The range of potential applications of compact laser-plasma ion sources motivates the development of new acceleration schemes to increase achievable ion energies and conversion efficiencies. Whilst ...the evolving nature of laser-plasma interactions can limit the effectiveness of individual acceleration mechanisms, it can also enable the development of hybrid schemes, allowing additional degrees of control on the properties of the resulting ion beam. Here we report on an experimental demonstration of efficient proton acceleration to energies exceeding 94 MeV via a hybrid scheme of radiation pressure-sheath acceleration in an ultrathin foil irradiated by a linearly polarised laser pulse. This occurs via a double-peaked electrostatic field structure, which, at an optimum foil thickness, is significantly enhanced by relativistic transparency and an associated jet of super-thermal electrons. The range of parameters over which this hybrid scenario occurs is discussed and implications for ion acceleration driven by next-generation, multi-petawatt laser facilities are explored.
It is shown that electrons with momenta exceeding the "free electron" limit of m(e)ca(0)(2)/2 can be produced when a laser pulse and a longitudinal electric field interact with an electron via a ...non-wake-field mechanism. The mechanism consists of two stages: the reduction of the electron dephasing rate γ - p(x)/m(e)c by an accelerating region of electric field and electron acceleration by the laser via the Lorentz force. This mechanism can, in principle, produce electrons that have longitudinal momenta that is a significant multiple of m(e)ca(0)(2)/2. 2D particle-in-cell simulations of a relatively simple laser-plasma interaction indicate that the generation of superponderomotive electrons is strongly affected by this "antidephasing" mechanism.
The acceleration of ions from ultrathin foils has been investigated by using 250 TW, subpicosecond laser pulses, focused to intensities of up to 3 × 10(20) W cm(-2). The ion spectra show the ...appearance of narrow-band features for protons and carbon ions peaked at higher energies (in the 5-10 MeV/nucleon range) and with significantly higher flux than previously reported. The spectral features and their scaling with laser and target parameters provide evidence of a multispecies scenario of radiation pressure acceleration in the light sail mode, as confirmed by analytical estimates and 2D particle-in-cell simulations. The scaling indicates that monoenergetic peaks with more than 100 MeV/nucleon are obtainable with moderate improvements of the target and laser characteristics, which are within reach of ongoing technical developments.
Familial dysbetalipoproteinemia is associated with the accumulation of remnant lipoproteins and premature cardiovascular disease. Identification of dysbetalipoproteinemia is important because family ...members may be affected. Diagnostic testing involves demonstration of β-lipoprotein in the VLDL fraction or characterization of apo E
. These investigations are complex and relatively expensive. The ratios of apo B to total cholesterol and triglycerides have been proposed as screening tests. However, the ratio of non-HDL cholesterol to apo B (NHDLC/apoB) could offer improved performance as the confounding effect of variations in HDL cholesterol is removed.
We evaluated NHDLC/apoB as a screening test for dysbetalipoproteinemia, using β-quantification analysis as a reference standard. Data from 1637 patients referred over a 16-year period for β quantification were reviewed retrospectively. In 63 patients, diagnostic criteria for dysbetalipoproteinemia (VLDL cholesterol/triglyceride ratio ≥0.69 and presence of β-VLDL) were fulfilled, and 1574 patients had dysbetalipoproteinemia excluded.
Mean NHDLC/apoB in patients with dysbetalipoproteinemia was 7.3 mmol/g (SD, 1.5 mmol/g) and with dysbetalipoproteinemia excluded was 4.0 mmol/g (SD, 0.5 mmol/g). The optimum cutoff of >4.91 mmol/g achieved a diagnostic sensitivity of 96.8% (95% CI, 89.0-99.6) and specificity of 95.0% (95% CI, 93.8-96.0). NHDLC/apoB offered improved performance compared to total cholesterol/apoB diagnostic sensitivity 92.1% (95% CI, 82.4-97.4) and specificity 94.5% (95% CI, 93.2-95.6) with a cutoff of >6.55 mmol/g. NHDL/apoB reference ranges were not sex-dependent, although there was a significant difference between men and women for total cholesterol/apoB.
NHDLC/apoB offers a simple first-line test for dysbetalipoproteinemia in selecting patients with mixed hyperlipidemia for more complex investigations.
Statins are widely used lipid‐lowering drugs that are effective in reducing cardiovascular disease risk. Although they are generally well tolerated, they can cause muscle toxicity, which can lead to ...severe rhabdomyolysis. Research in this area has been hampered to some extent by the lack of standardized nomenclature and phenotypic definitions. We have used numerical and descriptive classifications and developed an algorithm to define statin‐related myotoxicity phenotypes, including myalgia, myopathy, rhabdomyolysis, and necrotizing autoimmune myopathy.
Clinical Pharmacology & Therapeutics (2014); 96 4, 470–476. doi:10.1038/clpt.2014.121
Background
Lipoprotein(a) (Lp(a)) is now established as a causal risk factor for cardiovascular disease (CVD) and accurate laboratory measurement is of pivotal importance in reducing Lp(a) associated ...risk. The consensus statement by HEART UK in 2019 included recommendations to improve standardisation of clinical laboratory measurement and reporting of Lp(a).
Methods
A 16 question, electronic audit survey was circulated to 190 accredited clinical biochemistry laboratories to assess the adoption of these recommendations in the UK.
Results
Responses were received from 65 of 190 laboratories (34%). Only 5 (8%) did not offer Lp(a) measurement. Of those providing the test, 23% (n = 14) offered an in-house service (IHS), the remaining laboratories (77%; n = 46) used an external referral service (ERS). The majority (10 of 14 or 71%) of IHS laboratories responded with details of their method, stating whether it minimised sensitivity to the effect of Lp(a) isoform size and used calibrators certified for traceability to the WHO/IFCC reference material, however, only a minority ERS laboratories (13 of the 46 or 28%) were able to specify the method used by their referral laboratory. Of the laboratories who specified their reporting units, 6 of 10 IHS and 7 of 23 ERS laboratories reported in nmol/L. Among the 60 laboratories who responded, the HEART UK recommendations appear to have been adopted in full by only 3 IHS laboratories.
Conclusions
Further efforts are needed to standardise the measurement and reporting of Lp(a) so that results and interpretation are comparable across clinical biochemistry laboratories in the UK.
Highly anisotropic, beam-like neutron emission with peak flux of the order of 109 n/sr was obtained from light nuclei reactions in a pitcher-catcher scenario, by employing MeV ions driven by a ...sub-petawatt laser. The spatial profile of the neutron beam, fully captured for the first time by employing a CR39 nuclear track detector, shows a FWHM divergence angle of ∼ 70 ° , with a peak flux nearly an order of magnitude higher than the isotropic component elsewhere. The observed beamed flux of neutrons is highly favourable for a wide range of applications, and indeed for further transport and moderation to thermal energies. A systematic study employing various combinations of pitcher-catcher materials indicates the dominant reactions being d(p, n+p)1H and d(d,n)3He. Albeit insufficient cross-section data are available for modelling, the observed anisotropy in the neutrons' spatial and spectral profiles is most likely related to the directionality and high energy of the projectile ions.
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