Results for "Brian J. Reich"

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A multivariate semiparametric Bayesian spatial modeling framework for hurricane surface wind fieldsSep 04 2007Storm surge, the onshore rush of sea water caused by the high winds and low pressure associated with a hurricane, can compound the effects of inland flooding caused by rainfall, leading to loss of property and loss of life for residents of coastal areas. ... More
Estimating Atmospheric Motion Winds from Satellite Image Data using Space-time Drift ModelsFeb 25 2019Geostationary satellites collect high-resolution weather data comprising a series of images which can be used to estimate wind speed and direction at different altitudes. The Derived Motion Winds (DMW) Algorithm is commonly used to process these data ... More
Discussion of "Estimating the historical and future probabilities of large terrorist event" by Aaron Clauset and Ryan WoodardJan 10 2014Discussion of "Estimating the historical and future probabilities of large terrorist events" by Aaron Clauset and Ryan Woodard [arXiv:1209.0089].
A Test for Isotropy on a Sphere using Spherical Harmonic FunctionsNov 11 2017Nov 15 2017Analysis of geostatistical data is often based on the assumption that the spatial random field is isotropic. This assumption, if erroneous, can adversely affect model predictions and statistical inference. Nowadays many applications consider data over ... More
A Spatial Bayesian Semiparametric Mixture Model for Positive Definite Matrices with Applications to Diffusion Tensor ImagingMar 18 2019Diffusion tensor imaging (DTI) is a popular magnetic resonance imaging technique used to characterize microstructural changes in the brain. DTI studies quantify the diffusion of water molecules in a voxel using an estimated 3x3 symmetric positive definite ... More
Mixture Likelihood Ratio Scan Statistic for Disease Outbreak DetectionJan 18 2012Early detection of disease outbreaks is of paramount importance to implementing intervention strategies to mitigate the severity and duration of the outbreak. We build methodology that utilizes the characteristic profile of disease outbreaks to reduce ... More
Scalar-on-Image Regression via the Soft-Thresholded Gaussian ProcessApr 12 2016The focus of this work is on spatial variable selection for scalar-on-image regression. We propose a new class of Bayesian nonparametric models, soft-thresholded Gaussian processes and develop the efficient posterior computation algorithms. Theoretically, ... More
High Dimensional Linear Regression via the R2-D2 Shrinkage PriorAug 31 2016We propose a new class of priors for linear regression, the R-square induced Dirichlet Decomposition (R2-D2) prior. The prior is induced by a Beta prior on the coefficient of determination, and then the total prior variance of the regression coefficients ... More
Exploration and inference in spatial extremes using empirical basis functionsAug 01 2018Statistical methods for inference on spatial extremes of large datasets are yet to be developed. Motivated by standard dimension reduction techniques used in spatial statistics, we propose an approach based on empirical basis functions to explore and ... More
Deep Distribution RegressionMar 14 2019Due to their flexibility and predictive performance, machine-learning based regression methods have become an important tool for predictive modeling and forecasting. However, most methods focus on estimating the conditional mean or specific quantiles ... More
A semiparametric Bayesian model for spatiotemporal extremesDec 31 2018In this paper, we consider a Dirichlet process mixture of spatial skew-$t$ processes that can flexibly model the extremes as well as the bulk, with separate parameters controlling spatial dependence in these two parts of the distribution. The proposed ... More
Spatial shrinkage via the product independent Gaussian process priorMay 08 2018Jan 26 2019We study the problem of sparse signal detection on a spatial domain. We propose a novel approach to model continuous signals that are sparse and piecewise smooth as product of independent Gaussian processes (PING) with a smooth covariance kernel. The ... More
