A Laplace transform method for energy multigroup hybrid discrete ordinates slab lattice calculations

In typical lattice cells where a highly absorbing, small fuel element is embedded in the moderator, a large weakly absorbing medium, high-order transport methods become unnecessary. In this work we describe a hybrid discrete ordinates (SN) method for energy multigroup slab lattice calculations. This hybrid SN method combines the convenience of a low-order SN method in the moderator with a high-order SN method in the fuel. The idea is based on the fact that in weakly absorbing media whose physical size is several neutron mean free paths in extent, even the S2 method (P1 approximation), leads to an accurate result. We use special fuel-moderator interface conditions and the Laplace transform (LTSN) analytical numerical method to calculate the two-energy group neutron flux distributions and the thermal disadvantage factor. We present numerical results for a range of typical model problems

A Laplace transform method for energy multigroup hybrid discrete ordinates slab lattice calculations

In typical lattice cells where a highly absorbing, small fuel element is embedded in the moderator, a large weakly absorbing medium, high-order transport methods become unnecessary. In this work we describe a hybrid discrete ordinates (SN) method for energy multigroup slab lattice calculations. This hybrid SN method combines the convenience of a low-order SN method in the moderator with a high-order SN method in the fuel. The idea is based on the fact that in weakly absorbing media whose physical size is several neutron mean free paths in extent, even the S2 method (P1 approximation), leads to an accurate result. We use special fuel-moderator interface conditions and the Laplace transform (LTSN) analytical numerical method to calculate the two-energy group neutron flux distributions and the thermal disadvantage factor. We present numerical results for a range of typical model problems

On the violation of a local form of the Lieb-Oxford bound

In the framework of density-functional theory, several popular density functionals for exchange and correlation have been constructed to satisfy a local form of the Lieb-Oxford bound. In its original global expression, the bound represents a rigorous lower limit for the indirect Coulomb interaction energy. Here we employ exact-exchange calculations for the G2 test set to show that the local form of the bound is violated in an extensive range of both the dimensionless gradient and the average electron density. Hence, the results demonstrate the severity in the usage of the local form of the bound in functional development. On the other hand, our results suggest alternative ways to construct accurate density functionals for the exchange energy.Comment: (Submitted on 27 April 2012

Application of hyaluronic acid in non-surgical treatment of periodontitis

Poster apresentado no 2º Congresso Internacional do CiiEM: Translational Research and Innovation in Human in health Sciences. 11-13 Junho 2017, Campus Egas Moniz, Caparica, PortugalN/

Evidence of Bartonella spp., Rickettsia spp. and Anaplasma phagocytophilum in domestic, shelter and stray cat blood and fleas, Portugal.

Thirty-two fleas were collected from 18 Lisboncats, 29 of which (90.6%) were C. felis, one (3.1%)was C. canis and two (6.3%) were unidentifiable. Only C. felis fleas were infected, six (40.0%)withB. clarridgeiae and six (40.0% ) with R. felis; three(20.0%) were co-infected. No positive result wasfound for A. phagocytophilum. The infection prev-alence of B. clarridgeiae was higher in domestic(43.8%) than in shelter cat fleas (28.6%). However,the infection rate of R. felis was higher in shelter(42.9%) than in domestic cat fleas (25.0%). Straycat fleas were only infected with R. felis (11.1%).Twenty-five cats (67.7%) were bacteraemic(Table 1). Twenty-one of them (84.0%) wereless than 1 year old, 15 (60.0%) were femalea nd 10 (40.0%) had no Bartonella spp. antibodies, one of which (10.0%) was more than 1 year old. The prevalence of Bartonella bacteraemia is higher in shelter (76.9%) than in domestic cats(68.2%) and all stray cats tested (n = 2) were positive

The role of metal ions in the electron transport through azurin-based junctions

We studied the coherent electron transport through metal–protein–metal junctions based on a blue copper azurin, in which the copper ion was replaced by three different metal ions (Co, Ni and Zn). Our results show that neither the protein structure nor the transmission at the Fermi level change significantly upon metal replacement. The discrepancy with previous experimental observations suggests that the transport mechanism taking place in these types of junctions is probably not fully coherent

Thrombophilia screening: An artificial neural network approach

Thrombotic disorders have severe consequences for the patients and for the society in general, being one of the main causes of death. These facts reveal that it is extremely important to be preventive; being aware of how probable is to have that kind of syndrome. Indeed, this work will focus on the development of a decision support system that will cater for an individual risk evaluation with respect to the surge of thrombotic complaints. The Knowledge Representation and Reasoning procedures used will be based on an extension to the Logic Programming language, allowing the handling of incomplete and/or default data. The computational framework in place will be centered on Artificial Neural Networks.This work is funded by National Funds through the FCT – Fundação para a Ciência e a Tecnologia (Portuguese Foundation for Science and Technology) within projects PEst-OE/EEI/UI0752/2014 and PEst-OE/QUI/UI0619/2012

Análise e validação de metodologia para determinação de ametrina, diuron, hexazinona e tebutiuron em filé de tilápia.

Resumo: Embora os herbicidas sejam amplamente utilizados nas atividades agrícolas, o impacto desta utilização sobre a qualidade das águas é pouco conhecido e tem sido alvo de estudos em todo o mundo, sendo que efeitos mutagênicos e genotóxicos já foram observados em peixes expostos a herbicidas. Para se avaliar a toxicidade das misturas dos herbicidas tebutiuron, ametrina e do produto comercial Velpar K (diuron e hexazinone), amplamente empregados na cultura canavieira, foi necessário desenvolver e validar um método analítico capaz de detectar e quantificar a presença destes herbicidas em tilápia. A extração dos analitos foi realizada por meio do método QuECHERS (Quick, Easy, Cheap, Effective, Rugged and Safe) modificado, seguido de uma etapa de clean-up denominada extração em fase sólida dispersiva (D-SPE). As separações cromatográficas foram realizadas utilizando-se um sistema LC-MSMS, dotado de uma fonte de eletronebulização tipo electrospray, modo de ionização positivo, e analisador tipo triploquadrupolo (QqQ). As curvas analíticas obtidas para todos os compostos estudados apresentaram coeficiente de correlação linear (r2) maiores ou iguais a 0,99, limite de quantificação (LOQ) igual a 0,00125 ?g g-1 e exatidão entre 70 e 120 %