Towards a realistic in vitro experience of epidural Tuohy needle insertion.

The amount of pressure exerted on the syringe and the depth of needle insertion are the two key factors for successfully carrying out epidural procedure. The force feedback from the syringe plunger is helpful in judging the loss of pressure, and the depth of the needle insertion is crucial in identifying when the needle is precisely placed in the epidural space. This article presents the development of two novel wireless devices to measure these parameters to precisely guide the needle placement in the epidural space. These techniques can be directly used on patients or implemented in a simulator for improving the safety of procedure. A pilot trial has been conducted to collect depth and pressure data with the devices on a porcine cadaver. These measurements are then combined to accurately configure a haptic device for creating a realistic in vitro experience of epidural needle insertion

A Raman Microprobe Study of Corona Ageing in a Controlled Atmosphere

Raman microprobe spectroscopy is widely used in the analysis of polymers due to its high spatial resolution and its ability to characterise the exact chemical composition of a material and, for this reason, it can be applied to study electrical ageing in solid dielectrics. For example, it enables us to probe the chemical processes involved in electrical treeing, whereby solid polymer is converted into decomposition products through a number of electrical processes [1]. This study takes a novel approach to this problem through ex-situ experiments that seek to reproduce the chemistry of electrical treeing in bulk. Plaque specimens of a range of polymers, including polyethylene, polystyrene, PEEK and silicone rubber, were subjected to surface ageing via corona discharge, and the residual products on both the sample surface and the high voltage electrode (as seen in figure 1) were characterised by Raman microprobe spectroscopy. These experiments were performed as a function of applied voltage, electrode geometry etc both in air and within a closed cell that enabled the atmosphere to be controlled and adjusted. The resulting Raman fingerprints were compared with those previously identified within electrical trees [2,3]. After corona discharge was applied to the samples, despite a large change in surface texture, no residues were seen on the sample and few chemical changes were detected via Raman spectroscopy, thus implying that erosion of the material occurs by fragmentation of the polymer. Analysis of the electrodes aged in air and nitrogen, revealed varying evidence of sp2 hybridized carbon, and fluorescence, both of which are products previously associated with the processes involved in electrical treeing. The similarity in these results and previous published works [2,3] suggest that there are common processes involved between corona surface ageing and electrical treeing especially when an inert atmosphere is used

Ultraviolet and X-ray variability of NGC 4051 over 45 days with XMM-Newton and Swift

We analyse 15 XMM-Newton observations of the Seyfert galaxy NGC 4051 obtained over 45 days to determine the ultraviolet (UV) light curve variability characteristics and search for correlated UV/X-ray emission. The UV light curve shows variability on all time scales, however with lower fractional rms than the 0.2-10 keV X-rays. On days-weeks timescales the fractional variability of the UV is Fvar ~ 8%, and on short (~ hours) timescales Fvar ~ 2%. The within-observation excess variance in 4 of the 15 UV observations was found be much higher than the remaining 11. This was caused by large systematic uncertainties in the count rate masking the intrinsic source variance. For the four "good" observations we fit an unbroken power-law model to the UV power spectra with slope -2.0 +/- 0.5. We compute the UV/X-ray Cross-correlation function for the "good" observations and find a correlation of ~ 0.5 at time lag of ~ 3 ks, where the UV lags the X-rays. We also compute for the first time the UV/X-ray Cross-spectrum in the range 0-28.5 ks, and find a low coherence and an average time lag of ~ 3 ks. Combining the 15 XMM-Newton and the Swift observations we compute the DCF over +/-40 days but are unable to recover a significant correlation. The magnitude and direction of the lag estimate from the 4 "good" observations indicates a scenario where ~ 25 % of the UV variance is caused by thermal reprocessing of the incident X-ray emission.Comment: 11 pages, 8 figures. Accepted for publication in MNRA

The flux-dependent X-ray time lags in NGC 4051

We present an analysis of the X-ray time lags for the highly variable Seyfert 1 galaxy NGC 4051, based on a series of XMM-Newton observations taken in 2009. We investigate the Fourier frequency dependent time lags in the light curves between the 0.3--1.0 keV and 2.0--5.0 keV energy bands as a function of source flux, including simultaneous modelling of the resulting lag-frequency spectra. We find the shape of the lag-frequency spectra to vary significantly and systematically with source flux. We model the lag-frequency spectra using simple transfer functions, and find that two time lag components are required, one in each energy band. The simplest acceptable fits have only the relative contribution of the lagged component in the hard band varying with flux level, which can be associated with changes in the energy spectrum. We discuss the interpretation of these results in terms of the currently popular models for X-ray time lags.Comment: 9 pages, 4 figures. Accepted for publication in MNRA

Raman Microprobe Analysis of Electrical Treeing in Silicone Rubber

Previous papers have identified Raman microprobe analysis as a useful tool in the chemical analysis of electrical trees and have successfully applied the technique to trees grown in polyethylene. This paper comprises a detailed spectroscopic study of electrical trees grown in silicone rubber. A selection of trees of varying fractal dimensions were exposed using cryogenic microtomy and then the individual tree channels were subjected to surface specific Raman microprobe analysis. It was found that although some trees show that few chemical changes have occurred, some trees (including some where complete breakdown has occurred) show evidence of the presence of silica and carbon, the latter possibly originating from the side groups of the polymer chain. After this, some of the samples were then analyzed using scanning electron microscopy (SEM) to provide an alternative method of analysis and to reinforce the conclusions made. Results are discussed in comparison to previously published results from a similar analysis on trees in polyethylene

Economic and Social Planning Aims and Methods. ESRI Memorandum Series No. 114 1975

The questions which I shall seek to answer here are the following. What is economic planning and is there a need for such planning? What are the essential components of a plan, and what are therefore the major differences in the type of plans that may be proposed? May we learn anything from the practical planning experience of other countries? In answering these questions I propose to split up the discussion on the following lines - In Section II, a planning framework is set out In Section III, the relationship between macro-plans and certain investment projects is considered. Section IV examines the theory of indicative planning and the implementation of such plans in France and Japan. Finally, in Section V we discuss the problem of why some plans are successful, whilst others fail. In the title of this paper one may find the word "social"; I intend to salve my conscience at this stage by saying that I intend to interpret social as referring to the social impact of economic planning, and leave explicit concern of problems of planning for the elderly, the sick and other such service to the last speaker of this course

The Church Growth Movement: Offense to the Cross?

This is the Presidential Address to the American Society for Church Growth originally delivered in Pasadena, California, in November 1993. Dr. Vaughan’s seminal lecture served as the spark which ignited a new direction for our society that is gaining momentum each and every day

Church Grwoth Bibliography

This is a bibliography relevant for church growt

Church Grwoth Bibliography

This is a bibliography relevant for church growt