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Results for "Alexandros Gaitanidis"

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Spontaneous Radiofrequency Emission from Electron Spins within Drosophila: a preliminary report on a novel biological signalJul 10 2019Using simple radio frequency (RF) instrumentation, we detect spontaneous RF emission from Drosophila immersed in a magnetic field within a waveguide or a shielded RF resonator. Remarkably, the RF emissions are abolished by chloroform anesthesia, suggesting ... More
On the Ground State of the Supersymmetric Five-braneMar 06 1997We examine if there exists a zero-energy supersymmetric ground state for the fundamental five-brane. Looking for an $SO(6)\times SO(2)$- invariant ground state, we construct, in the light-cone gauge, perturbatively a Nicolai map up to third order in the ... More
N=2 Heterotic Stringy Cosmic StringsNov 14 1996We construct solitonic string solutions of N=2 four-dimensional heterotic models of rank three, four and five. These finite energy configurations have constant dilaton while the moduli fields vary over space-time with jumps at the location of the string ... More
Type IIA/IIB string duality for targets with abelian isometriesFeb 12 1996We examine T-duality transformations for supersymmetric strings with target space geometry with compact abelian isometries. We consider the partition function of these models and we show that although T-duality is not a symmetry, due to an anomaly, it ... More
A Stable Manifold MCMC Method for High DimensionsMar 30 2014We combine two important recent advancements of MCMC algorithms: first, methods utilizing the intrinsic manifold structure of the parameter space; then, algorithms effective for targets in infinite-dimensions with the critical property that their mixing ... More
Helically Decomposed TurbulenceJun 08 2016A decomposition of the energy and helicity fluxes in a turbulent hydrodynamic flow is proposed. The decomposition is based on the projection of the flow to a helical basis that allows to investigate separately the role of interactions among modes of different ... More
Finite Topology on Shapes without PointsFeb 05 2019This paper develops finite topology on shapes formed with elements of the algebras $U_i$, for $i$ > 0. In traditional branches of topology, "shapes" are considered as abstract/immaterial objects, as subsets of an ambient space (e.g. Euclidean space) from ... More
D-Instanton Corrections as (p,q)-String Effects and Non-Renormalization TheoremsDec 16 1997Mar 19 1998We discuss higher derivative interactions in the type IIB superstring in ten dimensions. From the fundamental string point of view, the non-perturbative corrections are due to D-instantons. We argue that they can alternatively be understood as arising ... More
Estimate of the truncation error of a finite volume discretisation of the Navier-Stokes equations on colocated gridsAug 11 2015A methodology is proposed for the calculation of the truncation error of finite volume discretisations of the incompressible Navier-Stokes equations on colocated grids. The truncation error is estimated by restricting the solution obtained on a given ... More
Self-organisation and non-linear dynamics in driven magnetohydrodynamic turbulent flowsJun 11 2014Magnetohydrodynamic turbulent flows driven by random mechanical and electromagnetic external forces of zero helicities are investigated by means of direct numerical simulations. It is shown that despite the absence of helicities in the forcing, the system ... More
The origins of $k^{-2}$ spectrum in the decaying Taylor-Green magnetohydrodynamic turbulent flowsJun 06 2013We investigate the origins of $k^{-2}$ spectrum in a decaying Taylor-Green magnetohydrodynamic flow with zero large scale magnetic flux that was reported in Lee et al. (2010). A possible candidate for this scaling exponent has been the weak turbulence ... More
Ab initio and phenomenological studies of the static response of neutron matterAug 11 2016We investigate the problem of periodically modulated strongly interacting neutron matter. We carry out ab initio non-perturbative auxiliary-field diffusion Monte Carlo calculations using an external sinusoidal potential in addition to phenomenological ... More
Optimization for Large-Scale Machine Learning with Distributed Features and ObservationsOct 31 2016As the size of modern data sets exceeds the disk and memory capacities of a single computer, machine learning practitioners have resorted to parallel and distributed computing. Given that optimization is one of the pillars of machine learning and predictive ... More
Terrestrial and Astrophysical Superfluidity: Cold Atoms and Neutron MatterSep 22 2011After a brief historical overview of superfluidity in connection with neutron matter and cold fermionic atoms, we discuss the commonalities between these two systems as well as their relevance to the physics of neutron star crusts. We then present the ... More
