cssi/SciSciGPT-SciSciNet huggingface dataset:
Unbalanced Sobolev Descent.

We introduce Unbalanced Sobolev Descent (USD), a particle descent algorithm for transporting a high dimensional source distribution to a target distribution that does not necessarily have the same mass. We define the Sobolev-Fisher discrepancy between distributions and show that it relates to advection-reaction transport equations and the Wasserstein-Fisher-Rao metric between distributions. USD transports particles along gradient flows of the witness function of the Sobolev-Fisher discrepancy (advection step) and reweighs the mass of particles with respect to this witness function (reaction step). The reaction step can be thought of as a birth-death process of the particles with rate of growth proportional to the witness function. When the Sobolev-Fisher witness function is estimated in a Reproducing Kernel Hilbert Space (RKHS), under mild assumptions we show that USD converges asymptotically (in the limit of infinite particles) to the target distribution in the Maximum Mean Discrepancy (MMD) sense. We then give two methods to estimate the Sobolev-Fisher witness with neural networks, resulting in two Neural USD algorithms. The first one implements the reaction step with mirror descent on the weights, while the second implements it through a birth-death process of particles. We show on synthetic examples that USD transports distributions with or without conservation of mass faster than previous particle descent algorithms, and finally demonstrate its use for molecular biology analyses where our method is naturally suited to match developmental stages of populations of differentiating cells based on their single-cell RNA sequencing profile. Code is available at this https URL .
DISCOVERY, PHOTOMETRY, AND KINEMATICS OF PLANETARY NEBULAE IN M 82*, **

Using an (O iii) �5007 on-band/off-band filter technique, we identify 109 planetary nebulae (PNe) candidates in the edge-on spiral galaxy M 82, using the FOCAS instrument at the 8.2m Subaru Telescope. The use of ancillary high-resolution Hubble Space Telescope ACS Himaging aided in confirming these candidates, helping to discriminate PNe from contaminants such as supernova rem- nants (SNRs) and compact Hii regions. Once identified, these PNe reveal a great deal about the host galaxy; our analysis covers kinematics, stellar distribution, and distance determination. Radial velocities were determined for 94 of these PNe using a method of slitless spectroscopy, from which we obtain a clear picture of the galaxy's rotation. Overall, our results agree with those derived by CO(2-1) and Hi measurements (Sofue 1998) that show a falling, near-Keplerian rotation curve. How- ever, we find a subset of our PNe that appear to lie far (� 1 kpc) above the plane, yet these objects appear to be rotating as fast as objects close to the plane. These objects will require further study to determine if they are members of a halo population, or if they can be interpreted as a manifestation of a thickened disk as a consequence of a past interaction with M 81. In addition, (O iii) �5007 emission line photometry of the PNe allows the construction of a planetary nebula luminosity function (PNLF) for the galaxy. Our distance determination for M 82, deduced from the observed PNLF, yields a larger distance than those derived using the tip of the red giant branch technique (TRGB; Dalcanton et al. 2009), using Cepheid variable stars in nearby group member M 81 (Freedman et al. 1994), or using the PNLF of M 81 (Jacoby et al. 1989). We show that this inconsistency most likely stems from our inability to completely correct for internal extinction imparted by this dusty, starburst galaxy. Additional observations that yield object-by-object foreground and internal extinction corrections are required to make an accurate distance measurement to this galaxy. Subject headings: galaxies: individual (M 82) — galaxies: kinematics and dynamics — planetary nebulae: general — techniques: radial velocities
Orientation Angles of a Pulsar’s Polarization Vector

A statistical model of the polarization of pulsar radio emission is used to derive the general statistics of a polarization vector's orientation angles. The theoretical distributions are compared with orientation angle histograms computed from single-pulse polarization observations of PSR B2020+28. The favorable agreement between the theoretical and measured distributions lends support to the underlying assumptions of the statistical model and demonstrates, like recent work on other pulsars, that the handedness of circular polarization is associated with the radiation's orthogonally polarized modes. Comprehensive directional statistics of the vector's orientation angles are also derived and are shown to follow the Watson bipolar and Fisher distributions in its limiting forms.
The motivic Mahowald invariant

The classical Mahowald invariant is a method for producing nonzero classes in the stable homotopy groups of spheres from classes in lower stems. We study the Mahowald invariant in the setting of motivic stable homotopy theory over $Spec(\mathbb{C})$. We compute a motivic version of the $C_2$-Tate construction for various motivic spectra, and show that this construction produces "blueshift" in these cases. We use these computations to show that the Mahowald invariant of $\eta^i$, $i \geq 1$, is the first element in Adams filtration $i$ of the $w_1$-periodic families constructed by Andrews ~\cite{And14}. This provides an exotic periodic analog of Mahowald and Ravenel's computation ~\cite{MR93} that the classical Mahowald invariant of $2^i$, $i \geq 1$, is the first element in Adams filtration $i$ of the $v_1$-periodic families constructed by Adams ~\cite{Ada66}.
LATTICE SUPERSYMMETRY WITH DOMAIN WALL FERMIONS

