperature profiles usually encountered in the literature, supporting instead models with a hot inner cavity and relatively rapid transition to a cool or tenuous outer disk. The radius of the dust-free inner cavity is consistent with a model of sublimation of dust in equilibrium with the stellar radiation field. Measurements from interferometry have been combined with published photometry enabling an investigation of the energetics and fundamental properties of this prototypical system.
|
[
"Physics Archive->astro-ph"
] | 2002-06-07T03:00:57Z |
2005.03641
|
Major Change in Understanding of GRBs at TeV
|
Long-duration GRBs are the most luminous sources of electromagnetic radiation known in the Universe. Their initial prompt flashes of MeV gamma rays are followed by longer-lasting afterglow emission from radio waves to GeV gamma rays. Emission at TeV energies had been theoretically predicted, but never confirmed by observations. Here we report the detection of a huge signal from GRB 190114C in the TeV energy range by the MAGIC imaging atmospheric Cherenkov telescopes. Starting one minute after the onset of the burst, gamma rays in the energy range 0.2 -1 TeV were observed at more than 50 sigma level. This allowed us to study the spectral and temporal development of the GRB, revealing a new emission component in the afterglow with a power comparable to that of the synchrotron component. We found a second peak in the spectral energy distribution of the GRB at an energy of few hundred GeVs. Our modeling, based on the data from the two dozen space- and ground-based instruments that followed GRB 190114C at multiple wavelengths, supports the explanation that the second peak is due to the Inverse Compton radiation mechanism. The two-peaked structure of the spectral energy distribution allows us to constrain some of the key physical parameters of the GRB as the bulk Lorentz factor, minimal electron energy, the ratio of the radiation to magnetic field density. Recently also the H.E.S.S. imaging atmospheric Cherenkov telescope reported on a 5 sigma gamma-ray signal from the GRB 180720B, measured in the afterglow phase, 10 hours after the onset of the explosion. These observations prove that the GRBs are more powerful than assumed until recently. Because the observed GRBs did not show peculiar properties, we believe that from now on detection of gamma-ray signal from GRB afterglows at very high energies will become one of the standard observations.
|
[
"Physics Archive->astro-ph->astro-ph.HE"
] | 2020-05-07T17:45:45Z |
1410.3814
|
Iterates of Generic Polynomials and Generic Rational Functions
|
In 1985, Odoni showed that in characteristic $0$ the Galois group of the $n$-th iterate of the generic polynomial with degree $d$ is as large as possible. That is, he showed that this Galois group is the $n$-th wreath power of the symmetric group $S_d$. We generalize this result to positive characteristic, as well as to the generic rational function. These results can be applied to prove certain density results in number theory, two of which are presented here. This work was partially completed by the late R.W.K. Odoni in an unpublished paper.
|
[
"Mathematics Archive->math.NT"
] | 2014-10-14T19:49:33Z |
1212.0259
|
Mixed Interior Penalty Discontinuous Galerkin Methods for One-dimensional Fully Nonlinear Second Order Elliptic and Parabolic Equations
|
This paper is concerned with developing accurate and efficient numerical methods for one-dimensional fully nonlinear second order elliptic and parabolic partial differential equations (PDEs). In the paper we present a general framework for constructing high order interior penalty discontinuous Galerkin (IP-DG) methods for approximating viscosity solutions of these fully nonlinear PDEs. In order to capture discontinuities of the second order derivative $u_{xx}$ of the solution $u$, three independent functions $p_1, p_2$ and $p_3$ are introduced to represent numerical derivatives using various one-sided limits. The proposed DG framework, which is based on a nonstandard mixed formulation of the underlying PDE, embeds a nonlinear problem into a mostly linear system of equations where the nonlinearity has been modified to include multiple values of the second order derivative $u_{xx}$. The proposed framework extends a companion finite difference framework developed by the authors in [9] and allows for the approximation of fully nonlinear PDEs using high order polynomials and non-uniform meshes.In addition to the nonstandard mixed formulation setting, another main idea is to replace the fully nonlinear differential operator by a numerical operator, which is consistent with the differential operator and satisfies certain monotonicity (called g-monotonicity) properties. To ensure such a g-monotonicity, the crux of the construction is to introduce the numerical moment, which plays a critical role in the proposed DG framework. This paper also presents and analyzes numerical results for several numerical test problems which are used to guage the accuracy and efficiency of the proposed DG methods.
