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Results for "Alyson Brooks"

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Re-Examining Astrophysical Constraints on the Dark Matter ModelJul 28 2014Recent high-resolution simulations that include Cold Dark Matter (CDM) and baryons have shown that baryonic physics can dramatically alter the dark matter structure of galaxies. These results modify our predictions for observed galaxy evolution and structure. ... More
Toward the Formation of Realistic Galaxy DisksMar 19 2010In this review I demonstrate that a realistic model for the formation of galaxy disks depends on a proper treatment of the gas in galaxies. Historically, cosmological simulations of disk galaxy formation have suffered from a lack of resolution and a physically ... More
Why Baryons Matter: The Kinematics of Dwarf Spheroidal SatellitesJul 10 2012Apr 28 2014We use high resolution cosmological simulations of Milky Way-mass galaxies that include both baryons and dark matter to show that baryonic physics (energetic feedback from supernovae and subsequent tidal stripping) significantly reduces the dark matter ... More
The Contribution Of Outer HI Disks To The Merging Binary Black Hole PopulationOct 25 2017We investigate the contribution of outer HI disks to the observable population of merging black hole binaries. Like dwarf galaxies, the outer HI disks of spirals have low star formation rates and lower metallicities than the inner disks of spirals. Since ... More
The minimum $b_2$ problem for right-angled Artin groupsJan 10 2014This paper focuses on tools for constructing 4-manifolds that have fundamental group $G$ isomorphic to a right-angled Artin group and that are also minimal, in the sense that they minimize $b_2(M)$, the dimension of $H_2(M;\mathbb{Q})$. For a finitely ... More
Spaces With Complexity OneDec 11 2017An $A$-cellular space is a space built from $A$ and its suspensions, analogously to the way that $CW$-complexes are built from $S^0$ and its suspensions. The $A$-cellular approximation of a space $X$ is an $A$-cellular space $CW_{A}X$ which is closest ... More
Bulge Formation via Mergers in Cosmological SimulationsNov 12 2015The latest generation of cosmological simulations are on the verge of being able to resolve the structure of bulges for the first time. Hence, we review the current state of bulge formation in cosmological simulations, and discuss open questions that ... More
The small-scale structure of the Magellanic StreamSep 13 2001We have mapped in neutral hydrogen (HI) two regions at the northern tip of the Magellanic Stream, known as MS V and MS VI, using the Arecibo telescope. The small-scale structure of the MS shows clumpy and head-tail morphology. The spatial power spectrum ... More
A Baryonic Solution to the Missing Satellites ProblemSep 24 2012Apr 29 2013It has been demonstrated that the inclusion of baryonic physics can alter the dark matter densities in the centers of low-mass galaxies, making the central dark matter slope more shallow than predicted in pure cold dark matter simulations. This flattening ... More
Implementing Dust Shielding as a Criteria for Star FormationJan 03 2019Star formation is observed to be strongly correlated to dense regions of molecular gas. Although the exact nature of the link between star formation and molecular hydrogen is still unclear, some have suggested that shielding of dense gas by dust grains ... More
The Role of Baryons in Creating Statistically Significant Planes of Satellites around Milky Way-Mass GalaxiesOct 10 2016We investigate whether the inclusion of baryonic physics influences the formation of thin, coherently rotating planes of satellites such as those seen around the Milky Way and Andromeda. For four Milky Way-mass simulations, each run both as dark matter-only ... More
Orthogonal Matching Pursuit: A Brownian Motion AnalysisMay 30 2011A well-known analysis of Tropp and Gilbert shows that orthogonal matching pursuit (OMP) can recover a k-sparse n-dimensional real vector from 4 k log(n) noise-free linear measurements obtained through a random Gaussian measurement matrix with a probability ... More
Direct Detections of Young Stars in Nearby Elliptical GalaxiesMay 04 2012Apr 19 2013Small amounts of star formation in elliptical galaxies are suggested by several results: surprisingly young ages from optical line indices, cooling X-ray gas, and mid-IR dust emission. Such star formation has previously been difficult to directly detect, ... More
