cssi/SciSciGPT-SciSciNet huggingface dataset:
Heating of the Intracluster Gas in the Triangulum Australis Cluster

ASCA and ROSAT X-ray data are used to obtain two-dimensional maps of the gas temperature, pressure, and specific entropy in the Triangulum Australis cluster of galaxies. We find that this hot (Te = 10.3 ± 0.8 keV) system probably has a temperature peak (Te > 12 keV) at the cluster core, which approximately corresponds to the adiabatic relation. An underdense gas sector, found in the ROSAT cluster image eastward of the core, has a higher temperature than average at that radius. At this higher temperature, the gas pressure in this sector is equal to that of the rest of the cluster at the same radius, but the specific entropy of this gas is significantly higher (although the temperature difference itself is only marginally significant). We speculate that the existence of this region of underdense high-entropy gas, as well as the adiabatic central temperature peak, indicate recent or ongoing heating of the intergalactic medium in this cluster. The most probable source of such heating is a subcluster merger, for which the hydrodynamic simulations predict a qualitatively similar temperature structure. We point out that entropy maps can provide a physically meaningful way of diagnosing merging clusters and comparing the predictions of merger simulations to the data.
Simultaneous Magnetic Polar Cap Heating during a Flaring Episode from the Magnetar 1RXS J170849.0-400910

During a pointed 2018 NuSTAR observation, we detected a flare with a 2.2 hr duration from the magnetar 1RXS J170849.0−400910. The flare, which rose in ~25 s to a maximum flux 6 times larger than the persistent emission, is highly pulsed with an rms pulsed fraction of 53%. The pulse profile shape consists of two peaks separated by half a rotational cycle, with a peak flux ratio of ~2. The flare spectrum is thermal with an average temperature of 2.1 keV. Phase-resolved spectroscopy shows that the two peaks possess the same temperature, but differ in size. These observational results, along with simple light curve modeling, indicate that two identical antipodal spots, likely the magnetic poles, are heated simultaneously at the onset of the flare and for its full duration. Hence, the origin of the flare has to be connected to the global dipolar structure of the magnetar. This might best be achieved externally, via twists to closed magnetospheric dipolar field lines seeding bombardment of polar footpoint locales with energetic pairs. Approximately 1.86 hr following the onset of the flare, a short burst with its own 3 minutes thermal tail occurred. The burst tail is also pulsating at the spin period of the source and phase-aligned with the flare profile, implying an intimate connection between the two phenomena. The burst may have been caused by a magnetic reconnection event in the same twisted dipolar field lines anchored to the surface hot spots, with subsequent return currents supplying extra heat to these polar caps.
Non-cyclotomic fusion categories

Etingof, Nikshych and Ostrik ask in [7, §2] if every fusion category can be completely defined over a cyclotomic field. We show that this is not the case: in particular one of the fusion categories coming from the Haagerup subfactor [1] and one coming from the newly constructed extended Haagerup subfactor [2] can not be completely defined over a cyclotomic field. On the other hand, we show that the Drinfel’d center of the even part of the Haagerup subfactor is completely defined over a cyclotomic field. We identify the minimal field of definition for each of these fusion categories, compute the Galois groups, and identify their Galois conjugates. AMS Classification 18D10 ; 46L37
Anomaly Inflow, Accidental Symmetry, and Spontaneous Symmetry Breaking

We consider the 6d (1,0) SCFT on a stack of N M5-branes probing a ℂ2/ℤ2 singularity. In particular, we study its compactifications to four dimensions on a smooth genus-g Riemann surface with non-trivial flavor flux, yielding a family of 4d CFTs. By tracking the M-theory origin of the global symmetries of the 4d CFTs, we detect the emergence of an accidental symmetry and the spontaneous symmetry breaking of a U(1) generator. These effects are visible from geometric considerations and not apparent from the point of view of the compactification of the 6d field theory. These phenomena leave an imprint on the ’t Hooft anomaly polynomial of the 4d CFTs, which is obtained from recently developed anomaly inflow methods in M-theory [1]. In the large-N limit, we identify the gravity dual of the 4d setups to be a class of smooth AdS5 solutions first discussed by Gauntlett-Martelli-Sparks-Waldram. Using our anomaly polynomial, we compute the conformal central charge and a non-Abelian flavor central charge at large N , finding agreement with the holographic predictions.
Searching for proto-brown dwarfs: Extending near IR spectroscopy of protostars below the hydrogen burning limit†

Recent observations of nearby star forming regions have offered evidence that young brown dwarfs undergo a period of mass accretion analogous to the T Tauri phase observed in young stars. Brown dwarf analogs to stellar protostars, however, have yet to be definitively observed. These young, accreting objects would shed light on the nature of the dominant brown dwarf formation process, as well as provide ideal laboratories to investigate the dependence of the accretion mechanism on protostellar mass. Recent near infrared surveys have identified candidate proto-brown dwarfs and characterized low mass protostars in nearby star forming regions. These techniques allow near infrared spectra to diagnose the effective temperature, accretion luminosity, magnetic field strength and rotation velocity of young low mass stars across the stellar/substellar boundary. The lowest mass proto-brown dwarfs (M < 40 MJup), however, will prove challenging to observe given current near IR observational capabilities. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Tsallis Entropy Composition and the Heisenberg Group

