cssi/SciSciGPT-SciSciNet huggingface dataset:
Testing Disk Instability Models for Giant Planet Formation

Disk instability is an attractive yet controversial means for the rapid formation of giant planets in our solar system and elsewhere. Recent concerns regarding the first adiabatic exponent of molecular hydrogen gas are addressed and shown not to lead to spurious clump formation in the author's disk instability models. A number of disk instability models have been calculated in order to further test the robustness of the mechanism, exploring the effects of changing the pressure equation of state, the vertical temperature profile, and other parameters affecting the temperature distribution. Possible reasons for differences in results obtained by other workers are discussed. Disk instability remains as a plausible formation mechanism for giant planets.
An Efficient Machine-Learning Approach for PDF Tabulation in Turbulent Combustion Closure

Probability density function (PDF) based turbulent combustion modeling is limited by the need to store multi-dimensional PDF tables that can take up large amounts of memory. A significant saving in...
Signed ordered knotlike quandle presentations

We define enhanced presentations of quandles via generators and relations with additional information comprising signed operations and an order structure on the set of generators. Such a presentation determines a virtual link diagram up to virtual moves. We list formal Reidemeister moves in which Tietze moves on the presented quandle are accompanied by corresponding changes to the order structure. Omitting the order structure corresponds to replacing virtual isotopy by welded isotopy. AMS Classification 57M25, 57M27; 27M05, 20F05
The Resilience of Kepler Systems to Stellar Obliquity

The Kepler mission and its successor K2 have brought forth a cascade of transiting planets. Many of these planetary systems exhibit multiple members, but a large fraction possess only a single transiting example. This overabundance of singles has led to the suggestion that up to half of Kepler systems might possess significant mutual inclinations between orbits, reducing the transiting number (the so-called "Kepler Dichotomy"). In a recent paper, Spalding & Batygin demonstrated that the quadrupole moment arising from a young, oblate star is capable of misaligning the constituent orbits of a close-in planetary system enough to reduce their transit number, provided that the stellar spin axis is sufficiently misaligned with respect to the planetary orbital plane. Moreover, tightly packed planetary systems were shown to be susceptible to becoming destabilized during this process. Here, we investigate the ubiquity of the stellar obliquity-driven instability within systems with a range of multiplicities. We find that most planetary systems analyzed, including those possessing only two planets, underwent instability for stellar spin periods below ~3 days and stellar tilts of order 30°. Moreover, we are able to place upper limits on the stellar obliquity in systems such as K2-38 (obliquity lesssim20°), where other methods of measuring the spin–orbit misalignment are not currently available. Given the known parameters of T-Tauri stars, we predict that up to one-half of super-Earth-mass systems may encounter the instability, in general agreement with the fraction typically proposed to explain the observed abundance of single-transiting systems.
Simple parking strategies

We investigate simple strategies that embody the decisions that one faces when trying to park near a popular destination. Should one park far from the target (destination), where finding a spot is easy, but then be faced with a long walk, or should one attempt to look for a desirable spot close to the target, where spots may be hard to find? We study an idealized parking process on a one-dimensional geometry where the desired target is located at $x=0$, cars enter the system from the right at a rate $\lambda$ and each car leaves at a unit rate. We analyze three parking strategies---meek, prudent, and optimistic---and determine which is optimal.
Minimal braid representatives of quasipositive links

We show that every quasipositive link has a quasipositive minimal braid representative, partially resolving a question posed by Orevkov. These quasipositive minimal braids are used to show that the maximal self-linking number of a quasipositive link is bounded below by the negative of the minimal braid index, with equality if and only if the link is an unlink. This implies that the only amphicheiral quasipositive links are the unlinks, answering a question of Rudolph's.
Learning-Based Image Reconstruction via Parallel Proximal Algorithm

In the past decade, sparsity-driven regularization has led to the advancement of image reconstruction algorithms. Traditionally, such regularizers rely on analytical models of sparsity [e.g., total variation (TV)]. However, more recent methods are increasingly centered around data-driven arguments inspired by deep learning. In this letter, we propose to generalize TV regularization by replacing the $\ell _1$ -penalty with an alternative prior that is trainable. Specifically, our method learns the prior via extending the recently proposed fast parallel proximal algorithm to incorporate data-adaptive proximal operators. The proposed framework does not require additional inner iterations for evaluating the proximal mappings of the corresponding learned prior. Moreover, our formalism ensures that the training and reconstruction processes share the same algorithmic structure, making the end-to-end implementation intuitive. As an example, we demonstrate our algorithm on the problem of deconvolution in a fluorescence microscope.
Novel 3d bosonic dualities from bosonization and holography

We use 3d bosonization dualities to derive new non-supersymmetric dualities between bosonic quiver theories in 2 + 1 dimensions. It is shown that such dualities are a natural non-Abelian generalization of the bosonic particle-vortex duality. A special case of such dualities is applicable to Chern-Simons theories living on interfaces in 3 + 1 dimensional SU(N) Yang-Mills theory across which the theta angle jumps. We also analyze such interfaces in a holographic construction which provides further evidence for novel dualities between quiver gauge theories and gauge theories with adjoint scalars. These conjectured dualities pass some stringent consistency tests.
DETECTION OF WIDESPREAD HOT AMMONIA IN THE GALACTIC CENTER

