ShantanuT01/DACTYL-Pretraining huggingface dataset:
We study factorization-breaking coefficients between the momentum dependent and momentum averaged flow vectors to probe flow fluctuations caused by initial-state fluctuations in heavy-ion collision. The coefficients for the flow vector squared and flow magnitude squared could be used for the extraction of flow angle decorrelations. We compare our model results with preliminary experimental data. We also present the predictions for the momentum dependent correlation between mixed flow harmonics.
With dynamic Monte Carlo simulations, we investigate the continuous phase transition in the three-dimensional three-state random-bond Potts model. We propose a useful technique to deal with the strong corrections to the dynamic scaling form. The critical point, static exponents $\beta$ and $\nu$, and dynamic exponent $z$ are accurately determined. Particularly, the results support that the exponent $\nu$ satisfies the lower bound $\nu \geqslant 2/d$.
By introducing the notion of relative derangements of type $B$, also called signed relative derangements, which are defined in terms of signed permutations, we obtain a type $B$ analogue of the well-known relation between relative derangements and the classical derangements. While this fact can be proved by using the principle of inclusion and exclusion, we present a combinatorial interpretation with the aid of the intermediate structure of signed skew derangements.
The systematics of energy staggering for the magnetic rotational bands with $M1$ and $E2$ transition properties strictly consistent with the features of good candidates of magnetic rotational bands in the $A\sim80$, 110, 130 and 190 mass regions are presented. The regularities exhibited by these bands concerning the staggering parameter which increases with increasing spin are in agreement with the semiclassical description of shears mechanism. In addition, the abnormal behaviours in the backbend regions or close to band termination have also been discussed. Taking the magnetic dipole bands with same configuration in three $N=58$ isotones, i.e., $^{103}$Rh, $^{105}$Ag, and~$^{107}$In, as examples, the transition from chiral rotation to magnetic rotation with the proton number approaching $Z=50$ is presented. Moreover, the self-consistent tilted axis cranking and principle axis cranking relativistic mean-field theories are applied to investigate the rotational mechanism in dipole band of $^{105}$Ag.
The experimental observation of the Dirac fermion states in $\beta_{12}$-borophene sheets and the discovery of their novel topological properties properties have made them a promising candidate for spintronic applications. Here, by combining non-equilibrium Green's function (NEGF) and tight-binding (TB) approximation, we study the charge and spin transport properties through a $\beta_{12}$-borophene nanoribbon (BNR) with the different edge shapes. We show when a BNR exposed to a nonlocal exchange magnetic field, the spin filtering occurs for both spin-up and spin-down so that the spin direction of transmitted electrons could be controlled by adjusting the energy of incoming electrons with the help of an external backgate voltage. It is found that an armchair BNR (ABNR) in the simultaneous presence of a transverse electric field and a nonlocal exchange field indicates a half-metallic nature which is electrically controllable. Moreover, the influence of local exchange field fields is evaluated by exposing the edges of ABNR to ferromagnetic strips with parallel and antiparallel configurations. Our findings show that the edge manipulations in ABNRs lead to the emergence of a giant magnetoresistance and a perfect spin filter. Finally, we studied the effects of edge vacancies and Anderson disorder on the spin-dependent conductance of an ABNR and find that the perfect spin polarization is not destroyed in the presence of Anderson disorder and various single vacancies. Our results reveal the outstanding spin transport properties of ABNRs for future spintronic devices.
A monomer-dimer model with a short-range attractive interaction favoring colinear dimers is considered on the lattice $\mathbb{Z}^2$. Although our choice of the chemical potentials results in more horizontal than vertical dimers, the horizontal dimers have no long-range traslational order - in agreement with the Heilmann-Lieb conjecture.
