Determining the Progression of Damage in Materials Subjected to Sustained Random Loads Using an Adaptive Finite Impulse Response Approach

It is often important to establish the ability of materials to withstand dynamic loads. This ability is best determined by subjecting the elements to sustained random loads under controlled conditions. It is during these fatigue endurance tests that the loss of structural integrity of a material or an element needs to be quantified. The research presented herein uses a recently developed continuous structural integrity assessment technique to evaluate variations in the mechanical properties (namely stiffness) of materials. The effectiveness of the technique was evaluated by undertaking controlled experiments, during which damage was simulated by varying the stiffness (in this case the length of a cantilever beam) of a physical single degree‐of‐freedom vibratory system subjected to random base excitation. Additional experiments where materials were allowed to naturally decay (structurally) under sustained random loads were also performed. Overall, the results presented in this study indicate that the technique can be a practical and effective tool for detecting small variations in the structural integrity of materials subjected to sustained random loads.     

Perihospitalization patterns of hemoglobin levels and erythropoiesis‐stimulating agent doses in US hemodialysis patients, 1998–2009

Anemia management in hemodialysis patients is of primary importance for clinicians and dialysis providers. Through a retrospective claims analysis, we studied prevalent US hemodialysis patients 1998–2009, and examined patterns of hemoglobin levels and erythropoiesis‐stimulating agent (ESA, epoetin [EPO], and darbepoetin [DPO] ) doses surrounding hospitalization events. Medicare outpatient claims were used to determine monthly ESA doses and associated hemoglobin levels. ESA dose trajectories were defined with repeated measures models incorporating an autoregressive covariance matrix that compared subsequent measurements with the index month of hospitalization, with variance component covariance matrices chosen for pair‐wise comparisons. Regarding prehospitalization hemoglobin levels, a biphasic pattern occurred in both the EPO (1998–2009, n = 161,242) and DPO (2004–2009, n = 4391) populations; levels rose from 1998 to 2004, fell thereafter in the EPO population, and fell after 2006 or 2007 in the DPO population. In the EPO population, the proportions of patients with hemoglobin less than 10 g/dL were 30.1% in 1998, 14.5% in 2004, and 28.3% in 2009; corresponding values for the DPO population were 21.0% in 2004 and 31.6% in 2009. While some degree of year‐to‐year variability occurred, EPO dose trends were less pronounced, with an apparent peak in 2004 followed by a modest decline; trends were similar for DPO. Trends in EPO dose trajectories did not completely parallel those for hemoglobin level; while EPO doses increased yearly up to 2004, doses stabilized, but did not materially decrease after 2004. No definite annual trends for DPO dose trajectories were apparent.     

Explaining the variation in the shear force of lamb meat using sarcomere length, the rate of rigor onset and pH

The temperature when the pH=6.0 (temp@pH6) impacts on the tenderness and eating quality of sheep meat. Due to the expense, sarcomere length is not routinely measured as a variable to explain variation in shear force, but whether measures such as temp@pH6 are as useful a parameter needs to be established. Measures of rigor onset in 261 carcases, including the temp@pH6, were evaluated in this study for their ability to explain some of the variation in shear force. The results show that for 1 day aged product combinations of the temp@pH6, the pH at 18 °C and the pH at 24 h provided a larger reduction (almost double) in total shear force variation than sarcomere length alone, with pH at 24 h being the single best measure. For 5 day aged product, pH at 18 °C was the single best measure. Inclusion of sarcomere length did represent some improvement, but the marginal increase would not be cost effective.     