Supersymmetry, like Poincare symmetry, is softly broken at finite lattice spacing provided the gaugino mass term is strongly suppressed. Domain wall fermions provide the mechanism for suppressing this term by approximately imposing chiral symmetry. We present the first numerical simulations of supersymmetric SU(2) Yang-Mills on the lattice in d=4 dimensions using domain wall fermions.
On (2,3)-agreeable box societies

The notion of $(k,m)$-agreeable society was introduced by Deborah Berg et al.: a family of convex subsets of $\R^d$ is called $(k,m)$-agreeable if any subfamily of size $m$ contains at least one non-empty $k$-fold intersection. In that paper, the $(k,m)$-agreeability of a convex family was shown to imply the existence of a subfamily of size $\beta n$ with non-empty intersection, where $n$ is the size of the original family and $\beta\in[0,1]$ is an explicit constant depending only on $k,m$ and $d$. The quantity $\beta(k,m,d)$ is called the minimal \emph{agreement proportion} for a $(k,m)$-agreeable family in $\R^d$. If we only assume that the sets are convex, simple examples show that $\beta=0$ for $(k,m)$-agreeable families in $\R^d$ where $k<d$. In this paper, we introduce new techniques to find positive lower bounds when restricting our attention to families of $d$-boxes, i.e. cuboids with sides parallel to the coordinates hyperplanes. We derive explicit formulas for the first non-trivial case: the case of $(2,3)$-agreeable families of $d$-boxes with $d\geq 2$.
Bennequin Type Inequalities in Lens Spaces

We give criteria for an invariant of lens space links to bound the maximal self-linking number in certain tight contact lens spaces. As a corollary we extend the Franks-Williams-Morton inequality to the setting of lens spaces.
STUDY OF TWO SUCCESSIVE THREE-RIBBON SOLAR FLARES ON 2012 JULY 6

This Letter reports two rarely observed three-ribbon flares (M1.9 and C9.2) on 2012 July 6 in NOAA AR 11515, which we found using Hα observations of 01 resolution from the New Solar Telescope and Ca II H images from Hinode. The flaring site is characterized by an intriguing "fish-bone-like" morphology evidenced by both Hα images and a nonlinear force-free field (NLFFF) extrapolation, where two semi-parallel rows of low-lying, sheared loops connect an elongated, parasitic negative field with the sandwiching positive fields. The NLFFF model also shows that the two rows of loops are asymmetric in height and have opposite twists, and are enveloped by large-scale field lines including open fields. The two flares occurred in succession within half an hour and are located at the two ends of the flaring region. The three ribbons of each flare run parallel to the magnetic polarity inversion line, with the outer two lying in the positive field and the central one in the negative field. Both flares show surge-like flows in Hα apparently toward the remote region, while the C9.2 flare is also accompanied by EUV jets possibly along the open field lines. Interestingly, the 12-25 keV hard X-ray sources of the C9.2 flare first line up with the central ribbon then shift to concentrate on the top of the higher branch of loops. These results are discussed in favor of reconnection along the coronal null line, producing the three flare ribbons and the associated ejections.
Network flow routing under strategic link disruptions

This paper considers a 2-player strategic game for network routing under link disruptions. Player 1 (defender) routes flow through a network to maximize her value of effective flow while facing transportation costs. Player 2 (attacker) simultaneously disrupts one or more links to maximize her value of lost flow but also faces cost of disrupting links. This game is strategically equivalent to a zero-sum game. Linear programming duality and the max-flow min-cut theorem are applied to obtain properties that are satisfied in any mixed Nash equilibrium. In any equilibrium, both players achieve identical payoffs. While the defender's expected transportation cost decreases in attacker's marginal value of lost flow, the attacker's expected cost of attack increases in defender's marginal value of effective flow. Interestingly, the expected amount of effective flow decreases in both these parameters. These results can be viewed as a generalization of the classical max-flow with minimum transportation cost problem to adversarial environments.
When Cold Radial Migration is Hot: Constraints from Resonant Overlap

It is widely accepted that stars in a spiral disk, like the Milky Way's, can radially migrate on order a scale length over the disk's lifetime. With the exception of cold torquing, also known as "churning," processes that contribute to the radial migration of stars are necessarily associated with kinematic heating. Additionally, it is an open question whether or not an episode of cold torquing is kinemically cold over long radial distances. This study uses a suite of analytically based simulations to investigate the dynamical response when stars are subject to cold torquing and are also resonant with an ultraharmonic. Model results demonstrate that these populations are kinematically heated and have RMS changes in orbital angular momentum around corotation that can exceed those of populations that do not experience resonant overlap. Thus, kinematic heating can occur during episodes of cold torquing. In a case study of a Milky Way-like disk with an exponential surface density profile and flat rotation curve, up to 40% of cold torqued stars in the solar cylinder experience resonant overlap. This fraction increases toward the galactic center. To first approximation, the maximum radial excursions from cold torquing depend only on the strength of the spiral pattern and the underlying rotation curve. This work places an upper limit to these excursions to be the distance between the ultraharmonics, otherwise radial migration near corotation can kinematically heat. The diffusion rate for kinematically cold radial migration is thus constrained by limiting the step size in the random walk approximation.
Simultaneous Multiple Surface Segmentation Using Deep Learning