MIMIX: a Bayesian Mixed-Effects Model for Microbiome Data from Designed ExperimentsMar 22 2017Recent advances in bioinformatics have made high-throughput microbiome data widely available, and new statistical tools are required to maximize the information gained from these data. For example, analysis of high-dimensional microbiome data from designed ... More
A nonparametric spatial test to identify factors that shape a microbiomeJun 16 2018The advent of high-throughput sequencing technologies has made data from DNA material readily available, leading to a surge of microbiome-related research establishing links between markers of microbiome health and specific outcomes. However, to harness ... More
Data Mining to Investigate the Meteorological Drivers for Extreme Ground Level Ozone EventsApr 30 2015Mar 11 2016This project aims to explore which combinations of meteorological conditions are associated with extreme ground level ozone conditions. Our approach focuses only on the tail by optimizing the tail dependence between the ozone response and functions of ... More
Modeling the effect of temperature on ozone-related mortalityDec 04 2014Climate change is expected to alter the distribution of ambient ozone levels and temperatures which, in turn, may impact public health. Much research has focused on the effect of short-term ozone exposures on mortality and morbidity while controlling ... More
A Markov-switching model for heat wavesMay 15 2014Jun 23 2016Heat waves merit careful study because they inflict severe economic and societal damage. We use an intuitive, informal working definition of a heat wave-a persistent event in the tail of the temperature distribution-to motivate an interpretable latent ... More
Fine-scale spatiotemporal air pollution analysis using mobile monitors on Google Street View vehiclesOct 08 2018Dec 06 2018People are increasingly concerned with understanding their personal environment, including possible exposure to harmful air pollutants. In order to make informed decisions on their day-to-day activities, they are interested in real-time information on ... More
Ensemble filter techniques for intermittent data assimilation - a surveyAug 31 2012This survey paper is written with the intention of giving a mathematical introduction to filtering techniques for intermittent data assimilation, and to survey some recent advances in the field. The paper is divided into three parts. The first part introduces ... More
Explicit representations of 3-dimensional Sklyanin algebras associated to a point of order 2Dec 30 2015Feb 23 2017The representation theory of a 3-dimensional Sklyanin algebra $S$ depends on its (noncommutative projective algebro-) geometric data: an elliptic curve $E$ in $\mathbb{P}^2$, and an automorphism $\sigma$ of $E$ given by translation by a point. Indeed, ... More
G181.1+9.5, a new high-latitude low-surface brightness supernova remnantDec 06 2016More than 90% of the known Milky Way supernova remnants are within 5 degrees of the Galactic Plane. We present the discovery of the supernova remnant G181.1+9.5, a new high-latitude SNR, serendipitously discovered in an ongoing survey of the Galactic ... More
Extreme value analysis for evaluating ozone control strategiesDec 06 2013Tropospheric ozone is one of six criteria pollutants regulated by the US EPA, and has been linked to respiratory and cardiovascular endpoints and adverse effects on vegetation and ecosystems. Regional photochemical models have been developed to study ... More
Spatiotemporal Modeling of Node Temperatures in SupercomputersMay 23 2015May 26 2016Los Alamos National Laboratory (LANL) is home to many large supercomputing clusters. These clusters require an enormous amount of power (~500-2000 kW each), and most of this energy is converted into heat. Thus, cooling the components of the supercomputer ... More
Two results in metric fixed point theoryMar 05 2018We establish two fixed point theorems for certain mappings of contractive type. The first result is concerned with the case where such mappings take a nonempty, closed subset of a complete metric space $X$ into $X$, and the second with an application ... More
