Fatigue crack initiation and propagation of binder-treated powder metallurgy steels

Many of the targeted applications for powder-metallurgy materials, particularly in the automotive industry, undergo cyclic loading. It is, therefore, essential to examine the fatigue mechanisms in these materials. The mechanisms of fatigue-crack initiation and propagation in ferrous powder-metallurgy components have been investigated. The fatigue mechanisms are controlled primarily by the inherent porosity present in these materials. Since most, if not all, fatigue cracks initiate and propagate at the specimen surface, surface replication was used to determine the role of surface porosity in relation to fatigue behavior. Surface replication provides detailed information on both initiation sites and on the propagation path of fatigue cracks. The effect of microstructural features such as pore size and pore shape, as well as the heterogeneous microstructure on crack deflection, was examined and is discussed. Fracture surfaces were examined to elucidate a mechanistic understanding of fatigue processes in these materials.     

Consent to treatment by minors attending accident and emergency departments: guidelines

The absolute right to refuse medical treatment, even if the reasons are irrational, is confined to competent adults. Children under 16 years can give legal consent to treatment in the absence of consent from those with parental responsibility. Children under 18 years do not, however, have an absolute right to consent, or refuse to consent, to treatment. The views of children assume increasing importance with age and maturity. Accident and emergency medical and nursing staff may face difficult decisions when children, or those with parental responsibility, refuse to consent to medical treatment. This paper presents guidelines designed to guide the decision making process in immediately or potentially life threatening conditions and in non-life-threatening conditions.     

Evaluation of humoral immune responses in cattle grazing endophyte-infected or endophyte-free fescue

Anecdotal reports suggest cattle with fescue toxicosis may not respond to vaccination and thus, experience increased incidence of Bovine Respiratory Disease Complex (BRDC) when shipped to feedlots. Fescue toxicosis causes hypoprolactemia in cattle. Hypoprolactemia decreases humoral immune responses in mice. Therefore, a study was conducted to compare the magnitude of primary and secondary humoral immune responses against specific antigens in cattle grazing endophyte-infected or endophyte-free fescue. Angus steers were blocked by weight and allocated into four groups. Two groups grazed endophyte-infected (EI) fescue and the other two groups grazed endophyte-free (EF) fescue. All steers were injected IM on d 0 and 21 with lysozyme without adjuvant and concanavalin. A (Con A) with sheep red blood cells (SRBC) in incomplete adjuvant of Freund. Steers were bled on days 0, 21 and 35 post-vaccination. Average daily gains (ADG), alkaline phosphatase (ALP) activity, cholesterol concentrations, rectal temperatures, and serum prolactin concentrations were measured to confirm fescue toxicosis in steers grazing EI fescue. Antibodies to Con A and SRBC were determined by ELISA and hemagglutination assay, respectively. The ADG were decreased for the EI group during the first month. Rectal temperature were elevated and serum prolactin concentrations were decreased in the EI group. Cholesterol and ALP concentrations also were decreased in the EI group. Primary and secondary immune responses against Con A tended to be increased and were increased against SRBC in the EI group. Antibodies against lysozyme were not induced in either group. In conclusion, cattle grazing EI fescue mounted similar humoral immune responses to vaccination, despite hypoprolactemia, as cattle grazing EF fescue. Increases in bovine respiratory disease in cattle maintained on EI fescue probably is not associated with lack of humoral immune response to vaccination protocols as a result of fescue toxicosis.     

Treating addictive patients at suicidal risk.

Presents a model for conceptualizing 4 basic types of suicidality among substance abusers (avoidance of painful consequences, the depressive experience of "crashing," the threat of personal loss, and environmental strain) and offers practical tips for treating the problem. Four general forms of intervention are discussed: pacing the crisis encounter; desensitizing the patient's sense of desperation; talking frankly about the suicidality; and attending to one's own needs as a counselor. These crisis-intervention tips are intended to aid counselors in handling suicidality as it is manifested in substance-abusing populations. Tips and guidelines for suicidal risk assessment with drug and alcohol abusers are given. (PsycINFO Database Record (c) 2010 APA, all rights reserved)