Plastic Deformation of 2D Crumpled Wires

When a single long piece of elastic wire is injected trough channels into a confining two-dimensional cavity, a complex structure of hierarchical loops is formed. In the limit of maximum packing density, these structures are described by several scaling laws. In this paper it is investigated this packing process but using plastic wires which give origin to completely irreversible structures of different morphology. In particular, it is studied experimentally the plastic deformation from circular to oblate configurations of crumpled wires, obtained by the application of an axial strain. Among other things, it is shown that in spite of plasticity, irreversibility, and very large deformations, scaling is still observed.Comment: 5 pages, 6 figure

Recomendações técnicas para o processamento de conservas de cogumelos comestíveis.

Conservas de cogumelos: conservas de cogumelos esterilizados; conservas de cogumelos pasteurizados.bitstream/item/34412/1/2000-DOC-0043.pd

The reinfection threshold promotes variability in tuberculosis epidemiology and vaccine efficacy

Population patterns of infection are determined largely by susceptibility to infection. Infection and vaccination induce an immune response that, typically, reduces susceptibility to subsequent infections. With a general epidemic model, we detect a 'reinfection threshold', above which reinfection is the principal type of transmission and, consequently, infection levels are much higher and vaccination fails. The model is further developed to address human tuberculosis (TB) and the impact of vaccination. The bacille Calmette-Guérin (BCG) is the only vaccine in current use against TB, and there is no consensus about its usefulness. Estimates of protection range from 0 to 80%, and this variability is aggravated by an association between low vaccine efficacy and high prevalence of the disease. We propose an explanation based on three postulates: (i) the potential for transmission varies between populations, owing to differences in socio-economic and environmental factors; (ii) exposure to mycobacteria induces an immune response that is partially protective against reinfection; and (iii) this protection is not significantly improved by BCG vaccination. These postulates combine to reproduce the observed trends, and this is attributed to a reinfection threshold intrinsic to the transmission dynamics. Finally, we demonstrate how reinfection thresholds can be manipulated by vaccination programmes, suggesting that they have a potentially powerful role in global contro

ACTH-dependent Cushing's syndrome: a revision of 43 cases

AIM: To evaluate the characteristics and outcomes of the patients diagnosed as ACTH-dependent Cushing syndrome, registered in the department. MATERIAL AND METHODS: We reviewed the files of forty-three patients followed from 1974 to 2002. RESULTS: A progressive rise in the number of patients diagnosed was found, being 80% females. Clinical suspicion was based mostly on the typical fat distribution; hirsutism and amenorrhoea were important in women. The more reliable diagnostic tests were: 11 pm cortisol, day curve of ACTH and cortisol, and dexamethasone suppression tests. The ACTH response to CRH during inferior petrosal sinus sampling permitted the diagnosis of ectopic source. In thirty-seven patients a pituitary adenoma was diagnosed. The three patients diagnosed before 1985 went for bilateral adrenalectomy (Nelson's syndrome in two); the others were submitted to transsphenoidal pituitary adenomectomy, obtaining remission in twenty six at the first operation and in two others at the second. Three patients had a recidive. Of the six patients with persistent disease (all treated with metyrapone or ketoconazole), three were submitted to radiotherapy, two to bilateral adrenalectomy, and one was waiting for surgery. Four patients had a bronchial carcinoid, successfully removed in three. One patient was lost to follow-up and another was still being evaluated. CONCLUSIONS: We found a positive evolution in the capacity to diagnose and treat these patients. Neurosurgical ability to achieve remission was 80% in the operated cases. More effective technical methods and drugs, as well as a multidisciplinary and dedicated medical team, lead to long lasting remissions in most of the patients

Radiative Corrections to the Aharonov-Bohm Scattering

We consider the scattering of relativistic electrons from a thin magnetic flux tube and perturbatively calculate the order $\alpha$, radiative correction, to the first order Born approximation. We show also that the second order Born amplitude vanishes, and obtain a finite inclusive cross section for the one-body scattering which incorporates soft photon bremsstrahlung effects. Moreover, we determine the radiatively corrected Aharonov-Bohm potential and, in particular, verify that an induced magnetic field is generated outside of the flux tube.Comment: 14 pages, revtex, 3 figure

Comparison of methods to isolate DNA from Caesalpinia ferrea.

