cssi/SciSciGPT-SciSciNet huggingface dataset:
Adaptive Exploration in Linear Contextual Bandit.

Contextual bandits serve as a fundamental model for many sequential decision making tasks. The most popular theoretically justified approaches are based on the optimism principle. While these algorithms can be practical, they are known to be suboptimal asymptotically. On the other hand, existing asymptotically optimal algorithms for this problem do not exploit the linear structure in an optimal way and suffer from lower-order terms that dominate the regret in all practically interesting regimes. We start to bridge the gap by designing an algorithm that is asymptotically optimal and has good finite-time empirical performance. At the same time, we make connections to the recent literature on when exploration-free methods are effective. Indeed, if the distribution of contexts is well behaved, then our algorithm acts mostly greedily and enjoys sub-logarithmic regret. Furthermore, our approach is adaptive in the sense that it automatically detects the nice case. Numerical results demonstrate significant regret reductions by our method relative to several baselines.
Interactions between calmodulin and neurogranin govern the dynamics of CaMKII as a leaky integrator

Calmodulin-dependent kinase II (CaMKII) has long been known to play an important role in learning and memory as well as long term potentiation (LTP). More recently it has been suggested that it might be involved in the time averaging of synaptic signals, which can then lead to the high precision of information stored at a single synapse. However, the role of the scaffolding molecule, neurogranin (Ng), in governing the dynamics of CaMKII is not yet fully understood. In this work, we adopt a rule-based modeling approach through the Monte Carlo method to study the effect of Ca2+ signals on the dynamics of CaMKII phosphorylation in the postsynaptic density (PSD). Calcium surges are observed in synaptic spines during an EPSP and back-propagating action potential due to the opening of NMDA receptors and voltage dependent calcium channels. Using agent-based models, we computationally investigate the dynamics of phosphorylation of CaMKII monomers and dodecameric holoenzymes. The scaffolding molecule, Ng, when present in significant concentration, limits the availability of free calmodulin (CaM), the protein which activates CaMKII in the presence of calcium. We show that Ng plays an important modulatory role in CaMKII phosphorylation following a surge of high calcium concentration. We find a non-intuitive dependence of this effect on CaM concentration that results from the different affinities of CaM for CaMKII depending on the number of calcium ions bound to the former. It has been shown previously that in the absence of phosphatase, CaMKII monomers integrate over Ca2+ signals of certain frequencies through autophosphorylation (Pepke et al, Plos Comp. Bio., 2010). We also study the effect of multiple calcium spikes on CaMKII holoenzyme autophosphorylation, and show that in the presence of phosphatase, CaMKII behaves as a leaky integrator of calcium signals, a result that has been recently observed in vivo. Our models predict that the parameters of this leaky integrator are finely tuned through the interactions of Ng, CaM, CaMKII, and PP1, providing a mechanism to precisely control the sensitivity of synapses to calcium signals. Author Summary not valid for PLOS ONE submissions.
Inducing Human Behavior to Alleviate Overstay at PEV Charging Station

This paper proposes a mathematical framework to optimally operate a plug-in electric vehicle (PEV) charging station, using differentiated charging services. The mathematical framework specifically exploits human behavioral modeling to alleviate "overstay" - when a PEV remains plugged-in after charging service is complete. Discrete Choice Modeling is utilized to capture human decision-making behavior among multiple charging service options that differ in both price and quality-of-service. We reformulate an associated non-convex problem to a multi-convex problem via the Young-Fenchel transform. We then apply Block Coordinate Descent algorithm to efficiently solve the multi-convex problem. Simulation results show a strong potential of the proposed method in realizing benefits in three ways: (i) net profits gains, (ii) overstay reduction, and (iii) increased quality-of-service.
Supersymmetry and Dark Matter

We examine supergravity models with grand unification at Mg possessing R parity invariance. Current data has begun to significantly constrain the parameter space. Thus for mSUGRA, accelerator data places a lower bound on m1/2 of m1/2 ≳ 300 GeV while astronomical data on the amount of relic dark matter narrowly determines mo in terms of m1/2 (for fixed value of tanβ and A 0) due to co-annihilation effects. Additional new data could fix the parameters further. Thus the parameter space is sensitive to the muon magnetic moment anomaly, δa μ , and if δ a μ lies 1 σ above its current central value, it would exclude mSUGRA, while if it lies 1σ below (but is still positive) it pushes the SUSY spectrum into the TeV domain. The B s → μ + μ - decay is seen to be accessible to the Tevatron Runll with branching ratio sensitivity of Br[B s → μ + μ -] > 6.5 x 10-9 with 15fb-1 /detector, and a value of 7(14) x 10-8 obtainable with 2fb-1 would be sufficient to exclude mSUGRA for tan β 40 if δ a μ > 11 x 10-10, and combined measurements of B s → μ + μ -, a μ and m h (or alternately the gluino mass) would effectively determine the mSUGRA parameters for μ > 0. Detector cross sections are then within the range of planned future dark matter experiments. Non-universal models are also discussed, and it is seen that detector cross sections there can be much larger, and can be in the DAMA data region.
Deep whole-genome sequencing of multiple proband tissues and parental blood reveals the complex genetic etiology of congenital diaphragmatic hernias

