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## Os modelos VAR e VEC espaciais : uma abordagem bayesiana

Hauer, Mariana
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
37.24%
O objetivo deste trabalho é apresentar o Modelo Vetorial Autorregressivo (VAR) e uma das suas variações, o Modelo Vetorial de Correções de Erros (VEC), segundo uma abordagem Bayesiana, considerando componentes regionais, que serão inseridos nos modelos apresentados através de informações a priori que levam em consideração a localização dos dados. Para formar tais informações a priori são utilizados conceitos referentes à econometria espacial, como por exemplo, as relações de contigüidade e as implicações que estas trazem. Como exemplo ilustrativo, o modelo em questão será aplicado a um conjunto de dados regionais, coletados por estados brasileiros. Este conjunto de dados consiste em observações da variável produção industrial para oito estados, no período de janeiro de 1991 a setembro de 2006. Em função da escolha do modelo adequado, a questão central foi descobrir em que medida a incorporação destas informações a priori no modelo VEC Bayesiano é coerente quando estimamos modelos que consideram informações localizacionais.; The main goal of this work is to present the Vector Autoregressive Model (VAR) and one of its variations, the Vector Error Correction Model (VEC), according to a Bayesian variant...

## Análise econométrica da taxa de lucro dos Estados Unidos entre 1963 e 2008 : aplicações de modelos VEC

Clemente, Leonel Toshio
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
27.24%
O objetivo geral desta dissertação é compreender como as variações da Taxa de Lucro dos EUA foram determinadas entre 1963 e 2008. Por isso faz-se necessário identificar as variáveis que afetam a Taxa de Lucro, buscar dados de variáveis proxy e especificar e estimar modelos econométricos. Por constatar-se causalidade mútua entre a Taxa de Lucro e as variáveis que a afetam, optou-se por estimar modelos VEC, os quais permitiram analisar os coeficientes de curto e longo prazo, o tempo necessário para ajuste completo das variáveis e as funções impulso-resposta para compreender as relações da Taxa de Lucro com as variáveis que a afetam. Os resultados do modelo VEC são novos em relação a Basu (2010), Shaikh (1991, 2010), Cockshott, Cottrell e Taraddinov (2009), e Duménil e Lévy (1993, 2002).; The overall objective of this dissertation is to understand the determinants of variations in the U.S. economy Rate of Profit between 1963 and 2008. Therefore, it is necessary to identify the variables that affect the rate of profit, select appropriate proxies, and specify and estimate suitable econometric models. Due to mutual causality between the profit rate and the variables that affect it, VEC models were estimated. This allowed analyzing the short and long term coefficients...

## Net Capital Flows, Macroeconomic Shocks and Reserve Assets. The Case of Argentina (1994-2013); Flujos netos de capital, choques macroecon??micos y activos de reservas. El caso argentino (1994-2013)

Lanteri, Luis N.
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; article; Art??culo Formato: application/pdf
SPA
Relevância na Pesquisa
27.07%
International reserves have been used as a source of protection against the vulnerability of the balance of payments, or alternatively, as an attempt to keep a competitive real exchange rate and to promote exports. This paper explores the correlation between the net capital flows and reserves. Similarly, the impact of some macroeconomic shocks on that variable is assessed. Estimates are carried out through both, the VEC (Vector Error Correction) models and quarterly data of the Argentine economy for the period 1994-2013. Results show a negative correlation between international reserves and net capital flows (reserve accumulation through current account surpluses). At the same time, the expansionary fiscal policies and the continuing and widespread price increases would adversely affect the reserves.; Las reservas internacionales han sido empleadas como una fuente de protecci??n contra la vulnerabilidad de la balanza de pagos, o alternativamente, para intentar mantener un tipo de cambio real competitivo y promover las exportaciones. En este trabajo se analiza la correlaci??n existente entre los flujos netos de capital y las reservas y se eval??a el efecto de algunos choques macroecon??micos en dicha variable. Las estimaciones se realizan con modelos de VEC (modelo de correcci??n de errores) y datos trimestrales de la econom??a argentina...

