cssi/SciSciGPT-SciSciNet huggingface dataset:
GB-PANDAS: Throughput and heavy-traffic optimality analysis for affinity scheduling

Dynamic affinity scheduling has been an open problem for nearly three decades. The problem is to dynamically schedule multi-type tasks to multi-skilled servers such that the resulting queueing system is both stable in the capacity region (throughput optimality) and the mean delay of tasks is minimized at high loads near the boundary of the capacity region (heavy-traffic optimality). As for applications, dataintensive analytics like MapReduce, Hadoop, and Dryad fit into this setting, where the set of servers is heterogeneous for different task types, so the pair of task type and server determines the processing rate of the task. The load balancing algorithm used in such frameworks is an example of affinity scheduling which is desired to be both robust and delay optimal at high loads when hot-spots occur. Fluid model planning, the MaxWeight algorithm, and the generalized c?-rule are among the first algorithms proposed for affinity scheduling that have theoretical guarantees on being optimal in different senses, which will be discussed in the related work section. All these algorithms are not practical for use in data center applications because of their non-realistic assumptions. The join-the-shortest-queue-MaxWeight (JSQMaxWeight), JSQ-Priority, and weighted-workload algorithms are examples of load balancing policies for systems with two and three levels of data locality with a rack structure. In this work, we propose the Generalized-Balanced-Pandas algorithm (GB-PANDAS) for a system with multiple levels of data locality and prove its throughput optimality. We prove this result under an arbitrary distribution for service times, whereas most previous theoretical work assumes geometric distribution for service times. The extensive simulation results show that the GB-PANDAS algorithm alleviates the mean delay and has a better performance than the JSQMaxWeight algorithm by up to twofold at high loads. We believe that the GB-PANDAS algorithm is heavy-traffic optimal in a larger region than JSQ-MaxWeight, which is an interesting problem for future work.
The Effect of the Mass Accretion Rate on the Burst Oscillations in 4U 1728–34

We present a comprehensive study of the properties of nearly coherent brightness oscillations in a large sample of type I X-ray bursts observed from the low-mass X-ray binary 4U 1728-34. We have analyzed 547 ks of data of this source obtained with the Rossi X-Ray Timing Explorer over a 3 yr span from 1996 to 1999. The data contain 38 bursts, 16 of which show oscillations. We find no burst oscillations present when the inferred mass accretion rate of the system is lowest. Furthermore, we define a measure of the strength of the oscillations and find that this integrated strength increases with increasing mass accretion rate. This correlation is particularly evident within bursts detected only a few weeks apart and becomes less clear for bursts separated in time by several months to years. The correlation we find for 4U 1728-34 between the burst oscillations and the inferred accretion rate of the system is similar to that found for KS 1731-260 by Muno and coworkers, where the burst oscillations are only present at relatively high mass accretion rates. However, unlike the case for KS 1731-260, we find an anticorrelation in the bursts of 4U 1728-34 between the existence of episodes of photospheric radius expansion and the inferred mass accretion rate of the system. Moreover, we distinguish between burst oscillations present in the rise and in the decay phases of the burst and find that the bursts with oscillations only in the decay phase occur at intermediate accretion rates while those with oscillations in both the rise and the decay phases are concentrated at high inferred mass accretion rates. We discuss these results in the context of the theory of thermonuclear bursts and propose intrinsic differences in the neutron stars in KS 1731-260 and 4U 1728-34 as the origin of the different behaviors.
Electrically tunable harmonics in time-modulated metasurfaces for wavefront engineering

Modulation of metasurfaces in time gives rise to several exotic space-time scattering phenomena by violating the reciprocity and generation of higher-order frequency harmonics. We introduce a new design paradigm for time-modulated metasurfaces, offering electrically tunable engineering of the generated frequency harmonics and their emerging wavefronts by controlling the phase delay in modulation. It is demonstrated that the light acquires a dispersionless phase shift regardless of incident angle and polarization, upon undergoing frequency conversion in a time-modulated metasurface which is linearly proportional to the modulation phase delay and the order of generated frequency harmonic. The conversion efficiency to the frequency harmonics is independent of modulation phase delay and only depends on the modulation depth and resonant characteristics of the metasurface element, with the highest efficiency occurring in the vicinity of resonance, and decreasing away from the resonant regime. The design approach allows for creating tunable spatially varying phase discontinuties with 2{\pi} span in the wavefronts of generated frequency harmonics for a wide range of frequencies and incident angles. Specifically, we apply this approach to a time-modulated metasurface in the Teraherz regime consisted of graphene-wrapped silicon microwires. For this purpose, we use an accurate and efficient semi-analytical framework based on multipole scattering. We demonstrate the utility of the design for tunable beam steering and focusing of the generated frequency harmonics. Furthermore, we rigorously verify the broadband and wide-angle performance of the metasurface in manipulation of the generated frequency harmonics. The proposed design approach enables a new class of high-efficiency tunable metasurfaces with wide angular and frequency bandwidth, wavefront engineering capabilities and multi-functionality.
SegICP: Integrated deep semantic segmentation and pose estimation