Multimessenger Signatures of Massive Black Holes in Dwarf GalaxiesJun 01 2018Oct 19 2018Recent discoveries of massive black holes (MBHs) in dwarf galaxies suggest that they may have a more common presence than once thought. Systematic searches are revealing more candidates, but this process could be accelerated by predictions from simulations. ... More
Roll of the Dice: A Stochastically Sampled IMF Alters the StellarContent of Simulated Dwarf GalaxiesOct 31 2018Cosmological simulations are reaching the resolution necessary to study ultra-faint dwarf galaxies. Observations indicate that in small populations, the stellar initial mass function (IMF) is not fully populated; rather, stars are sampled in a way that ... More
The Relative Role of Galaxy Mergers and Cosmic Flows in Feeding Black HolesJul 02 2013Dec 09 2013Using a set of zoomed-in cosmological simulations of high-redshift progenitors of massive galaxies, we isolate and trace the history of gas that is accreted by central supermassive black holes. We determine the origins of the accreted gas, in terms of ... More
The central slope of dark matter cores in dwarf galaxies: Simulations vs. THINGSNov 11 2010Apr 15 2011We make a direct comparison of the derived dark matter (DM) distributions between hydrodynamical simulations of dwarf galaxies assuming a LCDM cosmology and the observed dwarf galaxies sample from the THINGS survey in terms of (1) the rotation curve shape ... More
Angular Momentum Evolution in Dark Matter HalosJun 22 2010Dec 06 2010We have analyzed high resolution N-body simulations of dark matter halos, focusing specifically on the evolution of angular momentum. We find that not only is individual particle angular momentum not conserved, but the angular momentum of radial shells ... More
Assessing Astrophysical Uncertainties in Direct Detection with Galaxy SimulationsJan 20 2016Jul 29 2016We study the local dark matter velocity distribution in simulated Milky Way-mass galaxies, generated at high resolution with both dark matter and baryons. We find that the dark matter in the Solar neighborhood is influenced appreciably by the inclusion ... More
Reignition of Star Formation in Dwarf GalaxiesFeb 08 2018Oct 12 2018The Local Group hosts a number of star-forming dwarf galaxies that show evidence of periods of little to no star formation. We use a suite of cosmological simulations to study how star formation is reignited in such galaxies. We focus on isolated galaxies ... More
The effects of host galaxy properties on merging compact binaries detectable by LIGOSep 21 2016Cosmological simulations of galaxy formation can produce present-day galaxies with a large range of assembly and star formation histories. A detailed study of the metallicity evolution and star formation history of such simulations can assist in predicting ... More
The Dual Origin of Stellar HalosApr 22 2009Jul 20 2009We investigate the formation of the stellar halos of four simulated disk galaxies using high resolution, cosmological SPH + N-Body simulations. These simulations include a self-consistent treatment of all the major physical processes involved in galaxy ... More
Interpreting the Evolution of the Size - Luminosity Relation for Disk Galaxies from Redshift 1 to the PresentNov 01 2010A sample of very high resolution cosmological disk galaxy simulations is used to investigate the evolution of galaxy disk sizes back to redshift 1 within the Lambda CDM cosmology. Artificial images in the rest frame B band are generated, allowing for ... More
Kinematic Evolution of Simulated Star-Forming GalaxiesJun 19 2014Recent observations have shown that star-forming galaxies like our own Milky Way evolve kinematically into ordered thin disks over the last ~8 billion years since z=1.2, undergoing a process of "disk settling." For the first time, we study the kinematic ... More
The Formation of Polar Disk GalaxiesFeb 07 2008Feb 08 2008Polar Ring Galaxies, such as NGC4650A, are a class of galaxy which have two kinematically distinct components that are inclined by almost 90 degrees to each other. These striking galaxies challenge our understanding of how galaxies form; the origin of ... More
