Rolling-Contact Fatigue and Wear of CVD-SiC with Residual Surface Compression

The rolling-contact fatigue life and wear of CVD-SiC coatings with surface compression were studied using a three- ball-on-rod rolling-contact fatigue (RCF) tester. Two levels of surface compression in the coatings, approximately 190 μm thick, were introduced by using substrates of a liquid-phase sintered SiC and a SiC-30 vol% TiC to obtain desired thermal-expansion mismatches with the CVD-SiC. Residual surface compressions of 250 and 680 MPa were measured in the CVD-SiC coatings on SiC and SiC-30 vol% TiC substrates, respectively, by a strain-gage technique. In the RCF test, the fatigue life of the CVD-SiC coating with the moderate surface compression was limited by severe wear by a brittle fracture mechanism at a Hertzian contact stress of 5.5 GPa. The CVD-SiC coating on the SiC-30 vol% TiC composite, on the other hand, did not show measurable wear. A majority of the tests (11 out of 16) were suspended at 100 h or stopped due to failure of the steel balls. Five tests stopped due to spalling of the CVD-SiC coating at weak interfaces 10 to 15 μm below the contact surface. Examination of the microstructure of the CVD-SiC coating in cross sections revealed that the weak interfaces that led to the spalling were related to discontinuous growth of the CVD-SiC in the form of nodules or growth regions. Elimination of these defective structures is likely to enhance the tribological performance of surface-toughened CVD-SiC.     

Calorie restriction lowers body temperature in rhesus monkeys, consistent with a postulated anti-aging mechanism in rodents

Many studies of caloric restriction (CR) in rodents and lower animals indicate that this nutritional manipulation retards aging processes, as evidenced by increased longevity, reduced pathology, and maintenance of physiological function in a more youthful state. The anti-aging effects of CR are believed to relate, at least in part, to changes in energy metabolism. We are attempting to determine whether similar effects occur in response to CR in nonhuman primates. Core (rectal) body temperature decreased progressively with age from 2 to 30 years in rhesus monkeys fed ad lib (controls) and is reduced by approximately 0.5 degrees C in age-matched monkeys subjected to 6 years of a 30% reduction in caloric intake. A short-term (1 month) 30% restriction of 2.5-year-old monkeys lowered subcutaneous body temperature by 1.0 degrees C. Indirect calorimetry showed that 24-hr energy expenditure was reduced by approximately 24% during short-term CR. The temporal association between reduced body temperature and energy expenditure suggests that reductions in body temperature relate to the induction of an energy conservation mechanism during CR. These reductions in body temperature and energy expenditure are consistent with findings in rodent studies in which aging rate was retarded by CR, now strengthening the possibility that CR may exert beneficial effects in primates analogous to those observed in rodents.     

Use caution with serologic testing for Helicobacter pylori infection in children

Commercial serologic assays accurately detect adult Helicobacter pylori infection. Their use in children remains controversial. An ELISA to detect H. pylori IgG in children was developed and compared with three commercial assays. ELISA standardization was done with sera from all ages and validation was done with another cohort of sera with known H. pylori status. Three commercial serologic assays were subsequently compared against this pediatric ELISA at independent sites, at which 142 pediatric serum samples from different countries were evaluated. The pediatric ELISA was 91.4% sensitive. Assay 3 demonstrated a sensitivity of 78%. Less sensitivity was observed for assay 1 (70%) and assay 2 (63%). Accuracy of commercial assays was greatly reduced when sera from developing countries and younger ages were evaluated. Results of serologic tests used to diagnose H. pylori should be interpreted with caution when evaluating children with abdominal pain. Accurate serologic assays in children may be more important for epidemiologic research than for clinical decision making.     

The Brother-Sister Questionnaire: Psychometric assessment and discrimination of well-functioning from dysfunctional relationships.

The purpose of this investigation was to document the utility of the 35-item Brother–Sister Questionnaire (BSQ), which could be used to discriminate dysfunctional from well-functioning sibling relationships. Two studies are reported. In the 1st study, 202 college students were selected by self-report on prescreening questions to represent 4 groups: (1) high sibling-conflict victims, (2) high sibling-conflict perpetrators, (3) those with reciprocal conflict, and (4) those with low levels of conflict (a comparison group). Group classification was validated by scores on the Conflict Tactics Scales. Ss' responses to the BSQ about sibling relationships were subjected to factor analysis with varimax rotation, confirming 4 reliable factors: Empathy, Boundary Maintenance, Similarity, and Coercion. In the 2nd study, 50 students who self-reported that they were abused by a sibling and 50 comparison Ss completed the BSQ. With the 4 factors as predictors, discriminant analyses correctly classified 82% of the abused group and 81% of the comparison group. Given these results, the BSQ is proposed as a self-report measure capable of characterizing 4 distinct qualities in sibling relationships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improving the reliability of eyewitness identification: Lineup construction and presentation.

