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Results for "A. W. Case"

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Observations of Gamma-Ray Outbursts from Galactic MicroquasarsSep 13 2004Oct 05 2004The BATSE earth-occultation database provides nine years of coverage for 75 $\gamma$-ray sources in the energy range 35-1700 keV. For transient sources, this long time-base dataset makes it possible to study the repeated outbursts from individual objects. ... More
A zone of preferential ion heating extends tens of solar radii from SunAug 18 2017The extreme temperatures and non-thermal nature of the solar corona and solar wind arise from an unidentified physical mechanism that preferentially heats certain ion species relative to others. Spectroscopic indicators of unequal temperatures commence ... More
Bounded Turing Reductions and Data Processing Inequalities for SequencesAug 16 2016A data processing inequality states that the quantity of shared information between two entities (e.g. signals, strings) cannot be significantly increased when one of the entities is processed by certain kinds of transformations. In this paper, we prove ... More
Measurements of Compton Scattered Transition Radiation at High Lorentz FactorsSep 17 2002Feb 05 2004X-ray transition radiation can be used to measure the Lorentz factor of relativistic particles. Standard transition radiation detectors (TRDs) typically incorporate thin plastic foil radiators and gas-filled x-ray detectors, and are sensitive up to \gamma ... More
Initial Results of New Tomographic Imaging of the Gamma-Ray Sky with BATSEDec 21 2009We describe an improved method of mapping the gamma-ray sky by applying the Linear Radon Transform to data from BATSE on NASA's CGRO. Based on a method similar to that used in medical imaging, we use the relatively sharp (~0.25 deg) limb of the Earth ... More
[Plasma 2020 Decadal] Multipoint Measurements of the Solar Wind: A Proposed Advance for Studying Magnetized TurbulenceMar 13 2019A multi-institutional, multi-national science team will soon submit a NASA proposal to build a constellation of spacecraft to fly into the near-Earth solar wind in a swarm spanning a multitude of scales in order to obtain critically needed measurements ... More
Sharp weighted Sobolev trace inequalities and fractional powers of the LaplacianJan 28 2019We establish a family of sharp Sobolev trace inequalities involving the $W^{k,2}(\mathbb{R}_+^{n+1},y^a)$-norm. These inequalities are closely related to the realization of fractional powers of the Laplacian on $\mathbb{R}^n=\partial\mathbb{R}_+^{n+1}$ ... More
The energy of a smooth metric measure space and applicationsNov 11 2010May 03 2012We introduce and study the notion of the energy of a smooth metric measure space, which includes as special cases the Yamabe constant and Perelman's $\nu$-entropy. We then investigate some properties the energy shares with these constants, in particular ... More
On the nonexistence of quasi-Einstein metricsFeb 12 2009Feb 04 2010We study complete Riemannian manifolds satisfying the equation $Ric+\nabla^2 f-\frac{1}{m}df\otimes df=0$ by studying the associated PDE $\Delta_f f + m\mu e^{2f/m}=0$ for $\mu\leq 0$. By developing a gradient estimate for $f$, we show there are no nonconstant ... More
Smooth metric measure spaces and quasi-Einstein metricsNov 11 2010May 03 2012Smooth metric measure spaces have been studied from the two different perspectives of Bakry-\'Emery and Chang-Gursky-Yang, both of which are closely related to work of Perelman on the Ricci flow. These perspectives include a generalization of the Ricci ... More
A notion of the weighted $σ_k$-curvature for manifolds with densitySep 15 2014Apr 01 2016We propose a natural definition of the weighted $\sigma_k$-curvature for a manifold with density; i.e.\ a triple $(M^n,g,e^{-\phi}\mathrm{dvol})$. This definition is intended to capture the key properties of the $\sigma_k$-curvatures in conformal geometry ... More
Non-Obfuscated Unprovable Programs & Many Resultant SubtletiesMar 30 2016Apr 19 2016The \emph{International Obfuscated C Code Contest} was a programming contest for the most creatively obfuscated yet succinct C code. By \emph{contrast}, an interest herein is in programs which are, \emph{in a sense}, \emph{easily} seen to be correct, ... More