Tracing Outflowing Metals in Simulations of Dwarf and Spiral GalaxiesAug 23 2018We analyze the metal accumulation in dwarf and spiral galaxies by following the history of metal enrichment and outflows in a suite of twenty high-resolution simulated galaxies. These simulations agree with the observed stellar and gas-phase mass-metallicity ... More
The Dual Origin of Stellar Halos II: Chemical Abundances as Tracers of Formation HistoryApr 21 2010Jul 28 2010Fully cosmological, high resolution N-Body + SPH simulations are used to investigate the chemical abundance trends of stars in simulated stellar halos as a function of their origin. These simulations employ a physically motivated supernova feedback recipe, ... More
Persistence Lenses: Segmentation, Simplification, Vectorization, Scale Space and Fractal Analysis of ImagesApr 25 2016Jun 21 2016A persistence lens is a hierarchy of disjoint upper and lower level sets of a continuous luminance image's Reeb graph. The boundary components of a persistence lens's interior components are Jordan curves that serve as a hierarchical segmentation of the ... More
The Variation of Rotation Curve Shapes as a Signature of the Effects of Baryons on Dark Matter Density ProfilesMay 31 2015Oct 16 2015Rotation curves of galaxies show a wide range of shapes, which can be paramaterized as scatter in Vrot(1kpc)/Vmax i.e.the ratio of the rotation velocity measured at 1kpc and the maximum measured rotation velocity. We examine whether the observed scatter ... More
Damped Lyman Alpha Systems in Galaxy Formation SimulationsApr 29 2008Oct 17 2008We investigate the population of z=3 damped Lyman alpha absorbers (DLAs) in a recent series of high resolution galaxy formation simulations. The simulations are of interest because they form at z=0 some of the most realistic disk galaxies to date. No ... More
Where are the Intermediate Mass Black Holes?Mar 19 2019Observational evidence has been mounting for the existence of intermediate mass black holes (IMBHs, 10^2-10^5 Msun), but observing them at all, much less constraining their masses, is very challenging. In one theorized formation channel, IMBHs are the ... More
The Distribution of Disk-Halo HI Clouds in the Inner Milky WayJan 20 2011Using data from the Galactic All-Sky Survey, we have compared the properties and distribution of HI clouds in the disk-halo transition at the tangent points in mirror-symmetric regions of the first quadrant (QI) and fourth quadrant (QIV) of the Milky ... More
Particle tagging and its implications for stellar population dynamicsFeb 23 2015We establish a controlled comparison between the properties of galactic stellar halos obtained with hydrodynamical simulations and with `particle tagging'. Tagging is a fast way to obtain stellar population dynamics: instead of tracking gas and star formation, ... More
A rumble in the dark: signatures of self-interacting dark matter in Super-Massive Black Hole dynamics and galaxy density profilesJan 16 2017May 16 2017We explore for the first time the effect of self-interacting dark matter (SIDM) on the dark matter (DM) and baryonic distribution in massive galaxies formed in hydrodynamical cosmological simulations, including explicit baryonic physics treatment. A novel ... More
Angular Momentum Acquisition in Galaxy HalosJan 14 2013Jul 25 2013We use high-resolution cosmological hydrodynamic simulations to study the angular momentum acquisition of gaseous halos around Milky Way sized galaxies. We find that cold mode accreted gas enters a galaxy halo with ~70% more specific angular momentum ... More
Misaligned Angular Momentum in Hydrodynamic Cosmological Simulations: Warps, Outer Discs, and Thick DiscsJun 08 2010We present a detailed analysis of a disc galaxy forming in a high-resolution fully cosmological simulation to investigate the nature of the outer regions of discs and their relevance for the disc formation process. Specifically, we focus on the phenomenon ... More
The Physics Inside Topological Quantum Field TheoriesDec 01 1995We show that the equations of motion defined over a specific field space are realizable as operator conditions in the physical sector of a generalized Floer theory defined over that field space. The ghosts associated with such a construction are found ... More
Diff(SIGMA) and Metrics from Hamiltonian-TQFT's in 2+1 DimensionsDec 23 1992The constraints of $BF$ topological gauge theories are used to construct Hamiltonians which are anti-commutators of the BRST and anti-BRST operators. Such Hamiltonians are a signature of Topological Quantum Field Theories (TQFT's). By construction, both ... More
