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Quantifying brain microstructure with diffusion MRI: Theory and parameter estimationDec 06 2016We review, systematize and discuss models of diffusion in neuronal tissue, by putting them into an overarching physical context of coarse-graining over an increasing diffusion length scale. From this perspective, we view research on quantifying brain ... More

A Deep Unsupervised Learning Approach Toward MTBI Identification Using Diffusion MRIFeb 08 2018Mild traumatic brain injury (mTBI) is a growing public health problem with an estimated incidence of one million people annually in US. Neurocognitive tests have been used to both assess the patient condition and to monitor the patient progress. This ... More

Universal power-law scaling of water diffusion in human brain defines what we see with MRISep 28 2016Development of successful therapies for neurological disorders depends on our ability to diagnose and monitor the progression of underlying pathologies at the cellular level. Physics and physiology limit the resolution of human MRI to millimeters, three ... More

Mapping orientational and microstructural metrics of neuronal integrity with in vivo diffusion MRISep 28 2016Diagnosis of brain disorders is hindered by the lack of an imaging technique that reveals the architecture of neuronal tissue at the cellular level, where the associated pathological processes develop. Accessing tissue integrity at the micrometer scale, ... More

Diffusion distinguishes between structural universality classes of disordered mediaJul 28 2016Identifying relevant parameters is central to understanding complex phenomena. This often evokes the concept of universality, which groups microscopically distinct systems into a handful of universality classes, according to the relevant degrees of freedom ... More

Characterizing microstructure of living tissues with time-dependent diffusionOct 10 2012Molecular diffusion measurements are widely used to probe microstructure in materials and living organisms noninvasively. The precise relation of diffusion metrics to microstructure remains a major challenge: In complex samples, it is often unclear which ... More

Random walk with barriers: Diffusion restricted by permeable membranesApr 15 2010Sep 20 2010Restrictions to molecular motion by barriers (membranes) are ubiquitous in biological tissues, porous media and composite materials. A major challenge is to characterize the microstructure of a material or an organism nondestructively using a bulk transport ... More

Generalized Riesz Products on the Bohr compactification of $\R$Jun 03 2012Dec 19 2014We study a class of generalized Riesz products connected to the spectral type of some class of rank one flows on $\R$. Applying a Central Limit Theorem of Kac, we exhibit a large class of singular generalized Riesz products on the Bohr compactification ... More

The Rudin-Shapiro polynomials and The Fekete polynomials are not $L^α$-flatMar 13 2016Apr 15 2016We establish that the Rudin-Shapiro polynomials are not $L^\alpha$-flat, for any $\alpha \geq 0$. We further prove that the "truncated" Rudin-Shapiro sequence cannot generate a sequence of $L^\alpha$-flat polynomials, for any $\alpha \geq 0$. In the appendix, ... More

A new class of rank one transformations with singular spectrumApr 18 2007We introduce a new tool to study the spectral type of rank one transformations using the method of central limit theorem for trigonometric sums. We get some new applications.

On the spectrum of $α$-rigid mapsFeb 16 2009Apr 02 2009It is shown that there exists an $\alpha$-rigid transformation with $\alpha$ less or equal to $\frac12$ whose spectrum has Lebesgue component. This answers the question raised by Klemes and Reinhold in \cite{Klemes-Reinhold}. We exhibit also a large class ... More

On the spectral type of some class of rank one flowsMay 24 2012Aug 10 2012It is shown that a certain class of Riesz product type measure on $\R$ is singular. This proves the singularity of the spectral types of some class of rank one flows. Our method is based on the extension of the Central Limit Theorem approach to the real ... More

A simple proof of Bourgain's theorem on the singularity of the spectrum of Ornstein's mapsAug 26 2015Aug 30 2015We give a simple proof of Bourgain's theorem on the singularity of Ornstein's maps.

