cssi/SciSciGPT-SciSciNet huggingface dataset:
A Packaged Deal: Effective Support Systems for International Student Spouses

Global student mobility is growing in importance as students increasingly turn their interest worldwide. International student spouses and their personal experiences is an emerging problem of practice in higher education due to their connection to international student retention rates. In particular, what support systems are provided to this demographic is especially important. Interpretive Phenomenological Analysis (IPA) was used to examine international student spouses’ perception of support services at an urban private institution of higher education in the United States. A qualitative approach addressed the following research question: What role do international student spouses perceive institutions of higher education have in terms of offering support services? This study focused on five international student spouses who came to the United States on F2 dependent visa status.
The degree of fine-tuning in our universe — and others

Abstract Both the fundamental constants that describe the laws of physics and the cosmological parameters that determine the properties of our universe must fall within a range of values in order for the cosmos to develop astrophysical structures and ultimately support life. This paper reviews the current constraints on these quantities. The discussion starts with an assessment of the parameters that are allowed to vary. The standard model of particle physics contains both coupling constants ( α , α s , α w ) and particle masses ( m u , m d , m e ) , and the allowed ranges of these parameters are discussed first. We then consider cosmological parameters, including the total energy density of the universe ( Ω ) , the contribution from vacuum energy ( ρ Λ ) , the baryon-to-photon ratio ( η ) , the dark matter contribution ( δ ) , and the amplitude of primordial density fluctuations ( Q ) . These quantities are constrained by the requirements that the universe lives for a sufficiently long time, emerges from the epoch of Big Bang Nucleosynthesis with an acceptable chemical composition, and can successfully produce large scale structures such as galaxies. On smaller scales, stars and planets must be able to form and function. The stars must be sufficiently long-lived, have high enough surface temperatures, and have smaller masses than their host galaxies. The planets must be massive enough to hold onto an atmosphere, yet small enough to remain non-degenerate, and contain enough particles to support a biosphere of sufficient complexity. These requirements place constraints on the gravitational structure constant ( α G ) , the fine structure constant ( α ) , and composite parameters ( C ⋆ ) that specify nuclear reaction rates. We then consider specific instances of possible fine-tuning in stellar nucleosynthesis, including the triple alpha reaction that produces carbon, the case of unstable deuterium, and the possibility of stable diprotons. For all of the issues outlined above, viable universes exist over a range of parameter space, which is delineated herein. Finally, for universes with significantly different parameters, new types of astrophysical processes can generate energy and thereby support habitability.
Metastability of the Nonlinear Wave Equation: Insights from Transition State Theory

This paper is concerned with the longtime dynamics of the nonlinear wave equation in one-space dimension, $$\begin{aligned} u_{tt} - \kappa ^2 u_{xx} +V'(u) =0 \quad x\in [0,1] \end{aligned}$$ where \(\kappa >0\) is a parameter and V(u) is a potential bounded from below and growing at least like \(u^2\) as \(|u|\rightarrow \infty \). Infinite energy solutions of this equation preserve a natural Gibbsian invariant measure, and when the potential is double-welled, for example when \(V(u) = \tfrac{1}{4}(1-u^2)^2\), there is a regime such that two small disjoint sets in the system’s phase-space concentrate most of the mass of this measure. This suggests that the solutions to the nonlinear wave equation can be metastable over these sets, in the sense that they spend long periods of time in these sets and only rarely transition between them. Here, we quantify this phenomenon by calculating exactly via transition state theory (TST) the mean frequency at which the solutions of the nonlinear wave equation with initial conditions drawn from its invariant measure cross a dividing surface lying in between the metastable sets. We also investigate numerically how the mean TST frequency compares to the rate at which a typical solution crosses this dividing surface. These numerical results suggest that the dynamics of the nonlinear wave equation is ergodic and rapidly mixing with respect to the Gibbs invariant measure when the parameter \(\kappa \) in small enough. In this case, successive transitions between the two regions are roughly uncorrelated and their dynamics can be coarse-grained to jumps in a two-state Markov chain whose rate can be deduced from the mean TST frequency. This is a regime in which the dynamics of the nonlinear wave equation displays a metastable behavior that is not fundamentally different from that observed in its stochastic counterpart in which random noise and damping terms are added to the equation. For larger \(\kappa \), however, the dynamics either stops being ergodic, or its mixing time becomes larger than the inverse of the TST frequency, indicating that successive transitions between the metastable sets are correlated and the coarse-graining to a Markov chain fails.
CLASSIFYING CLOSED 2-ORBIFOLDS WITH EULER CHARACTERISTICS

We determine the extent to which the collection of Γ-Euler–Satake characteristics classify closed 2-orbifolds. In particular, we show that the closed, connected, effective, orientable 2-orbifolds are classified by the Γ-Euler–Satake characteristics corresponding to free or free abelian Γ and are not classified by those corresponding to any finite set of finitely generated discrete groups. These results demonstrate that the Γ-Euler–Satake characteristics corresponding to free abelian Γ constitute new invariants of orbifolds. Similarly, we show that such a classification is neither possible for non-orientable 2-orbifolds nor for non-effective 2-orbifolds using any collection of groups Γ.
AdS$_5$ Black Hole Entropy near the BPS Limit