We present the detection of metastable inversion lines of ammonia (NH3) from energy levels high above the ground state. We detect these lines in both emission and absorption toward 15 of 17 positions in the central 300 pc of the Galaxy. In total, we observe seven metastable transitions of NH3: (8, 8), (9, 9), (10, 10), (11, 11), (12, 12), (13, 13) and (15, 15), with energies (in Kelvins) ranging from 680 to 2200 K. We also mapped emission from NH3 (8, 8) and (9, 9) in two clouds in the Sgr A complex (M-0.02–0.07 and M-0.13–0.08), and we find that the line emission is concentrated toward the dense centers of these molecular clouds. The rotational temperatures derived from the metastable lines toward M-0.02–0.07 and M-0.13–0.08 and an additional cloud (M0.25+0.01) range from 350 to 450 K. Similarly highly-excited lines of NH3 have previously been observed toward Sgr B2, where gas with kinetic temperatures of ~600 K had been inferred. Our observations show that the existence of a hot molecular gas component is not unique to Sgr B2, but rather appears common to many Galactic center molecular clouds. In M-0.02–0.07, we find that the hot NH3 contributes ~10% of the cloud's total NH3 column density, and further, that the hot NH3 in this cloud arises in gas which is extended or uniformly distributed on 10 arcsec scales. We discuss the implications of these constraints upon the nature of this hot gas component. In addition to the detection of hot metastable NH3 line emission, we also detect for the first time emission from nonmetastable inversion transitions of NH3 in both M-0.02–0.07 and M-0.13–0.08.
PSR B1849+00 probes the tiny-scale molecular gas ?

In this paper we present and discuss the great difference in OH absorption spectra against PSR B1849+00 and SNR G33.6+0.1 along the same line-of-sight. This finding is important as it clearly demonstrates that statistics of absorbing molecular gas depends on the size of the background source.
Instead of Rewriting Foreign Code for Machine Learning, Automatically Synthesize Fast Gradients

Applying differentiable programming techniques and machine learning algorithms to foreign programs requires developers to either rewrite their code in a machine learning framework, or otherwise provide derivatives of the foreign code. This paper presents Enzyme, a high-performance automatic differentiation (AD) compiler plugin for the LLVM compiler framework capable of synthesizing gradients of statically analyzable programs expressed in the LLVM intermediate representation (IR). Enzyme synthesizes gradients for programs written in any language whose compiler targets LLVM IR including C, C++, Fortran, Julia, Rust, Swift, MLIR, etc., thereby providing native AD capabilities in these languages. Unlike traditional source-to-source and operator-overloading tools, Enzyme performs AD on optimized IR. On a machine-learning focused benchmark suite including Microsoft's ADBench, AD on optimized IR achieves a geometric mean speedup of 4.5x over AD on IR before optimization allowing Enzyme to achieve state-of-the-art performance. Packaging Enzyme for PyTorch and TensorFlow provides convenient access to gradients of foreign code with state-of-the art performance, enabling foreign code to be directly incorporated into existing machine learning workflows.
Revealing spatially heterogeneous relaxation in a model nanocomposite

The detailed nature of spatially heterogeneous dynamics of glycerol-silica nanocomposites is unraveled by combining dielectric spectroscopy with atomistic simulation and statistical mechanical theory. Analysis of the spatial mobility gradient shows no "glassy" layer, but the α-relaxation time near the nanoparticle grows with cooling faster than the α-relaxation time in the bulk and is ∼20 times longer at low temperatures. The interfacial layer thickness increases from ∼1.8 nm at higher temperatures to ∼3.5 nm upon cooling to near bulk Tg. A real space microscopic description of the mobility gradient is constructed by synergistically combining high temperature atomistic simulation with theory. Our analysis suggests that the interfacial slowing down arises mainly due to an increase of the local cage scale barrier for activated hopping induced by enhanced packing and densification near the nanoparticle surface. The theory is employed to predict how local surface densification can be manipulated to control layer dynamics and shear rigidity over a wide temperature range.
Material Discovery and Design Principles for Stable, High Activity Perovskite Cathodes for Solid Oxide Fuel Cells

Critical to the development of improved solid oxide fuel cell (SOFC) technology are novel compounds with high oxygen reduction reaction (ORR) catalytic activity and robust stability under cathode operating conditions. Approximately 2145 distinct perovskite compositions are screened for potential use as high activity, stable SOFC cathodes, and it is verified that the screening methodology qualitatively reproduces the experimental activity, stability, and conduction properties of well-studied cathode materials. The calculated oxygen p-band center is used as a first principle-based descriptor of the surface exchange coefficient (k*), which in turn correlates with cathode ORR activity. Convex hull analysis is used under operating conditions in the presence of oxygen, hydrogen, and water vapor to determine thermodynamic stability. This search has yielded 52 potential cathode materials with good predicted stability in typical SOFC operating conditions and predicted k* on par with leading ORR perovskite catalysts. The established trends in predicted k* and stability are used to suggest methods of improving the performance of known promising compounds. The material design strategies and new materials discovered in the computational search help enable the development of high activity, stable compounds for use in future solid oxide fuel cells and related applications.
Efficient symmetry-preserving state preparation circuits for the variational quantum eigensolver algorithm