Recent robotic manipulation competitions have highlighted that sophisticated robots still struggle to achieve fast and reliable perception of task-relevant objects in complex, realistic scenarios. To improve these systems' perceptive speed and robustness, we present SegICP, a novel integrated solution to object recognition and pose estimation. SegICP couples convolutional neural networks and multi-hypothesis point cloud registration to achieve both robust pixel-wise semantic segmentation as well as accurate and real-time 6-DOF pose estimation for relevant objects. Our architecture achieves 1 cm position error and < 5° angle error in real time without an initial seed. We evaluate and benchmark SegICP against an annotated dataset generated by motion capture.
Warm Decaying Dark Matter and the Hubble Tension

If a fraction of the dark matter is unstable and decays into dark radiation at around the time of matter-radiation equality, it could impact the expansion history of the universe in a way that helps to ameliorate the long-standing tension between the locally measured value of the Hubble constant and the value inferred from measurements of the cosmic microwave background and baryon acoustic oscillations (assuming standard ΛCDM cosmology). If this component of decaying dark matter is cold, however, it will modify the evolution of the gravitational potentials, leading to inconsistencies with these same data sets. With this in mind, we consider here a component of decaying warm dark matter, with a free-streaming length that is long enough to remain consistent with existing data. We study the background and perturbation evolution of warm decaying dark matter, and use cosmological data to constrain the mass, abundance and decay rate of such a particle. We find that a component of warm decaying dark matter can significantly reduce the tension between local and cosmological determinations of the Hubble constant.
A Catalog of Periodic Variables in Open Clusters M35 and NGC 2158

We present a catalog of 1,143 periodic variables, compiled from our image-subtracted photometric analysis of the K2 Campaign-0 super stamp. This super stamp is centered on the open clusters M35 and NGC 2158. Approximately 46% of our periodic variables were previously unreported. Of the catalog variables, we find that 331 are members of M35 and 56 are members of NGC 2158 (${P_{\mathrm{m}}~>~0.5}$). Our catalog contains two new transiting exoplanet candidates, both of which orbit field stars. The smaller planet candidate has a radius of $0.35~\pm~0.04 \ \rm R_{J}$ and orbits a K dwarf ($K_{\mathrm{p}}=15.4$ mag) with a transit depth of 2.9 millimag. The larger planet candidate has a radius of $0.72~\pm~0.02 \ \rm R_{J}$ and orbits a late G type star ($K_{\mathrm{p}}=15.7$ mag) with a transit depth of 2.2 millimag. The larger planet candidate maybe an unresolved binary or a false alarm. Our catalog includes 44 eclipsing binaries, including ten new detections. Of the eclipsing binaries, one is an M35 member and five are NGC 2158 members. Our catalog contains a total of 1,097 non-transiting variable stars, including a field $\delta$ Cepheid exhibiting double mode pulsations, 561 rotational variables, and 251 pulsating variables (primarily $\gamma$ Doradus and $\delta$ Scuti types). The periods of our catalog sources range between 43 minutes to 24 days. The known ages of our reported cluster variables will facilitate investigations of a variety of stellar evolutionary processes.
A Note on the Eigenvalue Density of Random Matrices

The distribution of eigenvalues of N×N random matrices in the limit N→∞ is the solution to a variational principle that determines the ground state energy of a confined fluid of classical unit charges. This fact is a consequence of a more general theorem, proven here, in the statistical mechanics of unstable interactions. Our result establishes the eigenvalue density of some ensembles of random matrices which were not covered by previous theorems.
Global classical solutions of the “one and one-half” dimensional Vlasov–Maxwell–Fokker–Planck system

We study the "one and one-half" dimensional Vlasov-Maxwell-Fokker-Planck system and obtain the first results concerning well-posedness of solutions. Specifically, we prove the global-in-time existence and uniqueness in the large of classical solutions to the Cauchy problem and a gain in regularity of the distribution function in its momentum argument.
Machine learning as ecology

Machine learning methods have had spectacular success on numerous problems. Here we show that a prominent class of learning algorithms - including Support Vector Machines (SVMs) - have a natural interpretation in terms of ecological dynamics. We use these ideas to design new online SVM algorithms that exploit ecological invasions, and benchmark performance using the MNIST dataset. Our work provides a new ecological lens through which we can view statistical learning and opens the possibility of designing ecosystems for machine learning.
TESTING DARK MATTER HALO MODELS OF QUASARS WITH THERMAL SUNYAEV–ZELDOVICH EFFECT

A statistical analysis of stacked Compton-y maps of quasar hosts with a median redshift of 1.5 using Millennium Simulation is performed to address two issues: one on the feedback energy from quasars and the other on testing dark matter halo models for quasar hosts. On the first, we find that at the resolution of FWHM = 10 arcmin obtained by Planck data, the observed thermal Sunyaev–Zeldovich (tSZ) effect can be entirely accounted for and explained by the thermal energy of halos sourced by the gravitational collapse of halos, without a need to invoke additional, large energy sources, such as quasar or stellar feedback. Allowing for uncertainties of dust temperature in the calibration of observed Compton-y maps, the maximum additional feedback energy is $\sim 25\%$ of that previously suggested. Second, we show that with an FWHM = 1 arcmin beam, tSZ measurements will provide a potentially powerful test of quasar-hosting dark matter halo models, limited only by possible observational systematic uncertainties, not by statistical ones, even in the presence of possible quasar feedback.
Time-bin and polarization superdense teleportation for space applications