We analyze AdS$_{5}$ black holes that are nearly supersymmetric. They depart from the BPS limit in two distinct ways: a temperature takes them above extremality and a potential maintains extremality but violates a certain constraint. We study the thermodynamics of these deformations and their interplay in detail. We discuss recent microscopic computations of BPS black hole entropy in $ \mathcal{N} $ = 4 SYM and generalize the arguments to the nearBPS regime by relaxing constraints imposed by supersymmetry. Our methods recover gravitational results from microscopic theory also for nearBPS black holes.
Exploring General Gauge Mediation

We explore various aspects of General Gauge Mediation (GGM). We present a reformulation of the correlation functions used in GGM, and further elucidate their IR and UV properties. Additionally we clarify the issue of UV sensitivity in the calculation of the soft masses in the MSSM, highlighting the role of the supertrace over the messenger spectrum. Finally, we present weakly coupled messenger models which fully cover the parameter space of GGM. These examples demonstrate that the full parameter space of GGM is physical and realizable. Thus it should be considered a valid basis for future phenomenological explorations of gauge mediation.
Stability of the positive mass theorem for axisymmetric manifolds

Away from the central axis, we prove the stability of the Positive Mass Theorem in the $W^{1,p}$ sense for asymptotically flat axisymmetric manifolds with nonnegative scalar curvature satisfying some additional technical assumptions. We also derive estimates for the volumes of regions, the areas of axisymmetric surfaces, and the distances between points within the manifolds.
Parallel Quantum Computing Emulation

Quantum computers provide a fundamentally new computing paradigm that promises to revolutionize our ability to solve broad classes of problems. Surprisingly, the basic mathematical structures of gate-based quantum computing, such as unitary operations on a finite-dimensional Hilbert space, are not unique to quantum systems but may be found in certain classical systems as well. Previously, it has been shown that one can represent an arbitrary multi-qubit quantum state in terms of classical analog signals using nested quadrature amplitude modulated signals. Furthermore, using digitally controlled analog electronics one may manipulate these signals to perform quantum gate operations and thereby execute quantum algorithms. The computational capacity of a single signal is, however, limited by the required bandwidth, which scales exponentially with the number of qubits when represented using frequency-based encoding. To overcome this limitation, we introduce a method to extend this approach to multiple parallel signals. Doing so allows a larger quantum state to be emulated with the same gate time required for processing frequency-encoded signals. In the proposed representation, each doubling of the number of signals corresponds to an additional qubit in the spatial domain. Single quit gate operations are similarly extended so as to operate on qubits represented using either frequency-based or spatial encoding schemes. Furthermore, we describe a method to perform gate operations between pairs of qubits represented using frequency or spatial encoding or between frequency-based and spatially encoded qubits. Finally, we describe how this approach may be extended to represent qubits in the time domain as well.
ENTROPY AND CURVATURE VARIATIONS FROM EFFECTIVE POTENTIALS

By using the Jacobi metric of the configuration space, and assuming ergodicity, we calculate the Boltzmann entropy S of a finite-dimensional system around a nondegenerate critical point of its potential energy V. We compare S with the entropy of a quantum or thermal system with effective potential Veff. We examine conditions, up to first order in perturbation theory, under which these entropies are equal.
Topology and Singularities in Cosmological Spacetimes Obeying the Null Energy Condition

We consider globally hyperbolic spacetimes with compact Cauchy surfaces in a setting compatible with the presence of a positive cosmological constant. More specifically, for 3 + 1 dimensional spacetimes which satisfy the null energy condition and contain a future expanding compact Cauchy surface, we establish a precise connection between the topology of the Cauchy surfaces and the occurrence of past singularities. In addition to the Penrose singularity theorem, the proof makes use of some recent advances in the topology of 3-manifolds and of certain fundamental existence results for minimal surfaces.
Theory of parabolic arcs in interstellar scintillation spectra

Interstellar scintillation (ISS), observed as time variation in the intensity of a compact radio source, is caused by small-scale structure in the electron density of the interstellar plasma. Dynamic spectra of ISS show modulation in radio frequency and time. Here we relate the (two-dimensional) power spectrum of the dynamic spectrum—the secondary spectrum—to the scattered image of the source. Recent work has identified remarkable parabolic arcs in secondary spectra. Each point in a secondary spectrum corresponds to interference between points in the scattered image with a certain Doppler shift and a certain delay. The parabolic arc corresponds to the quadratic relation between differential Doppler shift and delay through their common dependence on scattering angle. We show that arcs will occur in all media that scatter significant power at angles larger than the rms angle. Thus, effects such as source diameter, steep spectra, and dissipation scales, which truncate high angle scattering, also truncate arcs. Arcs are equally visible in simulations of nondispersive scattering. They are enhanced by anisotropic scattering when the spatial structure is elongated perpendicular to the velocity. In weak scattering the secondary spectrum is directly mapped from the scattered image, and this mapping can be inverted. We discuss additional observed phenomena including multiple arcs and reverse arclets oriented oppositely to the main arc. These phenomena persist for many refractive scattering times, suggesting that they are due to large-scale density structures, rather than low-frequency components of Kolmogorov turbulence.
Lipschitz minimality of Hopf fibrations and Hopf vector fields