The variational quantum eigensolver is one of the most promising approaches for performing chemistry simulations using noisy intermediate-scale quantum (NISQ) processors. The efficiency of this algorithm depends crucially on the ability to prepare multi-qubit trial states on the quantum processor that either include, or at least closely approximate, the actual energy eigenstates of the problem being simulated while avoiding states that have little overlap with them. Symmetries play a central role in determining the best trial states. Here, we present efficient state preparation circuits that respect particle number, total spin, spin projection, and time-reversal symmetries. These circuits contain the minimal number of variational parameters needed to fully span the appropriate symmetry subspace dictated by the chemistry problem while avoiding all irrelevant sectors of Hilbert space. We show how to construct these circuits for arbitrary numbers of orbitals, electrons, and spin quantum numbers, and we provide explicit decompositions and gate counts in terms of standard gate sets in each case. We test our circuits in quantum simulations of the $${H}_{2}$$ and $$LiH$$ molecules and find that they outperform standard state preparation methods in terms of both accuracy and circuit depth.
Radiation hydrodynamical instabilities in cosmological and galactic ionization fronts

Ionization fronts, the sharp radiation fronts behind which H/He ionizing photons from massive stars and galaxies propagate through space, were ubiquitous in the universe from its earliest times. The cosmic dark ages ended with the formation of the first primeval stars and galaxies a few hundred Myr after the Big Bang. Numerical simulations suggest that stars in this era were very massive, 25–500 solar masses, with H(II) regions of up to 30,000 light-years in diameter. We present three-dimensional radiation hydrodynamical calculations that reveal that the I-fronts of the first stars and galaxies were prone to violent instabilities, enhancing the escape of UV photons into the early intergalactic medium (IGM) and forming clumpy media in which supernovae later exploded. The enrichment of such clumps with metals by the first supernovae may have led to the prompt formation of a second generation of low-mass stars, profoundly transforming the nature of the first protogalaxies. Cosmological radiation hydrodynamics is unique because ionizing photons coupled strongly to both gas flows and primordial chemistry at early epochs, introducing a hierarchy of disparate characteristic timescales whose relative magnitudes can vary greatly throughout a given calculation. We describe the adaptive multistep integration scheme we have developed for the self-consistent transport of both cosmological and galactic ionization fronts.
Reformulating Unsupervised Style Transfer as Paraphrase Generation.

Modern NLP defines the task of style transfer as modifying the style of a given sentence without appreciably changing its semantics, which implies that the outputs of style transfer systems should be paraphrases of their inputs. However, many existing systems purportedly designed for style transfer inherently warp the input's meaning through attribute transfer, which changes semantic properties such as sentiment. In this paper, we reformulate unsupervised style transfer as a paraphrase generation problem, and present a simple methodology based on fine-tuning pretrained language models on automatically generated paraphrase data. Despite its simplicity, our method significantly outperforms state-of-the-art style transfer systems on both human and automatic evaluations. We also survey 23 style transfer papers and discover that existing automatic metrics can be easily gamed and propose fixed variants. Finally, we pivot to a more real-world style transfer setting by collecting a large dataset of 15M sentences in 11 diverse styles, which we use for an in-depth analysis of our system.
THE STRUCTURE, DYNAMICS, AND STAR FORMATION RATE OF THE ORION NEBULA CLUSTER

The spatial morphology and dynamical status of a young, still-forming stellar cluster provide valuable clues to the conditions during the star formation event and the processes that regulated it. We analyze the Orion Nebula Cluster (ONC), utilizing the latest censuses of its stellar content and membership estimates over a large wavelength range. We determine the center of mass of the ONC and study the radial dependence of angular substructure. The core appears rounder and smoother than the outskirts, which is consistent with a higher degree of dynamical processing. At larger distances, the departure from circular symmetry is mostly driven by the elongation of the system, with very little additional substructure, indicating a somewhat evolved spatial morphology or an expanding halo. We determine the mass density profile of the cluster, which is well fitted by a power law that is slightly steeper than a singular isothermal sphere. Together with the interstellar medium density, which is estimated from average stellar extinction, the mass content of the ONC is insufficient by a factor ~1.8 to reproduce the observed velocity dispersion from virialized motions, in agreement with previous assessments that the ONC is moderately supervirial. This may indicate recent gas dispersal. Based on the latest estimates for the age spread in the system and our density profiles, we find that at the half-mass radius, 90% of the stellar population formed within ~5-8 free-fall times (t ff). This implies a star formation efficiency per t ff of ff ~ 0.04-0.07 (i.e., relatively slow and inefficient star formation rates during star cluster formation).
Kenneth G. Wilson: Renormalized After-Dinner Anecdotes