To build a global quantum-communication network, low-transmission, fiber-based communication channels can be supplemented by using a free-space channel between a satellite and a ground station on Earth. We construct a system that generates hyperentangled photonic ``ququarts'' and measures them to execute multiple quantum-communication protocols of interest. We successfully execute and characterize superdense teleportation, a modified remote-state preparation protocol that transfers more quantum information than standard teleportation, for the same classical information cost, and moreover, is in principle deterministic. Our measurements show an average fidelity of $0.94\ifmmode\pm\else\textpm\fi{}0.02$, with a phase resolution of approximately ${7}^{\ensuremath{\circ}}$, allowing reliable transmission of $g{10}^{5}$ distinguishable quantum states. Additionally, we demonstrate the ability to compensate for the Doppler shift, which would otherwise prevent sending time-bin encoded states from a rapidly moving satellite, thus allowing the low-error execution of phase-sensitive protocols during an orbital pass. Finally, we show that the estimated number of received coincidence counts in a realistic implementation is sufficient to enable faithful reconstruction of the received state in a single pass.
Emission Mechanisms in X-Ray-faint Galaxies

Hot gas dominates the emission in X-ray-luminous early-type galaxies, but in relatively X-ray-faint systems, integrated X-ray emission from discrete stellar-like sources is thought to be considerable, although the amount of the contribution is controversial. To help resolve this issue, we examine the radial X-ray surface brightness distribution of 17 X-ray-faint galaxies observed with the ROSAT HRI and PSPC. We assume that the stellar contribution follows a de Vaucouleurs law while the hot gas component follows a King β model. For some galaxies, both models fit equally well, but for a number of systems, a dual component model yields the best fit, from which upper bounds are placed on the stellar contribution. Best-fit values for the stellar contribution are inconsistent with (lower than) that suggested by Fabbiano, Gioia, & Trinchieri and estimated from the bulge of M31 but are consistent with the Forman, Jones, & Tucker estimate of the stellar fraction in X-ray-faint elliptical and S0 galaxies. Our results indicate an upper limit to discrete sources of LX/LB = 1.6 × 1029 ergs s-1 L.
Projecting Flood-Inducing Precipitation with a Bayesian Analogue Model

The hazard of pluvial flooding is largely influenced by the spatial and temporal dependence characteristics of precipitation. When extreme precipitation possesses strong spatial dependence, the risk of flooding is amplified due to catchment factors such as topography that cause runoff accumulation. Temporal dependence can also increase flood risk as storm water drainage systems operating at capacity can be overwhelmed by heavy precipitation occurring over multiple days. While transformed Gaussian processes are common choices for modeling precipitation, their weak tail dependence may lead to underestimation of flood risk. Extreme value models such as the generalized Pareto processes for threshold exceedances and max-stable models are attractive alternatives, but are difficult to fit when the number of observation sites is large, and are of little use for modeling the bulk of the distribution, which may also be of interest to water management planners. While the atmospheric dynamics governing precipitation are complex and difficult to fully incorporate into a parsimonious statistical model, non-mechanistic analogue methods that approximate those dynamics have proven to be promising approaches to capturing the temporal dependence of precipitation. In this paper, we present a Bayesian analogue method that leverages large, synoptic-scale atmospheric patterns to make precipitation forecasts. Changing spatial dependence across varying intensities is modeled as a mixture of spatial Student-t processes that can accommodate both strong and weak tail dependence. The proposed model demonstrates improved performance at capturing the distribution of extreme precipitation over Community Atmosphere Model (CAM) 5.2 forecasts. Supplementary materials accompanying this paper appear online.
Switching Mechanism and the Scalability of Vertical-TFETs

In this brief, vertical tunnel field-effect transistors (v-TFETs) based on vertically stacked heretojunctions from 2-D transition metal dichalcogenide materials are studied by atomistic quantum transport simulations. The switching mechanism of a v-TFET is found to be different from previous predictions. As a consequence of this switching mechanism, the extension region where the materials are not stacked over is found to be critical for turning off the v-TFET. This extension region makes the scaling of v-TFETs challenging. In addition, due to the presence of both positive and negative charges inside the channel, v-TFETs also exhibit negative top gate capacitance. As a result, v-TFETs have good energy-delay products and are one of the promising candidates for low-power applications.
Inflation in Flatland