We present an embedding of the Tsallis entropy into the three-dimensional Heisenberg group, in order to understand the meaning of generalized independence as encoded in the Tsallis entropy composition property. We infer that the Tsallis entropy composition induces fractal properties on the underlying Euclidean space. Using a theorem of Milnor/Wolf/Tits/Gromov, we justify why the underlying configuration/phase space of systems described by the Tsallis entropy has polynomial growth for both discrete and Riemannian cases. We provide a geometric framework that elucidates Abe's formula for the Tsallis entropy, in terms the Pansu derivative of a map between sub-Riemannian spaces.
On the Whitehead Spectrum of the Circle

The seminal work of Waldhausen, Farrell and Jones, Igusa, and Weiss andWilliams shows that the homotopy groups in low degrees of the space of homeomorphisms of a closed Riemannian manifold of negative sectional curvature can be expressed as a functor of the fundamental group of the manifold. To determine this functor, however, it remains to determine the homotopy groups of the topological Whitehead spectrum of the circle. The cyclotomic trace of Bokstedt, Hsiang, and Madsen and a theorem of Dundas, in turn, lead to an expression for these homotopy groups in terms of the equivariant homotopy groups of the homotopy fiber of the map from the topological Hochschild T-spectrum of the sphere spectrum to that of the ring of integers induced by the Hurewicz map. We evaluate the latter homotopy groups, and hence, the homotopy groups of the topologicalWhitehead spectrum of the circle in low degrees. The result extends earlier work by Anderson and Hsiang and by Igusa and complements recent work by Grunewald, Klein, and Macko.
Shape estimation for elongated deformable object using B-spline chained multiple random matrices model

In this paper, a B-spline chained multiple random matrix models (RMMs) representation is proposed to model geometric characteristics of an elongated deformable object. The hyper degrees of freedom structure of the elongated deformable object make its shape estimation challenging. Based on the likelihood function of the proposed B-spline chained multiple RMMs, an expectation-maximization (EM) method is derived to estimate the shape of the elongated deformable object. A split and merge method based on the Euclidean minimum spanning tree (EMST) is proposed to provide initialization for the EM algorithm. The proposed algorithm is evaluated for the shape estimation of the elongated deformable objects in scenarios, such as the static rope with various configurations (including configurations with intersection), the continuous manipulation of a rope and a plastic tube, and the assembly of two plastic tubes. The execution time is computed and the accuracy of the shape estimation results is evaluated based on the comparisons between the estimated width values and its ground-truth, and the intersection over union (IoU) metric.
Plasmonic cloaking of cylinders: Finite length, oblique illumination and cross-polarization coupling

Metamaterial cloaking has been proposed and studied in recent years by following several interesting approaches. One of them, the scattering-cancelation technique or plasmonic cloaking, exploits the plasmonic effects of suitably designed thin homogeneous metamaterial covers to drastically suppress the scattering of moderately sized objects within specific frequency ranges of interest. In addition to its inherent simplicity, this technique also holds the promise of an isotropic response and weak polarization dependence. Its theory has been applied extensively to symmetrical geometries and canonical three-dimensional (3D) shapes, but the application of it to elongated objects has not been explored with the same level of detail. We derive here closed-form theoretical formulae for infinitely long cylinders under arbitrary wave incidence, and validate their performance with full-wave numerical simulations, also considering the effects of finite lengths and truncation effects in cylindrical objects. In particular, we find that a single isotropic (idealized) cloaking layer may successfully suppress the dominant scattering coefficients of moderately thin elongated objects, even for finite lengths comparable with the incident wavelength, providing weak dependence on the incidence angle. These results may pave the way for application of plasmonic cloaking in a variety of practical scenarios of interest.
Notes on Perelman's papers

e Conjecture, and more generally Thurston’s Geometrization Conjecture, using the Ricci flow approach of Hamilton. Perelman’s proofs are concise and, at times, sketchy. The purpose of these notes is to provide the details that are missing in [46] and [47], which contain Perelman’s arguments for the Geometrization Conjecture. Among other things, we cover the construction of the Ricci flow with surgery of [47]. We also discuss the long-time behavior of the Ricci flow with surgery, which is needed for the full Geometrization Conjecture. The papers of Colding and Minicozzi [23; 24] and Perelman [48], which are not covered in these notes, each provide a shortcut in the case of the Poincar´ e Conjecture. Namely, these papers show that if the initial manifold is simply-connected then the Ricci flow with surgery becomes extinct in a finite time, thereby removing the issue of the long-time behavior. Combining this claim with the proof of existence of Ricci flow with surgery gives the shortened proof in the simply-connected case. These notes are intended for readers with a solid background in geometric analysis. Good sources for background material on Ricci flow are Chow and Knopf [21], Chow, Lu and Ni [22], Hamilton [30] and Topping [60]. The notes are self-contained but are designed to be read along with [46; 47]. For the most part we follow the format of [46; 47] and use the section numbers of [46; 47] to label our sections. We have done this in
A higher-derivative Lee-Wick standard model