The diaphragm is critical for respiration and separation of the thoracic and abdominal cavities, and defects in diaphragm development are the cause of congenital diaphragmatic hernias (CDH), a common and often lethal birth defect. The genetic etiology of CDH is complex. Single-nucleotide variants (SNVs), insertions/deletions (indels), and structural variants (SVs) in more than 150 genes have been associated with CDH, although few genes are recurrently mutated in multiple individuals and mutated genes are incompletely penetrant. This suggests that multiple genetic variants in combination, other not-yet-investigated classes of variants, and/or nongenetic factors contribute to CDH etiology. However, no studies have comprehensively investigated in affected individuals the contribution of all possible classes of variants throughout the genome to CDH etiology. In our study, we used a unique cohort of four individuals with isolated CDH with samples from blood, skin, and diaphragm connective tissue and parental blood and deep whole-genome sequencing to assess germline and somatic de novo and inherited SNVs, indels, and SVs. In each individual we found a different mutational landscape that included germline de novo and inherited SNVs and indels in multiple genes. We also found in two individuals a 343 bp deletion interrupting an annotated enhancer of the CDH-associated gene GATA4, and we hypothesize that this common SV (found in 1%-2% of the population) acts as a sensitizing allele for CDH. Overall, our comprehensive reconstruction of the genetic architecture of four CDH individuals demonstrates that the etiology of CDH is heterogeneous and multifactorial.
Amplitude of high frequency oscillations as a biomarker of the seizure onset zone.

Abstract Objective Studies of high frequency oscillations (HFOs) in epilepsy have primarily tested the HFO rate as a biomarker of the seizure onset zone (SOZ), but the rate varies over time and is not robust for all individual subjects. As an alternative, we tested the performance of HFO amplitude as a potential SOZ biomarker using two automated detection algorithms. Method HFOs were detected in intracranial electroencephalogram (iEEG) from 11 patients using a machine learning algorithm and a standard amplitude-based algorithm. For each detector, SOZ and non-SOZ channels were classified using the rate and amplitude of high frequency events, and performance was compared using receiver operating characteristic curves. Results The amplitude of detected events was significantly higher in SOZ. Across subjects, amplitude more accurately classified SOZ/non-SOZ than rate (higher values of area under the ROC curve and sensitivity, and lower false positive rates). Moreover, amplitude was more consistent across segments of data, indicated by lower coefficient of variation. Conclusion As an SOZ biomarker, HFO amplitude offers advantages over HFO rate: it exhibits higher classification accuracy, more consistency over time, and robustness to parameter changes. Significance This biomarker has the potential to increase the generalizability of HFOs and facilitate clinical implementation as a tool for SOZ localization.
Debiased machine learning of conditional average treatment effects and other causal functions

This paper provides estimation and inference methods for the best linear predictor (approximation) of a structural function, such as conditional average structural and treatment effects, and structural derivatives, based on modern machine learning (ML) tools. We represent this structural function as a conditional expectation of an unbiased signal that depends on a nuisance parameter, which we estimate by modern machine learning techniques. We first adjust the signal to make it insensitive (Neyman-orthogonal) with respect to the first-stage regularization bias. We then project the signal onto a set of basis functions, growing with sample size, which gives us the best linear predictor of the structural function. We derive a complete set of results for estimation and simultaneous inference on all parameters of the best linear predictor, conducting inference by Gaussian bootstrap. When the structural function is smooth and the basis is sufficiently rich, our estimation and inference result automatically targets this function. When basis functions are group indicators, the best linear predictor reduces to group average treatment/structural effect, and our inference automatically targets these parameters. We demonstrate our method by estimating uniform confidence bands for the average price elasticity of gasoline demand conditional on income.
Callose deposition is essential for the completion of cytokinesis in the unicellular alga, Penium margaritaceum.

Cytokinesis in land plants involves the formation of a cell plate that develops into the new cell wall. Callose, a β-1,3 glucan accumulates at later stages of cell plate development presumably to stabilize this delicate membrane network during expansion. Cytokinetic callose is considered specific to multicellular plant species, as it has not been detected in unicellular algae. Here we present callose at the cytokinesis junction of the unicellular charophyte, P. margaritaceum. Callose deposition at the division plane of P. margaritaceum showed distinct, spatiotemporal patterns likely representing distinct roles of this polymer in cytokinesis. Pharmacological inhibition by Endosidin 7 resulted in cytokinesis defects, consistent with the essential role for this polymer in P. margaritaceum cell division. Cell wall deposition at the isthmus zone was also affected by the absence of callose, demonstrating the dynamic nature of new wall assembly in P. margaritaceum. The identification of candidate callose synthase genes provides molecular evidence for callose biosynthesis in P. margaritaceum. The evolutionary implications of cytokinetic callose in this unicellular Zygnematopycean alga is discussed in the context of the conquest of land by plants.
Toward the large-eddy simulation of compressible turbulent flows

