Results for "Yonatan Sivan"

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Instability of bound states of a nonlinear Schrödinger equation with a Dirac potentialJul 17 2007Dec 19 2007We study analytically and numerically the stability of the standing waves for a nonlinear Schr\"odinger equation with a point defect and a power type nonlinearity. A main difficulty is to compute the number of negative eigenvalues of the linearized operator ... 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
Nonlinear plasmonics at high temperaturesJul 12 2016We solve the Maxwell and heat equations self-consistently for metal nanoparticles under intense continuous wave (CW) illumination. Unlike previous studies, we rely on {\em experimentally}-measured data for the metal permittivity for increasing temperature ... More
Time-reversal in dynamically-tuned zero-gap periodic systemsApr 24 2011We show that short pulses propagating in zero-gap periodic systems can be reversed with 100% efficiency by using weak non-adiabatic tuning of the wave velocity at time-scales that can be much slower than the period. Unlike previous schemes, we demonstrate ... More
Robust Location of Optical Fiber Modes via the Argument Principle MethodSep 07 2016We implement a robust, globally convergent root search method for transcendental equations guaranteed to locate all complex roots within a specified search domain, based on Cauchy's residue theorem. Although several implementations of the argument principle ... More
Theory of wave-front reversal of short pulses in dynamically-tuned zero-gap periodic systemsMay 27 2011Recently, we have shown that the wave-front of short pulses can be accurately and efficiently reversed by use of simple one-dimensional zero-gap photonic crystals. In this Article, we describe the analytical approach in detail, and discuss specific structures ... More
Broadband time-reversal of optical pulses using a switchable photonic-crystal mirrorMay 27 2011Recently, Chumak et al. have demonstrated experimentally the time-reversal of microwave spin pulses based on non-adiabatically tuning the wave speed in a spatially-periodic manner. Here, we solve the associated wave equations analytically, and give an ... 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
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
Reinterpreting the magnetoelectric coupling of polarizability tensors of infinite cylinders using symmetry: a simple TM/TE viewJul 06 2016Recently, Strickland et al retrieved dynamic polarizabilities of infinitely long wires at oblique incidence, reporting non-zero magnetoelectric coupling, seemingly defying existing theorems which forbid this in centrosymmetric scatterers. We reconcile ... 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
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
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
Submodular Learning and Covering with Response-Dependent CostsFeb 23 2016Aug 29 2016We consider interactive learning and covering problems, in a setting where actions may incur different costs, depending on the response to the action. We propose a natural greedy algorithm for response-dependent costs. We bound the approximation factor ... 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
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
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
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
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
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
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
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
Loss minimization and parameter estimation with heavy tailsJul 07 2013Apr 18 2016This work studies applications and generalizations of a simple estimation technique that provides exponential concentration under heavy-tailed distributions, assuming only bounded low-order moments. We show that the technique can be used for approximate ... More
Effective Stiffness: Generalizing Effective Resistance Sampling to Finite Element MatricesOct 20 2011Jan 27 2014We define the notion of effective stiffness and show that it can used to build sparsifiers, algorithms that sparsify linear systems arising from finite-element discretizations of PDEs. In particular, we show that sampling $O(n\log n)$ elements according ... More
Nonsteady-state diffusion in two-dimensional periodic channelsFeb 12 2019The dynamics of a freely diffusing particle in a two-dimensional channel with cross sectional area $A(x)$, can be effectively described by a one-dimensional diffusion equation under the action of a potential of mean force $U(x)=-k_BT\ln [A(x)]$ (where ... More
Multi-Instance Learning with Any Hypothesis ClassJul 11 2011Aug 13 2012In the supervised learning setting termed Multiple-Instance Learning (MIL), the examples are bags of instances, and the bag label is a function of the labels of its instances. Typically, this function is the Boolean OR. The learner observes a sample of ... More
Vickrey Auctions for Irregular DistributionsJun 17 2013Oct 04 2013The classic result of Bulow and Klemperer \cite{BK96} says that in a single-item auction recruiting one more bidder and running the Vickrey auction achieves a higher revenue than the optimal auction's revenue on the original set of bidders, when values ... 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
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
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
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
