Random template banks and relaxed lattice coverings

Template-based searches for gravitational waves are often limited by the computational cost associated with searching large parameter spaces. The study of efficient template banks, in the sense of using the smallest number of templates, is therefore of great practical interest. The "traditional" approach to template-bank construction requires every point in parameter space to be covered by at least one template, which rapidly becomes inefficient at higher dimensions. Here we study an alternative approach, where any point in parameter space is covered only with a given probability < 1. We find that by giving up complete coverage in this way, large reductions in the number of templates are possible, especially at higher dimensions. The prime examples studied here are "random template banks", in which templates are placed randomly with uniform probability over the parameter space. In addition to its obvious simplicity, this method turns out to be surprisingly efficient. We analyze the statistical properties of such random template banks, and compare their efficiency to traditional lattice coverings. We further study "relaxed" lattice coverings (using Zn and An* lattices), which similarly cover any signal location only with probability < 1. The relaxed An* lattice is found to yield the most efficient template banks at low dimensions (n < 10), while random template banks increasingly outperform any other method at higher dimensions.Comment: 13 pages, 10 figures, submitted to PR

Data analysis of gravitational-wave signals from spinning neutron stars. V. A narrow-band all-sky search

We present theory and algorithms to perform an all-sky coherent search for periodic signals of gravitational waves in narrow-band data of a detector. Our search is based on a statistic, commonly called the $\mathcal{F}$-statistic, derived from the maximum-likelihood principle in Paper I of this series. We briefly review the response of a ground-based detector to the gravitational-wave signal from a rotating neuron star and the derivation of the $\mathcal{F}$-statistic. We present several algorithms to calculate efficiently this statistic. In particular our algorithms are such that one can take advantage of the speed of fast Fourier transform (FFT) in calculation of the $\mathcal{F}$-statistic. We construct a grid in the parameter space such that the nodes of the grid coincide with the Fourier frequencies. We present interpolation methods that approximately convert the two integrals in the $\mathcal{F}$-statistic into Fourier transforms so that the FFT algorithm can be applied in their evaluation. We have implemented our methods and algorithms into computer codes and we present results of the Monte Carlo simulations performed to test these codes.Comment: REVTeX, 20 pages, 8 figure