New subgrid-scale models for the large-eddy simulation of compressible turbulent flows are developed and tested based on the Favre-filtered equations of motion for an ideal gas. A compressible generalization of the linear combination of the Smagorinsky model and scale-similarity model, in terms of Favre-filtered fields, is obtained for the subgrid-scale stress tensor. An analogous thermal linear combination model is also developed for the subgrid-scale heat flux vector. The two dimensionless constants associated with these subgrid-scale models are obtained by correlating with the results of direct numerical simulations of compressible isotropic turbulence performed on a 96 (exp 3) grid using Fourier collocation methods. Extensive comparisons between the direct and modeled subgrid-scale fields are provided in order to validate the models. A large-eddy simulation of the decay of compressible isotropic turbulence (conducted on a coarse 32(exp 3) grid) is shown to yield results that are in excellent agreement with the fine-grid direct simulation. Future applications of these compressible subgrid-scale models to the large-eddy simulation of more complex supersonic flows are discussed briefly.
A National Survey Assessing SARS-CoV-2 Vaccination Intentions: Implications for Future Public Health Communication Efforts

With SARS-CoV-2 vaccines under development, research is needed to assess intention to vaccinate. We conducted a survey (N = 3,159) with U.S. adults in May 2020 assessing SARS-CoV-2 vaccine intentio...
Oxygen Storage in Transition Metal-Doped Bixbyite Vanadium Sesquioxide Nanocrystals

Bixbyite vanadium sesquioxide (V2O3) is a metastable polymorph of vanadium oxide that has been shown to have a significant oxygen storage capacity (OSC) with very low-temperature oxidation onset. I...
Incentivizing Top-Musicians

The high social costs of our copyright law system are traditionally justified as a necessary evil to incentivize the production of more and better information goods. One would, therefore, expect that as copyright becomes stronger, and as the affected industries' revenues increase, productivity will improve. Glynn Lunney’s recent book, Copyright’s Excess: Money and Music in the US Recording Industry, however, shows that, at least when it comes to the recording industry, such a correlation does not exist. This is especially the case with respect to leading musicians, who seem to have reduced their productivity during the industry’s most profitable years. The incentives of top and wealthy artists to continue to create receives relatively little attention in copyright law literature. Those incentives likely do not fit within the overall framework. The formula “money equals incentives” is quite crude with respect to most people, but it seems simply erroneous when it comes to those artists who are already very wealthy. This essay explores the forces that drive superstars’ creativity. It suggests that the main motivations for the creativity of the ultra-wealthy are likely to be rooted in their internal joy from creativity and, possibly even more, in the entailed social-psychological rewards. It concludes by considering some of the possible implications of this incentive structure and with a call for copyright law to focus on the monetary incentives of marginal artists and not those of the ultrarich.
Vector dynamics influence spatially imperfect genetic interventions against disease.

Background and objectives Genetic engineering and similar technologies offer promising new approaches to controlling human diseases by blocking transmission from vectors. However, in spatially structured populations, imperfect coverage of the vector will leave pockets in which the parasite may persist. Movement by humans may disrupt this local persistence and facilitate eradication when these pockets are small, spreading parasite reproduction outside unprotected areas and into areas that block its reproduction. Here, we consider the sensitivity of this process to biological details: do simple generalities emerge that may facilitate interventions? Methodology We develop formal mathematical models of this process similar to standard Ross-Macdonald models, but (i) specifying spatial structure of two patches, with vector transmission blocked in one patch but not in the other, (ii) allowing temporary human movement (travel instead of migration) and (iii) considering two different modes of mosquito biting. Results We find that there is no invariant effect of disrupting spatial structure with travel. For both biting models, travel out of the unprotected patch has different consequences than travel by visitors into the patch, but the effects are reversed between the two biting models. Conclusions and implications Overall, the effect of human travel on the maintenance of vector-borne diseases in structured habitats must be considered in light of the actual biology of mosquito abundances, biting dynamics and human movement patterns. Lay summary: Genetic interventions against pathogens transmitted by insect vectors are promising methods of controlling infectious diseases. These interventions may be imperfect, leaving pockets where the parasite persists. How will human movement between protected and unprotected areas affect persistence? Mathematical models developed here show that the answer is ecology-dependent, depending on vector biting behavior.
A 60-Gb/s PAM4 Wireline Receiver With 2-Tap Direct Decision Feedback Equalization Employing Track-and-Regenerate Slicers in 28-nm CMOS

This article describes a 4-level pulse amplitude modulation (PAM4) receiver incorporating continuous time linear equalizers (CTLEs) and a 2-tap direct decision feedback equalizer (DFE) for applications in wireline communication. A CMOS track-and-regenerate slicer is proposed and employed in the PAM4 receiver. The proposed slicer is designed for the purposes of improving the clock-to-Q delay as well as the output signal swing. A direct DFE in a PAM4 receiver is made possible with the proposed slicer by having rail-to-rail digital feedback signals available with reduced delay, and accordingly relaxing the settling time constraint of the summer. With the 2-tap direct DFE enabled by the proposed slicer, loop-unrolling and inductor-based bandwidth enhancement techniques, which can be area/power intensive, are not necessary at high data rates. The PAM4 receiver fabricated in 28-nm CMOS technology achieves bit-error-rate (BER) better than 1E-12, and energy efficiency of 1.1 pJ/b at 60 Gb/s, measured over a channel with 8.2-dB loss at Nyquist.
Iodoacetic acid disrupts mouse oocyte maturation by inducing oxidative stress and spindle abnormalities.