Optimization for Large-Scale Machine Learning with Distributed Features and ObservationsOct 31 2016Apr 15 2017As the size of modern data sets exceeds the disk and memory capacities of a single computer, machine learning practitioners have resorted to parallel and distributed computing. Given that optimization is one of the pillars of machine learning and predictive ... More
An Abstract View on the De-anonymization ProcessFeb 26 2019Over the recent years, the availability of datasets containing personal, but anonymized information has been continuously increasing. Extensive research has revealed that such datasets are vulnerable to privacy breaches: being able to reveal sensitive ... More
A Metric-learning based framework for Support Vector Machines and Multiple Kernel LearningSep 16 2013Most metric learning algorithms, as well as Fisher's Discriminant Analysis (FDA), optimize some cost function of different measures of within-and between-class distances. On the other hand, Support Vector Machines(SVMs) and several Multiple Kernel Learning ... More
Unbalanced low-density neutron matterFeb 11 2013We consider polarized neutron matter at low densities. We have performed Diffusion Monte Carlo simulations for normal neutron matter with different population numbers for each species. We analyze the competition between different phases in the grand canonical ... More
Condensates in rotating turbulent flowsJul 12 2017Using a large number of numerical simulations we examine the steady state of rotating turbulent flows in triple periodic domains, varying the Rossby number $Ro$ (that measures the inverse rotation rate) and the Reynolds number $Re$ (that measures the ... More
The Infinite Gauss-Jordan Elimination on Row-Finite ω x ω\ MatricesJan 13 2012The Gauss-Jordan elimination algorithm is extended to reduce a row-finite $\omega\times\omega$ matrix to lower row-reduced form, founded on a strategy of rightmost pivot elements. Such reduced matrix form preserves row equivalence, unlike the dominant ... More
Using parallelism techniques to improve sequential and multi-core sorting performanceAug 30 2016We propose new sequential sorting operations by adapting techniques and methods used for designing parallel sorting algorithms. Although the norm is to parallelize a sequential algorithm to improve performance, we adapt a contrarian approach: we employ ... More
Exact uniform sampling over catalan structuresMar 11 2018We present a new framework for creating elegant algorithms for exact uniform sampling of important Catalan structures, such as triangulations of convex polygons, Dyck words, monotonic lattice paths and mountain ranges. Along with sampling, we obtain optimal ... More
Gravitational leptogenesis in Natural InflationAug 26 2017Nov 25 2017We compute the gravitational leptogenesis generated from the parity-violating gravitational waves sourced by an abelian gauge field coupled to a pseudo-scalar inflation. We show that, once the CMB bound on the tensor-to-scalar ratio is enforced, the lepton ... More
ReHub. Extending Hub Labels for Reverse k-Nearest Neighbor Queries on Large-Scale networksApr 07 2015Jul 10 2015Quite recently, the algorithmic community has focused on solving multiple shortest-path query problems beyond simple vertex-to-vertex queries, especially in the context of road networks. Unfortunately, this research cannot be generalized for large-scale ... More
Symmetry breaking and universality of decaying MHD Taylor-Green flowsOct 02 2013We investigate the evolution and stability of a decaying magnetohydrodynamic (MHD) Taylor-Green flow. The chosen flow has been shown to result in a steep total energy spectrum with power law behaviour $k^{-2}$. We investigate the symmetry breaking of ... More
Dark Matter from a Classically Scale-Invariant $SU(3)_X$Jul 04 2016Oct 06 2016In this work we study a classically scale-invariant extension of the Standard Model in which the dark matter and electroweak scales are generated through the Coleman-Weinberg mechanism. The extra $SU(3)_X$ gauge factor gets completely broken by the vacuum ... More
Low-density neutron matterNov 19 2009Feb 18 2010The properties of low-density neutron matter are important for the understanding of neutron star crusts and the exterior of large neutron-rich nuclei. We examine various properties of dilute neutron matter using quantum Monte Carlo methods, with s- and ... More
Method to measure efficiently rare fluctuations of turbulence intensity for turbulent-laminar transitions in pipe flowsJul 16 2017Dec 15 2017The fluctuations of turbulence intensity in a pipe flow around the critical Reynolds number is difficult to study but important because they are related to turbulent-laminar transitions. We here propose a rare-event sampling method to study such fluctuations ... More