Non-marine Paleogene sequences, Salta Group, Northwest Argentina

Los depósitos de edad paleógena forman la culminación de la cuenca distensiva originada desde el Cretácico inferior hasta el Eoceno en el noroeste argentino. El desarrollo del rift presenta extensión regional y abarca parte de la sedimentación ocurrida en forma contemporánea en Bolivia, Paraguay y Chile. Durante el desarrollo de cuenca con subsidencia termal, se formaron tres secuencias deposicionales constituidas por las Formaciones Mealla, Maíz Gordo y Lumbrera, que integran el Subgrupo Santa Bárbara del Grupo Salta. Estas unidades presentan características sedimentológicas similares que le confieren cierta ciclicidad a este período. La distribución de los sedimentos y la asociación de facies del Subgrupo Santa Bárbara señalan una cuenca cerrada con sedimentación aluvial hacia los bordes y formación de lagos en el área central. En la Formación Mealla se han reconocido cuatro asociaciones de facies (FA) que en gran medida identifican los ambientes sedimentarios que la integran. En posiciones de bordes de cuenca, por ejemplo sobre el borde del arco Traspampeano, se han identificado las asociaciones de facies 1 y 2 (FA1 y FA2) formadas por las litofacies Gm, Gt, Gp, Sm, Sp, Sm, Se, Fm, Fl, Fsc y P. Se ha interpretado un ambiente de abanicos aluviales proximales a distales con buen desarrollo de las facies de llanura de inundación y formación de paleosuelos carbonáticos. Hacia el centro de la cuenca se reconoció la asociacion de facies FA 3, integrada por Sp, St, Sr, Fm y P que indican sistemas fluviales arenosos interpretados como ríos entrelazados arenosos y meandrosos de grano fino. La FA 4 representa la deposición en medio subácueo, integrada por las litofacies F, Sw, Cm, E y Bs e interpretada como lago salino a lago abierto de agua dulce. En la Formación Maíz Gordo el esquema es muy similar. Hacia los bordes de cuenca se reconoció la asociación de facies FA5, integrada por las litofacies Gm, Sm, St, Gh, Gp y Sp, e interpretada como abanico aluvial proximal y ríos entrelazados profundos. Lateralmente se reconoció la asociación de facies FA 6, formada por las litofacies Sp, St, Sr, Fm, Fl y P que representa la formación de ríos entrelazados arenosos. En el centro de la cuenca se identificaron las asociaciones de facies FA 7 y FA 8, integradas por las litofacies Fm, Bs, Go, Ll, F, Lwl, Sw y P que indican sedimentación subácuea de tipo lacustre con extensa formación de facies litorales carbonáticas e internas de tipo meromíctico. La Formación Lumbrera representa la culminación de la sedimentación en el Grupo Salta, caracterizada por sedimentación de tipo pelítico y frecuentes paleosuelos carbonáticos en el área con sedimentación aluvial. Está integrada por las asociaciones de facies FA 9, Sp, St, Se, Fm y P e interpretada como ríos meandrosos de arena gruesa, FA 10, Sp, St, Sr, Ss, Se, Sh, Sl, Fl y Fm cuya asociación representa ríos meandrosos finos en los que se distinguen los depósitos de sobrebanco, albardón y desborde. En el centro de la cuenca se reconocieron las FA 11 y FA 12, integradas por las litofacies St, Sr, F, Sw, Fm, Ll y Bs que representan la acumulación en un sistema lacustre clástico de tipos holomíctico y meromíctico. El contenido paleontológico tanto de palinomorfos como de vertebrados revela variaciones climáticas fluctuantes desde situaciones de aridez hasta condiciones de mayor humedad, lo que sustenta las interpretaciones sedimentológicas realizadas. En la base de cada unidad se ha interpretado condiciones de aridez que pasan gradualmente a situaciones de mayor humedad hacia el tope.Deposits of Paleogene age form the culmination of the distensive basin developed from Lower Cretaceous up to Eocene times in North west A rgentina. The rift development shows a regional extension, and includes part of the sedimentation which occurred contemporaneously in Bolivia, Paraguay and Chile. During development of the sag basin, three depositional sequences were laid down. These were the Mealla, Maíz Gordo and Lumbrera Formations, which make up the Santa Bárbara Subgroup of the Salta Group. These units present similar sedimentological characteristics, which gives this period a cyclic arrangement . The sedimentary distribution and the arrangement of facies point to a closed basin, with alluvial sedimentation toward its borders, and the formation of lakes in its central area. Each unit shows a particular pattern of river systems, from perennial sand-gravel bed braided streams to fine-grained meandering streams, and pattern of the lake originated there. It is recognized that each lacustrine basin started to develop under shallow conditions in an arid climate, and then evolved to deeper lakes, which reached stratification of the water mass. The paleontologic content, especially the palinomorphs, records these fluctuating climatic changes, from arid situations to more humid conditions

Correlations in the Sine-Gordon Model with Finite Soliton Density

We study the sine-Gordon (SG) model at finite densities of the topological charge and small SG interaction constant, related to the one-dimensional Hubbard model near half-filling. Using the modified WKB approach, we find that the spectrum of the Gaussian fluctuations around the classical solution reproduces the results of the Bethe ansatz studies. The modification of the collective coordinate method allows us to write down the action, free from infra-red divergencies. The behaviour of the density-type correlation functions is non-trivial and we demonstrate the existence of leading and sub-leading asymptotes. A consistent definition of the charge-raising operator is discussed. The superconducting-type correlations are shown to decrease slowly at small soliton densities, while the spectral weight of right (left) moving fermions is spread over neighboring "4k_F" harmonics.Comment: 12 pages, 3 eps figures, REVTEX; a discussion of fermions is adde

Overcoming the Legacy of Mistrust: African Americans’ Mistrust of Medical Profession