The Lee-Wick Standard Model assumes a minimal set of higher-derivative quadratic terms that produce a negative-norm partner for each Standard Model particle. Here we introduce additional terms of one higher order in the derivative expansion that give each Standard Model particle two Lee-Wick partners: one with negative and one with positive norm. These states collectively cancel unwanted quadratic divergences and resolve the hierarchy problem as in the minimal theory. We show how this next-to-minimal higher-derivative theory may be reformulated via an auxiliary field approach and written as a Lagrangian with interactions of dimension four or less. This mapping provides a convenient framework for studies of the formal and phenomenological properties of the theory.
NUCLEON FORM FACTORS PROGRAM WITH SBS AT JLAB

The physics of the nucleon form factors is the basic part of the Jefferson Laboratory program. We review the achievements of the 6-GeV era and the program with the 12-GeV beam with the SBS spectrometer in Hall A, with a focus on the nucleon ground state properties.
All one needs to know about fog computing and related edge computing paradigms: A complete survey

Abstract With the Internet of Things (IoT) becoming part of our daily life and our environment, we expect rapid growth in the number of connected devices. IoT is expected to connect billions of devices and humans to bring promising advantages for us. With this growth, fog computing, along with its related edge computing paradigms, such as multi-access edge computing (MEC) and cloudlet, are seen as promising solutions for handling the large volume of security-critical and time-sensitive data that is being produced by the IoT. In this paper, we first provide a tutorial on fog computing and its related computing paradigms, including their similarities and differences. Next, we provide a taxonomy of research topics in fog computing, and through a comprehensive survey, we summarize and categorize the efforts on fog computing and its related computing paradigms. Finally, we provide challenges and future directions for research in fog computing.
Dislocations and grain boundaries in two-dimensional boron nitride.

A new dislocation structure—square-octagon pair (4|8) is discovered in two-dimensional boron nitride (h-BN), via first-principles calculations. It has lower energy than corresponding pentagon–heptagon pairs (5|7), which contain unfavorable homoelemental bonds. On the basis of the structures of dislocations, grain boundaries (GB) in BN are investigated. Depending on the tilt angle of grains, GB can be either polar (B-rich or N-rich), constituted by 5|7s, or unpolar, composed of 4|8s. The polar GBs carry net charges, positive at B-rich and negative at N-rich ones. In contrast to GBs in graphene which generally impede the electronic transport, polar GBs have a smaller bandgap compared to perfect BN, which may suggest interesting electronic and optical applications.
How Much Knowledge Can You Pack Into the Parameters of a Language Model

It has recently been observed that neural language models trained on unstructured text can implicitly store and retrieve knowledge using natural language queries. In this short paper, we measure the practical utility of this approach by fine-tuning pre-trained models to answer questions without access to any external context or knowledge. We show that this approach scales with model size and performs competitively with open-domain systems that explicitly retrieve answers from an external knowledge source when answering questions. To facilitate reproducibility and future work, we release our code and trained models.
Prediction uncertainty and optimal experimental design for learning dynamical systems

Dynamical systems are frequently used to model biological systems. When these models are fit to data, it is necessary to ascertain the uncertainty in the model fit. Here, we present prediction deviation, a metric of uncertainty that determines the extent to which observed data have constrained the model's predictions. This is accomplished by solving an optimization problem that searches for a pair of models that each provides a good fit for the observed data, yet has maximally different predictions. We develop a method for estimating a priori the impact that additional experiments would have on the prediction deviation, allowing the experimenter to design a set of experiments that would most reduce uncertainty. We use prediction deviation to assess uncertainty in a model of interferon-alpha inhibition of viral infection, and to select a sequence of experiments that reduces this uncertainty. Finally, we prove a theoretical result which shows that prediction deviation provides bounds on the trajectories of the underlying true model. These results show that prediction deviation is a meaningful metric of uncertainty that can be used for optimal experimental design.
Complementary Quantum Logic Family Using Josephson Junctions and Quantum Phase-Slip Junctions

In this paper, we explore a new set of circuits that incorporate both single-flux-quantum and quantized charge-based complementary quantum logic circuits. Circuits that convert single-flux quantum voltage pulses to quantized charge pulses and vice versa, leading to circuits that simplify logic and integration operations of individual flux and charge-based logic circuits, are introduced. These include fan-out circuits that enable single flux input to several charge outputs as well as control gate circuit with charge input controlling flux output. The operation of these circuits is demonstrated in simulations using WRSPICE. An XOR gate implementation is presented as an example to illustrate the operation of these circuits. The developed complementary quantum logic circuits show promise for higher power efficiency and simpler design in the form of fewer junctions for a given logic implementation, leading to the possibility of higher integration density.
A molecular dynamics simulation of DNA damage induction by ionizing radiation.