Moduli Space Cohomology and Wavefunctions in 3D Quantum GravitySep 23 1994Wavefunctionals of three dimensional quantum gravity are extracted from the 3D field theoretic analogs of the four dimensional Donaldson polynomials. Our procedure is generalizable to four and other dimensions. This is a summary of a talk presented at ... More
D-branes and Cosmological SingularitiesJul 25 2001Jul 27 2001The motion of a test Dq-brane in a Dp-brane background is studied. The induced metric on the test brane is then interpreted as the cosmology of the test brane universe. One is then able to resolve the resulting cosmological singularities. In particular, ... More
In-N-Out: the gas cycle from dwarfs to spiral galaxiesJul 31 2015We examine the scalings of galactic outflows with halo mass across a suite of twenty high-resolution cosmological zoom galaxy simulations covering halo masses from 10^9.5 - 10^12 M_sun. These simulations self-consistently generate outflows from the available ... More
Delayed Star Formation in Isolated Dwarf Galaxies: HST Star Formation History of the Aquarius Dwarf IrregularSep 04 2014We have obtained deep images of the highly isolated (d = 1 Mpc) Aquarius dwarf irregular galaxy (DDO 210) with the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). The resulting color-magnitude diagram (CMD) reaches more than a magnitude ... More
Constraints on the Shape of the Milky Way Dark Matter Halo from Jeans Equations Applied to SDSS DataSep 12 2012We search for evidence of dark matter in the Milky Way by utilizing the stellar number density distribution and kinematics measured by the Sloan Digital Sky Survey (SDSS) to heliocentric distances exceeding ~10 kpc. We employ the cylindrically symmetric ... More
Consequences of bursty star formation on galaxy observables at high redshiftsAug 25 2014May 15 2015The star formation histories (SFHs) of dwarf galaxies are thought to be \emph{bursty}, with large -- order of magnitude -- changes in the star formation rate on timescales similar to O-star lifetimes. As a result, the standard interpretations of many ... More
Dancing in the Dark: Uncertainty in ultra-faint dwarf galaxy predictions from cosmological simulationsOct 29 2018Feb 08 2019The existence of ultra-faint dwarf (UFD) galaxies highlights the need to push our theoretical understanding of galaxies to extremely low mass. We examine the formation of UFDs by twice running a fully cosmological simulations of dwarf galaxies, but varying ... More
Effects of Inclination on Measuring Velocity Dispersion and Implications for Black HolesMay 01 2014Sep 23 2014The relation of central black hole mass and stellar spheroid velocity dispersion (the M-$\sigma$ relation) is one of the best-known and tightest correlations linking black holes and their host galaxies. There has been much scrutiny concerning the difficulty ... More
The effect of models of the interstellar media on the central mass distribution of galaxiesNov 01 2012Jan 24 2014We compare the central mass distribution of galaxies simulated with three different models of the interstellar medium (ISM) with increasing complexity: primordial (H+He) cooling down to 10^4K, additional cooling via metal lines and to lower temperatures, ... More
The nature of HI absorbers in GRB afterglows: clues from hydrodynamic simulationsSep 07 2009Dec 04 2009In recent work, we have shown that it is possible to link quantitatively many aspects of damped Lyman alpha (DLA) absorbers in the spectra of quasars to high resolution simulations of galaxy formation. Using runs from the same series of hydrodynamic numerical ... More
Search for Gamma-ray Emission from Dark Matter Annihilation in the Large Magellanic Cloud with the Fermi Large Area TelescopeFeb 03 2015Apr 15 2015At a distance of 50 kpc and with a dark matter mass of $\sim10^{10}$ M$_{\odot}$, the Large Magellanic Cloud (LMC) is a natural target for indirect dark matter searches. We use five years of data from the Fermi Large Area Telescope (LAT) and updated models ... More
Search for Gamma-ray Emission from Dark Matter Annihilation in the Small Magellanic Cloud with the Fermi Large Area TelescopeMar 03 2016Mar 29 2016The Small Magellanic Cloud (SMC) is the second-largest satellite galaxy of the Milky Way and is only 60 kpc away. As a nearby, massive, and dense object with relatively low astrophysical backgrounds, it is a natural target for dark matter indirect detection ... More