The task of automatically segmenting 3-D surfaces representing boundaries of objects is important for quantitative analysis of volumetric images, and plays a vital role in biomedical image analysis. Recently, graph-based methods with a global optimization property have been developed and optimized for various medical imaging applications. Despite their widespread use, these require human experts to design transformations, image features, surface smoothness priors, and re-design for a different tissue, organ or imaging modality. Here, we propose a Deep Learning based approach for segmentation of the surfaces in volumetric medical images, by learning the essential features and transformations from training data, without any human expert intervention. We employ a regional approach to learn the local surface profiles. The proposed approach was evaluated on simultaneous intraretinal layer segmentation of optical coherence tomography (OCT) images of normal retinas and retinas affected by age related macular degeneration (AMD). The proposed approach was validated on 40 retina OCT volumes including 20 normal and 20 AMD subjects. The experiments showed statistically significant improvement in accuracy for our approach compared to state-of-the-art graph based optimal surface segmentation with convex priors (G-OSC). A single Convolutional Neural Network (CNN) was used to learn the surfaces for both normal and diseased images. The mean unsigned surface positioning errors obtained by G-OSC method 2.31 voxels (\(95\%\) CI 2.02-2.60 voxels) was improved to 1.27 voxels (\(95\%\) CI 1.14-1.40 voxels) using our new approach. On average, our approach takes 94.34 s, requiring 95.35 MB memory, which is much faster than the 2837.46 s and 6.87 GB memory required by the G-OSC method on the same computer system.
Nonlinear quantum search using the Gross–Pitaevskii equation

We solve the unstructured search problem in constant time by computing with a physically motivated nonlinearity of the Gross–Pitaevskii type. This speedup comes, however, at the novel expense of increasing the time-measurement precision. Jointly optimizing these resource requirements results in an overall scaling of N1/4. This is a significant, but not unreasonable, improvement over the N1/2 scaling of Grover's algorithm. Since the Gross–Pitaevskii equation approximates the multi-particle (linear) Schrodinger equation, for which Grover's algorithm is optimal, our result leads to a quantum information-theoretic lower bound on the number of particles needed for this approximation to hold, asymptotically.
Cold Bose gases near Feshbach resonances

Abstract The lowest order constrained variational method [Phys. Rev. Lett. 88 (2002) 210403] has been generalized for a dilute (in the sense that the range of interatomic potential, R, is small compared with inter-particle spacing r0) uniform gas of bosons near the Feshbach resonance using the multi-channel zero-range potential model. The method has been applied to Na(F=1,mF=1) atoms near the B0=907 G Feshbach resonance. It is shown that at high densities na3⪢1, there are significant differences between our results for the real part of energy per particle and the one-channel zero-range potential approximation. We point out the possibility of stabilization of the uniform condensate for the case of negative scattering length.
Intensity Mapping in the Presence of Foregrounds and Correlated Continuum Emission

Intensity mapping has attracted significant interest as an approach to measuring the properties of the interstellar medium in typical galaxies at high redshift. Intensity mapping measures the statistics of surface brightness as a function of frequency, making it sensitive to not only all line emission of interest but also radiation from all other sources. Significant effort has gone into developing approaches that reject foreground contamination. Additionally, the target galaxies have multiple sources of emission that can complicate the interpretation of the line brightness.We describe the problem of jointly estimating correlated continuum emission and cleaning uncorrelated continuum emission, such as from the Milky Way. We apply these considerations to a cross-correlation of Planck data with BOSS quasars for a determination of [C II] for 2 < z < 3.2. Intensity mapping surveys with few bands have unique challenges for treating foregrounds and avoiding bias from correlated continuum emission. We show how a future intensity mapping survey with many bands can separate line from continuum emission in cross-correlation.
TRANSITING THE SUN: THE IMPACT OF STELLAR ACTIVITY ON X-RAY AND ULTRAVIOLET TRANSITS

Transits of hot Jupiters in X-rays and the ultraviolet have been shown to be both deeper and more variable than the corresponding optical transits. This variability has been attributed to hot Jupiters having extended atmospheres at these wavelengths. Using resolved images of the Sun from NASA’s Solar Dynamics Observatory spanning 3.5 yr of Solar Cycle 24 we simulate transit light curves of a hot Jupiter to investigate the impact of Solar-like activity on our ability to reliably recover properties of the planet’s atmosphere in soft X-rays (94 Å), the UV (131–1700 Å), and the optical (4500 Å). We find that for stars with activity levels similar to those of the Sun, the impact of stellar activity results in underestimating the derived radius of the planet in soft X-ray/EUV by up-to 25% or overestimating it by up to 50% depending on whether the planet occults active regions. We also find that in up to 70% of the X-ray light curves the planet transits over bright starspots. In the far-ultraviolet (1600 Å and 1700 Å), we find the mean recovered value of to be over-estimated by up to 20%. For optical transits we are able to consistently recover the correct planetary radius. We also address the implications of our results for transits of WASP-12 b and HD 189733b at short wavelengths.
K2 Discovery of Young Eclipsing Binaries in Upper Scorpius: Direct Mass and Radius Determinations for the Lowest Mass Stars and Initial Characterization of an Eclipsing Brown Dwarf Binary

