Classification of journal surfaces using surface topography parameters and software methods to compensate for stylus geometry

Measurements made with a stylus surface tracer which provides a digitized representation of a surface profile are discussed. Parameters are defined to characterize the height (e.g., RMS roughness, skewness, and kurtosis) and length (e.g., autocorrelation) of the surface topography. These are applied to the characterization of crank shaft journals which were manufactured by different grinding and lopping procedures known to give significant differences in crank shaft bearing life. It was found that three parameters (RMS roughness, skewness, and kurtosis) are necessary to adequately distinguish the character of these surfaces. Every surface specimen has a set of values for these three parameters. They can be regarded as a set coordinate in a space constituted by three characteristics axes. The various journal surfaces can be classified along with the determination of a proper wavelength cutoff (0.25 mm) by using a method of separated subspace. The finite radius of the stylus used for profile tracing gives an inherent measurement error as it passes over the fine structure of the surface. A mathematical model is derived to compensate for this error

Comments on "The delamination theory of wear"

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22373/1/0000822.pd

Frictional behavior and surface failure of dental feldspathic porcelain

Wear and frictional behavior of dental feldspathic porcelain was investigated in air and in water with a single-pass sliding technique. As-glazed, gold-coated and chromium-coated porcelains were tested. Friction of the as-glazed porcelain was higher in water and surface damage was more extensive than in air. Gold-coating reduced the friction but had no apparent effect on the mode of surface failure in these environments. Chromium-coating did not reduce the friction at higher loads but did reduce the extent of surface damage when compared with the as-glazed material.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22137/1/0000566.pd

A rheological mechanism of penetrative wear

A model is proposed which explains the penetrative wear of a soft material by a harder one. Three distinct modes of penetration are present depending on the applied load. During the most severe penetration plate-like wear debris is ejected at the leading edge of the slider. A series of slip line fields is presented to approximate this debris formation process. Plastic constraint is seen to be an important factor in wear particle formation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22217/1/0000650.pd

Meta-analysis of randomized trials on the association of prophylactic acyclovir and HIV-1 viral load in individuals coinfected with herpes simplex virus-2

To summarize the randomized evidence regarding the association between acyclovir use and HIV-1 replication as measured by plasma HIV-1 RNA viral load among individuals coinfected with herpes simplex virus (HSV)-2

Association Between Unprotected Ultraviolet Radiation Exposure and Recurrence of Ocular Herpes Simplex Virus

Studies have suggested that exposure to ultraviolet (UV) light may increase risk of herpes simplex virus (HSV) recurrence. Between 1993 and 1997, the Herpetic Eye Disease Study (HEDS) randomized 703 participants with ocular HSV to receipt of acyclovir or placebo for prevention of ocular HSV recurrence. Of these, 308 HEDS participants (48% female and 85% white; median age, 49 years) were included in a nested study of exposures thought to cause recurrence and were followed for up to 15 months. We matched weekly UV index values from the National Oceanic and Atmospheric Administration to each participant's study center and used marginal structural Cox models to account for time-varying psychological stress and contact lens use and selection bias from dropout. There were 44 recurrences of ocular HSV, yielding an incidence of 4.3 events per 1,000 person-weeks. Weighted hazard ratios comparing persons with ≥8 hours of time outdoors to those with less exposure were 0.84 (95% confidence interval (CI): 0.27, 2.63) and 3.10 (95% CI: 1.14, 8.48) for weeks with a UV index of <4 and ≥4, respectively (ratio of hazard ratios = 3.68, 95% CI: 0.43, 31.4). Though results were imprecise, when the UV index was higher (i.e., ≥4), spending 8 or more hours per week outdoors was associated with increased risk of ocular HSV recurrence

HPV Genotypes in High Grade Cervical Lesions and Invasive Cervical Carcinoma as Detected by Two Commercial DNA Assays, North Carolina, 2001–2006

HPV typing using formalin fixed paraffin embedded (FFPE) cervical tissue is used to evaluate HPV vaccine impact, but DNA yield and quality in FFPE specimens can negatively affect test results. This study aimed to evaluate 2 commercial assays for HPV detection and typing using FFPE cervical specimens.Four large North Carolina pathology laboratories provided FFPE specimens from 299 women ages18 and older diagnosed with cervical disease from 2001 to 2006. For each woman, one diagnostic block was selected and unstained serial sections were prepared for DNA typing. Extracts from samples with residual lesion were used to detect and type HPV using parallel and serial testing algorithms with the Linear Array and LiPA HPV genotyping assays.LA and LiPA concordance was 0.61 for detecting any high-risk (HR) and 0.20 for detecting any low-risk (LR) types, with significant differences in marginal proportions for HPV16, 51, 52, and any HR types. Discordant results were most often LiPA-positive, LA-negative. The parallel algorithm yielded the highest prevalence of any HPV type (95.7%). HR type prevalence was similar using parallel (93.1%) and serial (92.1%) approaches. HPV16, 33, and 52 prevalence was slightly lower using the serial algorithm, but the median number of HR types per woman (1) did not differ by algorithm. Using the serial algorithm, HPV DNA was detected in >85% of invasive and >95% of pre-invasive lesions. The most common type was HPV16, followed by 52, 18, 31, 33, and 35; HPV16/18 was detected in 56.5% of specimens. Multiple HPV types were more common in lower grade lesions.We developed an efficient algorithm for testing and reporting results of two commercial assays for HPV detection and typing in FFPE specimens, and describe HPV type distribution in pre-invasive and invasive cervical lesions in a state-based sample prior to HPV vaccine introduction

Impact of Health Insurance, ADAP, and Income on HIV Viral Suppression Among US Women in the Womenʼs Interagency HIV Study, 2006–2009

Implementation of the Affordable Care Act motivates assessment of health insurance and supplementary programs, such as the AIDS Drug Assistance Program (ADAP) on health outcomes of HIV-infected people in the United States. We assessed the effects of health insurance, ADAP, and income on HIV viral load suppression

Health Insurance Type and Control of Hypertension Among US Women Living With and Without HIV Infection in the Women’s Interagency HIV Study

BACKGROUND: Health care access is an important determinant of health. We assessed the effect of health insurance status and type on blood pressure control among US women living with (WLWH) and without HIV. METHODS: We used longitudinal cohort data from the Women's Interagency HIV Study (WIHS). WIHS participants were included at their first study visit since 2001 with incident uncontrolled blood pressure (BP) (i.e., BP ≥140/90 and at which BP at the prior visit was controlled (i.e., <135/85). We assessed time to regained BP control using inverse Kaplan-Meier curves and Cox proportional hazard models. Confounding and selection bias were accounted for using inverse probability-of-exposure-and-censoring weights. RESULTS: Most of the 1,130 WLWH and 422 HIV-uninfected WIHS participants who had an elevated systolic or diastolic measurement were insured via Medicaid, were African-American, and had a yearly income ≤$12,000. Among participants living with HIV, comparing the uninsured to those with Medicaid yielded an 18-month BP control risk difference of 0.16 (95% CI: 0.10, 0.23). This translates into a number-needed-to-treat (or insure) of 6; to reduce the caseload of WLWH with uncontrolled BP by one case, five individuals without insurance would need to be insured via Medicaid. Blood pressure control was similar among WLWH with private insurance and Medicaid. There were no differences observed by health insurance status on 18-month risk of BP control among the HIV-uninfected participants. CONCLUSIONS: These results underscore the importance of health insurance for hypertension control-especially for people living with HIV