Superconductivity in a two dimensional extended Hubbard model

The Roth's two-pole approximation has been used by the present authors to investigate the role of $d-p$ hybridization in the superconducting properties of an extended $d-p$ Hubbard model. Superconductivity with singlet $d_{x^2-y^2}$-wave pairing is treated by following Beenen and Edwards formalism. In this work, the Coulomb interaction, the temperature and the superconductivity have been considered in the calculation of some relevant correlation functions present in the Roth's band shift. The behavior of the order parameter associated with temperature, hybridization, Coulomb interaction and the Roth's band shift effects on superconductivity are studied.Comment: 14 pages, 8 figures, accepted for publication in European Physical Journal

O Sonho Transdisciplinar

O presente trabalho foi encomendado no ano de 2014, por ocasião de conferência ministrada pelo Prof.Hilton Japiassú na UFT. Após a conferência, a então gestão da Universidade Federal do Tocantins instituiu o Prêmio Hilton Japiassú de Excelência em Pesquisa, através de sua Pró-Reitoria de Pesquisa e Pós-graduação. Em homenagem ao referido professor, a comissão editorial de Desafios decidiu manter o texto original, tal como foi enviado em sua primeira versão. O Prof.Hilton Japiassu faleceu, no Rio de Janeiro, no ano de 2015

Bioenergetic analysis of human peripheral blood mononuclear cells

Leukocytes respond rapidly to pathogenic and other insults with responses ranging from cytokine production through to migration and phagocytosis. These are bioenergetically expensive and increased glycolytic flux provides ATP rapidly to support these essential functions. However, much of this work is from animal studies. To better understand the relative role of glycolysis and oxidative phosphorylation in human leukocytes, especially their utility in a translational research setting, we undertook a study of human peripheral blood mononuclear cells (MNCs) bioenergetics. Glycolysis was essential during LPS-mediated IL-1, IL-6, and TNF production as 2-deoxy-D-glucose significantly decreased output of all three cytokines. After optimising cell numbers and the concentrations of all activators and inhibitors, oxidative phosphorylation and glycolysis profiles of fresh and cryopreserved/resuscitated MNCs were determined to explore the utility of MNCs for determining the bioenergetics health profile in multiple clinical settings. While the LPS-induced cytokine response did not differ significantly between fresh and resuscitated cells from the same donors, cryopreservation/resuscitation significantly affected some measures of oxidative phosphorylation mostly, but also glycolysis. Bioenergetics analysis of human MNCs provides a quick, effective means to measure the bioenergetics health index of many individuals but cryopreserved cells are not suitable for such an analysis. The translational utility of this approach was tested by comparing MNCs of pregnant and non-pregnant women to reveal increased bioenergetics health index with pregnancy but significantly reduced basal glycolysis and glycolytic capacity. More detailed analysis of discrete leukocyte populations would be required to understand the relative roles of glycolysis and oxidative phosphorylation during inflammation and other immune responses

As máscaras da ciência

A significação aparente da ciência encontra-se nas intenções subjetivas dos próprios cientistas, cuja preocupação fundamental seria a busca do conhecimento,e nas intenções dos que elaboram a política científica, tendo em vista o aumento da produção de bens como decorrência da produção de conhecimentos.O cientista, no mundo atual, saiu da ficção neutralista e com ele a ciência. Por isso estamos diante de dois mitos da ciência: o mito da ciência-que-conduz-necessariamente-ao-progresso e o da ciência-pura-e-imaculada. Segundo o primeiro a ciência se expõe a ser julgada pelo valor social de seus resultados e de acordo com o segundo a ciência é seu próprio fim,não tendo que prestar contas a nenhuma instância exterior. Se há crise na ciência é porque os cientistas se interrogam sobre a significação e função reais, na sociedade, de seus trabalhos (H.B.) Abstract One can find the apparent meaning of science in the subjective intentions of the scientists themselves, in which the fundamental preocupation would be the search of knowledge, and in the intentions of those who are responsible for science policy, having in mind the growth of the produce of wealth as a resultof the produce of knowledge.Nowadays the neutrality was left out by the scientist and so was science. That's why we're facing the twomyths of science: the science that leads to progressand the pure and immaculate one. According to the first one science exposes itself to be judged by the social value of its results, whereas to the secondone science is not affected by any exterior instance. Whether there's a crisis in science it is because the scientists ask themselves about the real meaning and function of their works in society.(M.P.

A crise da razão e a revanche do irracional

O presente trabalho foi encomendado no ano de 2014, por ocasião de conferência ministrada pelo Prof.Hilton Japiassú na UFT. Após a conferência, a então gestão da Universidade Federal do Tocantins instituiu o Prêmio Hilton Japiassú de Excelência em Pesquisa, através de sua Pró-Reitoria de Pesquisa e Pós-graduação. Em homenagem ao referido professor, a comissão editorial de Desafios decidiu manter o texto original, tal como foi enviado em sua primeira versão. O Prof.Hilton Japiassu faleceu, no Rio de Janeiro, no ano de 2015