Competing phases in spin ladders with ring exchange and frustrationNov 30 2016The ground state properties of spin-1/2 ladders are studied, emphasizing the role of frustration and ring exchange coupling. We present a unified field theory for ladders with general coupling constants and geometry. Rich phase diagrams can be deduced ... More
Finite volume adaptive solutions using SIMPLE as smootherAug 13 2015This paper describes a new multilevel procedure that can solve the discrete Navier-Stokes system arising from finite volume discretizations on composite grids, which may consist of more than one level. SIMPLE is used and tested as the smoother, but the ... More
Relationship-aware sequential pattern miningDec 21 2012Relationship-aware sequential pattern mining is the problem of mining frequent patterns in sequences in which the events of a sequence are mutually related by one or more concepts from some respective hierarchical taxonomies, based on the type of the ... More
Dark matter and neutrino masses from a scale-invariant multi-Higgs portalAug 12 2015Feb 02 2016We consider a classically scale invariant version of the Standard Model, extended by an extra dark $SU(2)_X$ gauge group. Apart from the dark gauge bosons and a dark scalar doublet which is coupled to the Standard Model Higgs through a portal coupling, ... More
Dark matter and neutrino masses from a classically scale-invariant multi-Higgs portalMar 28 2016We present a classically scale-invariant model where the dark matter, neutrino and electroweak mass scales are dynamically generated from dimensionless couplings. The Standard Model gauge sector is extended by a dark $SU(2)_X$ gauge symmetry that is completely ... More
The Casimir effect in string theoryDec 27 2018We discuss the Casimir effect in heterotic string theory. This is done by considering a Z_2 twist acting on one external compact direction and three internal coordinates. The hyperplanes fixed by the orbifold generator G realize the two infinite parallel ... More
The Solution of Row-Finite Linear Systems with the Infinite Gauss-Jordan Elimination The Case of Linear Difference Equations with Variable CoefficientsMar 11 2014The construction of the general solution sequence of row-finite linear systems is accomplished by implementing -ad infinitum- the Gauss-Jordan algorithm under a rightmost pivot elimination strategy. The algorithm generates a basis (finite or Schauder) ... More
Flavor: A Language for Media RepresentationJan 07 2003Flavor (Formal Language for Audio-Visual Object Representation) has been created as a language for describing coded multimedia bitstreams in a formal way so that the code for reading and writing bitstreams can be automatically generated. It is an extension ... More
Structures and dynamics of small scales in decaying magnetohydrodynamic turbulenceApr 02 2013The topological and dynamical features of small scales are studied in the context of decaying magnetohydrodynamic turbulent flows using direct numerical simulations. Joint probability density functions (PDFs) of the invariants of gradient quantities related ... More
Infinite-dimensional algebras in dimensionally reduced string theoryJun 30 1995We examine 4-dimensional string backgrounds compactified over a two torus. There exist two alternative effective Lagrangians containing each two $SL(2)/U(1)$ sigma-models. Two of these sigma-models are the complex and the K\"ahler structures on the torus. ... More
Community Cloud ComputingJul 15 2009Oct 12 2009Cloud Computing is rising fast, with its data centres growing at an unprecedented rate. However, this has come with concerns over privacy, efficiency at the expense of resilience, and environmental sustainability, because of the dependence on Cloud vendors ... More
Polynomial inequalities on the Hamming cubeFeb 06 2019Let $(X,\|\cdot\|_X)$ be a Banach space. The purpose of this article is to systematically investigate dimension independent properties of vector valued functions $f:\{-1,1\}^n\to X$ on the Hamming cube whose spectrum is bounded above or below. Our proofs ... More
The fate of alpha dynamos at large $Rm$Jul 25 2016At the heart of today's solar magnetic field evolution models lies the alpha dynamo description. In this work, we investigate the fate of alpha-dynamos as the magnetic Reynolds number $Rm$ is increased. Using Floquet theory, we are able to precisely quantify ... More
Phase separation in low-density neutron matterNov 01 2011Jan 17 2012Low-density neutron matter has been studied extensively for many decades, with a view to better understanding the properties of neutron-star crusts and neutron-rich nuclei. Neutron matter is beyond experimental control, but in the past decade it has become ... More
Static Response of Neutron MatterOct 21 2015Apr 12 2016We generalize the problem of strongly interacting neutron matter by adding a periodic external modulation. This allows us to study from first principles a neutron system that is extended and inhomogeneous, with connections to the physics of both neutron-star ... More