At the heart of the matter: the origin of bulgeless dwarf galaxies and Dark Matter coresNov 11 2009For almost two decades the properties of "dwarf" galaxies have challenged the Cold Dark Matter (CDM) paradigm of galaxy formation. Most observed dwarf galaxies consists of a rotating stellar disc embedded in a massive DM halo with a near constant-density ... More
Varilets: Additive Decomposition, Topological Total Variation, and Filtering of Scalar FieldsMar 16 2015Apr 26 2016Continuous interpolation of real-valued data is characterized by piecewise monotone functions on a compact metric space. Topological total variation of piecewise monotone function f:X->R is a homeomorphism-invariant generalization of 1D total variation. ... More
Retinal Vessel Segmentation Using A New Topological MethodAug 03 2016A novel topological segmentation of retinal images represents blood vessels as connected regions in the continuous image plane, having shape-related analytic and geometric properties. This paper presents topological segmentation results from the DRIVE ... More
Relating Scattering Amplitudes in Bosonic and Topological String TheoriesMar 11 1992A formal relationship between scattering amplitudes in critical bosonic string theory and correlation functions of operators in topological string theory is found.
The Cosmological Constant and Volume-Preserving Diffeomorphism InvariantsOct 01 1993Nov 04 1993Observables in the quantum field theories of $(D-1)$-form fields, $\ca$, on $D$-dimensional, compact and orientable manifolds, $M$, are computed. Computations of the vacuum value of $T_{ab}$ find it to be the metric times a function of the volume of spacetime, ... More
Theory and Phenomenology of Dirac LeptogenesisDec 26 2007Dirac leptogenesis, in which neutrinos are purely Dirac and develop small but nonzero effective masses without the aid of the see-saw mechanism, provides an interesting alternative to the standard leptogenesis picture. Here we review the theory and phenomenology ... More
Requirements to Detect the Monoenergetic Photon Signature of Thermal Cold Dark Matter in PeV-Scale Split SupersymmetryMar 24 2005Split supersymmetry scenarios with PeV-scale scalar masses circumvent many of the restrictions on supersymmetry coming from experimental limits on CP violation, flavor-changing neutral currents, and the Higgs boson mass. We consider the situation where ... More
ReliabilityAug 02 2007This special volume of Statistical Sciences presents some innovative, if not provocative, ideas in the area of reliability, or perhaps more appropriately named, integrated system assessment. In this age of exponential growth in science, engineering and ... More
Fixed Points of Generalized Approximate Message Passing with Arbitrary MatricesJan 26 2013May 02 2016The estimation of a random vector with independent components passed through a linear transform followed by a componentwise (possibly nonlinear) output map arises in a range of applications. Approximate message passing (AMP) methods, based on Gaussian ... More
Expectation Consistent Approximate Inference: Generalizations and ConvergenceFeb 25 2016Approximations of loopy belief propagation, including expectation propagation and approximate message passing, have attracted considerable attention for probabilistic inference problems. This paper proposes and analyzes a generalization of Opper and Winther's ... More
Asymptotic Analysis of MAP Estimation via the Replica Method and Applications to Compressed SensingJun 17 2009Oct 08 2011The replica method is a non-rigorous but well-known technique from statistical physics used in the asymptotic analysis of large, random, nonlinear problems. This paper applies the replica method, under the assumption of replica symmetry, to study estimators ... More
The Spitzer Space Telescope First-Look Survey: KPNO MOSAIC-1 R-band Images and Source CatalogsMar 20 2004(Abridged) We present R-band images covering more than 11 square degrees of sky obtained with the KPNO 4-m telescope in preparation for the Spitzer Space Telescope First Look Survey. The FLS was designed to characterize the mid-infrared sky at depths ... More