Abstract Disinfection by-products (DBPs) are compounds produced during the water disinfection process. Iodoacetic acid (IAA) is one of the unregulated DBPs in drinking water, with potent cytotoxicity and genotoxicity in animals. However, whether IAA has toxic effects on oocyte maturation remains unclear. Here, we show that IAA exposure resulted in metaphase I (MI) arrest and polar-body-extrusion failure in mouse oocytes, indicating that IAA had adverse effects on mouse oocyte maturation in vitro. Particularly, IAA treatment caused abnormal spindle assembly and chromosome misalignment. Previous studies reported that IAA is a known inducer of oxidative stress in non-germline cells. Correspondingly, we found that IAA exposure increased the reactive oxygen species (ROS) levels in oocytes in a dose-dependent manner, indicating IAA exposure could induce oxidative stress in oocytes. Simultaneously, DNA damage was also elevated in the nuclei of these IAA-exposed mouse oocytes, evidenced by increased γ-H2AX focus number. In addition, the un-arrested oocytes entered metaphase II (MII) with severe defects in spindle morphologies and chromosome alignment after 14-h IAA treatment. An antioxidant, N-acetyl-L-cysteine (NAC), reduced the elevated ROS level and restored the meiotic maturation in the IAA-exposed oocytes, which indicates that IAA-induced maturation failure in oocytes was mainly mediated by oxidative stress. Collectively, our results indicate that IAA exposure interfered with mouse oocyte maturation by elevating ROS levels, disrupting spindle assembly, inducing DNA damage, and causing MI arrest.
A recrystallization heat-treatment to reduce deformation anisotropy of additively manufactured Inconel 718

Abstract The aim of the current study is to investigate the suitability of a solutionizing recrystallization (RC) heat-treatment to improve the yield strength of laser powder-bed fusion (L-PBF) Inconel 718 (IN718), while decreasing deformation anisotropy under uniaxial compression. Scanning electron microscopy measurements show an increase in grain size, decrease in texture, and the formation of twins in the RC compared to the as-built (AB) and direct-age (DA) hardened conditions. Transmission electron microscopy measurements of the RC condition revealed the formation of nano-precipitates in the gamma matrix. As a result, the compressive stress-strain behavior showed an increase in the yield strength of the RC specimens compared to the AB condition in the quasi-static and high-strain rate regimes despite having significantly larger grain sizes. Post-mortem in-plane ellipticity measurements show a statistically significant decrease in the deformation anisotropy of the RC specimens compared to the AB and DA conditions. Overall, the solutionizing RC heat-treatment, when compared to the AB condition, resulted in an increase in yield strength and decrease in deformation anisotropy, two desirable outcomes necessary to continue to provide path-ways to transitioning L-PBF parts from the research laboratory setting to commercial implementation.
Anomalous dimensions from thermal AdS partition functions

We develop an efficient method for computing thermal partition functions of weakly coupled scalar fields in AdS. We consider quartic contact interactions and show how to evaluate the relevant two-loop vacuum diagrams without performing any explicit AdS integration, the key step being the use of Kallen-Lehmann type identities. This leads to a simple method for extracting double-trace anomalous dimensions in any spacetime dimension, recovering known first-order results in a streamlined fashion.
Unitary Quantum Lattice Simulations for Maxwell Equations in Vacuum and in Dielectric Media

Utilizing the similarity between the spinor representation of the Dirac and the Maxwell equations that has been recognized since the early days of relativistic quantum mechanics, a quantum lattice algorithm (QLA) representation of unitary collision-stream operators of Maxwell's equations is derived for both homogeneous and inhomogeneous media. A second-order accurate 4-spinor scheme is developed and tested successfully for two-dimensional (2-D) propagation of a Gaussian pulse in a uniform medium whereas for normal (1-D) incidence of an electromagnetic Gaussian wave packet onto a dielectric interface requires 8-component spinors because of the coupling between the two electromagnetic polarizations. In particular, the well-known phase change, field amplitudes and profile widths are recovered by the QLA asymptotic profiles without the imposition of electromagnetic boundary conditions at the interface. The QLA simulations yield the time-dependent electromagnetic fields as the wave packet enters and straddles the dielectric boundary. QLA involves unitary interleaved non-commuting collision and streaming operators that can be coded onto a quantum computer: the non-commutation being the very reason why one perturbatively recovers the Maxwell equations.
Perspectives of cancer patients and their health during the COVID-19 pandemic.