State-of-the-art principles and practices of medical economics

Genomic DNA from 23 patients with isolated growth hormone (GH) deficiency (12 males and 11 females: heights -4.9 +/- 1.4 SDS) was screened for GH gene deletions by restriction endonuclease analysis of polymerase chain reaction amplification products. Three unrelated patients had typical features of severe GH deficiency and deletions (6.7 kb in two and 7.6 kb in one) of the GH gene. The two patients with 6.7-kb deletions developed growth-attenuating anti-GH antibodies whereas the patient with the 7.6-kb deletion continued to grow with GH replacement therapy. Our finding that 3/23 (approximately 13%) Brazilian subjects had GH gene deletions agrees with previous studies of severe isolated GH deficiency subjects in other populations. Two of three subjects (67%) with deletions developed blocking antibodies despite administration of exogenous GH at low doses. Interestingly, only 1/10 of cases with affected relatives or parental consanguinity had GH-1 gene deletions.     

Recovery from sevoflurane anesthesia: a comparison to isoflurane and propofol anesthesia

BACKGROUND: Sevoflurane has a lower blood:gas partition coefficient than isoflurane, which may cause a more rapid recovery from anesthesia; it also might cause faster emergence times than for propofol-based anesthesia. We evaluated a database that included recovery endpoints from controlled, randomized, prospective studies sponsored by Abbott Laboratories that compared sevoflurane to isoflurane or propofol when extubation was planned immediately after completion of elective surgery in adult patients. METHODS: Sevoflurane was compared to isoflurane in eight studies (N=2,008) and to propofol in three studies (N=436). Analysis of variance was applied using least squares method mean values to calculate the pooled mean difference in recovery endpoints between primary anesthetics. The effects of patient age and case duration also were determined. RESULTS: Sevoflurane resulted in statistically significant shorter times to emergence (-3.3 min), response to command (-3.1 min), orientation (-4.0 min) and first analgesic (-8.9 min) but not time to eligibility for discharge (-1.7 min) compared to isoflurane (mean difference). Times to recovery endpoints increased with increasing case duration with isoflurane but not with sevoflurane (patients receiving isoflurane took 4-5 min more to emerge and respond to commands and 8.6 min more to achieve orientation during cases longer than 3 hr in duration than those receiving sevoflurane). Patients older than 65 yr had longer times to orientation, but within any age group, orientation was always faster after sevoflurane. There were no differences in recovery times between sevoflurane and propofol. CONCLUSIONS: Recovery from sevoflurane was 3-4 min faster than with isoflurane in all age groups, and the difference was magnified in longer-duration surgical cases (> 3 hr).     

Sexual and nonsexual boundary violations involving psychologists, clients, supervisees, and students: Implications for professional practice.

What is available to psychologists to assist them in identifying or minimizing the damage that can result from inappropriate professional boundary crossings? Frequency data of both sexual and nonsexual boundary violations by psychologists are provided as they occurred with clients, supervisees, and students. The impact of engaging in such relationships on subsequent professional practice is also reported. Data on 18 nonsexual boundary crossings are described, and guidelines for making decisions about crossing accepted professional boundaries are provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Endothelin 1 mediates ex vivo coronary vasoconstriction caused by exogenous and endogenous cytokines

Treatment of rats with cytokines has been associated with an increase in the circulating levels of endothelin 1 (ET-1). Here we show that administration of tumor necrosis factor alpha (TNF-alpha; 4 micrograms.kg-1) to anesthetized rats caused within 15 min a strong elevation in the circulating levels of ET-1. This was associated with a striking coronary vasoconstriction in hearts from these animals when they were removed and perfused in vitro by the Langendorff technique. This vasoconstriction was largely overcome by treatment with either the endothelin type A (ETA) receptor antagonist FR 139317 or antibody against ET-1. Furthermore, it was mimicked by in vivo exposure to exogenous ET-1. Endogenously produced TNF-alpha may also cause such a coronary vasoconstriction, for treatment with interleukin 2 (600 micrograms.kg-1) produced an increase in coronary perfusion pressure that correlated with the increases in circulating TNF-alpha. This coronary vasoconstriction was substantially reversed by treatment either with antibody against TNF-alpha or with FR 139317. We suggest, therefore, that cytokine-driven changes in the production of ET-1 are key events in the development of vascular pathologies.