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Results for "Amy B. Knudsen"

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Characterization and valuation of uncertainty of calibrated parameters in stochastic decision modelsJun 11 2019We evaluated the implications of different approaches to characterize uncertainty of calibrated parameters of stochastic decision models (DMs) in the quantified value of such uncertainty in decision making. We used a microsimulation DM of colorectal cancer ... More
Linear Hashing is AwesomeJun 08 2017We consider the hash function $h(x) = ((ax+b) \bmod p) \bmod n$ where $a,b$ are chosen uniformly at random from $\{0,1,\ldots,p-1\}$. We prove that when we use $h(x)$ in hashing with chaining to insert $n$ elements into a table of size $n$ the expected ... More
Additive Spanners: A Simple ConstructionMar 02 2014Nov 23 2014We consider additive spanners of unweighted undirected graphs. Let $G$ be a graph and $H$ a subgraph of $G$. The most na\"ive way to construct an additive $k$-spanner of $G$ is the following: As long as $H$ is not an additive $k$-spanner repeat: Find ... More
A closer look at the stacks of stable pointed curvesJun 08 2011Apr 03 2012In the theory of the moduli-stacks of n-pointed stable curves, there are two fundamental functors, contraction and stabilization. These functors are constructed in [4], where they are used to show that the various \bar{M_{g,n}}'s are DM-stacks. We give ... More
Imaginary Multiquadratic Fields of Class Number 1Aug 15 2016Aug 29 2016In this paper, we present a complete classification of all imaginary $n$-quadratic fields of class number 1.
An exact formula relating lattice points in symmetric spaces to the automorphic spectrumApr 28 2011May 23 2011We extract an exact formula relating the number of lattice points in an expanding region of a complex semi-simple symmetric space and the automorphic spectrum from a spectral identity, which is obtained by producing two expressions for the automorphic ... More
The Entropy of Backwards AnalysisApr 14 2017Backwards analysis, first popularized by Seidel, is often the simplest most elegant way of analyzing a randomized algorithm. It applies to incremental algorithms where elements are added incrementally, following some random permutation, e.g., incremental ... More
Configuration spaces of productsOct 13 2017May 20 2018We show that the configuration spaces of a product of parallelizable manifolds may be recovered from those of the factors as the Boardman-Vogt tensor product of right modules over the operads of little cubes of the appropriate dimension. We also discuss ... More
A multi-platform metabolomics approach identifies novel biomarkers associated with bacterial diversity in the human vaginaApr 10 2015Bacterial vaginosis (BV) increases transmission of HIV, enhances the risk of preterm labour, and its associated malodour impacts the quality of life for many women. Clinical diagnosis primarily relies on microscopy to presumptively detect a loss of lactobacilli ... More
Mapping Hearthstone Deck Spaces through MAP-Elites with Sliding BoundariesApr 24 2019Quality diversity (QD) algorithms such as MAP-Elites have emerged as a powerful alternative to traditional single-objective optimization methods. They were initially applied to evolutionary robotics problems such as locomotion and maze navigation, but ... More
Structural and magnetic properties of GdCo$_{5-x}$Ni$_x$Mar 27 2019GdCo$_5$ may be considered as two sublattices - one of Gd and one of Co - whose magnetizations are in antiparallel alignment, forming a ferrimagnet. Substitution of nickel in the cobalt sublattice of GdCo$_5$ has been investigated to gain insight into ... More
Branching of Automorphic Fundamental SolutionsJan 09 2014Dec 30 2014Automorphic fundamental solutions and, more generally, solutions of automorphic differential equations, play a key role in the Diaconu-Garrett-Goldfeld prescription for spectral identities involving moments of L-functions as well as other applications, ... More
Graphical Mahonian Statistics on WordsJun 30 2016Foata and Zeilberger defined the graphical major index, $\mathrm{maj}'_U$, and the graphical inversion index, $\mathrm{inv}'_U$, for words. These statistics are a generalization of the classical permutation statistics $\mathrm{maj}$ and $\mathrm{inv}$ ... More