This is the transcript of the after-dinner talk I gave at the close of the 16 Nov 2013 symposium “Celebrating the Science of Kenneth Geddes Wilson” at Cornell University (see Fig. 1 for the poster). The video of my talk is on-line, and this transcript is more or less verbatim, with the slides used included as figures. I’ve also annotated it with a few clarifying footnotes, and provided references to the source materials where available.
The Rate of Core Collapse Supernovae to Redshift 2.5 From The CANDELS and CLASH Supernova Surveys

The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) and Cluster Lensing And Supernova survey with Hubble (CLASH) multi-cycle treasury programs with the Hubble Space Telescope (HST) have provided new opportunities to probe the rate of core-collapse supernovae (CCSNe) at high redshift, now extending to $z\approx2.5$. Here we use a sample of approximately 44 CCSNe to determine volumetric rates, $R_{CC}$, in six redshift bins in the range $0.1 95\%$ confidence) with SFRs from IR luminous galaxies, or with SFR models that include simple evolution in the initial mass function over time. This scaling factor is expected if the fraction of the IMF contributing to CCSN progenitors is in the 8 to 50 $M_{\odot}$ range. It is not supportive, however, of an upper mass limit for progenitors at $<20\,M_{\odot}$.
The structure of a quantized vortex in a Bose-Einstein Condensate

The structure of a quantized vortex in a Bose-Einstein Condensate is investigated using the projection method developed by Peierls, Yoccoz, and Thouless. This method was invented to describe the collective motion of a many-body system beyond the mean-field approximation. The quantum fluctuation has been properly built into the variational wave function, and a vortex is described by a linear combination of Feynman wave functions weighted by a Gaussian distribution in their center positions. In contrast to the solution of the Gross-Pitaevskii equation, the particle density is finite at the vortex axis and the vorticity is distributed in the core region.
The generalized recurrent set and strong chain recurrence

Fathi and Pageault have recently shown a connection between Auslander’s generalized recurrent set and Easton’s strong chain recurrent set. We study by examining that connection in more detail, as well as connections with other notions of recurrence. We give equivalent definitions that do not refer to a metric. In particular, we show that for any , and give a characterization of maps for which the generalized recurrent set is different from the ordinary chain recurrent set.
Conjugates, Filters and Quantum Mechanics

The Jordan structure of finite-dimensional quantum theory is derived, in a conspicuously easy way, from a few simple postulates concerning abstract probabilistic models (each defined by a set of basic measurements and a convex set of states). The key assumption is that each system A can be paired with an isomorphic $\textit{conjugate}$ system, $\overline{A}$, by means of a non-signaling bipartite state $\eta_A$ perfectly and uniformly correlating each basic measurement on A with its counterpart on $\overline{A}$. In the case of a quantum-mechanical system associated with a complex Hilbert space $\mathcal H$, the conjugate system is that associated with the conjugate Hilbert space $\overline{\mathcal H}$, and $\eta_A$ corresponds to the standard maximally entangled EPR state on ${\mathcal H} \otimes \overline{\mathcal H}$. A second ingredient is the notion of a $\textit{reversible filter}$, that is, a probabilistically reversible process that independently attenuates the sensitivity of detectors associated with a measurement. In addition to offering more flexibility than most existing reconstructions of finite-dimensional quantum theory, the approach taken here has the advantage of not relying on any form of the "no restriction" hypothesis. That is, it is not assumed that arbitrary effects are physically measurable, nor that arbitrary families of physically measurable effects summing to the unit effect, represent physically accessible observables. An appendix shows how a version of Hardy's "subspace axiom" can replace several assumptions native to this paper, although at the cost of disallowing superselection rules.
Finite noncommutative Chern-Simons with a Wilson line and the quantum Hall effect

We present a finite dimensional matrix model associated to the noncommutative Chern-Simons theory, obtained by inserting a Wilson line. For a specific choice of the representation of the Wilson line the model is equivalent to minimal modification of the matrix model which is compatible with finite dimensional matrices, and was introduced previously to study droplets of quantum Hall fluid. For other representations we obtain generalizations corresponding to regularized U(n) Chern-Simons theories, representing multilayered quantum Hall fluids.
Selective engineering of cavity resonance for frequency matching in optical parametric processes

We propose to selectively engineer a single cavity resonance to achieve frequency matching for optical parametric processes in high-Q microresonators. For this purpose, we demonstrate an approach, selective mode splitting (SMS), to precisely shift a targeted cavity resonance, while leaving other cavity modes intact. We apply SMS to achieve efficient parametric generation via four-wave mixing in high-Q silicon microresonators. The proposed approach is of great potential for broad applications in integrated nonlinear photonics.
Thermal Timescale Mass Transfer and the Evolution of White Dwarf Binaries