Detecting Mapping SpacesMar 13 2019We show if $A$ is a finite CW-complex such that algebraic theories detect mapping spaces out of $A$, then $A$ has the homology type of a wedge of spheres of the same dimension. Furthermore, if $A$ is simply connected then $A$ has the homotopy type of ... More
Beta Dips in the Gaia Era: Simulation Predictions of the Galactic Velocity Anisotropy Parameter for Stellar HalosApr 20 2017Feb 03 2018The velocity anisotropy parameter, beta, is a measure of the kinematic state of orbits in the stellar halo which holds promise for constraining the merger history of the Milky Way (MW). We determine global trends for beta as a function of radius from ... More
Where are the Intermediate Mass Black Holes?Mar 19 2019Mar 22 2019Observational evidence has been mounting for the existence of intermediate mass black holes (IMBHs, 10^2-10^5 Msun), but observing them at all, much less constraining their masses, is very challenging. In one theorized formation channel, IMBHs are the ... More
Baryons Matter: Why Luminous Satellite Galaxies Have Reduced Central MassesJun 29 2012Dec 04 2012Using high resolution cosmological hydrodynamical simulations of Milky Way-massed disk galaxies, we demonstrate that supernovae feedback and tidal stripping lower the central masses of bright (-15 < M_V < -8) satellite galaxies. These simulations resolve ... More
The Milky Way Tomography with SDSS. V. Mapping the Dark Matter HaloAug 22 2014Nov 24 2014We present robust constraints from the Sloan Digital Sky Survey (SDSS) on the shape and distribution of the dark matter halo within the Milky Way (MW). Using the number density distribution and kinematics of SDSS halo stars, we probe the dark matter distribution ... More
Cosmological Hydrodynamic Simulations of Preferential Accretion in the SMBH of Milky Way Size GalaxiesOct 04 2016Jun 05 2018Using a new, high-resolution cosmological hydrodynamic simulation of a Milky Way-type (MW-type) galaxy, we explore how a merger-rich assembly history affects the mass budget of the central supermassive black hole (SMBH). We examine a MW-mass halo at the ... More
The Resolved Structure and Dynamics of an Isolated Dwarf Galaxy: A VLT and Keck Spectroscopic Survey of WLMFeb 20 2012We present spectroscopic data for 180 red giant branch stars in the isolated dwarf irregular galaxy WLM. Observations of the Calcium II triplet lines in spectra of RGB stars covering the entire galaxy were obtained with FORS2 at the VLT and DEIMOS on ... More
Cosmological Hydrodynamic Simulations of Preferential Accretion in the SMBH of Milky Way Size GalaxiesOct 04 2016Using a new, high-resolution cosmological hydrodynamic simulation of a Milky Way-type (MW-type) galaxy, we explore how a merger-rich assembly history affects the mass budget of the central supermassive black hole (SMBH). We examine a MW-mass halo at the ... More
Inference Networks for Sequential Monte Carlo in Graphical ModelsFeb 22 2016We introduce a new approach for amortizing inference in directed graphical models by learning heuristic approximations to stochastic inverses, designed specifically for use as proposal distributions in sequential Monte Carlo methods. We describe a procedure ... More
A Compilation Target for Probabilistic Programming LanguagesMar 03 2014Jul 10 2014Forward inference techniques such as sequential Monte Carlo and particle Markov chain Monte Carlo for probabilistic programming can be implemented in any programming language by creative use of standardized operating system functionality including processes, ... More
Graph Eigenfunctions and Quantum Unique ErgodicityJun 18 2010We apply the techniques of our previous paper to study joint eigenfunctions of the Laplacian and one Hecke operator on compact congruence surfaces, and joint eigenfunctions of the two partial Laplacians on compact quotients of $\mathbb{H}\times\mathbb{H}$. ... More
Open Access Publishing in Particle Physics: A Brief Introduction for the non-ExpertMay 23 2007Open Access to particle physics literature does not sound particularly new or exciting, since particle physicists have been reading preprints for decades, and arXiv.org for 15 years. However new movements in Europe are attempting to make the peer-reviewed ... More
Ferroelectricity Induced by Incommensurate MagnetismAug 30 2005Ferroelectricity has been found to occur in several insulating systems, such as TbMnO$_3$ (TMO) and Ni$_3$V$_2$O$_8$ (NVO) which have more than one phase with incommensurately modulated long-range magnetic order. Here we give a phenomenological model ... More