The Hopf fibration S ! S was the first example of a homotopically nontrivial map from a sphere to another sphere of lower dimension, and as such its discovery signaled the birth of homotopy theory. This map and its higher-dimensional cousins S ! CP , S ! HP and S ! S —all of them fibrations of round spheres by great subspheres—are among the most strikingly beautiful maps in geometry and topology. And likewise for the Hopf vector fields on odd-dimensional spheres, that is, the unit vector fields on S tangent to the great circle fibers of S!CP .
The Bull's-Eye Effect: Are Galaxy Walls Observationally Enhanced?

We investigate a distortion in redshift space that causes galaxies to appear to lie in walls concentric about the observer, forming a rough bull's-eye pattern. We simulate what an observer would see in a thin slice of redshift space, including a magnitude limit and constant slice angle. The result is an enhanced ring of galaxies encircling the observer at a distance roughly corresponding to the peak of the selection function. This ring is an artificial enhancement of weak features in real space. This may explain visually prominent features such as the Great Wall and periodicity found in deep narrow fields.
Optimized phase sensing in a truncated SU(1,1) interferometer

Homodyne detection is often used for interferometers based on nonlinear optical gain media. For the configuration of a seeded, “truncated SU(1,1)” interferometer Anderson, et al. [ Phys. Rev. A95, 063843 (2017)] showed how to optimize the homodyne detection scheme and demonstrated theoretically that it can saturate the quantum Cramer-Rao bound for phase estimation. In this work we extend those results by taking into account loss in the truncated SU(1,1) interferometer and determining the optimized homodyne detection scheme for phase measurement. Further, we build a truncated SU(1,1) interferometer and experimentally demonstrate that this optimized scheme achieves a reduction in noise level, corresponding to an enhanced potential phase sensitivity, compared to a typical homodyne detection scheme for a two-mode squeezed state. In doing so, we also demonstrate an improvement in the degree to which we can beat the standard quantum limit with this device.
Diphoton excess at 750 GeV: gluon–gluon fusion or quark–antiquark annihilation?

Recently, ATLAS and CMS collaborations reported an excess in the measurement of diphoton events, which can be explained by a new resonance with a mass around 750 GeV. In this work, we explored the possibility of identifying if the hypothetical new resonance is produced through gluon–gluon fusion or quark–antiquark annihilation, or tagging the beam. Three different observables for beam tagging, namely the rapidity and transverse-momentum distribution of the diphoton, and one tagged bottom-jet cross section, are proposed. Combining the information gained from these observables, a clear distinction of the production mechanism for the diphoton resonance is promising.
A Near-Infrared Spectroscopic Survey of 886 Nearby M Dwarfs

We present a catalog of near-infrared (NIR) spectra and associated measurements for 886 nearby M dwarfs. The spectra were obtained with the NASA-Infrared Telescope Facility SpeX Spectrograph during a two-year observing campaign; they have high signal-to-noise ratios (SNR $>100-150$), span 0.8-2.4 $\mu$m and have $R\sim2000$. Our catalog of measured values contains useful T$_{\mathrm{eff}}$ and composition-sensitive features, empirical stellar parameter measurements, and kinematic, photometric, and astrometric properties compiled from the literature. We focus on measures of M dwarf abundances ([Fe/H] and [M/H]), capitalizing on the precision of recently published empirical NIR spectroscopic calibrations. We explore systematic differences between different abundance calibrations, and to other similar M dwarf catalogs. We confirm that the M dwarf abundances we measure show the expected inverse dependence with kinematic, activity, and color-based age indicators. Finally, we provide updated [Fe/H] and [M/H] for 16 M dwarf planet hosts. This catalog represents the largest published compilation of NIR spectra and associated parameters for M dwarfs. It provides a rich and uniform resource for the nearby M dwarfs, and will be especially valuable for measuring Habitable Zone locations and comparative abundances of the M dwarf planet hosts that will be uncovered by upcoming exoplanet surveys.
Robust scan synchronized force-fluorescence imaging.

