A Raman scattering-based method to probe the carrier drift velocity in semiconductors: Application to gallium nitride

A single expression relating the carrier drift velocity in semiconductors under an electric field to Raman scattering data is derived resorting to a full nonequilibrium picture for electrons and holes. It allows one to probe with high optical precision both the ultrafast transient as well as the steady state carriers' drift velocity in semiconductor systems. This is achieved by simply modifying the experimental geometry, thus changing the angle between the transferred wave vector Q and the applied electric field E, and measuring the frequency shift promoted by the presence of the field to be observed in the single-particle and plasmon scattering spectra. An application to zinc-blende gallium nitride is presented to highlight the power of the method. (C) 2004 American Institute of Physics.85184055405

Direct determination of molybdenum in polyvitaminic tablets by voltammetry in non-aqueous media.

Adsorptive stripping voltammetry carried out in a homogeneous ternary solvent composed of N,N-dimethylformamide, water and ethanol, with alpha-benzoinoxime (alpha BO) as the complexing agent for Mo(VI) and a 0.5 mol L-1 acetic acid - sodium acetate buffer as supporting electrolyte was successfully used for the determination of molybdenum in polyvitamin-polymineral tablets. Tablet samples were analyzed and the results were compared with those obtained both by graphite furnace atomic absorption and by recovery tests, with good correlations. indicating that this may be considered as an alternative procedure for routine determination of Mo(VI) in pharmaceutical samples.29115315

Os efeitos do cigarro e do consumo de café sobre a formação óssea e a integração óssea de implantes de hidroxiapatita

The present study aims to assess the effects of cigarette smoke inhalation and/or coffee consumption on bone formation and osseous integration of a dense hydroxyapatite (DHA) implant in rats. For this study, 20 male rats were divided into four groups (n = 5): CT (control) group, CE (coffee) group, CI (cigarette) group and CC (coffee + cigarette) group. During 16 weeks, animals in the CI group were exposed to cigarette smoke inhalation equivalent to 6 cigarettes per day; specimens in the CE group drank coffee as liquid diet; and rats in the CC group were submitted to both substances. In the 6th week a 5 mm slit in the parietal bone and a 4 mm slit in the tibia were performed on the left side: the former was left open while the latter received a DHA implant. As soon as surgeries were finished, the animals returned to their original protocols and after 10 weeks of exposure they were euthanised (ethically sacrificed) and the mentioned bones collected for histological processing. Data showed that exposure to cigarette smoke inhalation and coffee consumption did not interfere in weight gain and that solid and liquid diet consumption was satisfactory. Rats in the CC group showed a decrease in bone neoformation around the tibial DHA implant (31.8 ± 2.8) as well as in bone formation in the parietal slit (28.6 ± 2.2). On their own, cigarette smoke inhalation or coffee consumption also led to diminished bone neoformation around the implant and delayed the bone repair process in relation to the CT group. However, reduction in the bone repair process was accentuated with exposure to both cigarette smoke inhalation and coffee consumption in this study.O presente estudo teve como objetivo avaliar os efeitos do tabagismo e do consumo de café, isolada ou concomitantemente, sobre a formação óssea e a osseointegração de implantes hidroxiapatita densa. Foram utilizados 20 ratos machos, divididos em quatro grupos (n = 5): grupo CT (controle); grupo CA (café); grupo CI (cigarro), e grupo CC (cigarro + café). Durante 16 semanas, os animais do grupo CI foram expostos à fumaça de seis cigarros/dia; os animais do grupo CA consumiram café como dieta líquida, e os animais do grupo CC, ambas as substâncias. Após seis semanas de exposição, uma falha óssea de 5 mm foi produzida no osso parietal esquerdo e de 4 mm, na tíbia esquerda dos animais. A falha do parietal foi mantida aberta, enquanto na tíbia corpos cerâmicos de hidroxiapatita densa (HAD) foram implantados em cavidade produzida cirurgicamente. Após as cirurgias, os animais retornaram aos protocolos experimentais e, ao término de dez semanas, foram eutanasiados, sendo as tíbias e os parietais coletados para processamento histológico. A exposição à fumaça do cigarro e o consumo de café não interferiram no ganho de peso dos animais, e os consumos de dieta líquida e sólida foram satisfatórios entre os grupos. Os animais do grupo CC apresentaram menor volume de osso neoformado ao redor do implante de HAD na tíbia (31,8 ± 2,8) e menor osteogênese na falha produzida no osso parietal (28,6 ± 2,2). O café e o cigarro consumidos isoladamente provocam a diminuição do volume de osso ao redor do implante e o atraso no processo de reparação óssea. Observou-se que o consumo de café associado à exposição à fumaça do cigarro reduziu de forma acentuada o processo de reparação óssea, no presente estudo.17317