We present a multi-scale simulation of the early stage of DNA damages by the indirect action of hydroxyl ((•)OH) free radicals generated by electrons and protons. The computational method comprises of interfacing the Geant4-DNA Monte Carlo with ReaxFF molecular dynamics software. A clustering method was employed to map the coordinates of (•)OH-radicals extracted from the ionization-track-structures onto nano-meter simulation voxels filled with DNA and water molecules. The molecular dynamics simulation provides the time-evolution and chemical reactions in individual simulation voxels as well as the energy-landscape accounted for the DNA-(•)OH chemical reaction that is essential for the first-principle enumeration of hydrogen abstractions, chemical bond breaks, and DNA-lesions induced by collection of ions in clusters less than the critical dimension which is approximately 2-3 A. We show that the formation of broken bonds leads to DNA-base and backbone damages that collectively propagate to DNA single and double-strand breaks. For illustration of the methodology, we focused on particles with an initial energy of 1 MeV. Our studies reveal a qualitative difference in DNA damage induced by low energy electrons and protons. Electrons mainly generate small pockets of (•)OH-radicals, randomly dispersed in the cell volume. In contrast, protons generate larger clusters along a straight-line parallel to the direction of the particle. The ratio of the total DNA double-strand breaks induced by a single proton and electron track is determined to be ≈4 in the linear scaling limit. In summary, we have developed a multi-scale computational model based on first-principles to study the interaction of ionizing radiation with DNA molecules. The main advantage of our hybrid Monte Carlo approach using Geant4-DNA and ReaxFF is the multi-scale simulation of the cascade of both physical and chemical events which result in the formation of biological damage. The tool developed in this work can be used in the future to investigate the relative biological effectiveness of light and heavy ions that are used in radiotherapy.
SIMILARITIES IN POPULATIONS OF STAR CLUSTERS

We compare the observed mass functions and age distributions of star clusters in six well-studied galaxies: the Milky Way, Magellanic Clouds, M83, M51, and Antennae. In combination, these distributions span wide ranges of mass and age: 102 M/M ☉ 106 and 106 τ/yr 109. We confirm that the distributions are well represented by power laws: dN/dMM β with β –1.9 and dN/dττγ with γ –0.8. The mass and age distributions are approximately independent of each other, ruling out simple models of mass-dependent disruption. As expected, there are minor differences among the exponents at a level close to the true uncertainties, β ~ γ ~ 0.1-0.2. However, the overwhelming impression is the similarity of the mass functions and age distributions of clusters in these different galaxies, including giant and dwarf, quiescent and interacting galaxies. This is an important empirical result, justifying terms such as universal or quasi-universal. We provide a partial theoretical explanation for these observations in terms of physical processes operating during the formation and disruption of the clusters, including star formation and feedback, subsequent stellar mass loss, and tidal interactions with passing molecular clouds. A full explanation will require additional information about the molecular clumps and star clusters in galaxies beyond the Milky Way.
The R -parity violating decays of charginos and neutralinos in the B-L MSSM

The B − L MSSM is the MSSM with three right-handed neutrino chiral multiplets and gauged B − L symmetry. The B − L symmetry is broken by the third family right-handed sneutrino acquiring a VEV, thus spontaneously breaking R-parity. Within a natural range of soft supersymmetry breaking parameters, it is shown that a large and uncorrelated number of initial values satisfy all present phenomenological constraints; including the correct masses for the W±, Z0 bosons, having all sparticles exceeding their present lower bounds and giving the experimentally measured value for the Higgs boson. For this “valid” set of initial values, there are a number of different LSPs, each occurring a calculable number of times. We plot this statistically and determine that among the most prevalent LSPs are chargino and neutralino mass eigenstates. In this paper, the R-parity violating decay channels of charginos and neutralinos to standard model particles are determined, and the interaction vertices and decay rates computed analytically. These results are valid for any chargino and neutralino, regardless of whether or not they are the LSP. For chargino and neutralino LSPs, we will — in a subsequent series of papers — present a numerical study of their RPV decays evaluated statistically over the range of associated valid initial points.
Comment: Boosting Algorithms: Regularization, Prediction and Model Fitting

We congratulate the authors (hereafter BH) for an interesting take on the boosting technology, and for developing a modular computational environment in R for exploring their models. Their use of low-degree-offreedom smoothing splines as a base learner provides an interesting approach to adaptive additive modeling. The notion of “Twin Boosting” is interesting as well; besides the adaptive lasso, we have seen the idea applied more directly for the lasso and Dantzig selector (James, Radchenko and Lv, 2007). In this discussion we elaborate on the connections between L2-boosting of a linear model and infinitesimal forward stagewise linear regression. We then take the authors to task on their definition of degrees of freedom.
Exact transition probabilities in the three-state Landau–Zener–Coulomb model