Abstract Simultaneous atomic force microscope (AFM) and sample scanning confocal fluorescence microscope measurements are widely used to obtain mechanistic and structural insights into protein dynamics in live cells. However, the absence of a robust technique to synchronously scan both AFM and confocal microscope piezo stages makes it difficult to visualize force-induced changes in fluorescent protein distribution in cells. To address this challenge, we have built an integrated AFM-confocal fluorescence microscope platform that implements a synchronous scanning method which eliminates image artifacts from piezo motion ramping, produces accurate pixel binning and enables the collection of a scanned image of a sample while applying force to a single point on the sample. As proof of principle, we use this instrument to monitor the redistribution of fluorescent E-cadherin, an essential transmembrane protein, in live cells, upon application of mechanical force.
THERMODYNAMICS and CHARGING of INTERSTELLAR IRON NANOPARTICLES

Interstellar iron in the form of metallic iron nanoparticles may constitute a component of the interstellar dust. We compute the stability of iron nanoparticles to sublimation in the interstellar radiation field, finding that iron clusters can persist down to a radius of 4.5 A, and perhaps smaller. We employ laboratory data on small iron clusters to compute the photoelectric yields as a function of grain size and the resulting grain charge distribution in various interstellar environments, finding that iron nanoparticles can acquire negative charges, particularly in regions with high gas temperatures and ionization fractions. If 10% of the interstellar iron is in the form of ultrasmall iron clusters, the photoelectric heating rate from dust may be increased by up to tens of percent relative to dust models with only carbonaceous and silicate grains.
SYSTEM SIZE AND ENERGY DEPENDENCE OF HIGH pT HADRON PRODUCTION MEASURED WITH PHENIX EXPERIMENT AT RHIC

PHENIX has measured high transverse momentum (pT) identified hadrons in different collision species and energies in the last five RHIC runs. The systematic study of the high PT hadron production provides an idea on interaction of hard scattered partons and the matter created in relativistic heavy ion collision. The η/π0 ratio is measured in Au + Au collisions, which gives a hint on the system thermalization and particle production. A future measurement of hadron and photon measurement is discussed.
Fast Jacobian arithmetic for hyperelliptic curves of genus 3

We consider the problem of efficient computation in the Jacobian of a hyperelliptic curve of genus 3 defined over a field whose characteristic is not 2. For curves with a rational Weierstrass point, fast explicit formulas are well known and widely available. Here we address the general case, in which we do not assume the existence of a rational Weierstrass point, using a balanced divisor approach.
Towards Robotic Feeding: Role of Haptics in Fork-Based Food Manipulation

Autonomous feeding is challenging because it requires the manipulation of food items with various compliance, sizes, and shapes. To understand how humans manipulate food items during feeding and to explore ways to adapt their strategies to robots, we collected a rich dataset of human trajectories by asking them to pick up food and feed it to a mannequin. From the analysis of the collected haptic and motion signals, we demonstrate that humans adapt their control policies to accommodate to the compliance and shape of the food item being acquired. We propose taxonomy of manipulation strategies for feeding to highlight such policies. As a first step to generate compliance-dependent policies, we propose a set of classifiers for compliance-based food categorization from haptic and motion signals. We compare these human manipulation strategies with fixed position-control policies via a robot. Our analysis of success and failure cases of human and robot policies further highlights the importance of adapting the policy to the compliance of a food item.
Don’t Parse, Insert: Multilingual Semantic Parsing with Insertion Based Decoding

Semantic parsing is one of the key components of natural language understanding systems. A successful parse transforms an input utterance to an action that is easily understood by the system. Many algorithms have been proposed to solve this problem, from conventional rule-based or statistical slot-filling systems to shift-reduce based neural parsers. For complex parsing tasks, the state-of-the-art method is based on an autoregressive sequence to sequence model that generates the parse directly. This model is slow at inference time, generating parses in O(n) decoding steps (n is the length of the target sequence). In addition, we demonstrate that this method performs poorly in zero-shot cross-lingual transfer learning settings. In this paper, we propose a non-autoregressive parser which is based on the insertion transformer to overcome these two issues. Our approach 1) speeds up decoding by 3x while outperforming the autoregressive model and 2) significantly improves cross-lingual transfer in the low-resource setting by 37% compared to autoregressive baseline. We test our approach on three wellknown monolingual datasets: ATIS, SNIPS and TOP. For cross-lingual semantic parsing, we use the MultiATIS++ and the multilingual TOP datasets.
Stress induces divergent gene expression among lateral habenula efferent pathways.

The lateral habenula (LHb) integrates critical information regarding aversive stimuli that shapes decision making and behavioral responses. The three major LHb outputs innervate dorsal raphe nucleus (DRN), ventral tegmental area (VTA), and the rostromedial tegmental nucleus (RMTg). LHb neurons that project to these targets are segregated and nonoverlapping, and this led us to consider whether they have distinct molecular phenotypes and adaptations to stress exposure. In order to capture a time-locked profile of gene expression after repeated forced swim stress, we used intersectional expression of RiboTag in rat LHb neurons and next-gen RNA sequencing to interrogate the RNAs actively undergoing translation from each of these pathways. The "translatome" in the neurons comprising these pathways was similar at baseline, but diverged after stress, especially in the neurons projecting to the RMTg. Using weighted gene co-expression network analysis, we found one module, which had an overrepresentation of genes associated with phosphoinositide 3 kinase (PI3K) signaling, comprising genes downregulated after stress in the RMTg-projecting LHb neurons. Reduced PI3K signaling in RMTg-projecting LHb neurons may be a compensatory adaptation that alters the functional balance of LHb outputs to GABAergic vs. monoaminergic neurons following repeated stress exposure.
Galactic Contamination in the QMAP Experiment

