The Effect of Particle Strength on the Ballistic Resistance of Shear Thickening Fluids

The response of shear thickening fluids (STFs) under ballistic impact has received considerable attention due to its field-responsive nature. While efforts have primarily focused on the response of traditional ballistic fabrics impregnated with fluids, the response of pure STFs to penetration has received limited attention. In the present study, the ballistic response of pure STFs is investigated and the effect of fluid density and particle strength on ballistic performance is isolated. The loss of ballistic resistance of STFs at higher impact velocities is governed by particle strength, indicating the range of velocities over which they may provide effective armor solutions.Comment: 4 pages, 4 figure

Birds and Mammals of Coats Island, N.W.T.

We summarize records of birds and mammals obtained at Coats Island, Northwest Territories during one visit by a National Museum of Natural Sciences expedition and fourteen visits by Canadian Wildlife Service field crews to the northeast corner of the island, as well as records obtained from the journals of the Hudson's Bay Company post active on the island from 1920 to 1924. The terrestrial mammal fauna is very depauperate, lacking any small herbivores. Consequently, predators specializing in small mammals - such as ermine, snowy owl, and long-tailed jaeger, all common on nearby Southampton Island - are rare or absent from Coats Island, except in passage. In addition, there are no snow goose colonies on Coats Island, although good numbers of Canada geese breed there, and some brant may also do so. This means that grazing on the island is mainly confined to the resident caribou population. The absence of small mammals and the relatively low density of geese may have accounted for the poor results of fox trapping during the period when the Hudson's Bay Company post was operating. Numbers of most marine mammals appear to have changed little since the 1920s, although bowhead whales may have become rarer, with only two sightings since 1981, compared to several annually in the 1920s. Winter records from the 1920-24 post journals suggest that waters off Coats Island are within the wintering range of beluga, walrus, and thick-billed murres. Eighty-four species of birds have been seen since 1975; this number includes many sightings of vagrant birds well outside their normal ranges. This may be accounted for by the comparative lushness of the vegetation surrounding the thick-billed murre colony, which attracts birds from long distances.On a fait un sommaire des relevés d'oiseaux et de mammifères obtenus à l'île Coats (Territoires du Nord-Ouest) durant la visite d'une expédition du Musée national des sciences naturelles et 14 visites effectuées par des équipes de terrain du Service canadien de la faune dans l'angle nord-est de l'île, ainsi que des relevés provenant des livres du comptoir de la Compagnie de la baie d'Hudson, qui était en activité dans l'île entre 1920 et 1924. La faune des mammifères terrestres est extrêmement démunie, ne comptant aucun petit herbivore. Cela explique que les prédateurs spécialisés dans les petits mammifères comme l'hermine, le harfang des neiges et le labbe à longue queue - tous communs dans l'île de Southampton avoisinante - soient rares ou absents dans l'île Coats, sauf de façon transitoire. Il n'y a en outre pas de colonies d'oies des neiges dans cette île, bien que nombre de bernaches du Canada s'y reproduisent et peut-être quelques bernaches cravants. Cela signifie que l'herbe est surtout broutée par la population locale des caribous. L'absence de petits mammifères et la densité relativement faible des oies pourraient expliquer les piètres résultats du piégeage du renard au cours de la période d'activité du comptoir de la Compagnie de la baie d'Hudson. Pour la plupart des mammifères marins, le nombre semble n'avoir que peu changé depuis les années 1920, bien que la baleine boréale soit devenue plus rare, ayant fait l'objet de seulement deux observations depuis 1981 en comparaison de plusieurs par an dans les années 1920. Les livres du comptoir qui portent sur les hivers de 1920 à 1924 suggèrent que les eaux au large de l'île Coats sont situées à l'intérieur les limites du territoire hivernal du bélouga, du morse et de la marmette de Brünnich. Depuis 1975, on a aperçu 84 espèces d'oiseaux, comprenant toutefois de nombreuses espèces vagabondes totalement en dehors de leur territoire normal. Ce phénomène peut s'expliquer par la richesse comparative de la végétation entourant la colonie de marmettes de Brünnich, qui attire les oiseaux depuis de grandes distances

Modeling low-flow bedrock springs providing ecological habitats with climate change scenarios

Groundwater discharge areas, including low-flow bedrock aquifer springs, are ecologically important and can be impacted by climate change. The development of and results from a groundwater modeling study simulating fractured bedrock spring flow are presented. This was conducted to produce hydrological data for an ecohydrological study of an endangered species, Allegheny Mountain Dusky Salamanders (Desmognathus ochrophaeus), in southern Quebec, Canada. The groundwater modeling approach in terms of scale and complexity was strongly driven by the need to produce hydrological data for the related ecohydrological modeling. Flows at four springs at different elevations were simulated for recent past conditions (2006–2010) and for reference (1971–2000) and future (2041–2070) periods using precipitation and temperature data from ten climate scenarios. Statistical analyses of spring flow parameters including activity periods and duration of flow were conducted. Flow rates for the four simulated springs, located at different elevations, are predicted to increase between 2% and 46% and will be active (flowing) 1–2% longer in the future. A significant change (predominantly an increase) looking at the seasonality of the number of active days occurs in the winter (2–4.9%) and spring seasons (−0.6–6.5%). Greatest flow rates were produced from springs at elevations where sub-horizontal fractures intersect the ground surface. These results suggest an intensification of the spring activity at the study site in context of climate change by 2050, which provides a positive habitat outlook for the endangered salamanders residing in the springs for the future

Nucleolar Localization of HIV-1 Rev Is Required, Yet Insufficient for Production of Infectious Viral Particles.