We obtain the exact expression for the matrix of nonadiabatic transition probabilities in the model of three interacting states with a time-dependent Hamiltonian. Unlike other known solvable Landau–Zener-like problems, our solution is generally expressed in terms of hypergeometric functions that have relatively complex behavior, e.g. the obtained transition probabilities may show multiple oscillations as functions of parameters of the model Hamiltonian.
Search for neutrinoless double beta decay

We review current experimental efforts to search for neutrinoless double beta decay (0νββ). A description of the selected leading experiments is given and the strongest recent results are compared in terms of achieved background indexes (BI) and limits on effective Majorana mass. A combined limit is also shown. The second part of the review covers next generation experiments, highlighting the challenges and new technologies that may be necessary to achieve a justifiable discovery potential. A potential synergy with direct dark matter searches, which could be an especially prudent strategy in case the axial vector coupling constant is quenched in 0νββ decay, is emphasized.
Random Triangles and Polygons in the Plane

In 1997, Jean-Claude Hausmann and Allen Knutson introduced a natural and beautiful correspondence between planar n-gons and the Grassmann manifold of 2-planes in real n-space. This construction lea...
New nonlinear hyperbolic groups

We construct nonlinear hyperbolic groups which are large, torsion-free, one-ended, and admit a finite $K(\pi,1)$. Our examples are built from superrigid cocompact rank one lattices via amalgamated free products and HNN extensions.
Particle acceleration during magnetic reconnection in a low-beta pair plasma

Plasma energization through magnetic reconnection in the magnetically dominated regime featured by low plasma beta ( β=8πnkT0/B2≪1) and/or high magnetization ( σ=B2/(4πnmc2)≫1) is important in a series of astrophysical systems such as solar flares, pulsar wind nebula, and relativistic jets from black holes. In this paper, we review the recent progress on kinetic simulations of this process and further discuss plasma dynamics and particle acceleration in a low-β reconnection layer that consists of electron–positron pairs. We also examine the effect of different initial thermal temperatures on the resulting particle energy spectra. While earlier papers have concluded that the spectral index is smaller for higher σ, our simulations show that the spectral index approaches p = 1 for sufficiently low plasma β, even if σ∼1. Since this predicted spectral index in the idealized limit is harder than most observations, it is important to consider effects that can lead to a softer spectrum such as open boundary simul...
MHOs toward HMOs: A Search for Molecular Hydrogen Emission-Line Objects toward High-mass Outflows

We present the results of a narrow-band near-infrared imaging survey for Molecular Hydrogen emission-line Objects (MHOs) toward 26 regions containing high-mass protostellar candidates and massive molecular outflows. We have detected a total of 236 MHOs, 156 of which are new detections, in 22 out of the 26 regions. We use H2 2.12 μm/H2 2.25 μm flux ratios, together with morphology, to separate the signatures of fluorescence associated with photo-dissociation regions (PDRs) from shocks associated with outflows in order to identify the MHOs. PDRs have typical low flux ratios of ~1.5–3, while the vast majority of MHOs display flux ratios typical of C-type shocks (~6–20). A few MHOs exhibit flux ratios consistent with expected values for J-type shocks (~3–4), but these are located in regions that may be contaminated with fluorescent emission. Some previously reported MHOs have low flux ratios, and are likely parts of PDRs rather than shocks indicative of outflows. We identify a total of 36 outflows across the 22 target regions where MHOs were detected. In over half these regions, MHO arrangements and fluorescent structures trace features present in CO outflow maps, suggesting that the CO emission traces a combination of dynamical effects, which may include gas entrained in expanding PDRs as well as bipolar outflows. Where possible, we link MHO complexes to distinct outflows and identify candidate driving sources.
RESONANT REMOVAL of EXOMOONS during PLANETARY MIGRATION

Jupiter and Saturn play host to an impressive array of satellites, making it reasonable to suspect that similar systems of moons might exist around giant extrasolar planets. Furthermore, a significant population of such planets is known to reside at distances of several Astronomical Units (AU), leading to speculation that some moons thereof might support liquid water on their surfaces. However, giant planets are thought to undergo inward migration within their natal protoplanetary disks, suggesting that gas giants currently occupying their host star's habitable zone formed farther out. Here we show that when a moon-hosting planet undergoes inward migration, dynamical interactions may naturally destroy the moon through capture into a so-called evection resonance. Within this resonance, the lunar orbit's eccentricity grows until the moon eventually collides with the planet. Our work suggests that moons orbiting within about ~10 planetary radii are susceptible to this mechanism, with the exact number dependent on the planetary mass, oblateness, and physical size. Whether moons survive or not is critically related to where the planet began its inward migration, as well as the character of interlunar perturbations. For example, a Jupiter-like planet currently residing at 1 AU could lose moons if it formed beyond ~5 AU. Cumulatively, we suggest that an observational census of exomoons could potentially inform us on the extent of inward planetary migration, for which no reliable observational proxy currently exists.
Parallel Electric Field Spectrum of Solar Wind Turbulence