The weighted $σ_k$-curvature of a smooth metric measure spaceAug 04 2016We propose a definition of the weighted $\sigma_k$-curvature of a smooth metric measure space and justify it in two ways. First, we show that the weighted $\sigma_k$-curvature prescription problem is governed by a fully nonlinear second order elliptic ... More
Translation of Einstein's Attempt of a Unified Field Theory with TeleparallelismMar 06 2005We present the first English translation of Einstein's original papers related to the teleparallel ('absolute parallelism', 'distant parallelism' and the German 'Fernparallelismus' are synonyms) attempt of an unified field theory of gravitation and electromagnetism. ... More
Singularity theorems and the Lorentzian splitting theorem for the Bakry-Emery-Ricci tensorDec 09 2007Jun 03 2008We consider the Hawking-Penrose singularity theorems and the Lorentzian splitting theorem under the weaker curvature condition of nonnegative Bakry-Emery-Ricci curvature $Ric_f^m$ in timelike directions. We prove that they still hold when $m$ is finite, ... More
Coalescence of Low-Viscosity Fluids in AirSep 09 2008An electrical method is used to study the early stages of coalescence of two low-viscosity drops. A drop of aqueous NaCl solution is suspended in air above a second drop of the same solution which is grown until the drops touch. At that point a rapidly ... More
A weighted renormalized curvature for manifolds with densityMar 09 2016We introduce a scalar invariant on manifolds with density which is analogous to the renormalized volume coefficient $v_3$ in conformal geometry. We show that this invariant is variational and that shrinking gradient Ricci solitons are stable with respect ... More
Some energy inequalities involving fractional GJMS operatorsSep 28 2015Aug 23 2016Under a spectral assumption on the Laplacian of a Poincar\'e--Einstein manifold, we establish an energy inequality relating the energy of a fractional GJMS operator of order $2\gamma\in(0,2)$ or $2\gamma\in(2,4)$ and the energy of the weighted conformal ... More
Boundary operators associated to the Paneitz operatorSep 28 2015We describe a set of conformally covariant boundary operators associated to the Paneitz operator, in the sense that they give rise to a conformally covariant energy functional for the Paneitz operator on a compact Riemannian manifold with boundary. These ... More
Suppression of the near-infrared OH night sky lines with fibre Bragg gratings - first resultsJun 28 2012The background noise between 1 and 1.8 microns in ground-based instruments is dominated by atmospheric emission from hydroxyl molecules. We have built and commissioned a new instrument, GNOSIS, which suppresses 103 OH doublets between 1.47 - 1.7 microns ... More
A Precision Measurement of Nuclear Muon Capture on 3HeAug 29 1997The muon capture rate in the reaction mu- 3He -> nu + 3H has been measured at PSI using a modular high pressure ionization chamber. The rate corresponding to statistical hyperfine population of the mu-3He atom is (1496.0 +- 4.0) s^-1. This result confirms ... More
Renormalization group approach to 2D Coulomb interacting Dirac fermions with random gauge potentialOct 15 2007We argue that massless Dirac particles in two spatial dimensions with $1/r$ Coulomb repulsion and quenched random gauge field are described by a manifold of fixed points which can be accessed perturbatively in disorder and interaction strength, thereby ... More
A fully nonlinear Sobolev trace inequalityMay 31 2016The $k$-Hessian operator $\sigma_k$ is the $k$-th elementary symmetric function of the eigenvalues of the Hessian. It is known that the $k$-Hessian equation $\sigma_k(D^2u)=f$ with Dirichlet boundary condition $u=0$ is variational; indeed, this problem ... More
Quantum Critical Behavior of the Cluster Glass PhaseDec 06 2006Oct 22 2007In disordered itinerant magnets with arbitrary symmetry of the order parameter, the conventional quantum critical point between the ordered phase and the paramagnetic Fermi-liquid (PMFL) is destroyed due to the formation of an intervening cluster glass ... More
Mutual DimensionOct 15 2014We define the lower and upper mutual dimensions $mdim(x:y)$ and $Mdim(x:y)$ between any two points $x$ and $y$ in Euclidean space. Intuitively these are the lower and upper densities of the algorithmic information shared by $x$ and $y$. We show that these ... More