Combination antiretroviral therapy fails in complete suppression of HIV-1 due to drug resistance and persistent latency. Novel therapeutic intervention requires knowledge of intracellular pathways responsible for viral replication, specifically those untargeted by antiretroviral drugs. An understudied phenomenon is the nucleolar localization of Rev phosphoprotein, which completes nucleocytoplasmic transport of unspliced/partially spliced HIV mRNA through multimerization with intronic cis-acting targets-the Rev-response element (RRE). Rev contains a nucleolar localization signal (NoLS) comprising the COOH terminus of the arginine-rich motif for accumulation within nucleoli-speculated as the interaction ground for Rev with cellular proteins mediating mRNA-independent nuclear export and splicing. Functionality of Rev nucleolar access during HIV-1 production and infection was investigated in the context of deletion and single-point mutations within Rev-NoLS. Mutations induced upon Rev-NoLS are hypothesized to inactivate the HIV-1 infectious cycle. HIV-1HXB2 replication ceased with Rev mutations lacking nucleolar access due to loss or replacement of multiple arginine residues. Rev mutations missing single arginine residues remained strictly nucleolar in pattern and participated in proviral production, however, with reduced efficiency. Viral RNA packaging also decreased in efficiency after expression of nucleolar-localizing mutations. These results were observed during propagation of variant HIV-1NL4-3 containing nucleolar-localizing mutations within the viral backbone (M4, M5, and M6). Lentiviral particles produced with Rev single-point mutations were transducible at extremely low frequency. Similarly, HIV-1NL4-3 Rev-NoLS variants lost infectivity, unlike virulent WT (wild type) HIV-1NL4-3. HIV-1NL4-3 variants were capable of CD4+ host entry and reverse transcription as WT HIV-1NL4-3, but lacked ability to complete a full infectious cycle. We currently reveal that viral integration is deregulated in the presence of Rev-NoLS mutations

Microarray study reveals that HIV-1 induces rapid type-I interferon-dependent p53 mRNA up-regulation in human primary CD4+ T cells

<p>Abstract</p> <p>Background</p> <p>Infection with HIV-1 has been shown to alter expression of a large array of host cell genes. However, previous studies aimed at investigating the putative HIV-1-induced modulation of host gene expression have been mostly performed in established human cell lines. To better approximate natural conditions, we monitored gene expression changes in a cell population highly enriched in human primary CD4⁺T lymphocytes exposed to HIV-1 using commercial oligonucleotide microarrays from Affymetrix.</p> <p>Results</p> <p>We report here that HIV-1 influences expression of genes related to many important biological processes such as DNA repair, cellular cycle, RNA metabolism and apoptosis. Notably, expression of the p53 tumor suppressor and genes involved in p53 homeostasis such as GADD34 were up-regulated by HIV-1 at the mRNA level. This observation is distinct from the previously reported p53 phosphorylation and stabilization at the protein level, which precedes HIV-1-induced apoptosis. We present evidence that the HIV-1-mediated increase in p53 gene expression is associated with virus-mediated induction of type-I interferon (i.e. IFN-α and IFN-β).</p> <p>Conclusion</p> <p>These observations have important implications for our understanding of HIV-1 pathogenesis, particularly in respect to the virus-induced depletion of CD4⁺T cells.</p

Induction of galectin-1 expression by HTLV-I Tax and its impact on HTLV-I infectivity

© 2008 Gauthier et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Dermal fibroblasts from patients with Parkinson’s disease have normal GCase activity and autophagy compared to patients with PD and GBA mutations

Background: Recently, the development of Parkinson’s disease (PD) has been linked to a number of genetic risk factors, of which the most common is glucocerebrosidase (GBA) mutations. Methods: We investigated PD and Gaucher Disease (GD) patient derived skin fibroblasts using biochemistry assays. Results: PD patient derived skin fibroblasts have normal glucocerebrosidase (GCase) activity, whilst patients with PD and GBA mutations have a selective deficit in GCase enzyme activity and impaired autophagic flux. Conclusions: This data suggests that only PD patients with a GBA mutation have altered GCase activity and autophagy, which may explain their more rapid clinical progression.We are grateful to an NIHR award of a Biomedical Research Centre to Addenbrookes Hospital and the University of Cambridge. We are also grateful to the Rosetrees Trust, the WT-MRC Stem Cell Institute and the Canadian Institutes of Health Research (CIHR) fellowship (358492) for the funding for this work