Wide-band-gap insulators such as NiO offer the exciting prospect of coherently manipulating electronic correlations with strong optical fields. Contrary to metals where rapid dephasing of optical excitation via electronic processes occurs, the sub-gap excitation in charge-transfer insulators has been shown to couple to low-energy bosonic excitations. However, it is currently unknown if the bosonic dressing field is composed of phonons or magnons. Here we use the prototypical charge-transfer insulator NiO to demonstrate that 1.5 eV sub-gap optical excitation leads to a renormalised NiO band-gap in combination with a significant reduction of the antiferromagnetic order. We employ element-specific X-ray reflectivity at the FLASH free-electron laser to demonstrate the reduction of the upper band-edge at the O 1s-2p core-valence resonance (K-edge) whereas the antiferromagnetic order is probed via X-ray magnetic linear dichroism (XMLD) at the Ni 2p-3d resonance (L2-edge). Comparing the transient XMLD spectral line shape to ground-state measurements allows us to extract a spin temperature rise of 65 +/- 5 K for time delays longer than 400 fs while at earlier times a non-equilibrium spin state is formed. We identify transient mid-gap states being formed during the first 200 fs accompanied by a band-gap reduction lasting at least up to the maximum measured time delay of 2.4 ps. Electronic structure calculations indicate that magnon excitations significantly contribute to the reduction of the NiO band gap.
Whenever gas is blown out of a galaxy, chances are that it contains some cosmic dust. This dust is an important part of the metals budget for the circumgalactic and intergalactic media, and traces the outflow and stripping history of the galaxy. The dust is also interesting in its own right, as dust plays an essential role in many astrophysical processes. We have only begun to learn about circumgalactic dust, and in particular we do not know how (and when) it escapes its host galaxy. Here we describe the prospects for measuring the dust mass and properties around many individual galaxies, which will form the basis for understanding how the dust got there.
Interaction with electron donor and acceptor molecules such as aniline and nitrobenzene brings about marked changes in the Raman spectrum and the electronic structure of graphene, prepared by the exfoliation of graphitic oxide.
Here we consider the product of varieties with $n$-blocks collections . We give some cohomological splitting conditions for rank 2 bundles. A cohomological characterization for vector bundles is also provided. The tools are Beilinson's type spectral sequences generalized by Costa and Mir\'o-Roig. Moreover we introduce a notion of Castelnuovo-Mumford regularity on a product of finitely many projective spaces and smooth quadric hypersurfaces in order to prove two splitting criteria for vector bundle with arbitrary rank.
We study the thermodynamics of the Hamiltonian Mean Field (HMF) model with an external potential playing the role of a "magnetic field". If we consider only fully stable states, this system does not present any phase transition. However, if we take into account metastable states (for a restricted class of perturbations), we find a very rich phenomenology. In particular, the system displays a region of negative specific heats in the microcanonical ensemble in which the temperature decreases as the energy increases. This leads to ensembles inequivalence and to zeroth order phase transitions similar to the "gravothermal catastrophe" and to the "isothermal collapse" of self-gravitating systems. In the present case, they correspond to the reorganization of the system from an "anti-aligned" phase (magnetization pointing in the direction opposite to the magnetic field) to an "aligned" phase (magnetization pointing in the same direction as the magnetic field). We also find that the magnetic susceptibility can be negative in the microcanonical ensemble so that the magnetization decreases as the magnetic field increases. The magnetic curves can take various shapes depending on the values of energy or temperature. We describe hysteretic cycles involving positive or negative susceptibilities. We also show that this model exhibits gaps in the magnetization at fixed energy, resulting in ergodicity breaking.
The PULSE@Parkes project has been designed to monitor the rotation of radio pulsars over time spans of days to years. The observations are obtained using the Parkes 64-m and 12-m radio telescopes by Australian and international high school students. These students learn the basis of radio astronomy and undertake small projects with their observations. The data are fully calibrated and obtained with the state-of-the-art pulsar hardware available at Parkes. The final data sets are archived and are currently being used to carry out studies of 1) pulsar glitches, 2) timing noise, 3) pulse profile stability over long time scales and 4) the extreme nulling phenomenon. The data are also included in other projects such as gamma-ray observatory support and for the Parkes Pulsar Timing Array project. In this paper we describe the current status of the project and present the first scientific results from the Parkes 12-m radio telescope. We emphasise that this project offers a straightforward means to enthuse high school students and the general public about radio astronomy while obtaining scientifically valuable data sets.