A Sino-German $λ$6\ cm polarization survey of the Galactic plane VI. Discovery of supernova remnants G178.2-4.2 and G25.1-2.3Jul 04 2011Supernova remnants (SNRs) were often discovered in radio surveys of the Galactic plane. Because of the surface-brightness limit of previous surveys, more faint or confused SNRs await discovery. The Sino-German $\lambda$6\ cm Galactic plane survey is a ... More
A Sino-German 6cm polarisation survey of the Galactic plane IX. HII regionsJan 03 2019Large-scale radio continuum surveys provide data to get insights into the physical properties of radio sources. HII regions are prominent radio sources produced by thermal emission of ionised gas around young massive stars. We identify and analyse HII ... More
Synchrotron Polarization at High Galactic LatitudeJul 03 2003We present preliminary results from mapping the high-latitude Galactic polarization with the Effelsberg Telescope at $\lambda$21 cm. Structures on the resulting maps are mostly on the scale of several degrees. The results show detection of polarization ... More
New lambda6cm observations of the Cygnus LoopOct 18 2005Radio continuum and polarization observations of the entire Cygnus Loop at 6cm wavelength were made with the Urumqi 25m telescope. The 6cm map is analysed together with recently published maps from the Effelsberg 100m telescope at 21cm and 11cm. The integrated ... More
Magnetic fields of the W4 superbubbleApr 01 2015Superbubbles and supershells are the channels for transferring mass and energy from the Galactic disk to the halo. Magnetic fields are believed to play a vital role in their evolution. We study the radio continuum and polarized emission properties of ... More
A Sino-German 6cm polarization survey of the Galactic plane VII. Small supernova remnantsOct 05 2011We study the spectral and polarization properties of supernova remnants (SNRs) based on our 6cm survey data. The observations were taken from the Sino-German 6cm polarization survey of the Galactic plane. By using the integrated flux densities at 6cm ... More
Parametrization of white matter manifold-like structures using principal surfacesApr 08 2013In this manuscript, we are concerned with data generated from a diffusion tensor imaging (DTI) experiment. The goal is to parameterize manifold-like white matter tracts, such as the corpus callosum, using principal surfaces. We approach the problem by ... More
Nonlinear tube-fitting for the analysis of anatomical and functional structuresApr 15 2011We are concerned with the estimation of the exterior surface and interior summaries of tube-shaped anatomical structures. This interest is motivated by two distinct scientific goals, one dealing with the distribution of HIV microbicide in the colon and ... More
A latent factor model for spatial data with informative missingnessOct 07 2010A large amount of data is typically collected during a periodontal exam. Analyzing these data poses several challenges. Several types of measurements are taken at many locations throughout the mouth. These spatially-referenced data are a mix of binary ... More
Measuring and calibrating Galactic synchrotron emissionDec 22 2008Our position inside the Galaxy requires all-sky surveys to reveal its large-scale properties. The zero-level calibration of all-sky surveys differs from standard 'relative' measurements, where a source is measured in respect to its surroundings. All-sky ... More
Response to a population bottleneck can be used to infer recessive selectionDec 11 2013Mar 21 2014Here we present the first genome wide statistical test for recessive selection. This test uses explicitly non-equilibrium demographic differences between populations to infer the mode of selection. By analyzing the transient response to a population bottleneck ... More
Chirality distribution and transition energies of carbon nanotubesSep 09 2004From resonant Raman scattering on isolated nanotubes we obtained the optical transition energies, the radial breathing mode frequency and Raman intensity of both metallic and semiconducting tubes. We unambiguously assigned the chiral index (n_1,n_2) of ... More
