Results for "Yonatan Dubi"

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Transport Through Self-Assembled Monolayer Molecular Junctions: Role of In-Plane DephasingJul 20 2014Self-assembled-monolayer (SAM) molecular junctions (MJs) constitute a promising building block candidate for future molecular electronic devices. Transport properties of SAM-MJs are usually calculate using either the phenomenological Simmons model, or ... More
The effect of fluctuations - thermal and otherwise - on the temperature dependence of thermopower in aromatic chain single-molecule junctionsMar 03 2013We report a theoretical study of the thermopower of single-molecule junctions, with focus on phenyl-based molecular junctions. In contrast to prior studies, thermal fluctuations of the torsional angle between the phenyl rings and variations in the position ... More
Dynamical coupling and negative differential resistance from interactions across the molecule-electrode interface in molecular junctionsSep 11 2013Negative differential resistance - a decrease in current with increasing bias voltage - is a counter-intuitive effect that is observed in various molecular junctions. Here, we present a novel mechanism that may be responsible for such an effect, based ... More
Quantum Hall Criticality, Superconductor-Insulator Transition and Quantum PercolationJun 01 2004A model consisting of a mixture of superconducting and quantum links is proposed to describe the integer quantum Hall transition. The quantum links correspond to tunneling of electrons between trajectories trapped in adjacent potential valleys, while ... More
Interplay between Dephasing and Geometry and Directed Heat Flow in Exciton Transfer ComplexesOct 11 2015The striking efficiency of energy transfer in natural photosynthetic systems and the recent evidence of long-lived quantum coherence in biological light harvesting complexes has triggered much excitement, due to the evocative possibility that these systems ... More
Origin of thermoelectric response fluctuations in single-molecule junctionsNov 20 2012The thermoelectric response of molecular junctions exhibits large fluctuations, as observed in recent experiments [e.g. Malen J. A. {\sl et al.}, Nano Lett. {\bf 10}, 3406 (2009)]. These were attributed to fluctuations in the energy alignment between ... More
Pair correlations and the survival of superconductivity in and around a super-conducting impurityMay 25 2006Feb 15 2007The problem of the survival of superconductivity in a small super-conducting grain placed in a metal substrate is addressed. For this aim the pair correlations and super-conducting gap around and inside a negative-U impurity in one and two dimensions ... More
Microwave-mediated heat transport through a quantum dotFeb 06 2012The thermoelectric effect in a quantum dot (QD) attached to two leads in the presence of microwave fields is studied by using the Keldysh nonequilibrium Green function technique. When the microwave is applied only on the QD and in the linear-response ... More
Negative differential conductance in molecular junctions: an overview of experiment and theoryMay 28 2015One of the ultimate goals of molecular electronics is to create technologies that will complement - and eventually supersede - Si-based microelectronics technologies. To reach this goal, electronic properties that mimic at least some of the electrical ... More
Energy flow and thermo-electricity in atomic and molecular junctionsOct 02 2009Oct 15 2010Advances in the fabrication and characterization of nanoscale systems now allow for a deeper understanding of one of the most basic issues in science and technology: the flow of energy at the microscopic level. In this Colloquium we survey recent advances ... More
Eppur si riscalda -- and yet, it (just) heats up: Further Comments on "Quantifying hot carrier and thermal contributions in plasmonic photocatalysis"Jul 10 2019Our Comment [Sivan et al., Science 2019] (as well as its longer version [Dubi, Un, & Sivan, ArXiv 2019], and the supporting theoretical studies [Dubi and Sivan, ArXiv 2018]) on recent attempts to distinguish thermal and non-thermal ("hot carrier") contributions ... More