We report the discovery of three low-mass double-lined eclipsing binaries in the pre-main sequence Upper Scorpius association, revealed by K2 photometric monitoring of the region over ~78 days. The orbital periods of all three systems are <5 days. We use the K2 photometry plus multiple Keck/HIRES radial velocities (RVs) and spectroscopic flux ratios to determine fundamental stellar parameters for both the primary and secondary components of each system, along with the orbital parameters. We present tentative evidence that EPIC 203868608 is a hierarchical triple system comprised of an eclipsing pair of ~25 MJup brown dwarfs with a wide M-type companion. If confirmed, it would constitute only the second double-lined eclipsing brown dwarf binary system discovered to date. The double-lined system EPIC 203710387 is composed of nearly identical M4.5-M5 stars with fundamentally determined masses and radii measured to better than 3% precision M_1 = 0.1183 ± 0.0028M_⊙, M_2 = 0.1076 ± 0.0031{M}_⊙ and R_1 = 0.417 ± 0.010R_⊙, R_2 = 0.450 ± 0.012R_⊙) from combination of the light curve and RV time series. These stars have the lowest masses of any stellar mass double-lined eclipsing binary to date. Comparing our derived stellar parameters with evolutionary models, we suggest an age of ~10–11 Myr for this system, in contrast to the canonical age of 3–5 Myr for the association. Finally, EPIC 203476597 is a compact single-lined system with a G8-K0 primary and a likely mid-K secondary whose lines are revealed in spectral ratios. Continued measurement of RVs and spectroscopic flux ratios will better constrain fundamental parameters and should elevate the objects to benchmark status. We also present revised parameters for the double-lined eclipsing binary UScoCTIO 5 (M_1 = 0.3336 ± 0.0022M_⊙, M_2 = 0.3200 ± 0.0022M_⊙ and R_1 = 0.862 ± 0.012, R_2 = 0.852 ± 0.013R_⊙), which are suggestive of a system age younger than previously reported. We discuss the implications of our results on these ~0.1–1.5 M_⊙ stars for pre-main-sequence evolutionary models.
Late-time Structure of the Bunch-Davies FRW Wavefunction

In this short note we organize a perturbation theory for the Bunch-Davies wavefunction in flat, accelerating cosmologies. The calculational technique avoids the in-in formalism and instead uses an analytic continuation from Euclidean signature. We will consider both massless and conformally coupled self-interacting scalars. These calculations explicitly illustrate two facts. The first is that IR divergences get sharper as the acceleration slows. The second is that UV-divergent contact terms in the Euclidean computation can contribute to the absolute value of the wavefunction in Lorentzian signature. Here UV divergent refers to terms involving inverse powers of the radial cutoff in the Euclidean computation. In Lorentzian signature such terms encode physical time dependence of the wavefunction.
THE MAGNETIC CLASSIFICATION OF SOLAR ACTIVE REGIONS 1992–2015

The purpose of this Letter is to address a blindspot in our knowledge of solar active region (AR) statistics. To the best of our knowledge, there are no published results showing the variation of the Mount Wilson magnetic classifications as a function of solar cycle based on modern observations. We show statistics for all ARs reported in the daily Solar Region Summary from 1992 January 1 to 2015 December 31. We find that the α and β class ARs (including all sub-groups, e.g., βγ, βδ) make up fractions of approximately 20% and 80% of the sample, respectively. This fraction is relatively constant during high levels of activity; however, an increase in the α fraction to about 35% and and a decrease in the β fraction to about 65% can be seen near each solar minimum and are statistically significant at the 2σ level. Over 30% of all ARs observed during the years of solar maxima were appended with the classifications γ and/or δ, while these classifications account for only a fraction of a percent during the years near the solar minima. This variation in the AR types indicates that the formation of complex ARs may be due to the pileup of frequent emergence of magnetic flux during solar maximum, rather than the emergence of complex, monolithic flux structures.
Topological nonrealization results via the Goodwillie tower approach to iterated loopspace homology

We prove a strengthened version of a theorem of Lionel Schwartz [17] that says that certain modules over the Steenrod algebra cannot be the mod 2 cohomology of a space. What is most interesting is our method, which replaces his iterated use of the Eilenberg–Moore spectral sequence by a single use of the spectral sequence converging to H .X IZ=2/ obtained from the Goodwillie tower for †X . Much of the paper develops basic properties of this spectral sequence.
On the origin of the X-rays and the nature of accretion in NGC 4261