Polarization observations of SNR G156.2+5.7 at lambda 6cmMay 19 2007G156.2+5.7 is a large supernova remnant (SNR) first discovered in the ROSAT X-ray survey but radio observations are rare because of its low surface brightness and large size. Radio continuum and polarization images of the SNR G156.2+5.7 at lambda 6 cm ... More
A Sino-German lambda6 cm polarization survey of the Galactic plane I. Survey strategy and results for the first survey regionNov 20 2006(Abridged) Polarization measurements of the Galactic plane at lambda6 cm probe the interstellar medium (ISM) to larger distances compared to measurements at longer wavelengths, hence enable us to investigate properties of the Galactic magnetic fields ... More
A Sino-German 6cm polarization survey of the Galactic plane IV. The region from 60deg to 129deg longitudeFeb 15 2011Feb 17 2011Linear polarization of diffuse Galactic emission is a signature of magnetic fields in the interstellar medium of our Galaxy. Observations at high frequencies are less affected by Faraday depolarization than those at lower frequencies and are able to detect ... More
The radio spectrum and magnetic field structure of SNR HB3Jun 10 2008Jul 30 2008Evidence for a spectral flattening of the supernova remnant (SNR) HB3 (G132.7+1.3) was recently claimed in literature based on previously published total flux density data, and the flattening was further interpreted as the discovery of thermal bremsstrahlung ... More
The sino-german 6cm polarization survey of the galactic plane: A summaryFeb 09 2012We have finished the 6cm polarization survey of the Galactic plane using the Urumqi 25m radio telescope. It covers 10deg<l<230deg in Galactic longitude and |b| <5deg in Galactic latitude. The new polarization maps not only reveal new properties of the ... More
Notes on Beilinson's "How to glue perverse sheaves"Feb 08 2010Jul 11 2010The titular, foundational work of Beilinson not only gives a technique for gluing perverse sheaves but also implicitly contains constructions of the nearby and vanishing cycles functors of perverse sheaves. These constructions are completely elementary ... More
Einstein's Physical Strategy, Energy Conservation, Symmetries, and Stability: "but Grossmann & I believed that the conservation laws were not satisfied"Mar 24 2016Recent work on the history of General Relativity by Renn, Sauer, Janssen et al. shows that Einstein found his field equations partly by a physical strategy including the Newtonian limit, the electromagnetic analogy, and energy conservation. Such themes ... More
Gauge-Invariant Localization of Infinitely Many Gravitational Energies from All Possible Auxiliary StructuresFeb 08 2009Jul 22 2009The problem of finding a covariant expression for the distribution and conservation of gravitational energy-momentum dates to the 1910s. A suitably covariant infinite-component localization is displayed, reflecting Bergmann's realization that there are ... More
Absolute Objects and Counterexamples: Jones-Geroch Dust, Torretti Constant Curvature, Tetrad-Spinor, and Scalar DensityJun 20 2005Feb 28 2006James L. Anderson analyzed the novelty of Einstein's theory of gravity as its lack of "absolute objects." Michael Friedman's related work has been criticized by Roger Jones and Robert Geroch for implausibly admitting as absolute the timelike 4-velocity ... More
Constrained Dynamics of Universally Coupled Massive Spin 2-spin 0 GravitiesJan 25 2006The 2-parameter family of massive variants of Einstein's gravity (on a Minkowski background) found by Ogievetsky and Polubarinov by excluding lower spins can also be derived using universal coupling. A Dirac-Bergmann constrained dynamics analysis seems ... More
Supernova Remnants as a Probe of Dust Grains in the Interstellar MediumMay 07 2010Interstellar dust grains play a crucial role in the evolution of the galactic interstellar medium (ISM). Despite its importance, however, dust remains poorly understood in terms of its origin, composition, and abundance throughout the universe. Supernova ... More
