Analysis of first ply failure in composite laminates

The mechanics of transverse cracking in an elastic fibrous composite ply is explored for the case of low crack density. Cracks are assumed to initiate from a nucleus created by localized fiber debonding and matrix cracking. It is found that cracks may propagate in two directions on planes which are parallel to the fiber axis and perpendicular to the midplane of the ply. In general, crack propagation in the direction of the fiber axis controls the strength of thin plies, while cracking in the direction perpendicular to the fiber axis determines the strength of thick plies. The theory relates ply thickness, crack geometry and ply toughness to ply strength. It predicts a significant increase in strength with decreasing ply thickness in constrained thin plies. The strength of thick plies is found to be constant, but it may be reduced by preexisting damage. Results are illustrated by comparison with experimental data.     

Criteria for judging the admissibility of eyewitness testimony of long past events.

Court cases of recovered memories of childhood abuse, in which the victim's testimony may constitute the only evidence available, and a growing body of research demonstrating the inexactitude and suggestibility of autobiographical memory of long past events, are forcing courts and cognitive scientists to seek scientific, principled criteria for admissibility of such testimony. The authors use as examples 2 recent court cases. In the 1st case, a concussion produced total retrograde amnesia for an accident for a period of 3 years, and then, over a few months, the driver claimed his memory returned. In the 2nd, 2 adults reported to the police that they witnessed their sister's murder 35 years earlier, when they were 3 and 5 years old, respectively. The authors provide objective guidelines for courts to determine whether testimony about recovered or very-long-term memory for eyewitnessed events should be admissible. The principles outlined can be expanded easily to include eyewitness testimony in general. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Blastomycosis as an etiology of acute lung injury

Blastomyces dermatitidis, a dimorphic broad-based budding yeast endemic to the Mississippi River Valley region, is responsible for morbidity in humans via inhalation and dissemination. The response of acute lung injury, which produces an illness with serious morbidity and an approximately 50% mortality, uncommonly occurs. Diagnosis can be difficult, and a high index of suspicion should be maintained in endemic regions for patients with acute lung injury of uncertain etiology, especially if their condition deteriorates on broad-spectrum antimicrobial and antitubercular therapy and they have a previous insidious respiratory complaint and constitutional symptoms. Diagnosis should be aggressively pursued and treatment with amphotericin B (0.6 to 0.8 mg/kg/day) initiated as early as possible.     

Posttraining estrogen and memory modulation

The present paper provides a review of recent research carried out in this laboratory investigating the effects of posttraining peripheral and intrahippocampal injection of estradiol on memory in rats, and estradiol-acetylcholine interactions in memory modulation. Ovariectomized rats received an eight-trial training session in a hippocampal-dependent hidden platform water maze task. Immediately following training, rats received a posttraining peripheral or intrahippocampal injection of estradiol-cyclodextrin complex or vehicle. Twenty-four hours later rats were returned to the maze for a retention test session, and latency to escape was used as a measure of memory for the previous day's training. Peripheral posttraining injection of estradiol enhances memory relative to vehicle-treated rats. Injections of estradiol given 2 h posttraining has no effect on retention, indicating a time-dependent effect of estradiol on memory storage processes. A time-dependent memory enhancing effect of posttraining intrahippocampal injections of estradiol has also been observed in both male and ovariectomized female rats. The memory enhancing effect of peripheral posttraining injection of estradiol in ovariectomized rats is blocked by a subeffective dose of the acetylcholine muscarinic receptor antagonist scopolamine, suggesting that estradiol interacts with cholinergic systems in memory modulation. Concurrent peripheral posttraining injection of a subeffective dose of estradiol and a subeffective dose of the cholinergic agonist oxotremorine produces a synergistic memory enhancing effect. The findings suggest that: (1) estradiol selectively influences memory storage independent of an effect on nonmnemonic processes, (2) the hippocampus is a potential neuroanatomical site of action mediating estrogenic effects on memory, and (3) estradiol interacts with cholinergic systems in memory modulation.     

Automatic verification of concurrent stochastic systems

Formal Methods in System Design - Automated verification techniques for stochastic games allow formal reasoning about systems that feature competitive or collaborative behaviour among rational...     

