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

Caracterização de resíduos gerados em análises químicas de tecidos vegetais.

Este trabalho apresenta a caracterização dos resíduos gerados em análises químicas de tecidos vegetais do Laboratório de Análises de Solos e Plantas - LASP da Embrapa Amazônia Ocidental

Diagnóstico rápido participativo (DRP) como método de avaliação do programa de gerenciamento de resíduos laboratoriais (PGRL).

Na Embrapa, o DRP vem sendo utilizado pelo grupo de educação ambiental que adaptou o nome Diagnóstico Rural Participativo para Diagnóstico Rápido Participativo

Anatomía comparada de los fascioláridos Pustulatirus ogum y Hemipolygona beckyae de Brasil (Gastropoda: Buccinoidea: Peristerniinae)

The Brazilian species Pustulatirus ogum and Hemipolygona beckyae were examined, and certain morphological characters were described. Both species were originally assigned to the genus Latirus, considered as a heterogeneous complex. The radulae of both species are like that which characterizes Latirus, in which the innermost cusp of the rachidian tooth is well developed but always smaller than the other cusps. This feature differs from Leucozonia, in which this cusp is reduced or absent. The penis tapers terminally, and the tapered part may be long (more than half the total penis length), as in H. beckyae, or very short (less than half the total penis length), as in P. ogum. The anatomical data observed in both species are discussed under the framework of fasciolariid systematics and they appear to be widespread among other fasciolariid species. For this reason, to date, the soft-part features here provided and those known from previously studied species of Latirus are not useful for delineating precise generic diagnoses.Se describe la morfología y anatomía de las especies brasileñas Pustulatirus ogum y Hemipolygona beckyae. Ambas especies han sido tradicionalmente asignadas al género Latirus, que en la actualidad se considera que agrupa a un conjunto heterogéneo de especies. Las rádulas de ambas especies son como la que caracteriza a Latirus, con la cúspide más interna del diente raquídeo bien desarrollada y siempre menor que las otras cúspides. Esta característica difiere de la que presentan las especies del género Leucozonia, en las que esta cúspide está reducida o ausente. El pene se estrecha en su parte terminal, y la parte cónica puede ser larga (más de la mitad de la longitud total del pene), como en H. beckyae, o muy corta (menos de la mitad de la longitud total del pene), como en P. ogum. Los caracteres morfológicos observados en ambas especies se discuten en el marco de la sistemática de los Fasciolariidae y parecen estar ampliamente distribuidos en otras especies de fascioláridos. Por ello, hasta la fecha, las características de las partes blandas del animal aquí descritas y las conocidas previamente de otras especies de Latirus no se consideran de utilidad para la diagnosis de los géneros en esta familia

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

What Physical Education Teachers Know About Asthma: Impact of a Training Course

info:eu-repo/semantics/publishedVersio

Honey bee attractants and pollination in sweet orange, Citrus sinensis (L.) Osbeck, var. Pera-Rio

This experiment studied the frequency and behavior of insects on sweet orange flowers, Citrus sinensis (L.) Osbeck, their effect on fruit production (quantity and quality), nectar and pollen collection, and the effectiveness of different attractants. Over three consecutive years, the most frequent visitor to the flowers was Apis mellifera (Africanized). Flowers visited less than ten times showed low fructification. Fruit production was 35.30% greater in uncovered flowers. Fruit mean weight was much greater in uncovered (180.2g) than in covered flowers (168.5g). Fruits from the covered were more acid (1.411g of citric acid/100ml of juice) than the uncovered flowers (1.164g of citric acid/100ml of juice). The number of seeds per bud was higher in the uncovered (1 seed/bud) than in the covered treatment (0.8 seed/bud). Bee-HereR, eugenol, geraniol, citral, and lemon grass extract, mainly diluted in water, were effective in attracting honeybees to orchards. However, these compounds were less effective when diluted in sugar syrup. The same products had variable attractiveness to honeybees in different years

Resolving Kirchhoff’s laws for parallel Li-ion battery pack state-estimators

A state-space model for Li-ion battery packs with parallel-connected cells is introduced. The key feature of the model is an explicit solution to Kirchhoff’s laws for parallel-connected packs, which expresses the branch currents directly in terms of the model’s states, applied current, and cell resistances. This avoids the need to solve these equations numerically. To illustrate the potential of the proposed model for pack-level control and estimation, a method to bound the error of a state-estimator is introduced and the modeling framework is generalized to a class of electrochemical models. It is hoped that the insight brought by this model formulation will allow the wealth of results developed for series-connected packs to be applied to those with parallel connections