Ergodic Banach problem, flat polynomials and Mahler's measures with combinatoricsAug 26 2015Jan 06 2016We construct a sequence of polynomials that are flat in the almost everywhere sense. The construction is done by appealing to the nice combinatorial properties of the Singer's sets and Sidon sets. As a consequence, we get a positive answer to Littlewood's ... More

On the Erdös flat polynomials problemSep 12 2016There are no square $L^2$-flat sequences of polynomials of the type $$\frac{1}{\sqrt q}(\epsilon_0 + \epsilon_1z + \epsilon_2z^2 + \cdots + \epsilon_{q-2}z^{q-2} +\epsilon_q z^{q-1}),$$ where for each $j,~~ 0 \leq j\leq q-1,~\epsilon_j = \pm 1$. It follows ... More

The PAH hypothesis after 25 yearsNov 15 2011The infrared spectra of many galactic and extragalactic objects are dominated by emission features at 3.3, 6.2, 7.7, 8.6 and 11.2 \mu m. The carriers of these features remained a mystery for almost a decade, hence the bands were dubbed the unidentified ... More

Multi-Topic Multi-Document SummarizerJan 03 2014Current multi-document summarization systems can successfully extract summary sentences, however with many limitations including: low coverage, inaccurate extraction to important sentences, redundancy and poor coherence among the selected sentences. The ... More

An Accurate Arabic Root-Based Lemmatizer for Information Retrieval PurposesMar 15 2012In spite of its robust syntax, semantic cohesion, and less ambiguity, lemma level analysis and generation does not yet focused in Arabic NLP literatures. In the current research, we propose the first non-statistical accurate Arabic lemmatizer algorithm ... More

Resonant final-state interactions in D^0 -> \bar{K}^{0} η, \bar{K}^{0} η' DecayOct 13 1999We have investimated the effect of the isospin 1/2, J^P = 0^+ resonant state K^*_0(1950) on the decays D^0 ->\bar{K}^{0}\eta and D^0 ->\bar{K}^0 \eta' as a function of the branching ratio sum r =Br(K^*_0(1950)->\bar{K}^0\eta)+ Br(K^*_0(1950)->\bar{K}^0 ... More

Helicity and partial wave amplitude analysis of D -> K^* ρdecayOct 14 1999We have carried out an analysis of helicity and partial-wave amplitudes for the process D -> K^* \rho in the factorization approximation using several models for the form factors. All the models, with the exception of one, generate partial-wave amplitudes ... More

A cubic nonconventional ergodic average with Möbius and Liouville weightApr 03 2015May 16 2015It is shown that the cubic nonconventional ergodic average of order 2 with M\"obius and Liouville weight converge almost surely to zero. As a consequence, we obtain that the Ces\`aro mean of the self-correlations and some moving average of the self-correlations ... More

The Best Templates Match Technique For Example Based Machine TranslationJun 04 2014It has been proved that large scale realistic Knowledge Based Machine Translation applications require acquisition of huge knowledge about language and about the world. This knowledge is encoded in computational grammars, lexicons and domain models. Another ... More

A Lemma Based Evaluator for Semitic Language Text Summarization SystemsMar 22 2014Matching texts in highly inflected languages such as Arabic by simple stemming strategy is unlikely to perform well. In this paper, we present a strategy for automatic text matching technique for for inflectional languages, using Arabic as the test case. ... More

Keyphrase Based Arabic Summarizer (KPAS)Jun 23 2012This paper describes a computationally inexpensive and efficient generic summarization algorithm for Arabic texts. The algorithm belongs to extractive summarization family, which reduces the problem into representative sentences identification and extraction ... More

NC Effective Gauge Model for Multilayer FQH StatesAug 20 2002We develop an effective field model for describing FQH states with rational filling factors that are not of Laughlin type. These kinds of systems, which concern single layer hierarchical states and multilayer ones, were observed experimentally; but have ... More

Spin-Magnetic Field Interaction and Realization of Fractional SupersymmetryAug 06 2001The fractional supersymmetry in the case of the non-relativistic motion of one anyon with fractional spin is realized. Thus the associated Hamiltonian is discussed.

Approximate transitivity property and Lebesgue spectrumMar 03 2009Mar 08 2009Exploiting a spectral criterion for a system not to be AT we give some new examples of zero entropy systems without the AT property. Our examples include those with finite spectral multiplicity -- in particular we show that the system arising from the ... More

D-branes on Noncommutative OrbifoldsMay 19 2001We study tachyon condensation on noncommutative toric orbifolds with a $Z_2$ discrete group and explore the various kins of brane bound states arising in the case of irrational values of the B-field. We show that $Z_$ symmetry of the orbifolds incorporates ... More

Solitons on compact and noncompact spaces in large noncommutativityDec 28 2000Jan 06 2001We study solutions at the minima of scalar field potentials for Moyal spaces and torii in the large non-commutativity and interprete these solitons in terms of non-BPS D-branes of string theory. We derive a mass spectrum formula linking different D-branes ... More

