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Results for "David Jimenez-Cabello"

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Generalized Presentation Attack Detection: a face anti-spoofing evaluation proposalApr 12 2019Over the past few years, Presentation Attack Detection (PAD) has become a fundamental part of facial recognition systems. Although much effort has been devoted to anti-spoofing research, generalization in real scenarios remains a challenge. In this paper ... More
Simple PTAS's for families of graphs excluding a minorOct 21 2014Mar 27 2015We show that very simple algorithms based on local search are polynomial-time approximation schemes for Maximum Independent Set, Minimum Vertex Cover and Minimum Dominating Set, when the input graphs have a fixed forbidden minor.
Deep Anomaly Detection for Generalized Face Anti-SpoofingApr 17 2019Face recognition has achieved unprecedented results, surpassing human capabilities in certain scenarios. However, these automatic solutions are not ready for production because they can be easily fooled by simple identity impersonation attacks. And although ... More
Where are the absorbers towards Q2302+029?Sep 12 2000We present images and spectroscopy of objects close to the sightline of Q2302+029 in order to search for galaxies responsible for the remarkable z=0.7 high-ionization absorption line system found by Jannuzi et al (1996). This system shows `normal' narrow ... More
Quiz your maths: do the uniformly continuous functions on the line form a ring?Jan 04 2019Jan 08 2019The paper deals with the interplay between boundedness, order and ring structures in function lattices on the line and related metric spaces. It is shown that the lattice of all Lipschitz functions on a normed space $E$ is isomorphic to its sublattice ... More
A reflection on Tingley's problem and some applicationsOct 04 2018In this paper we show how some metric properties of the unit sphere of a normed space can help to approach a solution to Tingley's problem. In our main result we show that if an onto isometry between the spheres of strictly convex spaces is the identity ... More
When is U(X) a ring?Mar 21 2017In this short paper, we will show that the space of real valued uniformly continuous functions defined on a metric space $(X,d)$ is a ring if and only if every subset $A\subset X$ has one of the following properties: $A$ is Bourbaki-bounded, i.e., every ... More
A reflection on Tingley's problem and some applicationsOct 04 2018Mar 20 2019In this paper we show how some metric properties of the unit sphere of a normed space can help to approach a solution to Tingley's problem. In our main result we show that if an onto isometry between the spheres of strictly convex spaces is the identity ... More
Improving Photometric Redshifts using GALEX Observations for the SDSS Stripe 82 and the Next Generation of SZ Cluster SurveysMar 21 2008Four large-area Sunyaev-Zeldovich (SZ) experiments -- APEX-SZ, SPT, ACT, and Planck -- promise to detect clusters of galaxies through the distortion of Cosmic Microwave Background photons by hot (> 10^6 K) cluster gas (the SZ effect) over thousands of ... More
A 6% measurement of the Hubble parameter at $z\sim0.45$: direct evidence of the epoch of cosmic re-accelerationJan 07 2016May 02 2016Deriving the expansion history of the Universe is a major goal of modern cosmology. To date, the most accurate measurements have been obtained with Type Ia Supernovae and Baryon Acoustic Oscillations, providing evidence for the existence of a transition ... More
Southern Cosmology Survey III: QSO's from Combined GALEX and Optical PhotometryNov 25 2008We present catalogs of QSO candidates selected using photometry from GALEX combined with SDSS in the Stripe 82 region and Blanco Cosmology Survey (BCS) near declination -55 degrees. The SDSS region contains ~700 objects with magnitude i < 20 and ~3600 ... More
Drift-diffusion model for single layer transition metal dichalcogenide field-effect transistorsJul 12 2012A physics-based model for the surface potential and drain current for monolayer transition metal dichalcogenide (TMD) field-effect transistor (FET) is presented. Taking into account the 2D density-of-states of the atomic layer thick TMD and its impact ... More