We quantify the level of foreground contamination in the QMAP cosmic microwave background data with two objectives: (1) to measure the level to which the QMAP power spectrum measurements need to be corrected for foregrounds and (2) to use this data set to further refine current foreground models. We cross-correlate the QMAP data with a variety of foreground templates. The 30 GHz Ka-band data are found to be significantly correlated with the Haslam 408 MHz and Reich & Reich 1420 MHz synchrotron maps but not with the Diffuse Infrared Background Experiment 240, 140, and 100 μm maps or the Wisconsin H-Alpha Mapper survey. The 40 GHz Q band has no significant template correlations. We discuss the constraints that this places on synchrotron, free-free, and dust emission. We also reanalyze the foreground-cleaned Ka-band data and find that the two band power measurements are lowered by 2.3% and 1.3%, respectively.
On the Inference of Thermal Inversions in Hot Jupiter Atmospheres

Several studies in the recent past have inferred the existence of thermal inversions in some transiting hot Jupiter atmospheres. Given the limited data available, the inference of a thermal inversion depends critically on the chemical composition assumed for the atmosphere. In this study, we explore the degeneracies between thermal inversions and molecular abundances in four highly irradiated hot Jupiter atmospheres, dayside observations of which were previously reported to be consistent with thermal inversions based on Spitzer photometry. The four systems are HD 209458b, HAT-P-7b, TrES-4, and TrES-2. We model the exoplanet atmospheres using a one-dimensional line-by-line radiative transfer code with parameterized abundances and temperature structure, and with constraints of energy balance and hydrostatic equilibrium. For each system, we explore the model parameter space with ~106 models using a Markov chain Monte Carlo routine. Our results primarily suggest that a thorough exploration of the model parameter space is necessary to identify thermal inversions in hot Jupiter atmospheres. We find that existing observations of TrES-4 and TrES-2 can both be fit very precisely with models with and without thermal inversions, and with a wide range in chemical composition. On the other hand, observations of HD 209458b and HAT-P-7b are better fit with thermal inversions than without, as has been reported previously. Physically plausible non-inversion models of HD 209458b and HAT-P-7b fit the data only at the 1.7σ observational errors; better fits require substantial enhancement of methane and depletion of CO, which seems implausible in the very hot atmospheres considered here. Second, in the sample under consideration here, we do not see a correlation between irradiation levels and thermal inversions, given current data. Before JWST becomes available, near-IR observations from the ground and with the Hubble Space Telescope, along with existing Spitzer observations, can potentially resolve thermal inversions in some systems. Observations with only two channels of Warm Spitzer photometry and good signal-to-noise ratio can likely identify or rule out thermal inversions if the difference between the fluxes in the 3.6 and 4.5 μm channels is very high.
Electron dynamics in strained graphene

This paper presents a theoretical description of the effects of strain induced by out-of-plane deformations on charge distributions and transport on graphene. A review of a continuum model for elec...
Adjoint methods for static Hamilton–Jacobi equations

We use the adjoint methods to study the static Hamilton–Jacobi equations and to prove the speed of convergence for those equations. The main new ideas are to introduce adjoint equations corresponding to the formal linearizations of regularized equations of vanishing viscosity type, and from the solutions σe of those we can get the properties of the solutions u of the Hamilton–Jacobi equations. We classify the static equations into two types and present two new ways to deal with each type. The methods can be applied to various static problems and point out the new ways to look at those PDE.
Symmetric autocompensating quantum key distribution

We present quantum key distribution schemes which are autocompensating (require no alignment) and symmetric (Alice and Bob receive photons from a central source) for both polarization and time-bin qubits. The primary benefit of the symmetric configuration is that both Alice and Bob may have passive setups (neither Alice nor Bob is required to make active changes for each run of the protocol). We show that both the polarization and the time-bin schemes may be implemented with existing technology. The new schemes are related to previously described schemes by the concept of advanced waves.
A transition-edge sensor-based x-ray spectrometer for the study of highly charged ions at the National Institute of Standards and Technology electron beam ion trap.