Mutual Dimension and Random SequencesMar 30 2016If $S$ and $T$ are infinite sequences over a finite alphabet, then the lower and upper mutual dimensions $mdim(S:T)$ and $Mdim(S:T)$ are the upper and lower densities of the algorithmic information that is shared by $S$ and $T$. In this paper we investigate ... More
Fluctuation-induced first order transition due to Griffiths anomalies of the Cluster glass phaseJul 04 2007In itinerant magnetic systems with disorder, the quantum Griffiths phase at T=0 is unstable to formation of a cluster glass (CG) of frozen droplet degrees of freedom. In the absence of the fluctuations associated with these degrees of freedom, the transition ... More
A New $Σ-D$ Relation and Its Application to the Galactic Supernova Remnant DistributionJul 15 1998Technological advances in radio telescopes and X-ray instruments over the last 20 years have greatly increased the number of known supernova remnants (SNRs) and led to a better determination of their properties. In particular, more SNRs now have reasonably ... More
A Paneitz-type operator for CR pluriharmonic functionsSep 10 2013We introduce a fourth order CR invariant operator on pluriharmonic functions on a three-dimensional CR manifold, generalizing to the abstract setting the operator discovered by Branson, Fontana and Morpurgo. For a distinguished class of contact forms, ... More
A generalization of the Cai--Galloway splitting theorem to smooth metric measure spacesJul 02 2013We generalize the splitting theorem of Cai-Galloway for complete Riemannian manifolds with $\Ric\geq-(n-1)$ admitting a family of compact hypersurfaces tending to infinity with mean curvatures tending to $n-1$ sufficiently fast to the setting of smooth ... More
Earth Occultation Imaging of the Low Energy Gamma-Ray Sky with GBMApr 04 2013Jan 22 2014The Earth Occultation Technique (EOT) has been applied to Fermi's Gamma-ray Burst Monitor (GBM) to perform all-sky monitoring for a predetermined catalog of hard X-ray/soft gamma-ray sources. In order to search for sources not in the catalog, thus completing ... More
Searching for Unmodeled Sources Using the Earth Occultation Data from the Fermi GBMNov 01 2011Employing the 12 NaI detectors in the Fermi GBM, the Earth Occultation Technique (EOT) can be used to measure the fluxes of x-ray and gamma-ray sources. Each time a source passes behind the Earth (or emerges from behind the Earth), a step-like feature ... More
GBM Monitoring of Cyg X-1 During the Recent State TransitionNov 02 2011Cygnus X-1 is a high-mass x-ray binary with a black hole compact object. It is normally extremely bright in hard x-rays and low energy gamma rays and resides in the canonical hard spectral state. Recently, however, Cyg X-1 made a transition to the canonical ... More
Precise Measurement of Muon Capture on the ProtonFeb 12 2002The aim of the MuCap experiment is a 1% measurement of the singlet capture rate Lambda_S for the basic electro-weak reaction mu + p -> n + nu_mu. This observable is sensitive to the weak form-factors of the nucleon, in particular to the induced pseudoscalar ... More
Measurement of the Formation Rate of Muonic Hydrogen MoleculesFeb 03 2015Background: The rate \lambda_pp\mu\ characterizes the formation of pp\mu\ molecules in collisions of muonic p\mu\ atoms with hydrogen. In measurements of the basic weak muon capture reaction on the proton to determine the pseudoscalar coupling g_P, capture ... More
Measurement of the Rate of Muon Capture in Hydrogen Gas and Determination of the Proton's Pseudoscalar Coupling $g_P$Apr 16 2007The rate of nuclear muon capture by the proton has been measured using a new experimental technique based on a time projection chamber operating in ultra-clean, deuterium-depleted hydrogen gas at 1 MPa pressure. The capture rate was obtained from the ... More
Search for a 33.9 MeV/c^2 Neutral Particle in Pion DecayDec 24 1999The E815 (NuTeV) neutrino experiment has performed a search for a 33.9 MeV/c^2 weakly-interacting neutral particle produced in pion decay. Such a particle may be responsible for an anomaly in the timing distribution of neutrino interactions in the KARMEN ... More