A cubic nonconventional ergodic average with multiplicative or Mangoldt weightsJun 17 2016Nov 04 2016We show that the cubic nonconventional ergodic averages of any order with a bounded multiplicative function weight converge almost surely to zero provided that the multiplicative function satisfies a strong Daboussi-Delange condition. We further obtain ... More

Propagation of initial errors on the parameters for linear and Gaussian state space modelsMar 14 2013For linear and Gaussian state space models parametrized by $\theta_0 \in \Theta \subset \R^{r}, r \geq 1$ corresponding to the vector of parameters of the model, the Kalman filter gives exactly the solution for the optimal filtering under weak assumptions. ... More

Are Stock Markets Integrated? Evidence from a Partially Segmented ICAPM with Asymmetric EffectsMay 24 2009In this paper, we test a partially segmented ICAPM for two developed markets, two emerging markets and World market, using an asymmetric extension of the multivariate GARCH process of De Santis and Gerard (1997,1998). We find that this asymmetric process ... More

Resolution of a shock in hyperbolic systems modified by weak dispersionMar 07 2005Feb 06 2006We present a way to deal with dispersion-dominated ``shock-type'' transition in the absence of completely integrable structure for the systems that one may characterize as strictly hyperbolic regularized by a small amount of dispersion. The analysis is ... More

The thermodynamic limit of the Whitham equationsOct 13 2003The infinite-genus limit of the KdV-Whitham equations is derived. The limit involves special scaling for the associated spectral surface such that the integrated density of states remains finite as $N \to \infty$ (the thermodynamic type limit). The limiting ... More

Multipliers of uniform topological algebrasAug 19 2016Let $E$ be a complete uniform topological algebra with Arens-Michael normed factors $\left(E_{\alpha}\right)_{\alpha\in\Lambda}.$ Then $M\left(E\right) \cong \varprojlim M\left(E_{\alpha}\right)$ within an algebra isomorphism $\varphi$. If each factor ... More

A real p-homogeneous seminorm with square property is submultiplicativeJan 09 2013Nov 27 2013We give a functional representation theorem for a class of real p-Banach algebras. This theorem is used to show that every p-homogeneous seminorm with square property on a real associative algebra is submultiplicative.

A remark on continuity of positive linear functionals on separable Banach *-algebrasJan 07 2013Apr 29 2014Using a variation of the Murphy-Varopoulos Theorem, we give a new proof of the following R.J.Loy Theorem: Let A be a separable Banach*-algebra with center Z such that ZA has at most countable codimension, then every positive linear functional on A is ... More

To Sense or Not To SenseJun 27 2012A longer sensing time improves the sensing performance; however, with a fixed frame size, the longer sensing time will reduce the allowable data transmission time of the secondary user (SU). In this paper, we try to address the tradeoff between sensing ... More

Controllability of fractional stochastic neutral functional differential equations driven by fractional Brownian motion with infinite delayApr 14 2016In this paper we study the controllability of fractional neutral stochastic functional differential equations with infinite delay driven by fractional Brownian motion in a real separable Hilbert space. The controllability results are obtained by using ... More

A rate of convergence result for the largest eigenvalue of complex white Wishart matricesSep 30 2004Feb 28 2007It has been recently shown that if $X$ is an $n\times N$ matrix whose entries are i.i.d. standard complex Gaussian and $l_1$ is the largest eigenvalue of $X^*X$, there exist sequences $m_{n,N}$ and $s_{n,N}$ such that $(l_1-m_{n,N})/s_{n,N}$ converges ... More

The Onsager AlgebraMay 27 2012In this thesis, four realizations of the Onsager algebra are explored. We begin with its original definition as introduced by Lars Onsager. We then examine how the Onsager algebra can be presented as a Lie algebra with two generators and two relations. ... More

Vers une interface pour l enrichissement des requetes en arabe dans un systeme de recherche d informationFeb 06 2014This presentation focuses on the automatic expansion of Arabic request using morphological analyzer and Arabic Wordnet. The expanded request is sent to Google.

