Estimation of safe exposure time from an ophthalmic operating microscope with regard to ultraviolet radiation and blue-light hazards to the eye

Hazards from the optical radiation of an operating microscope that cause damage at the corneal, lenticular, and retinal levels were investigated; we considered, in particular, ultraviolet radiation (UVR) and blue light. The spectral irradiance from a Zeiss operation microscope OPMI VISU 200 was measured in the corneal plane between 300 and 1100 nm. Effective irradiance and radiance were calculated with relative spectral effectiveness data from the American Conference for Governmental and Industrial Hygienists. Safe exposure time to avoid UVR injury to the lens and cornea was found to be 2 h without a filter, 4 h with a UVR filter, 200 a yellow filter, and 400 h with a filter combination. Safe exposure time to avoid retinal photochemical injury was found to be 3 min without a filter and with a UVR filter, 10 min with a yellow filter, and 49 min with a filter combination. The effective radiance limit for retinal thermal injury was not exceeded. The hazard due to the UVR component from the operating microscope is not critical, and operation time can be safely prolonged with the use of appropriate filters. The retinal photochemical hazard appears critical without appropriate filters, permitting only some minutes of safe exposure time. The calculated safe exposure times are for worst-case conditions and maximal light output and include a safety factor.     

Comparative evaluation of chloroethene dechlorination to ethene by Dehalococcoides-like microorganisms

Reductive dehalogenation of tetrachloroethene (PCE), trichloroethene (TCE), cis-1,2-dichloroethene (DCE), and vinyl chloride (VC) was examined in four cultures containing Dehalococcoides-like microorganisms. Dechlorination and growth kinetics were compared using a Monod growth-rate model for multiple electron acceptor usage with competition. Included were the Victoria mixed culture containing Dehalococcoides species strain VS (from Victoria, TX), the mixed culture KB-1/VC (from southern Ontario), the Pinellas mixed culture (from Pinellas, FL), and D. ethenogenes strain 195. All cultures, with the exception of D. ethenogenes strain 195, grew with VC as catabolic electron acceptor. A dilution method was developed that allows a valid comparison to be made of dehalogenating kinetics between different mixed cultures. Using this procedure, maximum growth rates on VC were found to be similar for strain VS and KB-1/VC (0.42-0.49 +/- 0.02 d(-1)) but slower for the Pinellas culture (0.28 +/- 0.01 d(-1)). The 16S rRNA gene sequences were determined to ensure that no cross contamination between cultures had occurred. Following enrichment of the VC dechlorinating microorganisms on VC, the cultures were amended with DCE, TCE, or PCE. The three mixed cultures failed to dechlorinate PCE or did so very slowly. However, the dilution technique indicated that all experienced growth on TCE and DCE as well as on VC. Maximum growth rates on DCE alone were quite similar (0.43-0.46 d(-1)), while the Pinellas culture grew faster on TCE alone (0.49 d(-1)) than did the other two mixed cultures (0.33-0.35 d(-1)). Half-velocity and inhibition constants for growth on TCE were also determined for the three mixed cultures; both constants were found to be essentially equal and the same for the different cultures, varying between only 8.6 and 10.5 microM. The ability of the strain VS, KB-1/VC, and Pinellas cultures to utilize TCE rapidly with conversion to ethene is quite different from that of any other reported microorganism. It was separately confirmed with more traditional cell-counting techniques that strain VS coupled TCE, as well as DCE and VC, utilization with growth. This is the first report of an organism obtaining energy for growth through every step in the reduction of TCE to ethene. Also, as suggested by the dilution technique, the dehalogenating organisms in the KB-1/VC and Pinellas cultures appear to obtain growth from TCE utilization as well. Such ability to grow while dehalogenating TCE to ethene will be an important advantage for their use in bioaugmentation.     

Structural relationships between measures based on heart beat intervals: potential for improved risk assessment

Decreased left ventricular ejection fraction is the most commonly used risk factor for identification of patients at high-risk for lethal ventricular arrhythmic events. Twenty-four-hour electrocardiographic (ECG) approaches to risk stratification include: counts of ventricular premature contractions (VPCs), measures of heart rate variability (HRV), and heart rate turbulence (HRT) which has two components, turbulence onset and turbulence slope (TS). Refinement of these ECG risk stratifiers could enhance their clinical utility. We explored the structural relationships between heart rate (HR) and HRV and HRT measures. Our goal was to separate out the component of these measures due to the underlying average heart rate (HR), thus potentially reducing the variability of the measures and increasing their power to stratify risk. We proposed re-scaling tachograms of heart-beat intervals so that the re-scaled tachogram has a HR of 75 (or equivalently an average interval of 800 ms) and calculating HRV and HRT from the rescaled time series. We also explored the relationship between the number of VPCs and HRT. We showed that TS is structurally related to the number of VPCs (and hence to the length of the ECG recording). We proposed an adjusted TS that is independent of the number of VPCs. We also addressed the ability of shorter ECG recording to estimate HRV and HRT measures. We evaluated standard and rescaled HRV and HRT measures using qualifying ambulatory ECG recordings from 744 patients in the Cardiac Arrhythmia Suppression Trial. We found that measures based on the rescaled tachogram had reduced variance (20% to 40%). Correlations between measures were also substantially reduced. We also found substantial circadian effects on some, but not all HRV indices, not explained by the circadian pattern in HR and possibly pointing to additional measures for risk prediction. In conclusion, we found that adjusting for HR and the number of VPCs in heart-beat related ambulatory ECG measures has the potential to significantly improve the power of these measures to risk stratify cardiac patients.     

