Observed response of stratospheric and mesospheric composition to sudden stratospheric warmings.

In this study we investigate and quantify the statistical changes that occur in the stratosphere and mesosphere during 37 sudden stratospheric warming (SSW) events from 1989 to 2016. We consider changes in the in-situ ozonesonde observations of the stratosphere from four sites in the northern hemisphere (Ny-Ålesund, Sodankylä, Lerwick, and Boulder). These data are supported by Aura/MLS satellite observations of the ozone volumetric mixing ratio above each site, and also ground-based total-column O3 and NO2, and mesospheric wind measurements, measured at the Sodankylä site. Due to the long-time periods under consideration (weeks/months) we evaluate the observations explicitly in relation to the annual mean of each data set. Following the onset of SSWs we observe an increase in temperature above the mean (for sites usually within the polar vortex) that persists for >∼40 days. During this time the stratospheric and mesospheric ozone (volume mixing ratio and partial pressure) increases by ∼20% as observed by both ozonesonde and satellite instrumentation. Ground-based observations from Sodankylä demonstrate the total column NO2 does not change significantly during SSWs, remaining close to the annual mean. The zonal wind direction in the mesosphere at Sodankylä shows a clear reversal close to SSW onset. Our results have broad implications for understanding the statistical variability of atmospheric changes occurring due to SSWs and provides quantification of such changes for comparison with modelling studies

Highly-parallelized simulation of a pixelated LArTPC on a GPU

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

A História da Alimentação: balizas historiográficas

Os M. pretenderam traçar um quadro da História da Alimentação, não como um novo ramo epistemológico da disciplina, mas como um campo em desenvolvimento de práticas e atividades especializadas, incluindo pesquisa, formação, publicações, associações, encontros acadêmicos, etc. Um breve relato das condições em que tal campo se assentou faz-se preceder de um panorama dos estudos de alimentação e temas correia tos, em geral, segundo cinco abardagens Ia biológica, a econômica, a social, a cultural e a filosófica!, assim como da identificação das contribuições mais relevantes da Antropologia, Arqueologia, Sociologia e Geografia. A fim de comentar a multiforme e volumosa bibliografia histórica, foi ela organizada segundo critérios morfológicos. A seguir, alguns tópicos importantes mereceram tratamento à parte: a fome, o alimento e o domínio religioso, as descobertas européias e a difusão mundial de alimentos, gosto e gastronomia. O artigo se encerra com um rápido balanço crítico da historiografia brasileira sobre o tema

The terrestrial ecology of the natterjack, Bufo calamita(Laurenti), and the common toad, Bufo bufo (Linnaeus)

SIGLEAvailable from British Library Document Supply Centre- DSC:DX176328 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The hydration and alteration of perlite and rhyolite

The volatile concentrations and thermal characteristics of hydrothermally-altered rhyolitic deposits erupted under Icelandic glaciers have been studied by combined differential scanning calorimetry-thermogravimetric analysis-mass spectrometry (DSC-TGA-MS) and x-ray diffraction (XRD). Samples range from pristine obsidians through to strongly-perlitised and altered fragmental deposits. Four types of samples are determined to have notable differences in total volatile concentrations. These are: obsidians (0.44-3.04 wt. %); perlites (2.15-8.15 wt. %); obsidian-breccias (8.49-9.41 wt. %), and hyaloclastites (3.23-7.78 wt. %). DSC-TGA-MS and textural data indicate that the volatile concentration of the perlitic samples increases as the amount of perlitisation increases. XRD data show that the volatile-rich samples are rich in the low-temperature zeolite minerals heulandite and mordenite. The temperature at which volatile exsolution occurs is shown to decrease as the volatile concentration increases reflecting the speciation of water as well as zeolite mineral growth

Trematode (Digenea: Bucephalidae) infection in the burrowing clam Tridacna crocea from the Great Barrier Reef

Larval trematode (Family Bucephalidae) infection of Tridacna crocea (Lamarck 1819) was investigated to determine pathological effects on the host. Of 108 T. crocea gonads examined, 13 (12%) were found to be parasitised. The bucephalid caused castration in heavily infected clams, gonadal tissue being completely replaced by sporocysts. The parasite was also found in the kidney, digestive gland and ctenidia. This is the first record of a bucephalid trematode in a member of the Tridacnidae. The parasite is of potential importance to tridacnid shellfisheries currently being developed

Form-finding as a modelling tool for shaping mechanical components: a feasibility case study of an axial-flow compressor blade

This paper reports on an exploratory study to assess the capability of a novel, form-finding methodology for generating optimal shapes of shell-type structures subjected to complex load regimes, using an axial-flow, compressor blade as a case study. The methodology exploits the natural principle of 'form follows force', in which the structural form is shaped according to the forces acting on it. Such forms, or objects, which are found in nature, are known to have optimal strength and stiffness characteristics for a predominant load regime. Our methodology makes use of a direct relationship between form and force, offered by the Laplace-Young equation that describes shapes of minimal surface membranes, such as soap films. Unlike structural optimisation in which the form is modified within its initially prescribed shape, form-finding literally finds the shape within prescribed boundary conditions. This is the first application of the methodology to modelling mechanical components, such as a compressor blade. The blade shapes obtained by this method correspond, in the first instance, to a minimal form and, subsequently, a minimal form subjected to a known (empirically determined) pressure profile. The behaviour of the blades is studied under a variety of loads and includes modal analysis. In view of the methodology adopted, attention is directed to structural performance. The results, compared against a 'control' blade produced by a conventional design/optimisation method are very encouraging; they indicate that the proposed methodology has the potential to improve significantly the current blade design process