Introduction The immunosuppressive nature of some cancers and many cancer-directed treatments may increase the risk of infection with and severe sequelae from Coronavirus Disease 2019 (COVID-19). The objective of this study was to compare concerns about COVID-19 among individuals undergoing cancer treatment to those with a history of cancer not currently receiving therapy and to those without a cancer history. Methods We conducted a cross-sectional anonymous online survey study of adults currently residing in the United States. Participants were recruited over a one-week period (April 3–11, 2020) using promoted advertisements on Facebook and Twitter. Groups were compared using chi-squared tests, Fisher’s exact tests, and t-tests. Results 543 respondents from 47 states provided information on their cancer history and were included in analyses. Participants receiving active treatment reported greater concern about infection from the SARS-CoV-2 coronavirus (p<0.001), higher levels of family distress caused by the COVID-19 pandemic (p = 0.004), and greater concern that the general public does not adequately understand the seriousness of COVID-19 (p = 0.04). Those with metastatic disease were more likely to indicate that COVID-19 had negatively affected their cancer care compared to patients with non-metastatic cancer (50.8% vs. 31.0%; p = 0.02). The most commonly reported treatment modifications included chemotherapy delays. Conclusions Patients undergoing active treatment for cancer were most concerned about the short-term effects of the COVID-19 pandemic on the logistics as well as potential efficacy of ongoing cancer treatment, longer term effects, and overarching societal concerns that the population at large is not as concerned about the public health implications of SARS-CoV-2 infection.
Entanglement and the double copy

We construct entangled states of gluons that scatter exactly as if they were gravitons. Operationally, these objects implement the double copy at the level of the wave function. Our analysis begins with a general ansatz for a wave function characterizing gluons in two copies of SU(N ) gauge theory. Given relatively minimal assumptions following from permutation invariance and dimensional analysis, the three- and four-particle wave functions generate scattering amplitudes that automatically coincide exactly with gravity, modulo normalization. For five-particle scattering the match is not automatic but imposing certain known selection rules on the amplitude is sufficient to uniquely reproduce gravity. The resulting amplitudes exhibit a color-dressed and permutation-invariant form of the usual double copy relations. We compute the entanglement entropy between the two gauge theory copies and learn that these states are maximally-entangled at large N . Moreover, this approach extends immediately to effective field theories, where Born-Infeld photons and Galileons can be similarly recast as entangled gluons and pions.
Lattice thermal transport in group II-alloyed PbTe

PbTe, one of the most promising thermoelectric materials, has recently demonstrated a thermoelectric figure of merit (ZT) of above 2.0 when alloyed with group II elements. The improvements are due mainly to significant reduction of lattice thermal conductivity (κl), which was in turn attributed to nanoparticle precipitates. However, a fundamental understanding of various phonon scattering mechanisms within the bulk alloy is still lacking. In this work, we apply the newly-developed density-functional-theory-based compressive sensing lattice dynamics approach to model lattice heat transport in PbTe, MTe, and Pb0.94M0.06Te (M = Mg, Ca, Sr, and Ba) and compare our results with experimental measurements, with focus on the strain effect and mass disorder scattering. We find that (1) CaTe, SrTe, and BaTe in the rock-salt structure exhibit much higher κl than PbTe, while MgTe in the same structure shows anomalously low κl; (2) lattice heat transport of PbTe is extremely sensitive to static strain induced by alloy...
Evaluating the Calorimeter Model with Broadband, Continuous Spectra of Starburst Galaxies Observed with the Allen Telescope Array

Although the relationship between the far-infrared and centimeter-wave radio luminosities of normal galaxies is one of the most striking correlations in astronomy, a solid understanding of its physical basis is lacking. In one interpretation, the calorimeter model, rapid synchrotron cooling of cosmic ray electrons is essential in reproducing the observed linear relationship. Observed radio spectra, however, are shallower than what is expected of cooled synchrotron emission. In 2006, Thompson et al. presented a simple parameterized model to explain how relatively shallow observed spectra might arise even in the presence of rapid synchrotron cooling by accounting for ionization losses and other cooling mechanisms. During the commissioning of the 42 element Allen Telescope Array (ATA), we observed the starburst galaxies M82, NGC 253, and Arp 220 at frequencies ranging from 1 to 7 GHz, obtaining unprecedented broadband continuous radio spectra of these sources. We combine our observations with high-frequency data from the literature to separate the spectra into thermal and nonthermal components. The nonthermal components all steepen in the centimeter-wave regime and cannot be well modeled as simple power laws. The model of Thompson et al. is consistent with our M82 results when plausible parameters are chosen, and our results in fact significantly shrink the space of allowed model parameters. The model is only marginally consistent with our NGC 253 data. Assuming the Thompson et al. model, a steep electron energy injection index of p = –2.5 is ruled out in M82 and NGC 253 to >99% confidence. We describe in detail the observing procedures, calibration methods, analysis, and consistency checks used for broadband spectral observations with the ATA.
Heterodyne detection of radio-frequency electric fields using point defects in silicon carbide

