5,113 research outputs found
Expansion of a finite size plasma in vacuum
The expansion dynamics of a finite size plasma is examined from an analytical
perspective. Results regarding the charge distribution as well as the
electrostatic potential are presented. The acceleration of the ions and the
associated cooling of the electrons that takes place during the plasma
expansion is described. An extensive analysis of the transition between the
semi infinite and the finite size plasma behaviour is carried out. Finally, a
test of the analytical results, performed through numerical simulations, is
presented.Comment: 4 pages with 5 figure
Comparing small area techniques for estimating poverty measures: The case study of Austria and Spain
The Europe 2020 Strategy has formulated key policy objectives or so-called "headline targets" which the European Union as a whole and Member States are individually committed to achieving by 2020. One of the five headline targets is directly related to the key quality aspects of life, namely social inclusion; within these targets, the European Union Statistics on Income and Living Condition (EU-SILC) headline indicators atriskof-poverty or social exclusion and its components will be included in the budgeting of structural funds, one of the main instruments through which policy targets are attained. For this purpose, Directorate-General Regional Policy of the European Commission is aiming to use sub-national/regional level data (NUTS 2). Starting from this, the focus of the present paper is on the "regional dimension" of well-being. We propose to adopt a methodology based on the Empirical Best Linear Unbiased Predictor (EBLUP) with an extension to the spatial dimension (SEBLUP); moreover, we compare this small area technique with the cumulation method. The application is conducted on the basis of EU-SILC data from Austria and Spain. Results report that, in general, estimates computed with the cumulation method show standard errors which are smaller than those computed with EBLUP or SEBLUP. The gain of pooling SILC data over three years is, therefore, relevant, and may allow researchers to prefer this method
Black strings in (4+1)-dimensional Einstein-Yang-Mills theory
We study two classes of static uniform black string solutions in a
(4+1)-dimensional SU(2) Einstein-Yang-Mills model. These configurations possess
a regular event horizon and corresponds in a 4-dimensional picture to axially
symmetric black hole solutions in an Einstein-Yang-Mills-Higgs-U(1)-dilaton
theory. In this approach, one set of solutions possesses a nonzero magnetic
charge, while the other solutions represent black holes located in between a
monopole-antimonopole pair. A detailed analysis of the solutions' properties is
presented, the domain of existence of the black strings being determined. New
four dimensional solutions are found by boosting the five dimensional
configurations. We also present an argument for the non-existence of finite
mass hyperspherically symmetric black holes in SU(2) Einstein-Yang-Mills
theory.Comment: 19 Revtex pages, 27 eps-figures; discussion on rotating black holes
modifie
Jasmonic acid methyl ester induces xylogenesis and modulates auxin-induced xylary cell identity with NO Involvement
In Arabidopsis basal hypocotyls of dark-grown seedlings, xylary cells may form from the pericycle as an alternative to adventitious roots. Several hormones may induce xylogenesis, as Jasmonic acid (JA), as well as indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) auxins, which also affect xylary identity. Studies with the ethylene (ET)-perception mutant ein3eil1 and the ET-precursor 1-aminocyclopropane-1-carboxylic acid (ACC), also demonstrate ET involvement in IBA-induced ectopic metaxylem. Moreover, nitric oxide (NO), produced after IBA/IAA-treatments, may affect JA signalling and interact positively/negatively with ET. To date, NO-involvement in ET/JA-mediated xylogenesis has never been investigated. To study this, and unravel JA-effects on xylary identity, xylogenesis was investigated in hypocotyls of seedlings treated with JA methyl-ester (JAMe) with/without ACC, IBA, IAA. Wild-type (wt) and ein3eil1 responses to hormonal treatments were compared, and the NO signal was quantified and its role evaluated by using NO-donors/scavengers. Ectopic-protoxylem increased in the wt only after treatment with JAMe(10 ÎĽM), whereas in ein3eil1 with any JAMe concentration. NO was detected in cells leading to either xylogenesis or adventitious rooting, and increased after treatment with JAMe(10 ÎĽM) combined or not with IBA(10 ÎĽM). Xylary identity changed when JAMe was applied with each auxin. Altogether, the results show that xylogenesis is induced by JA and NO positively regulates this process. In addition, NO also negatively interacts with ET-signalling and modulates auxin-induced xylary identity
Rotating Boson Stars in 5 Dimensions
We study rotating boson stars in five spacetime dimensions. The boson fields
consist of a complex doublet scalar field. Considering boson stars rotating in
two orthogonal planes with both angular momenta of equal magnitude, a special
ansatz for the boson field and the metric allows for solutions with nontrivial
dependence on the radial coordinate only. The charge of the scalar field equals
the sum of the angular momenta. The rotating boson stars are globally regular
and asymptotically flat. For our choice of a sixtic potential the rotating
boson star solutions possess a flat spacetime limit. We study the solutions in
flat and curved spacetime.Comment: 17 pages, 6 figure
A Fuzzy Set Approach to Measuring Violence Against Women and Its Severity
We develop a scale of severity of violence against women based on fuzzy set theory. The scale can be used
to derive fuzzy indexes of violence which account for the prevalence, frequency and severity of violence.
