2,958 research outputs found

    Love, Freedom, and Evil: Does Authentic Love Require Free Will?

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    Vroom, H.M. [Promotor]Beek, A. van de [Promotor

    Variational semi-blind sparse deconvolution with orthogonal kernel bases and its application to MRFM

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    We present a variational Bayesian method of joint image reconstruction and point spread function (PSF) estimation when the PSF of the imaging device is only partially known. To solve this semi-blind deconvolution problem, prior distributions are specified for the PSF and the 3D image. Joint image reconstruction and PSF estimation is then performed within a Bayesian framework, using a variational algorithm to estimate the posterior distribution. The image prior distribution imposes an explicit atomic measure that corresponds to image sparsity. Importantly, the proposed Bayesian deconvolution algorithm does not require hand tuning. Simulation results clearly demonstrate that the semi-blind deconvolution algorithm compares favorably with previous Markov chain Monte Carlo (MCMC) version of myopic sparse reconstruction. It significantly outperforms mismatched non-blind algorithms that rely on the assumption of the perfect knowledge of the PSF. The algorithm is illustrated on real data from magnetic resonance force microscopy (MRFM)

    Reptiles sold as traditional medicine in Xipamanine and Xiquelene Markets (Maputo, Mozambique).

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    Zootherapy plays a role in healing practices in Mozambican society. Although several studies have focused on ethnobotany and traditional medicine in the country, little research has been conducted on the use of reptiles in zootherapy. The aim of this study was therefore to fill this gap by assessing the reptile species traded for traditional medicine in the Xipamanine and Xiquelene Markets in Maputo, Mozambique. We found that few reptile species are traded domestically for traditional medicine and that their use appears to be in decline in Mozambique. Our findings also suggest that the domestic trade of reptiles for traditional medicines in Maputo markets is unlikely to have a significant impact on the conservation of reptiles in Mozambique. However, we suggest that international trade with South Africa is likely having a larger impact, given observations of Mozambican nationals selling a diverse range of fauna in urban traditional medicine markets in Johannesburg and Durban.SP201

    Practice pointer: Using the new UK-WHO growth charts

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    The new UK growth charts for children aged 0-4 years (designed using data from the new WHO standards) describe the optimal pattern of growth for all children, rather than the prevailing pattern in the UK (as with previous charts). The new charts are suitable for all ethnic groups and set breast feeding as the norm. UK children match the new charts well for length and height, but after age 6 months fewer children will be below the 2nd centile for weight or show weight faltering, and more will be above the 98th centile. The new charts look different: they have a separate preterm section, no lines between 0 and 2 weeks, and the 50th percentile is no longer emphasised. The charts give clear instructions on gestational correction, and there is a new chart for infants born before 32 weeks’ gestation. The instructions advise on when and how to measure and when a measurement or growth pattern is outside the normal range. The charts include a “look-up” tool for determining the body mass index centile from height and weight centiles without calculation and aid for predicting adult height. The charts and supporting educational materials can be downloaded from www.growthcharts.rcpch.ac.u

    A comparison of braking and differential control of road vehicle yaw-sideslip dynamics

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    Two actuation mechanisms are considered for the comparison of performance capabilities in improving the yaw–sideslip handling characteristics of a road vehicle. Yaw moments are generated either by the use of single-wheel braking or via driveline torque distribution using an overdriven active rear differential. For consistency, a fixed reference vehicle system is used, and the two controllers are synthesized via a single design methodology. Performance measures relate to both open-loop and closed-loop driving demands, and include both on-centre and limit handling manoeuvres

    Topography, substratum and benthic macrofaunal relationships on a tropical mesophotic shelf margin, central Great Barrier Reef, Australia

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    Habitats and ecological communities occurring in the mesophotic region of the central Great Barrier Reef (GBR), Australia, were investigated using autonomous underwater vehicle (AUV) from 51 to 145 m. High-resolution multibeam bathymetry of the outer-shelf at Hydrographers Passage in the central GBR revealed submerged linear reefs with tops at 50, 55, 80, 90, 100 and 130 m separated by flat, sandy inter-reefal areas punctuated by limestone pinnacles. Cluster analysis of AUV images yielded five distinct site groups based on their benthic macrofauna, with rugosity and the presence of limestone reef identified as the most significant abiotic factors explaining the distribution of macrofaunal communities. Reef-associated macrofaunal communities occurred in three distinct depth zones: (1) a shallow (75 m). The effects of depth and microhabitat topography on irradiance most likely play a critical role in controlling vertical zonation on reef substrates. The lower depth limits of zooxanthellate corals are significantly shallower than that observed in many other mesophotic coral ecosystems. This may be a result of resuspension of sediments from the sand sheets by strong currents and/or a consequence of cold water upwelling