A current-voltage model for Schottky-barrier graphene based transistorsDec 11 2007Jul 15 2008A low complexity computational model of the current-voltage characteristics for graphene nano-ribbon (GNR) field effect transistors (FET), able to simulate a hundred of points in few seconds using a PC, is presented. For quantum capacitance controlled ... More
Measurements of minimum entropy at K-shell photoelectric effect provides the radius and shape of the protonJan 04 2017Jan 12 2017Constructive resonances with minimum entropy are derived from measurements of photoelectric effect cross sections at atomic K-shell thresholds. A resonance region with optimal constructive interference is given by a principal wave length {\lambda} of ... More
The Hölder exponent of some Fourier seriesApr 20 2015In this paper we study the local regularity of fractional integrals of Fourier series using several definitions of the H\"older exponent. We especially consider series coming from fractional integrals of modular forms. Our results show that in general ... More
Reconciling the GRB rate and star formation historiesMar 20 2013Jun 12 2013While there are numerous indications that GRBs arise from the death of massive stars, the GRB rate does not follow the global cosmic star formation rate and, within their hosts, GRBs are more concentrated in regions of very high star formation. We explain ... More
Implications for Primordial Non-Gaussianity (f_NL) from weak lensing masses of high-z galaxy clustersSep 02 2009The recent weak lensing measurement of the dark matter mass of the high-redshift galaxy cluster XMMUJ2235.3-2557 of (8.5 +- 1.7) x 10^{14} Msun at z=1.4, indicates that, if the cluster is assumed to be the result of the collapse of dark matter in a primordial ... More
The parameter space of Cubic Galileon models for cosmic accelerationJun 05 2013Nov 19 2013We use recent measurements of the expansion history of the universe to place constraints on the parameter space of cubic Galileon models, in particular we concentrate on those models which contain the simplest Galileon term plus a linear potential. This ... More
On the discretization of nonholonomic dynamics in $\mathbb{R}^n$Jul 08 2014In this paper we explore the nonholonomic Lagrangian setting of mechanical systems in local coordinates on finite-dimensional configuration manifolds. We prove existence and uniqueness of solutions by reducing the basic equations of motion to a set of ... More
On arithmetic progressions on Edwards curvesApr 16 2013Apr 07 2015Let m be a positive integer and a,q two rational numbers. Denote by AP_m(a,q) the set of rational numbers d such that a,a+q,...,a+(m-1)q form an arithmetic progression in the Edwards curve E_d:x^2+y^2=1+d x^2 y^2. We study the set AP_m(a,q) and we parametrize ... More
Approximate discrete-time schemes for the estimation of diffusion processes from complete observationsDec 08 2012Dec 18 2013In this paper, a modification of the conventional approximations to the quasi-maximum likelihood method is introduced for the parameter estimation of diffusion processes from discrete observations. This is based on a convergent approximation to the first ... More
On sets defining few ordinary solidsAug 20 2018Let $\mathcal{S}$ be a set of $n$ points in real four-dimensional space, no four coplanar and spanning the whole space. We prove that if the number of solids incident with exactly four points of $\mathcal{S}$ is less than $Kn^3$ for some $K=o(n^{\frac{1}{7}})$ ... More
Explicit drain-current model of graphene field-effect transistors targeting analog and radio-frequency applicationsMar 08 2011Jun 24 2011We present a compact physics-based model of the current-voltage characteristics of graphene field-effect transistors, of especial interest for analog and radio-frequency applications where bandgap engineering of graphene could be not needed. The physical ... More
Rolle's theorem is either false or trivial in infinite-dimensional Banach spacesFeb 14 2000We prove the following new characterization of $C^p$ (Lipschitz) smoothness in Banach spaces. An infinite-dimensional Banach space $X$ has a $C^p$ smooth (Lipschitz) bump function if and only if it has another $C^p$ smooth (Lipschitz) bump function $f$ ... More
Convergence rate of weak Local Linearization schemes for stochastic differential equations with additive noiseDec 20 2013There exists a diversity of weak Local Linearization (LL) schemes for the integration of stochastic differential equations with additive noise, which differ with respect to the algorithm that is employed in the numerical implementation of the weak Local ... More