We report a systematic study on the low-temperature thermal conductivity (\kappa) of R_2Ti_2O_7 (R = Gd and Er) single crystals with different directions of magnetic field and heat current. It is found that the magnetic excitations mainly act as phonon scatterers rather than heat carriers, although these two materials have long-range magnetic orders at low temperatures. The low-T \kappa(H) isotherms of both compounds show rather complicated behaviors and have good correspondences with the magnetic transitions, where the \kappa(H) curves show drastic dip- or step-like changes. In comparison, the field dependencies of \kappa are more complicated in Gd_2Ti_2O_7, due to the complexity of its low-T phase diagram and field-induced magnetic transitions. These results demonstrate the significant coupling between spins and phonons in these materials and the ability of heat-transport properties probing the magnetic transitions.
Let $D=(V,A)$ be a digraph. A subset $S$ of $V$ is called a twin dominating set of $D$ if for every vertex $v\in V-S$, there exists vertices $u_1,u_2 \in S$ such that $(v,u_1)$ and $(u_2,v)$ are arcs in $D$. The minimum cardinality of a twin dominating set in $D$ is called the twin domination number of $D$ and is denoted by $\gamma ^{*}(D)$.   The upper orientable twin domination number of a graph $G$ is $DOM^{*}(G)=\max\{ \gamma ^{*}(D)|D \ \text{is an orientation of G} \}.$ It has been conjectured that for the complete graph $K_n$ with $n\geq 8$, $DOM^{*}(K_n)=\left\lceil \frac{n+1}{2}\right\rceil$. In this work we prove $DOM^{*}(K_8)= DOM^{*}(K_9)= 4$ and establish new upper bounds for $DOM^{*}(K_n)$, disproving the same above conjecture for all $n \geq 8$.
We calculate the quasifree photoproduction of pions and eta mesons on nuclei from 12C to 208Pb. Assuming that for the quasifree process the cross sections for pi/eta - photoproduction on a nucleon in medium are -- besides a lowering due to Pauli blocking -- identical to those on a free nucleon, we use these as an input. The produced mesons or resonances then propagate through the nucleus where they can undergo several scattering and absorption processes. This final state interaction, which leads to a lowering of the initial meson yield up to 70%, we simulate in a coupled channel Boltzmann-Uehling-Uhlenbeck transport model. It allows us to study in detail the influence of Fermi motion, Pauli blocking and of the additional decay channels for nucleon resonances in medium on the photoproduction cross section. The calculated total and differential cross sections are compared to experimental data and the influence of the different medium effects on the cross sections is discussed in detail.
Catheters are commonly inserted life supporting devices. X-ray images are used to assess the position of a catheter immediately after placement as serious complications can arise from malpositioned catheters. Previous computer vision approaches to detect catheters on X-ray images either relied on low-level cues that are not sufficiently robust or only capable of processing a limited number or type of catheters. With the resurgence of deep learning, supervised training approaches are begining to showing promising results. However, dense annotation maps are required, and the work of a human annotator is hard to scale. In this work, we proposed a simple way of synthesizing catheters on X-ray images and a scale recurrent network for catheter detection. By training on adult chest X-rays, the proposed network exhibits promising detection results on pediatric chest/abdomen X-rays in terms of both precision and recall.
Magnetically confined mountains on accreting neutron stars are promising sources of continuous-wave gravitational radiation and are currently the targets of directed searches with long-baseline detectors like the Laser Interferometer Gravitational Wave Observatory (LIGO). In this paper, previous ideal-magnetohydrodynamic models of isothermal mountains are generalized to a range of physically motivated, adiabatic equations of state. It is found that the mass ellipticity drops substantially, from \epsilon ~ 3e-4 (isothermal) to \epsilon ~ 9e-7 (non-relativistic degenerate neutrons), 6e-8 (relativistic degenerate electrons) and 1e-8 (non-relativistic degenerate electrons) (assuming a magnetic field of 3e12 G at birth). The characteristic mass M_{c} at which the magnetic dipole moment halves from its initial value is also modified, from M_{c}/M_{\sun} ~ 5e-4 (isothermal) to M_{c}/M_{\sun} ~ 2e-6, 1e-7, and 3e-8 for the above three equations of state, respectively. Similar results are obtained for a realistic, piecewise-polytropic nuclear equation of state. The adiabatic models are consistent with current LIGO upper limits, unlike the isothermal models. Updated estimates of gravitational-wave detectability are made. Monte Carlo simulations of the spin distribution of accreting millisecond pulsars including gravitational-wave stalling agree better with observations for certain adiabatic equations of state, implying that X-ray spin measurements can probe the equation of state when coupled with magnetic mountain models.
