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A Butler

Publications and source records attributed to A Butler.

At least 19 recordsLinked to original sources
PubMed2006

Action and object processing in aphasia: from nouns and verbs to the effect of manipulability.

The processing of words and pictures representing actions and objects was tested in 21 aphasic patients and 20 healthy controls across three word production tasks: picture-naming (PN), single word reading (WR) and word repetition (WRP). Analysis 1 targeted task and lexical category (noun-verb), revealing worse performance on PN and verb items for both patients and control participants. For Analysis 2 we used data collected in a concurrent gesture norming study to re-categorize the noun-verb items along hand imagery parameters (i.e., objects that can/cannot be manipulated and actions which do/do not involve fine hand movements). Here, patients displayed relative difficulty with the 'manipulable' items, while controls displayed the opposite pattern. Therefore, whereas the noun-verb distinction resulted simply in lower verb accuracy across groups, the 'manipulability' distinction revealed a 'double-dissociation' between patients and control participants. These results carry implications for theories of embodiment, lexico-semantic dissociations, and the organization of meaning in the brain.

Adult↗
PubMed2006

Which radiological investigations should be performed to identify fractures in suspected child abuse?

AIMS: To determine which radiological investigations should be performed and which children should be investigated. MATERIALS AND METHODS: An all language literature search of original articles; from 1950-October 2005. Two reviewers independently reviewed each article. A third was carried out on disagreement. Each study was assessed using standardised data extraction, critical appraisal and evidence forms. RESULTS: Thirty-four studies were included. Fifteen addressed the question: which investigation has a higher yield, skeletal surveys (SS) or bone scintigraphy (BS)? Studies gave conflicting results. Overall neither investigation is as good as the two combined. BS predominately missed skull, metaphyseal and epiphyseal fractures, whereas SS commonly missed rib fractures. Two studies showed that a repeat SS 2 weeks after the initial study provided significant additional information about tentative findings, the number and age of fractures. A comparative study evaluated additional oblique views of ribs in 73 children and showed improved diagnostic sensitivity, specificity and accuracy. Four studies addressed the diagnostic yield for occult fractures with respect to age. This was significant for children under 2-years old. CONCLUSIONS: In children under 2-years old, where physical abuse is suspected, diagnostic imaging of the skeleton should be mandatory. SS or BS alone is inadequate to identify all fractures. It is recommended that all SS should include oblique views of the ribs. This review suggests that the following options would optimize the diagnostic yield. However, each needs to be evaluated prospectively: SS that includes oblique views, SS and BS, a SS with repeat SS or selected images 2 weeks later or a BS plus skull radiography and coned views of metaphyses and epiphyses.

Adolescent↗
PubMed2006

Information about liver transplantation on the World Wide Web.

Orthotopic liver transplant (OLTx) has evolved to a successful surgical management for end-stage liver diseases. Awareness and information about OLTx is an important tool in assisting OLTx recipients and people supporting them, including non-transplant clinicians. The study aimed to investigate the nature and quality of liver transplant-related patient information on the World Wide Web. Four common search engines were used to explore the Internet by using the key words 'Liver transplant'. The URL (unique resource locator) of the top 50 returns was chosen as it was judged unlikely that the average user would search beyond the first 50 sites returned by a given search. Each Web site was assessed on the following categories: origin, language, accessibility and extent of the information. A weighted Information Score (IS) was created to assess the quality of clinical and educational value of each Web site and was scored independently by three transplant clinicians. The Internet search performed with the aid of the four search engines yielded a total of 2,255,244 Web sites. Of the 200 possible sites, only 58 Web sites were assessed because of repetition of the same Web sites and non-accessible links. The overall median weighted IS was 22 (IQR 1 - 42). Of the 58 Web sites analysed, 45 (77%) belonged to USA, six (10%) were European, and seven (12%) were from the rest of the world. The median weighted IS of publications originating from Europe and USA was 40 (IQR = 22 - 60) and 23 (IQR = 6 - 38), respectively. Although European Web sites produced a higher weighted IS [40 (IQR = 22 - 60)] as compared with the USA publications [23 (IQR = 6 - 38)], this was not statistically significant (p = 0.07). Web sites belonging to the academic institutions and the professional organizations scored significantly higher with a median weighted IS of 28 (IQR = 16 - 44) and 24(12 - 35), respectively, as compared with the commercial Web sites (median = 6 with IQR of 0 - 14, p = .001). There was an Intraclass Correlation Coefficient (ICC) of 0.89 and an associated 95% CI (0.83, 0.93) for the three observers on the 58 Web sites. The study highlights the need for a significant improvement in the information available on the World Wide Web about OLTx. It concludes that the educational material currently available on the World Wide Web about liver transplant is of poor quality and requires rigorous input from health care professionals. The authors suggest that clinicians should pay more attention to take the necessary steps to improve the standard of information available on their relevant Web sites and must take an active role in helping their patients find Web sites that provide the best and accurate information specifically applicable to the loco-regional circumstances.