The environmental basis of sustainable development

Much economic activity depends on the environmentalresource base (soils, water, vegetation, climate) that ultimately underpins virtually all human endeavor. This environmental-resource support is obviously important for agriculture, forestry, fisheries and hydropower generation. It is less obviously important for public health: without regular supplies of domestic-household water with sufficient quantity and quality, the risk of sanitation-disease increases. Much the same applies, through indirect linkages, to such further economic sectors as communications and education.These considerations are especially significant for developing countries. A greater share of their economies is usually dependent on the environmental-resource base than is the case with developed-world economies; and at the same time, the resource base, being generally tropical in location, is more fragile and hence susceptible to depletion than is the case with temperate-zone countries. Thus there is a premium on safeguarding the environmental-resource base as an integral part of those processes known as sustainable development.This is a revised and expanded version of a paper prepared for a Seminar on Land and Water Management, Economic Development Institute, The World Bank, November 10–21, 1986. The author is a consultant in Environment and Development, Upper Meadow, Old Road, Headington, Oxford, United Kingdom. The views expressed in this paper are those of the author, and should not be attributed to the World Bank, to its affiliated organizations or to any individual acting on their behalf.     

Functional and Molecular Properties of DYT-SGCE Myoclonus-Dystonia Patient-Derived Striatal Medium Spiny Neurons

Myoclonus-dystonia (DYT-SGCE, formerly DYT11) is characterized by alcohol-sensitive, myoclonic-like appearance of fast dystonic movements. It is caused by mutations in the SGCE gene encoding ε-sarcoglycan leading to a dysfunction of this transmembrane protein, alterations in the cerebello-thalamic pathway and impaired striatal plasticity. To elucidate underlying pathogenic mechanisms, we investigated induced pluripotent stem cell (iPSC)-derived striatal medium spiny neurons (MSNs) from two myoclonus-dystonia patients carrying a heterozygous mutation in the SGCE gene (c.298T>G and c.304C>T with protein changes W100G and R102X) in comparison to two matched healthy control lines. Calcium imaging showed significantly elevated basal intracellular Ca²⁺ content and lower frequency of spontaneous Ca²⁺ signals in SGCE MSNs. Blocking of voltage-gated Ca²⁺ channels by verapamil was less efficient in suppressing KCl-induced Ca²⁺ peaks of SGCE MSNs. Ca²⁺ amplitudes upon glycine and acetylcholine applications were increased in SGCE MSNs, but not after GABA or glutamate applications. Expression of voltage-gated Ca²⁺ channels and most ionotropic receptor subunits was not altered. SGCE MSNs showed significantly reduced GABAergic synaptic density. Whole-cell patch-clamp recordings displayed elevated amplitudes of miniature postsynaptic currents and action potentials in SGCE MSNs. Our data contribute to a better understanding of the pathophysiology and the development of novel therapeutic strategies for myoclonus-dystonia.     

Impact of dietary n−3 FA deficiency on rat bone tissue FA composition

The effect of dietary n−3 FA deficiency on bone tissue FA composition was evaluated in growing rats. Two mixtures combining hydrogenated coconut oil with safflower oil served as the n−3-deficient dietary treatments and provided two levels of linoleic acid (LA). The n−3 treatments were formulated with added α-linolenic acid (LNA) from flaxseed oil (diet LNA) or LNA plus DHA, and both were balanced for LA. This study showed that bone is sensitive to changes in dietary n−3 FA and that DHA is more effective than LNA in maintaining DHA levels in these tissues.     

妊娠相关血浆蛋白A的分离及纯化

采用人胎盘血为原料,利用Sephadex G-200,DEAE-Sephadex A-50层析,Sepharose 4B反相免疫亲和层析技术,获得妊娠相关血浆蛋白A(PAPP-A)纯品,经8.0％聚丙烯酰胺凝胶电泳、免疫电泳、双向免疫扩散证明,所提取的PAPP-A纯品为单一成分。免疫家兔获得抗血清,其效价在1:16以上。     

Chlorination of polystyrene

Chlorination of a low molecular weight polystyrene in the α position was studied by following changes in the infrared spectrum, glass transition temperature, and molecular weights of the polymer. The logarithm of the absorbance ratio at 2920 and 1500 cm^?1 as a function of mole per cent chlorination was linear. The glass transition temperatures, determined by use of a differential scanning calorimeter (DSC), were found to obey an equation developed by Dyvik for copolymers. The molecular weight of the chlorinated polystyrene decreased as a function of chlorination.