Thermal Transport in a one-dimensional Z$_{2}$ Spin LiquidMay 30 2016We study the dynamical thermal conductivity of the Kitaev spin model on a two-leg ladder. In contrast to conventional integrable one-dimensional spin systems, we show that heat transport is completely dissipative. This is a direct consequence of fractionalization ... More
The Lorentz force effect on the On-Off dynamo intermittencySep 29 2007An investigation of the dynamo instability close to the threshold produced by an ABC forced flow is presented. We focus on the on-off intermittency behavior of the dynamo and the counter-effect of the Lorentz force in the non-linear stage of the dynamo. ... More
Understanding human-human interactions: a surveyJul 31 2018Many videos depict people, and it is their interactions that inform us of their activities, relation to one another and the cultural and social setting. With advances in human action recognition, researchers have begun to address the automated recognition ... More
The signature of initial conditions on magnetohydrodynamic turbulenceDec 27 2013We demonstrate that special correlations in the initial conditions of freely evolving, homogeneous magnetohydrodynamic (MHD) turbulence can lead to the formation of enormous current sheets. These coherent structures are observed at the peak of the energy ... More
Digital Ecosystems in the Clouds: Towards Community Cloud ComputingMar 04 2009Oct 05 2009Cloud Computing is rising fast, with its data centres growing at an unprecedented rate. However, this has come with concerns of privacy, efficiency at the expense of resilience, and environmental sustainability, because of the dependence on Cloud vendors ... More
Embedding Properties of sets with finite box-counting dimensionNov 09 2018In this paper we study the regularity of embeddings of finite--dimensional subsets of Banach spaces into Euclidean spaces. In 1999, Hunt and Kaloshin [Nonlinearity 12 1263-1275] introduced the thickness exponent and proved an embedding theorem for subsets ... More
Strongly paired fermions: Cold atoms and neutron matterNov 19 2007Mar 12 2008Experiments with cold Fermi atoms can be tuned to probe strongly interacting fluids that are very similar to the low-density neutron matter found in the crusts of neutron stars. In contrast to traditional superfluids and superconductors, matter in this ... More
Getting deep recommenders fit: Bloom embeddings for sparse binary input/output networksJun 13 2017Recommendation algorithms that incorporate techniques from deep learning are becoming increasingly popular. Due to the structure of the data coming from recommendation domains (i.e., one-hot-encoded vectors of item preferences), these algorithms tend ... More
Ab initio and phenomenological studies of the static response of neutron matterAug 11 2016Apr 07 2017We investigate the problem of periodically modulated strongly interacting neutron matter. We carry out ab initio non-perturbative auxiliary-field diffusion Monte Carlo calculations using an external sinusoidal potential in addition to phenomenological ... More
Bounding the scalar dissipation scale for mixing flows in the presence of sourcesMar 25 2011Sep 29 2011We investigate the mixing properties of scalars stirred by spatially smooth, divergence-free flows and maintained by a steady source-sink distribution. We focus on the spatial variation of the scalar field, described by the {\it dissipation wavenumber}, ... More
No input symbol should occur more frequently than 1-1/eJan 31 2012Consider any discrete memoryless channel (DMC) with arbitrarily but finite input and output alphabets X, Y respectively. Then, for any capacity achieving input distribution all symbols occur less frequently than 1-1/e$. That is, \[ \max\limits_{x \in ... More
Complete bases of canonical polynomials and the full recursive formulation of the spectral-tau methodNov 28 2016A decomposition of a higher order linear differential operator with polynomial coefficients into a direct sum of two factor operators is obtained. This leads to a lower echelon matrix representation for operators of the above mentioned type arising from ... More
Effective 3-Body Interaction for Mean-Field and Density-Functional TheoryAug 24 2010Nov 17 2010Density functionals for nuclei usually include an effective 3-body interaction that depends on a fractional power of the density. Using insights from the many-body theory of the low-density two-component Fermi gas, we consider a new, nonlocal, form for ... More
The Hairy Ball Problem is PPAD-CompleteFeb 20 2019The Hairy Ball Theorem states that every continuous tangent vector field on an even-dimensional sphere must have a zero. We prove that the associated computational problem of computing an approximate zero is PPAD-complete. We also give a FIXP-hardness ... More