1.5 billion words Arabic CorpusNov 12 2016This study is an attempt to build a contemporary linguistic corpus for Arabic language. The corpus produced, is a text corpus includes more than five million newspaper articles. It contains over a billion and a half words in total, out of which, there ... More

Hardy and Hardy-Sobolev inequalities on Riemannian manifoldsApr 04 2015Nov 13 2015Let $ (M,g) $ be a smooth compact Riemannian manifold of dimension $ N \geq 3 $. Given $p_0 \in M$, $\lambda \in \mathcal{R}$ and $\sigma \in (0,2]$, we study existence and non existence of minimizers of the following quotient: \begin{equation}\label{Paper ... More

Second Eigenvalue of the Yamabe Operator and ApplicationsApr 05 2012Let $(M, g)$ be a compact Riemannian manifold of dimension $n \geq 3$. In this paper, we give various properties of the eigenvalues of the Yamabe operator $L_g$. In particular, we show how the second eigenvalue of $L_g$ is related to the existence of ... More

The Joint Signature and Encryption RevisitedOct 29 2016We study the Sign_then_Encrypt, Commit_then_Encrypt_and_Sign, and Encrypt_then_Sign paradigms in the context of two cryptographic primitives, namely designated confirmer signatures and signcryption. Our study identifies weaknesses in those paradigms which ... More

$D_s^+ \to φρ^+$ DecayJan 08 1998Motivated by the experimental measurement of the decay rate, $\Gamma$, and the longitudinal polarization, $P_L$, in the Cabibbo favored decay $D_s^+\to \phi {\rho}^{+}$, we have studied theoretical prediction within the context of factorization approximation ... More

Kinetic models of immediate exchangeMay 06 2015We propose a novel kinetic exchange model differing from previous ones in two main aspects. First, the basic dynamics is modified in order to represent economies where immediate wealth exchanges are carried out, instead of reshufflings or uni-directional ... More

Isoperimetric inequalities for the eigenvalues of natural Schrödinger operators on surfacesFeb 12 2009This paper deals with eigenvalue optimization problems for a family of natural Schr\"odinger operators arising in some geometrical or physical contexts. These operators, whose potentials are quadratic in curvature, are considered on closed surfaces immersed ... More

Ample tangent bundle on smooth projective stacksNov 06 2016We study ample vector bundles on smooth projective stacks. In particular, we prove that the tangent bundle for the weighted projective stack $\mathbb{P}(a_0,...,a_n)$ is ample. A result of Mori shows that the only smooth projective varieties with ample ... More

Plancherel Theorem on the Symplectic Group SP(4,R)Aug 17 2016Let H be the 15- dimensional connected semisimple Lie group with its Iwasawa decomposition of H. Let G be the group of the semi direct product of H and the four dimensional real vector group . The goal of this paper is to define the Fourier transform ... More

Abstract Harmonic Analysis on the General Linear Group GL(n,R)Apr 20 2014Consider the general linear group, which is not connected but rather has two connected components, the matrices with positive determinant and the ones with negative determinant. Consider the Iwasawa decomposition of its special linear group. We adopt ... More

Plancherel Theorem and the Left Ideals of the Group Algebra for the Jacobi GroupJan 11 2016Let G be the three dimensional connected real semisimple Lie group and let KAN be the Iwasawa decomposition of G.Let J be the Jacobi group, which is the semidirect product of the two groups Heisenberg group with G. The Jacobi group plays an important ... More

Measuring and hedging financial risks in dynamical worldMay 01 2003Financial markets have developed a lot of strategies to control risks induced by market fluctuations. Mathematics has emerged as the leading discipline to address fundamental questions in finance as asset pricing model and hedging strategies. History ... More

Stochastic Optimal Multi-Modes Switching with a Viscosity Solution ApproachFeb 07 2011We consider the problem of optimal multi-modes switching in finite horizon, when the state of the system, including the switching cost functions are arbitrary ($g_{ij}(t,x)\geq 0$). We show existence of the optimal strategy, and give when the optimal ... More

Deterministic Minimax Impulse Control in Finite Horizon: the Viscosity Solution ApproachMar 17 2010We study here the impulse control minimax problem. We allow the cost functionals and dynamics to be unbounded and hence the value functions can possibly be unbounded. We prove that the value function of the problem is continuous. Moreover, the value function ... More

On alternating sums of binomial coefficients and $q$-binomial coefficientsMar 12 2016Jun 04 2016In this paper we shall evaluate two alternating sums of binomial coefficients by a combinatorial argument. Moreover, by combining the same combinatorial idea with partition theoretic techniques, we provide $q$-analogues involving the $q$-binomial coefficients. ... More