Modular representations on some Riemann-Roch spaces of modular curves X(N)Feb 28 2005We compute the PSL(2,N)-module structure of the Riemann-Roch space L(D), where D is an invariant non-special divisor on the modular curve X(N), with N > 5 prime. This depends on a computation of the ramification module, which we give explicitly. These ... More
Representations of finite groups on Riemann-Roch spaces, IIDec 19 2003If G is a finite subgroup of the automorphism group of a projective curve X and D is a divisor on X stabilized by G, then under the assumption that D is nonspecial, we compute a simplified formula for the trace of the natural representation of G on Riemann-Roch ... More
Extending the redshift distribution of submm galaxies: Identification of a z~4 submm galaxyApr 04 2006We present the identification of a bright submillimeter galaxy (SMG) in the field of Abell 2218. The galaxy has a spectroscopic redshift of ~4, and is currently the highest redshift SMG known. It is detected at all wavelengths from optical to submm, including ... More
Power of $d$ Choices with Simple TabulationApr 25 2018Suppose that we are to place $m$ balls into $n$ bins sequentially using the $d$-choice paradigm: For each ball we are given a choice of $d$ bins, according to $d$ hash functions $h_1,\dots,h_d$ and we place the ball in the least loaded of these bins breaking ... More
The spectral energy distribution of the hyperluminous, hot dust-obscured galaxy W2246$-$0526Feb 06 2018Hot dust-obscured galaxies (Hot DOGs) are a luminous, dust-obscured population recently discovered in the WISE All-Sky survey. Multiwavelength follow-up observations suggest that they are mainly powered by accreting supermassive black holes (SMBHs), lying ... More
The NuSTAR X-ray Spectrum of Hercules X-1: A Radiation-Dominated Radiative ShockAug 31 2016We report new spectral modeling of the accreting X-ray pulsar Hercules X- 1. Our radiation-dominated radiative shock model is an implementation of the analytic work of Becker & Wolff on Comptonized accretion flows onto magnetic neutron stars. We obtain ... More
Distribution modulo 1 and the lexicographic worldJul 21 2009Jan 31 2011We give a complete description of the minimal intervals containing all fractional parts $\{\xi 2^n\}$, for some positive real number $\xi$, and for all $n \geq 0$.
Extremal properties of (epi)Sturmian sequences and distribution modulo 1Jul 14 2009Starting from a study of Y. Bugeaud and A. Dubickas (2005) on a question in distribution of real numbers modulo 1 via combinatorics on words, we survey some combinatorial properties of (epi)Sturmian sequences and distribution modulo 1 in connection to ... More
Self-Similar Grooving Solutions to the Mullins' EquationJun 17 2019In 1957, Mullins proposed surface diffusion motion as a model for thermal grooving. By adopting a small slope approximation, he reduced the model to the Mullins' linear surface diffusion equation, \begin{equation} \nonumber ({\rm{ME}})\quad\quad y_t + ... More
Evolution of cosmic star formation in the SCUBA-2 Cosmology Legacy SurveyJul 14 2016Jan 05 2017We present a new exploration of the cosmic star-formation history and dust obscuration in massive galaxies at redshifts $0.5< z<6$. We utilize the deepest 450 and 850$\mu$m imaging from SCUBA-2 CLS, covering 230arcmin$^2$ in the AEGIS, COSMOS and UDS ... More
Fast hashing with Strong Concentration BoundsMay 01 2019May 02 2019Previous work on tabulation hashing of P\v{a}tra\c{s}cu and Thorup from STOC'11 on simple tabulation and from SODA'13 on twisted tabulation offered Chernoff-style concentration bounds on hash based sums, but under some quite severe restrictions on the ... More
Fast hashing with Strong Concentration BoundsMay 01 2019Previous work on tabulation hashing of P\v{a}tra\c{s}cu and Thorup from STOC'11 on simple tabulation and from SODA'13 on twisted tabulation offered Chernoff-style concentration bounds on hash based sums, but under some quite severe restrictions on the ... More
The Gould's Belt Distances Survey (GOBELINS). V. Distances and Kinematics of the Perseus molecular cloudAug 10 2018We derive the distance and structure of the Perseus molecular cloud by combining trigonometric parallaxes from Very Long Baseline Array (VLBA) observations, taken as part of the GOBELINS survey, and Gaia Data Release 2. Based on our VLBA astrometry, we ... More
