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91.
92.
Quantitative estimates of dust exposure in a diatomaceous earth (DE) mining and milling operation have been derived based on air sampling records for the period 1948-1988. A total of 6395 records was included in the analysis. Conversion of results obtained by particle counting, expressed as millions of particles per cubic feet (mppcf) of gravimetrically from a filter cassette and expressed as mg m-3 total, were converted to mg m-3 respirable dust using a conversion factor derived from data obtained during the same periods at the plant. Conversion factors were calculated as the average difference of means on the log scale in order to provide stable and consistent conversions and as a ratio of arithmetic means so that the results could be compared with similar studies. After converting the available data to mg m-3 respirable dust, geometric mean (geometric standard deviation) concentrations were 0.37 (2.43) during the 1950s and 0.17 (2.35) during later periods. Exposures were estimated using two linear models, one estimating the changes in concentration over time, and the other providing job-specific mean exposures during the more recent period. Extrapolation of the estimates to periods prior to the availability of any data was done using a subjectively-determined scaling factor. The average estimated respirable dust concentrations for 135 jobs were 3.55 (+/-1.25), 1.37 (+/-0.48), 0.47 (+/-0.16) and 0.29 (+/-0.10) mg m-3 prior to 1949, 1949-1953, 1954-1973 and 1974-1988, respectively. Despite the limitations of the available data, the estimation procedures used are expected to provide reasonable quantitative estimates of silica-containing dust exposure for subsequent exposure-response analyses. 相似文献
93.
Gutierrez Peter M.; Osman Augustine; Kopper Beverly A.; Barrios Francisco X.; Bagge Courtney L. 《Canadian Metallurgical Quarterly》2000,47(4):403
A group of 211 students at a midwestern university completed the Suicidal Behaviors Questionnaire (M. M. Linehan & S. L. Nielsen, 1981), Adult Suicidal Ideation Questionnaire (W. M. Reynolds, 1991a), Multi-Attitude Suicide Tendency Scale (I. Orbach et al., 1991), Beck Helplessness Scale (A. T. Beck, A. Weissman, D. Lester, & L. Trexler, 1974), and the Reasons for Living Inventory (M. M. Linehan, L. J. Goodstein, S. L. Nielsen, & J. A. Chiles, 1983) to determine if this group of commonly used self-report measures can distinguish between individuals with high and low levels of suicidal ideation and history of self-harmful behaviors. Exploratory principal-axis factor analysis resulted in an interpretable 2-factor solution accounting for 36.2% of the variance in suicidality. Support for convergent validity of the chosen measures was also found. It appears that rapid, accurate assessment of university student suicide risk is possible. Implications for reduction of suicide risk in this segment of the population are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
94.
Jiaren Liu Zhenguo Lu Raymond S. Poole P.J. Barrios P.J. Poitras D. 《Photonics Technology Letters, IEEE》2008,20(2):81-83
A multiwavelength laser with maximum signal-to-noise ratio up to 62 dB was demonstrated on the basis of a 461-m-long InAs-InGaAsP quantum-dot waveguide Fabry-Perot cavity chip. It has 24 channels with 0.8-nm channel spacing and 8.0-dB maximum channel intensity nonuniformity over a wavelength range from 1612 to 1632 nm. Its channel spacing irregularity due to linear intracavity waveguide dispersion was also investigated. 相似文献
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96.
We conducted a study to investigate ethnic group differences in levels of serum markers used in screening for Down's syndrome [serum alpha-fetoprotein (AFP), unconjugated oestriol (uE3), total human chorionic gonadotrophin (hCG), free alpha- and free beta-hCG, and dimeric inhibin-A], to estimate the extent to which maternal weight differences between ethnic groups explain these differences, and to estimate the effect of adjusting for ethnic group and maternal weight on screening performance. Serum measurements were taken from women who were screened prenatally for Down's syndrome. AFP, uE3, and hCG concentrations were available from 9462 white, 4215 black, and 4392 South Asian women with singleton pregnancies without Down's syndrome or neural tube defects between 15 and 22 weeks' gestational age. Frozen serum samples were available from a subset of 922 white, 449 black, and 135 South Asian women and were used for measurement of free alpha-hCG, free beta-hCG, and inhibin. Values were expressed as multiples of the median (MOM) for women of the same gestational age. There were statistically significant differences in the serum marker levels between ethnic groups that were not explained by differences in maternal weight. The main differences were found in black women compared with white women; black women had serum AFP levels 22 per cent higher (95 per cent confidence interval 20-24 per cent), total hCG levels 19 per cent higher (16-22 per cent), and free beta-hCG levels 12 per cent (3-21 per cent) higher. The other differences were less than 10 per cent. Adjusting for ethnic group only had a small estimated effect on screening performance: a maximum of about 0.5 per cent extra detection at a 5 per cent false-positive rate. At a fixed risk cut-off level, the false-positive rate will not be materially different between different ethnic groups. Adjusting serum markers for ethnic groups improves Down's syndrome screening performance to a very small extent. It is worthwhile because of its established value in AFP screening for open neural tube defects. 相似文献
97.
GS Firestein F Echeverri M Yeo NJ Zvaifler DR Green 《Canadian Metallurgical Quarterly》1997,94(20):10895-10900
98.
99.
DP McHale S Mitchell S Bundey L Moynihan DA Campbell CG Woods NJ Lench RF Mueller AF Markham 《Canadian Metallurgical Quarterly》1999,64(2):526-532
Cerebral palsy has an incidence of approximately 1/500 births, although this varies between different ethnic groups. Genetic forms of the disease account for approximately 1%-2% of cases in most countries but contribute a larger proportion in populations with extensive inbreeding. We have clinically characterized consanguineous families with multiple children affected by symmetrical spastic cerebral palsy, to locate recessive genes responsible for this condition. The eight families studied were identified from databases of patients in different regions of the United Kingdom. After ascertainment and clinical assessment, we performed a genomewide search for linkage, using 290 polymorphic DNA markers. In three families, a region of homozygosity at chromosome 2q24-q25 was identified between the markers D2S124 and D2S148. The largest family gave a maximum LOD score of 3.0, by multipoint analysis (HOMOZ). The maximum combined multipoint LOD score for the three families was 5.75. The minimum region of homozygosity is approximately 5 cM between the markers D2S124 and D2S2284. We have shown that a proportion of autosomal recessive symmetrical spastic cerebral palsy maps to chromosome 2q24-25. The identification of genes involved in the etiology of cerebral palsy may lead to improved management of this clinically intractable condition. 相似文献
100.