Fast inference in generalized linear models via expected log-likelihoodsMay 24 2013Generalized linear models play an essential role in a wide variety of statistical applications. This paper discusses an approximation of the likelihood in these models that can greatly facilitate computation. The basic idea is to replace a sum that appears ... More
The energy distribution of electrons in radio jetsJun 16 2017Black-hole and neutron-star X-ray binaries exhibit compact radio jets, when they are in the so called quiescent, hard, or hard intermediate states. The radio spectrum in these states is flat to slightly inverted. It is widely accepted that the energy ... More
One-dimensional Deep Image Prior for Time Series Inverse ProblemsApr 18 2019We extend the Deep Image Prior (DIP) framework to one-dimensional signals. DIP is using a randomly initialized convolutional neural network (CNN) to solve linear inverse problems by optimizing over weights to fit the observed measurements. Our main finding ... More
Condensates in thin-layer turbulenceAug 01 2018Mar 13 2019We examine the steady state of turbulent flows in thin layers using direct numerical simulations. It is shown that when the layer thickness is smaller than a critical height, an inverse cascade arises which leads to the formation of a steady state condensate ... More
$O(d,d)$ Symmetry in Quantum CosmologyFeb 15 1996Feb 16 1996We analyze the quantum cosmology of one--loop string effective models which exhibit an $O(d,d)$ symmetry. It is shown that due to the large symmetry of these models the Wheeler--de Witt equation can completely be solved. As a result, we find a basis of ... More
Condensates in thin-layer turbulenceAug 01 2018Oct 25 2018We examine the steady state of turbulent flows in thin layers using direct numerical simulations. It is shown that when the layer thickness is smaller than a critical height, an inverse cascade arises which leads to the formation of a steady state condensate ... More
Diffusion of Point Defects in Two-Dimensional Colloidal CrystalsMar 11 2001We report the first study of the dynamics of point defects, mono and di-vacancies, in a confined 2-D colloidal crystal in real space and time using digital video microscopy. The defects are introduced by manipulating individual particles with optical ... More
Moment ideals of local Dirac mixturesSep 26 2018In this paper we study ideals arising from moments of local Dirac measures and their mixtures. We provide generators for the case of first order local Diracs and explain how to obtain the moment ideal of the Pareto distribution from them. We then use ... More
Exact simulation of diffusionsFeb 23 2006We describe a new, surprisingly simple algorithm, that simulates exact sample paths of a class of stochastic differential equations. It involves rejection sampling and, when applicable, returns the location of the path at a random collection of time instances. ... More
The efficiency of resource allocation mechanisms for budget-constrained usersJul 12 2017Feb 15 2018We study the efficiency of mechanisms for allocating a divisible resource. Given scalar signals submitted by all users, such a mechanism decides the fraction of the resource that each user will receive and a payment that will be collected from her. Users ... More
Bounding Multiple Unicasts through Index Coding and Locally Repairable CodesFeb 17 2014We establish a duality result between linear index coding and Locally Repairable Codes (LRCs). Specifically, we show that a natural extension of LRCs we call Generalized Locally Repairable Codes (GLCRs) are exactly dual to linear index codes. In a GLRC, ... More
Equilibrium Configurations and Energetics of Point Defects in Two-Dimensional Colloidal CrystalsDec 16 2000Dec 20 2000We demonstrate a novel method of introducing point defects (mono and di-vacancies) in a confined mono-layer colloidal crystal by manipulating individual particles with optical tweezers. Digital video microscopy is used to study defect dynamics in real ... More
Energy fluxes in quasi-equilibrium flowsJun 06 2019We examine the relation between the absolute equilibrium state of the spectrally truncated Euler equations (TEE) predicted by Kraichnan (1973) to the forced and dissipated flows of the spectrally truncated Navier-Stokes (TNS) equations. In both of these ... More
Energy and enstrophy dissipation in steady state 2-d turbulenceMay 11 2006Upper bounds on the bulk energy dissipation rate $\epsilon$ and enstrophy dissipation rate $\chi$ are derived for the statistical steady state of body forced two dimensional turbulence in a periodic domain. For a broad class of externally imposed body ... More
Repairable Fountain CodesJan 03 2014We introduce a new family of Fountain codes that are systematic and also have sparse parities. Given an input of $k$ symbols, our codes produce an unbounded number of output symbols, generating each parity independently by linearly combining a logarithmic ... More