A non-parametric ensemble transform method for Bayesian inferenceOct 01 2012Jan 14 2013Many applications, such as intermittent data assimilation, lead to a recursive application of Bayesian inference within a Monte Carlo context. Popular data assimilation algorithms include sequential Monte Carlo methods and ensemble Kalman filters (EnKFs). ... More
Superposition in Modulation Spaces with Ultradifferentiable WeightsMar 29 2016In the theory of nonlinear partial differential equations we need to explain superposition operators. For modulation spaces equipped with particular ultradifferentiable weights this was done in \cite{rrs}. In this paper we introduce a class of general ... More
Beyond the Standard Model: LHC Phenomenology, Cosmology from Post-Inflationary Sources, and Dark Matter PhysicsAug 24 2013It is the goal of this dissertation to demonstrate that beyond the standard model, certain theories exist which solve conflicts between observation and theory -- conflicts such as massive neutrinos, dark matter, unstable Higgs vacuum, and recent Planck ... More
Galactic polarization surveysMar 17 2006Following the detection of polarized diffuse Galactic emission in 1962 a number of surveys were undertaken at low frequencies in the following years resulting in important insights on the local magnetic field, polarization of the giant radio loops and ... More
G0.087-0.087, a highly polarized flat spectrum filament near the Galactic Centre ArcFeb 18 200332 GHz observations with the Effelsberg 100-m telescope revealed a highly polarized Galactic Centre filament: G0.087-0.087, running parallel to the well-known Arc structure. It has a similar flat spectrum, but it is an order of magnitude weaker. G0.087-0.087 ... More
Processes, Roles and Their InteractionsFeb 21 2012Taking an interaction network oriented perspective in informatics raises the challenge to describe deterministic finite systems which take part in networks of nondeterministic interactions. The traditional approach to describe processes as stepwise executable ... More
Two limitations of our knowledge of qualitySep 19 2016This article develops a quality notion that is complementary to the system notion. As a major consequence, it becomes clear why quality can be measured only to a certain extend based on the issues of validity and incompleteness. First, there is an inherent ... More
DataDec 23 2017Jun 07 2018The contribution of this article is a data concept that is essentially based on the two concepts of information and computable functionality. In short, data is viewed as typed information. A data type is defined as a pair of a set of distinguishable characters ... More
A Gaussian mixture ensemble transform filterFeb 15 2011Jul 06 2011We generalize the popular ensemble Kalman filter to an ensemble transform filter where the prior distribution can take the form of a Gaussian mixture or a Gaussian kernel density estimator. The design of the filter is based on a continuous formulation ... More
Space-time Philosophy Reconstructed via Massive Nordström Scalar Gravities? Laws vs. Geometry, Conventionality, and UnderdeterminationSep 09 2015Klein-Gordon gravity, 1920s-30s particle physics, and 1890s Neumann-Seeliger modified gravity suggest a "graviton mass term" *algebraic* in the potential. Unlike Nordstr\"om's "massless" theory, massive scalar gravity is invariant under the Poincar\'e ... More
Universally Coupled Massive Gravity, II: Densitized Tetrad and Cotetrad TheoriesOct 10 2011Einstein's equations in a tetrad formulation are derived from a linear theory in flat spacetime with an asymmetric potential using free field gauge invariance, local Lorentz invariance and universal coupling. The gravitational potential can be either ... More
Empirical Equivalence, Artificial Gauge Freedom and a Generalized Kretschmann ObjectionNov 28 2009Einstein considered general covariance to characterize the novelty of his General Theory of Relativity (GTR), but Kretschmann thought it merely a formal feature that any theory could have. The claim that GTR is "already parametrized" suggests analyzing ... More
