Anomalous dielectric response of very small quantities of virgin, aged and failed silicone oil

A technique is described for making dielectric spectroscopy measurements of very small quantities (<1μl) of oil. The technique utilises surface tension to hold the oil between the plates of a capacitor, the inter-electrode distance being controlled by a micrometer. Breakdown strength can also be estimated using this technique. Three samples of silicone oil, used in cable sealing ends, were tested: virgin, used and failed. A major component in the frequency dependent impedance had the form Z(ω)=B(1-b)(iω)/sup.1-p/). This component was interpreted in terms of a fractal percolation model, and the anomalous thickness dependence predicted by the model verified by varying the inter-electrode distance. The difference observed for the three different samples indicate that conducting contaminants are responsible for the percolation system

Sawing Recovery of Several Sawmills in Jepara

In the situation of wood material shortage, it is important to furniture manufacturers to efficiently utilize the wood. Increasing efficiency for improving value added of small medium enterprises of wood furniture industries in Jepara should be carried out from the first stage in wood processing: sawing that will convert logs into sawn timber. A study has been carried out on improving sawing recovery of sawntimber by live-sawing pattern to make loseware lumber for furniture material in Jepara region. This study was done by investigating the current sawing recovery data as determined during one full day's processing at each of the four bandsaw mill facilities and one chainsaw/carving facility. The results indicate that the current recovery rate of sawmilling services companies in Jepara reached 70 - 80 %. These recoveries are relatively high due to the live sawing pattern used and the fact that sawn boards were not edged or resawn into square pieces at the mill. Compared to existing rules and the Government standard for calculating the recovery rate, sawmilling service companies in Jepara have practiced efficient processing in sawing

The Moses–Littenberg meta-analytical method generates systematic differences in test accuracy compared to hierarchical meta-analytical models

AbstractObjectiveTo compare meta-analyses of diagnostic test accuracy using the Moses–Littenberg summary receiver operating characteristic (SROC) approach with those of the hierarchical SROC (HSROC) model.Study Design and SettingTwenty-six data sets from existing test accuracy systematic reviews were reanalyzed with the Moses–Littenberg model, using equal weighting (“E-ML”) and weighting by the inverse variance of the log DOR (“W-ML”), and with the HSROC model. The diagnostic odds ratios (DORs) were estimated and covariates added to both models to estimate relative DORs (RDORs) between subgroups. Models were compared by calculating the ratio of DORs, the ratio of RDORs, and P-values for detecting asymmetry and effects of covariates on DOR.ResultsCompared to the HSROC model, the Moses–Littenberg model DOR estimates were a median of 22% (“E-ML”) and 47% (“W-ML”) lower at Q*, and 7% and 42% lower at the central point in the data. Instances of the ML models giving estimates higher than the HSROC model also occurred. Investigations of heterogeneity also differed; the Moses–Littenberg models on average estimating smaller differences in RDOR.ConclusionsMoses–Littenberg meta-analyses can generate lower estimates of test accuracy, and smaller differences in accuracy, compared to mathematically superior hierarchical models. This has implications for the usefulness of meta-analyses using this approach. We recommend meta-analysis of diagnostic test accuracy studies to be conducted using available hierarchical model–based approaches

The radiobiological principles of boron neutron capture therapy: A critical review

The radiobiology of the dose components in a BNCT exposure is examined. The effect of exposure time in determining the biological effectiveness of γ-rays, due to the repair of sublethal damage, has been largely overlooked in the application of BNCT. Recoil protons from fast neutrons vary in their relative biological effectiveness (RBE) as a function of energy and tissue endpoint. Thus the energy spectrum of a beam will influence the RBE of this dose component. Protons from the neutron capture reaction in nitrogen have not been studied but in practice protons from nitrogen capture have been combined with the recoil proton contribution into a total proton dose. The relative biological effectiveness of the products of the neutron capture reaction in boron is derived from two factors, the RBE of the short range particles and the bio-distribution of boron, referred to collectively as the compound biological effectiveness factor. Caution is needed in the application of these factors for different normal tissues and tumors.Fil: Hopewell, J. W.. University of Oxford; Reino UnidoFil: Morris, G. M.. Brookhaven National Laboratory; Estados UnidosFil: Schwint, Amanda Elena. Comision Nacional de Energia Atomica. Gerencia de Area de Aplicaciones de la Tecnología Nuclear; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Coderre, J. A.. No especifíca

Compression stockings for preventing deep vein thrombosis (DVT) in airline passengers

Background Air travel might increase the risk of deep vein thrombosis (DVT). It has been suggested that wearing compression stockings might reduce this risk. This is an update of the review first published in 2006. Objectives To assess the effects of wearing compression stockings versus not wearing them for preventing DVT in people travelling on flights lasting at least four hours. Search methods The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL and AMED databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 1 April 2020. We also checked the bibliographies of relevant studies and reviews identified by the search to check for any additional trials. Selection criteria Randomised trials of compression stockings versus no stockings in passengers on flights lasting at least four hours. Trials in which passengers wore a stocking on one leg but not the other, or those comparing stockings and another intervention were also eligible. Data collection and analysis Two review authors independently selected trials for inclusion and extracted data. We sought additional information from trialists where necessary. Main results One new study that fulfilled the inclusion criteria was identified for this update. Twelve randomised trials (n = 2918) were included in this review: ten (n = 2833) compared wearing graduated compression stockings on both legs versus not wearing them; one trial (n = 50) compared wearing graduated compression tights versus not wearing them; and one trial (n = 35) compared wearing a graduated compression stocking on one leg for the outbound flight and on the other leg on the return flight. Eight trials included people judged to be at low or medium risk of developing DVT (n = 1598) and two included high‐risk participants (n = 1273). All flights had a duration of more than five hours. Fifty of 2637 participants with follow‐up data available in the trials of wearing compression stockings on both legs had a symptomless DVT; three wore stockings, 47 did not (odds ratio (OR) 0.10, 95% confidence interval (CI) 0.04 to 0.25, P Authors' conclusions There is high‐certainty evidence that airline passengers similar to those in this review can expect a substantial reduction in the incidence of symptomless DVT and low‐certainty evidence that leg oedema is reduced if they wear compression stockings. The certainty of the evidence was limited by the way that oedema was measured. There is moderate‐certainty evidence that superficial vein thrombosis may be reduced if passengers wear compression stockings. We cannot assess the effect of wearing stockings on death, pulmonary embolism or symptomatic DVT because no such events occurred in these trials. Randomised trials to assess these outcomes would need to include a very large number of people

Publication bias in clinical trials

This is the protocol for a review and there is no abstract. The objectives are as follows: To summarise evidence of publication bias for trials of health care interventions.Output Type: Protoco