A power transformer as a source of noise.
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This article presents selected results of analyses and simulations carried out as part of research performed at the Central Institute of Labor Protection - the National Research Institute (CIOP-PIB) in connection with the development of a system for active reduction of noise emitted by high power electricity transformers. This analysis covers the transformer as a source of noise as well as a mathematical description of the phenomenon of radiation of vibroacoustic energy through a transformer enclosure modeled as a vibrating rectangular plate. Also described is an acoustic model of the transformer in the form of an array of loudspeakers. (+info)
Location of noise sources in fluid power machines.
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This paper discusses noise generation mechanisms and techniques for noise reduction in fluid power units. Major noise sources in fluid power units can be identified with a sound intensity method. It has been proved that components of power units with larger sound radiating surfaces such as an electric motor and an oil reservoir produce a major part of global noise radiation. (+info)
Leg lengthening with a motorized nail in adolescents : an alternative to external fixators?
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Urinary excretion of an oxidative stress marker, 8-hydroxyguanine (8-OH-Gua), among nickel-cadmium battery workers.
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The relationship between oxidative stress and carcinogenic metals including nickel and cadmium is a matter of interest. To assess the oxidative stress status of workers exposed to nickel and cadmium simultaneously, we determined urinary excretion of 8-hydroxyguanine (8-OH-Gua), a urinary oxidative stress marker. Our subjects were 66 (64 males and 2 females) nickel-cadmium battery workers. Spot urine and blood samples were collected. The levels of cadmium in blood (Cd-B) and nickel in urine (Ni-U) were determined by graphite furnace atomic absorption spectrophotometry. 8-OH-Gua in urine was analyzed using a high performance liquid chromatography-electrochemical detector (HPLC-ECD) system. Data on age, sex, duration of present work and smoking status were also obtained from each subject. Creatinine-adjusted 8-OH-Gua was significantly correlated with age, Ni-U and Cd-B in univariate analysis, while multivariate analysis revealed that Ni-U and Cd-B were significant independent variables and that these two biological exposure indices were positively correlated with 8-OH-Gua. The data were also analyzed in the context of mixture toxicity. The subjects were divided into groups based on median level of Ni-U and Cd-B (2.86 mug/g creatinine and 0.23 mug/dl, respectively). Workers with high Ni-U/high Cd-B (Group IV) had the highest levels of 8-OH-Gua levels (GM (GSD), 21.7(2.0)), followed by those with high Ni-U/low Cd-B (11.5(1.6) Group III), those with low Ni-U/high Cd-B (8.9(1.9) Group II), and those with low Ni-U/low Cd-B (8.5(1.5) Group I). The p values of Students' t-tests between Group I and Group II, III and IV were 0.847, 0.050 and <0.001, respectively. The combined effect of Cd and Ni on the urinary excretion of 8-OH-Gua departed from additivity. (+info)
Simpson's paradox visualized: the example of the rosiglitazone meta-analysis.
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How many people would benefit from a smart wheelchair?
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Independent mobility is important, but some wheelchair users find operating existing manual or powered wheelchairs difficult or impossible. Challenges to safe, independent wheelchair use can result from various overlapping physical, perceptual, or cognitive symptoms of diagnoses such as spinal cord injury, cerebrovascular accident, multiple sclerosis, amyotrophic lateral sclerosis, and cerebral palsy. Persons with different symptom combinations can benefit from different types of assistance from a smart wheelchair and different wheelchair form factors. The sizes of these user populations have been estimated based on published estimates of the number of individuals with each of several diseases who (1) also need a wheeled mobility device and (2) have specific symptoms that could interfere with mobility device use. (+info)
Hand-portable gas chromatograph-toroidal ion trap mass spectrometer (GC-TMS) for detection of hazardous compounds.
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