By searching through more than 10 satellite years of THEMIS and Cluster data, 3 reliable examples of parallel electric field turbulence in the undisturbed solar wind have been found. The perpendicular and parallel electric field spectra in these examples have similar shapes and amplitudes, even at large scales (frequencies below the ion gyroscale), where Alfvenic turbulence with no parallel electric field component is thought to dominate. The spectra of the parallel electric field fluctuations are power laws with exponents near –5/3 below the ion scales (~0.1 Hz), and with a flattening of the spectrum in the vicinity of this frequency. At small scales (above a few Hz), the spectra are steeper than –5/3 with values in the range of –2.1 to –2.8. These steeper slopes are consistent with expectations for kinetic Alfven turbulence, although their amplitude relative to the perpendicular fluctuations is larger than expected.
D4M: Bringing associative arrays to database engines

The ability to collect and analyze large amounts of data is a growing problem within the scientific community. The growing gap between data and users calls for innovative tools that address the challenges faced by big data volume, velocity and variety. Numerous tools exist that allow users to store, query and index these massive quantities of data. Each storage or database engine comes with the promise of dealing with complex data. Scientists and engineers who wish to use these systems often quickly find that there is no single technology that offers a panacea to the complexity of information. When using multiple technologies, however, there is significant trouble in designing the movement of information between storage and database engines to support an end-to-end application along with a steep learning curve associated with learning the nuances of each underlying technology. In this article, we present the Dynamic Distributed Dimensional Data Model (D4M) as a potential tool to unify database and storage engine operations. Previous articles on D4M have showcased the ability of D4M to interact with the popular NoSQL Accumulo database. Recently however, D4M now operates on a variety of backend storage or database engines while providing a federated look to the end user through the use of associative arrays. In order to showcase how new databases may be supported by D4M, we describe the process of building the D4M-SciDB connector and present performance of this connection.
Static wetting on deformable substrates, from liquids to soft solids

Young's law fails on soft solid and liquid substrates where there are substantial deformations near the contact line. On liquid substrates, this is captured by Neumann's classic analysis, which provides a geometrical construction for minimising the interfacial free energy. On soft solids, the total free energy includes an additional contribution from elasticity. A linear-elastic model incorporating an out-of-plane restoring force due to solid surface tension was recently shown to accurately predict the equilibrium shape of a thin elastic film due to a large sessile droplet. Here, we extend this model to find substrate deformations due to droplets of arbitrary size. While the macroscopic contact angle matches Young's law for large droplets, it matches Neumann's prediction for small droplets. The cross-over droplet size is roughly given by the ratio of the solid's surface tension and elastic modulus. On thin substrates at this cross-over, the macroscopic contact angle increases, indicating that the substrate is effectively less wetting. For droplets of all sizes, the microscopic behaviour near the contact line follows the Neumann construction giving local force balance.
Performance measurements of supercomputing and cloud storage solutions

Increasing amounts of data from varied sources, particularly in the fields of machine learning and graph analytics, are causing storage requirements to grow rapidly. A variety of technologies exist for storing and sharing these data, ranging from parallel file systems used by supercomputers to distributed block storage systems found in clouds. Relatively few comparative measurements exist to inform decisions about which storage systems are best suited for particular tasks. This work provides these measurements for two of the most popular storage technologies: Lustre and Amazon S3. Lustre is an open-source, high performance, parallel file system used by many of the largest supercomputers in the world. Amazon's Simple Storage Service, or S3, is part of the Amazon Web Services offering, and offers a scalable, distributed option to store and retrieve data from anywhere on the Internet. Parallel processing is essential for achieving high performance on modern storage systems. The performance tests used span the gamut of parallel I/O scenarios, ranging from single-client, single-node Amazon S3 and Lustre performance to a large-scale, multi-client test designed to demonstrate the capabilities of a modern storage appliance under heavy load. These results show that, when parallel I/O is used correctly (i.e., many simultaneous read or write processes), full network bandwidth performance is achievable and ranged from 10 gigabits/s over a 10 GigE S3 connection to 0.35 terabits/s using Lustre on a 1200 port 10 GigE switch. These results demonstrate that S3 is well-suited to sharing vast quantities of data over the Internet, while Lustre is well-suited to processing large quantities of data locally.
Scattering mechanisms and spectral properties of the one-dimensional Hubbard model

It is found that the finite-energy spectral properties of the one-dimensional Hubbard model are controlled by the scattering of charged η-spin-zero 2ν-holon composite objects, spin-zero 2ν-spinon composite objects, and charged η-spinless and spinless objects, rather than by the scattering of independent η-spin-1/2 holons and spin-1/2 spinons. Here ν = 1,2,.... The corresponding S matrix is calculated and its relation to the spectral properties is clarified.
A Lower Bound for the First Passage Time Density of the Suprathreshold Ornstein-Uhlenbeck Process