Quasi-Banach spaces of almost universal dispositionSep 29 2013Apr 30 2014We show that for each $p\in(0,1]$ there exists a separable $p$-Banach space $\mathbb G_p$ of almost universal disposition, that is, having the following extension property: for each $\epsilon>0$ and each isometric embedding $g:X\to Y$, where $Y$ is a ... More
Modeling the EM Field Distribution within a Computer Chip PackageSep 05 2018Wireless Network-on-Chip (WNoC) appears as a promising alternative to conventional interconnect fabrics for chip-scale communications. The study of the channel inside the chip is essential to minimize latency and power. However, this requires long and ... More
Minimum detection efficiency for a loophole-free violation of the Braunstein-Caves chained Bell inequalitiesApr 06 2009Jun 23 2009The chained Bell inequalities of Braunstein and Caves involving N settings per observer have some interesting applications. Here we obtain the minimum detection efficiency required for a loophole-free violation of the Braunstein-Caves inequalities for ... More
Necessary and sufficient detection efficiency for the Mermin inequalitiesDec 19 2007Sep 16 2008We prove that the threshold detection efficiency for a loophole-free Bell experiment using an $n$-qubit Greenberger-Horne-Zeilinger state and the correlations appearing in the $n$-partite Mermin inequality is $n/(2n-2)$. If the detection efficiency is ... More
Parameterized Complexity of 1-PlanarityApr 20 2013We consider the problem of finding a 1-planar drawing for a general graph, where a 1-planar drawing is a drawing in which each edge participates in at most one crossing. Since this problem is known to be NP-hard we investigate the parameterized complexity ... More
Addendum to "Experimental demonstration of a quantum protocol for Byzantine agreement and liar detection" arXiv:0710.0290Oct 21 2008Nov 16 2008Gao et al. [Phys. Rev. Lett. 101, 208901 (2008)] have described a possible intercept-resend attack for the quantum protocol for detectable Byzantine agreement in Phys. Rev. Lett. 100, 070504 (2008). Here we describe an extension of the protocol which ... More
Minimal true-implies-false and true-implies-true sets of propositions in noncontextual hidden variable theoriesMay 02 2018Jul 09 2018An essential ingredient in many examples of the conflict between quantum theory and noncontextual hidden variables (e.g., the proof of the Kochen-Specker theorem and Hardy's proof of Bell's theorem) is a set of atomic propositions about the outcomes of ... More
Seven views on approximate convexity and the geometry of K-spacesMay 13 2005As in Hokusai's series of paintings "Thirty six views of mount Fuji" in which mount Fuji's is sometimes scarcely visible, the central topic of this paper is the geometry of $K$-spaces although in some of the seven views presented $K$-spaces are not easily ... More
Mermin inequalities for perfect correlationsAug 23 2007Jun 16 2008Any n-qubit state with n independent perfect correlations is equivalent to a graph state. We present the optimal Bell inequalities for perfect correlations and maximal violation for all classes of graph states with n < 7 qubits. Twelve of them were previously ... More
The Fibonacci dimension of a graphMar 13 2009The Fibonacci dimension fdim(G) of a graph G is introduced as the smallest integer f such that G admits an isometric embedding into Gamma_f, the f-dimensional Fibonacci cube. We give bounds on the Fibonacci dimension of a graph in terms of the isometric ... More
Square-free discriminants of Frobenius ringsMay 06 2008Let $E$ be an elliptic curve over $\Q$. It is well known that the ring of endomorphisms of $E_p$, the reduction of $E$ modulo a prime $p$ of ordinary reduction, is an order of the quadratic imaginary field $Q(\pi_p)$ generated by the Frobenius element ... More
Does stellar mass assembly history vary with environment?Jan 28 2011Using the publicly available VESPA database of SDSS Data Release 7 spectra, we calculate the stellar Mass Weighted Age (hereafter MWA) as a function of local galaxy density and dark matter halo mass. We compare our results with semi-analytic models from ... More