We investigate the symmetry structure of inflation in 2+1 dimensions. In particular, we show that the asymptotic symmetries of three-dimensional de Sitter space are in one-to-one correspondence with cosmological adiabatic modes for the curvature perturbation. In 2+1 dimensions, the asymptotic symmetry algebra is infinite-dimensional, given by two copies of the Virasoro algebra, and can be traced to the conformal symmetries of the two-dimensional spatial slices of de Sitter. We study the consequences of this infinite-dimensional symmetry for inflationary correlation functions, finding new soft theorems that hold only in 2+1 dimensions. Expanding the correlation functions as a power series in the soft momentum $q$, these relations constrain the traceless part of the tensorial coefficient at each order in $q$ in terms of a lower-point function. As a check, we verify that the ${\cal O}(q^2)$ identity is satisfied by inflationary correlation functions in the limit of small sound speed.
PLANETESIMAL DISK MICROLENSING

Motivated by debris disk studies, we investigate the gravitational microlensing of background starlight by a planetesimal disk around a foreground star. We use dynamical survival models to construct a plausible example of a planetesimal disk and study its microlensing properties using established ideas of microlensing by small bodies. When a solar-type source star passes behind a planetesimal disk, the microlensing light curve may exhibit short-term, low-amplitude residuals caused by planetesimals several orders of magnitude below Earth mass. The minimum planetesimal mass probed depends on the photometric sensitivity and the size of the source star, and is lower when the planetesimal lens is located closer to us. Planetesimal lenses may be found more nearby than stellar lenses because the steepness of the planetesimal mass distribution changes how the microlensing signal depends on the lens/source distance ratio. Microlensing searches for planetesimals require essentially continuous monitoring programs that are already feasible and can potentially set constraints on models of debris disks, the progeny of the supposed extrasolar analogues of Kuiper Belts.
Laboratory transferability of optimally shaped laser pulses for quantum control

Optimal control experiments can readily identify effective shaped laser pulses, or “photonic reagents,” that achieve a wide variety of objectives. An important additional practical desire is for photonic reagent prescriptions to produce good, if not optimal, objective yields when transferred to a different system or laboratory. Building on general experience in chemistry, the hope is that transferred photonic reagent prescriptions may remain functional even though all features of a shaped pulse profile at the sample typically cannot be reproduced exactly. As a specific example, we assess the potential for transferring optimal photonic reagents for the objective of optimizing a ratio of photoproduct ions from a family of halomethanes through three related experiments. First, applying the same set of photonic reagents with systematically varying second- and third-order chirp on both laser systems generated similar shapes of the associated control landscape (i.e., relation between the objective yield and the variables describing the photonic reagents). Second, optimal photonic reagents obtained from the first laser system were found to still produce near optimal yields on the second laser system. Third, transferring a collection of photonic reagents optimized on the first laser system to the second laser system reproduced systematic trends in photoproduct yields upon interaction with the homologous chemical family. These three transfers of photonic reagents are demonstrated to be successful upon paying reasonable attention to overall laser system characteristics. The ability to transfer photonic reagents from one laser system to another is analogous to well-established utilitarian operating procedures with traditional chemical reagents. The practical implications of the present results for experimental quantum control are discussed.
Magic of high-order van Hove singularity

The van Hove singularity in density of states generally exists in periodic systems due to the presence of saddle points of energy dispersion in momentum space. We introduce a new type of van Hove singularity in two dimensions, resulting from high-order saddle points and exhibiting power-law divergent density of states. We show that high-order van Hove singularity can be generally achieved by tuning the band structure with a single parameter in moire superlattices, such as twisted bilayer graphene by tuning twist angle or applying pressure, and trilayer graphene by applying vertical electric field. Correlation effects from high-order van Hove singularity near Fermi level are also discussed.
Few-Body Systems in Condensed Matter Physics

This review focuses on the studies and computations of few-body systems of electrons and holes in condensed matter physics. We analyze and illustrate the application of a variety of methods for description of two- three- and four-body excitonic complexes such as an exciton, trion and biexciton in three-, two- and one-dimensional configuration spaces in various types of materials. We discuss and analyze the contributions made over the years to understanding how the reduction of dimensionality affects the binding energy of excitons, trions and biexcitons in bulk and low-dimensional semiconductors and address the challenges that still remain.
UNCONVENTIONAL QUANTUM CRITICAL POINTS

In this paper we review the theory of unconventional quantum critical points that are beyond the Landau's paradigm. Three types of unconventional QCPs will be discussed: (1) The transition between topological order and semiclassical spin ordered phase; (2) The transition between topological order and valence bond solid phase; (3) The direct second order transition between different competing orders. We focus on the field theory and universality class of these unconventional QCPs. Relation of these QCPs with recent numerical simulations and experiments on quantum frustrated magnets are also discussed.
Standard norm varieties for Milnor symbols mod p

We prove that the standard norm varieties for Milnor symbols mod p of length n are birationally isomorphic to Pfister quadrics when p = 2, to Severi–Brauer varieties when p > 2 and n = 2, and to varieties defined by reduced norms of cyclic algebras when p > 2 and n = 3. In the case p = 2 and the case p > 2 and n = 2, the results imply that the standard norm varieties for two equal Milnor symbols mod p are birationally isomorphic, and we conjecture this in general.
The las campanas distant cluster survey - the catalog