Context-free Grammars for Permutations and Increasing TreesAug 08 2014In this paper, we introduce the notion of a grammatical labeling to describe a recursive process of generating combinatorial objects based on a context-free grammar. For example, by labeling the ascents and descents of a Stirling permutation, we obtain ... More
On the matrix equation $XA + AX^T = 0$Aug 02 2012Oct 24 2012The matrix equation $XA + AX^T = 0$, which has relevance to the study of Lie algebras, was recently studied by De Teran and Dopico. They reduced the study of this equation to several special cases and produced explicit solutions in most instances. In ... More
Natural Environment Benchmarks for Reinforcement LearningNov 14 2018While current benchmark reinforcement learning (RL) tasks have been useful to drive progress in the field, they are in many ways poor substitutes for learning with real-world data. By testing increasingly complex RL algorithms on low-complexity simulation ... More
Infrared Variability of Two Dusty White DwarfsAug 28 2018The most heavily polluted white dwarfs often show excess infrared radiation from circumstellar dust disks, which are modeled as a result of tidal disruption of extrasolar minor planets. Interaction of dust, gas, and disintegrating objects can all contribute ... More
Gaia-DR2 confirms VLBA parallaxes in Ophiuchus, Serpens and AquilaDec 06 2018We present Gaia-DR2 astrometry of a sample of YSO candidates in Ophiuchus, Serpens Main and Serpens South/W40 in the Aquila Rift, which had been mainly identified by their infrared excess with Spitzer. We compare the Gaia-DR2 parallaxes against published ... More
Order Reconstruction for Nematics on Squares and Regular Polygons: A Landau-de Gennes StudyJun 21 2016We construct an order reconstruction (OR)-type Landau-de Gennes critical point on a square domain of edge length $\lambda$, motivated by the well order reconstruction solution numerically reported by Kralj and Majumdar. The OR critical point is distinguished ... More
Neural network approach to classifying alarming student responses to online assessmentSep 20 2018Automated scoring engines are increasingly being used to score the free-form text responses that students give to questions. Such engines are not designed to appropriately deal with responses that a human reader would find alarming such as those that ... More
New CO detections of lensed submillimeter galaxies in A2218: Probing molecular gas in the LIRG regime at high redshiftDec 17 2008Context: Submillimeter galaxies (SMGs) are distant, dusty galaxies undergoing star formation at prodigious rates. Recently there has been major progress in understanding the nature of the bright SMGs (i.e. S(850um)>5mJy). The samples for the fainter SMGs ... More
Longest Common Extensions in Sublinear SpaceApr 10 2015The longest common extension problem (LCE problem) is to construct a data structure for an input string $T$ of length $n$ that supports LCE$(i,j)$ queries. Such a query returns the length of the longest common prefix of the suffixes starting at positions ... More
The short-lived production of exozodiacal dust in the aftermath of a dynamical instability in planetary systemsJun 03 2013Excess emission, associated with warm, dust belts, commonly known as exozodis, has been observed around a third of nearby stars. The high levels of dust required to explain the observations are not generally consistent with steady-state evolution. A common ... More
A fully non-linear optimization approach to acousto-electric tomographyApr 07 2018Jul 04 2018This paper considers the non-linear inverse problem of reconstructing an electric conductivity distribution from the interior power density in a bounded domain. Applications include the novel tomographic method known as acousto-electric tomography, in ... More
Outbursts and Disk Variability in Be StarsAug 08 2017Jan 23 2018In order to study the growth and evolution of circumstellar disks around classical Be stars, we analyze optical time-series photometry from the KELT survey with simultaneous infrared and visible spectroscopy from the APOGEE survey and BeSS database for ... More
Graph's Topology and Free Energy of a Spin Model on the GraphNov 29 2016In this work we show that there is a direct relationship between a graph's topology and the free energy of a spin system on the graph. We develop a method of separating topological and enthalpic contributions to the free energy, and find that considering ... More