We report on the design, commissioning, and initial measurements of a Transition-Edge Sensor (TES) x-ray spectrometer for the Electron Beam Ion Trap (EBIT) at the National Institute of Standards and Technology (NIST). Over the past few decades, the NIST EBIT has produced numerous studies of highly charged ions in diverse fields such as atomic physics, plasma spectroscopy, and laboratory astrophysics. The newly commissioned NIST EBIT TES Spectrometer (NETS) improves the measurement capabilities of the EBIT through a combination of high x-ray collection efficiency and resolving power. NETS utilizes 192 individual TES x-ray microcalorimeters (166/192 yield) to improve upon the collection area by a factor of ∼30 over the 4-pixel neutron transmutation doped germanium-based microcalorimeter spectrometer previously used at the NIST EBIT. The NETS microcalorimeters are optimized for the x-ray energies from roughly 500 eV to 8000 eV and achieve an energy resolution of 3.7 eV–5.0 eV over this range, a more modest (<2×) improvement over the previous microcalorimeters. Beyond this energy range, NETS can operate with various trade-offs, the most significant of which are reduced efficiency at lower energies and being limited to a subset of the pixels at higher energies. As an initial demonstration of the capabilities of NETS, we measured transitions in He-like and H-like O, Ne, and Ar as well as Ni-like W. We detail the energy calibration and data analysis techniques used to transform detector counts into x-ray spectra, a process that will be the basis for analyzing future data.
High-frequency and high-field optically detected magnetic resonance of nitrogen-vacancy centers in diamond

We present the development of an optically detected magnetic resonance (ODMR) system, which enables us to perform the ODMR measurements of a single defect in solids at high frequencies and high magnetic fields. Using the high-frequency and high-field ODMR system, we demonstrate 115 GHz continuous-wave and pulsed ODMR measurements of a single nitrogen-vacancy (NV) center in a diamond crystal at the magnetic field of 4.2 T as well as investigation of field dependence (0–8 T) of the longitudinal relaxation time (T1) of NV centers in nanodiamonds.
AN EXTENDED N=1 FERMIONIC SUPERCURRENT AND ITS ASSOCIATED N=2 SUPERCONFORMAL ALGEBRA

An extended free fermionic construction of the internal N=1 worldsheet supercurrent for four-dimensional superstring theory is given. We show how it can describe theories with massless fermions, and we discuss the corresponding N=2 superconformal algebra. As an intermediate step, we show that an internal N=2 global superconformal invariance occurs in any superstring theory with massless fermions at tree level. To demonstrate this fact, we give the N=2 supercurrents for a model with N=1 spacetime supersymmetry and a model without spacetime supersymmetry.
Computational generation of voids in a-Si and a-Si:H by cavitation at low density

Use of amorphous silicon ($a$-Si) and hydrogenated amorphous silicon ($a$-Si:H) in photovoltaics has been limited by light-induced degradation (the Staebler-Wronski effect) and low hole mobilities, and voids have been implicated in both problems. Accurately modeling the void microstructure is critical to theoretically understanding the cause of these issues. Previous methods of modeling voids have involved removing atoms according to an a priori idea of void structure and/or using computationally expensive molecular dynamics. We propose a new fast and unbiased approach based on the established and efficient Wooten-Winer-Weaire Monte Carlo method, by using a range of fixed densities to generate equilibrium structures of $a$-Si and $a$-Si:H that maintain 4-coordination. We find a smooth evolution in bond lengths, bond angles, and bond angle deviations $\mathrm{\ensuremath{\Delta}}\ensuremath{\theta}$ as the density is changed around the equilibrium value of $4.9\ifmmode\times\else\texttimes\fi{}{10}^{22}$ $\mathrm{atoms}/{\mathrm{cm}}^{3}$. However, a significant change occurs at densities below $4.3\ifmmode\times\else\texttimes\fi{}{10}^{22}$ $\mathrm{atoms}/{\mathrm{cm}}^{3}$, where voids begin to form to relieve tensile stress, akin to a cavitation process in liquids. We find both small voids (radius $\ensuremath{\sim}3$ \AA{}) and larger ones (up to 7 \AA{}), which compare well with available experimental data. The voids have an influence on atomic structure up to 4 \AA{} beyond the void surface and are associated with decreasing structural order, measured by $\mathrm{\ensuremath{\Delta}}\ensuremath{\theta}$. We also observe an increasing medium-range dihedral order with increasing density. Our method allows fast generation of statistical ensembles, resembles a physical process during experimental deposition, and provides a set of void structures for further studies of their effects on degradation, hole mobility, two-level systems, thermal transport, and elastic properties. The basic concept of generating voids at low density is applicable to other amorphous materials.
Snapshot projection optical tomography

We present a plenoptic microscopy configuration for three-dimensional (3D) snapshot imaging, which is dual telecentric and can directly record true projection images corresponding to different viewing angles. It also allows the blocking of high-angle stray rays without sacrificing the light collection efficiency. This configuration, which we call snapshot projection optical tomography (SPOT), arranges an objective lens and a microlens array (MLA) in a $4F$ telecentric configuration (where F denotes the focal length of the lens) and places an aperture stop at the back focal plane of a relay lens. We develop a forward imaging model for SPOT, which can also be applied to existing light-field microscopy techniques using a MLA as a tube lens. Using the developed system, we demonstrate snapshot 3D imaging of various fluorescent beads and a biological cell, which confirms the capability of SPOT for imaging specimens with an extended fluorophore distribution as well as isolated fluorochromes. The transverse and vertical resolutions are measured to be $0.8\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$ and $1.6\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$, respectively.
Jet Substructure at the Large Hadron Collider: A Review of Recent Advances in Theory and Machine Learning