We present an optically selected catalog of 1073 galaxy cluster and group candidates at 0.3 z 1. These candidates are drawn from the Las Campanas Distant Clusters Survey (LCDCS), a drift-scan imaging survey of a 130 square degree strip of the southern sky. To construct this catalog we utilize a novel detection process in which clusters are detected as positive surface brightness fluctuations in the background sky. This approach permits us to find clusters with significantly shallower data than other matched-filter methods that are based upon number counts of resolved galaxies. Selection criteria for the survey are fully automated so that this sample constitutes a well-defined, homogeneous sample that can be used to address issues of cluster evolution and cosmology. Estimated redshifts are derived for the entire sample, and an observed correlation between surface brightness and velocity dispersion, σ, is used to estimate the limiting velocity dispersion of the survey as a function of redshift. We find a net surface density of 15.5 candidates per square degree at zest ≥ 0.3, with a false-detection rate of ~30%. At z ~ 0.3 we probe down to the level of poor groups while by z ~ 0.8 we detect only the most massive systems (σ 1000 km s-1). We also present a supplemental catalog of 112 candidates that fail one or more of the automated selection criteria, but appear from visual inspection to be bona fide clusters.
Graph rules for the linked cluster expansion of the Legendre effective action

Graph rules for the linked cluster expansion of the Legendre effective action Γ[ϕ] are derived and proven in D ≥ 2 Euclidean dimensions. A key aspect is the weight assigned to articulation vertices which is itself shown to be computable from labeled tree graphs. The hopping interaction is allowed to be long ranged and scale dependent, thereby producing an in principle exact solution of Γ[ϕ]’s functional renormalization group equation.Graph rules for the linked cluster expansion of the Legendre effective action Γ[ϕ] are derived and proven in D ≥ 2 Euclidean dimensions. A key aspect is the weight assigned to articulation vertices which is itself shown to be computable from labeled tree graphs. The hopping interaction is allowed to be long ranged and scale dependent, thereby producing an in principle exact solution of Γ[ϕ]’s functional renormalization group equation.
Sound Speed in a Random Flow and Turbulent Shifts of the Solar Eigenfrequencies

Perturbation theory is used to calculate the frequency shift of acoustic modes of a homogeneous turbulent fluid and the frequency shifts of solar modes due to turbulent convection. For sound waves in a random flow, the fractional frequency shift is +(11/30)M2 in the long-wavelength limit, and the shift at short wavelengths is -2/3M2, where M is the average Mach number of the flow. In our model of solar convection, the low-degree f-mode shift is positive and unobservably small, whereas the fractional frequency shift at high degrees (l 500) is -M2, where M is the Mach number of convection near the solar surface.
Sequential monitoring of response-adaptive randomized clinical trials

Clinical trials are complex and usually involve multiple objectives such as controlling type I error rate, increasing power to detect treatment difference, assigning more patients to better treatment, and more. In literature, both response-adaptive randomization (RAR) procedures (by changing randomization procedure sequentially) and sequential monitoring (by changing analysis procedure sequentially) have been proposed to achieve these objectives to some degree. In this paper, we propose to sequentially monitor response-adaptive randomized clinical trial and study it’s properties. We prove that the sequential test statistics of the new procedure converge to a Brownian motion in distribution. Further, we show that the sequential test statistics asymptotically satisfy the canonical joint distribution defined in Jennison and Turnbull (2000). Therefore, type I error and other objectives can be achieved theoretically by selecting appropriate boundaries. These results open a door to sequentially monitor response-adaptive randomized clinical trials in practice. We can also observe from the simulation studies that, the proposed procedure brings together the advantages of both techniques, in dealing with power, total sample size and total failure numbers, while keeps the type I error. In addition, we illustrate the characteristics of the proposed procedure by redesigning a well-known clinical trial of maternal-infant HIV transmission.
Geometric scalings for the electrostatically driven helical plasma state

A new plasma state has been investigated [Akcay et al., Phys. Plasmas 24, 052503 (2017)], with a uniform applied axial magnetic field in a periodic cylinder of length L = 2 π R, driven by helical electrodes. The drive is single helicity, depending on m θ + k z = m θ − n ζ, where ζ = z / R and k = − n / R. For strong ( m , n ) = ( 1 , 1 ) drive, the state was found to have a strong axial mean current density, with a mean-field safety factor q 0 ( r ) just above the pitch of the electrodes m / n = 1 in the interior. This state has possible applications to DC electrical transformers and tailoring of the current profile in tokamaks. We study two geometric issues of interest for these applications: (i) scaling of properties with the plasma length or aspect ratio and (ii) behavior for different helicities, specifically ( m , n ) = ( 1 , n ) for n > 1 and ( m , n ) = ( 2 , 1 ).
PONDEROMOTIVE ACCELERATION IN CORONAL LOOPS