A Halo Model with Environment Dependence: Theoretical ConsiderationsAug 26 2010Feb 02 2011We present a modification of the standard halo model with the goal of providing an improved description of galaxy clustering. Recent surveys, like the Sloan Digital Sky Survey (SDSS) and the Anglo-Australian Two-degree survey (2dF), have shown that there ... More
An effective theory of accelerated expansionJul 13 2011Nov 16 2012We work out an effective theory of accelerated expansion to describe general phenomena of inflation and acceleration (dark energy) in the Universe. Our aim is to determine from theoretical grounds, in a physically-motivated and model independent way, ... More
Revisiting the effect of H2, HD and LiH molecules in the cooling of primordial gasSep 16 2008Feb 13 2009We use a non-equilibrium chemical network to revisit and study the effect of H_{2}, HD and LiH molecular cooling on a primordial element of gas. We solve both the thermal and chemical equations for a gas element with an initial temperature T\approx 1000K ... More
The luminosity and stellar mass functions of GRB host galaxies: Insight into the metallicity biasJun 05 2014Jan 27 2015Long-Duration Gamma-Ray Bursts (GRBs) are powerful probes of the Universe star formation history, but correlation between the two depends on the highly debated presence/strength of a metallicity bias. To investigate this correlation, we use a phenomenological ... More
Light Higgs Boson Production in Two Higgs Doublets Models type IIIOct 23 2008By using the Cheng, Sher and Yuan's anzats, we study the light Higgs Boson production associated with $b$ quark production at TEVATRON using the 2HDM type III. We compare the simulations with experimental results coming from TEVATRON, finding valid ranges ... More
Wide binaries as a critical test for Gravity theoriesMay 25 2012Assuming Newton's gravity and GR to be valid at all scales leads to the dark matter hypothesis as a requirement demanded by the observed dynamics and measured baryonic content at galactic and extragalactic scales. Alternatively, modified gravity scenarios ... More
Variational Intrinsic ControlNov 22 2016In this paper we introduce a new unsupervised reinforcement learning method for discovering the set of intrinsic options available to an agent. This set is learned by maximizing the number of different states an agent can reliably reach, as measured by ... More
Sharp affine Sobolev type inequalities via the $\Lp$ Busemann-Petty centroid inequalityMay 28 2015Mar 29 2016We show that the $\Lp$ Busemann-Petty centroid inequality provides an elementary and powerful tool to the study of some sharp affine functional inequalities with a geometric content, like log-Sobolev, Sobolev and Gagliardo-Nirenberg inequalities. Our ... More
Geometric-based Line Segment Tracking for HDR Stereo SequencesSep 25 2018In this work, we propose a purely geometrical approach for the robust matching of line segments for challenging stereo streams with severe illumination changes or High Dynamic Range (HDR) environments. To that purpose, we exploit the univocal nature of ... More
Planck and the local Universe: quantifying the tensionJun 28 2013We use the latest Planck constraints, and in particular constraints on the derived parameters (Hubble constant and age of the Universe) for the local universe and compare them with local measurements of the same quantities. We propose a way to quantify ... More
Testing homogeneity with the fossil record of galaxiesJul 29 2011Sep 15 2011The standard Friedmann model of cosmology is based on the Copernican Principle, i.e. the assumption of a homogeneous background on which structure forms via perturbations. Homogeneity underpins both general relativistic and modified gravity models and ... More
Phenomenology of the minimal inflation scenario: inflationary trajectories and particle productionOct 18 2011Mar 06 2012We discuss the phenomenology of the minimal inflation scenario. We concentrate on two aspects: inflationary trajectories and particle production. Our findings can be summarized in two main results: first, that inflationary trayectories that are very flat ... More
Dark matter merging induced turbulence as an efficient engine for gas coolingAug 02 2011Sep 30 2011We have performed a cosmological numerical simulation of primordial baryonic gas collapsing onto a $3\times10^7$M$_{\odot}$ dark matter (DM) halo. We show that the large scale baryonic accretion process and the merger of few $\sim10^6$ M$_{\odot}$ DM ... More
