5,934 research outputs found

    Phylogeography and dispersal in the velvet gecko (Oedura lesueurii), and potential implications for conservation of an endangered snake (Hoplocephalus bungaroides).

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    ABSTRACT: BACKGROUND: To conserve critically endangered predators, we also need to conserve the prey species upon which they depend. Velvet geckos (Oedura lesueurii) are a primary prey for the endangered broad-headed snake (Hoplocephalus bungaroides), which is restricted to sandstone habitats in southeastern Australia. We sequenced the ND2 gene from 179 velvet geckos, to clarify the lizards' phylogeographic history and landscape genetics. We also analysed 260 records from a longterm (3-year) capture-mark-recapture program at three sites, to evaluate dispersal rates of geckos as a function of locality, sex and body size. RESULTS: The genetic analyses revealed three ancient lineages in the north, south and centre of the species' current range. Estimates of gene flow suggest low dispersal rates, constrained by the availability of contiguous rocky habitat. Mark-recapture records confirm that these lizards are highly sedentary, with most animals moving < 30 m from their original capture site even over multi-year periods. CONCLUSION: The low vagility of these lizards suggests that they will be slow to colonise vacant habitat patches; and hence, efforts to restore degraded habitats for broad-headed snakes may need to include translocation of lizards

    Prevalence and co-infection of Toxoplasma gondii and Neospora caninum in Apodemus sylvaticus in an area relatively free of cats

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    The protozoan parasite Toxoplasma gondii is prevalent worldwide and can infect a remarkably wide range of hosts despite felids being the only definitive host. As cats play a major role in transmission to secondary mammalian hosts, the interaction between cats and these hosts should be a major factor determining final prevalence in the secondary host. This study investigates the prevalence of T. gondii in a natural population of Apodemus sylvaticus collected from an area with low cat density (<2·5 cats/km2). A surprisingly high prevalence of 40·78% (95% CI: 34·07%–47·79%) was observed despite this. A comparable level of prevalence was observed in a previously published study using the same approaches where a prevalence of 59% (95% CI: 50·13%–67·87%) was observed in a natural population of Mus domesticus from an area with high cat density (>500 cats/km2). Detection of infected foetuses frompregnant dams in both populations suggests that congenital transmission may enable persistence of infection in the absence of cats. The prevalences of the related parasite, Neospora caninum were found to be low in both populations (A. sylvaticus: 3·39% (95% CI: 0·12%–6·66%); M. domesticus: 3·08% (95% CI: 0·11%–6·05%)). These results suggest that cat density may have a lower than expected effect on final prevalence in these ecosystems

    Inverse problem of photoelastic fringe mapping using neural networks

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    This paper presents an enhanced technique for inverse analysis of photoelastic fringes using neural networks to determine the applied load. The technique may be useful in whole-field analysis of photoelastic images obtained due to external loading, which may find application in a variety of specialized areas including robotics and biomedical engineering. The presented technique is easy to implement, does not require much computation and can cope well within slight experimental variations. The technique requires image acquisition, filtering and data extraction, which is then fed to the neural network to provide load as output. This technique can be efficiently implemented for determining the applied load in applications where repeated loading is one of the main considerations. The results presented in this paper demonstrate the novelty of this technique to solve the inverse problem from direct image data. It has been shown that the presented technique offers better result for the inverse photoelastic problems than previously published works

    Evidence for high levels of vertical transmission in Toxoplasma gondii

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    Toxoplasma gondii is a highly ubiquitous and prevalent parasite. Despite the cat being the only definitive host, it is found in almost all geographical areas and warm blooded animals. Three routes of transmission are recognised: ingestion of oocysts shed by the cat, carnivory and congenital transmission. In natural populations, it is difficult to establish the relative importance of these routes. This paper reviews recent work in our laboratory which suggests that congenital transmission may be much more important than previously thought. Using PCR detection of the parasite, studies in sheep show that congenital transmission may occur in as many as 66% of pregnancies. Furthermore, in families of sheep on the same farm, exposed to the same sources of oocysts, significant divergent prevalences of Toxoplasma infection and abortion are found between different families. The data suggest that breeding from infected ewes increases the risk of subsequent abortion and infection in lambs. Congenital transmission rates in a natural population of mice were found to be 75%. Interestingly, congenital transmission rates in humans were measured at 19.8%. The results presented in these studies differ from those of other published studies and suggest that vertical transmission may be much more important than previously thought

    Design and development of a 20 kW cleaning and cooling system for a wood-chip gasifier

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    The present study was undertaken with the objectives to develop a filter system for a 20 kW engine application and to test the filter. It was observed that tar content in the gas ranged from 12.4 to 85 mg/m3 , which was considered on the higher side, in some cases, compared from an accepted limit of 50 mg/m3 . The 20 kW cleaning and cooling system for cleaning of producer gas was developed by calculating the gas flow and maximum retention time in the filter. The diameter of these three filters, viz., water scrubber, wet filter and dry filter was calculated from retention time and velocity in the filter, which was found to be 0.20, 0.40 and 0.50 m respectively, with filter height of 0.80 m. The developed filter was evaluated for reduction of tar in the producer gas after cleaning. The tar content in the producer gas after filtration by using the system varies from 24 to 53.52 mg/m3 . The tar absorption using this filter system was 99.35%, while the pressure drop varied between 10 to 25 mm of the water column. The system was also operated by coupling with a small capacity IC engine. The diesel replacement was found to be in the range of 65.66 %

