A Rapidly-Converging Alternative to Source Iteration for Solving the Discrete Ordinates Radiation Transport Equations in Slab Geometry

I present a numerical technique to solve the time independent Boltzmann Transport Equation for the transport of neutrons and photons. The technique efficiently solves the discrete ordinates equations with a new iteration scheme. I call this new scheme the angle space distribution iteration method because it combines a non-linear, high angular-resolution flux approximation within individual spatial cells with a coarse angular-resolution flux approximation that couples all cells in a spatial mesh. This shown to be an efficient alternative to source iteration. The new method is implemented using the step characteristic and exponential characteristic spatial quadrature schemes. The latter was introduced in 1993 and has been shown to accurate for both optically thin and optically thick spatial meshes and to produce strictly positive angular fluxes. The discrete ordinates equations can be solved using the conventional source iteration method. However, it is well known that this method converges prohibitively slowly for optically-thick problems with regions that are dominated by scattering rather than absorption. The new scheme converges rapidly even for such problems. Numerical results show that the new scheme is reliably accurate for the problems intended, and that it is fast and efficient in use of memory. The angle space distribution iteration method is demonstrated in slab geometry, for a single energy group, using isotropic cross sections, with exponential and step characteristic spatial quadrature

Fishes of the Lake Eyre catchment of central Australia

Despite a defining quality of a desert being a lack of water, deserts do have water resources which maintain wildlife, especially aquatic wildlife, much of which cannot survive without permanent water. Around 70% of the land mass of Australia is considered arid and the arid areas can be separated broadly into two regions based on its fishes. The western portion includes the inland drainages from west of the Finke River near Alice Springs in the Northern Territory to the edge of the Pilbara in Western Australia. This massive area is largely unexplored for fishes partly because of its remoteness and very scant water resources. The eastern portion, now renamed the Lake Eyre Region, extends from the Finke River east to the Bulloo River at Quilpie and from Mount Isa in Queensland in the north to Broken Hill in New South Wales in the south. This region contains a fascinating assemblage of aquatic animals in a variety of habitats, including a characteristic grouping of fish (33 native species) and the fish communities are in remarkably good condition. The aquatic habitats and the aquatic flora and fauna are described and the management of fishes, wetlands and catchments is discussed. Description, habitat, biology and distribution details are provided for 13 families of fish of the Lake Eyre Region, together small colour photographs

Student attitudes regarding the educational value and welfare implications in the use of model eyes and live dogs in teaching practical fundus examination: evaluation of responses from 40 students

This study sought to document student opinions on the educational value and welfare implications of use of artificial model eyes and live dogs in the training of veterinary students in examination of the canine fundus. Forty students who had undertaken a practical class on canine fundoscopy involving both use of artificial model eyes and live dogs were asked to complete a short questionnaire using a Likert scale to gauge their opinion on whether the use of live dogs and artificial eyes was very valuable (scoring 2), valuable (1), a neutral response (0), not particularly valuable (-1) or not at all valuable (-2) and to write a free text response on their views of the educational value and welfare implications of using artificial model eyes or live dogs in training for ophthalmic examination of the canine ocular fundus. Likert responses were 1.84±0.37 for using live greyhounds and 0.58±0.79 for using simulator eyes (p<0.0001). Thematic analysis of the written responses showed that while the artificial eyes were considered somewhat valuable in initial training, the live dogs were significantly preferred for their realism and the opportunity to examine the eye while handling a live animal. In conclusion, while model eyes are valuable initial training in use of the ophthalmoscope for funduscopic examination, students consider that examining the eye in the live dog is significantly more valuable and that the welfare of dogs thus used is not in their view unduly compromised

Battery cell balance of electric vehicles under fast-DC charging

Electric vehicle (EV) range, recharge opportunities and time to recharge are major barriers to mainstream acceptance. Fast-DC charging has the potential to overcome these barriers. This research investigates the impact of fast-DC charging on battery cell balance, charge capacity and range for an EV travelling long distances on an 'electric-highway'. Two commercially available EVs were exposed to a series of discharge and fast-DC charge cycles to measure cell balance and charge capacity. The vehicles' battery management systems (BMS) were capable of successfully balancing individual cells and hence maintaining the batteries' charge capacity. Although fast-DC charge levels and discharge safety margins significantly reduced the vehicles' charge capacity and range as stated by the manufacturer, these values remained stable for the test period. In regards to cell balance and charge capacity, our research suggests that fast-DC charging technology is a feasible option for EVs to travel large distances in a day

Multivariate brain prediction of heart rate and skin conductance responses to social threat