Connecting web-based mapping services with scientific data repositories: collaborative curation and retrieval of simulation data via a geospatial interfaceJun 18 2016Sep 21 2016Increasing quantities of scientific data are becoming readily accessible via online repositories such as those provided by Figshare and Zenodo. Geoscientific simulations in particular generate large quantities of data, with several research groups studying ... More
Welfare guarantees for proportional allocationsFeb 14 2014According to the proportional allocation mechanism from the network optimization literature, users compete for a divisible resource -- such as bandwidth -- by submitting bids. The mechanism allocates to each user a fraction of the resource that is proportional ... More
Embedding Properties of sets with finite box-counting dimensionNov 09 2018Apr 10 2019In this paper we study the regularity of embeddings of finite--dimensional subsets of Banach spaces into Euclidean spaces. In 1999, Hunt and Kaloshin [Nonlinearity 12 1263-1275] introduced the thickness exponent and proved an embedding theorem for subsets ... More
The cool side of Lyman Alpha EmittersJul 29 2009Nov 06 2009We extend a previous study of Lyman Alpha Emitters (LAEs) based on hydrodynamical cosmological simulations, by including two physical processes important for LAEs: (a) Lyman Alpha and continuum luminosities produced by cooling of collisionally excited ... More
SALT. A unified framework for all shortest-path query variants on road networksNov 02 2014Although recent scientific output focuses on multiple shortest-path problem definitions for road networks, none of the existing solutions does efficiently answer all different types of SP queries. This work proposes SALT, a novel framework that not only ... More
Existence and uniqueness results for BSDEs with jumps: the whole nine yardsJul 14 2016This paper is devoted to obtaining a wellposedness result for multidimensional BSDEs with possibly unbounded random time horizon and driven by a general martingale in a filtration only assumed to satisfy the usual hypotheses, which in particular may be ... More
Optimal lengthscale for a turbulent dynamoSep 11 2015We demonstrate that there is an optimal forcing length scale for low Prandtl number dynamo flows, that can significantly reduce the required energy injection rate. The investigation is based on simulations of the induction equation in a periodic box of ... More
On the edge of an inverse cascadeJun 16 2014We demonstrate that systems with a parameter-controlled inverse cascade can exhibit critical behavior for which at the critical value of the control parameter the inverse cascade stops. In the vicinity of such a critical point standard phenomenological ... More
Decentralized Erasure Codes for Distributed Networked StorageJun 12 2006We consider the problem of constructing an erasure code for storage over a network when the data sources are distributed. Specifically, we assume that there are n storage nodes with limited memory and k<n sources generating the data. We want a data collector, ... More
On the inverse cascade of magnetic helicitySep 08 2005We study the inverse cascade of magnetic helicity in conducting fluids by investigating the detailed transfer of helicity between different spherical shells in Fourier space in direct numerical simulations of three-dimensional magnetohydrodynamics (MHD). ... More
A finite volume method for the simulation of elastoviscoplastic flows and its application to the lid-driven cavity caseDec 19 2018We propose a Finite Volume Method for the simulation of elastoviscoplastic flows, modelled after the extension to the Herschel-Bulkley model by Saramito [J. Non-Newton. Fluid Mech. 158 (2009) 154-161]. The method is akin to methods for viscoelastic flows. ... More
Auditing for Distributed Storage SystemsMar 08 2012May 12 2014Distributed storage codes have recently received a lot of attention in the community. Independently, another body of work has proposed integrity checking schemes for cloud storage, none of which, however, is customized for coding-based storage or can ... More
Hyperspectral Image Classification and Clutter Detection via Multiple Structural Embeddings and Dimension ReductionsJun 03 2015We present a new and effective approach for Hyperspectral Image (HSI) classification and clutter detection, overcoming a few long-standing challenges presented by HSI data characteristics. Residing in a high-dimensional spectral attribute space, HSI data ... More
"23andMe confirms: I'm super white" -- Analyzing Twitter Discourse On Genetic TestingJan 30 2018Apr 20 2018Recent progress in genomics is bringing genetic testing to the masses. Participatory public initiatives are underway to sequence the genome of millions of volunteers, and a new market is booming with a number of companies like 23andMe and AncestryDNA ... More