Efficient Modal Decomposition of Vortex Beams via Holographically Reconstructed PhaseOct 09 2017We use phase-shifting digital holography to measure the amplitude and phase of twisted light. In our experiment, a spatial light modulator generates the studied vortex beams in addition to a co-propagating reference beam with a controllable relative phase. ... More
Compaction and Melt Transport in Ammonia-Rich Ice Shells: Implications for the Evolution of TritonNov 27 2018Ammonia, if present in the ice shells of icy satellites, could lower the temperature for the onset of melting to 176 K and create a large temperature range where partial melt is thermally stable. The evolution of regions of ammonia-rich partial melt could ... More
Massive and massless modes of the triplet phase of neutron matterAug 21 2014Sep 12 2014Neutron matter at densities of the order of the nuclear saturation density is believed to have neutrons paired in the 3P2 channel. We study the low lying modes of this phase and find two massless modes (angulons), resulting from the spontaneous breaking ... More
Spatial Statistical Downscaling for Constructing High-Resolution Nature Runs in Global Observing System Simulation ExperimentsNov 01 2017Aug 31 2018Observing system simulation experiments (OSSEs) have been widely used as a rigorous and cost-effective way to guide development of new observing systems, and to evaluate the performance of new data assimilation algorithms. Nature runs (NRs), which are ... More
How the medium shapes the message: Printing and the rise of the arts and sciencesDec 16 2015Aug 09 2017Communication technologies, from printing to social media, affect our historical records by changing the way ideas are spread and recorded. Yet, finding statistical instruments to address the endogeneity of this relationship has been problematic. Here ... More
The Slack Realization Space of a PolytopeAug 16 2017Aug 05 2018In this paper we introduce a natural model for the realization space of a polytope up to projective equivalence which we call the slack realization space of the polytope. The model arises from the positive part of an algebraic variety determined by the ... More
Universality of Rank 6 Plucker Relations and Grassmann Cone Preserving MapsOct 05 2005Jan 29 2007The Plucker relations define a projective embedding of the Grassmann variety Gr(k,n). We give another finite set of quadratic equations which defines the same embedding, and whose elements all have rank 6. This is achieved by constructing a certain finite ... More
Robustness Analysis of Face ObscurationMay 13 2019Face obscuration is often needed by law enforcement or mass media outlets to provide privacy protection. Sharing sensitive content where the obscuration or redaction technique may have failed to completely remove all identifiable traces can lead to life-threatening ... More
Nonparametric Bayes models for mixed-scale longitudinal surveysJun 08 2016Modeling and computation for multivariate longitudinal surveys have proven challenging, particularly when data are not all continuous and Gaussian but contain discrete measurements. In many social science surveys, study participants are selected via complex ... More
Solving multivariate functional equationsJun 28 2012Dec 03 2013This paper presents a new method to solve functional equations of multivariate generating functions, such as $$F(r,s)=e(r,s)+xf(r,s)F(1,1)+xg(r,s)F(qr,1)+xh(r,s)F(qr,qs),$$ giving a formula for $F(r,s)$ in terms of a sum over finite sequences. We use ... More
Two-photon excitation of rubidium atoms inside porous glassJun 15 2017We study the two-photon laser excitation to the 5D$_{5/2}$ energy level of $^{85}$Rb atoms contained in the interstices of a porous material made from sintered ground glass with typical pore dimensions in the 10 - 100 $\mu$m range. The excitation spectra ... More
The Gould's Belt Distances Survey (GOBELINS) I. Trigonometric parallax distances and depth of the Ophiuchus complexNov 20 2016We present the first results of the Gould's Belt Distances Survey (GOBELINS), a project aimed at measuring the proper motion and trigonometric parallax of a large sample of young stars in nearby regions using multi-epoch Very Long Baseline Array (VLBA) ... More