## Proton polarizations in polarized 3He studied with the \vec{3He} (\vec{e},e' p)d and \vec{3He} (\vec{e},e' p)pn processes

Golak, J.; Skibinski, R.; Witala, H.; Gloeckle, W.; Nogga, A.; Kamada, H.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.45%
We study within the Faddeev framework the \vec{3He} (\vec{e},e' p)d as well as the \vec{3He} (\vec{e},e' p)pn and \vec{3He} (\vec{e},e' n)pp reactions in order to extract information on the proton and neutron polarization in polarized 3He. We achieve clear analytical insight for simplified dynamical assumptions and define conditions for experimental access to important 3He properties. In addition we point to the possibility to measure the electromagnetic proton form factors in the process \vec{3He} (\vec{e},e' p)d which would test the dynamical picture and put limits on medium corrections of the form factors.; Comment: 38 pages, 22 figures

## A Model for the 3He(\vec d, p)4He Reaction at Intermediate Energies

Kamada, H.; Gloeckle, W.; Witala, H.; Gojuki, S.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.17%
Polarization correlation coefficients have been measured atRIKEN for the \vec 3He(\vec d,p)4He reaction at intermediate energies. We propose a model for the (\vec d, p) reaction mechanism using the pd elastic scattering amplitude which is rigorously determined by a Faddeev calculation and using modern NN forces. Our theoretical predictions for deuteron polarization observables A_y, A_{yy}, A_{xx} and A_{xz} at E_d=140, 200 and 270 MeV agree qualitatively in shape with the experimental data for the reaction 3He(\vec d,p)4He.; Comment: 6 pages, 11 figures, 1 table, reference: http://www.phys.ntu.edu.tw/english/fb16/contribution/topic4/Uesaka_Tomohiro1. ps in Contribution for the XVIth IUPAP International Conference on Few-Body Problems in Physics, (Taipei, Taiwan 6-11, March 2000)

## Recent STAR results and prospects of $W^{-(+)}$ boson production in polarized $\vec{p}+\vec{p}$ collisions at RHIC

Joseph Seele for the STAR Collaboration
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.24%
In 2009, the RHIC spin physics program completed the first data taking period of polarized $\vec{p}+\vec{p}$ collisions at $\sqrt{s} = 500$ GeV, accumulating ~12 pb$^{-1}$ with ~39% beam polarization. This opens a new era in the study of the spin-flavor structure of the proton based on the production of $W^{-(+)}$ bosons. $W^{-(+)}$ bosons are produced in $\bar{u}+d (\bar{d}+u)$ collisions and can be detected through their leptonic decays, $e^-+\bar{\nu_e}(e^++\nu_e)$, where only the respective charged lepton is measured. The discrimination of $\bar{u}+d$ and $\bar{d}+u$ quark combinations requires distinguishing the charge sign of high $p_T$ electrons and positrons, which in turn requires precise tracking information. At mid-rapidity, STAR relies on the Time Projection Chamber. At forward rapidity, new tracking capabilities will be provided by the Forward GEM Tracker, consisting of six triple-GEM detectors which are under construction. The suppression of QCD background over W boson signal events by several orders of magnitude is accomplished by using the highly segmented STAR Electromagnetic Calorimeters to impose isolation criteria suppressing jet events, and vetoing dijet events based on the measured away side energy. The status of the STAR results on the first measurements of the cross section and single spin asymmetry for $W^{-(+)}$ boson production in polarized $\vec{p}+\vec{p}$ collisions will be presented along with a discussion of prospects involving the STAR Forward GEM Tracker.; Comment: 5 pages...

## Determination of the strange form factors of the nucleon from $\nu p$, $\bar{\nu} p$, and parity-violating $\vec{e}p$ elastic scattering

Pate, Stephen F.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.17%
A new method of obtaining the strange form factors of the nucleon is presented, in which forward-angle parity-violating $\vec{e}p$ elastic scattering data is combined with $\nu p$ and $\bar{\nu} p$ elastic scattering data. The axial form factor in electron-nucleon scattering is complicated by the presence of electro-weak radiative corrections that in principle need to be calculated or separately measured, but this axial form factor is suppressed at forward angles. The neutrino data has no such complication. Hence the use of forward-angle parity-violating $\vec{e}p$ data with $\nu p$ and $\bar{\nu} p$ data allows the extraction of all three strange form factors: electric, magnetic and axial ($G_E^s$, $G_M^s$, and $G_A^s$). In this letter, $\nu p$ and $\bar{\nu} p$ data from the Brookhaven E734 experiment are combined with the Jefferson Lab HAPPEX $\vec{e}p$ data to obtain two distinct solutions for the strange form factors at $Q^2$ = 0.5 GeV$^2$. More generally, combining the neutrino elastic scattering data from E734 with the existing and upcoming $\vec{e}p$ data will yield the strange form factors of the nucleon for $Q^2$ of 0.45-1.05 GeV$^2$. Measurement of $G_A^s$ is crucial to the determination of the strange quark contribution to the nucleon spin...

