Effect of personal protective eyewear on postural stability

Vision is a significant factor in postural stability; this study is the first to report on the effect of OSHA regulated personal protective eyewear on physiological factors associated with postural stability. Twenty college students between the ages of 19 and 25 were randomly tested in each of three eyewear conditions (control, new, and artificially aged) using a NeuroCom Balance Master System and the mCTSIB protocol. Subjects were pre-tested with no eyewear (control) on each day followed by a 5-min assembly task with random eyewear assignment. Subjects were then post-tested following the same protocol while wearing the eyewear. Data were evaluated using a two (pre/post) x three (eyewear) repeated measures analysis of variance (ANOVA). There was a significant main effect for both the eyes open/firm flat surface, and eyes open/foam flat surface conditions (p 相似文献   

Diffusion of microspheres in sealed and open microarrays

In several experiments, we study the diffusion of microspheres with different radii in microarrays filled with a variety of aqueous solutions of ethylene glycol. We study diffusion in open and closed (sealed) microarrays. In sealed nanoliter wells, the tracers show pure diffusion, whereas in open reactors, a radial outward-directed evaporation-induced liquid flow is superimposed onto the diffusion. In general, one of the following quantities can be calculated if the others are known: the temperature, the viscosity of the medium, the radius of the microbeads, or the diffusion constant. The estimated diffusion constants in closed microarrays are in good agreement with theoretical predictions based on the Brownian motion. We monitor the motion of the microbeads under a microscope and extract their paths in time from the digital recordings. Ambiguous paths due to the crossing of two trajectories can be detected. We show that low microsphere concentrations or high viscosities do not hamper a robust estimation of the diffusion parameters.     

Effects of fiber-optic probe design and probe-to-target distance on diffuse reflectance measurements of turbid media: an experimental and computational study at 337 nm

Fiber-optic probes are widely used in optical spectroscopy of biological tissues and other turbid media. Only limited information exists, however, on the ways in which the illumination-collection geometry and the overall probe design influence the interrogation of media. We have investigated both experimentally and computationally the effect of probe-to-target distance (PTD) on the diffuse reflectance collected from an isotropically (Lambertian) scattering target and an agar-based tissue phantom. Studies were conducted with three probes characterized by either common (single-fiber) or separate (two bifurcated multifiber probes) illumination and collection channels. This study demonstrates that PTD, probe design, and tissue scattering anisotropy influence the extent of the transport of light into the medium, the light-collection efficiency, and the sampling volume of collected light. The findings can be applied toward optimization of fiber-optic probe designs for quantitative optical spectroscopy of turbid media including biological tissues.     

Juice-associated outbreaks of human illness in the United States, 1995 through 2005

Outbreaks of illness associated with consumption of fruit juice have been a growing public health problem since the early 1990s. In response to epidemiologic investigations of outbreaks in which juice was implicated, the U.S. Food and Drug Administration implemented process control measures to regulate the production of fruit juice. The final juice regulation, which became effective in 2002, 2003, and 2004, depending on the size of the business, requires that juice operations comply with a hazard analysis critical control point (HACCP) plan. The Centers for Disease Control and Prevention (CDC) receives reports of food-associated outbreaks of illness. We reviewed fruit juice-associated outbreaks of illness reported to the CDC's Foodborne Outbreak Reporting System. From 1995 through 2005, 21 juice-associated outbreaks were reported to CDC; 10 implicated apple juice or cider, 8 were linked to orange juice, and 3 involved other types of fruit juice. These outbreaks caused 1,366 illnesses, with a median of 21 cases per outbreak (range, 2 to 398 cases). Among the 13 outbreaks of known etiology, 5 were caused by Salmonella, 5 by Escherichia coli O157:H7, 2 by Cryptosporidium, and one by Shiga toxin-producing E. coli O111 and Cryptosporidium. Fewer juice-associated outbreaks have been reported since the juice HACCP regulation was implemented. Some juice operations that are exempt from processing requirements or do not comply with the regulation continue to be implicated in outbreaks of illness.     

An approach to reduction of uncertainties in internal doses reconstructed for the Techa River population

A methodology was developed for reduction of uncertainties in estimates of internal dose for residents of the Techa Riverside communities, who were exposed as a result of releases of radionuclides from the Mayak plutonium production facility in 1949-56. The 'Techa River Dosimetry System' (TRDS) was specifically elaborated for reconstruction of doses. A preliminary analysis of uncertainty for doses estimated using the current version of the TRDS showed large ranges in the uncertainty of internal absorbed dose and led to suggestions of methods to reduce uncertainties. The new methodological approaches described in this paper will allow for significant reduction of uncertainties of 90Sr-dose. The major sources of reduction are: making use of individual measured values of 90Sr and through development of a Household Registry to associate unmeasured persons with measured persons living in the same household(s).     

Optical sensors for the determination of concentrated hydroxide

An optical sensor system has been developed for the determination of concentrated strong bases ([OH-] = 1-10 M). The base sensors consist of SiO2/ZrO2-organic polymer composites and doped high-pKa indicators. Films were obtained by spin-casting these composite materials on glass substrates and were used as sensor elements for the spectrometric determination of hydroxide. The hydrophilic nature of the mixed oxide SiO2/ZrO2 and its chemical stability in concentrated alkali made it attractive as support in the composites. The organic polymers in the composites either provided better mechanical stability and dye immobilization or enhanced OH- diffusion and sensor response. The composite sensors showed a relative standard deviation of less than 2%. The response time of a SiO2/ZrO2-Nafion composite (sensor 2) was short (5 s), and a small hysteresis was observed during reproducibility measurements with 1-4 M NaOH solutions. The sensors were found to be stable in 4 M NaOH during a 30-day durability test, showing a standard deviation of 3.0-4.7%. The diffusion kinetics and hysteresis performance of the sensors were also evaluated.     

The 9-hexadecenoic and 11-octadecenoic acid content of natural fats and oils

The monoenoic methyl esters from numerous fats and oils which contained appreciablecis-9-hexadecenoic acid (cis-9-16∶1) were isolated by liquid-solid chromatography on silver nitrate-silica gel. Analysis of the monoenes by packed and capillary column gas-liquid chromatography showed that significant amounts ofcis-11-octadecenoic acid (cis-11-18∶1) were present in all samples. The amount ofcis-11-18∶1 found in the monoenoic methyl esters increased proportionally to logarithmic increases in thecis-9-16∶1 level. Most analyses reported in the literature also show this proportionality. This mathematical relationship suggests that chain elongation ofcis-9-16∶1 tocis-11-18∶1 is a biosynthetic pathway operative in a wide variety of species.