Time-Series Analysis of Broadband Photometry of Neptune from K2Feb 09 2017We report here on our search for excess power in photometry of Neptune collected by the K2 mission that may be due to intrinsic global oscillations of the planet Neptune. To conduct this search, we developed new methods to correct for instrumental effects ... More
Higher enveloping algebrasMay 04 2016We provide Lie algebras with enveloping algebras over the operad of little $n$-dimensional disks for any choice of $n$, and we give two complementary descriptions of these objects. The first description is an abstract characterization by a universal mapping ... More
Betti numbers and stability for configuration spaces via factorization homologyMay 26 2014Aug 14 2015Using factorization homology, we realize the rational homology of the unordered configuration spaces of an arbitrary manifold $M$, possibly with boundary, as the homology of a Lie algebra constructed from the compactly supported cohomology of $M$. By ... More
SDSS-IV MaNGA: The Spatially Resolved Stellar Initial Mass Function in $\sim$400 Early-Type GalaxiesMar 22 2018MaNGA provides the opportunity to make precise spatially resolved measurements of the IMF slope in galaxies owing to its unique combination of spatial resolution, wavelength coverage and sample size. We derive radial gradients in age, element abundances ... More
The Gould's Belt Distances Survey (GOBELINS). IV. Distance, Depth and Kinematics of the Taurus Star-Forming RegionMay 23 2018We present new trigonometric parallaxes and proper motions of young stellar objects in the Taurus molecular cloud complex from observations collected with the Very Long Baseline Array as part of the Gould's Belt Distances Survey (GOBELINS). We detected ... More
The Gould's Belt Distances Survey (GOBELINS) III. The distance to the Serpens/Aquila Molecular ComplexOct 10 2016We report on new distances and proper motions to seven stars across the Serpens/Aquila complex. The observations were obtained as part of the Gould's Belt Distances Survey (GOBELINS) project between September 2013 and April 2016 with the Very Long Baseline ... More
The Gould's Belt Distances Survey (GOBELINS) II. Distances and structure towards the Orion Molecular CloudsSep 13 2016Oct 04 2016We present the results of the Gould's Belt Distances Survey (GOBELINS) of young star forming regions towards the Orion Molecular Cloud Complex. We detected 36 YSOs with the Very Large Baseline Array (VLBA), 27 of which have been observed in at least 3 ... More
Monte Carlo Particle Lists: MCPLSep 09 2016A binary format with lists of particle state information, for interchanging particles between various Monte Carlo simulation applications, is presented. Portable C code for file manipulation is made available to the scientific community, along with converters ... More
Experimental and theoretical study of oxygen adsorption structures on Ag(111)Apr 23 2009Aug 20 2009The oxidized Ag(111) surface has been studied by a combination of experimental and theoretical methods, scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). A large variety of different surface ... More
Paradigms in Physics Education ResearchJul 16 2013Jan 07 2015In this paper, we describe two paradigms in physics education research (PER): recurrence- oriented and case-oriented PER. We connect theory on research methodologies in the social sciences to interviews with physics education researchers and examples ... More
Multi-class Twitter Data Categorization and Geocoding with a Novel Computing FrameworkMay 08 2019Transportation data analysis is becoming a major area of computing application. Operation and management of transportation system have been transforming with the advancements in computing technology. This study presents such an advancement in transportation ... More
Selection, Generalization, and Theories of Cause in Case-Oriented Physics Education ResearchJul 16 2013Jan 07 2015Case-oriented physics education research - which seeks to refine and develop theory by linking that theory to cases - incorporates distinct practices for selecting data for analysis, generalizing results, and making causal claims. Unanswered questions ... More