    In situ three-dimensional study of corrosion fatigue crack initiation and growth of corroded 7075 aluminum alloys

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    Corrosion fatigue crack initiation in aluminum alloys can have significant effects on part life. An improved understanding of the mechanisms governing corrosion and corrosion fatigue damage of Al alloys is necessary. Alloy design and environmental chemistry have significant effects on corrosion fatigue crack initiation and growth. Influential alloy design features include alloy chemistry, precipitate structure, and grain structure. Environmental factors such as environmental chemistry and preexisting corrosion damage can also effect the corrosion fatigue behavior of the alloys. To investigate the effects of environment and precipitate size on corrosion fatigue of aluminum alloys, the in situ corrosion fatigue testing of corroded peak-aged and overaged 7075 Al alloys in 3.5 wt% NaCl solution will be presented. For this study, rolled 7075 Al alloy was heat-treated to peak-aged, overaged, and highly overaged conditions. The samples were machined, mechanically polished, masked, and then soaked in 3.5 wt.% NaCl solution for fifteen days to yield significant corrosion damage in a region of interest. The corroded specimens were fatigue tested in situ in 3.5 wt.% NaCl using synchrotron X-ray tomography to gain three dimensional information regarding fatigue crack initiation and growth characteristics. Hydrogen bubbles were observed within the crack during propagation, indicating chemical changes in the sample during corrosion fatigue. The crack initiation, growth, and bubble evolution were quantified and discussed. A relationship was observed between the bubble volume and crack surface area as the test progressed, which suggested an effect from stress at the crack tip. Ultimately, this in situ study provided new insights regarding the localized processes occurring during the corrosion fatigue cracking of aluminum alloys which previous post-mortem and two dimensional studies were unable to discover

    An integrated evaluation of potential management processes on marine reserves in continental Ecuador based on a Bayesian belief network model

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    Evaluating potential effects of conservation and management actions in marine reserves requires an understanding not only of the biological processes in the reserve, and between the reserve and the surrounding ocean, but also of the effects of the wildlife on the wider political and economic processes. Such evaluations are made considerably more difficult in the absence of good ecological data from within reserves or consistent data between reserves and the wider marine environment, as is the case in much of mainland Ecuador. We present an approach to evaluate the effects of a wide range of possible management processes on the marine ecology of the Machalilla National Park, as well as that of the surrounding marine environments (including recently established reserves) and related socio-economic pressures. The approach is based on Bayesian belief networks, and as such can be used in the presence of sparse data from multiple and disparate sources. We show that currently there are no observable benefits of marine reserves to reef and fish community structure, and that high value (normally predatory) fish, which are sought by fishers and shark finners are frequently absent from reef systems. We demonstrate that there is broad similarity in ecological communities between most shallow marine systems, in or out of marine reserves, and predict there can be a strong effect from actions outside the reserve on what is present within it. We also show that establishing a stronger link between (responsible) ecotourism and the marine environment could reduce the need for income in other more destructive areas, such as fishing and particularly shark finning, and discuss ways that high value, low impact eco-tourism could be introduced

    Chemical telemetry of OH observed to measure interstellar magnetic fields

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    We present models for the chemistry in gas moving towards the ionization front of an HII region. When it is far from the ionization front, the gas is highly depleted of elements more massive than helium. However, as it approaches the ionization front, ices are destroyed and species formed on the grain surfaces are injected into the gas phase. Photodissociation removes gas phase molecular species as the gas flows towards the ionization front. We identify models for which the OH column densities are comparable to those measured in observations undertaken to study the magnetic fields in star forming regions and give results for the column densities of other species that should be abundant if the observed OH arises through a combination of the liberation of H2O from surfaces and photodissociation. They include CH3OH, H2CO, and H2S. Observations of these other species may help establish the nature of the OH spatial distribution in the clouds, which is important for the interpretation of the magnetic field results.Comment: 11 pages, 2 figures, accepted by Astrophysics and Space Scienc
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