## Measurement of double polarized asymmetries in quasi-elastic processes ${}^3\vec{He}(\vec{e},e' d)$ and ${}^3\vec{He}(\vec{e},e' p)$

Mihovilovic, Miha
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.34%
This thesis is dedicated to a study of a spin-isospin structure of the polarized ${}^3\mathrm{He}$. First, an introduction to the spin structure of ${}^3\mathrm{He}$ is given, followed by a brief overview of past experiments. The main focus of the thesis is the E05-102 experiment at Jefferson Lab, in which the reactions ${}^3\vec{\mathrm{He}}(\vec{\mathrm{e}},\mathrm{e'} \mathrm{d})$ and ${}^3\vec{\mathrm{He}}(\vec{\mathrm{e}},\mathrm{e'} \mathrm{p})$ in the quasi-elastic region were studied. The purpose of this experiment was to better understand the effects of the S'- and D-state contributions to the ${}^3\mathrm{He}$ ground-state wave-functions by a precise measurement of beam-target asymmetries $A_x$ and $A_z$ in the range of recoil momenta from 0 to about $300 \mathrm{MeV}/c$. The experimental equipment utilized in these measurements is described, with special attention devoted to the calibration of the hadron spectrometer, BigBite. Results on the measured asymmetries are presented, together with first attempts at their comparison to the state-of-the art Faddeev calculations. The remaining open problems and challenges for future work are also discussed.; Comment: Doctoral thesis, 234 pages

## Testing the correctness of the Poynting vector \vec E\times\vec B as the momentum density of gauge fields

Chen, Xiang-Song; Chen, Xiang-Bai; Sun, Wei-Min; Wang, Fan
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.43%
Following our recent finding that the renowned formula $\vec x\times (\vec E\times\vec B)$ is not the correct density for the electromagnetic angular momentum, here we examine the validity of the Poynting vector $\vec E \times\vec B$ as the electromagnetic momentum density (or energy flux). The competitor is the gauge-invariant canonical momentum $E^i\vec \nabla A^i_\perp$. It often gives the same result as $\vec E\times\vec B$, but we propose that a delicate measurement (of the {\em azimuthal} energy flow in polarized atomic radiations) can make a discrimination. By clarifying the profound difference between two kinds of energy-momentum tensors: the canonical (or mechanical) one and the symmetric (or gravitational) one, we predict that it is $E^i\vec \nabla A^i_\perp$ that would pass the delicate experimental test. Our observations have far-reaching implications for understanding the source of gravity, and the nucleon momentum as well.; Comment: 3 pages, no figure

## Polarization Observables in (${\vec e},e'{\vec N}N$) and (${\vec \gamma},{\vec N}N$) Reactions

Giusti, C.; Pacati, F. D.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.34%
Nucleon recoil polarization in electromagnetic reactions with two-nucleon emission is discussed for both (${\vec e},e'{\vec N}N$) and (${\vec \gamma},{\vec N}N$). Numerical results are given for exclusive two-nucleon knockout reactions from $^{16}$O in a theoretical model where final-state interactions, one-body and two-body currents, and the effect of correlations in the initial pair wave function are included.; Comment: 10 pages, 5 figures, Proceedings 5th Workshop on "e.-m. induced two-hadron emission", Lund, June 13-16, 2001

## Azimuthal correlation between the $(\vec{p}_l,\vec{p}_{X_b})$ and $(\vec{p}_l,\vec{P}_t)$ planes in the semileptonic rest frame decay of a polarized top quark: An $O(\alpha_s)$ effect

Groote, S.; Huo, W. S.; Kadeer, A.; Korner, J. G.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.34%
The azimuthal correlation between the planes formed by the vectors $(\vec{p}_\ell,\vec{p}_{X_b})$ and $(\vec{p}_\ell,\vec{P}_t)$ in the semileptonic rest frame decay of a polarized top quark $t(\uparrow) \to X_b + l^+ + \nu_\ell$ belongs to a class of polarization observables involving the top quark which vanish at the Born term level in the standard model. We determine the next--to--leading order QCD corrections to the afore-mentioned azimuthal correlation and compare the result to the corresponding contribution of a non--standard--model right--chiral quark current.; Comment: latex, 12 pages with 2 figures in the text, typos removed,comment and references added, replaced with published version