The Void Abundance with Non-Gaussian Primordial PerturbationsSep 03 2008We use a Press-Schechter-like calculation to study how the abundance of voids changes in models with non-Gaussian initial conditions. While a positive skewness increases the cluster abundance, a negative skewness does the same for the void abundance. ... More
Minimal InflationDec 30 2009Using the universal X superfield that measures in the UV the violation of conformal invariance we build up a model of multifield inflation. The underlying dynamics is the one controlling the natural flow of this field in the IR to the Goldstino superfield ... More
Standard rulers, candles, and clocks from the low-redshift UniverseSep 22 2014Nov 18 2014We measure the length of the Baryon Acoustic Oscillation (BAO) feature, and the expansion rate of the recent Universe, from low-redshift data only, almost model-independently. We make only the following minimal assumptions: homogeneity and isotropy; a ... More
The expansion rate of the intermediate Universe in light of PlanckMar 10 2014We use cosmology-independent measurements of the expansion history in the redshift range 0.1 < z <1.2 and compare them with the Cosmic Microwave Background-derived expansion history predictions. The motivation is to investigate if the tension between ... More
Isothermal distributions in MONDian gravity as a simple unifying explanation for the ubiquitous $ρ\propto r^{-3}$ density profiles in tenuous stellar halosDec 03 2012Apr 11 2013That the stellar halo of the Milky Way has a density profile which to first approximation satisfies $\rho \propto r^{-3}$ has been known for a long time. More recently, it has become clear that M31 also has such an extended stellar halo, which approximately ... More
A weak Local Linearization scheme for stochastic differential equations with multiplicative noiseJun 18 2015In this paper, a weak Local Linearization scheme for Stochastic Differential Equations (SDEs) with multiplicative noise is introduced. First, for a time discretization, the solution of the SDE is locally approximated by the solution of the piecewise linear ... More
Slopes of a Hypergeometric System Associated to a Monomial CurveJul 06 2001We compute, by D-module restrictions, the slopes of irregular hypergeometric systems associated to a monomial curve.
Asymmetric Blaschke-Santaló functional inequalitiesOct 04 2018In this work we establish functional asymmetric versions of the celebrated Blaschke-Santal\'o inequality. As consequences of these inequalities we recover their geometric counterparts with equality cases, as well as, another inequality with strong probabilistic ... More
Optimal transportation with traffic congestion and Wardrop equilibriaDec 22 2006In the classical Monge-Kantorovich problem, the transportation cost only depends on the amount of mass sent from sources to destinations and not on the paths followed by this mass. Thus, it does not allow for congestion effects. Using the notion of traffic ... More
Neutrino footprint in Large Scale StructureFeb 26 2016Recent constrains on the sum of neutrino masses inferred by analyzing cosmological data, show that detecting a non-zero neutrino mass is within reach of forthcoming cosmological surveys, implying a direct determination of the absolute neutrino mass scale. ... More
Gas infall into atomic cooling haloes: on the formation of protogalactic disks and supermassive black holes at z > 10Jan 23 2013We have performed cosmo-hydro simulations using the RAMSES code to study atomic cooling (ACHs) haloes at z=10 with masses 5E7Msun<~M<~2E9Msun. We assume primordial gas and H2-cooling and prior star-formation have been suppressed. We analysed 19 haloes ... More
Effects of the neutrino mass splitting on the non-linear matter power spectrumMar 23 2012We have performed cosmological N-body simulations which include the effect of the masses of the individual neutrino species. The simulations were aimed at studying the effect of different neutrino hierarchies on the matter power spectrum. Compared to ... More
Consistency among distance measurements: transparency, BAO scale and accelerated expansionFeb 12 2009Jun 11 2009We explore consistency among different distance measures, including Supernovae Type Ia data, measurements of the Hubble parameter, and determination of the Baryon acoustic oscillation scale. We present new constraints on the cosmic transparency combining ... More