Distributed demand-side contingency-service provisioning while minimizing consumer disutility through local frequency measurements and inter-load communicationApr 15 2017Jun 29 2017We consider the problem of smart and flexible loads providing contingency reserves to the electric grid and provide a Distributed Gradient Projection (DGP) algorithm to minimize loads' disutility while providing contingency services. Each load uses locally ... More
A Physics TragedyOct 21 2017Aug 08 2018The measurement problem and three other vexing experiments in quantum physics are described. It is shown how Quantum Field Theory, as formulated by Julian Schwinger, provides simple solutions for all four experiments. It is also shown how this theory ... More
Topological 4-manifolds with right-angled Artin fundamental groupsNov 20 2014Jan 21 2016We classify closed, topological spin 4-manifolds with fundamental group $\pi$ of cohomological dimension $\leq 3$ (up to s-cobordism), after stabilization by connected sum with at most $b_3(\pi)$ copies of $S^2\times S^2$. In general we must also assume ... More
High-Dimensional Bernoulli Autoregressive Process with Long-Range DependenceMar 19 2019We consider the problem of estimating the parameters of a multivariate Bernoulli process with auto-regressive feedback in the high-dimensional setting where the number of samples available is much less than the number of parameters. This problem arises ... More
Recalculation of Proton Compton Scattering in Perturbative QCDApr 15 2000Oct 16 2000At very high energy and wide angles, Compton scattering on the proton (gamma p -> gamma p) is described by perturbative QCD. The perturbative QCD calculation has been performed several times previously, at leading twist and at leading order in alpha_s, ... More
Properties of the diffuse emission around warm loops in solar active regionsJan 23 2019Coronal loops in active regions are the subjects of intensive investigation, but the important diffuse 'unresolved' emission in which they are embedded has received relatively little attention. Here we measure the densities and emission measure (EM) distributions ... More
J/Ψ and Ψ(2S) Production in p-Pb Collisions at 5.02 TeV with ATLASSep 22 2015The production rates of heavy quarkonia in ion-ion collisions provide sensitive probes in the studies of the hot and dense matter formed in these collisions at high energies. However, a reference for understanding the behavior in the hot medium is necessary; ... More
Jet quenching measurements with ATLAS at LHCNov 26 2010A broad program of measurements is planned for heavy ion collisions in ATLAS. With up to a factor of 30 increase in collision energy compared to existing data, significant new insights are anticipated to be obtained with the first data measured. Global ... More
Bayesian Analysis of Loss Ratios Using the Reversible Jump AlgorithmJan 06 2011In this paper we consider the problem of model choice for a set of insurance loss ratios. We use a reversible jump algorithm for our model discrimination and show how the vanilla reversible jump algorithm can be improved on using recent methodological ... More
Nongeometry, Duality Twists, and the WorldsheetNov 11 2005Jan 31 2006In this paper, we use orbifold methods to construct nongeometric backgrounds, and argue that they correspond to the spacetimes discussed in \cite{dh,wwf}. More precisely, we make explicit through several examples the connection between interpolating orbifolds ... More
The LHC Discovery Potential of a Leptophilic HiggsMar 04 2009In this work, we examine a two-Higgs-doublet extension of the Standard Model in which one Higgs doublet is responsible for giving mass to both up- and down-type quarks, while a separate doublet is responsible for giving mass to leptons. We examine both ... More
Phenomenology of Dirac Neutrinogenesis in Split SupersymmetryNov 17 2005In Split Supersymmetry scenarios the possibility of having a very heavy gravitino opens the door to alleviate or completely solve the worrisome "gravitino problem'' in the context of supersymmetric baryogenesis models. Here we assume that the gravitino ... More