Measurement of Muon Capture on the Proton to 1% Precision and Determination of the Pseudoscalar Coupling g_POct 24 2012Jan 29 2013The MuCap experiment at the Paul Scherrer Institute has measured the rate L_S of muon capture from the singlet state of the muonic hydrogen atom to a precision of 1%. A muon beam was stopped in a time projection chamber filled with 10-bar, ultra-pure ... More
Coalescence in low-viscosity liquidsSep 10 2007The expected universal dynamics associated with the initial stage of droplet coalescence are difficult to study visually due to the rapid motion of the liquid and the awkward viewing geometry. Here we employ an electrical method to study the coalescence ... More
A Remark on the Kernel of the CR Paneitz operatorFeb 06 2015For CR structures in dimension three, the CR pluriharmonic functions are characterized by the vanishing of a third order operator. This third order operator, after composition with the divergence operator, gives the fourth order analogue of the Paneitz ... More
On fractional GJMS operatorsJun 07 2014Dec 19 2014We describe a new interpretation of the fractional GJMS operators as generalized Dirichlet-to-Neumann operators associated to weighted GJMS operators on naturally associated smooth metric measure spaces. This gives a geometric interpretation of the Caffarelli--Silvestre ... More
Housing risk and return: Evidence from a housing asset-pricing modelMar 30 2011This paper investigates the risk-return relationship in determination of housing asset pricing. In so doing, the paper evaluates behavioral hypotheses advanced by Case and Shiller (1988, 2002, 2009) in studies of boom and post-boom housing markets. The ... More
On how percolation threshold affects PSO performanceApr 17 2012Statistical evidence of the influence of neighborhood topology on the performance of particle swarm optimization (PSO) algorithms has been shown in many works. However, little has been done about the implications could have the percolation threshold in ... More
Community structure in real-world networks from a non-parametrical synchronization-based dynamical approachJul 12 2012This work analyzes the problem of community structure in real-world networks based on the synchronization of nonidentical coupled chaotic R\"{o}ssler oscillators each one characterized by a defined natural frequency, and coupled according to a predefined ... More
Rigidity of Quasi-Einstein MetricsMay 20 2008We call a metric quasi-Einstein if the $m$-Bakry-Emery Ricci tensor is a constant multiple of the metric tensor. This is a generalization of Einstein metrics, which contains gradient Ricci solitons and is also closely related to the construction of the ... More
The CR Paneitz Operator and the Stability of CR Pluriharmonic FunctionsFeb 06 2015Oct 06 2015We give a condition which ensures that the Paneitz operator of an embedded three-dimensional CR manifold is nonnegative and has kernel consisting only of the CR pluriharmonic functions. Our condition requires uniform positivity of the Webster scalar curvature ... More
Compton Scattered Transition Radiation from Very High Energy ParticlesJun 04 2002X-ray transition radiation can be used to measure the Lorentz factor of relativistic particles. At energies approaching gamma = E/mc^2 = 10^5, transition radiation detectors (TRDs) can be optimized by using thick (sim 5 - 10 mil) foils with large (5-10 ... More
Screening in anisotropic superfluids and the superfluid density in underdoped cupratesApr 11 2005Jul 06 2005We examine the nature of the collective excitations in a strongly anisotropic system of bosons interacting via Coulomb interaction. Such a system has often been used in the past to model the effects of quantum and classical phase fluctuations on the superfluid ... More
Spout States in the Selective Withdrawal SystemAug 07 2006Aug 07 2006In selective withdrawal, fluid is withdrawn through a nozzle suspended above the flat interface separating two immiscible, density-separated fluids of viscosities $\nu_{upper}$ and $\nu_{lower} = \lambda \nu_{upper}$. At low withdrawal rates, the interface ... More
Sensitivity to the KARMEN Timing Anomaly at MiniBooNEAug 02 2001We present sensitivities for the MiniBooNE experiment to a rare exotic pion decay producing a massive particle, Q^0. This type of decay represents one possible explanation for the timing anomaly reported by the KARMEN collaboration. MiniBooNE will be ... More