Frequency-domain simulations of a negative-index material with embedded gainDec 01 2009Dec 02 2009We solve the equations governing light propagation in a negative-index material with embedded nonlinearly saturable gain material using a frequency-domain model. We show that available gain materials can lead to complete loss compensation only if they ... More
Nanoparticle-assisted STED nanoscopy with gold nanospheresOct 31 2016We demonstrate stimulated emission depletion (STED) microscopy with 20 nm gold nanospheres coated by fluorescent silica. Compared with previous demonstrations of STED with a hybrid plasmonic fluorescent label, the current implementation offers a substantially ... More
Conformational Proofreading: The Impact of Conformational Changes on the Specificity of Molecular RecognitionJul 26 2010To perform recognition, molecules must locate and specifically bind their targets within a noisy biochemical environment with many look-alikes. Molecular recognition processes, especially the induced-fit mechanism, are known to involve conformational ... 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
Limited-Magnitude Error-Correcting Gray Codes for Rank ModulationJan 20 2016Jun 19 2016We construct Gray codes over permutations for the rank-modulation scheme, which are also capable of correcting errors under the infinity-metric. These errors model limited-magnitude or spike errors, for which only single-error-detecting Gray codes are ... More
Snake-in-the-Box Codes for Rank ModulationJul 18 2011Motivated by the rank-modulation scheme with applications to flash memory, we consider Gray codes capable of detecting a single error, also known as snake-in-the-box codes. We study two error metrics: Kendall's $\tau$-metric, which applies to charge-constrained ... More
Mean dimension and a sharp embedding theorem: extensions of aperiodic subshiftsJul 17 2012We show that if $(X,T)$ is an extension of an aperiodic subshift (a subsystem of $({1,2,...,l}^{\mathbb{Z}},\mathrm{shift})$ for some $l\in\mathbb{N}$) and has mean dimension $mdim(X,T)<\frac{D}{2}$ $(D\in \mathbb{N}$), then it embeds equivariantly in ... More
Minimal hyperspace actions of homeomorphism groups of h-homogeneous spacesJul 07 2011May 07 2012Let X be a h-homogeneous zero-dimensional compact Hausdorff space, i.e. X is a Stone dual of a homogeneous Boolean algebra. Using the dual Ramsey theorem and a detailed combinatorial analysis of what we call stable collections of subsets of a finite set, ... More
Locality in Theory SpaceFeb 24 2012Jun 27 2012Locality is a guiding principle for constructing realistic quantum field theories. Compactified theories offer an interesting context in which to think about locality, since interactions can be nonlocal in the compact directions while still being local ... More
A Character-level Convolutional Neural Network for Distinguishing Similar Languages and DialectsSep 24 2016Discriminating between closely-related language varieties is considered a challenging and important task. This paper describes our submission to the DSL 2016 shared-task, which included two sub-tasks: one on discriminating similar languages and one on ... More
Comment on "Critical behavior of the Pauli spin susceptibility..." by A. A. Shashkin et. alOct 17 2004The paper by A. A. Shashkin et al. [cond-mat/0409100] reports measurements of the thermodynamic magnetization of two-dimensional electrons in silicon. Although the experimental data is very similar to that reported by us more then two years ago, the authors ... More
Interactive algorithms: from pool to streamFeb 02 2016Jun 16 2016We consider interactive algorithms in the pool-based setting, and in the stream-based setting. Interactive algorithms observe suggested elements (representing actions or queries), and interactively select some of them and receive responses. Pool-based ... More
Active Regression by StratificationOct 22 2014We propose a new active learning algorithm for parametric linear regression with random design. We provide finite sample convergence guarantees for general distributions in the misspecified model. This is the first active learner for this setting that ... More
Hot-Jupiter Inflation due to Deep Energy DepositionJan 09 2015Apr 24 2015Some extrasolar giant planets in close orbits---"hot Jupiters"---exhibit larger radii than that of a passively cooling planet. The extreme irradiation $L_{\rm eq}$ these hot Jupiters receive from their close in stars creates a thick isothermal layer in ... More
Bitcoin's Security Model RevisitedMay 30 2016May 31 2016We revisit the fundamental question of Bitcoin's security against double spending attacks. While previous work has bounded the probability that a transaction is reversed, we show that no such guarantee can be effectively given if the attacker can choose ... 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
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
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
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
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
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
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
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
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
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
Optimal Design of a Molecular Recognizer: Molecular Recognition as a Bayesian Signal Detection ProblemJul 26 2010Numerous biological functions-such as enzymatic catalysis, the immune response system, and the DNA-protein regulatory network-rely on the ability of molecules to specifically recognize target molecules within a large pool of similar competitors in a noisy ... 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