Abstract Jet substructure has emerged to play a central role at the Large Hadron Collider (LHC), where it has provided numerous innovative new ways to search for new physics and to probe the Standard Model in extreme regions of phase space. In this article we provide a comprehensive review of state of the art theoretical and machine learning developments in jet substructure. This article is meant both as a pedagogical introduction, covering the key physical principles underlying the calculation of jet substructure observables, the development of new observables, and cutting edge machine learning techniques for jet substructure, as well as a comprehensive reference for experts. We hope that it will prove a useful introduction to the exciting and rapidly developing field of jet substructure at the LHC.
Analytical Determination of Participation in Superconducting Coplanar Architectures

Superconducting qubits are sensitive to a variety of loss mechanisms, which include dielectric loss from interfaces. The calculation of participation near the key interfaces of planar designs can be accomplished through an analytical description of the electric field density based on conformal mapping. In this way, a 2-D approximation to coplanar waveguide and capacitor designs produces values of the participation as a function of depth from the top metallization layer as well as the volume participation within a given thickness from this surface by reducing the problem to a surface integration over the region of interest. These quantities are compared to finite-element method numerical solutions, which validate the values at large distances from the coplanar metallization but diverge near the edges of the metallization features due to the singular nature of the electric fields. A simple approximation to the electric field energy at shallow depths (relative to the waveguide width) is also presented that closely replicates the numerical results based on conformal mapping and those reported in prior literature. These techniques are applied to the calculation of surface participation within a transmon qubit design, where the effects due to shunting capacitors can be easily integrated with those associated with metallization comprising the local environment of the qubit junction.
D-brane charges and K-homology

It is argued that D-brane charge takes values in K-homology. For smooth manifolds with spin structure, this could explain why the phase factor Ω(x) calculated with a D-brane state x in IIB theory appears in Diaconescu, Moore and Witten's computation of the partition function of IIA string theory.
Beyond the Entropy Power Inequality, via Rearrangements

A lower bound on the Renyi differential entropy of a sum of independent random vectors is demonstrated in terms of rearrangements. For the special case of Boltzmann-Shannon entropy, this lower bound is better than that given by the entropy power inequality. Several applications are discussed, including a new proof of the classical entropy power inequality and an entropy inequality involving symmetrization of Levy processes.
IMPACT PARAMETER SPACE INTERPRETATION FOR GENERALIZED PARTON DISTRIBUTIONS

The Fourier transform of generalized parton distribution functions at ξ = 0 describes the distribution of partons in the transverse plane. The physical significance of these impact parameter dependent parton distribution functions is discussed. In particular, it is shown that they satisfy positivity constraints which justify their physical interpretation as a probability density. The generalized parton distribution H is related to impact parameter distribution of unpolarized quarks for an unpolarized nucleon, $\tilde{H}$ is related to the distribution of longitudinally polarized quarks in a longitudinally polarized nucleon, and E is related to the distortion of the unpolarized quark distribution in the transverse plane when the nucleon has transverse polarization. The magnitude of the resulting transverse flavor dipole moment can be related to the anomalous magnetic moment for that flavor in a model independent way.
Design of an On-Chip Superconducting Microwave Circulator with Octave Bandwidth

Superconducting qubits are a promising platform for quantum computing, but measurements of such circuits rely on the use of ferrite circulators, which are difficult to miniaturize or make lossless. Replacing those circulators with on-chip superconducting ones has become a major research thrust, but so far most of these replacements have been narrow-band. Thus the authors design an on-chip circulator that combines low-loss circulation with instantaneous bandwidth an octave wide. Such a device could enable the multiplexed readout of hundreds of qubits, facilitating the scale-up that is currently a major hurdle in quantum information processing with superconducting circuits.
Galactic S Stars: Investigations of Color, Motion, and Spectral Features

Known bright S stars, recognized as such by their enhanced s-process abundances and C/O ratio, are typically members of the asymptotic giant branch (AGB) or the red giant branch. Few modern digital spectra for these objects have been published, from which intermediate resolution spectral indices and classifications could be derived. For published S stars, we find accurate positions using the Two-Micron All Sky Survey (2MASS), and use the FAST spectrograph of the Tillinghast reflector on Mt. Hopkins to obtain the spectra of 57 objects. We make available a digital S star spectral atlas consisting of 14 spectra of S stars with diverse spectral features. We define and derive basic spectral indices that can help distinguish S stars from late-type (M) giants and carbon stars. We convolve all our spectra with the Sloan Digital Sky Survey bandpasses, and employ the resulting gri magnitudes together with 2MASS JHKs mags to investigate S star colors. These objects have colors similar to carbon and M stars, and are therefore difficult to distinguish by color alone. Using near- and mid-infrared colors from IRAS and Akari, we identify some of the stars as intrinsic (AGB) or extrinsic (with abundances enhanced by past mass transfer). We also use V band and 2MASS magnitudes to calculate a temperature index for stars in the sample. We analyze the proper motions and parallaxes of our sample stars to determine upper and lower limit absolute magnitudes and distances, and confirm that most are probably giants.
Green-Kubo Formulas with Symmetrized Correlation Functions for Quantum Systems in Steady States: The Shear Viscosity of a Fluid in a Steady Shear Flow