We report on the X-ray properties of the radio galaxy NGC 4261, combining information from the XMM-Newton, Chandra ,a ndBeppoSAX satellites. Goals of this study are to investigate the origin of the X-rays from this low-power radio galaxy and the nature of the accretion process onto the central black hole. The X-ray spectrum of the nuclear source extending up to 100-150 keV is well described by a partially covered (covering factor>0.8) power law with a photon index ' 1:5 absorbed by a column density NH > 5 10 22 cm 2 . The X-ray luminosity associated with the non-thermal component is 5 10 41 erg s 1 . The nuclear source is embedded in a diuse hot gas (kT 0:6 0:65 keV), whose density profile implies a Bondi accretion rate of4:5 10 2 M yr 1 . For the first time rapid X-ray variability is detected in a low-power radio galaxy at more than 99% confidence level. The observed X-ray spectral and variability properties indicate the accretion flow as the most likely origin of the bulk X-ray continuum. This conclusion is strengthened by energetic considerations based on a comparison between the X-ray luminosity and the kinetic power of the jet, which also suggest that the Bondi accretion rate overestimates the actual accretion rate onto the black hole.
A database of number fields

We describe an online database of number fields which accompanies this paper. The database centers on complete lists of number fields with prescribed invariants. Our description here focuses on summarizing tables and connections to theoretical issues of current interest.
Euler's constant: Euler's work and modern developments

This paper has two parts. The first part surveys Euler’s work on the constant γ = 0.57721 · · · bearing his name, together with some of his related work on the gamma function, values of the zeta function, and divergent series. The second part describes various mathematical developments involving Euler’s constant, as well as another constant, the Euler–Gompertz constant. These developments include connections with arithmetic functions and the Riemann hypothesis, and with sieve methods, random permutations, and random matrix products. It also includes recent results on Diophantine approximation and transcendence related to Euler’s constant.
On combinatorial link Floer homology

Link Floer homology is an invariant for links defined using a suitable version of Lagrangian Floer homology. In an earlier paper, this invariant was given a combinatorial description with mod 2 coefficients. In the present paper, we give a self-contained presentation of the basic properties of link Floer homology, including an elementary proof of its invariance. We also fix signs for the differentials, so that the theory is defined with integer coefficients.
Manipulation of coupling and magnon transport in magnetic metal-insulator hybrid structures

Magnonic devices are important for implementing next-generation spintronics, but the adoption of such technology has long been stymied by the difficulty of integrating high-quality magnetic insulators with silicon. This study shows that highly effective magnonic spin valves can be realized at room temperature in Pt/YIG/permalloy hybrid structures grown on Si. In fact, a pronounced antiferromagnetic coupling between YIG and permalloy associated with growth on Si is the property that enables the spin valve's functionality. Since these are two critical materials for spin-wave devices, this form of interfacial coupling between them is of great importance to spintronics.
James Webb Space Telescope Optical Simulation Testbed I: overview and first results

The James Webb Space Telescope (JWST) Optical Simulation Testbed (JOST) is a tabletop workbench to study aspects of wavefront sensing and control for a segmented space telescope, including both commissioning and maintenance activities. JOST is complementary to existing optomechanical testbeds for JWST (e.g. the Ball Aerospace Testbed Telescope, TBT) given its compact scale and flexibility, ease of use, and colocation at the JWST Science & Operations Center. We have developed an optical design that reproduces the physics of JWST's three-mirror anastigmat using three aspheric lenses; it provides similar image quality as JWST (80% Strehl ratio) over a field equivalent to a NIRCam module, but at HeNe wavelength. A segmented deformable mirror stands in for the segmented primary mirror and allows control of the 18 segments in piston, tip, and tilt, while the secondary can be controlled in tip, tilt and x, y, z position. This will be sufficient to model many commissioning activities, to investigate field dependence and multiple field point sensing & control, to evaluate alternate sensing algorithms, and develop contingency plans. Testbed data will also be usable for cross-checking of the WFS&C Software Subsystem, and for staff training and development during JWST's five- to ten-year mission.
Stochastic optimal control using semidefinite programming for moment dynamics

This paper presents a method to approximately solve stochastic optimal control problems in which the cost function and the system dynamics are polynomial. For stochastic systems with polynomial dynamics, the moments of the state can be expressed as a, possibly infinite, system of deterministic linear ordinary differential equations. By casting the problem as a deterministic control problem in moment space, semidefinite programming is used to find a lower bound on the optimal solution. The constraints in the semidefinite program are imposed by the ordinary differential equations for moment dynamics and semidefiniteness of the outer product of moments. From the solution to the semidefinite program, an approximate optimal control strategy can be constructed using a least squares method. In the linear quadratic case, the method gives an exact solution to the optimal control problem. In more complex problems, an infinite number of moment differential equations would be required to compute the optimal control law. In this case, we give a procedure to increase the size of the semidefinite program, leading to increasingly accurate approximations to the true optimal control strategy.
Scones: towards conversational authoring of sketches