Distributed Data and Programs SlicingFeb 24 2014This paper presents a new technique for data slicing of distributed programs running on a hierarchy of machines. Data slicing can be realized as a program transformation that partitions heaps of machines in a hierarchy into independent regions. Inside ... More

A stochastic volatility model with jumpsMar 22 2006Oct 28 2011We consider a stochastic volatility model with jumps where the underlying asset price is driven by the process sum of a 2-dimensional Brownian motion and a 2-dimensional compensated Poisson process. The market is incomplete, resulting in infinitely many ... More

Ghost cohomologies and new discrete states in supersymmetric c=1 modelMay 09 2014As of today, string theory appears to be one of the most promising physical models unifying the fundamental interactions in nature, such as electromagnetic (gauge) interactions and the gravity. While the perturbative theory of strings appears to be well ... More

Lee-Yang Model in Presence of DefectsFeb 13 2015Feb 16 2015I choose the Lee-Yang model and go through different approaches to analyze it using the form factor approach and the bootstrap program, the lattice description and the lattice TBA equations for a full understanding of the model. The bootstrap program ... More

Multi-agents Architecture for Semantic Retrieving Video in Distributed EnvironmentJul 30 2014Jul 31 2014This paper presents an integrated multi-agents architecture for indexing and retrieving video information.The focus of our work is to elaborate an extensible approach that gathers a priori almost of the mandatory tools which palliate to the major intertwining ... More

Combinatorial Identities Involving Mertens Function Through Relatively Prime SubsetsDec 08 2009In this note we give some identities which involve the Mertens function M(n). Our proofs are combinatorial with relatively prime subsets as a main tool.

Compatibility Condition between ring and coringJan 23 2007We introduce the notion of bi-monoid in general monoidal category generalizing by this the notion of bialgebra. In the case of bimodules over a noncommutative algebra, we obtain a compatibility condition between ring and coring whenever both structures ... More

Optimal Multi-Modes Switching Problem in Infinite HorizonApr 04 2009This paper studies the problem of the deterministic version of the Verification Theorem for the optimal m-states switching in infinite horizon under Markovian framework with arbitrary switching cost functions. The problem is formulated as an extended ... More

Concentration of measure and spectra of random matrices: Applications to correlation matrices, elliptical distributions and beyondDec 10 2009We place ourselves in the setting of high-dimensional statistical inference, where the number of variables $p$ in a data set of interest is of the same order of magnitude as the number of observations $n$. More formally, we study the asymptotic properties ... More

On the Construction of Generalized Grassmann Coherent StatesNov 07 2005A generalized definition of a deformation of the fermionic oscillator (k-fermionic oscillators) is proposed. Two prescriptions for the construction of generalized Grassmann coherent states for this kind of oscillators are derived. The two prescriptions ... More

Graded Brauer groups of a groupoid with involutionFeb 09 2012Feb 23 2014We define a group $RBr(\mathcal{G})$ containing, in a sense, the graded complex and orthogonal Brauer groups of a locally compact groupoid $\mathcal{G}$ equipped with an involution. When the involution is trivial, we show that the new group naturally ... More

Critical density of a soliton gasDec 08 2015Feb 15 2016We quantify the notion of a dense soliton gas by establishing an upper bound for the integrated density of states of the quantum-mechanical Schr\"odinger operator associated with the KdV soliton gas dynamics. As a by-product of our derivation we find ... More

On uniform topological algebrasJan 20 2013Oct 18 2013The uniform norm on a uniform normed Q-algebra is the only uniform Q-algebra norm on it. The uniform norm on a regular uniform normed Q-algebra with unit is the only uniform norm on it. Let A be a uniform topological algebra whose spectrum M (A) is equicontinuous, ... More

Optimal Spectrum Access for Cognitive RadiosAug 22 2012Mar 24 2013In this paper, we investigate a time-slotted cognitive setting with buffered primary and secondary users. In order to alleviate the negative effects of misdetection and false alarm probabilities, a novel design of spectrum access mechanism is proposed. ... More

On Conformal Paneitz Curvature Equations in Higher Dimensional SpheresDec 06 2004We study the problem of prescribing the Paneitz curvature on higher dimensional spheres. Particular attention is paid to the blow-up points, i.e. the critical points at infinity of the corresponding variational problem. Using topological tools and a careful ... More