|
[
"Mathematics Archive->math.NA"
] | 2012-12-02T23:35:40Z |
2110.09536
|
On the environmental influence of groups and clusters of galaxies beyond the virial radius: Galactic conformity at few Mpc scales
|
The environment within dark matter haloes can quench the star formation of galaxies. However, environmental effects beyond the virial radius of haloes ($\gtrsim$ 1 Mpc) are less evident. An example is the debated correlation between colour or star formation in central galaxies and neighbour galaxies in adjacent haloes at large separations of several Mpc, referred to as two-halo galactic conformity. We use two galaxy catalogues generated from different versions of the semi-analytic model SAG applied to the MDPL2 cosmological simulation and the IllustrisTNG300 cosmological hydrodynamical simulation to study the two-halo conformity by measuring the quenched fraction of neighbouring galaxies as a function of the real-space distance from central galaxies. We find that low-mass central galaxies in the vicinity of massive systems ($M_{\rm 200c}$ $\geq$ 10$^{13}$ $h^{-1}~\rm M_{\odot}$) out to 5 $h^{-1}$ Mpc are preferentially quenched compared to other central galaxies at fixed stellar mass $M_{\star}$ or fixed host halo mass $M_{\rm 200c}$ at $z$ ~ 0. In all the galaxies catalogues is consistent that the low-mass ($M_{\star} < 10^{10}$ $h^{-1}~\rm M_{\odot}$ or $M_{\rm 200c} < 10^{11.8}$ $h^{-1}~\rm M_{\odot}$) central galaxies in the vicinity of clusters and, especially, groups of galaxies mostly produce the two-halo galactic conformity. On average, the quenched low-mass central galaxies are much closer to massive haloes than star-forming central galaxies of the same mass (by a factor of ~5). Our results agree with other works regarding the environmental influence of massive haloes that can extend beyond the virial radius and affect nearby low-mass central galaxies.
|
[
"Physics Archive->astro-ph->astro-ph.GA"
] | 2021-10-18T18:00:04Z |
1805.09145
|
RDF2Vec-based Classification of Ontology Alignment Changes
|
When ontologies cover overlapping topics, the overlap can be represented using ontology alignments. These alignments need to be continuously adapted to changing ontologies. Especially for large ontologies this is a costly task often consisting of manual work. Finding changes that do not lead to an adaption of the alignment can potentially make this process significantly easier. This work presents an approach to finding these changes based on RDF embeddings and common classification techniques. To examine the feasibility of this approach, an evaluation on a real-world dataset is presented. In this evaluation, the best classifiers reached a precision of 0.8.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.CL"
] | 2018-05-23T13:34:51Z |
2302.07387
|
PolyFormer: Referring Image Segmentation as Sequential Polygon Generation
|
In this work, instead of directly predicting the pixel-level segmentation masks, the problem of referring image segmentation is formulated as sequential polygon generation, and the predicted polygons can be later converted into segmentation masks. This is enabled by a new sequence-to-sequence framework, Polygon Transformer (PolyFormer), which takes a sequence of image patches and text query tokens as input, and outputs a sequence of polygon vertices autoregressively. For more accurate geometric localization, we propose a regression-based decoder, which predicts the precise floating-point coordinates directly, without any coordinate quantization error. In the experiments, PolyFormer outperforms the prior art by a clear margin, e.g., 5.40% and 4.52% absolute improvements on the challenging RefCOCO+ and RefCOCOg datasets. It also shows strong generalization ability when evaluated on the referring video segmentation task without fine-tuning, e.g., achieving competitive 61.5% J&F on the Ref-DAVIS17 dataset.