Enhanced Thermoelectric Performance in Hybrid Nanoparticle--Single Molecule JunctionsJun 06 2015It was recently suggested that molecular junctions would be excellent elements for efficient and high-power thermoelectric energy conversion devices. However, experimental measurements of thermoelectric conversion in molecular junctions have indicated ... More
Dimer mean-field model for the Ising spin glassDec 15 2009A dimer mean-field model for the Ising spin-glass is presented. Despite its simplicity it captures some of the essential features of the spin-glass physics. The distribution of the single-spin magnetization is determined from a self-consistent integral ... More
Maintaining the local temperature below the critical value in thermally out of equilibrium superconducting wiresJul 15 2009A generalized theory of open quantum systems combined with mean-field theory is used to study a superconducting wire in contact with thermal baths at different temperatures. It is shown that, depending on the temperature of the colder bath, the temperature ... More
Thermal effects - an alternative mechanism for plasmonic-assisted photo-catalysisFeb 08 2019Recent experiments claimed that the enhancement of catalytic reaction rates occurs via the reduction of activation barriers driven by non-equilibrium ("hot") electrons in plasmonic metal nano-particles. These experiments place plasmonic photo-catalysis ... More
Distribution of twisted Kloosterman sums modulo prime powersJan 27 2008Mar 31 2008In this note we study Kloosterman sums twisted by a multiplicative characters modulo a prime power. We show, by an elementary calculation, that these sums become equidistributed on the real line with respect to a suitable measure.
A unifying model for several two-dimensional phase transitionsSep 30 2004Oct 01 2004A relatively simple and physically transparent model based on quantum percolation and dephasing is employed to construct a global phase diagram which encodes and unifies the critical physics of the quantum Hall, "two-dimensional metal-insulator", classical ... More
The Molecular Photo-Cell: Quantum Transport and Energy Conversion at Strong Non-EquilibriumJun 18 2014Jan 26 2015Non-equilibrium transport properties and energy conversion performance of a molecular photo-voltaic cell are analyzed using the Lindblad master equation within the open quantum systems approach. The method allows us to calculate the dynamics of a system ... More
Nature of the superconductor-insulator transition in disordered superconductorsOct 29 2007As a superconducting thin film becomes disordered and subject to an increasing magnetic field, a point is reached when it undergoes a transition from a superconducting to an insulating state. We use the Bogoliubov-De-Gennes equations and a novel Monte-Carlo ... More
Theory of Magneto-resistance of Disordered Superconducting FilmsMay 16 2005Recent experimental studies of magneto-resistance in disordered superconducting thin films reveal a huge peak (about 5 orders of magnitude). While it may be expected that magnetic field destroys superconductivity, leading to an enhanced resistance, attenuation ... More
Approximation of points in the plane by generic lattice orbitsJun 28 2016We give upper and lower bounds for Diophantine exponents measuring how well a point in the plane can be approximated by points in the orbit of a lattice $\Gamma<\mathrm{SL}_2(\mathbb{R})$ acting linearly on $\mathbb{R}^2$. Our method gives bounds that ... More
Hybrid trace formula for a non-uniform irreducible lattice in $\PSL_2(\bbR)^n$Aug 29 2012Dec 05 2012In a series of lectures Selberg introduced a trace formula on the space of hybrid Maass-modular forms of an irreducible uniform lattice in $\PSL_2(\bbR)^n$. In this paper we derive the analogous formula for a non-uniform lattice and use it to study the ... More
A refinement of strong multiplicity one for spectra of hyperbolic manifoldsAug 15 2011Sep 09 2011Let $\calM_1$ and $\calM_2$ denote two compact hyperbolic manifolds. Assume that the multiplicities of eigenvalues of the Laplacian acting on $L^2(\calM_1)$ and $L^2(\calM_2)$ (respectively, multiplicities of lengths of closed geodesics in $\calM_1$ and ... More