Sensing electric fields with high sensitivity, high spatial resolution, and at radio frequencies can be challenging to realize. Recently, point defects in silicon carbide have shown their ability to measure local electric fields by optical conversion of their charge state. Here, we report the combination of heterodyne detection with charge-based electric field sensing, solving many of the previous limitations of this technique. Owing to the nonlinear response of the charge conversion to electric fields, the application of a separate “pump” electric field results in a detection sensitivity as low as 1.1 (V/cm)/Hz, with a near-diffraction limited spatial resolution and tunable control of the sensor dynamic range. In addition, we show both incoherent and coherent heterodyne detection, allowing measurements of either unknown random fields or synchronized fields with higher sensitivities. Finally, we demonstrate in-plane vector measurements of the electric field by combining orthogonal pump electric fields. Overall, this work establishes charge-based measurements as highly relevant for solid-state defect sensing.Sensing electric fields with high sensitivity, high spatial resolution, and at radio frequencies can be challenging to realize. Recently, point defects in silicon carbide have shown their ability to measure local electric fields by optical conversion of their charge state. Here, we report the combination of heterodyne detection with charge-based electric field sensing, solving many of the previous limitations of this technique. Owing to the nonlinear response of the charge conversion to electric fields, the application of a separate “pump” electric field results in a detection sensitivity as low as 1.1 (V/cm)/Hz, with a near-diffraction limited spatial resolution and tunable control of the sensor dynamic range. In addition, we show both incoherent and coherent heterodyne detection, allowing measurements of either unknown random fields or synchronized fields with higher sensitivities. Finally, we demonstrate in-plane vector measurements of the electric field by combining orthogonal pump electric fields. O...
Effects of body elasticity on stability of underwater locomotion

We examine the stability of the ‘coast’ motion of fish, that is to say, the motion of a neutrally buoyant fish at constant speed in a straight line. The forces and moments acting on the fish body are thus perfectly balanced. The fish motion is said to be unstable if a perturbation in the conditions surrounding the fish results in forces and moments that tend to increase the perturbation, and it is stable if these emerging forces tend to reduce the perturbation and return the fish to its original state. Stability may be achieved actively or passively. Active stabilization requires neurological control that activates musculo-skeletal components to compensate for the external perturbations acting against stability. Passive stabilization on the other hand requires no energy input by the fish and is dependent upon the fish morphology, i.e. geometry and elastic properties. In this paper, we use a deformable body consisting of an articulated body equipped with torsional springs at its hinge joints and submerged in an unbounded perfect fluid as a simple model to study passive stability as a function of the body geometry and spring stiffness. We show that for given body dimensions, the spring elasticity, when properly chosen, leads to passive stabilization of the (otherwise unstable) coast motion.
SPATIAL VARIATIONS IN GALACTIC H I STRUCTURE ON AU-SCALES TOWARD 3C 147 OBSERVED WITH THE VERY LONG BASELINE ARRAY

This paper reports dual-epoch, Very Long Baseline Array observations of H I absorption toward 3C 147. One of these epochs (2005) represents new observations, while one (1998) represents the reprocessing of previous observations to obtain higher signal-to-noise results. Significant H I opacity and column density variations, both spatially and temporally, are observed with typical variations at the level of Δτ 0.20 and in some cases as large as Δτ 0.70, corresponding to column density fluctuations of order 5 × 1019 cm–2 for an assumed 50 K spin temperature. The typical angular scale is 15 mas; while the distance to the absorbing gas is highly uncertain, the equivalent linear scale is likely to be about 10 AU. Approximately 10% of the face of the source is covered by these opacity variations, probably implying a volume filling factor for the small-scale absorbing gas of no more than about 1%. Comparing our results with earlier results toward 3C 138 (Brogan et al.), we find numerous similarities, and we conclude that small-scale absorbing gas is a ubiquitous phenomenon, albeit with a low probability of intercept on any given line of sight. Further, we compare the volumes sampled by the line of sight through the Galaxy between our two epochs and conclude that, on the basis of the motion of the Sun alone, these two volumes are likely to be substantially different. In order to place more significant constraints on the various models for the origin of these small-scale structures, more frequent sampling is required in any future observations.
Beryllium, Oxygen, and Iron Abundances in Extremely Metal-Deficient Stars

The abundance of beryllium in the oldest, most metal-poor stars acts as a probe of early star formation and Galactic chemical evolution. We have analyzed high-resolution, high signal-to-noise ratio Keck/HIRES spectra of 24 stars with [Fe/H] from –2.3 to –3.5 in order to determine the history of Be abundance and explore the possibility of a Be plateau. We have determined stellar parameters of our sample spectroscopically, using equivalent widths of Fe I, Ti I, and Ti II lines. We have determined O abundances from three OH features which occur in the same spectral region; this region is relatively uncrowded and has a well determined continuum in these very/extremely metal-poor stars. We have supplemented this sample with reanalyzed spectra of 25 stars from previous observations so that our total sample ranges in [Fe/H] from –0.5 to –3.5. Our results indicate that the relationship between Be and [Fe/H] continues to lower metallicities with a slope of 0.92 ± 0.04. Although there is no indication of a plateau with constant Be abundance, the four lowest metallicity stars (below [Fe/H] of –3.0) do show a Be enhancement relative to Fe at the 1σ level. A single relationship between Be and [O/H] has a slope of 1.21 ± 0.08, but there is also a good fit with two slopes: 1.59 above [O/H] = –1.6 and 0.74 for stars with [O/H] below –1.6. This change in slope could result from a change in the dominant production mechanism for Be. In the era of the formation of the more metal-poor stars, Be would be formed by acceleration of CNO atoms in the vicinity of SN II and in later times by high-energy cosmic-rays bombarding CNO in the ambient interstellar gas. We find an excellent correlation between [Fe/H] and [O/H] and show that [O/Fe] is near +1.0 at [Fe/H] = –3.5 declining to 0 at [Fe/H] = 0.
Quantifying Allowable Motion to Achieve Safe Dose Escalation in Pancreatic SBRT

