The views of various professions on causes and treatment of learning disabilities - A literature survey and review

The views of various professions on causes and treatment of learning disabilities - A literature survey and revie

Cache-Oblivious Persistence

Partial persistence is a general transformation that takes a data structure and allows queries to be executed on any past state of the structure. The cache-oblivious model is the leading model of a modern multi-level memory hierarchy.We present the first general transformation for making cache-oblivious model data structures partially persistent

Analysis of strategies for improving uranium utilization in pressurized water reactors

Systematic procedures have been devised and applied to evaluate core design and fuel management strategies for improving uranium utilization in Pressurized Water Reactors operated on a once-through fuel cycle. A principal objective has been the evaluation of suggested improvements on a self-consistent basis, allowing for concurrent changes in dependent variables such as core leakage and batch power histories, which might otherwise obscure the sometimes subtle effects of interest. Two levels of evaluation have been devised: a simple but accurate analytic model based on the observed linear variations in assembly reactivity as a function of burnup; and a numerical approach, embodied in a computer program, which relaxes this assumption and combines it with empirical prescriptions for assembly (or batch) power as a function of reactivity, and core leakage as a function of peripheral assembly power. State-of-the-art physics methods, such as PDQ-7, were used to verify and supplement these techniques.These methods have been applied to evaluate several suggested improvements: (1) axial blankets of low-enriched or depleted uranium, and of beryllium metal, (2) radial natural uranium blankets, (3) lowleakage radial fuel management, (4) high burnup fuels, (5) optimized H/U atom ratio, (6) annular fuel, and (7) mechanical spectral shift (i.e. variable fuel-to-moderator ratio) concepts such as those involving pin pulling and bundle reconstitution.The potential savings in uranium requirements compared to current practice were found to be as follows: (1) O0-3%, (2) negative, (3) 2-3%; possibly 5%, (4) "15%, (5) 0-2.5%, (6) no inherent advantage, (7) 10%. Total savings should not be assumed to be additive; and thermal/hydraulic or mechanical design restrictions may preclude full realization of some of the potential improvements

Successional specialization in a reptile community cautions against widespread planned burning and complete fire suppression

Conservation of biodiversity in fire-prone regions depends on understanding responses to fire in animal communities and the mechanisms governing these responses. We collated data from an Australian semi-arid woodland reptile community (4796 individuals captured over 6 years) to: (i) determine the ability of commonly used shorter-term (2 years) surveys to detect reptile responses to time since fire (TSF) and (ii) investigate whether ecological traits of species reliably predicted their responses to fire. Of 16 reptile species analysed, four had responses to TSF consistent with shorter-term surveys and three showed no response to TSF. Nine species had responses to TSF not detected in previous studies using smaller but substantial subsets of the same data. Among the 13 affected species, times of peak abundance ranged from 1 to 50 years after fire. Nocturnal, burrowing species tended to be early successional and leaf-litter dwellers to be late successional, but these were only weak trends. Synthesis and applications. We found only limited support for a generalizable, trait-based model of succession in reptiles. However, our study revealed that the majority of common reptile species in our study region specialize on a post-fire successional stage and may therefore become threatened if homogeneous fire regimes predominate. Our study highlights the importance of interpreting results from time- or sample-limited fire studies of reptiles with the knowledge that many ecological responses may not have been detected. In such cases, an adaptive or precautionary approach to fire management may be necessary.This study was funded by the Australian Research Council, The Australian National University, DENR, Flinders University and the Australia and Pacific Science Foundation

Skeletochronological analysis of age in three ‘fire-specialist’ lizard species

Copyright (2013) the Field Naturalists Society of South Australia. Published version of the paper reproduced here with permission from the publisher.Adverse fire regimes threaten the persistence of animals in many ecosystems. ‘Fire-specialist’ species, which specialise on a particular post-fire successional stage, are likely to be at greatest risk of decline under adverse fire regimes. Life history data on fire-specialists, including longevity, are needed to develop tools to assist fire management for conservation. We used skeletochronology to estimate the age of individuals of three South Australian fire-specialist lizard species: Amphibolurus norrisi (Agamidae), Ctenotus atlas (Scincidae) and Nephrurus stellatus (Gekkonidae). Bone samples were sourced from specimens captured in mallee vegetation predominantly on the Eyre Peninsula, South Australia. Transverse sections of femora were prepared using a standard histological procedure. We counted the minimum and maximum number of lines of arrested growth (LAG) in each sample to provide a conservative and non-conservative estimate of age for each individual. Our results showed that A. norrisi may live for at least five and up to seven years, C. atlas for at least three and up to four years and N. stellatus for at least four and up to seven years. The assumptions that one LAG was deposited per year and that endosteal resorption was minimal must be considered before using these estimates in further research. Our results provide a guide to the potential longevity of the three species which can be used in simulation modelling and genetic studies to improve fire management for animal conservation

Analysis of strategies for improving uranium utilization in pressurized water reactors