Recent studies show that racism still exists in the American medical profession, the fact of which legitimizes the historically long-legacy of mistrust towards medical profession and health authorities among African Americans. Thus, it was suspected that the participation of black patients in end-of-life care has always been significantly low stemmed primarily from their mistrust of the medical profession. On the other hand, much research finds that there are other reasons than the mistrust which makes African Americans feel reluctant to the end-of-life care, such as cultural-religious difference and genuine misunderstanding of the services. If so, two crucial questions are raised. One is how pervasive or significant the mistrust is, compared to the other factors, when they opt out of the end-of-life care. The other is if there is a remedy or solution to the seemingly broken relationship. While no studies available answer these questions, we have conducted an experiment to explore them. The research was performed at two Philadelphia hospitals of Mercy Health System, and the result shows that Black patients’ mistrust is not too great to overcome and that education can remove the epistemic obstacles as well as overcome the mistrust

Exclusive quasielastic production of dijets at hadronic colliders

We critically re-examine the calculation of central production of dijets in quasi-elastic hadronic collisions. We find that the process is not dominated by the perturbative contribution, and discuss several sources of uncertainties in the calculation.Comment: 4 pages, talk given at Diffraction-2008, La Londe-les-Maures, France, 9-14 Sept 200

EEG-based person identification through binary flower pollination algorithm

Electroencephalogram (EEG) signal presents a great potential for highly secure biometric systems due to its characteristics of universality, uniqueness, and natural robustness to spoofing attacks. EEG signals are measured by sensors placed in various positions of a person’s head (channels). In this work, we address the problem of reducing the number of required sensors while maintaining a comparable performance. We evaluated a binary version of the Flower Pollination Algorithm under different transfer functions to select the best subset of channels that maximizes the accuracy, which is measured by means of the Optimum-Path Forest classifier. The experimental results show the proposed approach can make use of less than a half of the number of sensors while maintaining recognition rates up to 87%, which is crucial towards the effective use of EEG in biometric applications

Scaling Exponents in the Incommensurate Phase of the Sine-Gordon and U(1) Thirring Models

In this paper we study the critical exponents of the quantum sine-Gordon and U(1) Thirring models in the incommensurate phase. This phase appears when the chemical potential $h$ exceeds a critical value and is characterized by a finite density of solitons. The low-energy sector of this phase is critical and is described by the Gaussian model (Tomonaga-Luttinger liquid) with the compactification radius dependent on the soliton density and the sine-Gordon model coupling constant $\beta$. For a fixed value of $\beta$, we find that the Luttinger parameter $K$ is equal to 1/2 at the commensurate-incommensurate transition point and approaches the asymptotic value $\beta^2/8\pi$ away from it. We describe a possible phase diagram of the model consisting of an array of weakly coupled chains. The possible phases are Fermi liquid, Spin Density Wave, Spin-Peierls and Wigner crystal.Comment: 10pages; Improved version; Submitted to Physical Review

Finite-size scaling and the deconfinement transition in gauge theories

We introduce a new method for determining the critical indices of the deconfinement transition in gauge theories. The method is based on the finite size scaling behavior of the expectation value of simple lattice operators, such as the plaquette. We test the method for the case of SU(3) pure gauge theory in (2+1) dimensions and obtain a precise determination of the critical index $\nu$, in agreement with the prediction of the Svetitsky-Yaffe conjecture.Comment: 6 pages. Several comments and one reference added, results unchange

Critical behavior of the compact 3d U(1) theory in the limit of zero spatial coupling

Critical properties of the compact three-dimensional U(1) lattice gauge theory are explored at finite temperatures on an asymmetric lattice. For vanishing value of the spatial gauge coupling one obtains an effective two-dimensional spin model which describes the interaction between Polyakov loops. We study numerically the effective spin model for N_t=1,4,8 on lattices with spatial extension ranging from L=64 to L=256. Our results indicate that the finite-temperature U(1) lattice gauge theory belongs to the universality class of the two-dimensional XY model, thus supporting the Svetitsky-Yaffe conjecture.Comment: 17 pages, 5 figures; two references added, a few comments included, title changed; version to appear on J. Stat. Mec