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Search Results: 1 - 10 of 4320 matches for " Emmanuel Schaan "
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The stability of stratified, rotating systems and the generation of vorticity in the Sun
Steven A. Balbus,Emmanuel Schaan
Physics , 2012, DOI: 10.1111/j.1365-2966.2012.21729.x
Abstract: We examine the linear behavior of three-dimensional Lagrangian displacements in a stratified, shearing background. The isentropic and iso-rotation surfaces of the equilibrium flow are assumed to be axisymmetric, but otherwise fully two-dimensional. Three-dimensional magnetic fields are included in the perturbation equations; however the equilibrium is assumed to be well-described by purely hydrodynamic forces. The model, in principle very general, is used to study the behavior of fluid displacements in an environment resembling the solar convection zone. Some very suggestive results emerge. All but high-latitude displacements align themselves with the observed surfaces of constant angular velocity. The tendency for the angular velocity to remain constant with depth in the bulk of the convective zone, together with other critical features of the rotation profile, emerge from little more than a visual inspection of the governing equation. In the absence of a background axial angular velocity gradient, displacements exhibit no poleward bias, suggesting that solar convection "plays-off" of prexisting shear rather than creates it. We argue that baroclinic vorticity of precisely the right order is generated at the radiative/convective zone boundary due to centrifugal distortion of equipotential surfaces that is not precisely followed by isothermal surfaces. If so, many features of the Sun's internal rotation become more clear, including: i) the general appearance of the tachocline; ii) the extension of differential rotation well into the radiative zone; iii) the abrupt change of morphology of convective zone isorotation surfaces; and iv) the inability of current numerical simulations to reproduce the solar rotation profile without imposed entropy boundary conditions.
Joint likelihood function of cluster counts and $n$-point correlation functions: Improving their power through including halo sample variance
Emmanuel Schaan,Masahiro Takada,David N. Spergel
Physics , 2014, DOI: 10.1103/PhysRevD.90.123523
Abstract: Naive estimates of the statistics of large scale structure and weak lensing power spectrum measurements that include only Gaussian errors exaggerate their scientific impact. Non-linear evolution and finite volume effects are both significant sources of non-Gaussian covariance that reduce the ability of power spectrum measurements to constrain cosmological parameters. Using a halo model formalism, we derive an intuitive understanding of the various contributions to the covariance and show that our analytical treatment agrees with simulations. This approach enables an approximate derivation of a joint likelihood for the cluster number counts, the weak lensing power spectrum and the bispectrum. We show that this likelihood is a good description of the ray-tracing simulation. Since all of these observables are sensitive to the same finite volume effects and contain information about the non-linear evolution, a combined analysis recovers much of the "lost" information and obviates the non-Gaussian covariance. For upcoming weak lensing surveys, we estimate that a joint analysis of power spectrum, number counts and bispectrum will produce an improvement of about $30-40\%$ in determinations of the matter density and the scalar amplitude. This improvement is equivalent to doubling the survey area.
Taking the Universe's Temperature with Spectral Distortions of the Cosmic Microwave Background
J. Colin Hill,Nick Battaglia,Jens Chluba,Simone Ferraro,Emmanuel Schaan,David N. Spergel
Physics , 2015,
Abstract: The cosmic microwave background (CMB) energy spectrum is a near-perfect blackbody. The standard model of cosmology predicts small spectral distortions to this form, but no such distortion of the sky-averaged CMB spectrum has yet been measured. We calculate the largest expected distortion, which arises from the inverse Compton scattering of CMB photons off hot, free electrons, known as the thermal Sunyaev-Zel'dovich (tSZ) effect. We show that the predicted signal is roughly one order of magnitude below the current bound from the COBE-FIRAS experiment, but can be detected at enormous significance ($\gtrsim 1000\sigma$) by the proposed Primordial Inflation Explorer (PIXIE). Although cosmic variance reduces the effective signal-to-noise to $230\sigma$, this measurement will still yield a sub-percent constraint on the total thermal energy of electrons in the observable universe. Furthermore, we show that PIXIE can detect subtle relativistic effects in the sky-averaged tSZ signal at $30\sigma$, which directly probe moments of the optical depth-weighted intracluster medium electron temperature distribution. These effects break the degeneracy between the electron density and temperature in the mean tSZ signal, allowing a direct inference of the mean baryon density at low redshift. Future spectral distortion probes will thus determine the global thermodynamic properties of ionized gas in the universe with unprecedented precision. These measurements will impose a fundamental "integral constraint" on models of galaxy formation and the injection of feedback energy over cosmic time.
Long-Term Human Induced Impacts on Marajó Island Landscapes, Amazon Estuary
Denise Schaan
Diversity , 2010, DOI: 10.3390/d2020182
Abstract: Archaeology is a discipline that can offer a long term perspective on the impacts human societies have had on the environment. Landscape studies are critical for understanding these impacts, because they embrace a dialectical view regarding the relationship between humans and their immediate surroundings. Such studies are well suited to the Amazon basin, a region that has driven much media attention due to astonishing rates of deforestation in certain areas, with likely consequences on the planet’s climate, posing challenges to the survival of the human species for the coming decades. In fact, although much has been said about the impacts of contemporary societies on tropical forest environments, ancient landscape management practices have not yet been considered part of the equation. Thus far, we know that Amerindian societies have been actively transforming their surroundings for millennia. On the eve of European contact, large, complex societies were bringing about long-lasting transformations of landscapes throughout the basin. Conquest and colonization resulted in epidemics, enslavement, and changes to the indigenous economies that managed to survive the genocide. Afterwards, as colonizers would exploit traditional resources leading, in many instances, to their exhaustion, a huge quantity of information on sustainable ways of dealing with certain environments became lost. Traditional knowledge, however, still survives among certain indigenous, peasant (caboclo), and African-Brazilian populations. Documentation of surviving management practices together with the study of the archaeological record could provide valuable information for policy makers. This article examines historical transformations that took place on Marajó Island during the last two millennia and advocates the importance of archaeological research for understanding the historical ecology of landscape change. It is argued that ancient economic strategies, some still being practiced today, could be re-created in the present, since these may constitute opportunities for sustainable sources of income to local communities.