Equivalent Theories Redefine Hamiltonian Observables to Exhibit Change in General RelativitySep 15 2016Change and local spatial variation are missing in canonical GR's observables as usually defined, part of the problem of time. Definitions can be tested using equivalent formulations, non-gauge and gauge, because they must have equivalent observables and ... More
Data Assimilation: The Schrödinger PerspectiveJul 22 2018Dec 02 2018Data assimilation addresses the general problem of how to combine model-based predictions with partial and noisy observations of the process in an optimal manner. This survey focuses on sequential data assimilation techniques using probabilistic particle-based ... More
Radio polarization observations of large supernova remnants at 6cmApr 07 2013May 31 2014We have observed 79 supernova remnants (SNRs) with the Urumqi 25m telescope at 6cm during the Sino-German 6cm polarization survey of the Galactic plane. We measured flux densities of SNRs at 6cm, some of which are the first ever measured or the measurements ... More
A Sino-German 6 cm polarization survey of the Galactic plane II. The region from 129 degree to 230 degree longitudeApr 23 2010Linearly polarized Galactic synchrotron emission provides valuable information about the properties of the Galactic magnetic field and the interstellar magneto-ionic medium, when Faraday rotation along the line of sight is properly taken into account. ... More
Hopping Conduction via Ionic Liquid Induced Silicon Surface StatesMay 01 2015Aug 24 2015In order to clarify the physics of the gating of solids by ionic liquids (ILs) we have gated lightly doped $p$-Si, which is so well studied that it can be called the "hydrogen atom of solid state physics" and can be used as a test bed for ionic liquids. ... More
Epitaxial LaFeAsOF thin films grown by pulsed laser depositionSep 21 2009Superconducting and epitaxially grown LaFeAsOF thin films were successfully prepared on (001)-oriented LaAlO3 substrates using pulsed laser deposition. The prepared thin films show exclusively a single in-plane orientation with epitaxial relation (001)[100] ... More
The Effect of Disorder in Superfluid Double Layer GrapheneApr 12 2011We investigate the superfluid properties of disordered double layer graphene systems using the non-equilibrium Green's function (NEGF) formalism. The complexity of such a structure makes it imperative to study the effects of lattice vacancies which will ... More
Strong [O III] and [N II] emission lines in globular clusters from photoionized R Corona Borealis star windsOct 28 2010The globular cluster X-ray source CXO J033831.8-352604 in NGC 1399 has recently been found to show strong emission lines of [O III] and [N II] in its optical spectrum in addition to ultraluminous X-ray emission with a soft X-ray spectrum. It was further ... More
Spacing of zeros of Hecke L-functions and the class number problemNov 01 2001We derive strong and effective lower bounds for the class number h(q) of the imaginary quadratic field Q(\sqrt{-q}), conditionally subject to the existence of many small (subnormal) gaps between zeros of the L-function associated with a character of the ... More
A Supergiant Supernova-Blown Bubble in the Spiral Galaxy NGC 1620Dec 06 1994We present UBR and H$\alpha$ imaging of NGC 1620, a highly inclined spiral galaxy that contains a large scale, arc-like feature of radius 3 kpc in its outer disk at a distance of $\sim$ 11 kpc from the center. What is unusual about this arc-like feature ... More
On the Selberg class of Dirichlet series: small weightsApr 01 1992In the study of Dirichlet series with arithmetic significance there has appeared (through the study of known examples) certain expectations, namely (i) if a functional equation and Euler product exists, then it is likely that a type of Riemann hypothesis ... More
Infrared Emission from Supernova Remnants: Formation and Destruction of DustNov 03 2017We review the observations of dust emission in supernova rem- nants (SNRs) and supernovae (SNe). Theoretical calculations suggest that SNe, particularly core-collapse, should make significant quantities of dust, perhaps as much as a solar mass. Observations ... More
Enriched Herds And Finite Quantum GroupoidsMay 15 2010We describe a finite quantum groupoid associated to any finite Vect_k enriched herd.