A Uniform Strong Spectral Gap for Congruence Covers of a compact quotient of PSL(2,R)^dFeb 18 2010May 19 2010The existence of a strong spectral gap for lattices in semi-simple Lie groups is crucial in many applications. In particular, for arithmetic lattices it is useful to have bounds for the strong spectral gap that are uniform in the family of congruence ... More
Large Tunable Thermophase in Superconductor -- Quantum Dot -- Superconductor Josephson JunctionsDec 28 2015Oct 30 2016In spite of extended efforts, detecting thermoelectric effects in superconductors have proven to be a challenging task, due to the inherent superconducting particle-hole symmetry. Here we present a theoretical study of an experimentally attainable Superconductor ... More
On the Pair Correlation Density for Hyperbolic AnglesAug 03 2013May 07 2014Let $\Gamma< \mathrm{PSL}_2(\mathbb{R})$ be a lattice and $\omega\in \mathbb{H}$ a point in the upper half plane. We prove the existence and give an explicit formula for the pair correlation density function for the set of angles between geodesic rays ... More
Tunable Thermal Switching via DNA-Based Nano DevicesJul 23 2012Dec 28 2012DNA has a well-defined structural transition -- the denaturation of its double-stranded form into two single strands -- that strongly affects its thermal transport properties. We show that, according to a widely implemented model for DNA denaturation, ... More
Charge density wave in hidden order state of URu$_2$Si$_2$Oct 05 2010We argue that the hidden order state in URu$_2$Si$_2$ will induce a charge density wave. The modulation vector of the charge density wave will be twice that of the hidden order state, $Q_{CDW} = 2Q_{HO}$. To illustrate how the charge density wave arises ... More
Driving denaturation: Nanoscale thermal transport as a probe of DNA meltingDec 30 2010May 18 2011DNA denaturation has long been a subject of intense study due to its relationship to DNA transcription and its fundamental importance as a nonlinear, structural transition. Many aspects of this phenomenon, however, remain poorly understood. Existing models ... More
Exponents for the Equidistribution of Shears and ApplicationsFeb 26 2018In previous work, the authors introduced "soft" methods to prove the effective (i.e. with power savings error) equidistribution of "shears" in cusped hyperbolic surfaces. In this paper, we study the same problem but now allow full use of the spectral ... More
Exponential mixing and shrinking targets for geodesic flow on geometrically finite hyperbolic manifoldsDec 13 2018Let $\mathcal{M}=\Gamma\backslash \mathbb{H}^n$ be a geometrically finite hyperbolic manifold, which is either convex cocompact or of critical exponent $\delta$ strictly bigger than $(n-1)/2$. We present a very general theorem on the shrinking target ... More
Values of random polynomials in shrinking targetsDec 11 2018Relying on the classical second moment formula of Rogers we give an effective asymptotic formula for the number of integer vectors $v$ in a ball of radius $t$, with value $Q(v)$ in a shrinking interval of size $t^{-\kappa}$, that is valid for almost all ... More
Shrinking targets problems for flows on homogeneous spacesAug 29 2017Sep 21 2017We study shrinking targets problems for discrete time flows on a homogenous space $\Gamma\backslash G$ with $G$ a semisimple group and $\Gamma$ an irreducible lattice. Our results apply to both diagonalizable and unipotent flows, and apply to very general ... More
The second moment of the Siegel transform in the space of symplectic latticesFeb 26 2018Using results from spectral theory of Eisenstein series, we prove a formula for the second moment of the Siegel transform when averaged over the subspace of symplectic lattices. This generalizes the classical formula of Rogers for the second moment in ... More