We report tunneling phenomena in double In$_{0.53}$Ga$_{0.47}$As quantum-well structures that are at odds with the conventional parallel-momentum-conserving picture of tunneling between two-dimensional systems. We found that the tunneling current was mostly determined by the correlation between the emitter and the state in one well, and not by that between those in both wells. Clear magnetic-field-dependent features were first observed before the main resonance, corresponding to tunneling channels into the Landau levels of the well near the emitter. These facts provide evidence of the violation of in-plane momentum conservation in two-dimensional systems.
Sodium pentazolates NaN5 andNa2N5, new high energy density materials, are discovered during first principles crystal structure search for the compounds of varying amounts of elemental sodium and nitrogen. The pentazole anion N5- is stabilized in the condensed phase by sodium Na+ cations at pressures exceeding 20 GPa, and becomes metastable upon release of pressure. The sodium azide (NaN3) precursor is predicted to undergo a chemical transformation above 50 GPa into sodium pentazolates NaN5 and Na2N5. The calculated Raman spectrum of NaN5 is in agreement with the experimental Raman spectrum of a previously unidentified substance appearing upon compression and heating of NaN3.
The chapter expounds a theory based on the interpretation of the dark energy as a strain energy of a physical continuum. The theory is based on the analogy that exists between the properties of space-time and the properties of elastic materials, when extended to four dimensions and the Lorentzian signature. In practice the starting point is an action integral that contains an additional term built as elastic potential energy of strained materials is. Besides this vacuum energy term matter/energy fields appear as usual. The strain energy term is based on the strain tensor of empty space-time which in turn is obtained from the non trivial part of the metric tensor. The Strained State Cosmology (SSC) is deduced from this approach when a Robertson-Walker symmetry is assumed: The result accounts for the accelerated expansion of the universe and agrees with observation passing four typical cosmological tests
We examine five dimensional extreme black holes with three charges in the matrix model. We build configurations of the 5+1 super Yang-Mills theory which correspond to black holes with transverse momentum charge. We calculate their mass and entropy from the super Yang-Mills theory and find that they match the semi-classical black hole results. We extend our results to nonextreme black holes in the dilute gas approximation.
Maximally supersymmetric Yang-Mills theories have several remarkable properties, among which are the cancellation of UV divergences, factorization of higher loop corrections and possible integrability. Much attention has been attracted to the N=4 D=4 SYM theory. The N=(1,1) D=6 SYM theory possesses similar properties but is nonrenomalizable and serves as a toy model for supergravity. We consider the on-shell four point scattering amplitude and analyze its perturbative expansion within the spin-helicity and superspace formalism. The integrands of the resulting diagrams coincide with those of the N=4 D=4 SYM and obey the dual conformal invariance. Contrary to 4 dimensions, no IR divergences on mass shell appear. We calculate analytically the leading logarithmic asymptotics in all loops. Their summation leads to a Regge trajectory which is calculated exactly. The leading powers of s are calculated up to six loops. Their summation is performed numerically and leads to a smooth function of s. The leading UV divergences are calculated up to 5 loops. The result suggests the geometrical progression which ends up in a finite expression. This leads us to a radical point of view on nonrenormalizable theories.