The Cold Dust Content of the Oxygen-Rich Supernova Remnant G292.0+1.8Aug 11 2016We present far-infrared images of the Galactic oxygen-rich supernova remnant (SNR) G292.0+1.8, acquired with the PACS and SPIRE instruments of the Herschel Space Observatory. We find that the SNR shell is detected in the PACS blue (100 micron) band, but ... More
Limits of small functorsOct 13 2006For a small category K enriched over a suitable monoidal category V, the free completion of K under colimits is the presheaf category [K*,V]. If K is large, its free completion under colimits is the V-category PK of small presheaves on K, where a presheaf ... More
Lognormal properties of SGR 1806-20 and the Possibility of a Quiescent Population of other SGR sourcesJul 21 1998Monte Carlo simulations of long SGR event sequences based on lognormal distributions with a range of time intervals and intensity distribution parameters have been investigated. The main conclusions are that the majority of SGRs with properties similar ... More
A Fokker-Planck reaction model for the epitaxial growth and shape transition of quantum dotsApr 11 2017We construct a Fokker-Planck reaction model to investigate the dynamics of the coupled epitaxial growth and shape transition process of an array of quantum dots. The Fokker-Planck reaction model is based on a coupled system of Fokker-Planck equations ... More
No Escape from the Supernova! Magnetic Imprisonment of Dusty Pinballs by a Supernova RemnantJan 21 2018Motivated by recent measurements of deposits of $^{60}$Fe on the ocean floor and the lunar surface, we model the transport of dust grains containing $^{60}$Fe from a near-Earth (i.e., within 100 pc) supernova (SN). We inject dust grains into the environment ... More
Coauthorship and citation in scientific publishingApr 01 2013A large number of published studies have examined the properties of either networks of citation among scientific papers or networks of coauthorship among scientists. Here, using an extensive data set covering more than a century of physics papers published ... More
Astrophysical Shrapnel: Discriminating Among Near-Earth Stellar Explosion Sources of Live Radioactive IsotopesMay 16 2014Mar 09 2015We consider the production and deposition on Earth of isotopes with half-lives in the range 10$^{5}$ to 10$^{8}$ years that might provide signatures of nearby stellar explosions, extending previous analyses of Core-Collapse Supernovae (CCSNe) to include ... More
A nonparametric Bayesian test of dependenceJan 28 2015In this article, we propose a new method for the fundamental task of testing for dependence between two groups of variables. The response densities under the null hypothesis of independence and the alternative hypothesis of dependence are specified by ... More
Bayesian Nonparametric Policy Search with Application to Periodontal Recall IntervalsOct 10 2018Tooth loss from periodontal disease is a major public health burden in the United States. Standard clinical practice is to recommend a dental visit every six months; however, this practice is not evidence-based, and poor dental outcomes and increasing ... More
Magnons and continua in a magnetized and dimerized spin-1/2 chainJun 30 2014We examine the magnetic field dependent excitations of the dimerized spin-1/2 chain, copper nitrate, with antiferromagnetic intra-dimer exchange $J_1=0.44$ meV and exchange alternation $\alpha=J_2/J_1=0.24$. Magnetic excitations in three distinct regimes ... More
Conformal symmetry classes for pp-wave spacetimesAug 07 2013We determine conformal symmetry classes for the pp-wave spacetimes. This refines the isometry classification scheme given by Sippel and Goenner (1986 {\it Gen. Rel. Grav.} {\bf 18} 1229). It is shown that every conformal Killing vector for the null fluid ... More
Faraday screens associated with local molecular cloudsSep 14 2004Polarization observations at 21cm and 18cm towards the local Taurus molecular cloud complex were made with the Effelsberg 100-m telescope. Highly structured, frequency-dependent polarized emission features were detected. We discuss polarization minima ... More
Twisted geometric Satake equivalence via gerbes on the factorizable grassmannianDec 28 2010Jun 10 2013We prove a generalization of the twisted geometric Satake equivalence of Finkelberg--Lysenko in the context of the factorizable grassmannian of a reductive group G relative to a smooth curve X, similar to Gaitsgory's generalization in "On de Jong's conjecture" ... More
Fixed points of polarity type operatorsAug 30 2017Aug 05 2018A well-known result says that the Euclidean unit ball is the unique fixed point of the polarity operator. This result implies that if, in $\mathbb{R}^n$, the unit ball of some norm is equal to the unit ball of the dual norm, then the norm must be Euclidean. ... More
Replica Density Functional Study of One-Dimensional Hard Core Fluids in Porous MediaJun 03 2004A binary quenched-annealed hard core mixture is considered in one dimension in order to model fluid adsorbates in narrow channels filled with a random matrix. Two different density functional approaches are employed to calculate adsorbate bulk properties ... More
A GPU-Computing Approach to Solar Stokes Profile InversionAug 01 2012We present a new computational approach to the inversion of solar photospheric Stokes polarization profiles, under the Milne-Eddington model, for vector magnetography. Our code, named GENESIS (GENEtic Stokes Inversion Strategy), employs multi-threaded ... More
Killing tensors in pp-wave spacetimesNov 29 2010The formal solution of the second order Killing tensor equations for the general pp-wave spacetime is given. The Killing tensor equations are integrated fully for some specific pp-wave spacetimes. In particular, the complete solution is given for the ... More
Modelling Faraday Screens in the Interstellar MediumMar 05 2004Maps of Galactic polarized continuum emission at 1408, 1660, and 1713 MHz towards the local Taurus molecular cloud complex were made with the Effelsberg 100-m telescope. Minima in the polarized emission which are located at the boundary of a molecular ... More
Detecting K-theory by cyclic homologyAug 31 2005We discuss which part of the rationalized algebraic K-theory of a group ring is detected via trace maps to Hochschild homology, cyclic homology, periodic cyclic or negative cyclic homology.
