ABSTRACT
Laser-plasma accelerators (LPAs) driven by picosecond-scale, kilojoule-class lasers can generate particle beams and x-ray sources that could be utilized in experiments driven by multi-kilojoule, high-energy-density science (HEDS) drivers such as the OMEGA laser at the Laboratory for Laser Energetics (LLE) or the National Ignition Facility at Lawrence Livermore National Laboratory. This paper reports on the development of the first LPA driven by a short-pulse, kilojoule-class laser (OMEGA EP) connected to a multi-kilojoule HEDS driver (OMEGA). In experiments, electron beams were produced with electron energies greater than 200 MeV, divergences as low as 32 mrad, charge greater than 700 nC, and conversion efficiencies from laser energy to electron energy up to 11%. The electron beam charge scales with both the normalized vector potential and plasma density. These electron beams show promise as a method to generate MeV-class radiography sources and improved-flux broadband x-ray sources at HEDS drivers.
ABSTRACT
Carotid endarterectomy (CEA) within two weeks of the index neurological event (INE) achieves maximum stroke prevention. This study assesses the impact of institution-wide policy changes on CEA performance in symptomatic patients. Between two study periods (1 January 2007 and 31 December 2007; 1 August 2008 and 31 July 2009) transient ischaemic attack (TIA) clinics, an acute stroke protocol and utilisation of vascular operating lists, were adopted. Following the changes, the interval between the INE and CEA fell from 23 (n = 65; interquartile range (IQR) 9-66) to 6.5 (n = 52; IQR 2-13.5) days (p < 0.001) with 32.3% v 82.7% performed within two weeks (p < 0.001). Significant improvements were seen in the time taken from onset of symptoms to presentation, and presentation to a carotid duplex and surgical review. Univariate analyses suggest this improvement is associated with the type of INE, point of presentation and the need for further imaging. Implementation of these policies has produced a significant improvement in service provision largely meeting the two-week target.
Subject(s)
Quality of Health Care/standards , State Medicine/standards , Aged , Aged, 80 and over , Endarterectomy, Carotid , Female , Guidelines as Topic , Humans , Male , Middle Aged , Stroke/prevention & control , United KingdomABSTRACT
Human herpesvirus 8 (HHV-8) is thought to be highly prevalent in Mediterranean countries and sub-Saharan Africa, where it causes Kaposi's sarcoma in a small proportion of infected immunocompetent persons. However, the lack of serological tests with established accuracy has hindered our understanding of the prevalence, risk factors and natural history of HHV-8 infection. We tested 837 subjects from Congo, Botswana (mostly young adults) and Malta (elderly adults), using an immunofluorescence assay and 2 enzyme immunoassays (EIAs, to viral proteins K8.1 and orf65). Each assay found HHV-8 seroprevalence to be high (49-87%) in the African populations and generally lower (9-54%) in Malta. However, there was only modest agreement among tests regarding which subjects were seropositive (3-way kappa, 0.05-0.34). We used latent class analysis to model this lack of agreement, estimating each test's sensitivity and specificity and each population's HHV-8 prevalence. Using this approach, the K8.1 EIA had consistently high sensitivity (91-100%) and specificity (92-100%) across populations, suggesting that it might be useful for epidemiological studies. Compared with the K8.1 EIA, both the immunofluorescence assay and the orf65 EIA had more variable sensitivity (80-100% and 58-87%, respectively) and more variable specificity (57-100% and 48-85%, respectively). HHV-8 prevalence was 7% among elderly Maltese adults. Prevalence was much higher (82%) in Congo, consistent with very high Kaposi's sarcoma incidence there. Prevalence was also high in Botswana (87% in Sans, an indigenous group, and 76% in Bantus), though Kaposi's sarcoma is not common, suggesting that additional co-factors besides HHV-8 are needed for development of Kaposi's sarcoma.