Quasi-unital $\infty$-CategoriesSep 30 2012Sep 13 2013Inspired by Lurie's theory of quasi-unital algebras we prove an analogous result for $\infty$-categories. In particular, we show that the unital structure of an $\infty$-category can be uniquely recovered from the underlying non-unital structure once ... More
Integral points on conic log K3 surfacesNov 16 2015Adapting a powerful method of Swinnerton-Dyer, we give explicit sufficient conditions for the existence of integral points on certain schemes which are fibered into affine conics. This includes, in particular, cases where the scheme is geometrically a ... More
Tales of HoffmanJul 07 2004Jul 29 2004Hofmman's bound on the chromatic number of a graph states that $\chi \geq 1 - \frac {\lambda_1} {\lambda_n}$. Here we show that the same bound, or slight modifications of it, hold for several graph parameters related to the chromatic number: the vector ... More
Quaternionic Wiener Algebras, Factorization and ApplicationsMay 26 2016Dec 22 2016We define an almost periodic extension of the Wiener algebras in the quaternionic setting and prove a Wiener-Levy type theorem for it, as well as extending the theorem to the matrix-valued case. We prove a Wiener-Hopf factorization theorem for the quaternionic ... More
The Cobordism Hypothesis in Dimension 1Sep 30 2012In 2009 Lurie published an expository article outlining a proof for a higher version of the cobordism hypothesis conjectured by Baez and Dolan in 1995. In this note we give a proof for the 1-dimensional case of this conjecture. The proof follows most ... More
Intergenerational mobility measures in a bivariate normal modelJun 23 2017We model the joint log-income distribution of parents and children and derive analytic expressions for canonical relative and absolute intergenerational mobility measures. We find that both types of mobility measures can be expressed as a function of ... More
Lax limits of model categoriesFeb 13 2019For a diagram of simplicial combinatorial model categories, we show that the associated lax limit, endowed with the projective model structure, is a presentation of the lax limit of the underlying $\infty$-categories. Our approach can also allow for the ... More
Mean Dimension & Jaworski-type TheoremsAug 26 2012Oct 20 2015According to the celebrated Jaworski Theorem, a finite dimensional aperiodic dynamical system $(X,T)$ embeds in the $1$-dimensional cubical shift $([0,1]^{\mathbb{Z}},shift)$. If $X$ admits periodic points (still assuming $\dim(X)<\infty$) then we show ... More
Dynamical Embedding in Cubical Shifts & the Topological Rokhlin and Small Boundary PropertiesJan 25 2013Nov 20 2013According to a conjecture of Lindenstrauss and Tsukamoto, a topological dynamical system $(X,T)$ is embeddable in the $d$-cubical shift $(([0,1]^{d})^{\mathbb{Z}},\ shift)$ if both its mean dimension and periodic dimension are strictly bounded by $\frac{d}{2}$. ... More
Unbinned halo-independent methods for emerging dark matter signalsNov 17 2014Halo-independent methods for analyzing direct detection experiments can provide robust results while making no assumptions about the dark matter halo in our galaxy. We extend existing methods to the case of unbinned data, which is especially well suited ... More
The Section Conjecture for Graphs and Conical CurvesApr 26 2013In this paper we formulate and prove a combinatorial version of the section conjecture for finite groups acting on finite graphs. We apply this result to the study of rational points and show that finite descent is the only obstruction to the Hasse principle ... More
Quaternionic Wiener Algebras, Factorization and ApplicationsMay 26 2016May 27 2016We define an almost periodic extension of the Wiener algebras in the quaternionic setting and prove a Wiener-Levy type theorem for it, as well as extending the theorem to the matrix-valued case. We prove a Wiener-Hopf factorization theorem for the quaternionic ... More
Ambidexterity and the universality of finite spansMar 28 2017Jan 28 2019Pursuing the notions of ambidexterity and higher semiadditivity as developed by Hopkins and Lurie, we prove that the span $\infty$-category of $m$-finite spaces is the free $m$-semiadditive $\infty$-category generated by a single object. Passing to presentable ... More
