8,977 research outputs found
Determination of the scattering length for Rb-Cs X ground electronic state using a variational method
We performed the calculation of the scattering length for the elastic
collision between the rubidium and cesium atoms. For this we applied a
variational procedure based on the R-matrix theory for unbound states employing
the finite element method (FEM) for expansion of the wave-function in terms of
a finite set of local basis functions. The FEM presents as advantages the
possibility of the development of a efficient matrix inversion algorithm which
significantly reduces the computation time to calculate the R matrix. We also
tested a potential energy curve with spectroscopic accuracy obtained before
from a direct adjustment procedure of experimental data of the
state based on genetic algorithm. The quality of our result
was evaluated by comparing them with several ones previously published at
literature.Comment: 15 pages, 6 tables and 2 figure
^1S_0 pairing correlations in relativistic nuclear matter and the two-nucleon virtual state
We use the Gorkov formulation of the Dirac-Hartree-Fock-Bogoliubov
approximation to nuclear pairing to study the ^1S_0 nucleon-nucleon
correlations in nuclear matter. We find the short-range correlations of the
^1S_0 pairing fields to be almost identical to those of the two-nucleon virtual
state. We obtain mutually consistent results for the pairing fields, using
several different sets of effective interaction parameters, when we demand that
each of these sets places the virtual-state pole at its physical location.Comment: 11 pages, 9 PostScript figures, RevTex, submitted to Phys. Rev.
Thyroid lymphoma
Thyroid Lymphomas are rare tumors among thyroid neoplasms. Almost all types originate from B cells and the most frequent subtype is a diffuse large cell lymphoma. The majority arise in a background of Hashimoto's thyroiditis and patients present with a thyroid mass, rapidly enlarging and with pressure symptoms. The treatment depends on the histological subtype and stage of the disease but include radiotherapy and/or chemotherapy. The prognosis usually is favorable. The reported case presents a thyroid lymphoma. We discussed the clinic, diagnosis and treatment
Comparing the Early Research Performance of PhD Graduates in Labor Economics in Europe and the USA
This paper analyzes the early research performance of PhD graduates in labor economics, addressing the following questions: Are there major productivity differences between graduates from American and European institutions? If so, how relevant is the quality of the training received (i.e. ranking of institution and supervisor) and the research environment in the subsequent job placement institution? The population under study consists of labor economics PhD graduates who received their degree in the years 2000 to 2005 in Europe or the USA. Research productivity is evaluated alternatively as the number of publications or the quality-adjusted number of publications of an individual. When restricting the analysis to the number of publications, results suggest a higher productivity by graduates from European universities than from USA universities, but this difference vanishes when accounting for the quality of the publication. The results also indicate that graduates placed at American institutions, in particular top ones, are likely to publish more quality-adjusted articles than their European counterparts. This may be because, when hired, they already have several good acceptances or because of more focused research efforts and clearer career incentives.graduate programs, research productivity
Trends in economic research: An international perspective
Given the recent efforts in several countries to reorganize the research institutional setting to improve research productivity, our analysis addresses the following questions: To which extent has the recent awareness over international quality standards in economics around the world been reflected in research performance? How have individual countries fared? Do research quantity and quality indicators tell us the same story? We concentrate on trends taking place since the beginning of the 1990s and rely on a very comprehensive database of scientific journals, to provide a cross-country comparison of the evolution of research in economics. Our findings indicate that Europe is catching-up with the US but, in terms of influential research, the US maintains a dominant position. The main continental European countries, Germany, France, Italy and Spain, experienced some of the largest growth rates in economic scientific output. Other European countries, namely the UK, Norway, the Netherlands, Denmark, and Sweden, have shown remarkable progress in per capita output. Collaborative research seems to be a key factor explaining the relative success of some European countries, in particular when it comes to publishing in top journals, attained predominantly through international collaborations.research performance; publications; rankings; Europe; North-America; US
Desenvolvimento regional, efeito de localização e clusters agroindustriais no Brasil.
Objetiva-se, neste artigo, uma breve revisão da literatura acadêmica sobre o desenvolvimento regional e o efeito de localização, buscando-se, para tanto, identificar elementos que possam estar relacionados nas diversas modalidades de organização da produção local, bem como no processo de desenvolvimento recente da agroindústria de determinadas regiões do Brasil. Além de distinguir os conceitos de crescimento econômico e de desenvolvimento, busca-se aqui analisar as relações entre o desenvolvimento regional e o efeito de localização. As principais correntes das chamadas teorias de localização industrial, assim como as principais formas de organização da produção local, com destaque para os clusters e os distritos industriais italianos, são aqui enfocadas. Por fim são sintetizadas algumas análises especializadas sobre clusters agroindustriais no Brasil e seus efeitos sobre o desenvolvimento regional
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