The influence of candidates' physical attributes on assessors' ratings in clinical practice.

BACKGROUND: Assessments of physician competence in the work-place are common and often contribute to high-stakes assessments. Previous research suggests that assessors' judgements can be influenced by candidates' physical attributes. We investigated whether simulated candidates' scores were influenced by assessor bias based on tattoos, hair colour, and a regional accent. METHODS: We used an experimental, video-based, single-blinded, randomised, internet-based design. We created videos of simulated medical intern performances of a clinical examination at four different standards of competence. Four videos were also created of simulated candidates performing at a 'clear pass' standard, with either no stereotypical attribute (CPX), purple hair (CPH), tattoos (CPT) or a Liverpool English accent (CPA). Assessors were randomly assigned to watch five videos including the "clear pass" candidate without an attribute and one of the "clear pass" candidates with an attribute and asked to give an overall global grade for each candidate. We compared the global grades for the clear pass candidates with and without attributes. RESULTS: Ninety-eight assessors were included in the analysis. The total scores for the candidates with stereotyped attributes were not significantly lower than the candidate with no attribute. Assessors showed moderate levels of agreement between the global grades awarded for all the candidates. The global grades awarded to candidate with a stereotypical attribute were not significantly lower than for those without. CONCLUSIONS: The presence of tattoos, purple hair, or a regional accent did not systematically negatively influence the grade or score awarded by assessors to candidates in observed clinical examination scenarios.

A vaccine based on recombinant modified Vaccinia Ankara containing the nucleoprotein from Lassa virus protects against disease progression in a guinea pig model.

Lassa fever remains the most imported viral haemorrhagic fever in Europe and is responsible for 5000 deaths per year throughout Western Africa. There is no vaccine and treatment is often ineffective. We have developed a vaccine based on modified Vaccinia Ankara expressing the nucleoprotein from Lassa virus (MVALassaNP). This study investigated the immunogenicity (in mice) and efficacy (in guinea pigs) of the MVALassaNP vaccine as a prime/boost or single vaccination regime. ELISA and ELISpot assays confirmed humoral and T-cell immunity following both a prime and prime/boost vaccination, with the prime/boost regime producing a statistically increased response compared to a prime only vaccine (P < 0.0001). The vaccine offered protection in guinea pigs against disease manifestations after challenge with virulent Lassa virus. Clinical signs, weight loss and temperature increases were observed in all animals receiving a control MVA vaccine, after challenge with Lassa virus. In contrast, no clinical signs, fever or weight loss were observed in any of the MVALassaNP vaccinated animals demonstrating that both a single immunisation, and prime/boost regime confer protection against disease progression. In conclusion, the MVALassaNP vaccine candidate elicits an immune response, demonstrates efficacy against Lassa virus disease and is suitable for further preclinical and clinical development.

Use of technetium-HMPAO to demonstrate changes in cerebral blood flow reserve following carotid endarterectomy.

Cerebral perfusion through stenosed internal carotid arteries is usually maintained by autoregulation. However, flow reserve may be reduced, suggesting hemodynamically significant stenosis, and such reduction should be improved by carotid endarterectomy. This concept was studied in 20 subjects with unilateral internal carotid artery stenosis (major stenosis greater than or equal to 70%, minor stenosis less than or equal to 50%). Thirteen had experienced recent transient ischemic attacks and seven had no definite focal symptoms. Subjects underwent Tc-HMPAO cerebral SPECT during acetazolamide dysautoregulation before and after internal carotid endarterectomy. Nine (45%) had perfusion defects that improved after surgery, suggesting surgery had improved cerebral flow reserve. Seven had defects that did not improve after surgery. Four had worsened or new defects after surgery, suggesting perioperative infarcts. The relatively large proportion of patients with improved cerebral blood flow reserve after surgery suggests that this technique may have a significant role to play in assessing which patients might benefit from carotid endarterectomy.

The acute response of indium-111 labelled platelets to arteriotomy closure.

A standard 40 mm arteriotomy was created in canine iliac and carotid arteries and then closed by either direct suture without a patch, with a vein patch or with a polytetrafluoroethylene patch (PTFE). The uptake of 111-Indium oxine labelled platelets at 2 hours after operation was compared between the groups. Arteriotomies closed with a PTFE patch demonstrated significantly greater platelet aggregation than those closed with a vein patch. Primary closure without a patch was associated with the least platelet uptake of all (PTFE versus vein patch, P less than 0.01; PTFE versus no patch, P less than 0.01; vein patch versus no patch, P less than 0.05). Light and electron microscopy confirmed the radioisotopic findings.

Cerebral perfusion defects, dysautoregulation and carotid stenosis.