Integral points on conic log K3 surfacesNov 16 2015Mar 15 2017Adapting a powerful method of Swinnerton-Dyer, we give explicit sufficient conditions for the existence of integral points on certain schemes which are fibered into affine conics. This includes, in particular, cases where the scheme is geometrically a ... More
The evolution of microRNA-regulation in duplicated genes facilitates expression divergenceFeb 26 2008Background: The evolution of microRNA regulation in metazoans is a mysterious process: MicroRNA sequences are highly conserved among distal organisms, but on the other hand, there is no evident conservation of their targets. Results: We study this extensive ... More
On the functional properties of microRNA-mediated feed forward loopsFeb 23 2008Feb 26 2008Motivation: Recent studies of genomic-scale regulatory networks suggested that a feed-forward loop (FFL) circuitry is a key component of many such networks. This led to a study of the functional properties of different FFL types, where the regulatory ... More
Geometry and arithmetic of certain log K3 surfacesNov 04 2015Let $k$ be a field of characteristic $0$. In this paper we describe a classification of smooth log K3 surfaces $X$ over $k$ whose geometric Picard group is trivial and which can be compactified into del Pezzo surfaces. We show that such an $X$ can always ... More
Takens' embedding theorem with a continuous observableOct 20 2015May 13 2016Let $(X,T)$ be a dynamical system where $X$ is a compact metric space and $T:X\rightarrow X$ is continuous and invertible. Assume the Lebesgue covering dimension of $X$ is $d$. We show that for a generic continuous map $h:X\rightarrow[0,1]$, the $(2d+1)$-delay ... More
Second descent and rational points on Kummer varietiesMar 15 2017A powerful method pioneered by Swinnerton-Dyer allows one to study rational points on pencils of curves of genus 1 by combining the fibration method with a sophisticated form of descent. A variant of this method, first used by Skorobogatov and Swinnerton-Dyer ... More
Relaxation times in an open interacting two-qubit systemSep 18 2008In a two-qubit system the coupling with an environment affects considerably the entanglement dynamics, and usually leads to the loss of entanglement within a finite time. Since entanglement is a key feature in the application of such systems to quantum ... More
Fourier's Law: insight from a simple derivationDec 27 2008Feb 04 2009The onset of Fourier's law in a one-dimensional quantum system is addressed via a simple model of weakly coupled quantum systems in contact with thermal baths at their edges. Using analytical arguments we show that the crossover from the ballistic (invalid ... More
On PAC Extensions and Scaled Trace FormsMay 24 2007Aug 29 2007Any non-degenerate quadratic form over a Hilbertian field (e.g., a number field) is isomorphic to a scaled trace form. In this work we extend this result to more general fields. In particular, prosolvable and prime-to-p extensions of a Hilbertian field. ... More
Ramp Reversal Memory and Phase-Boundary Scarring in Transition Metal OxidesJul 02 2017Transition metal oxides (TMOs) are complex electronic systems which exhibit a multitude of collective phenomena. Two archetypal examples are VO2 and NdNiO3, which undergo a metal-insulator phase-transition (MIT), the origin of which is still under debate. ... More
Topological quantization of energy transport in micro- and nano-mechanical latticesJul 20 2017Mar 21 2018Topological effects typically discussed in the context of quantum physics are emerging as one of the central paradigms of physics. Here, we demonstrate the role of topology in energy transport through dimerized micro- and nano-mechanical lattices in the ... More
Crossover behavior of the thermal conductance and Kramers' transition rate theoryDec 19 2013Dec 08 2015Kramers' theory frames chemical reaction rates in solution as reactants overcoming a barrier in the presence of friction and noise. For weak coupling to the solution, the reaction rate is limited by the rate at which the solution can restore equilibrium ... More