Psychosocial stressors induce autonomic nervous system (ANS) responses in multiple body systems that are linked to health risks. Much work has focused on the common effects of stress, but ANS responses in different body systems are dissociable and may result from distinct patterns of cortical–subcortical interactions. Here, we used machine learning to develop multivariate patterns of fMRI activity predictive of heart rate (HR) and skin conductance level (SCL) responses during social threat in humans (N = 18). Overall, brain patterns predicted both HR and SCL in cross-validated analyses successfully (r(HR) = 0.54, r(SCL) = 0.58, both p < 0.0001). These patterns partly reflected central stress mechanisms common to both responses because each pattern predicted the other signal to some degree (r(HR→SCL) = 0.21 and r(SCL→HR) = 0.22, both p < 0.01), but they were largely physiological response specific. Both patterns included positive predictive weights in dorsal anterior cingulate and cerebellum and negative weights in ventromedial PFC and local pattern similarity analyses within these regions suggested that they encode common central stress mechanisms. However, the predictive maps and searchlight analysis suggested that the patterns predictive of HR and SCL were substantially different across most of the brain, including significant differences in ventromedial PFC, insula, lateral PFC, pre-SMA, and dmPFC. Overall, the results indicate that specific patterns of cerebral activity track threat-induced autonomic responses in specific body systems. Physiological measures of threat are not interchangeable, but rather reflect specific interactions among brain systems. SIGNIFICANCE STATEMENT We show that threat-induced increases in heart rate and skin conductance share some common representations in the brain, located mainly in the vmPFC, temporal and parahippocampal cortices, thalamus, and brainstem. However, despite these similarities, the brain patterns that predict these two autonomic responses are largely distinct. This evidence for largely output-measure-specific regulation of autonomic responses argues against a common system hypothesis and provides evidence that different autonomic measures reflect distinct, measurable patterns of cortical–subcortical interactions

Rim Pathway-Mediated Alterations in the Fungal Cell Wall Influence Immune Recognition and Inflammation

ACKNOWLEDGMENTS We acknowledge Jennifer Lodge, Woei Lam, and Rajendra Upadhya for developing and sharing the chitin and chitosan MTBH assay. We thank Todd Brennan of Duke University for providing MyD88-deficient mice. We acknowledge Neil Gow for providing access to the Dionex HPAEC-PAD instrumentation. We also acknowledge Connie Nichols for critical reading of the manuscript. These experiments were supported by an NIH grant to J.A.A. and F.L.W., Jr. (R01 AI074677). C.M.L.W. was supported by a fellowship provided through the Army Research Office of the Department of Defense (no. W911NF-11-1-0136 f) (F.L.W., Jr.). J.W., L.W., and C.M. were supported by the Wellcome Trust Strategic Award in Medical Mycology and Fungal Immunology (097377) and the MRC, Centre for Medical Mycology (MR/N006364/1). FUNDING INFORMATION MRC Centre for Medical MycologyMR/N006364/1 Carol A. Munro HHS | NIH | National Institute of Allergy and Infectious Diseases (NIAID) https://doi.org/10.13039/100000060R01 AI074677J. Andrew Alspaugh Wellcome https://doi.org/10.13039/100010269097377 Carol A. Munro DOD | United States Army | RDECOM | Army Research Office (ARO) https://doi.org/10.13039/100000183W911NF-11-1-0136 f Chrissy M. Leopold WagerPeer reviewedPublisher PD

Taylor dispersion of gyrotactic swimming micro-organisms in a linear flow

The theory of generalized Taylor dispersion for suspensions of Brownian particles is developed to study the dispersion of gyrotactic swimming micro-organisms in a linear shear flow. Such creatures are bottom-heavy and experience a gravitational torque which acts to right them when they are tipped away from the vertical. They also suffer a net viscous torque in the presence of a local vorticity field. The orientation of the cells is intrinsically random but the balance of the two torques results in a bias toward a preferred swimming direction. The micro-organisms are sufficiently large that Brownian motion is negligible but their random swimming across streamlines results in a mean velocity together with diffusion. As an example, we consider the case of vertical shear flow and calculate the diffusion coefficients for a suspension of the alga &lt;i&gt;Chlamydomonas nivalis&lt;/i&gt;. This rational derivation is compared with earlier approximations for the diffusivity

Handling manuscript rejection: Insights from evidence and experience

The purpose of this article is to provide authors with insights gained from evidence and experience on how to handle rejected manuscripts

Interdiffusion: A probe of vacancy diffusion in III-V materials

Copyright 1997 by the American Physical Society. Article is available at

The purpose of peer review in the case of an open-access publication

First scientific journals were simply a way of informing colleagues about new research findings. In due course, they started filtering out unreasonable claims, and introduced a peer-review system. The purpose of peer reviewing changed with time. Since the middle of the past century, commercial publishers have owned a large number of scientific journals and as a result, the marketable value of a submitted manuscript has become an increasingly important factor in publishing decisions. Recently some publishers have developed business schemes which may stop this tendency. In the case of an open-access publication, the marketable value of a manuscript is not the primary consideration, since access to the research is not being sold. This innovation challenges scientists to re-consider the purpose of peer review. This editorial indicates some of the commonly used criteria for publication that consequently should receive less or little emphasis under the open-access model