Humans↗
PubMed2006

Lyon Playfair (1818-1898) and compulsory vaccination.

Lyon Playfair was born in India but brought up by his uncle in St Andrews. He studied medicine in Glasgow and Edinburgh but never practised as a doctor. Instead he worked for the chemist Thomas Graham in London and then studied for a PhD with Liebig in Germany. While serving on a government commission he became very interested in public health, particularly the control of infectious diseases. In 1883, while a member of parliament, he made a passionate speech in support of a government bill in favour of compulsory vaccination against smallpox. He was violently attacked for his speech in a pamphlet by William White, an adherent of the teachings of the Swedish mystic Emanuel Swedenborg. Playfair died in 1898 and is buried in St Andrews.

History, 19th Century↗
PubMed2005

Selective use of ultrasonographic vascular mapping in the assessment of patients before haemodialysis access surgery.

BACKGROUND: Use of routine preoperative ultrasonography to determine the optimum site for haemodialysis access surgery increases the number of distal arteriovenous fistulas formed and improves overall patency rates. Nevertheless its use in all patients is time consuming and costly. This study examined whether clinical parameters could be used to determine the requirement for preoperative ultrasonography. METHODS: Between March 2002 and October 2003, 145 consecutive patients were reviewed in the vascular access clinic. Patients were first assessed clinically, a site for vascular access surgery was proposed, and the need for radiological mapping studies recorded. A second, blinded, clinician determined the site for vascular access surgery using ultrasonography. The correlation between clinical and ultrasonographic findings was then examined. RESULTS: Ultrasonography was considered unnecessary using clinical criteria in 106 patients. Subsequent ultrasonographic mapping altered the management of only one patient. In contrast, the management of 18 of the 39 patients in whom ultrasonography was thought necessary was influenced by radiological imaging. A 1-year primary patency rate of 77.0 per cent was achieved following vascular access surgery on the study population. CONCLUSION: Clinical parameters could be used to determine the need for preoperative vascular ultrasonographic mapping; imaging was not required in the majority of patients.

Adolescent↗
PubMed2005

Preimplantation diagnosis of a lysosomal storage disorder by in situ enzymatic activity: 'proof of principle' in acid sphingomyelinase-deficient mice.

Genetic diagnosis of preimplantation embryos (PGD) can substantially reduce the chance that at-risk couples have children afflicted with inherited diseases. However, PGD requires DNA,which is usually obtained from single cells following embryo biopsy. In addition, PGD requires that the genetic defect(s) causing the disorder be known. We have therefore developed an alternative to PGD, which we term preimplantation enzymatic diagnosis (PED). PED has several advantages over PGD, including the facts that it does not require embryo biopsy and that the gene defect(s) causing the disorder need not be known. We have demonstrated 'proof of principle' for this approach using embryos obtained from a mouse model (ASMKO mice) of acid sphingomyelinase (ASM)-deficient Niemann-Pick disease, an inherited lysosomal storage disorder. For this technique, fluorescently (BODIPY)-conjugated sphingomyelin was used to detect ASM activity in situ. Wild-type, preimplantation embryos degraded the substrate following a short 'pulse-chase' period, resulting in markedly reduced fluorescence compared to ASMKO embryos, which retained the fluorescent substrate. Thus, the two embryo types could be easily distinguished by fluorescent microscopy. The fluorescent sphingomyelin was not toxic to the embryos, and the entire procedure could be accomplished within 48 h without embryo biopsy. We suggest that PED may be useful for the preimplantation diagnosis of lysosomal storage disorders, and perhaps other enzymatic defects where similar in situ assay methods are available.

Animals↗
PubMed2005

Aircrew dosimetry using the Predictive Code for Aircrew Radiation Exposure (PCAIRE).