Ponderomotive acceleration has been asserted to be a cause of the First Ionization Potential (FIP) effect, the by now well known enhancement in abundance by a factor of 3-4 over photospheric values of elements in the solar corona with FIP less than about 10 eV. It is shown here by means of numerical simulations that ponderomotive acceleration occurs in solar coronal loops, with the appropriate magnitude and direction, as a "byproduct" of coronal heating. The numerical simulations are performed with the HYPERION code, which solves the fully compressible three-dimensional magnetohydrodynamic equations including nonlinear thermal conduction and optically thin radiation. Numerical simulations of a coronal loops with an axial magnetic field from 0.005 Teslas to 0.02 Teslas and lengths from 25000 km to 75000 km are presented. In the simulations the footpoints of the axial loop magnetic field are convected by random, large-scale motions. There is a continuous formation and dissipation of field-aligned current sheets which act to heat the loop. As a consequence of coronal magnetic reconnection, small scale, high speed jets form. The familiar vortex quadrupoles form at reconnection sites. Between the magnetic footpoints and the corona the reconnection flow merges with the boundary flow. It is in this region that the ponderomotive acceleration occurs. Mirroring the character of the coronal reconnection, the ponderomotive acceleration is also found to be intermittent.
Uncertainty principle in loop quantum cosmology by Moyal formalism

In this paper, we derive the uncertainty principle for the loop quantum cosmology homogeneous and isotropic Friedmann-Lemaiter-Robertson-Walker model with the holonomy-flux algebra. The uncertainty principle is between the variables c, with the meaning of connection and μ having the meaning of the physical cell volume to the power 2/3, i.e., v2/3 or a plaquette area. Since both μ and c are not operators, but rather the random variables, the Robertson uncertainty principle derivation that works for hermitian operators cannot be used. Instead we use the Wigner-Moyal-Groenewold phase space formalism. The Wigner-Moyal-Groenewold formalism was originally applied to the Heisenberg algebra of the quantum mechanics. One can derive it from both the canonical and path integral quantum mechanics as well as the uncertainty principle. In this paper, we apply it to the holonomy-flux algebra in the case of the homogeneous and isotropic space. Another result is the expression for the Wigner function on the space of the cylindrical wave functions defined on Rb in c variables rather than in dual space μ variables.
From Finite to Countable-Armed Bandits

We consider a stochastic bandit problem with countably many arms that belong to a finite set of types, each characterized by a unique mean reward. In addition, there is a fixed distribution over types which sets the proportion of each type in the population of arms. The decision maker is oblivious to the type of any arm and to the aforementioned distribution over types, but perfectly knows the total number of types occurring in the population of arms. We propose a fully adaptive online learning algorithm that achieves O(log n) distribution-dependent expected cumulative regret after any number of plays n, and show that this order of regret is best possible. The analysis of our algorithm relies on newly discovered concentration and convergence properties of optimism-based policies like UCB in finite-armed bandit problems with "zero gap," which may be of independent interest.
Heat Kernel Asymptotics of Operators with Non-Laplace Principal Part

We consider second-order elliptic partial differential operators acting on sections of vector bundles over a compact Riemannian manifold without boundary, working without the assumption of Laplace-like principal part -∇μ∇μ. Our objective is to obtain information on the asymptotic expansions of the corresponding resolvent and the heat kernel. The heat kernel and the Green's function are constructed explicitly in the leading order. The first two coefficients of the heat kernel asymptotic expansion are computed explicitly. A new semi-classical ansatz as well as the complete recursion system for the heat kernel of non-Laplace type operators is constructed. Some particular cases are studied in more detail.
Observational signature of tidal disruption of a star by a massive black hole

We have modeled the time-variable profiles of the Balmer alpha emission from the nonaxisymmetric disk and debris tail created in the tidal disruption of a solar-type star by a million solar mass black hole. Two tidal disruption events were simulated using a three dimensional relativistic smoothed particle hydrodynamic code to describe the early evolution of the debris during the first 50-90 days. We have calculated the physical conditions and radiative processes in the debris using the photoionization code CLOUDY. We model the emission-line profiles in the period immediately after the accretion rate onto the black hole becomes significant. We find that the line profiles at these very early stages of the evolution of the postdisruption debris do not resemble the double-peaked profiles expected from a rotating disk, since the debris has not yet settled into such a stable structure. As a result of the uneven distribution of the debris and the existence of a ``tidal tail'' (the stream of returning debris), the line profiles depend sensitively on the orientation of the tail relative to the line of sight. Moreover, the predicted line profiles vary on fairly short time scales (of order hours to days). Given the accretion rate onto the black hole we also model the Balmer alpha light curve from the debris.
Residues and tame symbols on toroidal varieties

We introduce a new approach to the study of a system of algebraic equations in the algebraic torus whose Newton polytopes have sufficiently general relative positions. Our method is based on the theory of Parshin's residues and tame symbols on toroidal varieties. It provides a uniform algebraic explanation of the recent result of Khovanskii on the product of the roots of such systems and the Gel'fond--Khovanskii result on the sum of the values of a Laurent polynomial over the roots of such systems, and extends them to the case of an algebraically closed field of arbitrary characteristic.
BINARY BLACK HOLE ACCRETION FROM A CIRCUMBINARY DISK: GAS DYNAMICS INSIDE THE CENTRAL CAVITY