Mechanical Tuning of Conductance and Thermopower in Helicene Molecular JunctionsApr 08 2015Helicenes are inherently chiral polyaromatic molecules composed of all-ortho fused benzene rings possessing a spring-like structure. Here, using a combination of density functional theory and tight-binding calculations, it is demonstrated that controlling ... More
Tunneling into clean Heavy Fermion Compounds: Origin of the Fano LineshapeAug 29 2010Recently observed tunneling spectra on clean heavy fermion compounds show a lattice periodic Fano lineshape similar to what is observed in the case of tunneling to a Kondo ion adsorbed at the surface. We show that the translation symmetry of a clean surface ... More
Local Current Distribution and "Hot Spots" in the Integer Quantum Hall RegimeJul 12 2006Jul 20 2006In a recent experiment, the local current distribution of a two-dimensional electron gas in the quantum Hall regime was probed by measuring the variation of the conductance due to local gating. The main experimental finding was the existence of "hot spots", ... More
RecA-mediated homology search as a nearly optimal signal detection systemNov 19 2010Homologous recombination facilitates the exchange of genetic material between homologous DNA molecules. This crucial process requires detecting a specific homologous DNA sequence within a huge variety of heterologous sequences. The detection is mediated ... More
Electron - Dark Matter Scattering in an Evacuated TubeJun 16 2008The light dark matter model can explain both the primordial abundance of dark matter and the anomalous 511 keV gamma-ray signal from the galactic center. This model posits a light neutral scalar, \chi, with a mass in the range 1 MeV < Mchi < 10 MeV, as ... More
The universal minimal space for groups of homeomorphisms of h-homogeneous spacesJun 01 2011Oct 13 2011Let X be a h-homogeneous zero-dimensional compact Hausdorff space, i.e. X is a Stone dual of a homogeneous Boolean algebra. It is shown that the universal minimal space M(G) of the topological group G=Homeo(X), is the space of maximal chains on X introduced ... More
Singular curves and the etale Brauer-Manin obstruction for surfacesDec 25 2012Nov 22 2013We construct a smooth and projective surface over an arbitrary number field that is a counterexample to the Hasse principle but has the infinite etale Brauer-Manin set. We also construct a surface with a unique rational point and the infinite etale Brauer-Manin ... More
Searching for an invisible A' vector boson with DarkLightSep 04 2012Jan 07 2013High-luminosity experiments are able to search for new physics at low energies, which could have evaded detection thus far due to very weak couplings to the Standard Model. The DarkLight experiment at Jefferson Lab is designed to search for a new U(1) ... More
A Juzvinskiĭ Addition Theorem for Finitely Generated Free Groups ActionsOct 23 2011Aug 08 2012The classical Juzvinski\u{i} Addition Theorem states that the entropy of an automorphism of a compact group decomposes along invariant subgroups. Thomas generalized the theorem to a skew-product setting. Using L. Bowen's f-invariant we prove the addition ... More
Embedding minimal dynamical systems into Hilbert cubesNov 05 2015We study the problem of embedding minimal dynamical systems into the shift action on the Hilbert cube $\left([0,1]^N\right)^{\mathbb{Z}}$. This problem is intimately related to the theory of mean dimension, which counts the averaged number of parameters ... More
Integer programs with a fixed radius L1-constraint are polynomial-time solvableSep 26 2016Integer programming problems with L1-constraints are ubiquitous. For instance, L1-constraints are found in multidimensional integer packing problems with a capacity constraint. This paper shows that nonlinear integer programs with an L1-constraint can ... More
Integer programs with a fixed radius L1-constraint are polynomial-time solvableSep 26 2016Oct 05 2016Integer programming problems with L1-constraints are ubiquitous. For instance, L1-constraints are found in multidimensional integer packing problems with a capacity constraint. This paper shows that nonlinear integer programs with an L1-constraint can ... More