During 2003, a portable instrument suite was used to conduct cosmic radiation measurements on 49 jet-altitude flights, which brings the total number of in-flight measurements by this research group to over 160 flights since 1999. From previous measurements, correlations have been developed to allow for the interpolation of the dose-equivalent rate for any global position, altitude and date. The result was a Predictive Code for Aircrew Radiation Exposure (PCAIRE), which has since been improved. This version of the PCAIRE has been validated against the integral route dose measurements made at commercial aircraft altitudes during the 49 flights. On most flights, the code gave predictions that agreed to the measured data (within +/- 25%), providing confidence in the use of PCAIRE to predict aircrew exposure to galactic cosmic radiation. An empirical correlation, based on ground-level neutron monitoring data, has also been developed for the estimation of aircrew exposure from solar energetic particle (SEP) events. This model has been used to determine the significance of SEP exposure on a theoretical jet altitude flight during GLE 42.

Aerospace Medicine↗
PubMed2004

Assessment of aircrew radiation exposure by further measurements and model development.

A methodology is presented for collecting and analysing exposure measurements from galactic cosmic radiation using a portable equipment suite and encapsulating these data into a semi-empirical model/Predictive Code for Aircrew Radiation Exposure (PCAIRE) for the assessment of aircrew radiation exposure on any flight over the solar cycle. The PCAIRE code has been validated against integral route dose measurements at commercial aircraft altitudes during experimental flights made by various research groups over the past 5 y with code predictions typically within +/-20% of the measured data. An empirical correlation, based on ground-level neutron monitoring data, is detailed further for estimation of aircrew exposure from solar particle events. The semi-empirical models have been applied to predict the annual and career exposure of a flight crew member using actual flight roster data, accounting for contributions from galactic radiation and several solar energetic-particle events over the period 1973-2002.

Aerospace Medicine↗
PubMed2003

Dissection of K+ currents in Caenorhabditis elegans muscle cells by genetics and RNA interference.

GFP-promoter experiments have previously shown that at least nine genes encoding potassium channel subunits are expressed in Caenorhabditis elegans muscle. By using genetic, RNA interference, and physiological techniques we revealed the molecular identity of the major components of the outward K+ currents in body wall muscle cells in culture. We found that under physiological conditions, outward current is dominated by the products of only two genes, Shaker (Kv1) and Shal (Kv4), both expressing voltage-dependent potassium channels. Other channels may be held in reserve to respond to particular circumstances. Because GFP-promoter experiments indicated that slo-2 expression is prominent, we created a deletion mutant to identify the SLO-2 current in vivo. In both whole-cell and single-channel modes, in vivo SLO-2 channels were active only when intracellular Ca2+ and Cl- were raised above normal physiological conditions, as occurs during hypoxia. Under such conditions, SLO-2 is the largest outward current, contributing up to 87% of the total current. Other channels are present in muscle, but our results suggest that they are unlikely to contribute a large outward component under physiological conditions. However, they, too, may contribute currents conditional on other factors. Hence, the picture that emerges is of a complex membrane with a small number of household conductances functioning under normal circumstances, but with additional conductances that are activated during unusual circumstances.

Animals↗
PubMed2003

Demonstration of a collisionally excited optical-field-ionization XUV laser driven in a plasma waveguide.

We describe the first demonstration of a collisionally excited optical-field-ionization laser driven within a waveguide. Lasing on the 4d(9)5d-4d(9)5p transition at 41.8 nm in Xe8+ was observed to be closely correlated to conditions under which the pump laser pulses were guided well by a gas-filled capillary discharge waveguide. Simulations of the propagation of the pump laser radiation show that gain was achieved over essentially the whole 30 mm length of the waveguide.

Journal Article↗
PubMed2003

The effect of two nonresorbable suture types on the mechanical performance over a metal suture anchor eyelet.

An understanding of the mechanical properties of different suture materials is valuable when selecting the most appropriate suture and repair technique. Sutures should be strong, easy to handle and have high knot security. The introduction of suture anchors adds an additional variable regarding the effect of stress risers over the eyelet. Improving the mechanical properties of a suture may be a possible method to help avoid failure over stress risers such as the eyelet of suture anchor. This study examined the static and viscoelastic properties of a new polyethylene based non-resorbable suture (Fibrewire) over the eyelet of a standard anchor compared to braid polyester non-resorbable suture (Ethibond). Fibrewire had superior ultimate load properties compared to Ethibond (360.2 N+/-23.8 vs 191.9 N+/-17.3) as well as greater stiffness (61.3 N/mm+/-9.7 vs 8.1 N/mm+/-0.4) when tested in uniaxial tension through a metal anchor eyelet (Mitek) ( p<0.001). Fibrewire demonstrated greater stress relaxation than Ethibond ( p<0.05). Differences in the static and viscoelastic properties of suture may have implications in the post-operative period or during rehabilitation.