Wide binaries as a critical test of Classical GravityMay 10 2011Feb 03 2012Modified gravity scenarios where a change of regime appears at acceleration scales $a<a_{0}$ have been proposed. Since for $1 M_{\odot}$ systems the acceleration drops below $a_{0}$ at scales of around 7000 AU, a statistical survey of wide binaries with ... More
Flattened velocity dispersion profiles in Globular Clusters: Newtonian tides or modified gravity?Jun 21 2012Oct 22 2012Over the past couple of years, a number of observational studies have confirmed the flattening of the radial velocity dispersion profiles for stars in various nearby globular clusters. As the projected radial coordinate is increased, a radius appears ... More
Homogenising differential operatorsNov 08 2012We consider the Weyl algebra A (=A_n(k)) and its Rees algebra B with respect to the Bernstein filtration. The homogenisation of a differential operator in A is an element in B. In this paper we establish the validity of the division theorem for homogenized ... More
Robust self-testing of quantum systems via noncontextuality inequalitiesDec 18 2018Dec 20 2018Self-testing unknown quantum states and measurements is a fundamental problem in quantum information processing. Here, we introduce an approach for studying this problem via the use of noncontextuality inequalities. We show that the celebrated Klyachko-Can-Binicio\ifmmode ... More
On the origin of Damped Lyman-alpha systems: a case for LSB galaxies?Dec 02 1998We use a model of galaxy disk formation to explore the metallicities, dust content, and neutral-gas mass density of damped Lyman-$\alpha$ (D\lya) absorbers. We find that the [Zn/H] abundance measurements of D\lya systems now available can be reproduced ... More
A New Algorithm to Fit Exponential DecaysNov 21 2017This paper deals with some nonlinear problems which exponential and biexponential decays are involved in. A proof of the quasiconvexity of the error function in some of these problems of optimization is presented. This proof is restricted to fitting observations ... More
The AOLI low-order non-linear curvature wavefront sensor: a method for high sensitivity wavefront reconstructionJul 04 2012The Adaptive Optics Lucky Imager (AOLI) is a new instrument under development to demonstrate near diffraction limited imaging in the visible on large ground-based telescopes. We present the adaptive optics system being designed for the instrument comprising ... More
AOLI-- Adaptive Optics Lucky Imager: Diffraction Limited Imaging in the Visible on Large Ground-Based TelescopesJul 17 2012The highest resolution images ever taken in the visible were obtained by combining Lucky Imaging and low order adaptive optics. This paper describes a new instrument to be deployed on the WHT 4.2m and GTC 10.4 m telescopes on La Palma, with particular ... More
Structure of Small Magnetic Elements in the Solar AtmosphereSep 05 2012High resolution images at different wavelengths, spectrograms and magnetograms, representing different levels of the solar atmosphere obtained with Hinode have been combined to study the 3-dimensional structure of the small magnetic elements in relation ... More
Evolution of small-scale magnetic elements in the vicinity of granular-size swirl convective motionsMay 10 2014Advances in solar instrumentation have led to a widespread usage of time series to study the dynamics of solar features, specially at small spatial scales and at very fast cadences. Physical processes at such scales are determinant as building blocks ... More
Annotating Simplices with a Homology Basis and Its ApplicationsJul 19 2011May 18 2012Let $K$ be a simplicial complex and $g$ the rank of its $p$-th homology group $H_p(K)$ defined with $Z_2$ coefficients. We show that we can compute a basis $H$ of $H_p(K)$ and annotate each $p$-simplex of $K$ with a binary vector of length $g$ with the ... More
Applying the simplest Kochen-Specker set for quantum information processingAug 28 2014Kochen-Specker (KS) sets are key tools for proving some fundamental results in quantum theory and also have potential applications in quantum information processing. However, so far, their intrinsic complexity has prevented experimentalists from using ... More