We present AdaFrame, a framework that adaptively selects relevant frames on a per-input basis for fast video recognition. AdaFrame contains a Long Short-Term Memory network augmented with a global memory that provides context information for searching which frames to use over time. Trained with policy gradient methods, AdaFrame generates a prediction, determines which frame to observe next, and computes the utility, i.e., expected future rewards, of seeing more frames at each time step. At testing time, AdaFrame exploits predicted utilities to achieve adaptive lookahead inference such that the overall computational costs are reduced without incurring a decrease in accuracy. Extensive experiments are conducted on two large-scale video benchmarks, FCVID and ActivityNet. AdaFrame matches the performance of using all frames with only 8.21 and 8.65 frames on FCVID and ActivityNet, respectively. We further qualitatively demonstrate learned frame usage can indicate the difficulty of making classification decisions; easier samples need fewer frames while harder ones require more, both at instance-level within the same class and at class-level among different categories.
We present exact results on the partition function of the $q$-state Potts model on various families of graphs $G$ in a generalized external magnetic field that favors or disfavors spin values in a subset $I_s = \{1,...,s\}$ of the total set of possible spin values, $Z(G,q,s,v,w)$, where $v$ and $w$ are temperature- and field-dependent Boltzmann variables. We remark on differences in thermodynamic behavior between our model with a generalized external magnetic field and the Potts model with a conventional magnetic field that favors or disfavors a single spin value. Exact results are also given for the interesting special case of the zero-temperature Potts antiferromagnet, corresponding to a set-weighted chromatic polynomial $Ph(G,q,s,w)$ that counts the number of colorings of the vertices of $G$ subject to the condition that colors of adjacent vertices are different, with a weighting $w$ that favors or disfavors colors in the interval $I_s$. We derive powerful new upper and lower bounds on $Z(G,q,s,v,w)$ for the ferromagnetic case in terms of zero-field Potts partition functions with certain transformed arguments. We also prove general inequalities for $Z(G,q,s,v,w)$ on different families of tree graphs. As part of our analysis, we elucidate how the field-dependent Potts partition function and weighted-set chromatic polynomial distinguish, respectively, between Tutte-equivalent and chromatically equivalent pairs of graphs.
Influence of shower fluctuations on the shape of lateral distribution of electrons in EAS of fixed size measured by scintillation counters is analyzed in framework of scaling formalism. Correction factors for the mean square radius of electrons are calculated for the experimental conditions of KASCADE array. Possible improvement of the primary mass discrimination by analysis of lateral distribution of EAS electrons is discussed in detail.
The distribution of a given sequence in the set of all sequences with n ones and m = M - n zeros are found by relating the problem to the partitions of a natural number in m natural summands, taking into account the order. The formulas obtained have many applications both in Physics and Mathematics. Examples discussed in the present paper are: non Markovian chains, partition functions of binary alloys and Ising magnets, generalized Kaplansky lemma, generalized Fibonacci numbers and a general expansion of \sum_{h=0}^{m} h^{r} {\binom{m}{h}}^{2} in terms of the Stirling numbers of second kind.
Variational principle for Kolmogorov-Petrovsky-Piskunov (KPP) minimal front speeds provides an efficient tool for statistical speed analysis, as well as a fast and accurate method for speed computation. A variational principle based analysis is carried out on the ensemble of KPP speeds through spatially stationary random shear flows inside infinite channel domains. In the regime of small root mean square (rms) shear amplitude, the enhancement of the ensemble averaged KPP front speeds is proved to obey the quadratic law under certain shear moment conditions. Similarly, in the large rms amplitude regime, the enhancement follows the linear law. In particular, both laws hold for the Ornstein-Uhlenbeck process in case of two dimensional channels. An asymptotic ensemble averaged speed formula is derived in the small rms regime and is explicit in case of the Ornstein-Uhlenbeck process of the shear. Variational principle based computation agrees with these analytical findings, and allows further study on the speed enhancement distributions as well as the dependence of enhancement on the shear covariance. Direct simulations in the small rms regime suggest quadratic speed enhancement law for non-KPP nonlinearities.
After an overview of general aspects of modelling the pulsation- convection interaction we present reasons why such simulations (in multidimensions) are needed but, at the same time, pose a considerable challenge. We then discuss, for several topics, what insights multidimensional simulations have either already provided or can be expected to yield in the future. We finally discuss properties of our ANTARES code. Many of these features can be expected to be characteristic of other codes which may possibly be applied to these physical questions in the foreseeable future.