Cross-topic distributional semantic representations via unsupervised mappingsApr 11 2019In traditional Distributional Semantic Models (DSMs) the multiple senses of a polysemous word are conflated into a single vector space representation. In this work, we propose a DSM that learns multiple distributional representations of a word based on ... More
Neutron matter at the interface(s): from interactions to ab initio and from there to phenomenologyJun 04 2019Neutron matter is interesting both as an extension of terrestrial nuclear physics and due to its significance for the study of neutron stars. In this work, after some introductory comments on nuclear forces, nuclear ab initio theory, and nuclear phenomenology, ... More
Heat transport in the anisotropic Kitaev spin liquidOct 10 2018We present a study of longitudinal thermal transport in the Kitaev spin model on the honeycomb lattice, focusing on the role of anisotropic exchange to cover both, gapless and gapped phases. Employing a complementary combination of exact diagonalization ... More
Probabilistic Saliency EstimationSep 13 2016Feb 20 2017In this paper, we model the salient object detection problem under a probabilistic framework encoding the boundary connectivity saliency cue and smoothness constraints in an optimization problem. We show that this problem has a closed form global optimum ... More
Distributed Storage Allocations for Optimal DelayJun 14 2011We examine the problem of creating an encoded distributed storage representation of a data object for a network of mobile storage nodes so as to achieve the optimal recovery delay. A source node creates a single data object and disseminates an encoded ... More
ε-Strong simulation of the Brownian pathOct 01 2011Nov 26 2012We present an iterative sampling method which delivers upper and lower bounding processes for the Brownian path. We develop such processes with particular emphasis on being able to unbiasedly simulate them on a personal computer. The dominating processes ... More
The fundamental properties of time varying AR models with non stochastic coefficientsMar 13 2014The paper examines the problem of representing the dynamics of low order autoregressive (AR) models with time varying (TV) coefficients. The existing literature computes the forecasts of the series from a recursion relation. Instead, we provide the linearly ... More
Sparse Logistic Regression Learns All Discrete Pairwise Graphical ModelsOct 28 2018Jun 18 2019We characterize the effectiveness of a classical algorithm for recovering the Markov graph of a general discrete pairwise graphical model from i.i.d. samples. The algorithm is (appropriately regularized) maximum conditional log-likelihood, which involves ... More
The Cry Wolf Effect in Evacuation: a Game-Theoretic ApproachApr 03 2019Apr 12 2019In today's terrorism-prone and security-focused world, evacuation emergencies, drills, and false alarms are becoming more and more common. Compliance to an evacuation order made by an authority in case of emergency can play a key role in the outcome of ... More
Nonlinear perturbations from the coupling of the inflaton to a non-Abelian gauge field, with a focus on Chromo-Natural InflationJun 21 2018Sep 13 2018Several models of inflation employing a triplet of SU(2) vectors with spatially orthogonal vacuum expectation values (VEVs) have been recently proposed. One (tensor) combination $t$ of the vector modes is amplified in some momentum range during inflation. ... More
Fluctuations of electrical conductivity: a new source for astrophysical magnetic fieldsApr 02 2016We consider the generation of magnetic field by the flow of a fluid for which the electrical conductivity is nonuniform. A new amplification mechanism is found which leads to dynamo action for flows much simpler than those considered so far. In particular, ... More
Asymptotic Analysis of Model Selection Criteria for General Hidden Markov ModelsNov 28 2018Jun 05 2019The paper obtains analytical results for the asymptotic properties of Model Selection Criteria -- widely used in practice -- for a general family of hidden Markov models (HMMs), thereby substantially extending the related theory beyond typical i.i.d.-like ... More
Connectivity and equilibrium in random gamesMar 29 2007Nov 12 2012We study how the structure of the interaction graph of a game affects the existence of pure Nash equilibria. In particular, for a fixed interaction graph, we are interested in whether there are pure Nash equilibria arising when random utility tables are ... More
Non-Abelian T-duality for open stringsOct 09 1996Dec 19 1996In the first part of the talk we discuss T-duality for a free boson on a world sheet with boundary in a setting suitable for the generalization to non-trivial backgrounds. The gauging method as well as the canonical transformation are considered. In both ... More