A matter of measurement: rotation velocities and the velocity function of dwarf galaxiesJun 01 2015The velocity function derived from large scale surveys can be compared with the predictions of LCDM cosmology, by matching the measured rotation velocities Vrot of galaxies to the maximum circular velocity of dark matter (DM) halos Vmax. For Vrot<50km/s, ... More
Quantum Gravity and Equivariant CohomologyJul 27 1994Aug 09 1994A procedure for obtaining correlation function densities and wavefunctionals for quantum gravity from the Donaldson polynomial invariants of topological quantum field theories, is given. We illustrate how our procedure may be applied to three and four ... More
Q-Exact Actions for BF TheoriesJan 04 1994The actions for all classical (and consequently quantum) $BF$ theories on $n$-manifolds is proven to be given by anti-commutators of hermitian, nilpotent, scalar fermionic charges with Grassmann-odd functionals. In order to show this, the space of fields ... More
Hadronic Multi-Particle Final State Measurements with CLAS at Jefferson LabNov 04 2003Precision measurements in the neutrino sector are becoming increasingly feasible due to the development of relatively high-rate experimental capabilities. These important developments command renewed attention to the systematic corrections needed to interpret ... More
Space-Time Properties of Hadronization from Nuclear Deep Inelastic ScatteringOct 29 2003Hadronization, the process by which energetic quarks evolve into hadrons, has been studied phenomenologically for decades. However, little experimental insight has been gained into the space-time features of this fundamentally non-perturbative process. ... More
Lepton Flavor Violation and Supersymmetric Dirac LeptogenesisJul 26 2006Aug 29 2006Dirac leptogenesis (or Dirac neutrinogenesis), in which neutrinos are purely Dirac particles, is an interesting alternative to the standard leptogenesis scenario. In its supersymmetric version, the modified form of the superpotential required for successful ... More
Using Autoencoders To Learn Interesting Features For Detecting Surveillance AircraftSep 27 2018This paper explores using a Long short-term memory (LSTM) based sequence autoencoder to learn interesting features for detecting surveillance aircraft using ADS-B flight data. An aircraft periodically broadcasts ADS-B (Automatic Dependent Surveillance ... More
Non-negative Curvature and Conullity of the Curvature TensorMar 18 2019The conullity of a curvature tensor is the codimension of its kernel. We consider the cases of conullity two in any dimension and conullity three in dimension four. We show that these conditions are compatible with non-negative sectional curvature only ... More
Absence of HI in the Bootes Dwarf Spheroidal GalaxyNov 21 2006Neutral hydrogen observations towards the Bootes dwarf spheroidal galaxy, a very low luminosity metal-poor Galactic satellite, were obtained using the Parkes Radio Telescope. We do not detect any HI in or around Bootes to a 3sigma upper limit of 180 Msun ... More
Dynamic Stacked Generalization for Node Classification on NetworksOct 16 2016We propose a novel stacked generalization (stacking) method as a dynamic ensemble technique using a pool of heterogeneous classifiers for node label classification on networks. The proposed method assigns component models a set of functional coefficients, ... More
Host-feeding enhances stability of discrete-time host-parasitoid population dynamic modelsMar 06 2015Discrete-time models are the traditional approach for capturing population dynamics of a host-parasitoid system. Recent work has introduced a semi-discrete framework for obtaining model update functions that connect host-parasitoid population levels from ... More
Non-localization of eigenfunctions on large regular graphsDec 16 2009We give a delocalization estimate for eigenfunctions of the discrete Laplacian on large $d+1$-regular graphs, showing that any subset of the graph supporting $\epsilon$ of the $L^2$ mass of an eigenfunction must be large. For graphs satisfying a mild ... More
Survey of Automated Vulnerability Detection and Exploit Generation Techniques in Cyber Reasoning SystemsFeb 20 2017Aug 07 2018Software is everywhere, from mission critical systems such as industrial power stations, pacemakers and even household appliances. This growing dependence on technology and the increasing complexity software has serious security implications as it means ... More