The effects of system variables associated with lineup construction and presentation were examined in two experiments. In both experiments, subjects (university undergraduates) watched a videotaped reenactment of an armed robbery and later attempted to identify the robber from a lineup parade. In Experiment 1, lineup cues (e.g., voice, posture, and gait) and presentation mode (simulataneous vs. sequential) interacted (p p p     

Cell binding and internalization by filamentous phage displaying a cyclic Arg-Gly-Asp-containing peptide

Ligands that bind mammalian cell surface integrins with high affinity can mediate cellular internalization. We show that particles of the bacteriophage fd that display the cyclic integrin-binding peptide sequence GGCRGDMFGC in a proportion of their major coat protein subunits bind to cells and are efficiently internalized. In the displayed peptide the conformation of the RGD motif is restricted within a hairpin loop formed by a disulfide bridge between the 2 cysteine residues. Cellular internalization of phage was demonstrated by confocal and non-confocal immunofluorescence microscopy of tissue-cultured cells incubated with phage particles. The phage were contained in juxtanuclear vesicles in the same serial sections as transferrin receptor but were not colocalized with the cell surface marker alkaline phosphatase. Cell binding and internalization was inhibited by preincubation of cells with the integrin-binding peptide GRGDSP, whereas the control peptide GRGESP had no inhibitory effect. These results indicate that cyclic integrin-binding peptides can be used to target and enter cells and that it should be possible to exploit such peptides for the introduction of DNA, drugs, or other macromolecules.     

The effect of fish oil on blood pressure and high-density lipoprotein-cholesterol levels in phase I of the Trials of Hypertension Prevention. Trials of Hypertension Prevention Collaborative Research Group

OBJECTIVE: To study the effects of moderate doses of fish oil on blood pressure and high-density lipoprotein (HDL)-cholesterol. METHODS: The participants were 350 normotensive men and women aged 30-54 years who were enrolled from seven academic medical centers in phase I of the Trials of Hypertension Prevention. They were randomly assigned to receive placebo or 6 g purified fish oil once a day, which supplied 3 g n-3 polyunsaturated fatty acids for 6 months. RESULTS: Baseline blood pressure was (mean +/- SD) 123 +/- 9/81 +/- 5 mmHg. The mean differences in the blood pressure changes between the fish oil and placebo groups were not statistically significant. There was no tendency for fish oil to reduce blood pressure more in subjects with baseline blood pressures in the upper versus the lower quartile (132/87 versus 114/75 mmHg), low habitual fish consumption (0.4 versus 2.9 times a week) or low baseline plasma levels of n-3 fatty acids. Fish oil increased HDL2-cholesterol significantly compared with the placebo group. Subgroup analysis showed this effect to be significant in the women but not in the men. Increases in serum phospholipid n-3 fatty acids were significantly correlated with increases in HDL2-cholesterol and decreases in systolic blood pressure. CONCLUSION: Moderate amounts of fish oil (6 g/day) are unlikely to lower blood pressure in normotensive persons, but may increase HDL2-cholesterol, particularly in women.     

Adherence to management of high blood pressure: recommendations of the Canadian Coalition for High Blood Pressure Prevention and Control

Adherence or compliance, in the context of medical treatment, refers to how well a patient follows and sticks to the management plan developed with her/his health care provider, which may include pharmacologic agents as well as changes in lifestyle. Adherence is of great concern in asymptomatic conditions such as hypertension, where lack of control may have serious ramifications including end organ damage and premature mortality. To address this issue, the Canadian Coalition for High Blood Pressure Prevention and Control established a national Advisory Committee on Adherence to the Management of High Blood Pressure. The Advisory Committee consisted of 11 members from different disciplines of health care providers. The Committee reviewed all evidences to date and drew up four practical recommendations with respect to patient, provider and environment. Based on Canadian Task Force on Periodic Health Examination's guidelines, all four recommendations can be classified as 'level C' with a quality of evidence of II.     

Morning vs evening light treatment of patients with winter depression

BACKGROUND: According to the phase-shift hypothesis for winter depression, morning light (which causes a circadian phase advance) should be more antidepressant than evening light (which causes a delay). Although no studies have shown evening light to be more antidepressant than morning light, investigations have shown either no difference or morning light to be superior. The present study assesses these light-exposure schedules in both crossover and parallel-group comparisons. METHODS: Fifty-one patients and 49 matched controls were studied for 6 weeks. After a prebaseline assessment and a light/dark and sleep/wake adaptation baseline week, subjects were exposed to bright light at either 6 to 8 AM or 7 to 9 PM for 2 weeks. After a week of withdrawal from light treatment, they were crossed over to the other light schedule. Dim-light melatonin onsets were obtained 7 times during the study to assess circadian phase position. RESULTS: Morning light phase-advanced the dim-light melatonin onset and was more antidepressant than evening light, which phase-delayed it. These findings were statistically significant for both crossover and parallel-group comparisons. Dim-light melatonin onsets were generally delayed in the patients compared with the controls. CONCLUSIONS: These results should help establish the importance of circadian (morning or evening) time of light exposure in the treatment of winter depression. We recommend that bright-light exposure be scheduled immediately on awakening in the treatment of most patients with seasonal affective disorder.