Analytic model for the surface potential and drain current in negative capacitance field-effect transistorsMar 31 2010In 2008, Salahuddin and Datta proposed that a ferroelectric material operating in the negative capacitance region could act as a step-up converter of the surface potential in a MOS structure, opening a new route for the realization of transistors with ... More
Energetics of Gamma Ray BurstsMar 16 2001We determine the distribution of total energy emitted by gamma-ray bursts for bursts with fluences and distance information. Our core sample consists of eight bursts with BATSE spectra and spectroscopic redshifts. We extend this sample by adding four ... More
Approximation of integration maps of vector measures and limit representations of Banach function spacesApr 21 2017We study when the integration maps of vector measures can be computed as pointwise limits of their finite rank Radon-Nikod\'ym derivatives. We will show that this can sometimes be done, but there are also principal cases in which this cannot be done. ... More
On the signatures of flare-induced global waves in the Sun: GOLF and VIRGO observationsOct 17 2017Recently, several efforts have been made to identify the seismic signatures of flares and magnetic activity in the Sun and Sun-like stars. In this work, we have analyzed the disk-integrated velocity and intensity observations of the Sun obtained from ... More
An alternative to continuous univariate distributions supported on a bounded interval: The BMT distributionSep 16 2017In this paper, we introduce the BMT distribution as an unimodal alternative to continuous univariate distributions supported on a bounded interval. The ideas behind the mathematical formulation of this new distribution come from computer aid geometric ... More
Stellar indices and kinematics in Seyfert 1 nucleiMay 12 2000We present spectra of 6 type 1 Seyfert galaxies, 2 Seyfert 2, a starburst galaxy and a compact narrow line radiogalaxy, taken in two spectral ranges centered around the near--IR CaII triplet (CaT) (at ~8600 Angstroms), and the Mgb stellar feature at 5180 ... More
The infinitely many zeros of stochastic coupled oscillators driven by random forcesMay 16 2017In this work, previous results concerning the infinitely many zeros of single stochastic oscillators driven by random forces are extended to the general class of coupled stochastic oscillators. We focus on three main subjects: 1) the analysis of this ... More
A critical analysis of high-redshift, massive galaxy clusters: IAug 27 2011Jan 16 2012We critically investigate current statistical tests applied to high redshift clusters of galaxies in order to test the standard cosmological model and describe their range of validity. We carefully compare a sample of high-redshift, massive, galaxy clusters ... More
Pop. III stars from turbulent fragmentation at redshift ~ 11Jan 26 2011We report results from a cosmological simulation with non-equilibrium chemistry of 21 species, including H2, HD, and LiH molecular cooling. Starting from cosmological initial conditions, we focus on the evolution of the central 1.8 Kpc region of a 3 x ... More
Constraining the expansion rate of the Universe using low-redshift ellipticals as cosmic chronometersOct 05 2010Mar 28 2011We present a new methodology to determine the expansion history of the Universe analyzing the spectral properties of early type galaxies (ETG). We found that for these galaxies the 4000\AA break is a spectral feature that correlates with the relative ... More
Relation between halo spin and cosmic web filaments at z=3Jun 14 2016Nov 04 2016We investigate the spin evolution of dark matter haloes and their dependence on the number of connected filaments from the cosmic web at high redshift (spin-filament relation hereafter). To this purpose, we have simulated $5000$ haloes in the mass range ... More
Mild quasi-local non-Gaussianity as a signature of modified gravity during inflationJul 24 2014We show that modifications of Einstein gravity during inflation could leave potentially measurable imprints on cosmological observables in the form of non-Gaussian perturbations. This is due to the fact that these modifications appear in the form of an ... More
Measuring the Energy Scale of Inflation with Large Scale StructuresSep 19 2018Nov 26 2018The determination of the inflationary energy scale represents one of the first step towards the understanding of the early Universe physics. The (very mild) non-Gaussian signals that arise from any inflation model carry information about the energy scale ... More