The evolution of binaries consisting of evolved main-sequence stars (1 < Md/M☉ < 3.5) with white dwarf companions (0.7 < Mwd/M☉ < 1.2) is investigated through the thermal mass-transfer phase. Taking into account the stabilizing effect of a strong, optically thick wind from the accreting white dwarf surface, we have explored the formation of several evolutionary groups of systems for progenitors with initial orbital periods of 1 and 2 days. The numerical results show that CO white dwarfs can accrete sufficient mass to evolve to a Type Ia supernova, and ONeMg white dwarfs can be built up to undergo accretion-induced collapse for donors more massive than about 2 M☉. For donors less massive than ~2 M☉, the system can evolve to form an He and CO or ONeMg white dwarf pair. In addition, sufficient helium can be accumulated (~0.1 M☉) in systems characterized by 1.6 Md/M☉ 1.9 and 0.8 Mwd/M☉ 1 such that sub-Chandrasekhar-mass models for Type Ia supernovae, involving off-center helium ignition, are possible for progenitor systems evolving via the Case A mass-transfer phase. For systems characterized by mass ratios 3, the system likely merges as a result of the occurrence of a delayed dynamical mass-transfer instability. We develop a semianalytical model to delineate these phases that can be easily incorporated in population synthesis studies of these systems.
Quantifying Community Characteristics of Maternal Mortality Using Social Media

While most mortality rates have decreased in the US, maternal mortality has increased and is among the highest of any OECD nation. Extensive public health research is ongoing to better understand the characteristics of communities with relatively high or low rates. In this work, we explore the role that social media language can play in providing insights into such community characteristics. Analyzing pregnancy-related tweets generated in US counties, we reveal a diverse set of latent topics including Morning Sickness, Celebrity Pregnancies, and Abortion Rights. We find that rates of mentioning these topics on Twitter predicts maternal mortality rates with higher accuracy than standard socioeconomic and risk variables such as income, race, and access to health-care, holding even after reducing the analysis to six topics chosen for their interpretability and connections to known risk factors. We then investigate psychological dimensions of community language, finding the use of less trustful, more stressed, and more negative affective language is significantly associated with higher mortality rates, while trust and negative affect also explain a significant portion of racial disparities in maternal mortality. We discuss the potential for these insights to inform actionable health interventions at the community-level.
Sample size determination for training cancer classifiers from microarray and RNA-seq data

The objective of many high-dimensional microarray and RNA-seq studies is to develop a classifier of cancer patients based on characteristics of their disease. The germinal center B-cell (GCB) classifier study in lymphoma and the National Cancer Institute’s Director’s Challenge lung (DC-lung) study are two examples. In recent years, such classifiers are often developed using regularized regression, such as the lasso. A critical question is whether a better classifier can be developed from a larger training set size and, if so, how large the training set should be. This paper examines these two questions using an existing sample size method and a novel sample size method developed here specifically for lasso logistic regression. Both methods are based on pilot data. We reexamine the lymphoma and lung cancer data sets to evaluate the sample sizes, and use resampling to assess the estimation methods. We also study application to an RNA-seq data set. We find that it is feasible to estimate sample size for regularized logistic regression if an adequate pilot data set exists. The GCB and the DC-lung data sets appear adequate, under specific assumptions. Existing human RNA-seq data sets are by and large inadequate, and cannot be used as pilot data. Pilot RNA-seq data can be simulated, and the methods in this paper can be used for sample size estimation. A MATLAB program is made available.
Period Identities of CM Forms on Quaternion Algebras

Waldspurger’s formula gives an identity between the norm of a torus period and an -function of the twist of an automorphic representation on GL(2). For any two Hecke characters of a fixed quadratic extension, one can consider the two torus periods coming from integrating one character against the automorphic induction of the other. Because the corresponding -functions agree, (the norms of) these periods—which occur on different quaternion algebras—are closely related. In this paper, we give a direct proof of an explicit identity between the torus periods themselves.
Kähler-Einstein metrics on Fano surfaces

Abstract We give an exposition of a result of G. Tian, which says that a Fano surface admits a Kahler–Einstein metric precisely when the Lie algebra of holomorphic vector fields is reductive.
CosmosDG: An hp-adaptive Discontinuous Galerkin Code for Hyper-resolved Relativistic MHD

We have extended Cosmos++, a multidimensional unstructured adaptive mesh code for solving the covariant Newtonian and general relativistic radiation magnetohydrodynamic (MHD) equations, to accommodate both discrete finite volume and arbitrarily high-order finite element structures. The new finite element implementation, called CosmosDG, is based on a discontinuous Galerkin (DG) formulation, using both entropy-based artificial viscosity and slope limiting procedures for the regularization of shocks. High-order multistage forward Euler and strong-stability preserving Runge–Kutta time integration options complement high-order spatial discretization. We have also added flexibility in the code infrastructure allowing for both adaptive mesh and adaptive basis order refinement to be performed separately or simultaneously in a local (cell-by-cell) manner. We discuss in this report the DG formulation and present tests demonstrating the robustness, accuracy, and convergence of our numerical methods applied to special and general relativistic MHD, although we note that an equivalent capability currently also exists in CosmosDG for Newtonian systems.
Improved bounds on information dissemination by Manhattan Random Waypoint model