Abstract Purpose Tumor motion plays a key role in the safe delivery of stereotactic body radiation therapy (SBRT) for pancreatic cancer. The purpose of this study was to use tumor motion measured in patients to establish limits on motion magnitude for safe delivery of pancreatic SBRT and to help guide motion-management decisions in potential dose-escalation scenarios. Methods and Materials Using 91 sets of pancreatic tumor motion data, we calculated the motion-convolved dose of the gross tumor volume, duodenum, and stomach for 25 patients with pancreatic cancer. We derived simple linear or quadratic models relating motion to changes in dose and used these models to establish the maximum amount of motion allowable while satisfying error thresholds on key dose metrics. In the same way, we studied the effects of dose escalation and tumor volume on allowable motion. Results In our patient cohort, the mean (range) allowable motion for 33, 40, and 50 Gy to the planning target volume was 11.9 (6.3-22.4), 10.4 (5.2-19.1), and 9.0 (4.2-16.0) mm, respectively. The maximum allowable motion decreased as the dose was escalated and was smaller in patients with larger tumors. We found significant differences in allowable motion between the different plans, suggesting a patient-specific approach to motion management is possible. Conclusions The effects of motion on pancreatic SBRT are highly variable among patients, and there is potential to allow more motion in certain patients, even in dose-escalated scenarios. In our dataset, a conservative limit of 6.3 mm would ensure safe treatment of all patients treated to 33 Gy in 5 fractions.
The Revolution Revolution: Magnetic Morphology Driven Spin-down*

Observations of young open clusters show a bimodal distribution of rotation periods that has been difficult to explain with existing stellar spin-down models. Detailed MHD stellar wind simulations have demonstrated that surface magnetic field morphology has a strong influence on wind-driven angular momentum loss. Observations suggest that faster rotating stars store a larger fraction of their magnetic flux in higher-order multipolar components of the magnetic field. In this work, we present a new model for stellar spin-down that, for the first time, accounts for the stellar surface magnetic field configuration. We show how a magnetic complexity that evolves from complex toward simple configurations as a star spins down can explain the salient features of stellar rotation evolution, including the bimodal distribution of both slow and fast rotators seen in young open clusters.
Emergent SO(3) Symmetry of the Frictionless Shear Jamming Transition

We study the shear jamming of athermal frictionless soft spheres, and find that in the thermodynamic limit, a shear-jammed state exists with different elastic properties from the isotropically-jammed state. For example, shear-jammed states can have a non-zero residual shear stress in the thermodynamic limit that arises from long-range stress-stress correlations. As a result, the ratio of the shear and bulk moduli, which in isotropically-jammed systems vanishes as the jamming transition is approached from above, instead approaches a constant. Despite these striking differences, we argue that in a deeper sense, the shear jamming and isotropic jamming transitions actually have the same symmetry, and that the differences can be fully understood by rotating the six-dimensional basis of the elastic modulus tensor.
Weston-Watkins Hinge Loss and Ordered Partitions

Multiclass extensions of the support vector machine (SVM) have been formulated in a variety of ways. A recent empirical comparison of nine such formulations [Doǧan et al. 2016] recommends the variant proposed by Weston and Watkins (WW), despite the fact that the WW-hinge loss is not calibrated with respect to the 0-1 loss. In this work we introduce a novel discrete loss function for multiclass classification, the ordered partition loss, and prove that the WW-hinge loss is calibrated with respect to this loss. We also argue that the ordered partition loss is maximally informative among discrete losses satisfying this property. Finally, we apply our theory to justify the empirical observation made by Doǧan et al. that the WW-SVM can work well even under massive label noise, a challenging setting for multiclass SVMs.
Towards identification of relevant variables in the observed aerosol optical depth bias between MODIS and AERONET observations

Measurements made by satellite remote sensing, Moderate Resolution Imaging Spectroradiometer (MODIS), and globally distributed Aerosol Robotic Network (AERONET) are compared. Comparison of the two datasets measurements for aerosol optical depth values show that there are biases between the two data products. In this paper, we present a general framework towards identifying relevant set of variables responsible for the observed bias. We present a general framework to identify the possible factors influencing the bias, which might be associated with the measurement conditions such as the solar and sensor zenith angles, the solar and sensor azimuth, scattering angles, and surface reflectivity at the various measured wavelengths, etc. Specifically, we performed analysis for remote sensing Aqua-Land data set, and used machine learning technique, neural network in this case, to perform multivariate regression between the ground-truth and the training data sets. Finally, we used mutual information between the observed and the predicted values as the measure of similarity to identify the most relevant set of variables. The search is brute force method as we have to consider all possible combinations. The computations involves a huge number crunching exercise, and we implemented it by writing a job-parallel program.
Supermassive black holes in the early Universe