On the Effective Use of Pretraining for Natural Language InferenceOct 05 2017Neural networks have excelled at many NLP tasks, but there remain open questions about the performance of pretrained distributed word representations and their interaction with weight initialization and other hyperparameters. We address these questions ... More
Finite temperature superfluid density in very underdoped cupratesJan 08 2004Aug 10 2004The combination of a large superconducting gap, low transition temperature, and quasi two-dimensionality in strongly underdoped high temperature superconductors severely constrains the behavior of the ab-plane superfluid density \rho with temperature ... More
Large-N theory of strongly commensurate dirty-bosons: absence of transition in two dimensionsMay 22 2001Sep 14 2001The spherical limit of strongly commensurate dirty-bosons is studied perturbatively at weak disorder and numerically at strong disorder in two dimensions (2D). We argue that disorder is not perfectly screened by interactions, and consequently that the ... More
X-Ray and Optical Observations of A 0535+26Sep 19 2011Oct 16 2012We present recent contemporaneous X-ray and optical observations of the Be/X-ray binary system A\,0535+26 with the \textit{Fermi}/Gamma-ray Burst Monitor (GBM) and several ground-based observatories. These new observations are put into the context of ... More
Laboratory plasma physics experiments using merging supersonic plasma jetsAug 01 2014Apr 21 2015We describe a laboratory plasma physics experiment at Los Alamos National Laboratory that uses two merging supersonic plasma jets formed and launched by pulsed-power-driven rail guns. The jets can be formed using any atomic species or mixture available ... More
All-Sky Earth Occultation Observations with the Fermi Gamma Ray Burst MonitorDec 18 2009Using the Gamma Ray Burst Monitor (GBM) on-board Fermi, we are monitoring the hard X-ray/soft gamma ray sky using the Earth occultation technique. Each time a source in our catalog enters or exits occultation by the Earth, we measure its flux using the ... More
Observations of Soft Gamma Ray Sources >100 keV Using Earth Occultation with GBMJan 06 2010Jan 06 2010The NaI and BGO detectors on the Gamma ray Burst Monitor (GBM) on Fermi are now being used for long term monitoring of the hard X-ray/low energy gamma ray sky. Using the Earth occultation technique demonstrated previously by the BATSE instrument on the ... More
Near-threshold production of the multi-strange $Ξ^-$ hyperonFeb 18 2003Jul 26 2003The yield for the multi-strange $\Xi^{-}$ hyperon has been measured in 6 AGeV Au+Au collisions via reconstruction of its decay products $\pi^{-}$ and $\Lambda$, the latter also being reconstructed from its daughter tracks of $\pi^{-}$ and p. The measurement ... More
Laying the groundwork at the AGS: Recent results from experiment E895Apr 11 2001The E895 Collaboration at the Brookhaven AGS has performed a systematic investigation of Au+Au collisions at 2-8 AGeV, using a large-acceptance Time Projection Chamber. In addition to extensive measurements of particle flow, spectra, two-particle interferometry, ... More
Longitudinal Flow of Protons from 2-8 AGeV Central Au+Au CollisionsNov 09 2001Mar 07 2002Rapidity distributions of protons from central $^{197}$Au + $^{197}$Au collisions measured by the E895 Collaboration in the energy range from 2 to 8 AGeV at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including ... More
Azimuthal Dependence of Pion Interferometry at the AGSJul 29 2000Dec 05 2000Two-pion correlation functions, measured as a function of azimuthal emission angle with respect to the reaction plane, provide novel information on the anisotropic shape and orientation of the pion-emitting zone formed in heavy ion collisions. We present ... More
Comparison of Source Images for protons, $π^-$'s and $Λ$'s in 6 AGeV Au+Au collisionsDec 28 2002Jul 16 2003Source images are extracted from two-particle correlations constructed from strange and non-strange hadrons produced in 6 AGeV Au + Au collisions. Very different source images result from pp vs p$\Lambda$ vs $\pi^-\pi^-$ correlations. These observations ... More