With the popularity of portable wireless devices it is important to model and predict how information or contagions spread by natural human mobility - for understanding the spreading of deadly infectious diseases and for improving delay tolerant communication schemes. Formally, we model this problem by considering M moving agents, where each agent initially carries a distinct bit of information. When two agents are at the same location or in close proximity to one another, they share all their information with each other. We would like to know the time it takes until all bits of information reach all agents, called the flood time, and how it depends on the way agents move, the size and shape of the network and the number of agents moving in the network. We provide rigorous analysis for the Manhattan Random Way-point model (which takes paths with minimum number of turns), a convenient model used previously to analyze mobile agents, and find that with high probability the flood time is bounded by O (N log M[(N/M) log(NM)]), where M agents move on an N × N grid. In addition to extensive simulations, we use a data set of taxi trajectories to show that our method can successfully predict flood times in both experimental settings and the real world.
A basis of dimension-eight operators for anomalous neutral triple gauge boson interactions

Four independent dimension-eight operators give rise to anomalous neutral triple gauge boson interactions, one CP-even and three CP-odd. Only the CP-even operator interferes with the Standard Model for the production of a pair of on-shell neutral bosons. However, the effects are found to be tiny due mainly to the mismatch of the Z boson polarization between the productions from the SM and the new operator.
Spatial modeling of shot conversion in soccer to single out goalscoring ability

Goals are results of pin-point shots and it is a pivotal decision in soccer when, how and where to shoot. The main contribution of this study is two-fold. At first, after showing that there exists high spatial correlation in the data of shots across games, we introduce a spatial process in the error structure to model the probability of conversion from a shot depending on positional and situational covariates. The model is developed using a full Bayesian framework. Secondly, based on the proposed model, we define two new measures that can appropriately quantify the impact of an individual in soccer, by evaluating the positioning senses and shooting abilities of the players. As a practical application, the method is implemented on Major League Soccer data from 2016/17 season.
The six-point remainder function to all loop orders in the multi-Regge limit

We present an all-orders formula for the six-point amplitude of planar maximally supersymmetric $ \mathcal{N}=4 $ Yang-Mills theory in the leading-logarithmic approximation of multi-Regge kinematics. In the MHV helicity configuration, our results agree with an integral formula of Lipatov and Prygarin through at least 14 loops. A differential equation linking the MHV and NMHV helicity configurations has a natural action in the space of functions relevant to this problem — the single-valued harmonic polylogarithms introduced by Brown. These functions depend on a single complex variable and its conjugate, w and w * , which are quadratically related to the original kinematic variables. We investigate the all-orders formula in the near-collinear limit, which is approached as |w| → 0. Up to power-suppressed terms, the resulting expansion may be organized by powers of log |w|. The leading term of this expansion agrees with the all-orders double-leading-logarithmic approximation of Bartels, Lipatov, and Prygarin. The explicit form for the sub-leading powers of log |w| is given in terms of modified Bessel functions.
Segregation of polymers in confined spaces

We investigate the motion of two overlapping polymers confined in a 2D box. A statistical model is constructed using blob-free-energy arguments. We find spontaneous segregation under the condition L > R∥, and mixing under L < R∥, where L is the length of the box and R∥ is the polymer extension in an infinite slit. The segregation time (τ) is determined by solving a mean first-passage time problem and by performing Monte Carlo simulations. Both show a minimum in τ as a function of L. Although our results are restricted to 2D, the basic mechanism of competition between entropy and confinement leading to the minimum is suggestive of an evolutionary driving force for size selection.
$C^0$ approximations of foliations

Suppose that ℱ is a transversely oriented, codimension-one foliation of a connected, closed, oriented 3–manifold. Suppose also that ℱ has continuous tangent plane field and is taut; that is, closed smooth transversals to ℱ pass through every point of M. We show that if ℱ is not the product foliation S1 × S2, then ℱ can be C0 approximated by weakly symplectically fillable, universally tight contact structures. This extends work of Eliashberg and Thurston on approximations of taut, transversely oriented C2 foliations to the class of foliations that often arise in branched surface constructions of foliations. This allows applications of contact topology and Floer theory beyond the category of C2 foliated spaces.
Arithmetic properties for cubic partition pairs modulo powers of 3

Let b(n) denote the number of cubic partition pairs of n. In this paper, we aim to provide a strategy to obtain arithmetic properties of b(n). This gives affirmative answers to two of Lin’s conjectures.
RadVel: The Radial Velocity Modeling Toolkit

RadVel is an open-source Python package for modeling Keplerian orbits in radial velocity (RV) timeseries. RadVel provides a convenient framework to fit RVs using maximum a posteriori optimization and to compute robust confidence intervals by sampling the posterior probability density via Markov Chain Monte Carlo (MCMC). RadVel allows users to float or fix parameters, impose priors, and perform Bayesian model comparison. We have implemented real-time MCMC convergence tests to ensure adequate sampling of the posterior. RadVel can output a number of publication-quality plots and tables. Users may interface with RadVel through a convenient command-line interface or directly from Python. The code is object-oriented and thus naturally extensible. We encourage contributions from the community. Documentation is available at http://radvel.readthedocs.io.
White dwarfs in NGC 6791 : Avoiding the helium flash

