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In the 2015 review paper ‘Petawatt Class Lasers Worldwide’ a comprehensive overview of the current status of high-power facilities of
was presented. This was largely based on facility specifications, with some description of their uses, for instance in fundamental ultra-high-intensity interactions, secondary source generation, and inertial confinement fusion (ICF). With the 2018 Nobel Prize in Physics being awarded to Professors Donna Strickland and Gerard Mourou for the development of the technique of chirped pulse amplification (CPA), which made these lasers possible, we celebrate by providing a comprehensive update of the current status of ultra-high-power lasers and demonstrate how the technology has developed. We are now in the era of multi-petawatt facilities coming online, with 100 PW lasers being proposed and even under construction. In addition to this there is a pull towards development of industrial and multi-disciplinary applications, which demands much higher repetition rates, delivering high-average powers with higher efficiencies and the use of alternative wavelengths: mid-IR facilities. So apart from a comprehensive update of the current global status, we want to look at what technologies are to be deployed to get to these new regimes, and some of the critical issues facing their development.
As part of further investigations into three linked haemorrhagic fever with renal syndrome (HFRS) cases in Wales and England, 21 rats from a breeding colony in Cherwell, and three rats from a household in Cheltenham were screened for hantavirus. Hantavirus RNA was detected in either the lungs and/or kidney of 17/21 (81%) of the Cherwell rats tested, higher than previously detected by blood testing alone (7/21, 33%), and in the kidneys of all three Cheltenham rats. The partial L gene sequences obtained from 10 of the Cherwell rats and the three Cheltenham rats were identical to each other and the previously reported UK Cherwell strain. Seoul hantavirus (SEOV) RNA was detected in the heart, kidney, lung, salivary gland and spleen (but not in the liver) of an individual rat from the Cherwell colony suspected of being the source of SEOV. Serum from 20/20 of the Cherwell rats and two associated HFRS cases had high levels of SEOV-specific antibodies (by virus neutralisation). The high prevalence of SEOV in both sites and the moderately severe disease in the pet rat owners suggest that SEOV in pet rats poses a greater public health risk than previously considered.
A commonly accepted distinction between snow-patches and glaciers is the slow mass movement of the latter with consequent abrasion of stones and rock surfaces. However, the observations of some workers do not support this distinction. The present study, in a snow-patch area on Mount Twynam in the Snowy Mountains (Australia), presents positive evidence of slow mass sliding of snow, causing transport, abrasion and detachment of stones and abrasion of the bedrock surface. Consequently, no sharp separation is possible between the erosional effects of snow-patches and small cirque glaciers. In areas such as the Snowy Mountains the relative importance of glacial and nivational processes becomes more difficult to evaluate.
The morphology of Snaefell, East Iceland, and the state of its glaciers in 1937 are described. There are four small glaciers. Two of these exist in well-developed cirques incised into the lavas, tuffs and breccias of this Pleistocene volcano. The third receives ice from a summit ice cap, while the fourth also receives ice from the same source as well as lying in a cirque. The firn line in 1937 is put between 1350 and 1500 m. so that the mass balance of the glaciers is unlikely to have been favourable, although only one showed any abandoned moraines. An explanation of the varying glacial modification of the different slopes of Snaefell is suggested in terms of structural trends, shading from the sun and snow-drifting.
A. N. Lewis’s scheme of Tasmania’s Pleistocene glacial history in terms of three full glaciations —Malanna (ice cap), Yolande (valley glacier) and Margaret (cirque glacier)—is criticized on a number of specific and general grounds. The area reliably known to be glaciated is thought to be much smaller than Lewis claimed. Future work on Tasmanian glaciations should not be grafted on to Lewis’s scheme and should aim especially to provide more reliable evidence for distinguishing and evaluating the glacial phases.
Notoedric mange, caused by obligately parasitic sarcoptiform Notoedres mites, is associated with potentially fatal dermatitis with secondary systemic disease in small mammals, felids and procyonids among others, as well as an occasional zoonosis. We describe clinical spectra in non-chiropteran hosts, review risk factors and summarize ecological and epidemiological studies. The genus is disproportionately represented on rodents. Disease in felids and procyonids ranges from very mild to death. Knowledge of the geographical distribution of the mites is highly inadequate, with focal hot spots known for Notoedres cati in domestic cats and bobcats. Predisposing genetic and immunological factors are not known, except that co-infection with other parasites and anticoagulant rodenticide toxicoses may contribute to severe disease. Treatment of individual animals is typically successful with macrocytic lactones such as selamectin, but herd or wildlife population treatment has not been undertaken. Transmission requires close contact and typically is within a host species. Notoedric mange can kill half all individuals in a population and regulate host population below non-diseased density for decades, consistent with frequency-dependent transmission or spillover from other hosts. Epidemics are increasingly identified in various hosts, suggesting global change in suitable environmental conditions or increased reporting bias.