Nonparametric regression estimation for random fields in a fixed-designFeb 04 2005We investigate the nonparametric estimation for regression in a fixed-design setting when the errors are given by a field of dependent random variables. Sufficient conditions for kernel estimators to converge uniformly are obtained. These estimators can ... More

Program Optimization Based Pointer Analysis and Live Stack-Heap AnalysisApr 04 2011In this paper, we present type systems for flow-sensitive pointer analysis, live stack-heap (variables) analysis, and program optimization. The type system for live stack-heap analysis is an enrichment of that for pointer analysis; the enrichment has ... More

The homogenized equation of a heterogenous Reaction-Diffusion model involving pulsating traveling frontsJul 28 2009Mar 29 2011The goal of this paper is to find the homogenized equation of a heterogenous Fisher-KPP model in a periodic medium. The solutions of this model are pulsating travelling fronts whose \emph{speeds} are superior to a parametric minimal speed $c^*_L$. We ... More

The spectrum of kernel random matricesJan 04 2010We place ourselves in the setting of high-dimensional statistical inference where the number of variables $p$ in a dataset of interest is of the same order of magnitude as the number of observations $n$. We consider the spectrum of certain kernel random ... More

Topological SL(2) Gauge Theory on ConifoldJan 04 2006Using a two component $SL(2) $ isospinor formalism, we study the link between conifold $T^{\ast}\mathbb{S}^{3}$ and q-deformed non commutative holomorphic geometry in complex four dimensions. Then, thinking about conifold as a projective complex three ... More

Hyperbolic Invariance in Type II SuperstringsFeb 20 2005We first review aspects of Kac Moody indefinite algebras with particular focus on their hyperbolic subset. Then we present two field theoretical systems where these structures appear as symmetries. The first deals with complete classification of $\mathcal{N}=2$ ... More

Mutation Symmetries in BPS Quiver Theories: Building the BPS SpectraApr 02 2012Aug 14 2012We study the basic features of BPS quiver mutations in 4D $\mathcal{N}=2$ supersymmetric quantum field theory with $G=ADE$ gauge symmetries.\ We show, for these gauge symmetries, that there is an isotropy group $\mathcal{G}_{Mut}^{G}$ associated to a ... More

Dead code elimination based pointer analysis for multithreaded programsDec 20 2012This paper presents a new approach for optimizing multitheaded programs with pointer constructs. The approach has applications in the area of certified code (proof-carrying code) where a justification or a proof for the correctness of each optimization ... More

Short proofs for $q$-Raabe formula and integrals for Jacobi theta functionsSep 22 2016We shall answer a question of Mez\H{o} on the $q$-analogue of the Raabe's integral formula for $0<q<1$ and we shall evaluate an integral involving the first theta function. Moreover, we will reproduce short proofs for some identities of Mez\H{o}.

A gamma function in two variablesMay 09 2013We introduce a gamma function $\Ga(x,z)$ in two complex variables which extends the classical gamma function $\Ga(z)$ in the sense that $\lim_{x\to 1}\Ga(x,z)=\Ga(z)$. We will show that many properties which $\Ga(z)$ enjoys extend in a natural way to ... More

Single Blow up Solutions for a Slightly Subcritical Biharmonic EquationDec 06 2004In this paper, we consider a biharmonic equation under the Navier boundary condition and with a nearly critical exponent $(P_\epsilon): \Delta^2u=u^{9-\epsilon}, u>0$ in $\Omega$ and $u=\Delta u=0$ on $\partial\Omega$, where $\Omega$ is a smooth bounded ... More

Extended Distributive Law: Co-wreath over co-ringsDec 28 2006A basic theory of cowreath or extended distributive laws in the bicategory of unital bimodules, is deciphered. Precisely, we give in terms of tensor product over a scalar base ring, a simplest and equivalent definition for cowreath over coring and for ... More

On geometrically transitive Hopf algebroidsAug 24 2015Oct 26 2015This paper contributes in the characterization of a certain class of commutative Hopf algebroids. It is shown that a given commutative flat Hopf algebroid with a non trivial base ring and a non empty characters groupoid, is geometrically transitive if ... More

On groupoids with involutions and their cohomologyFeb 01 2012Feb 06 2012We extend the definitions and main properties of graded extensions to the category of locally compact groupoids endowed with involutions. We introduce Real \v{C}ech cohomology, which is an equivariant-like cohomology theory suitable for the context of ... More

