Coefficient of friction and subjective assessment of slippery work surfaces.

Research was conducted to determine how well subjects could distinguish between surfaces with different coefficient of friction (COF) values and to evaluate how well subjective ratings of slipperiness correlated with the actual COF values. Thirty-three ironworkers experienced in working and walking on steel surfaces and 23 university students inexperienced with these tasks participated in the study. Subjective slipperiness ratings for a variety of climbing and walking conditions were obtained from the subjects. It was found that subjects could identify differences in the slipperiness of four types of steel coatings tested in the study. There was a high correlation between the subjective ratings and the measured COF values. Subjects did not slip at a COF of 0.41 but did lose footing at a COF of 0.20.     

Childhood cancer incidence and trends in Minnesota, 1988-1994

Childhood cancer incidence patterns for Minnesota, obtained from the Minnesota Cancer Surveillance System, were compared with national rates as well as with historic data from eight Minnesota counties. In total, 1,140 neoplasms were diagnosed in children (ages 0 to 14) between 1988 and 1994. Leukemias were the most common diagnosis for boys (30.3%) and girls (29.6%), followed by central nervous system tumors. The average annual age-adjusted incidence rates for all cancer sites were 167.2 and 136.2 per million for boys and girls, respectively. These rates were somewhat higher than national rates. In particular, the incidence rate for astrocytoma in boys was significantly elevated. Childhood cancer incidence, particularly brain tumors, has increased in the eight-county region from 1969 to 1994. This analysis demonstrated the Minnesota's childhood cancer incidence patterns are similar to national patterns.     

Scheduling parallel jobs to minimize the makespan

We consider the NP-hard problem of scheduling parallel jobs with release dates on identical parallel machines to minimize the makespan. A parallel job requires simultaneously a prespecified, job-dependent number of machines when being processed. We prove that the makespan of any nonpreemptive list-schedule is within a factor of 2 of the optimal preemptive makespan. This gives the best-known approximation algorithms for both the preemptive and the nonpreemptive variant of the problem. We also show that no list-scheduling algorithm can achieve a better performance guarantee than 2 for the nonpreemptive problem, no matter which priority list is chosen. List-scheduling also works in the online setting where jobs arrive over time and the length of a job becomes known only when it completes; it therefore yields a deterministic online algorithm with competitive ratio 2 as well. In addition, we consider a different online model in which jobs arrive one by one and need to be scheduled before the next job becomes known. We show that no list-scheduling algorithm has a constant competitive ratio. Still, we present the first online algorithm for scheduling parallel jobs with a constant competitive ratio in this context. We also prove a new information-theoretic lower bound of 2.25 for the competitive ratio of any deterministic online algorithm for this model. Moreover, we show that 6/5 is a lower bound for the competitive ratio of any deterministic online algorithm of the preemptive version of the model jobs arriving over time.     

A P1-based physical map of the region from D17S776 to D17S78 containing the breast cancer susceptibility gene BRCA1

BRCA1, a breast and ovarian cancer susceptibility locus, has been isolated and maps to 17q21. A physical map of the BRCA1 region which extended from the proximal boundary at D17S776 to the distal boundary at D17S78 was constructed and consists of 51 sequence tagged sites (STSs) from P1 and YAC ends, nine new short-tandem repeat (STR) polymorphic markers, and eight identified genes. The contig, which spans the estimated 2.3 Mb region, contains 29 P1s, 11 YACs, two BACs, and one cosmid. Based on key recombinants in two linked families, BRCA1 was further localized to a region bounded by D17S1321 on the proximal side and D17S1325 on the distal side. Within this estimated 600 kb region, the contig was composed completely of P1s and BACs ordered by STS-content mapping and confirmed by DNA restriction fragment fingerprinting.     

Occupational posture exposure among construction electricians

The aim of this study is to record, objectively describe and compare working postures of Brazilian and Norwegian construction electricians. Postures of the upper arms, head, and neck during work and breaks were quantified by means of inclinometry for a representative sample of 12 Brazilian and 12 Norwegian electricians in the construction industry during a full work-shift. Despite that differences were found between specific work-related factors, Brazilian and Norwegian workers revealed a high and very similar level and pattern of postures for all evaluated body regions, suggesting that results could be extrapolated to other electricians. Upper arm elevation was high and similar for both groups and head flexion and extension was pronounced compared to other occupations. Thus, extreme postures were identified for construction electricians in both countries, with similar exposure pattern also for defined tasks (planning, support and wiredraw), suggesting that this job is risky regardless organizational differences.     

Detection of Pinosylvins in Solid Wood of Scots Pine Using Fourier Transform Raman and Infrared Spectroscopy

Abstract

Diffuse reflectance Fourier transform infrared (DRIFT) and near infrared (NIR) FT-Raman spectroscopy were used to detect pinosylvins in the wood of Pinus sylvestris L. trees. NIR FT-Raman spectroscopy offered the possibility of revealing pinosylvins simply by visual inspection of Raman spectra whereas DRIFT spectra needed a more complicated evaluation. Pinosylvin and resin acids from Scots pine were examined as to the possibility of their being the cause of observed spectral differences between sapwood and heartwood. Since pinosylvins are important compounds for the decay resistance of Scots pine wood, the detection of pinosylvins with Raman spectroscopy might be used to assess durability of wood products.     

UVB Radiation Variably Affects n-3 Fatty Acids but Elevated Temperature Reduces n-3 Fatty Acids in Juvenile Atlantic Salmon (Salmo salar)

Temperature and ultraviolet B radiation (UVB 290–320?nm) are inextricably linked to global climate change. These two variables may act separately, additively, or synergistically on specific aspects of fish biochemistry. We raised Atlantic Salmon (Salmo salar) parr for 54?days in outdoor tanks held at 12 and 19?°C and, at each temperature, we exposed them to three spectral treatments differing in UV radiation intensity. We quantified individual fatty acid (FA) mass fractions in four tissues (dorsal muscle, dorsal and ventral skin, and ocular tissue) at each temperature?×?UV combination. FA composition of dorsal muscle and dorsal and ventral skin was not affected by UV exposure. Mass fractions of 16:0, 18:0, and saturated fatty acids (SFA) were greater in dorsal muscle of warm-reared fish whereas 18:3n-3, 20:2, 20:4n-6, 22:5n-3, 22:6n-3, n-3, n-6, polyunsaturated fatty acids (PUFA), and total FA were significantly higher in cold-reared fish. Mass fractions of most of the FA were greater in the dorsal and ventral skin of warm-reared fish. Cold-reared salmon exposed to enhanced UVB had higher ocular tissue mass fractions of 20:2, 20:4n-6, 22:6n-3, n-3, n-6, and PUFA compared to fish in which UV had been removed. These observations forecast a host of ensuing physiological and ecological responses of juvenile Atlantic Salmon to increasing temperatures and UVB levels in native streams and rivers where they mature before smolting and returning to the sea.