A high frequency radio study of G11.2-0.3, a historical supernova remnant with a flat spectrum coreApr 24 2001We present radio maps of the historical supernova remnant G11.2-0.3 in the frequency range from 4.85 GHz to 32 GHz. The integrated spectrum with \alpha = -0.50 (S ~ \nu^\alpha) is dominated by its steep spectrum shell emission (\alpha ~ -0.57), although ... More
Coefficients for the Farrell-Jones ConjectureOct 27 2005We introduce the Farrell-Jones Conjecture with coefficients in an additive category with G-action. This is a variant of the Farrell-Jones Conjecture about the algebraic K- or L-Theory of a group ring RG. It allows to treat twisted group rings and crossed ... More
Algebraic $K$-theory, assembly maps, controlled algebra, and trace methodsFeb 07 2017Feb 23 2018We give a concise introduction to the Farrell-Jones Conjecture in algebraic $K$-theory and to some of its applications. We survey the current status of the conjecture, and we illustrate the two main tools that are used to attack it: controlled algebra ... More
On the Adams isomorphism for equivariant orthogonal spectraApr 15 2014Sep 22 2015We give a natural construction and a direct proof of the Adams isomorphism for equivariant orthogonal spectra. More precisely, for any finite group G, any normal subgroup N of G, and any orthogonal G-spectrum X, we construct a natural map A of orthogonal ... More
Discrete gradients for computational Bayesian inferenceMar 01 2019In this paper, we exploit the gradient flow structure of continuous-time formulations of Bayesian inference in terms of their numerical time-stepping. We focus on two particular examples, namely, the continuous-time ensemble Kalman filter and a particle ... More
A McKean optimal transportation perspective on Feynman-Kac formulae with application to data assimilationNov 25 2013Jul 14 2014Data assimilation is the task of combining mathematical models with observational data. From a mathematical perspective data assimilation leads to Bayesian inference problems which can be formulated in terms of Feynman-Kac formulae. In this paper we focus ... More
A note on alternating projections in Hilbert spaceFeb 23 2017We provide a direct proof of a result regarding the asymptotic behavior of alternating nearest point projections onto two closed and convex sets in a Hilbert space. Our arguments are based on nonexpansive mapping theory.
The impact of short term synaptic depression and stochastic vesicle dynamics on neural variabilityOct 25 2012Neural variability plays a central role in neural coding and neuronal network dynamics. Unreliability of synaptic transmission is a major source of neural variability: synaptic neurotransmitter vesicles are released probabilistically in response to presynaptic ... More
Transitivity of Infinite-Dimensional Extensions of Anosov DiffeomorphismsSep 10 2012We consider extensions of Anosov diffeomorphisms of an infranilmanifold by the real vector space R^{\omega}. Our main result, based on the analogous theorem in finite dimensions proven by Nitica and Pollicott, is that any Holder cocycle satisfying an ... More