Experimental Realization of the Fuse Model of Crack Formation

In this work, we present an experimental investigation of the fuse model. Our main goal was to study the influence of the disorder on the fracture process. The experimental apparatus used consisted of an $L\times L$ square lattice with fuses placed on each bond of the lattice. Two types of materials were used as fuses: copper and steel wool wires. The lattice composed only by copper wires varied from a weakly disordered system to a strongly disordered one. The lattice formed only by steel wool wires corresponded to a strongly disordered one. The experimental procedure consisted of applying a potential difference V to the lattice and measuring the respective current I. The characteristic function $I(V)$ obtained was investigated in order to find the scaling law dependence of the voltage and the current on the system size $L$ when the disorder was changed. Our results show that the scaling laws are only verified for the disordered regime.Comment: 4 pages, 8 figures.ep

Microscopic mechanism for mechanical polishing of diamond (110) surfaces

Mechanically induced degradation of diamond, as occurs during polishing, is studied using total--energy pseudopotential calculations. The strong asymmetry in the rate of polishing between different directions on the diamond (110) surface is explained in terms of an atomistic mechanism for nano--groove formation. The post--polishing surface morphology and the nature of the polishing residue predicted by this mechanism are consistent with experimental evidence.Comment: 4 pages, 5 figure

Controle biológico aplicado e natural da lagarta-do-cartucho do milho.

bitstream/item/44201/1/controle-biologico-lagarta.pd

REVITALIZAÇÕES URBANAS EM ESPAÇOS PÚBLICOS: TEMPOS E FUNÇÕES DISTINTAS NO PORTO VELHO CIDADE DA CIDADE DO RIO GRANDE/RS.

Processos de “revitalização urbana” são frequentes em diversas cidades do mundo devido a espaços não utilizados herdados de diferentes tempos com diferentes atribuições de usos. Dessa forma estudos e políticas públicas voltadas ao tema se fazem significativas e imprescindíveis na contemporaneidade. Devido ao fato de, a maioria das cidades possuírem áreas ociosas e em muitos casos degradadas (vazios urbanos) justifica a necessidade de projetos voltados à revitalização. No entanto são diversos os casos de revitalização em solo urbano. Dentre os casos de revitalização, o presente trabalho se detém sobre uma área portuária, o Porto velho da cidade do Rio Grande/RS. O Porto se localiza junto ao centro histórico da cidade e é dotado de belezas naturais atribuídas aos corpos hídricos que o circundam. O antigo Porto detém uma infraestrutura que perpassa por praticamente dois séculos desde a fundação da cidade, assim como representa o berço da estrutura urbana encontrada nos dias atuais. Nesse ponto de vista podemos dizer que foi a partir do Porto Velho que a cidade se desenvolveu tanto em estrutura física quanto econômica, política e cultural

Differences in the Prevalence of Non-Communicable Disease between Slum Dwellers and the General Population in a Large Urban Area in Brazil.

Residents of urban slums are at greater risk for disease than their non-slum dwelling urban counterparts. We sought to contrast the prevalences of selected non-communicable diseases (NCDs) between Brazilian adults living in a slum and the general population of the same city, by comparing the age and sex-standardized prevalences of selected NCDs from a 2010 survey in Pau da Lima, Salvador Brazil, with a 2010 national population-based telephone survey. NCD prevalences in both populations were similar for hypertension (23.6% (95% CI 20.9⁻26.4) and 22.9% (21.2⁻24.6), respectively) and for dyslipidemia (22.7% (19.8⁻25.5) and 21.5% (19.7⁻23.4)). Slum residents had higher prevalences of diabetes mellitus (10.1% (7.9⁻12.3)) and of overweight/obesity (46.5% (43.1⁻49.9)), compared to 5.2% (4.2⁻6.1) and 40.6% (38.5⁻42.8) of the general population in Salvador. Fourteen percent (14.5% (12.1⁻17.0)) of slum residents smoked cigarettes compared to 8.3% (7.1⁻9.5) of the general population in Salvador. The national telephone survey underestimated the prevalence of diabetes mellitus, overweight/obesity, and smoking in the slum population, likely in part due to differential sampling inside and outside of slums. Further research and targeted policies are needed to mitigate these inequalities, which could have significant economic and social impacts on slum residents and their communities

Dermic diffusion and stratum corneum: a state of the art review of mathematical models

Transdermal biotechnologies are an ever increasing field of interest, due to the medical and pharmaceutical applications that they underlie. There are several mathematical models at use that permit a more inclusive vision of pure experimental data and even allow practical extrapolation for new dermal diffusion methodologies. However, they grasp a complex variety of theories and assumptions that allocate their use for specific situations. Models based on Fick's First Law found better use in contexts where scaled particle theory Models would be extensive in time-span but the reciprocal is also true, as context of transdermal diffusion of particular active compounds changes. This article reviews extensively the various theoretical methodologies for studying dermic diffusion in the rate limiting dermic barrier, the stratum corneum, and systematizes its characteristics, their proper context of application, advantages and limitations, as well as future perspectives

Performance of a Low Noise Front-end ASIC for Si/CdTe Detectors in Compton Gamma-ray Telescope

Compton telescopes based on semiconductor technologies are being developed to explore the gamma-ray universe in an energy band 0.1--20 MeV, which is not well covered by the present or near-future gamma-ray telescopes. The key feature of such Compton telescopes is the high energy resolution that is crucial for high angular resolution and high background rejection capability. The energy resolution around 1 keV is required to approach physical limit of the angular resolution due to Doppler broadening. We have developed a low noise front-end ASIC (Application-Specific Integrated Circuit), VA32TA, to realize this goal for the readout of Double-sided Silicon Strip Detector (DSSD) and Cadmium Telluride (CdTe) pixel detector which are essential elements of the semiconductor Compton telescope. We report on the design and test results of the VA32TA. We have reached an energy resolution of 1.3 keV (FWHM) for 60 keV and 122 keV at 0 degree C with a DSSD and 1.7 keV (FWHM) with a CdTe detector.Comment: 6 pages, 7 figures, IEEE style file, to appear in IEEE Trans. Nucl. Sc