Cognitive Access Protocol for Alleviating Sensing Errors in Cognitive Multiple-Access SystemsOct 29 2016This letter studies a time-slotted multiple-access system with a primary user (PU) and a secondary user (SU) sharing the same channel resource. We propose a novel secondary access protocol which alleviates sensing errors and detects the availability of ... More

Crossed extensions and equivalences of topological 2-groupoidsFeb 06 2018We provide concrete models for generalized morphisms and Morita equivalences of topological 2-groupoids by introducing the notions of crossings and crossed extensions of groupoid crossed modules. A systematic study of these objects is elaborated and an ... More

Cell Associations that Maximize the Average Uplink-Downlink Degrees of FreedomMay 13 2016We study the problem of associating mobile terminals to base stations in a linear interference network, with the goal of maximizing the average rate achieved over both the uplink and downlink sessions. The cell association decision is made at a centralized ... More

Parametric estimation of hidden stochastic model by contrast minimization and deconvolution: application to the Stochastic Volatility ModelFeb 12 2012Mar 14 2013We study a new parametric approach for particular hidden stochastic models such as the Stochastic Volatility model. This method is based on contrast minimization and deconvolution. After proving consistency and asymptotic normality of the estimation leading ... More

Common-Description Learning: A Framework for Learning Algorithms and Generating Subproblems from Few ExamplesMay 01 2016Current learning algorithms face many difficulties in learning simple patterns and using them to learn more complex ones. They also require more examples than humans do to learn the same pattern, assuming no prior knowledge. In this paper, a new learning ... More

Cloud-Based Topological Interference Management: A Case with No Cooperative Transmission GainMay 17 2016We study the problem of managing interference in linear networks, with backhaul constraints that admit centralized allocation of messages to transmitters through the cloud. Our setting is that of a generic channel, where no channel state information is ... More

A non-unital algebra has UUNP iff its unitization has UUNPDec 10 2015Let $A$ be a non-unital Banach algebra, S. J. Bhatt and H. V. Dedania showed that $A$ has the unique uniform norm property (UUNP) if and only if its unitization has UUNP. Here we prove this result for any non-unital algebra.

On saturated uniformly A-convex algebrasJan 07 2013Aug 11 2014Following ideas of A.C.Cochran, we give a suitable definition of a saturated uniformly A-convex algebra. In the m-convex case, such algebra is a uniform topological one.

Positive linear functionals on BP*-algebrasMay 07 2013Apr 12 2015Let A be a BP*-algebra with identity e, P_{1}(A) be the set of all positive linear functionals f on A such that f(e) = 1, and let M_{s}(A) be the set of all nonzero hermitian multiplicative linear functionals on A. We prove that M_{s}(A) is the set of ... More

Counting positive intersection points of a trinomial and a $\mathbf{T}$-nomial curves via Groethendieck's dessin d'enfantDec 17 2015We consider real polynomial systems $f=g=0$ in two variables where $f$ has $t\geq 3$ monomial terms and $g$ has $3$ monomials terms. We prove that the number of positive isolated solutions of such a system does not exceed $3\cdot 2^{t-2} - 1$. This improves ... More

Characterization of circuits supporting polynomial systems with the maximal number of positive solutionsMar 06 2016A polynomial system with $n$ equations in $n$ variables supported on a set $\mathcal{W}\subset\mathbb{R}^n$ of $n+2$ points has at most $n+1$ non-degenerate positive solutions. Moreover, if this bound is reached, then $\mathcal{W}$ is minimally affinely ... More

The (> Half) Empty UniverseApr 02 1997Voids are the most prominent feature of the large-scale structure of the universe. Still, they have been generally ignored in quantitative analysis of it, essentially due to the lack of an objective tool to identify the voids and to quantify them. To ... More

A Mobile Management System for Reforming Subsidies Distribution in Developing CountriesApr 30 2014This paper has a specific objective of being useful for showing how the advances in mobile technologies can help for solving social and political aspects involved in the reform of subsidies in developing countries. It describes the work done to build ... More

Optimal Random Access and Random Spectrum Sensing for an Energy Harvesting Cognitive Radio with and without Primary Feedback LeveragingJan 01 2014Apr 27 2014We consider a secondary user (SU) with energy harvesting capability. We design access schemes for the SU which incorporate random spectrum sensing and random access, and which make use of the primary automatic repeat request (ARQ) feedback. We study two ... More