The Central Molecular Zone (CMZ), usually referring to the inner 500 pc of the Galaxy, contains a dozen of massive (~105M⊙) molecular clouds. Are these clouds going to actively form stars like Sgr B2? How are they affected by the extreme physical conditions in the CMZ, such as strong turbulence? Here we present a first step towards answering these questions. Using high-sensitivity, high angular resolution radio and (sub)millimeter observations, we studied deeply embedded star formation in six massive clouds in the CMZ, including the 20 and 50 km s−1 clouds, Sgr B1 off (as known as dust ridge clouds e/f), Sgr C, Sgr D, and G0.253 – 0.016. The VLA water maser observations suggest a population of deeply embedded protostellar candidates, many of which are new detections. The SMA 1.3 mm continuum observations reveal peaks in dust emission associated with the masers, suggesting the existence of dense cores. While our findings confirm that clouds such as G0.253 – 0.016 lack internal compact substructures and are quiescent in terms of star formation, two clouds (the 20 km s−1 cloud and Sgr C) stand out with clusters of water masers with associated dense cores which may suggest a population of deeply embedded protostars at early evolutionary phases. Follow-up observations with VLA and ALMA are necessary to confirm their protostellar nature.
Parasite burden varies widely between individuals within a population, and can covary with multiple aspects of individual phenotype. Here we investigate the sources of variation in faecal strongyle eggs counts, and its association with body weight and a suite of haematological measures, in a cohort of indigenous zebu calves in Western Kenya, using relatedness matrices reconstructed from single nucleotide polymorphism (SNP) genotypes. Strongyle egg count was heritable (h2 = 23·9%, s.e. = 11·8%) and we also found heritability of white blood cell counts (WBC) (h2 = 27·6%, s.e. = 10·6%). All the traits investigated showed negative phenotypic covariances with strongyle egg count throughout the first year: high worm counts were associated with low values of WBC, red blood cell count, total serum protein and absolute eosinophil count. Furthermore, calf body weight at 1 week old was a significant predictor of strongyle EPG at 16–51 weeks, with smaller calves having a higher strongyle egg count later in life. Our results indicate a genetic basis to strongyle EPG in this population, and also reveal consistently strong negative associations between strongyle infection and other important aspects of the multivariate phenotype.
Homogenous blends of a processable methanofullerene, [6,6]-Phenyl C61 - butyric acid methyl ester (PCBM), with poly (p-phenylene vinylene) (PPV) made from a novel nonionic precursor route were investigated by optical spectroscopy and by photocurrent measurements. The conversion process of the precursor polymer to the PPV in the blends with PCBM was monitored by IR absorption. In composites of PPV/PCBM strong quenching of the PPV luminescence was observed. LESR (light induced electron spin resonance) and PIA (photoinduced absorption) studies confirmed the occurrence of photoinduced electron transfer from the PPV to PCBM. Photovoltaic devices made from PPV/PCBM blends showed monochromatic power conversion efficiencies of app. 0.3%. The spectral photocurrent was observed to follow the absorption profile of the PPV.
We have studied the effect of a magnetic field on the photocurrent of MDMO-PPV (poly(2-methoxy,5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene) and MDMOPPV/fullerene diodes (plastic solar cells) and performed photocurrent detected magnetic resonance (PCDMR) experiments on these devices consisting of an active layer sandwiched between a low and a high workfunction metal electrode. Results clearly show that the magnetic field effect (MFE) on the photocuttent as well as PCDMR signals are quenched in conjugated polymer/fullerene composite devices in contrast to large signals observed in the pristine conjugated polymer devices. Photoinduced electron transfer from conjugated polymers onto fullerene is proposed to be responsible for this quenching.
The photo-induced charge transfer between tetracyano-anthraquino-dimethane (TCAQ) derivatives and poly(2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylene vinylene) MDMO-PPV was studied by means of photoinduced absorption (PIA) spectroscopy in the VIS and IR spectral region and lightinduced electron spin resonance (LESR) spectroscopy. Three different TCAQ derivatives with alkyl-side chains for increased solubility compared to TCAQ and one of them attached to a C60 molecule serve as strong electron acceptors. The photoinduced absorption in the VIS near-IR range shows a broad plateau around 1.8 eV followed by two peaks at 1.35 and 1.24eV for all three acceptors. All PIA features have a power law excitation intensity dependence with an exponent close to 0.5 as expected for bimolecular kinetics. The modulation frequency dependent excited state absorption decreases with a power law. LESR studies of all donor-acceptor combinations show one radical line at a g = 2.0028 with.H = 3.5 Gauss, originating from TCAQ anion and the polymer cation.
Regioregular polythiophenes baring 3-(p-methoxyethoxyethoxy)-phenyl substituents (PEOPT) show high photoluminescence efficiencies. Exposing thin films of this polymer to vapors of chloroform or annealing them by heat treatment results in a red shift of the absorption maximum due to solvent or heat induced ordering which gives rise to more planar conformations. The fact, that annealed thin films of PEOPT exhibit absorption edges at relatively low energies and thus have an enhanced spectral range makes them suitable for use in photodiodes / solar cells. The photoinduced charge generation efficiency in PEOPT is significantly enhanced by the addition of a strong electron acceptor like fullerene, as observed by quenching of the luminescence and by photoinduced absorption measurements in the infrared and UV-Vis regime. The efficiency of the photoinduced charge transfer from PEOPT to a methanofullerene is found to depend on the ordering of PEOPT in thin films.