Molecular Recognition as an Information Channel: The Role of Conformational ChangesJul 26 2010Molecular recognition, which is essential in processing information in biological systems, takes place in a crowded noisy biochemical environment and requires the recognition of a specific target within a background of various similar competing molecules. ... More
Are stable instances easy?Jun 17 2009We introduce the notion of a stable instance for a discrete optimization problem, and argue that in many practical situations only sufficiently stable instances are of interest. The question then arises whether stable instances of NP--hard problems are ... More
An integral model structure and truncation theory for coherent group actionsJun 12 2015In this work we study the homotopy theory of coherent group actions from a global point of view, where we allow both the group and the space acted upon to vary. Using the model of Segal group actions and the model categorical Grothendieck construction ... More
Bandits meet Computer Architecture: Designing a Smartly-allocated CacheJan 31 2016In many embedded systems, such as imaging sys- tems, the system has a single designated purpose, and same threads are executed repeatedly. Profiling thread behavior, allows the system to allocate each thread its resources in a way that improves overall ... More
Large-Scale Machine Translation between Arabic and Hebrew: Available Corpora and Initial ResultsSep 25 2016Machine translation between Arabic and Hebrew has so far been limited by a lack of parallel corpora, despite the political and cultural importance of this language pair. Previous work relied on manually-crafted grammars or pivoting via English, both of ... More
Zero-Delay and Causal Secure Source CodingNov 19 2013We investigate the combination between causal/zero-delay source coding and information-theoretic secrecy. Two source coding models with secrecy constraints are considered. We start by considering zero-delay perfectly secret lossless transmission of a ... More
Structure Theorems for Real-Time Variable-Rate Coding With and Without Side InformationAug 14 2011The output of a discrete Markov source is to be encoded instantaneously by a variable-rate encoder and decoded by a finite-state decoder. Our performance measure is a linear combination of the distortion and the instantaneous rate. Structure theorems, ... More
An explicit compact universal space for real flowsDec 24 2016Jul 27 2018The Kakutani-Bebutov Theorem (1968) states that any compact metric real flow whose fixed point set is homeomorphic to a subset of $\mathbb{R}$ embeds into the Bebutov flow, the $\mathbb{R}$-shift on $C(\mathbb{R},[0,1])$. An interesting fact is that this ... More
On processes which cannot be distinguished by finitary observationAug 13 2006A function $J$ defined on a family $C$ of stationary processes is finitely observable if there is a sequence of functions $s_n$ such that $s_n(x_1 ... x_n)\to J(X)$ in probability for every process $X=(x_n)\in C$. Recently, Ornstein and Weiss roved the ... More
On the Collapse of Charged Scalar FieldsJun 17 2003We explore numerically the evolution of a collapsing spherical shell of charged, massless scalar field. We obtain an external \RN space-time, and an inner space-time that is bounded by a singularity on the Cauchy Horizon. We compare these results with ... More
Adversarial Regularization for Visual Question Answering: Strengths, Shortcomings, and Side EffectsJun 20 2019Visual question answering (VQA) models have been shown to over-rely on linguistic biases in VQA datasets, answering questions "blindly" without considering visual context. Adversarial regularization (AdvReg) aims to address this issue via an adversary ... More
The Massey vanishing conjecture for number fieldsApr 13 2019A conjecture of Min\'a\v{c} and T\^an predicts that for any n>2, any prime p and any field k, the Massey product of n Galois cohomology classes in H^1(k,Z/pZ) must vanish if it is defined. We establish this conjecture when k is a number field.