We prove that the rst passage time density (t) for an Ornstein-Uhlenbeck process X(t) obeying dX = X dt + dW to reach a xed threshold from a suprathreshold initial condition x0 > > 0 has a lower bound of the form (t) > k exp pe 6t for positive constants k and p for times t exceeding some positive value u. We obtain explicit expressions for k;p and u in terms of , , x0 and , and discuss application of the results to the synchronization of periodically forced stochastic leaky integrate-and-re model neurons.
Multiversion Concurrency with Bounded Delay and Precise Garbage Collection

In this paper we are interested in bounding the number of instructions taken to process transactions. The main result is a multiversion transactional system that supports constant delay (extra instructions beyond running in isolation) for all read-only transactions, delay equal to the number of processes for writing transactions that are not concurrent with other writers, and lock-freedom for concurrent writers. The system supports precise garbage collection in that versions are identified for collection as soon as the last transaction releases them. As far as we know these are first results that bound delays for multiple readers and even a single writer. The approach is particularly useful in situations where read-transactions dominate write transactions, or where write transactions come in as streams or batches and can be processed by a single writer (possibly in parallel). The approach is based on using functional data structures to support multiple versions, and an efficient solution to the Version Maintenance (VM) problem for acquiring, updating and releasing versions. Our VM algorithm is precise, safe and wait free (PSWF). We experimentally validate our approach by applying it to balanced tree data structure for maintaining ordered maps. We test the transactional system using multiple algorithms for the VM problem, including our PSWF VM algorithm, and implementations with weaker guarantees based on epochs, hazard pointers, and read-copy-update. To evaluate the functional data structure for concurrency and multi-versioning, we implement batched updates for functional tree structures and compare the performance with state-of-the-art concurrent data structures for balanced trees. The experiments indicate our approach works well in practice over a broad set of criteria.
Quantum Hall Effect and Semimetallic Behavior of Dual-Gated ABA-Stacked Trilayer Graphene

The electronic structure of multilayer graphenes depends strongly on the number of layers as well as the stacking order. Here we explore the electronic transport of purely ABA-stacked trilayer graphenes in a dual-gated field-effect device configuration. We find both that the zero-magnetic-field transport and the quantum Hall effect at high magnetic fields are distinctly different from the monolayer and bilayer graphenes, and that they show electron-hole asymmetries that are strongly suggestive of a semimetallic band overlap. When the ABA trilayers are subjected to an electric field perpendicular to the sheet, Landau-level splittings due to a lifting of the valley degeneracy are clearly observed.
Subflexible symplectic manifolds

We introduce a class of Weinstein domains which are sublevel sets of flexible Weinstein manifolds but are not themselves flexible. These manifolds exhibit rather subtle behavior with respect to both holomorphic curve invariants and symplectic flexibility. We construct a large class of examples and prove that every flexible Weinstein manifold can be Weinstein homotoped to have a nonflexible sublevel set.
Undamped nonequilibrium dynamics of a nondegenerate Bose gas in a 3D isotropic trap

We investigate anomalous damping of the monopole mode of a non-degenerate 3D Bose gas under isotropic harmonic confinement as recently reported by the JILA TOP trap experiment (Lobser et al in preparation). Given a realistic confining potential, we develop a model for studying collective modes that includes the effects of anharmonic corrections to a harmonic potential. By studying the influence of these trap anharmonicities throughout a range of temperatures and collisional regimes, we find that the damping is caused by the joint mechanisms of dephasing and collisional relaxation. Furthermore, the model is complimented by Monte Carlo simulations which are in fair agreement with data from the JILA experiment.
Gamma-ray bursts as a threat to life on Earth

Gamma-ray bursts (GRBs) are likely to have made a number of significant impacts on the Earth during the last billion years. The gamma radiation from a burst within a few kiloparsecs would quickly deplete much of the Earth's protective ozone layer, allowing an increase in solar ultraviolet radiation reaching the surface. This radiation is harmful to life, damaging DNA and causing sunburn. In addition, NO2 produced in the atmosphere would cause a decrease in visible sunlight reaching the surface and could cause global cooling. Nitric acid rain could stress portions of the biosphere, but the increased nitrate deposition could be helpful to land plants. We have used a two-dimensional atmospheric model to investigate the effects on the Earth's atmosphere of GRBs delivering a range of fluences, at various latitudes, at the equinoxes and solstices, and at different times of day. We have estimated DNA damage levels caused by increased solar UVB radiation, reduction in solar visible light due to NO2 opacity, and deposition of nitrates through rainout of HNO3. In this paper we give a concise review of this work and discuss current and future work on extending and improving our estimates of the terrestrial impact of a GRB.
Link cobordisms and functoriality in link Floer homology

We construct cobordism maps on link Floer homology associated to decorated link cobordisms. The maps are defined on a curved chain homotopy type invariant. We describe the construction, and prove invariance. We also make a comparison with the graph TQFT for Heegaard Floer homology.
Some surprising implications of background independence in canonical quantum gravity