Using the results of the survey conducted by the European Agency for Human Rights (FRA) we find strong
congruence of ranking between the proposed scale and three widely used alternatives – the Conflict Tactic
Scale, The Severity of Violence Against Women Scale and the Index of Spouse Abuse. Unlike existing
alternatives, however, the scale that we propose is based on objective information rather than subjective
assessment; it is parsimonious in terms of the amount of information that it requires; and it is less vulnerable
to risks of cultural bias. As an example of the uses to which fuzzy measurement of violence can be put, we
compute fuzzy indexes of intimate partner violence for European countries and find a clear, inverse
correlation across countries with the degree of gender equality
The geometry of manifolds and the perception of space
This essay discusses the development of key geometric ideas in the 19th
century which led to the formulation of the concept of an abstract manifold
(which was not necessarily tied to an ambient Euclidean space) by Hermann Weyl
in 1913. This notion of manifold and the geometric ideas which could be
formulated and utilized in such a setting (measuring a distance between points,
curvature and other geometric concepts) was an essential ingredient in
Einstein's gravitational theory of space-time from 1916 and has played
important roles in numerous other theories of nature ever since.Comment: arXiv admin note: substantial text overlap with arXiv:1301.064
Immunopresence and functional activity of prostaglandin-endoperoxide synthases and nitric oxide synthases in bovine corpora lutea during diestrus
The aim of this study was to evaluate the occurrence and the activity of prostaglandin-endoperoxide synthase 1 (PTGS1), PTGS2, and endothelial, neuronal, and inducible nitric oxide synthase (e-, n-, and iNOS) in early, mid, late, and regressive corpora lutea (CL) of bovines during diestrus. PTGS1 immunoreactivitywas localised mainly in the cytoplasm of small luteal cells, whereas PTGS2 was detected in the cytoplasm of large luteal cells during early, mid, and late stages. The immunoexpression of all NOS isoforms was observed in the nuclei of luteal cells in the CL stages examined. PTGS1 enzyme activity was higher in late CL and lower in regressive ones; PTGS2 increased from early to late CL andlowered in regressive ones. Constitutive NOS enzymatic activity (eNOS plus nNOS) was higher in late CL and lower in regressive ones; iNOS was lower in regressive CL. These results support the idea that PTGSs and NOSs regulate the bovine CL life span mainly during the transition from the luteotrophic to the luteolytic phase
Charged State of a Spherical Plasma in Vacuum
The stationary state of a spherically symmetric plasma configuration is
investigated in the limit of immobile ions and weak collisions. Configurations
with small radii are positively charged as a significant fraction of the
electron population evaporates during the equilibration process, leaving behind
an electron distribution function with an energy cutoff. Such charged plasma
configurations are of interest for the study of Coulomb explosions and ion
acceleration from small clusters irradiated by ultraintense laser pulses and
for the investigation of ion bunches propagation in a plasma
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