## Polarization transfer in 4He(\vec{e},e'\vec{p}) and 16O(\vec{e},e'\vec{p}) in a relativistic Glauber model

Lava, P.; Ryckebusch, J.; Van Overmeire, B.; Strauch, S.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.34%
Polarization-transfer components for 4He(\vec{e},e'\vec{p})3H and 16O(\vec{e},e'\vec{p})15N are computed within the relativistic multiple-scattering Glauber approximation (RMSGA). The RMSGA framework adopts relativistic single-particle wave functions and electron-nucleon couplings. The predictions closely match those of a relativistic plane-wave model indicating the smallness of the final-state interactions for polarization-transfer components. Also short-range correlations play a modest role for the studied observables, as long as small proton missing-momenta are probed in quasi-elastic kinematics. The predictions with free and various parameterizations for the medium-modified electromagnetic form factors are compared to the world data.; Comment: 24 pages, 11 figures

## The NN final-state interaction in the helicity structure of $\vec d(\vec\gamma,\pi^-)pp$ reaction

Darwish, Eed M.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.24%
The influence of final-state $NN$-rescattering on the helicity structure of the $\vec\gamma\vec d\to\pi^-pp$ reaction in the energy range from $\pi$-threshold up to 550 MeV has been investigated. The differential polarized cross-section difference for the parallel and antiparallel helicity states is predicted and compared with recent experimental data. It is shown that the effect of $NN$-rescattering is much less important in the polarized differential cross-section difference than in the previously studied unpolarized differential cross section. Furthermore, the contribution of $\vec\gamma\vec d\to\pi^-pp$ to the spin asymmetry of the deuteron is explicitly evaluated over the region of the $\Delta$(1232)-resonance with inclusion of $NN$-rescattering. The effect of $NN$ final-state interaction is found to be much larger in the asymmetry than in the total cross section and leads to an appreciable reduction of the spin asymmetry in the $\Delta$-region.; Comment: 15 pages including 4 figures, accepted for publication in Nuclear Physics A

## Beam-Recoil Polarization Transfer in the Nucleon Resonance Region in the Exclusive $\vec{e}p \to e'K^+\vec{\Lambda}$ and $\vec{e}p \to e'K^+\vec{\Sigma}^0$ Reactions at CLAS

Carman, D. S.; Raue, B. A.; Collaboration, for the CLAS
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.3%
Beam-recoil transferred polarizations for the exclusive $\vec{e}p \to e'K^+ \vec{\Lambda},\vec{\Sigma}^0$ reactions have been measured using the CLAS spectrometer at Jefferson Laboratory. New measurements have been completed at beam energies of 4.261 and 5.754 GeV that span a range of momentum transfer $Q^2$ from 0.7 to 5.4 GeV$^2$, invariant energy $W$ from 1.6 to 2.6 GeV, and the full center-of-mass angular range of the $K^+$ meson. These new data add to the existing CLAS $K^+\Lambda$ measurements at 2.567 GeV, and provide the first-ever data for the $K^+\Sigma^0$ channel in electroproduction. Comparisons of the data with several theoretical models are used to study the sensitivity to s-channel resonance contributions and the underlying reaction mechanism. Interpretations within two semi-classical partonic models are made to probe the underlying reaction mechanism and the $s\bar{s}$ quark-pair creation dynamics.; Comment: 48 pages, 22 figures

## Spin correlations in $\vec{p}\vec{p}\to pn\pi^{+}$ pion production near threshold

Daehnick, W. W.; Saha, Swapan K.; Flammang, R. W.; Meyer, H. O.; Balewski, J. T.; Pollock, R. E.; von Przewoski, B.; Rinckel, T.; Thörngren-Engblom, P.; Wellinghausen, A.; Lorentz, B.; Rathmann, F.; Schwartz, B.; Wise, T.; Pancella, P. V.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.34%
A first measurement of longitudinal as well as transverse spin correlation coefficients for the reaction $\vec{p}\vec{p}\to pn\pi^+$ was made using a polarized proton target and a polarized proton beam. We report kinematically complete measurements for this reaction at 325, 350, 375 and 400 MeV beam energy. The spin correlation coefficients $A_{xx}+A_{yy}, A_{xx}-A_{yy}, A_{zz}, A_{xz},$ and the analyzing power $A_{y},$ as well as angular distributions for $\sigma(\theta_{\pi})$ and the polarization observables $A_{ij}(\theta_{\pi})$ were extracted. Partial wave cross sections for dominant transition channels were obtained from a partial wave analysis that included the transitions with final state angular momenta of $l\leq 1$. The measurements of the ${\vec{p}\vec{p}\to pn\pi^{+}}$ polarization observables are compared with the predictions from the J\"ulich meson exchange model. The agreement is very good at 325 MeV, but it deteriorates increasingly for the higher energies. At all energies agreement with the model is better than for the reaction ${\vec{p}\vec{p}\to pp\pi^{0}}$.; Comment: Preprint, 21 pp, submitted to Phys. Rev. C. Keywords: Mesons, Polarization, Spin Correlations, Few body systems