Molecular markers are important for characterizing the genetic diversity of plants and can provide the basis for strategies to protect and conserve endangered populations. However, numerous molecular techniques are used, requiring an evaluation of fast and efficient methods to extract DNA

Ultrasonic pulse technique for evaluation of mechanical damage in processed coffee beans.

The knowledge of the physical characteristics of the coffee bean allows the transition from the conventional storage model in bags to the silo storage, and as an indirect measure of the improvement and conservation of the quality of the stored grain. The elastic modulus allows comparisons on the strength of material. The variations of this occur due to its chemical composition, microstructures and material defects, being able to be used as indicator of the physical integrity of the grain. The ultrasonic pulse technique is an alternative to obtain the elastic modulus in a simple and non-destructive way. In this context, it was proposed the development of a non-destructive methodology that will perform the quality evaluation by determining the elastic modulus of the coffee beans. For this purpose, a reference silo was constructed, reproducing the storage conditions, and the elastic modulus values were determined. The values obtained by the Stress Wave Timer apparatus are between 2.54 and 4.23 MPa, with a maximum load of 8.32 kN, and a calculated vertical pressure of 1,526 kPa. To evaluate the impact of the storage conditions and the loads applied during the non-destructive test, laboratory tests applied in seeds were performed, and the tetrazolium test was the only one able to differentiate the samples. It was concluded that Stress Wave Timer was able to determine the elastic modulus values for the coffee bean mass and could be used as an indicative of the quality.Título em português: Técnica de pulso ultrassônico para avaliação de danos mecânicos em grãos de café beneficiados

Diversidade de fungos na madeira de cinco espécies florestais no Município de Rio Branco, Acre, Brasil.

Micologia. Resumo 211

Estudo da biodegradação de polietileno contendo aditivos pró-degradantes

A gigantesca quantidade de resíduos poliméricos produzida nas últimas décadas tem provocado a geração de poluição e danos ambientais graves, além de ser um problema para o gerenciamento de resíduos sólidos em grandes cidades. Os polímeros são materiais pouco densos e ocupam volumes consideráveis nos aterros sanitários, levando centenas de anos para se decomporem completamente em ambientes com pouca incidência de luz solar e oxigênio. A presença de materiais plásticos nos oceanos é também um problema ambiental extremamente preocupante que ameaça a existência de muitas espécies marinhas. Embora discretas, algumas iniciativas têm sido feitas tanto nos centros de pesquisa como nas indústrias para o desenvolvimento de materiais mais ambientalmente adequados. Como exemplo, tem-se as sacolas plásticas contendo aditivos pró-degradantes incorporados ao polímero, com a campanha de ser um material oxi-biodegradável. Entretanto, a biodegradação deste material tem sido motivo de grande contestação na área de pesquisa atualmente. O objetivo deste trabalho foi avaliar a biodegradação do polietileno contendo o aditivo pródegradante d2w quando submetido à presença de micro-organismos específicos, visando esclarecer muitas dúvidas a respeito da capacidade real deste material de ser degradado pela ação de micro-organismos. Amostras de polietileno contendo o aditivo d2w juntamente com amostras de polietileno sem o aditivo foram submetidas à ação de micro-organismos heterotróficos aeróbicos em condições de temperatura e umidade controladas. Em estudo prévio foi constatado que o aditivo d2w acelera a fotodegradação do polietileno. Entretanto, nenhuma afirmação pôde ainda ser feita a respeito da ação do aditivo sobre a biodegradação deste material. O desenvolvimento de materiais poliméricos de fácil fotodegradação e biodegradação é uma alternativa interessante e viável para reduzir os impactos nocivos da produção em grande escala de poliméricos sobre o meio ambiente