Sideward Flow in Au + Au Collisions Between 2A GeV and 8A GeVMay 15 2000May 24 2000Using the large acceptance Time Projection Chamber of experiment E895 at Brookhaven, measurements of collective sideward flow in Au + Au collisions at beam energies of 2, 4, 6 and 8A GeV are presented in the form of in-plane transverse momentum <Px> and ... More
Extremal metrics for the ${Q}^\prime$-curvature in three dimensionsNov 17 2015Feb 09 2016We construct contact forms with constant $Q^\prime$-curvature on compact three-dimensional CR manifolds which admit a pseudo-Einstein contact form and satisfy some natural positivity conditions. These contact forms are obtained by minimizing the CR analogue ... More
Stress-Testing Neural Models of Natural Language Inference with Multiply-Quantified SentencesOct 30 2018Standard evaluations of deep learning models for semantics using naturalistic corpora are limited in what they can tell us about the fidelity of the learned representations, because the corpora rarely come with good measures of semantic complexity. To ... More
Reachability Problems for Continuous Chemical Reaction NetworksAug 17 2015Sep 03 2015Chemical reaction networks (CRNs) model the behavior of molecules in a well-mixed system. The emerging field of molecular programming uses CRNs not only as a descriptive tool, but as a programming language for chemical computation. Recently, Chen, Doty ... More
Anti-flow of K$^0_s$ Mesons in 6 AGeV Au + Au CollisionsJan 06 2001We have measured the sideward flow of neutral strange ($K^0_s$) mesons in 6 AGeV Au + Au collisions. A prominent anti-flow signal is observed for an impact parameter range (b $\lesssim 7$ fm) which spans central and mid-central events. Since the $K^0_s$ ... More
Directed Flow of $Λ$-Hyperons in 2-6 AGeV Au+Au CollisionsJan 06 2001Directed flow measurements for $\Lambda$-hyperons are presented and compared to those for protons produced in the same Au+Au collisions (2, 4, and 6 AGeV; $b < 5 - 6$ fm). The measurements indicate that $\Lambda$-hyperons flow consistently in the same ... More
An integral formula for the $Q$-prime curvature in 3-dimensional CR geometrySep 15 2017We give an integral formula for the total $Q^\prime$-curvature of a three-dimensional CR manifold with positive CR Yamabe constant and nonnegative Paneitz operator. Our derivation includes a relationship between the Green's functions of the CR Laplacian ... More
Image Reconstruction with a LaBr3-based Rotational ModulatorJun 22 2010Oct 14 2010A rotational modulator (RM) gamma-ray imager is capable of obtaining significantly better angular resolution than the fundamental geometric resolution defined by the ratio of detector diameter to mask-detector separation. An RM imager consisting of a ... More
Self-consistent theory of compact QED3 with relativistic fermionsAug 13 2003Dec 15 2003We consider three dimensional quantum electrodynamics (cQED3) with massless relativistic fermions coupled to a compact gauge field using a combined perturbative variational approach. Coupling to matter renders the bare interaction between magnetic monopoles ... More
Extremal metrics for the $Q^\prime$-curvature in three dimensionsNov 16 2015We construct contact forms with constant $Q^\prime$-curvature on compact three-dimensional CR manifolds which admit a pseudo-Einstein contact form and satisfy some natural positivity conditions. These contact forms are obtained by minimizing the CR analogue ... More
Subspace Condition for Bernstein's Lethargy TheoremJun 25 2016Sep 29 2016In this paper, we consider a condition on subspaces in order to improve bounds given in the Bernstein's Lethargy Theorem (BLT) for Banach spaces. Let $d_1 \geq d_2 \geq \dots d_n \geq \dots > 0$ be an infinite sequence of numbers converging to $0$, and ... More
On the Lichnerowicz conjecture for CR manifolds with mixed signatureJan 31 2018We construct examples of nondegenerate CR manifolds with Levi form of signature $(p,q)$, $2\leq p\leq q$, which are compact, not locally CR flat, and admit essential CR vector fields. We also construct an example of a noncompact nondegenerate CR manifold ... More
Comment on "Minimal conductivity in graphene: Interaction corrections and ultraviolet anomaly" by Mishchenko E. GSep 03 2008In this comment we wish to clarify and correct some of the statements made in a recent paper by E. G. Mishchenko (Europhys. Lett. 83 (2008) 17005).