Single Photon Emission Computed Tomography (SPECT), imaging of cerebral blood flow was carried out in ten patients with haemodynamically significant carotid stenosis. Before and after carotid endarterectomy each patient was investigated by 3--dimensional SPECT brain scanning using technetium--hexamethyl propyleneamine oxine (99 mTcHMPAO, ceretec). Brain blood flow was normal before and after operation in 3 patients whose autoregulation was kept intact. Seven patients received acetazolamide to limit cerebral vascular reactivity and in four of these, preoperative perfusion defects were visible. After carotid endarterectomy the ipsilateral perfusion defects were abolished and it is concluded that carotid stenosis can reduce perfusion in the dysautoregulation brain and that carotid reconstruction can restore normal flow.

The DCU laser ion source.

Laser ion sources are used to generate and deliver highly charged ions of various masses and energies. We present details on the design and basic parameters of the DCU laser ion source (LIS). The theoretical aspects of a high voltage (HV) linear LIS are presented and the main issues surrounding laser-plasma formation, ion extraction and modeling of beam transport in relation to the operation of a LIS are detailed. A range of laser power densities (I approximately 10(8)-10(11) W cm(-2)) and fluences (F=0.1-3.9 kJ cm(-2)) from a Q-switched ruby laser (full-width half-maximum pulse duration approximately 35 ns, lambda=694 nm) were used to generate a copper plasma. In "basic operating mode," laser generated plasma ions are electrostatically accelerated using a dc HV bias (5-18 kV). A traditional einzel electrostatic lens system is utilized to transport and collimate the extracted ion beam for detection via a Faraday cup. Peak currents of up to I approximately 600 microA for Cu(+) to Cu(3+) ions were recorded. The maximum collected charge reached 94 pC (Cu(2+)). Hydrodynamic simulations and ion probe diagnostics were used to study the plasma plume within the extraction gap. The system measured performance and electrodynamic simulations indicated that the use of a short field-free (L=48 mm) region results in rapid expansion of the injected ion beam in the drift tube. This severely limits the efficiency of the electrostatic lens system and consequently the sources performance. Simulations of ion beam dynamics in a "continuous einzel array" were performed and experimentally verified to counter the strong space-charge force present in the ion beam which results from plasma extraction close to the target surface. Ion beam acceleration and injection thus occur at "high pressure." In "enhanced operating mode," peak currents of 3.26 mA (Cu(2+)) were recorded. The collected currents of more highly charged ions (Cu(4+)-Cu(6+)) increased considerably in this mode of operation.

Spectroscopic characterization of vacuum ultraviolet free electron laser pulses.

Because of the stochastic nature of self-amplified spontaneous emission (SASE), it is crucial to measure for single pulses the spectral characteristics of ultrashort pulses from the vacuum ultraviolet free electron laser (FLASH) at DESY, Germany. To meet this particular challenge, we have employed both photon and photoelectron spectroscopy. Each FEL pulse is composed of an intense and spectrally complex fundamental, centered at a photon energy of about 38.5 eV, with a bandwidth of 0.5% accompanied by higher harmonics, each carrying an intensity of typically 0.3 to 0.6% of that of the fundamental. The correlation between the harmonics and the fundamental is in remarkable agreement with a simple statistical model of SASE FEL radiation.

Effectiveness of delayed activated charcoal administration in simulated paracetamol (acetaminophen) overdose.

AIMS: Oral activated charcoal is used to treat drug overdose and is effective at reducing drug absorption when administered within 1 h of drug ingestion. There are fewer data on efficacy when the delay is longer, as is the case in most drug overdoses. This study investigated the efficacy of activated charcoal at preventing paracetamol (acetaminophen) absorption after simulated overdose when administration was delayed between 1 and 4 h. METHODS: An open randomized-order four-way crossover study was performed in healthy volunteers comparing the effect of activated charcoal 50 g on the absorption of 3 g paracetamol tablets when administered after an interval of 1, 2 or 4 h or not at all. Plasma paracetamol concentrations were measured over 9 h after paracetamol ingestion using h.p.l.c. and areas under the curve between 4 and 9 h (AUC(4,9 h)) calculated as a measure of paracetamol absorption. RESULTS: Activated charcoal significantly reduced paracetamol AUC(4,9 h) when administered after 1 h (mean reduction 56%; 95% Confidence intervals 34, 78; P<0.002) or 2 h (22%; 6, 39; P<0.03) but not after 4 h (8%; -8, 24). When administered after 1 h activated charcoal reduced individual plasma paracetamol concentrations significantly at all times between 4 and 9 h after paracetamol administration. Administration at 2 or 4 h had no significant effect. CONCLUSIONS: These results in healthy volunteers cannot be extrapolated directly to poisoned patients. However, they provide no evidence of efficacy for activated charcoal when administered after an interval of more than 2 h.