Non-Gaussian Geostatistical Modeling using (skew) t Processes

We propose a new model for regression and dependence analysis when addressing spatial data with possibly heavy tails and an asymmetric marginal distribution. We first propose a stationary process with $t$ marginals obtained through scale mixing of a Gaussian process with an inverse square root process with Gamma marginals. We then generalize this construction by considering a skew-Gaussian process, thus obtaining a process with skew-t marginal distributions. For the proposed (skew) $t$ process we study the second-order and geometrical properties and in the $t$ case, we provide analytic expressions for the bivariate distribution. In an extensive simulation study, we investigate the use of the weighted pairwise likelihood as a method of estimation for the $t$ process. Moreover we compare the performance of the optimal linear predictor of the $t$ process versus the optimal Gaussian predictor. Finally, the effectiveness of our methodology is illustrated by analyzing a georeferenced dataset on maximum temperatures in Australi

How can we all help conserve nature?

When we speak about conserving nature, we are really talking about taking care of our future, because nature provides essential resources for our survival and enjoyment. We asked an international group of scientists working on different environmental issues worldwide to identify important practical actions that we can all do to help conserve nature. We obtained nearly 100 responses and grouped them into three main categories: (1) Actions to reduce our ecological footprint; (2) Actions to conserve nature; and (3) Actions that help us connect with nature. We briefly explain actions that can be performed daily to reduce our impact on nature, and provide some useful links for further readin

The Early Palomar Program (1950-1955) for the Discovery of Classical Novae in M81: Analysis of the Spatial Distribution, Magnitude Distribution, and Distance Suggestion

Data obtained in the 1950-1955 Palomar campaign for the discovery of classical novae in M81 are set out in detail. Positions and apparent B magnitudes are listed for the 23 novae that were found. There is modest evidence that the spatial distribution of the novae does not track the B brightness distribution of either the total light or the light beyond an isophotal radius that is 70\arcsec from the center of M81. The nova distribution is more extended than the aforementioned light, with a significant fraction of the sample appearing in the outer disk/spiral arm region. We suggest that many (perhaps a majority) of the M81 novae that are observed at any given epoch (compared with say $10^{10}$ years ago) are daughters of Population I interacting binaries. The conclusion that the present day novae are drawn from two population groups, one from low mass white dwarf secondaries of close binaries identified with the bulge/thick disk population, and the other from massive white dwarf secondaries identified with the outer thin disk/spiral arm population, is discussed. We conclude that the M81 data are consistent with the two population division as argued previously from (1) the observational studies on other grounds by Della Valle et al. (1992, 1994), Della Valle & Livio (1998), and Shafter et al. (1996) of nearby galaxies, (2) the Hatano et al. (1997a,b) Monte Carlo simulations of novae in M31 and in the Galaxy, and (3) the Yungelson et al. (1997) population synthesis modeling of nova binaries. Two different methods of using M81 novae as distance indicators give a nova distance modulus for M81 as $(m-M)_0 = 27.75$, consistent with the Cepheid modulus that is the same value.Comment: 24 pages, 7 figures, accepted to PAS

Comparação de três métodos de extração de DNA genômico para análises moleculares em Stylosanthes guianensis.

O objetivo deste trabalho foi comparar a quantidade e qualidade do DNA isolado de folhas de S. guianensis pelos métodos de Bonato et al. (2002), de Faleiro et al. (2003) e um método baseado no de Bonato et al. (2002), mas com modificações que resultem um DNA mais puro e em quantidade suficiente para execução de diversas análises moleculares, incluindo amplificação, clonagem e sequenciamento.bitstream/CNPGC-2010/13216/1/CT36.pd

Defective transport properties of three-terminal carbon nanotube junctions

We investigate the transport properties of three terminal carbon based nanojunctions within the scattering matrix approach. The stability of such junctions is subordinated to the presence of nonhexagonal arrangements in the molecular network. Such "defective" arrangements do influence the resulting quantum transport observables, as a consequence of the possibility of acting as pinning centers of the correspondent wavefunction. By investigating a fairly wide class of junctions we have found regular mutual dependencies between such localized states at the carbon network and a strikingly behavior of the conductance. In particular, we have shown that Fano resonances emerge as a natural result of the interference between defective states and the extended continuum background. As a consequence, the currents through the junctions hitting these resonant states might experience variations on a relevant scale with current modulations of up to 75%.Comment: 8 pages, 8 figure

AE Aurigae: first detection of non-thermal X-ray emission from a bow shock produced by a runaway star

Runaway stars produce shocks when passing through interstellar medium at supersonic velocities. Bow shocks have been detected in the mid-infrared for several high-mass runaway stars and in radio waves for one star. Theoretical models predict the production of high-energy photons by non-thermal radiative processes in a number sufficiently large to be detected in X-rays. To date, no stellar bow shock has been detected at such energies. We present the first detection of X-ray emission from a bow shock produced by a runaway star. The star is AE Aur, which was likely expelled from its birthplace by the encounter of two massive binary systems and now is passing through the dense nebula IC 405. The X-ray emission from the bow shock is detected at 30" to the northeast of the star, coinciding with an enhancement in the density of the nebula. From the analysis of the observed X-ray spectrum of the source and our theoretical emission model, we confirm that the X-ray emission is produced mainly by inverse Compton upscattering of infrared photons from dust in the shock front.Comment: Accepted for publication in the Astrophysical Journal with number ApJ, 757, L6. Four figure