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
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
The Étale Homotopy Type and Obstructions to the Local-Global PrincipleFeb 07 2010Nov 30 2011In 1969 Artin and Mazur defined the \'etale homotopy type of an algebraic variety \cite{AMa69}. In this paper we define various obstructions to the local-global principle on a variety $X$ over a global field using the \'etale homotopy type of $X$ and ... More
Homotopy Obstructions to Rational PointsOct 02 2011In this paper we propose to use a relative variant of the notion of the \'{e}tale homotopy type of an algebraic variety in order to study the existence of rational points on it. In particular, we use an appropriate notion of homotopy fixed points in order ... 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
Single-Call MechanismsNov 29 2010Mar 29 2012Truthfulness is fragile and demanding. It is oftentimes computationally harder than solving the original problem. Even worse, truthfulness can be utterly destroyed by small uncertainties in a mechanism's outcome. One obstacle is that truthful payments ... More
Temperature-dependent permittivity of annealed and unannealed gold filmsMar 25 2016Sep 19 2016Due to local field enhancement and subwavelength confinements, nano-plasmonics provide numerous novel applications. Simultaneously, as an efficient nanoscale heat generator from inherent absorption, thermo-plasmonics is emerging as an important branch. ... 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
Discrete Self-Similarity in Type-II Strong ExplosionsJul 10 2009We present new solutions to the strong explosion problem in a non-power law density profile. The unperturbed self-similar solutions discovered by Waxman & Shvarts describe strong Newtonian shocks propagating into a cold gas with a density profile falling ... More
Minimizing the Maximal Loss: How and Why?Feb 04 2016May 22 2016A commonly used learning rule is to approximately minimize the \emph{average} loss over the training set. Other learning algorithms, such as AdaBoost and hard-SVM, aim at minimizing the \emph{maximal} loss over the training set. The average loss is more ... More
Short range attraction between two similarly charged silica surfacesDec 26 2005Using an Atomic Force Microscope (AFM) we measure the interaction between two identically charged silica surfaces in the presence of saline solution. For pure NaCl the interaction is always repulsive. Upon addition of cobalt hexamine ions, [Co(NH3)6]+3, ... More
Tight Sample Complexity of Large-Margin LearningNov 23 2010Apr 05 2012We obtain a tight distribution-specific characterization of the sample complexity of large-margin classification with L_2 regularization: We introduce the \gamma-adapted-dimension, which is a simple function of the spectrum of a distribution's covariance ... More
Auditing: Active Learning with Outcome-Dependent Query CostsJun 10 2013Jul 12 2015We propose a learning setting in which unlabeled data is free, and the cost of a label depends on its value, which is not known in advance. We study binary classification in an extreme case, where the algorithm only pays for negative labels. Our motivation ... More
Efficient Active Learning of Halfspaces: an Aggressive ApproachAug 17 2012May 25 2013We study pool-based active learning of half-spaces. We revisit the aggressive approach for active learning in the realizable case, and show that it can be made efficient and practical, while also having theoretical guarantees under reasonable assumptions. ... More
Lower Bounds on Revenue of Approximately Optimal AuctionsOct 01 2012We obtain revenue guarantees for the simple pricing mechanism of a single posted price, in terms of a natural parameter of the distribution of buyers' valuations. Our revenue guarantee applies to the single item n buyers setting, with values drawn from ... More
Optimal Crowdsourcing ContestsNov 12 2011We study the design and approximation of optimal crowdsourcing contests. Crowdsourcing contests can be modeled as all-pay auctions because entrants must exert effort up-front to enter. Unlike all-pay auctions where a usual design objective would be to ... More
Wilkinson's Inertia-Revealing Factorization and Its Application to Sparse MatricesNov 27 2015We propose a new inertia-revealing factorization for sparse matrices. The factorization scheme and the method for extracting the inertia from it were proposed in the 1960s for dense, banded, or tridiagonal matrices, but they have been abandoned in favor ... More
Blackbody Radiation from Isolated NeptunesMar 09 2016Recent analyses of the orbits of some Kuiper Belt objects hypothesize the presence of an undiscovered Neptune-size planet at a very large separation from the Sun. The energy budget of Neptunes on such distant orbits is dominated by the internal heat released ... More
Tight Lower Bounds for Multiplicative Weights Algorithmic FamiliesJul 11 2016Jul 14 2016We study the fundamental problem of prediction with expert advice and develop regret lower bounds for a large family of algorithms for this problem. We develop simple adversarial primitives, that lend themselves to various combinations leading to sharp ... More
Perfect Bayesian Equilibria in Repeated SalesSep 10 2014Oct 27 2014A special case of Myerson's classic result describes the revenue-optimal equilibrium when a seller offers a single item to a buyer. We study a repeated sales extension of this model: a seller offers to sell a single fresh copy of an item to the same buyer ... More