Incident Ischemic Heart Disease After Long-Term Occupational Exposure to Fine Particulate Matter: Accounting for 2 Forms of Survivor Bias.

Little is known about the heart disease risks associated with occupational, rather than traffic-related, exposure to particulate matter with aerodynamic diameter of 2.5 µm or less (PM2.5). We examined long-term exposure to PM2.5 in cohorts of aluminum smelters and fabrication workers in the United States who were followed for incident ischemic heart disease from 1998 to 2012, and we addressed 2 forms of survivor bias. Left truncation bias was addressed by restricting analyses to the subcohort hired after the start of follow up. Healthy worker survivor bias, which is characterized by time-varying confounding that is affected by prior exposure, was documented only in the smelters and required the use of marginal structural Cox models. When comparing always-exposed participants above the 10th percentile of annual exposure with those below, the hazard ratios were 1.67 (95% confidence interval (CI): 1.11, 2.52) and 3.95 (95% CI: 0.87, 18.00) in the full and restricted subcohorts of smelter workers, respectively. In the fabrication stratum, hazard ratios based on conditional Cox models were 0.98 (95% CI: 0.94, 1.02) and 1.17 (95% CI: 1.00, 1.37) per 1 mg/m(3)-year in the full and restricted subcohorts, respectively. Long-term exposure to occupational PM2.5 was associated with a higher risk of ischemic heart disease among aluminum manufacturing workers, particularly in smelters, after adjustment for survivor bias

Ischemic Heart Disease Incidence in Relation to Fine versus Total Particulate Matter Exposure in a U.S. Aluminum Industry Cohort.

Ischemic heart disease (IHD) has been linked to exposures to airborne particles with an aerodynamic diameter <2.5 μm (PM2.5) in the ambient environment and in occupational settings. Routine industrial exposure monitoring, however, has traditionally focused on total particulate matter (TPM). To assess potential benefits of PM2.5 monitoring, we compared the exposure-response relationships between both PM2.5 and TPM and incidence of IHD in a cohort of active aluminum industry workers. To account for the presence of time varying confounding by health status we applied marginal structural Cox models in a cohort followed with medical claims data for IHD incidence from 1998 to 2012. Analyses were stratified by work process into smelters (n = 6,579) and fabrication (n = 7,432). Binary exposure was defined by the 10th-percentile cut-off from the respective TPM and PM2.5 exposure distributions for each work process. Hazard Ratios (HR) comparing always exposed above the exposure cut-off to always exposed below the cut-off were higher for PM2.5, with HRs of 1.70 (95% confidence interval (CI): 1.11-2.60) and 1.48 (95% CI: 1.02-2.13) in smelters and fabrication, respectively. For TPM, the HRs were 1.25 (95% CI: 0.89-1.77) and 1.25 (95% CI: 0.88-1.77) for smelters and fabrication respectively. Although TPM and PM2.5 were highly correlated in this work environment, results indicate that, consistent with biologic plausibility, PM2.5 is a stronger predictor of IHD risk than TPM. Cardiovascular risk management in the aluminum industry, and other similar work environments, could be better guided by exposure surveillance programs monitoring PM2.5

Particle Size Distribution in Aluminum Manufacturing Facilities.

As part of exposure assessment for an ongoing epidemiologic study of heart disease and fine particle exposures in aluminum industry, area particle samples were collected in production facilities to assess instrument reliability and particle size distribution at different process areas. Personal modular impactors (PMI) and Minimicro-orifice uniform deposition impactors (MiniMOUDI) were used. The coefficient of variation (CV) of co-located samples was used to evaluate the reproducibility of the samplers. PM2.5 measured by PMI was compared to PM2.5 calculated from MiniMOUDI data. Mass median aerodynamic diameter (MMAD) and concentrations of sub-micrometer (PM1.0) and quasi-ultrafine (PM0.56) particles were evaluated to characterize particle size distribution. Most of CVs were less than 30%. The slope of the linear regression of PMI_PM2.5 versus MiniMOUDI_PM2.5 was 1.03 mg/m3 per mg/m3 (± 0.05), with correlation coefficient of 0.97 (± 0.01). Particle size distribution varied substantively in smelters, whereas it was less variable in fabrication units with significantly smaller MMADs (arithmetic mean of MMADs: 2.59 μm in smelters vs. 1.31 μm in fabrication units, p = 0.001). Although the total particle concentration was more than two times higher in the smelters than in the fabrication units, the fraction of PM10 which was PM1.0 or PM0.56 was significantly lower in the smelters than in the fabrication units (p < 0.001). Consequently, the concentrations of sub-micrometer and quasi-ultrafine particles were similar in these two types of facilities. It would appear, studies evaluating ultrafine particle exposure in aluminum industry should focus on not only the smelters, but also the fabrication facilities

Automatic detection of equiaxed dendrites using computer vision neural networks

Equaixed dendrites are frequently encountered in solidification. They typically form in large numbers, which makes their detection, localization, and tracking practically impossible for a human eye. In this paper, we show how recent progress in the field of machine learning can be leveraged to tackle this problem and we present computer vision neural network to automatically detect equiaxed dendrites. Our network is trained using phase-field simulation results, and proper data augmentation allows to perform the detection task in solidification conditions entirely different from those simulated for training. For example, here we show how they can successfully detect dendrites of various sizes in a microgravity solidification experiment. We discuss challenges in training such a network along with our solutions for them, and compare the performance of neural network with traditional methods of shapes detection