Iteratively refining and critiquing sketches are crucial steps to developing effective designs. We introduce Scones, a mixed-initiative, machine-learning-driven system that enables users to iteratively author sketches from text instructions. Scones is a novel deep-learning-based system that iteratively generates scenes of sketched objects composed with semantic specifications from natural language. Scones exceeds state-of-the-art performance on a text-based scene modification task, and introduces a mask-conditioned sketching model that can generate sketches with poses specified by high-level scene information. In an exploratory user evaluation of Scones, participants reported enjoying an iterative drawing task with Scones, and suggested additional features for further applications. We believe Scones is an early step towards automated, intelligent systems that support human-in-the-loop applications for communicating ideas through sketching in art and design.
Atomic motion from the mean square displacement in a monatomic liquid

V-T theory is constructed in the many-body Hamiltonian formulation, and is being developed as a novel approach to liquid dynamics theory. In this theory the liquid atomic motion consists of two contributions, normal mode vibrations in a single representative potential energy valley, and transits, which carry the system across boundaries between valleys. The mean square displacement time correlation function (the MSD) is a direct measure of the atomic motion, and our goal is to determine if the V-T formalism can produce a physically sensible account of this motion. We employ molecular dynamics (MD) data for a system representing liquid Na, and find the motion evolves in three successive time intervals: on the first 'vibrational' interval, the vibrational motion alone gives a highly accurate account of the MD data; on the second 'crossover' interval, the vibrational MSD saturates to a constant while the transit motion builds up from zero; on the third 'random walk' interval, the transit motion produces a purely diffusive random walk of the vibrational equilibrium positions. This motional evolution agrees with, and adds refinement to, the MSD atomic motion as described by current liquid dynamics theories.
QUANTIFYING THE CARBON ABUNDANCES IN THE SECONDARY STARS OF SS CYGNI, RU PEGASI, AND GK PERSEI

We use a modified version of MOOG to generate large grids of synthetic spectra in an attempt to derive quantitative abundances for three CVs (GK Per, RU Peg, and SS Cyg) by comparing the models to moderate resolution (R ∼ 25,000) K-band spectra obtained with NIRSPEC on Keck. For each of the three systems we find solar, or slightly sub-solar values for [Fe/H], but significant deficits of carbon: for SS Cyg we find [C/ Fe] = −0.50, for RU Peg [C/Fe] = −0.75, and for GK Per [C/Fe] = −1.00. We show that it is possible to use lower resolution (R ∼ 2000) spectra to quantify carbon deficits. We examine realistic veiling scenarios and find that emission from H I or CO cannot reproduce the observations. Cataclysmic variables (CVs) are a diverse group of shortperiod binaries in which a late-type, Roche-lobe filling secondary star transfers matter through an accretion disk onto a white dwarf primary. The standard paradigm for the formation of CVs postulates that they start out as wide binaries (on the order of 1 AU), of moderate orbital period (=1 year). As the more massive component, the white dwarf progenitor, evolves off of the main sequence, the secondary star suddenly finds itself orbiting within the red giant photosphere. During this “common envelope” (CE) phase, much of the angular momentum of the binary is believed to be shed due to interactions of the secondary star with the atmosphere of the red giant. During this process, the binary period gets shortened, and the red giant envelope gets ejected. Depending on the input parameters used in standard CE models, between 50% and 90% of all of these close binary stars merge (c.f., Politano & Weiler 2007). After emerging from the CE phase, an epoch of angular momentum loss via magnetic braking (Verbunt & Zwaan 1981), lasting ≈10 −7 year (Warner 1995, p. 443) ,i s then required that leads to the formation of a semi-detached binary, and the mass transfer phase that signals the birth of a CV. In this scenario, the vast majority of CV secondary stars should not show any signs of evolution, as there just has not been sufficient time for the low mass secondary stars (M2  1 Me) in these systems to have begun to evolve off of the main sequence. Thus, the composition of the secondary stars should be relatively normal unless they have accreted matter with an unusual composition during the CE phase, or perhaps during classical novae eruptions. In an infrared spectroscopic survey of CVs, Harrison et al. (2004, 2005) found that the CO features of the secondary stars in a number of CVs were much weaker than expected for their spectral types. For U Gem, the CO features were extremely weak, yet the water vapor feature was normal for a spectral type of M4V. This suggested a deficit of carbon. Hamilton et al. (2011) have tabulated the list of CVs with weaker than expected CO features, and show that, when such data exists, analysis of UV spectra also find evidence for carbon deficiencies. One issue with the infrared spectroscopy
Metrics Matter in Community Detection.

We critically evaluate normalized mutual information (NMI) as an evaluation metric for community detection. NMI exaggerates the leximin method’s performance on weak communities: Does leximin, in finding the trivial singletons clustering, truly outperform eight other community detection methods? Three NMI improvements from the literature are AMI, rrNMI, and cNMI. We show equivalences under relevant random models, and for evaluating community detection, we advise one-sided AMI under the \(\mathbb {M}_\mathbf{all }\) model (all partitions of \(n\) nodes). This work seeks (1) to drive a conversation on robust measurements (2) to advocate evaluations which do not give “free lunch”.
A unified enumeration of 1-dimension garden algebras and valise Adinkras

In the study of supersymmetry in one dimension, various works enumerate sets of generators of garden algebras $GR(d,N)$ (and equivalently, valise Adinkras) for special cases $N = d = 4$ and $N = d = 8$, using group-theoretic methods and computer computation. We complement this work by enumerating the objects for arbitrary $N$ and $d$ via a formula in a streamlined manner.
Data-Driven Model Reduction for Stochastic Burgers Equations.