    Design and development of a 20 kW cleaning and cooling system for a wood-chip gasifier

    Get PDF
    The present study was undertaken with the objectives to develop a filter system for a 20 kW engine application and to test the filter. It was observed that tar content in the gas ranged from 12.4 to 85 mg/m3 , which was considered on the higher side, in some cases, compared from an accepted limit of 50 mg/m3 . The 20 kW cleaning and cooling system for cleaning of producer gas was developed by calculating the gas flow and maximum retention time in the filter. The diameter of these three filters, viz., water scrubber, wet filter and dry filter was calculated from retention time and velocity in the filter, which was found to be 0.20, 0.40 and 0.50 m respectively, with filter height of 0.80 m. The developed filter was evaluated for reduction of tar in the producer gas after cleaning. The tar content in the producer gas after filtration by using the system varies from 24 to 53.52 mg/m3 . The tar absorption using this filter system was 99.35%, while the pressure drop varied between 10 to 25 mm of the water column. The system was also operated by coupling with a small capacity IC engine. The diesel replacement was found to be in the range of 65.66 %

    Measurements of OH and HO2 concentrations during the MCMA-2006 field campaign – Part 2: Model comparison and radical budget

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    Measurements of hydroxyl (OH) and hydroperoxy (HO2) radicals were made during the Mexico City Metropolitan Area (MCMA) field campaign as part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) project during March 2006. These measurements provide a unique opportunity to test current models of atmospheric ROx (OH + HO2 + RO2) photochemistry under polluted conditions. A zero-dimensional box model based on the Regional Atmospheric Chemical Mechanism (RACM) was constrained by 10-min averages of 24 J-values and the concentrations of 97 chemical species. Several issues related to the ROx chemistry under polluted conditions are highlighted in this study: (i) Measured concentrations of both OH and HO2 were underpredicted during morning hours on a median campaign basis, suggesting a significant source of radicals is missing from current atmospheric models under polluted conditions, consistent with previous urban field campaigns. (ii) The model-predicted HO2/OH ratios underestimate the measurements for NO mixing ratios higher than 5 ppb, also consistent with previous urban field campaigns. This suggests that under high NOx conditions, the HO2 to OH propagation rate may be overestimated by the model or a process converting OH into HO2 may be missing from the chemical mechanism. On a daily basis (08:40 a.m.–06:40 p.m.), an analysis of the radical budget indicates that HONO photolysis, HCHO photolysis, O3-alkene reactions and dicarbonyls photolysis are the main radical sources. O3 photolysis contributes to less than 6% of the total radical production.Henry & Camille Dreyfus FoundationNational Science Foundation (U.S.) (ATM-9984152)National Science Foundation (U.S.) (0612738

    The STAR Photon Multiplicity Detector

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    Details concerning the design, fabrication and performance of STAR Photon Multiplicity Detector (PMD) are presented. The PMD will cover the forward region, within the pseudorapidity range 2.3--3.5, behind the forward time projection chamber. It will measure the spatial distribution of photons in order to study collective flow, fluctuation and chiral symmetry restoration.Comment: 15 pages, including 11 figures; to appear in a special NIM volume dedicated to the accelerator and detectors at RHI

    Rhizome Yield of Sweet Flag ( Acorus calamus

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    A study was undertaken for two consecutive years to assess the possibility of optimizing rhizome yield of Acorus calamus L. (sweet flag) by shifting the time of planting (i.e., growing in rainy and autumn seasons), maintaining different spacings, and harvesting in different months. Significantly higher yields of A. calamus were recorded when seeded in autumn (13150 kg ha−1) than rainy (6570 kg ha−1) season. Harvesting of crop after 12 months gave maximum rhizome yields of 16470 kg ha−1 and 9370 kg ha−1 respectively during autumn and rainy seasons. A similar trend was also noticed in various yield components (i.e., length, width and weight of rhizome). Closer planting (20×20 cm, 30×20 cm) gave significantly higher rhizome yield (8620 kg ha−1, 8120 kg ha−1) than wider spacing 40×40 cm (7030 kg ha−1). This study illustrated the possibility of optimizing rhizome yield of A. calamus by manipulation in the time of planting and harvesting as well as maintaining proper plant spacing

    Indole and 2,4-Thiazolidinedione conjugates as potential anticancer modulators

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    Background. Thiazolidinediones (TZDs), also called glitazones, are five-membered carbon ring molecules commonly used for the management of insulin resistance and type 2 diabetes. Recently, many prospective studies have also documented the impact of these compounds as anti-proliferative agents, though several negative side effects such as hepatotoxicity, water retention and cardiac issues have been reported. In this work, we synthesized twenty-six new TZD analogues where the thiazolidinone moiety is directly connected to an N-heterocyclic ring in order to lower their toxic effects. Methods. By adopting a widely applicable synthetic method, twenty-sixTZDderivatives were synthesized and tested for their antiproliferative activity in MTT and Wound healing assays with PC3 (prostate cancer) and MCF-7 (breast cancer) cells. Results. Three compounds, out of twenty-six, significantly decreased cellular viability and migration, and these effects were even more pronounced when compared with rosiglitazone, a well-known member of the TZD class of antidiabetic agents. As revealed by Western blot analysis, part of this antiproliferative effect was supported by apoptosis studies evaluating BCL-xL and C-PARP protein expression. Conclusion. Our data highlight the promising potential of these TZD derivatives as anti-proliferative agents for the treatment of prostate and breast cancer
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