Equipment Failure Analysis↗
PubMed2003

Setting up a quality assurance program in endoscopy.

BACKGROUND: Both patients and government demand proof of quality of care and value for money. Our unit ist in a large teaching hospital, performing over 6000 procedures per year. We have designed and implemented a Quality Assurance (QA) program, the basis of which we believe could be a model for endoscopy QA. METHODS: A QA team was formed and a literature search undertaken. An initial 3 month audit was then performed into indications for, and complications of, all procedures. The results of this initial audit led us to concentrate on colonoscopy and ERCP. The specific items of data collected were based on the "Core Quality Indicators" developed by the American Society for Gastrointestinal Endoscopy (ASGE). We also analysed data relating to endoscope disinfection, equipment failure and carried out a patient satisfaction survey. The data were presented at 3-monthly QA meeting, and appropriate action taken. RESULT: We performed a detailed audit of ERCP (217 procedures) and colonoscopy (904 procedures). Patients risk was stratified using the American Society of Anaesthesiology (ASA) classification. Using these data we established our technical success and complication rates for colonoscopy and ERCP. Audit of equipment revealed that on average an endoscope was away for repair 9 % of the time. Contamination of endoscopes was frequent with glutaraldehyde disinfection; the rate of contamination fell dramatically when we changed our disinfection method. CONCLUSION: A QA program can be implemented in busy endoscopy units. There are significant problems, however, in ensuring that such a program is effective: these include inadequate funding/staffing, lack of suitable information technology and lack of clear guidelines for dealing with poor performance.

Endoscopy↗
PubMed2002

Guiding of high-intensity laser pulses with a hydrogen-filled capillary discharge waveguide.

We report guiding of laser pulses with peak input intensities greater than 10(17) W cm(-2) in 30 mm and 50 mm long H2-filled capillary discharge waveguides. Under conditions producing good guiding the coupling and propagation losses of the waveguide were <4% and (7+/-1) m(-1), respectively. The spectra of the transmitted pulses were not broadened significantly, but were shifted to shorter wavelength. It is concluded that this shift is not associated with significant temporal distortion of the laser pulse.

Journal Article↗
PubMed2002

Galactic and solar radiation exposure to aircrew during a solar cycle.

An on-going investigation using a tissue-equivalent proportional counter (TEPC) has been carried out to measure the ambient dose equivalent rate of the cosmic radiation exposure of aircrew during a solar cycle. A semi-empirical model has been derived from these data to allow for the interpolation of the dose rate for any global position. The model has been extended to an altitude of up to 32 km with further measurements made on board aircraft and several balloon flights. The effects of changing solar modulation during the solar cycle are characterised by correlating the dose rate data to different solar potential models. Through integration of the dose-rate function over a great circle flight path or between given waypoints, a Predictive Code for Aircrew Radiation Exposure (PCAIRE) has been further developed for estimation of the route dose from galactic cosmic radiation exposure. This estimate is provided in units of ambient dose equivalent as well as effective dose, based on E/H x (10) scaling functions as determined from transport code calculations with LUIN and FLUKA. This experimentally based treatment has also been compared with the CARI-6 and EPCARD codes that are derived solely from theoretical transport calculations. Using TEPC measurements taken aboard the International Space Station, ground based neutron monitoring, GOES satellite data and transport code analysis, an empirical model has been further proposed for estimation of aircrew exposure during solar particle events. This model has been compared to results obtained during recent solar flare events.

Aerospace Medicine↗
PubMed2001

Simulations of a hydrogen-filled capillary discharge waveguide.

A one-dimensional dissipative magnetohydrodynamics code is used to investigate the discharge dynamics of a waveguide for high-intensity laser pulses: the gas-filled capillary discharge waveguide. Simulations are performed for the conditions of a recent experimental measurement of the electron density profile in hydrogen-filled capillaries [D. J. Spence et al., Phys. Rev. E 63, 015401 (R) (2001)], and are found to be in good agreement with those results. The evolution of the discharge in this device is found to be substantially different to that found in Z-pinch capillary discharges, owing to the fact that the plasma pressure is always much higher than the magnetic pressure. Three stages of the capillary discharge are identified. During the last of these the distribution of plasma inside the capillary is determined by the balance between ohmic heating, and cooling due to electron heat conduction. A simple analytical model of the discharge during the final stage is presented, and shown to be in good agreement with the magnetohydrodynamic simulations.

Journal Article↗