We propose that the anomalously bright white dwarf luminosity function observed in NGC 6791 (Bedin et al.) is the consequence of the formation of 0.5 M☉ white dwarfs with helium cores instead of carbon cores. This may happen if mass loss during the ascent of the red giant branch is strong enough to prevent a star from reaching the helium flash. Such a model can explain the slower white dwarf cooling (relative to standard models) and fits naturally with scenarios advanced to explain extreme horizontal branch stars, a population of which are also found in this cluster.
The $L^2$–(co)homology of groups with hierarchies

We study group actions on manifolds that admit hierarchies, which generalizes the idea of Haken n-manifolds introduced by Foozwell and Rubinstein. We show that these manifolds satisfy the Singer conjecture in dimensions $n \le 4$. Our main application is to Coxeter groups whose Davis complexes are manifolds; we show that the natural action of these groups on the Davis complex has a hierarchy. Our second result is that the Singer conjecture is equivalent to the cocompact action dimension conjecture, which is a statement about all groups, not just fundamental groups of closed aspherical manifolds.
Tagged-Particle Statistics in Single-File Motion with Random-Acceleration and Langevin Dynamics

In the simplest model of single-file diffusion, N point particles wander on a segment of the x axis of length L, with hard core interactions, which prevent passing, and with overdamped Brownian dynamics $$\lambda \dot{x}=\eta (t)$$, where $$\eta (t)$$ has the form of Gaussian white noise with zero mean. In 1965 Harris showed that in the limit $$N\rightarrow \infty $$, $$L\rightarrow \infty $$ with constant $$\rho =N/L$$, the mean square displacement of a tagged particle grows subdiffusively, as $$t^{1/2}$$, for long times. Recently, it has been shown that the proportionality constants of the $$t^{1/2}$$ law for randomly-distributed initial positions of the particles and for equally-spaced initial positions are not the same, but have ratio $$\sqrt{2}$$. In this paper we consider point particles on the x axis, which collide elastically, and which move according to (i) random-acceleration dynamics $$\ddot{x}=\eta (t)$$ and (ii) Langevin dynamics $$\ddot{x}+\lambda \dot{x}=\eta (t)$$. The mean square displacement and mean-square velocity of a tagged particle are analyzed for both types of dynamics and for random and equally-spaced initial positions and Gaussian-distributed initial velocities. We also study tagged particle statistics, for both types of dynamics, in the spreading of a compact cluster of particles, with all of the particles initially at the origin.
Pseudo-Anosov homeomorphisms and the lower central series of a surface group

Let Γk be the lower central series of a surface group Γ of a compact surface S with one boundary component. A simple question to ponder is whether a mapping class of S can be determined to be pseudo-Anosov given only the data of its action on Γ∕Γk for some k. In this paper, to each mapping class f which acts trivially on Γ∕Γk+1, we associate an invariant Ψk(f)∈ End(H1(S,ℤ)) which is constructed from its action on Γ∕Γk+2 . We show that if the characteristic polynomial of Ψk(f) is irreducible over ℤ, then f must be pseudo-Anosov. Some explicit mapping classes are then shown to be pseudo-Anosov.
About David Ruelle, After His 80th Birthday

This is, with minor modifications, a text read at the 114th Statistical Mechanics meeting, in honor of D. Ruelle and Y. Sinai, at Rutgers, Dec. 13–15, 2015. It does not attempt to analyze, or not even just quote, all works of David Ruelle; I discuss, as usual in such occasions, a few among his works with which I have most familiarity and which were a source of inspiration for me.
Dynamical Fragmentation of the T Pyxidis Nova Shell During Recurrent Eruptions

Hubble Space Telescope images of the ejecta surrounding the nova T Pyxidis resolve the emission into more than 2000 bright knots. We simulate the dynamical evolution of the ejecta from T Pyxidis during its multiple eruptions over the last 150 years using the adaptive mesh refinement code Ramses. We demonstrate that the observed knots are the result of Richtmyer-Meshkov gas dynamical instabilities (the equivalent of Rayleigh-Taylor instabilities in an accelerated medium). These instabilities are caused by the overrunning of the ejecta from the classical nova of 1866 by fast-moving ejecta from the six subsequent recurrent nova outbursts. Magnetic fields may play a role in determining knot scale and preventing their conductive evaporation. The model correctly predicts the observed expansion and dimming of the T Pyx ejecta as well as the knotty morphology. The model also predicts that deeper, high-resolution imagery will show filamentary structure connecting the knots. We show reprocessed Hubble Space Telescope imagery that shows the first hints of such a structure.
Tunable Coupling to a Mechanical Oscillator Circuit Using a Coherent Feedback Network