We present a class of efficient parametric closure models for 1D stochastic Burgers equations. Casting it as statistical learning of the flow map, we derive the parametric form by representing the unresolved high wavenumber Fourier modes as functionals of the resolved variable’s trajectory. The reduced models are nonlinear autoregression (NAR) time series models, with coefficients estimated from data by least squares. The NAR models can accurately reproduce the energy spectrum, the invariant densities, and the autocorrelations. Taking advantage of the simplicity of the NAR models, we investigate maximal space-time reduction. Reduction in space dimension is unlimited, and NAR models with two Fourier modes can perform well. The NAR model’s stability limits time reduction, with a maximal time step smaller than that of the K-mode Galerkin system. We report a potential criterion for optimal space-time reduction: the NAR models achieve minimal relative error in the energy spectrum at the time step, where the K-mode Galerkin system’s mean Courant–Friedrichs–Lewy (CFL) number agrees with that of the full model.
Mining self-similarity: Label super-resolution with epitomic representations

We show that simple patch-based models, such as epitomes (Jojic et al., 2003), can have superior performance to the current state of the art in semantic segmentation and label super-resolution, which uses deep convolutional neural networks. We derive a new training algorithm for epitomes which allows, for the first time, learning from very large data sets and derive a label super-resolution algorithm as a statistical inference over epitomic representations. We illustrate our methods on land cover mapping and medical image analysis tasks.
Online Optimization With Predictions and Switching Costs: Fast Algorithms and the Fundamental Limit

This article considers online optimization with a finite prediction window of cost functions and additional switching costs on the decisions. We study the fundamental limits of dynamic regret of any online algorithm for both the with-prediction and the no-prediction cases. Besides, we propose two gradient-based online algorithms: receding horizon gradient descent (RHGD) and receding horizon accelerated gradient (RHAG); and provide their regret upper bounds. RHAG's regret upper bound is close to the lower bound, indicating the tightness of our lower bound and that our RHAG is near-optimal. Finally, we conduct numerical experiments to complement the theoretical results.
Japanese Public Opinion, Political Persuasion, and the Treaty on the Prohibition of Nuclear Weapons

The Treaty on the Prohibition of Nuclear Weapons (TPNW) poses a challenge to decades of Japanese nuclear policy. While Japan has relied on the US nuclear umbrella since the aftermath of World War I...
Randomness Concerns when Deploying Differential Privacy

The U.S. Census Bureau is using differential privacy (DP) to protect confidential respondent data collected for the 2020 Decennial Census of Population & Housing. The Census Bureau's DP system is implemented in the Disclosure Avoidance System (DAS) and requires a source of random numbers. We estimate that the 2020 Census will require roughly 90TB of random bytes to protect the person and household tables. Although there are critical differences between cryptography and DP, they have similar requirements for randomness. We review the history of random number generation on deterministic computersomitt, including von Neumann's "middle-square'' method, Mersenne Twister (MT19937) (the default NumPy random number generator, which we conclude is unacceptable for use in production privacy-preserving systems), and the Linux /dev/urandom device. We also review hardware random number generator schemes, including the use of so-called "Lava Lamps'' and the Intel Secure Key RDRAND instruction. We finally present our plan for generating random bits in the Amazon Web Services (AWS) environment using AES-CTR-DRBG seeded by mixing bits from/dev/urandom and the Intel Secure Key RDSEED instruction, a compromise of our desire to rely on a trusted hardware implementation, the unease of our external reviewers in trusting a hardware-only implementation, and the need to generate so many random bits.
Efficient Programs to Support Businesses During and After Lockdowns

I analyze efficient government interventions to mitigate financial distress during a severe macroeconomic downturn. At the macroeconomic level, the key variable is the gap between the real wage and the shadow cost of labor. This gap is large when unemployment is high. At the micro level, laissez-faire leads to excessive liquidation of businesses but an indiscriminate bailout prevents efficient reallocations and implies a large transfer from taxpayers to existing private creditors. I show that a cost-efficient intervention can be achieved with a continuation premium, whereby the government agrees to reduce its claims by the same haircut as private creditors plus a fixed premium. (JEL D24, G33, G38, H12)Received November 17, 2020; editorial decision November 23, 2020 by Editor Andrew Ellul.
On the Security of Homomorphic Encryption on Approximate Numbers

We present passive attacks against CKKS, the homomorphic encryption scheme for arithmetic on approximate numbers presented at Asiacrypt 2017. The attack is both theoretically efficient (running in expected polynomial time) and very practical, leading to complete key recovery with high probability and very modest running times. We implemented and tested the attack against major open source homomorphic encryption libraries, including HEAAN, SEAL, HElib and PALISADE, and when computing several functions that often arise in applications of the CKKS scheme to machine learning on encrypted data, like mean and variance computations, and approximation of logistic and exponential functions using their Maclaurin series.
A Model of Occupational Licensing and Statistical Discrimination