z~1 Lya Emitters I. The Luminosity FunctionJan 23 2014We construct a flux-limited sample of 135 candidate z~1 Lya emitters (LAEs) from Galaxy Evolution Explorer (GALEX) grism data using a new data cube search method. These LAEs have luminosities comparable to those at high redshifts and lie within a 7 Gyr ... More
Bayesian Local Extrema SplinesApr 04 2016We consider the problem of shape restricted nonparametric regression on a closed set X ?\in R; where it is reasonable to assume the function has no more than H local extrema interior to X: Following a Bayesian approach we develop a nonparametric prior ... More
Elucidating the sign problem through noise distributionsOct 26 2012Due to the presence of light pions in the theory, lattice QCD at finite densities suffers from issues with noise in both grand canonical and canonical formulations. We study two different formulations of the Nambu-Jona-Lasinio model reduced to 2+1 dimensions ... More
Estimation of cell lineage trees by maximum-likelihood phylogeneticsMar 29 2019CRISPR technology has enabled large-scale cell lineage tracing for complex multicellular organisms by mutating synthetic genomic barcodes during organismal development. However, these sophisticated biological tools currently use ad-hoc and outmoded computational ... More
Explicit construction of Ramanujan bigraphsFeb 09 2015We construct explicitly an infinite family of Ramanujan graphs which are bipartite and biregular. Our construction starts with the Bruhat-Tits building of an inner form of $SU_3(\mathbb Q_p)$. To make the graphs finite, we take successive quotients by ... More
Nonstandard regular variation of in-degree and out-degree in the preferential attachment modelMay 19 2014For the directed edge preferential attachment network growth model studied by Bollobas et al. (2003) and Krapivsky and Redner (2001), we prove that the joint distribution of in-degree and out-degree has jointly regularly varying tails. Typically the marginal ... More
Deep Learning Features for Robust Detection of Acoustic Events in Sleep-Disordered BreathingApr 05 2019Sleep-disordered breathing (SDB) is a serious and prevalent condition, and acoustic analysis via consumer devices (e.g. smartphones) offers a low-cost solution to screening for it. We present a novel approach for the acoustic identification of SDB sounds, ... More
Testing the Weak Equivalence Principle using Optical and Near-Infrared Crab PulsesApr 12 2018The Weak Equivalence Principle states that the geodesics of a test particle in a gravitational field are independent of the particle's constitution. To constrain violations of the Weak Equivalence Principle, we use the one-meter telescope at Table Mountain ... More
The Importance of Nebular Continuum and Line Emission in Observations of Young Massive Star ClustersNov 02 2009In this spectroscopic study of infant massive star clusters, we find that continuum emission from ionized gas rivals the stellar luminosity at optical wavelengths. In addition, we find that nebular line emission is significant in many commonly used broad-band ... More
Sign problems, noise, and chiral symmetry breaking in a QCD-like theoryAug 28 2012Jan 24 2013The Nambu-Jona-Lasinio model reduced to 2+1 dimensions has two different path integral formulations: at finite chemical potential one formulation has a severe sign problem similar to that found in QCD, while the other does not. At large N, where N is ... More
An Emerging Wolf-Rayet Massive Star Cluster in NGC 4449Jan 21 2015We present a panchromatic investigation of the partially-embedded, emerging massive cluster Source 26 (= S26) in NGC 4449 with optical spectra obtained at Apache Point Observatory and archival Hubble, Spitzer, and Herschel Space Telescope images. First ... More
High Resolution Radio and Optical Observations of the Central Starburst in the Low-Metallicity Dwarf Galaxy II Zw 40Dec 17 2013The extent to which star formation varies in galaxies with low masses, low metallicities, and high star formation rate surface densities is not well-constrained. To gain insight into star formation under these physical conditions, this paper estimates ... More
Protostars, multiplicity, and disk evolution in the Corona Australis region: A Herschel Gould Belt StudyNov 29 2012The CrA region and the Coronet cluster form a nearby (138 pc), young (1-2 Myr) star-forming region hosting a moderate population of YSO. We present Herschel PACS photometry at 100 and 160 micron, obtained as part of the Herschel Gould Belt Survey. The ... More