An innovative wiring of two familiar superconducting circuits, a microwave LC resonator containing a small mass on a spring and a microwave amplifier that measures the motion of the mass, feeds the output of the amplifier directly back to the first circuit, creating a quantum-devices-based network that can be continuously and dynamically tuned to optimize control and measurement capabilities.
A Brief Overview of Black Hole-Neutron Star Mergers

Of the three main types of binaries detectable through ground-based gravitational wave observations, black hole-neutron star (BHNS) mergers remain the most elusive. While candidates BHNS exist in the triggers released during the third observing run of the Advanced LIGO/Virgo collaboration, no detection has been confirmed so far. As for binary neutron star systems, BHNS binaries allow us to explore a wide range of physical processes, including the neutron star equation of state, nucleosynthesis, stellar evolution, high-energy astrophysics, and the expansion of the Universe. Here, we review some of the main features of BHNS systems: the distinction between disrupting and non-disrupting binaries, the types of outflows that BHNS mergers can produce, and the information that can be extracted from the observation of their gravitational wave and electromagnetic signals. We also emphasize that for the most likely binary parameters, BHNS mergers seem less likely to power electromagnetic signals than binary neutron star systems. Finally, we discuss some of the issues that still limit our ability to model and interpret electromagnetic signals from BHNS binaries.
An exactly solvable model for nonlinear resonant scattering

This work analyses the effects of cubic nonlinearities on certain resonant scattering anomalies associated with the dissolution of an embedded eigenvalue of a linear scattering system. These sharp peak-dip anomalies in the frequency domain are often called Fano resonances. We study a simple model that incorporates the essential features of this kind of resonance. It features a linear scatterer attached to a transmission line with a point-mass defect and coupled to a nonlinear oscillator. We prove two power laws in the small coupling (????0) and small nonlinearity (????0) regime. The asymptotic relation ????C?4 characterizes the emergence of a small frequency interval of triple harmonic solutions near the resonant frequency of the oscillator. As the nonlinearity grows or the coupling diminishes, this interval widens and, at the relation ????C?2, merges with another evolving frequency interval of triple harmonic solutions that extends to infinity. Our model allows rigorous computation of stability in the small ? and ? limit. The regime of triple harmonic solutions exhibits bistability?those solutions with largest and smallest response of the oscillator are linearly stable and the solution with intermediate response is unstable.
High-temperature domain walls of QCD with imaginary chemical potentials

We study QCD with massless quarks on ℝ3 × S1 under symmetry-twisted boundary conditions with small compactification radius, i.e. at high temperatures. Under suitable boundary conditions, the theory acquires a part of the center symmetry and it is spontaneously broken at high temperatures. We show that these vacua at high temperatures can be regarded as different symmetry-protected topological orders, and the domain walls between them support nontrivial massless gauge theories as a consequence of anomaly-inflow mechanism. At sufficiently high temperatures, we can perform the semi-classical analysis to obtain the domain-wall theory, and 2d U(Nc − 1) gauge theories with massless fermions match the ’t Hooft anomaly. We perform these analysis for the high-temperature domain wall of $$ {\mathbb{Z}}_{N_{\mathrm{c}}} $$ -QCD and also of Roberge-Weiss phase transitions.
Two Variations on the Periscope Theorem

A (multidimensional) spherical periscope is a system of two ideal mirrors that reflect every ray of light emanating from some point back to this point. A spherical periscope defines a local diffeomorphism of the space of rays through this point, and we describe such diffeomorphisms. We also solve a similar problem for (multidimensional) reversed periscopes, the systems of two mirrors that reverse the direction of a parallel beam of light.
Axisymmetric squirmers in Stokes fluid with nonuniform viscosity

Numerical techniques are employed to study the locomotion of a spheroidal squirmer in a complex fluid with a nutrient-dependent viscosity. It is found that the nonuniform viscosity significantly affects the pressure field around the swimmer rather than the velocity field. Results obtained here will be helpful in interpreting experimental observation where a microswimmer significantly affects a fluid's local rheology.
The nature and nurture of star clusters

Star clusters have hierarchical patterns in space and time, suggesting formation processes in the densest regions of a turbulent interstellar medium. Clusters also have hierarchical substructure when they are young, which makes them all look like the inner mixed parts of a pervasive stellar hierarchy. Young field stars share this distribution, presumably because some of them came from dissolved clusters and others formed in a dispersed fashion in the same gas. The fraction of star formation that ends up in clusters is apparently not constant, but may increase with interstellar pressure. Hierarchical structure explains why stars form in clusters and why many of these clusters are self-bound. It also explains the cluster mass function. Halo globular clusters share many properties of disk clusters, including what appears to be an upper cluster cutoff mass. However, halo globulars are self-enriched and often connected with dwarf galaxy streams. The mass function of halo globulars could have initially been like the power-law mass function of disk clusters, but the halo globulars have lost their low-mass members. The reasons for this loss are not understood. It could have happened slowly over time as a result of cluster evaporation, or it could have happened early after cluster formation as a result of gas loss. The latter model explains best the observation that the globular cluster mass function has no radial gradient in galaxies.