The length of the low-redshift standard rulerJul 18 2016Assuming the existence of standard rulers, standard candles and standard clocks, requiring only the cosmological principle, a metric theory of gravity, a smooth expansion history, and using state-of-the-art observations, we determine the length of the ... More
Spontaneous formation of vector vortex beams in vertical-cavity surface-emitting lasers with feedbackJun 16 2017The spontaneous emergence of vector vortex beams with non-uniform polarization distribution is reported in a vertical-cavity surface-emitting laser (VCSEL) with frequency-selective feedback. Antivortices with a hyperbolic polarization structure and radially ... More
Population inversion of a NAHS mixture adsorbed into a cylindrical poreSep 13 2007Nov 19 2008A cylindrical nanopore immersed in a non-additive hard sphere binary fluid is studied by means of integral equation theories and Monte Carlo simulations. It is found that at low and intermediate values of the bulk total number density the more concentrated ... More
Gevrey solutions of the irregular hypergeometric system associated with an affine monomial curveNov 20 2008We describe the Gevrey series solutions at singular points of the irregular hypergeometric system (GKZ system) associated with an affine monomial curve. We also describe the irregularity complex of such a system with respect to its singular support. We ... More
Robust Neutrino Constraints by Combining Low Redshift Observations with the CMBOct 01 2009Dec 13 2010We illustrate how recently improved low-redshift cosmological measurements can tighten constraints on neutrino properties. In particular we examine the impact of the assumed cosmological model on the constraints. We first consider the new HST H0 = 74.2 ... More
The origin of spin in galaxies: clues from simulations of atomic cooling halosOct 14 2014In order to elucidate the origin of spin in both dark matter and baryons in galaxies, we have performed hydrodynamical simulations from cosmological initial conditions. We study atomic cooling haloes in the redshift range $100 > z > 9$ with masses of ... More
Gevrey solutions of irregular hypergeometric systems in two variablesNov 20 2008We describe the Gevrey series solutions at singular points of the irregular hypergeometric system (GKZ system) associated with an affine plane monomial curve. We also describe the irregularity complex of such a system with respect to its singular support. ... More
Fragmentation of Molecular Clumps and Formation of ProtoclusterMar 10 2015Sufficiently massive clumps of molecular gas collapse under self-gravity and fragment to spawn a cluster of stars that have a range of masses. We investigate observationally the early stages of formation of a stellar cluster in a massive filamentary infrared ... More
On the consistency of universally non-minimally coupled $f(R,T,R_{μν}T^{μν})$ theoriesNov 06 2014May 14 2015We discuss the consistency of a recently proposed class of theories described by an arbitrary function of the Ricci scalar, the trace of the energy-momentum tensor and the contraction of the Ricci tensor with the energy-momentum tensor. We briefly discuss ... More
Characterization of a Banach-Finsler manifold in terms of the algebras of smooth functionsAug 26 2011In this note we give sufficient conditions to ensure that the weak Finsler structure of a complete $C^k$ Finsler manifold $M$ is determined by the normed algebra $C_b^k(M)$ of all real-valued, bounded and $C^k$ smooth functions with bounded derivative ... More
The stellar evolution of Luminous Red Galaxies, and its dependence on colour, redshift, luminosity and modellingNov 10 2010We present a series of colour evolution models for Luminous Red Galaxies (LRGs) in the 7th spectroscopic data release of the Sloan Digital Sky Survey (SDSS), computed using the full-spectrum fitting code VESPA on high signal-to-noise stacked spectra. ... More
Can we measure the neutrino mass hierarchy in the sky?Mar 30 2010Cosmological probes are steadily reducing the total neutrino mass window, resulting in constraints on the neutrino-mass degeneracy as the most significant outcome. In this work we explore the discovery potential of cosmological probes to constrain the ... More