The recent discovery of the ultraluminous quasar SDSS J010013.02280225.8 at redshift 6.3 has exacerbated the time compression problem implied by the appearance of supermassive black holes only appr...
Renormalization of gravitational Wilson lines

We continue the study of the Wilson line representation of conformal blocks in two-dimensional conformal field theory; these have an alternative interpretation as gravitational Wilson lines in the context of the AdS3/CFT2 correspondence. The gravitational Wilson line involves a path-ordered exponential of the stress tensor, and its expectation value can be computed perturbatively in an expansion in inverse powers of the central charge c. The short-distance singularities which occur in the associated stress tensor correlators require systematic regularization and renormalization prescriptions, whose consistency with conformal Ward identities presents a subtle problem. The regularization used here combines dimensional regularization and analytic continuation. Representation theoretic arguments, based on SL(2, ℝ) current algebra, predict an exact result for the Wilson line anomalous dimension and, by building on previous work, we verify that the perturbative calculations using our regularization and renormalization prescriptions reproduce the exact result to order 1/c3 included. We also discuss a related, but somewhat simpler, Wilson line in Wess-Zumino-Witten models that yields current algebra conformal blocks, and we emphasize the distinction between Wilson lines constructed out of non-holomorphic and purely holomorphic currents.
Holographic metamagnetism, quantum criticality, and crossover behavior

Using high-precision numerical analysis, we show that 3+1 dimensional gauge theories holographically dual to 4 + 1 dimensional Einstein-Maxwell-Chern-Simons theory undergo a quantum phase transition in the presence of a finite charge density and magnetic field. The quantum critical theory has dynamical scaling exponent z = 3, and is reached by tuning a relevant operator of scaling dimension 2. For magnetic field B above the critical value B c , the system behaves as a Fermi liquid. As the magnetic field approaches B c from the high field side, the specific heat coefficient diverges as 1/(B - B c ), and non-Fermi liquid behavior sets in. For B < B c the entropy density s becomes non-vanishing at zero temperature, and scales according to $$ s \sim \sqrt {{B_c} - B} $$ . At B = B c , and for small non-zero temperature T, a new scaling law sets in for which s ∼ T 1/3. Throughout a small region surrounding the quantum critical point, the ratio s/T 1/3 is given by a universal scaling function which depends only on the ratio (B - B c )/T 2/3. The quantum phase transition involves non-analytic behavior of the specific heat and magnetization but no change of symmetry. Above the critical field, our numerical results are consistent with those predicted by the Hertz/Millis theory applied to metamagnetic quantum phase transitions, which also describe non-analytic changes in magnetization without change of symmetry. Such transitions have been the subject of much experimental investigation recently, especially in the compound Sr3Ru2O7, and we comment on the connections.
On the Linear Independence of Spikes and Sines

The purpose of this work is to survey what is known about the linear independence of spikes and sines. The paper provides new results for the case where the locations of the spikes and the frequencies of the sines are chosen at random. This problem is equivalent to studying the spectral norm of a random submatrix drawn from the discrete Fourier transform matrix. The proof depends on an extrapolation argument of Bourgain and Tzafriri.
Capacity Estimates via Comparison with TRO Channels

A ternary ring of operators (TRO) in finite dimensions is an operator space as an orthogonal sum of rectangular matrices. TROs correspond to quantum channels that are diagonal sums of partial traces, we call TRO channels. TRO channels have simple, single-letter entropy expressions for quantum, private, and classical capacity. Using operator space and interpolation techniques,we perturbatively estimate capacities, capacity regions, and strong converse rates for a wider class of quantum channels by comparison to TRO channels.
Static graph challenge: Subgraph isomorphism

The rise of graph analytic systems has created a need for ways to measure and compare the capabilities of these systems. Graph analytics present unique scalability difficulties. The machine learning, high performance computing, and visual analytics communities have wrestled with these difficulties for decades and developed methodologies for creating challenges to move these communities forward. The proposed Subgraph Isomorphism Graph Challenge draws upon prior challenges from machine learning, high performance computing, and visual analytics to create a graph challenge that is reflective of many real-world graph analytics processing systems. The Subgraph Isomorphism Graph Challenge is a holistic specification with multiple integrated kernels that can be run together or independently. Each kernel is well defined mathematically and can be implemented in any programming environment. Subgraph isomorphism is amenable to both vertex-centric implementations and array-based implementations (e.g., using the Graph-BLAS.org standard). The computations are simple enough that performance predictions can be made based on simple computing hardware models. The surrounding kernels provide the context for each kernel that allows rigorous definition of both the input and the output for each kernel. Furthermore, since the proposed graph challenge is scalable in both problem size and hardware, it can be used to measure and quantitatively compare a wide range of present day and future systems. Serial implementations in C++, Python, Python with Pandas, Matlab, Octave, and Julia have been implemented and their single threaded performance have been measured. Specifications, data, and software are publicly available at GraphChallenge.org.