Noise-Compensating Algebraic Reconstruction for a Rotating Modulation Gamma-Ray ImagerMar 26 2010Oct 12 2010A Rotating Modulator (RM) is one of a class of techniques for indirect imaging of an object scene by modulation and detection of incident photons. Comparison of the RM to more common imaging techniques, the Rotating Modulation Collimator and the coded ... More
Earth Occultation Imaging Applied to BATSE -- Application to a Combined BATSE-GBM Survey of the Hard X-Ray SkyMar 09 2013A combined BATSE-GBM hard X-ray catalog is presented based on Earth Occultation Imaging applied to a reanalysis of BATSE data. An imaging approach has been developed for the reanalysis of Earth Occultation analysis of BATSE data. The standard occultation ... More
Automatic functions, linear time and learningJun 17 2013Sep 16 2013The present work determines the exact nature of {\em linear time computable} notions which characterise automatic functions (those whose graphs are recognised by a finite automaton). The paper also determines which type of linear time notions permit full ... More
Conformally variational Riemannian invariantsNov 15 2017Conformally variational Riemannian invariants (CVIs), such as the scalar curvature, are homogeneous scalar invariants which arise as the gradient of a Riemannian functional. We establish a wide range of stability and rigidity results involving CVIs, generalizing ... More
Nonuniqueness for a fully nonlinear boundary Yamabe-type problem via bifurcation theorySep 01 2018One way to generalize the boundary Yamabe problem posed by Escobar is to ask if a given metric on a compact manifold with boundary can be conformally deformed to have vanishing $\sigma_k$-curvature in the interior and constant $H_k$-curvature on the boundary. ... More
Long term variability of Cygnus X-1 V. State definitions with all sky monitorsMar 05 2013We present a scheme to determine the spectral state of the canonical black hole Cyg X-1 using data from previous and current X-ray all sky monitors (RXTE-ASM, Swift-BAT, MAXI, and Fermi-GBM). State determinations of the hard/intermediate and soft state ... More
The Spitzer c2d Survey of Weak-Line T Tauri Stars. III. The Transition from Primordial Disks to Debris DisksSep 22 2010We present 3.6 to 70 {\mu}m Spitzer photometry of 154 weak-line T Tauri stars (WTTS) in the Chamaeleon, Lupus, Ophiuchus and Taurus star formation regions, all of which are within 200 pc of the Sun. For a comparative study, we also include 33 classical ... More
CASTER - a concept for a Black Hole Finder Probe based on the use of new scintillator technologiesAug 14 2005The primary scientific mission of the Black Hole Finder Probe (BHFP), part of the NASA Beyond Einstein program, is to survey the local Universe for black holes over a wide range of mass and accretion rate. One approach to such a survey is a hard X-ray ... More
Experimental characterization of railgun-driven supersonic plasma jets motivated by high energy density physics applicationsOct 22 2012Dec 11 2012We report experimental results on the parameters, structure, and evolution of high-Mach-number (M) argon plasma jets formed and launched by a pulsed-power-driven railgun. The nominal initial average jet parameters in the data set analyzed are density ... More
Three years of Fermi GBM Earth Occultation Monitoring: Observations of Hard X-ray/Soft Gamma-Ray SourcesJan 17 2012Jun 22 2012The Gamma ray Burst Monitor (GBM) on board Fermi has been providing continuous data to the astronomical community since 2008 August 12. In this paper we present the results of the analysis of the first three years of these continuous data using the Earth ... More
First Results from Fermi GBM Earth Occultation Monitoring: Observations of Soft Gamma-Ray Sources Above 100 keVSep 24 2010The NaI and BGO detectors on the Gamma-ray Burst Monitor (GBM) on Fermi are now being used for long-term monitoring of the hard X-ray/low energy gamma-ray sky. Using the Earth occultation technique as demonstrated previously by the BATSE instrument on ... More
Three years of Fermi GBM Earth Occultation Monitoring: Observations of Hard X-ray/Soft Gamma-Ray SourcesApr 05 2013The Gamma ray Burst Monitor (GBM) on board Fermi Gamma-ray Space Telescope has been providing continuous data to the astronomical community since 2008 August 12. We will present the results of the analysis of the first three years of these continuous ... More
Hot Stars: Old-Fashioned or Trendy?Dec 10 2002Jan 16 2003Spectroscopic analyses with the intention of the interpretation of the UV-spectra of the brightest stars as individuals - supernovae - or as components of star-forming regions - massive O stars - provide a powerful tool with great astrophysical potential ... More
Nuclear shadowing at low Q^2Aug 12 2002Jan 22 2003We re-examine the role of vector meson dominance in nuclear shadowing at low Q^2. We find that models which incorporate both vector meson and partonic mechanisms are consistent with both the magnitude and the Q^2 slope of the shadowing data.