We develop a model of statistical discrimination in occupational licensing with endogenous occupation selection and wage determination. We find a unique equilibrium with sharp comparative statics. Our key theoretical result is that the licensing premium is higher for workers who are members of demographic groups that face a higher cost of licensing. The predictions of the model can explain, for example, the empirical finding in the literature that occupational licenses that preclude felons close the racial wage gap among men by conferring a higher premium to Black men than to White men (Blair and Chung 2018).
Localized optical vortex solitons in pair plasmas

The dynamics of short intense electromagnetic pulses propagating in a relativistic pair plasma with small temperature asymmetry is of current interest. Such pulses were shown to be governed by a nonlinear Schrodinger equation with a new type of focusing-defocusing nonlinearity. We provide an existence theory and numerical analysis for a special class of solutions, known as "ring-profiled" optical vortex solitons. Our methods include both a direct and constrained minimization. We give a necessary condition for the existence of nontrivial solutions and a series of interesting estimates in terms of the relevant parameters describing the electromagnetic pulse. Additionally, we use the constrained minimization approach and a finite element formalism to numerically study the behavior of the profiles of soliton solutions.
CenterFusion: Center-based Radar and Camera Fusion for 3D Object Detection

The perception system in autonomous vehicles is responsible for detecting and tracking the surrounding objects. This is usually done by taking advantage of several sensing modalities to increase robustness and accuracy, which makes sensor fusion a crucial part of the perception system. In this paper, we focus on the problem of radar and camera sensor fusion and propose a middle-fusion approach to exploit both radar and camera data for 3D object detection. Our approach, called CenterFusion, first uses a center point detection network to detect objects by identifying their center points on the image. It then solves the key data association problem using a novel frustum-based method to associate the radar detections to their corresponding object’s center point. The associated radar detections are used to generate radar-based feature maps to complement the image features, and regress to object properties such as depth, rotation and velocity. We evaluate CenterFusion on the challenging nuScenes dataset, where it improves the overall nuScenes Detection Score (NDS) of the state-of-the-art camera-based algorithm by more than 12%. We further show that CenterFusion significantly improves the velocity estimation accuracy without using any additional temporal information. The code is available at https://github.com/mrnabati/CenterFusion.
Error Bounds for Reduced Order Model Predictive Control

Model predictive control is a powerful framework for enabling optimal control of constrained systems. However, for systems that are described by high-dimensional state spaces this framework can be too computationally demanding for real-time control. Reduced order model predictive control (ROMPC) frameworks address this issue by leveraging model reduction techniques to compress the state space model used in the online optimal control problem. While this can enable real-time control by decreasing the online computational requirements, these model reductions introduce approximation errors that must be accounted for to guarantee constraint satisfaction and closed-loop stability for the controlled high-dimensional system. In this work we propose an offline methodology for efficiently computing error bounds arising from model reduction, and show how they can be used to guarantee constraint satisfaction in a previously proposed ROMPC framework. This work considers linear, discrete, time-invariant systems that are compressed by Petrov-Galerkin projections, and considers output-feedback settings where the system is also subject to bounded disturbances.
Bisphenol A promotes stress granule assembly and modulates the integrated stress response

Bisphenol-A (BPA) is a ubiquitous precursor of polycarbonate plastics that is found in the blood and serum of >92% of Americans. While BPA has been well documented to act as a weak estrogen receptor (ER) agonist, its effects on cellular stress are unclear. Here, we demonstrate that high-dose BPA causes stress granules (SGs) in human cells. A common estrogen derivative, β-estradiol, does not trigger SGs, indicating the mechanism of SG induction is not via the ER pathway. We also tested other structurally related environmental contaminants including the common BPA substitutes BPS and BPF, the industrial chemical 4-nonylphenol (4-NP) and structurally related compounds 4-EP and 4-VP, as well as the pesticide 2,4-dichlorophenoxyacetic acid (2,4-D). The variable results from these related compounds suggest that structural homology is not a reliable predictor of the capacity of a compound to cause SGs. Also, we demonstrate that BPA acts primarily through the PERK pathway to generate canonical SGs. Finally, we show that chronic exposure to a low physiologically relevant dose of BPA suppresses SG assembly upon subsequent acute stress. Interestingly, this SG inhibition does not affect phosphorylation of eIF2α or translation inhibition, thus uncoupling the physical assembly of SGs from translational control. Our work identifies additional effects of BPA beyond endocrine disruption that may have consequences for human health.
Exotic $\mathbb{Z}_N$ symmetries, duality, and fractons in 3+1-dimensional quantum field theory

Following our earlier analyses of nonstandard continuum quantum field theories, we study here gapped systems in 3+1 dimensions, which exhibit fractonic behavior. In particular, we present three dual field theory descriptions of the low-energy physics of the X-cube model. A key aspect of our constructions is the use of discontinuous fields in the continuum field theory. Spacetime is continuous, but the fields are not.