We present the results of two-dimensional (2D) hydrodynamical simulations of circumbinary disk accretion using the finite-volume code DISCO. This code solves the 2D viscous Navier-Stokes equations on a high-resolution moving mesh which shears with the fluid flow, greatly reducing advection errors in comparison with a fixed grid. We perform a series of simulations for binary mass ratios in the range 0.026 ≤ q ≤ 1.0, each lasting longer than a viscous time so that we reach a quasi-steady accretion state. In each case, we find that gas is efficiently stripped from the inner edge of the circumbinary disk and enters the cavity along accretion streams, which feed persistent "mini disks" surrounding each black hole. We find that for q 0.1, the binary excites eccentricity in the inner region of the circumbinary disk, creating an overdense lump which gives rise to enhanced periodicity in the accretion rate. The dependence of the periodicity on mass ratio may provide a method for observationally inferring mass ratios from measurements of the accretion rate. We also find that for all mass ratios studied, the magnitude of the accretion onto the secondary is sufficient to drive the binary toward larger mass ratio. This suggests a mechanism for biasing mass-ratio distributions toward equal mass.
On the structure of Hermitian manifolds with semipositive Griffiths curvature

In this paper we establish partial structure results on the geometry of compact Hermitian manifolds of semipositive Griffiths curvature. We show that after appropriate arbitrary small deformation of the initial metric, the null spaces of the Chern-Ricci two-form generate a holomorphic, integrable distribution. This distribution induces an isometric, holomorphic, almost free action of a complex Lie group on the universal cover of the manifold. Our proof combines the strong maximum principle for the Hermitian Curvature Flow (HCF), new results on the interplay of the HCF and the torsion-twisted connection, and observations on the geometry of the torsion-twisted connection on a general Hermitian manifold.
Coil creep and skew-quadrupole field components in the Tevatron

During the first 20 years of operation, the Fermilab Tevatron developed strong coupling between the two transverse degrees of freedom. The required strength of the circuit of skew quadrupole magnets used to correct for coupling, though capable, had increased by an order of magnitude since 1983. Changes made to the Tevatron for colliding beams operation had altered the skew quadrupole corrector distribution and strong coupling became evident, often encumbering routine operation during the colliding beam physics run. It was discovered that the superconducting coils of the main dipole magnets had become vertically displaced relative to their yokes since their construction. The ensuing systematic skew quadrupole field introduced by this displacement accounts for the required corrector settings and observed beam behavior. The magnets were adjusted in situ over the course of several long maintenance periods and the Tevatron performance improved as a result.
Can Gravitational Collapse Sustain Singularity-Free Trapped Surfaces?

In singularity-generating space–times both the outgoing and the ingoing expansions of null geodesic congruences θ+ and θ- should become increasingly negative without bound, inside the horizon. This behavior leads to geodetic incompleteness, which in turn predicts the existence of a singularity. In this work we inquire whether, in gravitational collapse, space–time can sustain singularity-free trapped surfaces, in the sense that such a space–time remains geodetically complete. As a test case, we consider a type D space–time of Dymnikova which is Schwarzschild-like at large distances and consists of a fluid with a p = -ρ equation of state near r = 0. By following both the expansion parameters θ+ and θ- across the horizon and into the black hole, we find that both θ+ and θ+θ- have turning points inside the trapped region. Further, we find that deep inside the black hole there is a region, 0 ≤ r < r0 (which includes the black hole center), which is not trapped. Thus the trapped region is bounded from both outside and inside. The space–time is geodetically complete, a result which violates a condition for singularity formation. It is inferred that, in general, if gravitational collapse were to proceed with a p =-ρ fluid formation, the resulting black hole might be singularity-free.
Binary information propagation in circular magnetic nanodot arrays using strain induced magnetic anisotropy.

Nanomagnetic logic has emerged as a potential replacement for traditional Complementary Metal Oxide Semiconductor (CMOS) based logic because of superior energy-efficiency (Salahuddin and Datta 2007 Appl. Phys. Lett. 90 093503, Cowburn and Welland 2000 Science 287 1466–68). One implementation of nanomagnetic logic employs shape-anisotropic (e.g. elliptical) ferromagnets (with two stable magnetization orientations) as binary switches that rely on dipole−dipole interaction to communicate binary information (Cowburn and Welland 2000 Science 287 1466–8, Csaba et al 2002 IEEE Trans. Nanotechnol. 1 209–13, Carlton et al 2008 Nano Lett. 8 4173–8, Atulasimha and Bandyopadhyay 2010 Appl. Phys. Lett. 97 173105, Roy et al 2011 Appl. Phys. Lett. 99 063108, Fashami et al 2011 Nanotechnology 22 155201, Tiercelin et al 2011 Appl. Phys. Lett. 99 , Alam et al 2010 IEEE Trans. Nanotechnol. 9 348–51 and Bhowmik et al 2013 Nat. Nanotechnol. 9 59–63). Normally, circular nanomagnets are incompatible with this approach since they lack distinct stable in-plane magnetization orientations to encode bits. However, circular magnetoelastic nanomagnets can be made bi-stable with a voltage induced anisotropic strain, which provides two significant advantages for nanomagnetic logic applications. First, the shape-anisotropy energy barrier is eliminated which reduces the amount of energy required to reorient the magnetization. Second, the in-plane size can be reduced (~20 nm) which was previously not possible due to thermal stability issues. In circular magnetoelastic nanomagnets, a voltage induced strain stabilizes the magnetization even at this size overcoming the thermal stability issue. In this paper, we analytically demonstrate the feasibility of a binary 'logic wire' implemented with an array of circular nanomagnets that are clocked with voltage-induced strain applied by an underlying piezoelectric substrate. This leads to an energy-efficient logic paradigm orders of magnitude superior to existing CMOS-based logic that is scalable to dimensions substantially smaller than those for existing nanomagnetic logic approaches. The analytical approach is validated with experimental measurements conducted on dipole coupled Nickel (Ni) nanodots fabricated on a PMN-PT (Lead Magnesium Niobate-Lead Titanate) sample.
Optimal Target Stars in the Search for Life