Evaluating regulatory strategies for mitigating hydrological risk in Brazil through diversification of its electricity mix

Hydroelectricity provides approximately 65% of Brazil’s power generating capacity, making the country vulnerable to droughts, which are becoming increasingly frequent. Current energy law and policy responses to the problem rely on a sectorial approach and prioritise energy security and market regulation. Brazil has opted to increase energy security levels during periods of hydrological variability with national grid interconnection and thermal plants backup. Additionally, Brazil has created the Energy Reallocation Mechanism (MRE) to manage the generators’ financial impacts in times of insufficient water. This policy, however, was unable to avoid the high financial exposure of generators in the spot market during the severe droughts experienced in the period 2013-2017. To explore how a more diversified electricity matrix can contribute to reducing hydrological risk, this article uses Integrated Assessment Modelling (IAM) techniques to analyse future macroeconomic and energy scenarios for Brazil in a global context, aligned with the Brazilian Nationally Determined Contributions (NDC) under the 2015 Paris Agreement on Climate Change. We show that the addition of non-hydro renewables is an advantage from the integrated Water-Energy-Food nexus perspective because it reduces trade-offs amongst the water and energy sectors. Our conclusions suggest that a nexus perspective can provide useful insights on how to design energy laws and policies.Philomathia Foundation; Cambridge Humanities Research Grant

The MHC Gene Region of Murine Hosts Influences the Differential Tissue Tropism of Infecting Trypanosoma cruzi Strains

We have previously demonstrated that both parasite genetic variability and host genetic background were important in determining the differential tissue distribution of the Col1.7G2 and JG T. cruzi monoclonal strains after artificial infections in mice. We observed that the JG strain was most prevalent in hearts of mouse lineages with the MHC haplotype H-2d (BALB/c and DBA2), while Col1.7G2 was predominant in hearts from C57BL/6 mice, which have the H-2b haplotype. To assess whether the MHC gene region indeed influenced tissue tropism of T. cruzi, we used the same two parasite strains to infect C57BL/6 (H-2b) and C57BLKS/J (H-2d) mice; the latter strain results from the introgression of DBA2 MHC region into the C57BL/6 background. We also performed ex vivo infections of cardiac explants from four congenic mice lineages with the H-2b and H-2d haplotypes arranged in two different genetic backgrounds: C57BLKS/J (H-2d) versus C57BL/6 (H-2b) and BALB/c (H-2d) versus BALB/B10-H2b (H-2b). In agreement with our former observations, Col1.7G2 was predominant in hearts from C57BL/6 mice (H-2b), but we observed a clear predominance of the JG strain in hearts from C57BLKS/J animals (H-2d). In the ex vivo experiments Col1.7G2 also prevailed in explants from H-2b animals while no predominance of any of the strains was observed in H-2d mice explants, regardless of the genetic background. These observations clearly demonstrate that the MHC region influences the differential tissue distribution pattern of infecting T. cruzi strains, which by its turn may be in a human infection the determinant for the clinical forms of the Chagas disease

PHLEBOTOMINE FAUNA (DIPTERA: PSYCHODIDAE) IN AN AREA OF FISHING TOURISM IN CENTRAL-WESTERN BRAZIL

The aim of this study was to identify behavioral aspects of the sandfly fauna of a fishing tourism area in the municipality of Bonito (MS). Monthly captures were undertaken from December 2009 to November 2010, using automatic CDC type light traps, from 18h00 to 06h00, in a forested area, a savannah area, peridomiciles and animal shelters near peridomiciliary areas. Nyssomyia whitmani was the most frequent out of a total of 6,699 specimens collected, belonging to 16 species, followed by Psathyromyia bigeniculata and Lutzomyia longipalpis, found in all the environments investigated, though in their greatest numbers in the animal shelters. Ny. whitmani exhibited its highest frequencies during the dry months, coincident with the fishing season, when the risk of transmission of cutaneous leishmaniasis for tourists and inhabitants increases. Noteworthy was the finding of two species naturally infected by flagellates: Ny. whitmani and Pa. bigeniculata. The local population and visiting tourists should be warned of the threat posed by leishmaniasis and the health authorities alerted to the need for adopting environmental sanitary measures, especially regarding such animal shelters as they seem to provide favorable conditions to the proliferation, maintenance and breeding opportunities of phlebotomines