O papel da proteína quinase C no desenvolvimento das complica??es vasculares do diabetes mellitus
Schaan, Beatriz D.;
Arquivos Brasileiros de Endocrinologia & Metabologia , 2003, DOI: 10.1590/S0004-27302003000600006
Abstract: mortality of diabetic patients is higher than that of the population at large, and results mainly from cardiovascular diseases. the putative mechanisms for the progressive atherosclerosis these patients present are direct toxic effects of glucose upon vasculature, insulin resistance, and the association of diabetes (dm) with other cardiovascular risk factors. the main determinant of the tissue damage caused by dm is hyperglycemia, which results in high intra-cellular glucose, high diacylglycerol (dag) and activation of protein kinase c (pkc). this review intends to compile the effects of hyperglycemia upon the dag-pkc pathway, vascular dysfunction related to it, and new perspectives regarding treatment of vascular chronic complications of dm based in the inhibition of this pathway.
Uma janela para a história pré-colonial da Amaz?nia: olhando além - e apesar - das fases e tradi??es
Schaan, Denise Pahl;
Boletim do Museu Paraense Emílio Goeldi. Ciências Humanas , 2007, DOI: 10.1590/S1981-81222007000100006
Abstract: in this article, it is in debate the assumed correlation between pottery industry (phase) and social group. it is argued that this assumption is not adequate to understand either variability or change in material culture. three case studies are presented in order to demonstrate that technological and iconographic similarities between artifact assemblages might correspond to different sociopolitical organizations and subsistence patterns; the identification of stylistic variability inside of a single phase might signalize political limits, as well as sociocultural identities; and typological variation (especially regarding decoration), used to define distinct phases, might mask cultural continuity and sociopolitical change within a single territory.
O papel da proteína quinase C no desenvolvimento das complica es vasculares do diabetes mellitus
Schaan Beatriz D.
Arquivos Brasileiros de Endocrinologia & Metabologia , 2003,
Abstract: A mortalidade dos pacientes com diabetes (DM) é maior do que a da popula o em geral e decorre especialmente das doen as cardiovasculares. Os prováveis mecanismos da aterosclerose acelerada nestes pacientes s o os efeitos tóxicos diretos da glicose sobre a vasculatura, a resistência à insulina e a associa o do DM a outros fatores de risco para doen a cardiovascular. O principal determinante do dano tecidual causado pelo DM é a hiperglicemia, resultando em aumento de glicose intra-celular, aumento de diacilglicerol (DAG) e ativa o da proteína quinase C (PKC). Esta revis o tem por objetivo compilar os efeitos da hiperglicemia sobre a via DAG-PKC, a disfun o vascular relacionada a ela, e, finalmente, as novas perspectivas de tratamento das complica es cr nicas vasculares do DM baseadas na inibi o desta via.
Introduction: Territorial borders and sociocultural identities: causes and meanings of the artifactual variability of archaeological records
Denise Pahl Schaan
Boletim do Museu Paraense Emílio Goeldi. Ciências Humanas , 2007,
Abstract:
A window to Amazonian precolonial history: looking beyond – and in spite of – phases and traditions
Denise Pahl Schaan
Boletim do Museu Paraense Emílio Goeldi. Ciências Humanas , 2007,
Abstract: In this article, it is in debate the assumed correlation between pottery industry (phase) and social group. It is argued that this assumption is not adequate to understand either variability or change in material culture. Three case studies are presented in order to demonstrate that technological and iconographic similarities between artifact assemblages might correspond to different sociopolitical organizations and subsistence patterns; the identification of stylistic variability inside of a single phase might signalize political limits, as well as sociocultural identities; and typological variation (especially regarding decoration), used to define distinct phases, might mask cultural continuity and sociopolitical change within a single territory.
Pierre Mendès France, French Security Politics, and the European Defense Community  [PDF]
Emmanuel Konde
Open Journal of Political Science (OJPS) , 2013, DOI: 10.4236/ojps.2013.31004
Abstract:

This paper examines the role of Pierre Mendès France in the decision of the French National Assembly to reject the European Defense Community (EDC) proposed by René Pleven in October 1950 and signed by the [Antoine] Pinay government in 1952. Since the signing of the EDC treaty in 1952, successive governments of the Fourth Republic delayed action on ratification of the treaty until 1954 when Mendès France assumed the office of prime minister and, acting against conventional wisdom, forced the National Assembly to vote on it. The EDC was a collective attempt by western European powers, with the full support of the United States, to counterbalance the overwhelming conventional military ascendancy of the Soviet Union in Europe by forming a supranational European army. This collective security plan had its origins in the French government of René Pleven in 1950. Why the French signed the treaty establishing the EDC two years later in 1952, and then rejected it in 1954 after four years of debate, is of central concern to this paper, which explores the intersection and interplay of various factors that contributed to the negative French vote.


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