The role of evolutionary selection in the dynamics of protein structure evolutionJun 18 2016Oct 25 2016Emergence of new protein structures has proved difficult to trace in nature and engineer in the laboratory. However, one aspect of structure evolution has proved immensely helpful for determining the three-dimensional structure of proteins from their ... More
Photometric Amplitude Distribution of Stellar Rotation of Kepler KOIs-Indication for Spin-Orbit Alignment of Cool Stars and High Obliquity for Hot StarsJan 06 2015The observed amplitude of the rotational photometric modulation of a star with spots should depend on the inclination of its rotational axis relative to our line of sight. Therefore, the distribution of observed rotational amplitudes of a large sample ... More
EUVE Observations of the Magnetic Cataclysmic Variable QQ VulpeculaeNov 30 1999We present simultaneous X-ray (lambda_peak ~ 44A) and EUV (lambda_peak = 89A) light curves for the magnetic cataclysmic variable QQ Vulpeculae, obtained with the EUVE satellite. We find that the unique shape of the X-ray light curve is different from ... More
Non-uniform Information Dissemination for Sensor NetworksAug 10 2004Future smart environments will be characterized by multiple nodes that sense, collect, and disseminate information about environmental phenomena through a wireless network. In this paper, we define a set of applications that require a new form of distributed ... More
The MAterials Simulation Toolkit (MAST) for atomistic modeling of defects and diffusionOct 03 2016The MAterials Simulation Toolkit (MAST) is a workflow manager and post-processing tool for ab initio defect and diffusion workflows. MAST codifies research knowledge and best practices for such workflows, and allows for the generation and management of ... More
Simulation Tools for Detector and Instrument DesignAug 07 2017The high performance requirements at the European Spallation Source have been driving the technological advances on the neutron detector front. Now more than ever is it important to optimize the design of detectors and instruments, to fully exploit the ... More
Depth dependent bounds on distinguishability of inclusions in electrical impedance tomographyFeb 11 2016May 04 2016The inverse problem of electrical impedance tomography is highly ill-posed, and it is often observed that inclusions far from the boundary are difficult to reconstruct. This paper provides rigorous results supporting the intuition. Indeed, lower and upper ... More
Video Human Segmentation using Fuzzy Object Models and its Application to Body Pose Estimation of Toddlers for Behavior StudiesMay 29 2013Video object segmentation is a challenging problem due to the presence of deformable, connected, and articulated objects, intra- and inter-object occlusions, object motion, and poor lighting. Some of these challenges call for object models that can locate ... More
Thermal Energy Grid Storage Using Multijunction PhotovoltaicsJun 18 2018As the cost of renewable energy falls below fossil fuels, the most important challenge to enable widespread sustainable power generation has become making renewables dispatchable. Low cost energy storage can provide this dispatchability, but there is ... More
How do people explore virtual environments?Dec 13 2016Sep 19 2017Understanding how people explore immersive virtual environments is crucial for many applications, such as designing virtual reality (VR) content, developing new compression algorithms, or learning computational models of saliency or visual attention. ... More
Parsec Scale Faraday-Rotation Structure Across the Jets of 9 Active Galactic NucleiSep 26 2017A number of groups have recently been active in searching for gradients in the ob- served Faraday rotation measure (RM) across jets of Active Galactic Nuclei (AGNs) on various scales and estimating their reliability. Such RM structures provide direct ... More
Trigger Mechanism of Solar Subflares in a Braided Coronal Magnetic StructureOct 16 2014Fine-scale braiding of coronal magnetic loops by continuous footpoint motions may power coronal heating via nanoflares, which are spontaneous fine-scale bursts of internal reconnection. An initial nanoflare may trigger an avalanche of reconnection of ... More