Demodulation of Spatial Carrier Images: Performance Analysis of Several Algorithms Using a Single Image

http://link.springer.com/article/10.1007%2Fs11340-013-9741-6#Optical full-field techniques have a great importance in modern experimental mechanics. Even if they are reasonably spread among the university laboratories, their diffusion in industrial companies remains very narrow for several reasons, especially a lack of metrological performance assessment. A full-field measurement can be characterized by its resolution, bias, measuring range, and by a specific quantity, the spatial resolution. The present paper proposes an original procedure to estimate in one single step the resolution, bias and spatial resolution for a given operator (decoding algorithms such as image correlation, low-pass filters, derivation tools ...). This procedure is based on the construction of a particular multi-frequential field, and a Bode diagram representation of the results. This analysis is applied to various phase demodulating algorithms suited to estimate in-plane displacements.GDR CNRS 2519 “Mesures de Champs et Identification en Mécanique des Solide

Neutrino Electron Scattering and Electroweak Gauge Structure: Future Tests

Low-energy high-resolution neutrino-electron scattering experiments may play an important role in testing the gauge structure of the electroweak interaction. We propose the use of radioactive neutrino sources (e.g. $^{51}$Cr) in underground experiments such as BOREXINO, HELLAZ and LAMA. As an illustration, we display the sensitivity of these detectors in testing the possible existence of extra neutral gauge bosons, both in the framework of E_6 models and of models with left-right symmetry.Comment: 22 pages, revtex, 4 figures included, accepted for publication in Phys. Rev.

Variação sazonal das proteínas do plama seminal de caprinos (Capra hircus) da raça Moxotó.

Resumo: Fatores climáticos, como as altas temperaturas ambientais no semiárido do Nordeste, podem influenciar a atividade reprodutiva do macho caprino. Sabe-se que nessa espécie, a sazonalidade reprodutiva é uma característica importante na limitação da produtividade. Dentre as raças caprinas, a Moxotó representa valioso material genético, pois se caracteriza como animais altamente adaptados ao clima tropical. O estudo de componentes do plasma seminal representa uma alternativa para avaliar o desempenho reprodutivo, através do conhecimento de fatores que interferem diretamente no processo de fertilização, podendo vir a ser considerados como biomarcadores. Estudos têm demonstrado que as proteínas do plasma seminal participam da regulação de diversos processos associados à fisiologia reprodutiva. Este trabalho teve como objetivo identificar as variações do perfil protéico em diferentes períodos do ano, e sua relação com as características espermáticas em caprinos da raça Moxotó, criados no semiárido Nordestino, através da eletroforese bidimensional e espectrometria de massa. Verificou-se que a variação sazonal do clima nesta região mostrou não interferir nos parâmetros espermáticos dos caprinos, apresentando prevalência de proteínas ácidas e de baixo peso molecular em ambos os períodos. No entanto, o período seco apresentou menor diversidade de proteínas diferencialmente expressas em relação ao período chuvoso. Foram detectados dois spots protéicos, exclusivamente no período chuvoso, sugerindo pertencerem à família das GSPs. Na espectrometria de massa foram identificadas oito proteínas, sendo as de função conhecida e presentes no período seco, a histone H100-like, que protege a cromatina, e a RNA polymerase, envolvida na transcrição durante a espermatogênese. Já no período chuvoso identificou-se a immunoglobulin heavy chain, que protege os espermatozoides de efeitos danosos do ambiente. Os resultados obtidos mostram pela primeira vez o fingerprinting do plasma seminal de caprinos nativos Moxotó ao longo do ano na região Nordeste. Esta pesquisa poderá subsidiar futuros estudos de caracterização protéica do plasma seminal visando identificar biomarcadores para a raça Moxotó. Abstract: Climatic factors such as the high ambient temperatures in the semiarid Northeast, can influence the reproductive activity of the male goat. It is known that in this species, the seasonality is an important feature reproductive limiting productivity. .Among the goat breeds, the Moxotó presents a valuable genetic material once the animals are knowing as highly adapted to the tropical climate. The study of seminal plasma components represents an alternative to evaluate the reproductive performance through knowledge of factors that directly interfere with the fertilization process and may come to be regarded as biomarkers. Studies have shown that the seminal plasma proteins are involved in the regulation of various processes associated with reproductive physiology. This work aimed to identify changes in protein profiles in different periods of the year, and its relationship with sperm characteristics in Moxotó goats, by two-dimensional electrophoresis and mass spectrometry. It was found that the seasonal variation in this region showed not interfere with sperm parameters goats, showing prevalence of acidic proteins and low molecular weight in both periods. However, the dry period showed lower diversity of proteins differentially expressed in relation to rainy season. Two protein spots were detected exclusively in the rainy season, suggesting they belong to the GSP family. In mass spectrometry have been identified eight proteins, from which two of them, the histone-like H100 and the RNA polymerase are present in the dry season and protects the chromatin and it is involved in the transcription during the spermatogenesis, respectively. The other one, the immunoglobulin heavy chain, present in the rainy season, protects the spermatozoids to deleterious environment. This results showed for the first time the fingerprinting of Moxotó goat seminal plasma throughout the year in the Northeast. This research can facilitate future studies of seminal plasma protein characterization in order to identify biomarkers for Moxotó.Dissertação (Mestrado em Zootecnia) - Universidade Estadual Vale do Acaraú, Sobral. Orientadora: Ângela Maria Xavier Eloy (Embrapa Caprinos e Ovinos); Co-orientador: Raymundo Rizaldo Pinheiro (Embrapa Caprinos e Ovinos)