Includes bibliographical references (pages 238-241)Systematic procedures have been devised and applied to evaluate core design and fuel management strategies for improving uranium utilization in Pressurized Water Reactors operated on a once-through fuel cycle. A principal objective has been the evaluation of suggested improvements on a self-consistent basis, allowing for concurrent changes in dependent variables such as core leakage and batch power histories, which might otherwise obscure the sometimes subtle effects of interest. Two levels of evaluation have been devised: a simple but accurate analytic model based on the observed linear variations in assembly reactivity as a function of burnup; and a numerical approach, embodied in a computer program, which relaxes this assumption and combines it with empirical prescriptions for assembly (or batch) power as a function of reactivity, and core leakage as a function of peripheral assembly power. State-of-the-art physics methods, such as PDQ-7, were used ! to verify and supplement these techniques.These methods have been applied to evaluate several suggested improvements: (1) axial blankets of low-enriched or depleted uranium, and of beryllium metal, (2) radial natural uranium blankets, (3) low-leakage radial fuel management, (4) high burnup fuels, (5) optimized H/U atom ratio, (6) annular fuel, and (7) mechanical spectral shift (i.e. variable fuel-to-moderator ratio) concepts such as those involving pin pulling and bundle reconstitution.The potential savings in uranium requirements compared to current practice were found to be as follows: (1) O0-3%, (2) negative, (3) 2-3%; possibly 5%, (4) "15%, (5) 0-2.5%, (6) no inherent advantage, (7) 10%. Total savings should not be assumed to be additive; and thermal/hydraulic or mechanical design restrictions may preclude full realization of some of the potential improvements

Studies of two-region subcritical uranium heavy water lattices

"February 1969.""MIT-2344-13."Some technical reports have the series numbering of MITNE-84Substantially the same as J.W. Gosnell's Ph. D. thesis in the Dept. of Nuclear Engineering, 1969Includes bibliographical references (leaves [212]-215)Reactor physics parameters were measured in eleven two-region subcritical assemblies moderated by heavy water. The regions of the assemblies consisted of nine different lattices of various fuel rod size, U235 enrichment, and spacing. The following parameters were measured in the assemblies: bare and cadmium-covered gold foil radial traverses; bare gold foil axial traverses; the ratio of epicadmium to subcadmium capture r tes in U238 (P28); and the ratio of fissions in U238 to fissions in U233(628)- From analysis of axial traverses at various radial positions, it was determined that the axial buckling was independent of radial position in the assemblies. A method was developed to apply the age equation to the experimental gold foil traverses. This analysis yielded the quantity [ ... ] for each region of the assemblies. Calculated values of [ ... ] were used to obtain values of the infinite multiplication factor from this parameter.For assemblies of sufficiently large inner regions, the values of km so found agreed within experimental uncertainty with independent determinations. The slowing-down spectra. arising from the age theory analysis were used to extrapolate two-region assembly measurements of P28 to critical assembly values. General agreement was found between these extrapolated values and the results of measurements made in full, single region lattices. The heterogeneous expressions for uncollided flux derived by Pilat were extended to two-region assemblies and used to determine single rod values of 628 from two-region assembly measurements. The theory was also used to predict values of 628 for each of the lattices composing the two-region assemblies. Both the single rod values and the full lattice predictions agreed within experimental error with previously reported results. The determination of material buckling from two-region subcritical assemblies is also discussed.!Because of the nature of the assemblies investigated, satisfactory measurements of the material buckling could not be made.U.S. Atomic Energy Commission contract AT(30-1)-234

The Optical Design of CHARIS: An Exoplanet IFS for the Subaru Telescope

High-contrast imaging techniques now make possible both imaging and spectroscopy of planets around nearby stars. We present the optical design for the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS), a lenslet-based, cryogenic integral field spectrograph (IFS) for imaging exoplanets on the Subaru telescope. The IFS will provide spectral information for 138x138 spatial elements over a 2.07 arcsec x 2.07 arcsec field of view (FOV). CHARIS will operate in the near infrared (lambda = 1.15 - 2.5 microns) and will feature two spectral resolution modes of R = 18 (low-res mode) and R = 73 (high-res mode). Taking advantage of the Subaru telescope adaptive optics systems and coronagraphs (AO188 and SCExAO), CHARIS will provide sufficient contrast to obtain spectra of young self-luminous Jupiter-mass exoplanets. CHARIS will undergo CDR in October 2013 and is projected to have first light by the end of 2015. We report here on the current optical design of CHARIS and its unique innovations.Comment: 15 page

A temperature‐controlled, circular maintenance system for studying growth and development of pelagic tunicates (salps)

Salps have attracted attention as zooplankton organisms that may be able to expand their habitat range and increase their ecological importance in the face of ongoing global warming. Due to their gelatinous nature, unique feeding strategy, and reproductive ecology such changes could have profound impacts on regional marine ecosystems. While their role in the regional carbon cycle is receiving attention, our knowledge of their physiology and life cycle is still limited. This knowledge gap is mainly due to their fragile gelatinous nature, which makes it difficult to capture and maintain intact specimen in the laboratory. We present here a modified kreisel tank system that has been tested onboard a research vessel with the Southern Ocean salp Salpa thompsoni and at a research station with Salpa fusiformis and Thalia democratica from the Mediterranean Sea. Successful maintenance over days to weeks allowed us to obtain relative growth and developmental rates comparable to in situ field samples of S. thompsoni and S. fusiformis, and provided insights into previously unknown features of their life cycle (e.g., testes development). Our results show that traditional methods of estimating growth, such as cohort analysis, may lead to a general overestimation of growth rates and neglect individual strategies (e.g., shrinkage), which can affect the results and conclusions drawn from population dynamic models. By providing a starting point for the successful maintenance of different species, comparable experiments on the physiology of salps is made possible. This will contribute to refining model parameters and improving the reliability of the predictions