There is a precise sense in which the requirement of background independence suffices to uniquely select the kinematics of loop quantum gravity (LQG). Specifically, the fundamental kinematic algebra of LQG admits a unique diffeomorphism invariant state. Although this result has been established rigorously, it comes as a surprise to researchers working with other approaches to quantum gravity. The goal of this article is to explain the underlying reasons in a pedagogical fashion using geometrodynamics, keeping the technicalities at their minimum. This discussion will bring out the surprisingly powerful role played by diffeomorphism invariance (and covariance) in non-perturbative, canonical quantum gravity.
Diagrammatic State Sums for 2D Pin-Minus TQFTs

The two dimensional state sum models of Barrett and Tavares are extended to unoriented spacetimes. The input to the construction is an algebraic structure dubbed half twist algebras, a class of examples of which is real separable superalgebras with a continuous parameter. The construction generates pin-minus TQFTs, including the root invertible theory with partition function the Arf-Brown-Kervaire invariant. Decomposability, the stacking law, and Morita invariance of the construction are discussed.
A Numerical Study of Bravyi-Bacon-Shor and Subsystem Hypergraph Product Codes

We provide a numerical investigation of two families of subsystem quantum codes that are related to hypergraph product codes by gauge-fixing. The first family consists of the Bravyi-Bacon-Shor (BBS) codes which have optimal code parameters for subsystem quantum codes local in 2-dimensions. The second family consists of the constant rate “generalized Shor” codes of Bacon and Cassicino [1], which we re-brand as subsystem hypergraph product (SHP) codes. We show that any hypergraph product code can be obtained by entangling the gauge qubits of two SHP codes. To evaluate the performance of these codes, we simulate both small and large examples. For circuit noise, a [21], [4], [3] BBS code and a [49], [16], [3] SHP code have pseudthresholds of 2 × 10−3and 8 × 10−4, respectively. Simulations for phenomenological noise show that large BBS and SHP codes start to outperform surface codes with similar encoding rate at physical error rates 1 × 10−6 and 4 × 10−4, respectively.
In-Home Daily-Life Captioning Using Radio Signals

This paper aims to caption daily life – i.e., to create a textual description of people’s activities and interactions with objects in their homes. Addressing this problem requires novel methods beyond traditional video captioning, as most people would have privacy concerns about deploying cameras throughout their homes. We introduce RF-Diary, a new model for captioning daily life by analyzing the privacy-preserving radio signal in the home with the home’s floormap. RF-Diary can further observe and caption people’s life through walls and occlusions and in dark settings. In designing RF-Diary, we exploit the ability of radio signals to capture people’s 3D dynamics, and use the floormap to help the model learn people’s interactions with objects. We also use a multi-modal feature alignment training scheme that leverages existing video-based captioning datasets to improve the performance of our radio-based captioning model. Extensive experimental results demonstrate that RF-Diary generates accurate captions under visible conditions. It also sustains its good performance in dark or occluded settings, where video-based captioning approaches fail to generate meaningful captions.(For more information, please visit our project webpage: http://rf-diary.csail.mit.edu)
A calibration-free method for biosensing in cell manufacturing

Chimeric antigen receptor T-cell therapy has demonstrated innovative therapeutic effectiveness in fighting cancers; however, it is extremely expensive, due to the intrinsic patient-to-patient varia...
An improved lower bound on multicolor Ramsey numbers

A recent breakthrough of Conlon and Ferber yielded an exponential improvement on the lower bounds for multicolor diagonal Ramsey numbers. In this note, we modify their construction and obtain improved bounds for more than three colors.
Thin film growth effects on electrical conductivity in entropy stabilized oxides

Abstract Entropy stabilization has garnered significant attention as a new approach to designing novel materials. Much of the work in this area has focused on bulk ceramic processing, leaving entropy-stabilized thin films relatively under-explored. Following an extensive multi-variable investigation of polycrystalline (Mg 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 )O thin films deposited via pulsed laser deposition (PLD), it is shown here that substrate temperature and deposition pressure have strong and repeatable effects on film texture and lattice parameter. Further analysis shows that films deposited at lower temperatures and under lower oxygen chamber pressure are ∼ 40 × less electrically resistive than otherwise identical films grown at higher temperature and pressure. Annealing these films in an oxygen-rich environment increases their electrical resistivity to match that of the films grown at higher temperatures and pressures. Because of this, the electric conductivity is hypothesized to be the result of polaron hopping mediated by transition metal valence changes which compensate for oxygen off-stoichiometry.
Resolving multiphoton processes with high-order anisotropy ultrafast X-ray scattering

We present the first results on experimentally measured ultrafast X-ray scattering of strongly driven molecular iodine and analysis of high-order anisotropic components of the scattering signal. We discuss the technical details of retrieving high fidelity high-order anisotropy components from the measured scattering data and outline a method to analyze such signals using Legendre decomposition. We describe how anisotropic motions can be extracted from the various Legendre orders using simulated anisotropic scattering signals and Fourier analysis. We implement the method on the measured signal and observe a multitude of dissociation and vibration motions simultaneously arising from various multiphoton transitions occurring in the sample. We use the anisotropic scattering information to disentangle the different processes and assign their dissociation velocities on the Angstrom and femtosecond scales de novo.