MSSM Higgs Couplings to Bottom Quarks: Two-Loop Corrections

We present the two-loop SUSY-QCD corrections to the effective bottom Yukawa couplings within the minimal supersymmetric extension of the Standard Model. The effective Yukawa couplings include the resummation of the non-decoupling corrections Delta m_b for large values of tg(beta). We have derived the two-loop SUSY-QCD corrections to the leading SUSY-QCD and top-induced SUSY-electroweak contributions to Delta m_b. The scale dependence of the resummed Yukawa couplings is reduced from O(10%) to the per-cent level. These results reduce the theoretical uncertainties of the MSSM Higgs branching ratios to the accuracy which can be achieved at a future linear e+e- collider.Comment: 5 pages, 4 figure

Экспериментальное исследование динамики фрикционных процессов при трении латуни Л63 с ультрамелкозернистой структурой

В работе рассматривается экспериментальное исследование динамики фрикционных процессов при трении объемных ультрамелкозернистых материалов. В качестве модельных образцов использовалась латунь Л63 с крупнокристаллической и ультрамелкозернистой структурой, сформированной методом равноканального углового прессования. В процессе сухого трения скольжения осуществлялась регистрация сигналов виброускорений и акустической эмиссии. Анализ коротких сигналов с применением преобразований Фурье позволил установить характерные параметры сигналов, полученных при трении крупнокристаллических и ультрамелкозернистых материалов

Анализ термодинамических параметров нефтепровода с предварительным подогревом нефти в условиях Севера

Объектом исследования является трубопровод, на котором применяется технология перекачки нефти с предварительным подогревом. Цель работы – определить влияние термодинамических характеристик трубопроводного транспорта нефти в условиях Севера на эффективность технологии перекачки нефти с предварительным подогревом. В процессе исследования проводились гидравлические и тепловые расчеты, расчет оптимальной температуры транспорта, расчет экономической эффективности использования технологии транспорта с подогревом. Рассмотрены вопросы корректного описания вязкостно-температурной характеристики нефти для определения оптимальной температуры подогрева нефти, влияния термодинамических параметров системы «нефтепровод-окружающая среда» на эффективность применения предварительного подогрева.The object of research is the hot oil pipeline. Purpose - to determine the influence of the thermodynamic characteristics of the pipeline transport of oil in the North on the effectiveness of technology of hot oil transfer. The study carried out hydraulic and thermal calculations, the calculation of optimal transport temperature, calculation of economic efficiency of use of hot oil transport. The questions of the correct description of viscosity-temperature characteristics of the oil to determine the optimum temperature of heating oil, the effect of thermodynamic parameters of the system "pipeline-environment" on the effectiveness of transport. Presents measures for health and safety point of operation of oil heating, environmental protection, technical and economic part

Sequential loss of myelin proteins during Wallerian degeneration in the human spinal cord

Axons undergo Wallerian degeneration (WD) distal to a point of injury. In the lesioned PNS, WD may be followed by successful axonal regeneration and functional recovery. However, in the lesioned mammalian CNS, there is no significant axonal regeneration. Myelin-associated proteins (MAPs) have been shown to play significant roles in preventing axonal regeneration in the CNS. Since relatively little is known about such events in human CNS pathologies, we performed an immunohistochemical investigation on the temporal changes of four MAPs during WD in post-mortem spinal cords of 22 patients who died 2 days to 30 years after either cerebral infarction or traumatic spinal cord injury. In contrast to experimental studies in rats, the loss of myelin sheaths is greatly delayed in humans and continues slowly over a number of years. However, in agreement with animal data, a sequential loss of myelin proteins was found which was dependent on their location within the myelin sheath. Myelin proteins situated on the peri-axonal membrane were the first to be lost, the time course correlating with the loss of axonal markers. Proteins located within compact myelin or on the outer myelin membrane were still detectable 3 years after injury in degenerating fibre tracts, long after the disappearance of the corresponding axons. The persistence of axon growth-inhibitory proteins such as NOGO-A in degenerating nerve fibre tracts may contribute to the maintenance of an environment that is hostile to axon regeneration, long after the initial injury. The present data highlight the importance of correlating the well documented, lesion-induced changes that take place in controlled laboratory investigations with those that take place in the clinical domai

Regulation of stearoyl-CoA desaturase-1 after central and peripheral nerve lesions

BACKGROUND: Interruption of mature axons activates a cascade of events in neuronal cell bodies which leads to various outcomes from functional regeneration in the PNS to the failure of any significant regeneration in the CNS. One factor which seems to play an important role in the molecular programs after axotomy is the stearoyl Coenzyme A-desaturase-1 (SCD-1). This enzyme is needed for the conversion of stearate into oleate. Beside its role in membrane synthesis, oleate could act as a neurotrophic factor, involved in signal transduction pathways via activation of protein kinases C. RESULTS: In situ hybridization and immunohistochemistry demonstrated a strong up-regulation of SCD at mRNA and protein level in regenerating neurons of the rat facial nucleus whereas non-regenerating Clarke's and Red nucleus neurons did not show an induction of this gene. CONCLUSION: This differential expression points to a functionally significant role for the SCD-1 in the process of regeneration