Relationship of oxygen tension to viral disease Final report

Tissue culture development for isolation and quantization of lymphocytic choriomeningitis viru

Performance of Hollow Load Process Challenge Devices (HLPCDs) for the determination of air removal and steam penetration in porous load steam sterilization processes: Part 1 – The evolution of HLPCDs in standards and a review of the current supporting published evidence

Steam sterilization Process Challenge Devices (PCDs) are devices which present a defined challenge to a sterilization process. In part one of a two part series the authors review the published literature covering studies evaluating the removal of air and penetration of steam into hollow tubular devices and then discuss the relevance of the material in support of the current custom and practice of utilising simple tubular PCDs (Hollow Load Process Challenge Devices HLPCDs) as a means of monitoring production loads for adequacy of air removal and steam penetration. This review places such data in the context of the evolution of HLPCDs in the standards for small and large porous load steam sterilizers. With regard to the apparent acceptance of the HLPCD in EN 867-5 into custom and practice for batch monitoring the literature suggests this may be misleading. The literature review concludes that there is an urgent need for an International Standard which describes how a HLPCD can be developed and tested against real medical devices in a range of sterilization processes representing current state of the art in full load conditions

Free-Flight Tests of Fifth-Stage Scout Entry Vehicle at Mach Numbers of 5 and 17

Measurements have been made in air at two Mach numbers of the static stability, normal force, and drag of a version of the fifth-stage Scout entry vehicle. The most significant result was that the design center of gravity led to a condition of static instability at small angles of attack at Mach number 17. At this Mach number, the static stability was a highly nonlinear function of the angle of attack. A useful method for analyzing free-flight data having this nonlinear behavior is included in this report. Comparisons were made between the measured aerodynamic coefficients and those estimated by Newtonian impact theory and by a method developed by Seiff and Whiting. The latter method gave good estimates of the normal-force-curve slope at both Mach numbers and of the moment-curve slope at the lower Mach number. It resulted in an overestimation of the static stability at Mach number 17, although it gave results decidedly closer to the experimental value than did Newtonian impact theory

The Collapse of the Soviet Union and the Productivity of American Mathematicians

It has been difficult to open up the black box of knowledge production. We use unique international data on the publications, citations, and affiliations of mathematicians to examine the impact of a large post-1992 influx of Soviet mathematicians on the productivity of their American counterparts. We find a negative productivity effect on those mathematicians whose research overlapped with that of the Soviets. We also document an increased mobility rate (to lower-quality institutions and out of active publishing) and a reduced likelihood of producing “home run” papers. Although the total product of the pre-existing American mathematicians shrank, the Soviet contribution to American mathematics filled in the gap. However, there is no evidence that the Soviets greatly increased the size of the “mathematics pie.” Finally, we find that there are significant international differences in the productivity effects of the collapse of the Soviet Union, and that these international differences can be explained by both differences in the size of the émigré flow into the various countries and in how connected each country is to the global market for mathematical publications.

A Shred of Credible Evidence on the Long Run Elasticity of Labor Supply

The available estimates of the wage elasticity of male labor supply in the literature have varied between -0.2 and 0.2, implying that permanent wage increases have relatively small, poorly determined effects on labor supplied. The variation in existing estimates calls for a simple, natural experiment in which men can change their hours of work, and in which wages have been exogenously and permanently changed. We introduce a panel data set of taxi drivers who choose their own hours, and who experienced two exogenous permanent fare increases instituted by the New York City Taxi and Limousine Commission. Our preferred estimate suggests that their elasticity of labor supply is about -0.2.male labor supply, effect of wage rates, long run labor supply, public policies, taxation, social safety nets, and redistribution of income, New York City Taxi and Limousine Commission

LANNDD---A Massive Liquid Argon Detector for Proton Decay, Supernova and Solar Neutrino Studies, and a Neutrino Factory Detector

We describe a possible Liquid Argon Neutrino and Nuclear Decay Detector (LANNDD) that consists of a 70kt magnetized liquid argon tracking detector. The detector is being designed for the Carlsbad Underground Laboratory.Comment: 8 pages, 5 figures; for the Neutrino Facory Meeting at KEK-NUFACT '0

Failure of non-vacuum steam sterilization processes for dental handpieces

Background: Dental handpieces are used in critical and semi-critical operative interventions. Although a number of dental professional bodies recommend that dental handpieces are sterilized between patient use there is a lack of clarity and understanding of the effectiveness of different steam sterilization processes. The internal mechanisms of dental handpieces contain narrow lumens (0·8-2·3mm) which can impede the removal of air and ingress of saturated steam required to achieve sterilization conditions. Aim: To identify the extent of sterilization failure in dental handpieces using a non-vacuum process. Methods: In-vitro and in-vivo investigations were conducted on commonly used UK benchtop steam sterilizers and three different types of dental handpieces. The sterilization process was monitored inside the lumens of dental handpieces using thermometric (TM) methods (dataloggers), chemical indicators (CI) and biological indicators (BI). Findings: All three methods of assessing achievement of sterility within dental handpieces that had been exposed to non-vacuum sterilization conditions demonstrated a significant number of failures (CI=8/3,024(fails/n tests); BI=15/3,024; TM=56/56) compared to vacuum sterilization conditions (CI=2/1,944; BI=0/1,944; TM=0/36). The dental handpiece most likely to fail sterilization in the non-vacuum process was the surgical handpiece. Non-vacuum sterilizers located in general dental practice had a higher rate of sterilization failure (CI=25/1,620; BI=32/1,620; TM=56/56) with no failures in vacuum process. Conclusion: Non-vacuum downward/gravity displacement, type-N steam sterilizers are an unreliable method for sterilization of dental handpieces in general dental practice. The handpiece most likely to fail sterilization is the type most frequently used for surgical interventions

Investigating steam penetration using thermometric methods in dental handpieces with narrow internal lumens during sterilizing processes with non-vacuum or vacuum processes

Background: Dental handpieces are required to be sterilized between patient use. Vacuum steam sterilization processes with fractionated pre/post-vacuum phases or unique cycles for specified medical devices, are required for hollow instruments with internal lumens to assure successful air removal. Entrapped air will compromise achievement of required sterilization conditions. Many countries and professional organisations still advocate non-vacuum sterilization processes for these devices. Aim: To investigate non-vacuum downward/gravity displacement, type-N steam sterilization of dental handpieces, using thermometric methods to measure time to achieve sterilization temperature at different handpiece locations. Methods: Measurements at different positions within air turbines were undertaken with thermocouples and dataloggers. Two examples of commonly used UK benchtop steam sterilizers were tested; a non-vacuum benchtop sterilizer (Little Sister 3, Eschmann, UK) and a vacuum benchtop sterilizer (Lisa, W&H, Austria). Each sterilizer cycle was completed with three handpieces and each cycle in triplicate. Findings: A total of 140 measurements inside dental handpiece lumens were recorded. We demonstrate that the non-vacuum process fails (time range 0-150 seconds) to reliably achieve sterilization temperatures within the time limit specified by the International standard (15 seconds equilibration time). The measurement point at the base of the handpiece failed in all test runs (n=9) to meet the standard. No failures were detected with the vacuum steam sterilization type B process with fractionated pre-vacuum and post-vacuum phases. Conclusion: Non-vacuum downward/gravity displacement, type-N steam sterilization processes are unreliable in achieving sterilization conditions inside dental handpieces and the base of the handpiece is the site most likely to fail