Reconstruction Codes for DNA Sequences with Uniform Tandem-Duplication ErrorsJan 18 2018Oct 05 2018DNA as a data storage medium has several advantages, including far greater data density compared to electronic media. We propose that schemes for data storage in the DNA of living organisms may benefit from studying the reconstruction problem, which is ... More
Metric mean dimension and analog compressionDec 02 2018Jun 30 2019Wu and Verd\'u developed a theory of almost lossless analog compression, where one imposes various regularity conditions on the compressor and the decompressor with the input signal being modelled by a (typically infinite-entropy) stationary stochastic ... More
Zero-Delay and Causal Single-User and Multi-User Lossy Source Coding with Decoder Side InformationJan 01 2013We consider zero-delay single-user and multi-user source coding with average distortion constraint and decoder side information. The zero-delay constraint translates into causal (sequential) encoder and decoder pairs as well as the use of instantaneous ... More
Error Exponents for Broadcast Channels with Degraded Message SetsJun 07 2009We consider a broadcast channel with a degraded message set, in which a single transmitter sends a common message to two receivers and a private message to one of the receivers only. The main goal of this work is to find new lower bounds to the error ... More
On the fibration method for zero-cycles and rational pointsSep 03 2014Jun 22 2015Conjectures on the existence of zero-cycles on arbitrary smooth projective varieties over number fields were proposed by Colliot-Th\'el\`ene, Sansuc, Kato and Saito in the 1980's. We prove that these conjectures are compatible with fibrations, for fibrations ... More
Constructing expander graphs by 2-lifts and discrepancy vs. spectral gapDec 01 2003Apr 08 2004We present a new explicit construction for expander graphs with nearly optimal spectral gap. The construction is based on a series of 2-lift operations. Let $G$ be a graph on $n$ vertices. A 2-lift of $G$ is a graph $H$ on $2n$ vertices, with a covering ... More
Mean dimension and an embedding theorem for real flowsJun 05 2018Jul 04 2018We develop mean dimension theory for $\mathbb{R}$-flows. We obtain fundamental properties and examples and prove an embedding theorem: Any real flow $(X,\mathbb{R})$ of mean dimension strictly less than $r$ admits an extension $(Y,\mathbb{R})$ whose mean ... More
A Non-linear Differential CNN-Rendering Module for 3D Data EnhancementApr 09 2019In this work we introduce a differential rendering module which allows neural networks to efficiently process cluttered data. The module is composed of continuous piecewise differentiable functions defined as a sensor array of cells embedded in 3D space. ... More
On Choptuik's scaling in higher dimensionsFeb 03 2005Jun 06 2005We extend Choptuik's scaling phenomenon found in general relativistic critical gravitational collapse of a massless scalar field to higher dimensions. We find that in the range 4 <= D <= 11 the behavior is qualitatively similar to that discovered by Choptuik. ... More
Polarization and light curve variability: the "patchy shell" modelOct 08 2003Feb 05 2004Recent advances in early detection and detailed monitoring of GRB afterglows have revealed variability in some afterglow light curves. One of the leading models for this behavior is the patchy shell model. This model attributes the variability to random ... More
Monotone Maps, Sphericity and Bounded Second EigenvalueJan 22 2004We consider {\em monotone} embeddings of a finite metric space into low dimensional normed space. That is, embeddings that respect the order among the distances in the original space. Our main interest is in embeddings into Euclidean spaces. We observe ... More
On Real-Time and Causal Secure Source CodingMay 15 2012We investigate two source coding problems with secrecy constraints. In the first problem we consider real--time fully secure transmission of a memoryless source. We show that although classical variable--rate coding is not an option since the lengths ... More
Unsupervised Learning of Noisy-Or Bayesian NetworksSep 26 2013This paper considers the problem of learning the parameters in Bayesian networks of discrete variables with known structure and hidden variables. Previous approaches in these settings typically use expectation maximization; when the network has high treewidth, ... More
The Grothendieck construction for model categoriesApr 07 2014Jun 12 2015The Grothendieck construction is a classical correspondence between diagrams of categories and coCartesian fibrations over the indexing category. In this paper we consider the analogous correspondence in the setting of model categories. As a main result, ... More
Inducing Grammars with and for Neural Machine TranslationMay 28 2018Machine translation systems require semantic knowledge and grammatical understanding. Neural machine translation (NMT) systems often assume this information is captured by an attention mechanism and a decoder that ensures fluency. Recent work has shown ... More
Metric mean dimension and analog compressionDec 02 2018Wu and Verd\'u developed a theory of almost lossless analog compression, where one imposes various regularity conditions on the compressor and the decompressor with the input signal being modelled by a (typically infinite-entropy) stationary stochastic ... More
Analyzing the Structure of Attention in a Transformer Language ModelJun 07 2019Jun 18 2019The Transformer is a fully attention-based alternative to recurrent networks that has achieved state-of-the-art results across a range of NLP tasks. In this paper, we analyze the structure of attention in a Transformer language model, the GPT-2 small ... More