The selection of optimal targets in the search for life represents a highly important strategic issue. In this paper, we evaluate the relative benefits of searching for life around a potentially habitable planet orbiting a star of arbitrary mass relative to a Sun-like star. If recent physical arguments implying that the habitability of planets orbiting low-mass stars is selectively suppressed are correct, we find that planets around solar-type stars may represent the optimal targets.
Algorithmic homeomorphism of 3-manifolds as a corollary of geometrization

In this paper we prove two results, one folklore and the other new. The folklore result, which goes back to Thurston, is that the geometrization theorem implies that there is an algorithm for the homeomorphism problem for closed, oriented, triangulated 3-manifolds. We give a self-contained proof, with several variations at each stage, that uses only the statement of the geometrization theorem, basic hyperbolic geometry, and old results from combinatorial topology and computer science. For this result, we do not rely on normal surface theory, methods from geometric group theory, nor methods used to prove geometrization. The new result is that the homeomorphism problem is elementary recursive, i.e., that the computational complexity is bounded by a bounded tower of exponentials. This result makes essential use of normal surface theory, Mostow rigidity, and improved bounds on the computational complexity of solving algebraic equations.
Smooth approximations of the conical Kähler–Ricci flows

In this note, we show that the conical Kahler–Ricci flows introduced in Chen and Wang (Bessel functions, Heat kernel and the conical Kahler–Ricci flow. J. Funct. Anal. 269(2), 2013) exist for all time \(t\in [0,\infty )\) in the weak sense as in Definition 1.2. As a key ingredient of the proof, we show that a conical Kahler–Ricci flow is actually the limit of a sequence of smooth Kahler–Ricci flows.
Propagation Modeling Through Foliage in a Coniferous Forest at 28 GHz

The goal of this letter is to investigate the propagation behavior of 28-GHz millimeter wave in coniferous forests and model its basic transmission loss. Field measurements were conducted with a custom-designed sliding correlator sounder. Relevant foliage regions were extracted from high-resolution LiDAR data and satellite images. Our results show that traditional foliage analysis models for lower-frequency wireless communications fail to consistently output correct path loss predictions. Novel fully automated site-specific models are proposed to resolve this issue, yielding 0.9 dB overall improvement and up to 20 dB regional improvement in root mean square errors.
PoMiN: A Post-Minkowskian N-body Solver

In this paper, we introduce , a lightweight N-body code based on the post-Minkowskian N-body Hamiltonian of Ledvinka et al., which includes general relativistic effects up to first order in Newton's constant G, and all orders in the speed of light c. is written in and uses a fourth-order Runge–Kutta integration scheme. has also been written to handle an arbitrary number of particles (both massive and massless), with a computational complexity that scales as O(N 2). We describe the methods we used to simplify and organize the Hamiltonian, and the tests we performed (convergence, conservation, and analytical comparison tests) to validate the code.
AGN Heating in Simulated Cool-core Clusters

We analyze heating and cooling processes in an idealized simulation of a cool-core cluster, where momentum-driven AGN feedback balances radiative cooling in a time-averaged sense. We find that, on average, energy dissipation via shock waves is almost an order of magnitude higher than via turbulence. Most of the shock waves in the simulation are very weak shocks with Mach numbers smaller than 1.5, but the stronger shocks, although rare, dissipate energy more effectively. We find that shock dissipation is a steep function of radius, with most of the energy dissipated within 30 kpc, while radiative cooling loses area less concentrated. However, adiabatic processes and mixing (of post-shock materials and the surrounding gas) are able to redistribute the heat throughout the core. A considerable fraction of the AGN energy also escapes the core region. The cluster goes through cycles of AGN outbursts accompanied by periods of enhanced precipitation and star formation, over Gyr timescales. The cluster core is under-heated at the end of each cycle, but over-heated at the peak of the AGN outburst. During the heating-dominant phase, turbulent dissipation alone is often able to balance radiative cooling at every radius but, when this is occurs, shock waves inevitably dissipate even more energy. Our simulation explains why some clusters, such as Abell 2029, are cooling dominated, while in some other clusters, such as Perseus, various heating mechanisms including shock heating, turbulent dissipation and bubble mixing can all individually balance cooling, and together, overheat the core.