On the subsequent yielding of an aluminum alloy following cyclic prestraining

Thin-walled tubular samples of 6061 aluminum alloy are cycled in the axial direction between reversed stress limits until a steady-state condition is achieved. Following cyclic loading, the samples are subjected to internal pressure to determine the subsequent hoop tensile yield strength. A small-offset definition of yield is employed to relate the onset of plastic flow to dislocation processes. Samples in the -T651 and -0 tempers are studied, and, it is found that the subsequent yield strength determined in this way may be greater than, less than, or nearly equal to the initial hoop tensile yield strength depending on the interaction of three factors: i) the relationship between the Bauschinger effect and the cross effect under plane, biaxial stress loading, ii) the initial state of the material (i.e., degree of initial anisotropy), and iii) the final state of the material after axial cyclic loading (i.e., dislocation structure and deformation history). This work was supported by the Atomic Energy Commission.     

Property rights versus stewardship

Industries and families continue to forsake American cities for suburban and formerly rural sites, simultaneously leaving non-productive sites (“brownfields”) in the cities and removing “greenfield” land from agricultural or biologically productive use. With a few exceptions, urban regions that once functioned as communities are continuing to undergo economic and social decline. Discussion or debate about the problem (including whether it is a problem at all) invokes often-unexamined systems of values or worldviews. Students of business, manufacturing engineering, and industrial engineering are taught about the importance of site selection for new production facilities from a competitiveness perspective; but social and environmental impacts per se of these economics based decisions are not part of the criteria. The author argues that decisions regarding new site locations made by manufacturing companies also should include social and environmental values in addition to economic criteria. Because it is in the public interest for companies to incorporate these additional decision criteria, the public policy process must be used to create incentive. A method is offered to help mitigate the problem of colliding worldviews     

CL 218-872 pretreatment and intervention block kainate-induced convulsions and neuropathology.

Two experiments were conducted to test the antiepileptic properties of CL 218-872, a triazolopyridizine reported to have anxiolytic and anticonvulsant effects without accompanying sedative and ataxic effects. In Exp 1 pretreatment with CL 218-872, a recently synthesized and potent triazolopyridizine, reduced kainic acid-induced convulsions and subsequent neuropathology in rats given ip doses of 25 mg/kg or greater. CL 218-872 at doses of 50 mg/kg or greater was more effective than a high dose of diazepam (20 mg/kg) in blocking status epilepticus-like convulsions and the associated widespread neuropathological sequelae. Moreover, diazepam pretreatment was associated with a higher mortality rate than CL 218-872. In Exp 2 the efficacy of intervention with 20 mg/kg diazepam was compared with that of 50 mg/kg CL 218-872 in suppressing ongoing convulsions and reducing subsequent brain damage following a convulsant dose of kainic acid. Although CL 218-872 and diazepam were equally effective behaviorally (i.e., in suppressing kainic acid-induced convulsions), CL 218-872 was superior in its ability to reduce subsequent neuropathology, especially in the hippocampus and neocortex. Because kainic acid has been suggested as a model for human status epilepticus, CL 218-872 may be a potentially therapeutic treatment for this disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feedback to nurse managers about staff nurses'' perceptions of their jobs

Perioperative antibiotic administration can decrease surgical morbidity, shorten hospitalization, while lowering the overall costs attributable to infections. Its use in surgery is widespread and often inappropriate. In this study, the authors evaluate the guidelines for selection and use of prophylactic antibiotics in surgical cancer patients at the Hospital of Cancer in Rio de Janeiro, Brazil. During 36 non-consecutive months, 1681 cancer patients submitted to surgical procedures were prospectively followed-up by members of the Hospital Infection Control Committee. The overall surgical site infection (SSI) and mortality rates were 17.7% and 4.8% respectively. Prophylactic antibiotics were used in 1262 elective surgeries (75.1%), and their use was not considered to be in accordance with the recommended protocol in 37.6% of the cases. The inadequate antimicrobial prophylaxis resulted in higher incidence of SSI than did prophylaxis in according to the protocol (21.7% vs. 16.4, Relative Risk 1.32; 95% Confidence Internal 1.05-1.67; p0.01). This study calls the attention for the need of a more strict and determined educational program in order to provide mechanisms for an adequate administration of prophylactic antibiotics to patients submitted to high-risk surgeries.     

Mechanical properties of molybdenum-sealing glass-ceramics

Elastic constants, thermal expansion, strength, and fracture toughness were determined for a glass-ceramic which bonds to molybdenum and matches its thermal expansion. Mechanical properties of the glass-ceramic were related to microstructure following two different crystallization treatments and moderate changes in composition. Crystallization increases the toughness and modulus of the parent glass even while the residual glass properties decline. Fracture toughness of the composite is shown to depend primarily upon properties of the separate phases; however, internal stresses are shown to decrease toughness without decreasing Young's modulus.     

Cultural risks of technological innovation: the case of schoolviolence

Affluent nations have instituted various systems for heading off some of the worst consequences that new technologies can pose for the environment and for human health/safety. Action to protect against sociocultural risks from innovation is uncommon, however, despite the fact that intangible aspects of social life are crucial in determining whether humans experience their lives as meaningful and satisfying. To help raise the visibility of the social risks of technological innovation, we focus on one small piece of this large domain: the application of technology to affect human behavior. To date, most applications of surety technology in schools have been designed to enable response to an undesirable incident rather than prevention by foresight, but that may be changing. Use of many of these technologies is controversial, yet the decision-making process allows some people to make choices that affect many others without their consent. Inasmuch as humans' peaceful coexistence depends in no small part on shared cultural norms and voluntary cooperative behavior, the rush to substitute technological fixes for the difficult, time-consuming process of social negotiation is a trend which thoughtful technologists will want to ponder