|
[
"Computer Science Archive->cs.CV"
] | 2023-02-14T23:00:25Z |
astro-ph/0209506
|
Properties of the Interstellar Medium and the Propagation of Cosmic Rays in the Galaxy
|
The problem of the origin of cosmic rays in the shocks produced by supernova explosions at energies below the so called 'knee' (at ~3*10$^6$ GeV) in the energy spectrum is addressed, with special attention to the propagation of the particles through the inhomogenious interstellar medium and the need to explain recent anisotropy results, [1]. It is shown that the fractal character of the matter density and magnetic field distribution leads to the likelihood of a substantial increase of spatial fluctuations in the cosmic ray energy spectra. While the spatial distribution of cosmic rays in the vicinity of their sources (eg. inside the Galactic disk) does not depend much on the character of propagation and is largely determined by the distribution of their sources, the distribution at large distances from the Galactic disk depends strongly on the character of the propagation. In particular, the fractal character of the ISM leads to what is known as 'anomalous diffusion' and such diffusion helps us to understand the formation of Cosmic Ray Halo. Anomalous diffusion allows an explanation of the recent important result from the Chacaltaya extensive air shower experiment [1], viz. a Galactic Plane Enhancement of cosmic ray intensity in the Outer Galaxy, which is otherwise absent for the case of the so-called 'normal' diffusion. All these effects are for just one reason: anomalous diffusion emphasizes the role of local phenomena in the formation of cosmic ray characteristics in our Galaxy and elsewhere.
|
[
"Physics Archive->astro-ph"
] | 2002-09-24T17:33:11Z |
1605.06729
|
Enterprise Software Service Emulation: Constructing Large-Scale Testbeds
|
Constructing testbeds for systems which are interconnected with large networks of other software services is a challenging task. It is particularly difficult to create testbeds facilitating evaluation of the non-functional qualities of a system, such as scalability, that can be expected in production deployments. Software service emulation is an approach for creating such testbeds where service behaviour is defined by emulate-able models executed in an emulation runtime environment. We present (i) a meta-modelling framework supporting emulate-able service modelling (including messages, protocol, behaviour and states), and (ii) Kaluta, an emulation environment able to concurrently execute large numbers (thousands) of service models, providing a testbed which mimics the behaviour and characteristics of large networks of interconnected software services. Experiments show that Kaluta can emulate 10,000 servers using a single physical machine, and is a practical testbed for scalability testing of a real, enterprise-grade identity management suite. The insights gained into the tested enterprise system were used to enhance its design.
|
[
"Computer Science Archive->cs.SE"
] | 2016-05-22T03:09:36Z |
0908.2808
|
A light scalar from walking solutions in gauge-string duality
|
We consider the type-IIB background generated by the strong-coupling limit of Nc D5 branes wrapped on S2, and focus our attention on a special class of solutions that exhibit walking behavior. We compute numerically the spectrum of scalar fluctuations around vacua of this class. Besides two cuts, and sequences of single poles converging on one of the branch points, the spectrum contains one isolated scalar, the mass of which is suppressed by the length of the walking region. Approximate scale-invariance symmetry in the walking region suggests that this be interpreted as a light dilaton, the pseudo-Goldstone boson of dilatations.
|
[
"Physics Archive->hep->hep-ph",
"Physics Archive->hep->hep-th"
] | 2009-08-20T11:02:50Z |
1106.1891
|
Beauty is Distractive: Particle production during multifield inflation
|
We consider a two-dimensional model of inflation, where the inflationary trajectory is "deformed" by a grazing encounter with an Extra Species/Symmetry Point (ESP) after the observable cosmological scales have left the Hubble radius. The encounter entails a sudden production of particles, whose backreaction causes a bending of the trajectory and a temporary decrease in speed, both of which are sensitive to initial conditions. This "modulated" effect leads to an additional contribution to the curvature perturbation, which can be dominant if the encounter is close. We compute associated non-Gaussianities, the bispectrum and its scale dependence as well as the trispectrum, which are potentially detectable in many cases. In addition, we consider a direct modulation of the coupling to the light field at the ESP via a modulaton field, a mixed scenario whereby the modulaton is identified with a second inflaton, and an extended Extra Species Locus (ESL); all of these scenarios lead to similar additional contributions to observables. We conclude that inflaton interactions throughout inflation are strongly constrained if primordial non-Gaussianities remain unobserved in current experiments such as PLANCK. If they are observed, an ESP encounter leaves additional signatures on smaller scales which may be used to identify the model.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | 2011-06-09T19:52:37Z |
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