Deep inelastic scattering from light nucleiJul 17 2002We review recent developments in the study of deep inelastic scattering from light nuclei, focusing in particular on deuterium, helium, and lithium. Understanding the nuclear effects in these systems is essential for the extraction of information on the ... More
Neutron/Proton Structure Function Ratio at Large xFeb 26 1996We re-examine the large-x neutron/proton structure function ratio extracted from the latest deuteron data, taking into account the most recent developments in the treatment of Fermi motion, binding and nucleon off-shell effects in the deuteron. Our findings ... More
Q**2 Dependence of Nuclear ShadowingAug 16 1995We re-examine the predictions of a two-phase model of shadowing in nuclear deep-inelastic scattering in light of new NMC data on the x, A and Q**2 dependence of the ratios of structure functions. The model, which combines vector meson dominance at low ... More
Deuteron Structure Functions in the Context of Few-Body PhysicsAug 29 1997Few-body systems offer a unique challenge to those interested in deep inelastic scattering. Using the deuteron as the simplest and most easily solvable nuclear system we review the main physics issues in the valence and sea quark regimes. For the former ... More
Pion Content of the Nucleon in Polarized Semi-Inclusive D.I.sOct 10 1994An explicit pionic component of the nucleon may be identified by measuring polarized $\Delta^{++}$ fragments produced in deep-inelastic scattering off polarized protons. The pion-exchange model predicts highly correlated polarizations of the $\Delta^{++}$ ... More
Parton distributions from lattice QCDAug 02 2001Sep 27 2001We extract the x dependence of the nonsinglet u-d distribution function in the nucleon from the lowest few moments calculated on the lattice, using an extrapolation formula which ensures the correct behavior in the chiral and heavy quark limits. We discuss ... More
Parton distribution functions in the pion from lattice QCDMar 21 2003Jun 30 2003We analyze the moments of parton distribution functions in the pion calculated in lattice QCD, paying particular attention to their chiral extrapolation. Using the lowest three non-trivial moments calculated on the lattice, we assess the accuracy with ... More
Moments of Isovector Quark Distributions in Lattice QCDOct 16 2002We investigate the connection of lattice calculations of moments of isovector parton distributions to the physical regime through extrapolations in the quark mass. We consider the one pion loop renormalisation of the nucleon matrix elements of the corresponding ... More
The Stability of Nuclear Matter in the Nambu-Jona-Lasinio ModelMay 08 2001Using the Nambu-Jona-Lasinio model to describe the nucleon as a quark-diquark state, we discuss the stability of nuclear matter in a hybrid model for the ground state at finite nucleon density. It is shown that a simple extension of the model to simulate ... More
Nuclear Shadowing at Small x and Q^2Oct 05 1993Oct 06 1993Shadowing corrections to structure functions of heavy nuclei are calculated at very low values of Bjorken-$x$ and at values of the momentum transfer relevant to recent experiments. Good agreement is obtained with data from the E665 Collaboration for Xe/D ... More
Extraction of parton distributions from lattice QCDOct 02 2003We review the calculation of moments of both the polarized and unpolarized parton distribution functions of the nucleon in lattice QCD, and in particular their extrapolation to the physical region. We also discuss the reconstruction of the x dependence ... More