New Evidence that Magnetoconvection Drives Solar-Stellar Coronal HeatingJun 25 2017How magnetic energy is injected and released in the solar corona, keeping it heated to several million degrees, remains elusive. Coronal heating generally increases with increasing magnetic field strength. From comparison of a non-linear force-free model ... More
Transition-Region/Coronal Signatures and Magnetic Setting of Sunspot Penumbral Jets: {\it Hinode} (SOT/FG), Hi-C and {\it SDO}/AIA ObservationsNov 24 2015Penumbral microjets (PJs) are transient narrow bright features in the chromosphere of sunspot penumbrae, first characterized by Katsukawa et al (2007) using the \CaII\ H-line filter on {\it Hinode}'s Solar Optical Telescope (SOT). It was proposed that ... More
The Cells Out of Sample (COOS) dataset and benchmarks for measuring out-of-sample generalization of image classifiersJun 17 2019Understanding if classifiers generalize to out-of-sample datasets is a central problem in machine learning. Microscopy images provide a standardized way to measure the generalization capacity of image classifiers, as we can image the same classes of objects ... More
Determining nonsmooth first order terms from partial boundary measurementsSep 05 2006We extend results of Dos Santos Ferreira-Kenig-Sjoestrand-Uhlmann (math.AP/0601466) to less smooth coefficients, and we show that measurements on part of the boundary for the magnetic Schroedinger operator determine uniquely the magnetic field related ... More
Additive Spanners and Distance Oracles in Quadratic TimeApr 14 2017Let $G$ be an unweighted, undirected graph. An additive $k$-spanner of $G$ is a subgraph $H$ that approximates all distances between pairs of nodes up to an additive error of $+k$, that is, it satisfies $d_H(u,v) \le d_G(u,v)+k$ for all nodes $u,v$, where ... More
Sparsity prior for electrical impedance tomography with partial dataMay 26 2014Dec 22 2014This paper focuses on prior information for improved sparsity reconstruction in electrical impedance tomography with partial data, i.e. data measured only on subsets of the boundary. Sparsity is enforced using an $\ell_1$ norm of the basis coefficients ... More
Reconstruction of less regular conductivities in the planeOct 26 2001We study the inverse conductivity problem of how to reconstruct an isotropic electrical conductivity distribution $\gamma$ in an object from static electrical measurements on the boundary of the object. We give an exact reconstruction algorithm for the ... More
A Kuenneth theorem for configuration spacesOct 04 2018We construct a spectral sequence converging to the homology of the ordered configuration spaces of a product of parallelizable manifolds. To identify the second page of this spectral sequence, we introduce a version of the Boardman--Vogt tensor product ... More
3D Reconstruction for Partial Data Electrical Impedance Tomography Using a Sparsity PriorDec 19 2014In electrical impedance tomography the electrical conductivity inside a physical body is computed from electro-static boundary measurements. The focus of this paper is to extend recent result for the 2D problem to 3D. Prior information about the sparsity ... More
Distinguishability revisited: depth dependent bounds on reconstruction quality in electrical impedance tomographyFeb 11 2016Jan 26 2017The reconstruction problem in electrical impedance tomography is highly ill-posed, and it is often observed numerically that reconstructions have poor resolution far away from the measurement boundary but better resolution near the measurement boundary. ... More
The Chandra Source CatalogMay 25 2010The Chandra Source Catalog (CSC) is a general purpose virtual X-ray astrophysics facility that provides access to a carefully selected set of generally useful quantities for individual X-ray sources, and is designed to satisfy the needs of a broad-based ... More
Signatures of the non-Maxwellian $κ$-distributions in optically thin line spectra. II. Synthetic Fe XVII--XVIII X-ray coronal spectra and predictions for the Marshall Grazing-Incidence X-ray Spectrometer (MaGIXS)May 24 2019We investigated the possibility of diagnosing the degree of departure from the Maxwellian distribution using the Fe XVII - Fe XVIII spectra originating in plasmas in collisional ionization equilibrium, such as in the cores of solar active regions or microflares. ... More