For a quantum system in a steady state with a constant current of heat or particles driven by a temperature or chemical potential difference between two reservoirs attached to the system, the fluctuation theorem for the current was previously shown to lead to the Green-Kubo formula for the linear response coefficient for the current expressed in terms of the symmetrized correlation function of the current density operator. In this article, we show that for a quantum system in a steady state with a constant rate of work done on the system, the fluctuation theorem for a quantity induced in the system also leads to the Green-Kubo formula expressed in terms of the symmetrized correlation function of the induced quantity. As an example, we consider a fluid in a steady shear flow driven by a constant velocity of a solid plate moving above the fluid.
Atmospheric Circulations of Hot Jupiters as Planetary Heat Engines

James McDonnell Foundation postdoctoral fellowship; NASA Earth and Space Science fellowship; Heising-Simons Foundation
Baryogenesis at a lepton-number-breaking phase transition

We study a scenario in which the baryon asymmetry of the universe arises from a cosmological phase transition where lepton-number is spontaneously broken. If the phase transition is first order, a lepton-number asymmetry can arise at the bubble wall, through dynamics similar to electroweak baryogenesis, but involving right-handed neutrinos. In addition to the usual neutrinoless double beta decay in nuclear experiments, the model may be probed through a variety of “baryogenesis by-products”, which include a stochastic background of gravitational waves created by the colliding bubbles. Depending on the model, other aspects may include a network of topological defects that produce their own gravitational waves, additional contribution to dark radiation, and a light pseudo-Goldstone boson (majoron) as dark matter candidate.
Competition between the electronic and phonon–mediated scattering channels in the out–of–equilibrium carrier dynamics of semiconductors: an ab-initio approach

The carrier dynamics in bulk Silicon, a paradigmatic indirect gap semiconductor, is studied by using the Baym–Kadanoff equations. Both the electron–electron (e–e) and electron–phonon (e–p) self-energies are calculated fully ab–initio by using a semi–static out–of– equilibrium GW approximation in the e–e case and a Fan self–energy in the e-p case. By using the generalized Baym–Kadanoff ansatz the two–time evolution is replaced by the only dynamics on the macroscopic time axis. The enormous numerical difficulties connected with a real–time simulation of realistic systems is overcome by using a completed collision approximation that further simplifies the memory effects connected to the time evolution. The carrier dynamics is shown to reduce in such a way to have stringent connections to the well–known equilibrium electron–electron and electron–phonon self–energies. This link allows to use general arguments to motivate the relative balance between the e–e and e–p scattering channels on the basis of the carrier energies.
OVERSTABLE LIBRATIONS CAN ACCOUNT FOR THE PAUCITY OF MEAN MOTION RESONANCES AMONG EXOPLANET PAIRS

We assess the multi-planet systems discovered by the Kepler satellite in terms of current ideas about orbital migration and eccentricity damping due to planet-disk interactions. Our primary focus is on first order mean motion resonances, which we investigate analytically to lowest order in eccentricity. Only a few percent of planet pairs are in close proximity to a resonance. However, predicted migration rates (parameterized by ) imply that during convergent migration most planets would have been captured into first order resonances. Eccentricity damping (parameterized by ) offers a plausible resolution. Estimates suggest ? e /? n ~ (h/a)2 ~ 10?2, where h/a is the ratio of disk thickness to radius. Together, eccentricity damping and orbital migration give rise to an equilibrium eccentricity, e eq ~ (? e /? n )1/2. Capture is permanent provided e eq ?1/3, where ? denotes the planet to star mass ratio. But for e eq ?1/3, capture is only temporary because librations around equilibrium are overstable and lead to passage through resonance on timescale ? e . Most Kepler planet pairs have e eq > ?1/3. Since ? n ? e is the timescale for migration between neighboring resonances, only a modest percentage of pairs end up trapped in resonances after the disk disappears. Thus the paucity of resonances among Kepler pairs should not be taken as evidence for in situ planet formation or the disruptive effects of disk turbulence. Planet pairs close to a mean motion resonance typically exhibit period ratios 1%-2% larger than those for exact resonance. The direction of this shift undoubtedly reflects the same asymmetry that requires convergent migration for resonance capture. Permanent resonance capture at these separations from exact resonance would demand ?(? n /? e )1/2 0.01, a value that estimates of ? from transit data and (? e /? n )1/2 from theory are insufficient to match. Plausible alternatives involve eccentricity damping during or after disk dispersal. The overstability referred to above has applications beyond those considered in this investigation. It was discovered numerically by Meyer & Wisdom in their study of the tidal evolution of Saturn's satellites.