Determination of primary particle size distributions from time-resolved laser-induced incandescence measurements

For a polydisperse nanoparticle ensemble the evaluation of time-resolved laser-induced incandescence (LII) measurements yields a weighted average value for the primary nanoparticle size. Although this value is sufficient for narrow size distributions, a comprehensive characterization of a particle-evolution process requires the reconstruction of the size distribution. An easy-to-use online approach is presented to evaluate the LII signal regarding higher moments of the distribution. One advantage of this approach is that the size distribution results in a deceleration of the LII signal decay with time after the laser pulse. Therefore LII signal-decay curves are evaluated in two different time intervals after the laser pulse, providing information about the desired distribution parameters that has been tested successfully with experimental curves taken in different soot-formation processes.     

A comparison of actual and paper-and-pencil versions of the water jar test of rigidity.

Rigidity, as measured by the paper-and-pencil water jar test and actual presence of the jars, were not found to be highly related. The paper-and-pencil version was found to elicit more behavior categorized as rigid. The results were interpreted as not favoring either measure as an adequate measure of rigidity, but of problem solving ability. From Psyc Abstracts 36:04:4CE91W. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comportement anodique de Ga(As1-txPx) sous illumination

The anodic behaviour of Ga(As_1-xP_x) in basic media and under illumination has been investigated by measuring the electrode characteristics and the interfacial capacity values. These measurements are interpreted using Gärtner's classical model. The diffusion length of minority carriers and the gap value have been calculated. It is necessary to assume a recombination on the surface to explain the variation to the photolyse current density with the potential. This process may be attributed to a centre for which it has been possible to evaluate the energy level.     

MITNYS-II?A Digital Program for On-Line Analysis of Nystagmus

A digital computer program, MITNYS-II, has been developed for on-line analysis of nystagmus which results from visual, vestibular or caloric stimulation. The program accepts sampled records of eye position and yields cumulative slow phase position, slow phase velocity, instantaneous fast phase frequency and other parameters in 25 ms. In this paper the algorithms by which fast phases are detected, and by which slow phase cumulative eye position is extrapolated across the fast phase interval are described. Extensive tests with vestibular, optokinetic and caloric nystagmus yield reliability figures of the order of 2% for false identification of fast phases and missed fast phases. MITNYS-II has been successfully employed to interpret clinical EOG records, examples of which are presented.     

Der Zerfall von Mischkristallen des Wüstits Fe1–xO mit drei- und höherwertigen Kationen bei 200 bis 650 °C

Untersuchung (röntgenographisch, mikroskopisch und mit der Mikrosonde) des Zerfalls von Wüstitmischkristallen mit Zusatz von Aluminium-, Silizium(IV)-, Phosphor(V)- oder Chrom(III)-oxyd nach isothermischem Halten swischen 200 und 650 °C. Einfluß der Temperatur, der Haltezeit und der Art des Zusatzoxydes auf den Wüstitzerfall. Erörterung und Deutung der Versuchsergebnisse über den Zerfallsablauf mit seinen verschiedenen Teilschritten.     

Die Stoßwellen beim Bruch langer Zugproben und ihr Einfluß auf die Gleichmaßdehnung

Zugversuche an langen Proben aus Spannstahl 145/160 mit rd. 0,45% C, 1,5% Si, 0,6% Mn, 0,4% Cr und 0,15% Cu und Ermittlung der Oleichmaßdehnung unter der Höchstkraft und nach dem Bruch. Messung der Stauchung und Aufnahme der hoch- und niederfrequenten Stoßwellen beim Bruch.     

A Distributed Ant Algorithm for\protect Efficiently Patrolling a Network

We consider the problem of patrolling—i.e. ongoing exploration of a network by a decentralized group of simple memoryless robotic agents. The model for the network is an undirected graph, and our goal, beyond complete exploration, is to achieve close to uniform frequency of traversal of the graphs edges. A simple multi-agent exploration algorithm is presented and analyzed. It is shown that a single agent following this procedure enters, after a transient period, a periodic motion which is an extended Eulerian cycle, during which all edges are traversed an identical number of times. We further prove that if the network is Eulerian, a single agent goes into an Eulerian cycle within 2|E|D steps, |E| being the number of edges in the graph and D being its diameter. For a team of k agents, we show that after at most 2( 1 + 1/k) |E|D steps the numbers of edge visits in the network are balanced up to a factor of two. In addition, various aspects of the algorithm are demonstrated by simulations.