## Stellar dynamos with $\vec{\Omega}\times \vec{J}$ effect

Pipin, V. V.; Seehafer, N.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.17%
We study axisymmetric mean-field dynamo models containing differential rotation, the $\alpha$ effect and the additional turbulent induction effects. The additional effects result from the combined action of rotation and an inhomogeneity of the large-scale magnetic field. The best known of them is the $\vec{\Omega}\times\vec{J}$ effect. We also include anisotropic diffusion and a new dynamo term which is of third order in the rotation vector $\vec{\Omega}$ The model calculations are carried out using the rotation profile of the Sun as obtained from helioseismic measurements and radial profiles of other quantities according to a standard model of the solar interior. In addition, we consider a dynamo model for a full sphere which is solely based on the joint induction effects of rotation and an inhomogeneity of the large-scale magnetic field, without differential rotation and the $\alpha$ effect (a $\delta^{2}$ dynamo model). This kind of dynamo model may be relevant for fully convective stars.; Comment: A&A, accepted

## Testing nuclear forces by polarization transfer coefficients in d(\vec p, \vec p)d and d(\vec p,\vec d)p reactions at E^{lab}_p = 22.7 MeV

Witala, H.; Golak, J.; Skibinski, R.; Glockle, W.; Nogga, A.; Epelbaum, E.; Kamada, H.; Kievsky, A.; Viviani, M.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.34%
The proton to proton polarization transfer coefficients K_x^{x'}, K_y^{y'}, K_z^{x'} and the proton to deuteron polarization transfer coefficients K_x^{x'}, K_y^{y'}, K_z^{x'}, K_x^{y'z'}, K_y^{z'z'}, K_z^{y'z'}, K_y^{x'z'} and K_y^{x'x'-y'y'} have been measured in d(\vec p, \vec p)d and d(\vec p, \vec d)p reactions at E^{lab}_p = 22.7 MeV, respectively. The data have been compared to predictions of modern nuclear forces obtained by solving the three-nucleon Faddeev equations in momentum space. Realistic (semi) phenomenological nucleon-nucleon potentials combined with model three-nucleon forces and modern chiral nuclear forces have been used. The AV18, CD Bonn, Nijm I and II nucleon-nucleon interactions have been applied alone or combined with the Tucson-Melbourne 99 three-nucleon force, adjusted separately for each potential to reproduce the triton binding energy. For the AV18 potential also the Urbana IX three-nucleon force have been used. In addition chiral NN potentials in the next-to-leading-order and chiral two- and three-nucleon forces in the next-to-next-to-leading-order have been applied. Only when three-nucleon forces are included a satisfactory description of all data results. For the chiral approach the restriction to the forces in the next-to-leading order is insufficient. Only when going over to the next-to-next-to-leading order one gets a satisfactory description of the data...

## Nuclear medium modifications of the NN interaction via quasielastic ($\vec p,\vec p '$) and ($\vec{p},\vec{n}$) scattering

Hillhouse, G. C.; van der Ventel, B. I. S; Wyngaardt, S. M.; de Kock, P. R.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.34%
Within the relativistic PWIA, spin observables have been recalculated for quasielastic ($\vec p,\vec p '$) and ($\vec p,\vec n$) reactions on a $^{40}$Ca target. The incident proton energy ranges from 135 to 300 MeV while the transferred momentum is kept fixed at 1.97 fm^{-1}. In the present calculations, new Horowitz-Love--Franey relativistic NN amplitudes have been generated in order to yield improved and more quantitative spin observable values than before. The sensitivities of the various spin observables to the NN interaction parameters, such as (1) the presence of the surrounding nuclear medium, (2) a pseudoscalar versus a pseudovector interaction term, and (3) exchange effects, point to spin observables which should preferably be measured at certain laboratory proton energies, in order to test current nuclear models. This study also shows that nuclear medium effects become more important at lower proton energies ($\leq$ 200 MeV). A comparison to the limited available data indicates that the relativistic parametrization of the NN scattering amplitudes in terms of only the five Fermi invariants (the SVPAT form) is questionable.; Comment: 10 pages, 6 Postscript figures, uses psfig.sty and article.sty, submitted to Phys. Rev. C

## Probing Deformed Orbitals with \vec{A}(\vec{e}, e' N)B reactions

Garrido, E.; Caballero, J. A.; de Guerra, E. Moya; Sarriguren, P.; Udias, J. M.
Tipo: Artigo de Revista Científica