1,234 research outputs found

    Utilization of the termite Hodotermes mossambicus (Hagen) by gekkonid lizards near Keetmanshoop, South West Africa

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    Five species of primarily nocturnal geckos (Ptenopus garrulus maculatus, Chondrodactylus angulifer angulifer, Pachydactylus bibronii, P. mariquensis latirosths and P. punctatus) collected near Keetmanshoop, South West Africa on the night of 3 October 1987 were found to contain large numbers of the harvester termite Hodotermes mossambicus. The mass of termites consumed ranged up to 61,1% of empty gecko body weight. Termite consumption of this magnitude and extensive above-ground foraging by large numbers of Ptenopus appear to be uncommon and probably reflect gecko usage of a large-scale Hodotermes foraging bout associated with the onset of the rainy season. The availability of such a concentrated food resource may be particularly important for vitellogenic female geckos

    Skin mechanics and morphology of two species of Pachydactylus (Reptilia:Gekkonidae)

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    The southern African species Pachydactylus namaquensis is one of only a few mainland species of geckos that exhibits the escape strategy of regional integumentary loss. The skin morphology and mechanics of this species were compared to the same parameters in lhe sympatric congener P. bibronii. The tensile strength and modulus of elasticity of the skin of both species fall in the middle range of values for geckos as a whole. Skin of P. namaquensis,however, has approximately half of the tensile strength of that of P. bibronii. As in other skin-losing forms, the morphological basis for weakness lies in the bilayering of the dermis and the presence of zones of weakness within the upper layer of the dermis. Field experience suggests that P. namaquensis does not lose the skin as easily as most geckos exhibiting regional integumentary loss. In this species this escape strategy has probably evolved in response to the prey subjugation mode employed by rock-dwelling lizard predators

    The Importance of Chain-Length Dependent Kinetics in Free-Radical Polymerization: A Preliminary Guide

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    The effect of chain-length dependent propagation at short chain lengths on the observed kinetics in low-conversion free-radical polymerization (frp) is investigated. It is shown that although the values of individual propagation rate coefficients quickly converge to the high chain length value (at chain lengths, i, of about 10), its effect on the average propagation rate coefficients, kp, in conventional frp may be noticeable in systems with an average degree of polymerization (DPn) of up to 100. Furthermore it is shown that, unless the system is significantly retarded, the chain-length dependence of the average termination rate coefficient, kt, is not affected by the presence of chain-length dependent propagation and that there exists a simple (fairly general) scaling law between kt and DPn. This latter scaling law is a good reflection of the dependence of the termination rate coefficient between two i-meric radicals, kt i,i, on i. Although simple expressions seem to exist to describe the dependence of kp on DPn, the limited data available to date does not allow the generalization of these expressions

    Mapping adaptation of barley to droughted environments

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    Identifying barley genomic regions influencing the response of yield and its components to water deficits will aid in our understanding of the genetics of drought tolerance and the development of more drought tolerant cultivars. We assembled a population of 192 genotypes that represented landraces, old, and contemporary cultivars sampling key regions around the Mediterranean basin and the rest of Europe. The population was genotyped with a stratified set of 50 genomic and EST derived molecular markers, 49 of which were Simple Sequence Repeats (SSRs), which revealed an underlying population sub-structure that corresponded closely to the geographic regions in which the genotypes were grown. A more dense whole genome scan was generated by using Diversity Array Technology (DArTÂź) to generate 1130 biallelic markers for the population. The population was grown at two contrasting sites in each of seven Mediterranean countries for harvest 2004 and 2005 and grain yield data collected. Mean yield levels ranged from 0.3 to 6.2 t/ha, with highly significant genetic variation in low-yielding environments. Associations of yield with barley genomic regions were then detected by combining the DArT marker data with the yield data in mixed model analyses for the individual trials, followed by multiple regression of yield on markers to identify a multi-locus subset of significant markers/QTLs. QTLs exhibiting a pre-defined consistency across environments were detected in bins 4, 6, 6 and 7 on barley chromosomes 3H, 4H, 5H and 7H respectivel

    ‘A more human approach 
 I haven’t found that really’: experiences of hoarding difficulties and seeking help

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    Background and aims: People with hoarding behaviours often struggle to engage in treatment. This study aimed to explore the experiences of a sample of people who identify as engaging in hoarding behaviours and who are seeking support. Exploring motivation to seek help, the barriers those who hoard face in accessing support and what facilitates accepting help, can aid understanding of how best to intervene. Method: Eight individuals who self-identified as seeking help in relation to hoarding behaviours were recruited via social media and support groups. Interviews were conducted by telephone or video call, before being transcribed and analysed using interpretative phenomenological analysis. Results: Participants described complex help-seeking narratives and reported continued ambivalence about addressing their hoarding behaviours. The four group experiential themes identified were Wrestling with identity; Who can I trust?; Services don’t fit; and Being overlooked: ‘they’re too busy looking at the thing, not the person’. Difficulties trusting others and services were identified; services were experienced as rejecting and many participants sought help for problems other than their hoarding. Problems accessing appropriate help for hoarding were predominant in the narratives, although participants who had accessed peer support described this as valuable. Conclusions: There are both internal (e.g. fear of judgement; feeling overwhelmed) and external (e.g. service gaps) barriers that make finding useful help for hoarding behaviours very difficult. Services may facilitate those seeking help by taking a compassionate and person-centred approach to hoarding problems

    Dependence of direct detection signals on the WIMP velocity distribution

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    The signals expected in WIMP direct detection experiments depend on the ultra-local dark matter distribution. Observations probe the local density, circular speed and escape speed, while simulations find velocity distributions that deviate significantly from the standard Maxwellian distribution. We calculate the energy, time and direction dependence of the event rate for a range of velocity distributions motivated by recent observations and simulations, and also investigate the uncertainty in the determination of WIMP parameters. The dominant uncertainties are the systematic error in the local circular speed and whether or not the MW has a high density dark disc. In both cases there are substantial changes in the mean differential event rate and the annual modulation signal, and hence exclusion limits and determinations of the WIMP mass. The uncertainty in the shape of the halo velocity distribution is less important, however it leads to a 5% systematic error in the WIMP mass. The detailed direction dependence of the event rate is sensitive to the velocity distribution. However the numbers of events required to detect anisotropy and confirm the median recoil direction do not change substantially.Comment: 21 pages, 7 figures, v2 version to appear in JCAP, minor change

    Efficacy of increased resistant starch consumption in human type 2 diabetes

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    Resistant starch (RS) has been shown to beneficially affect insulin sensitivity in healthy individuals and those with metabolic syndrome, but its effects on human type 2 diabetes (T2DM) are unknown. This study aimed to determine the effects of increased RS consumption on insulin sensitivity and glucose control and changes in postprandial metabolites and body fat in T2DM. Seventeen individuals with well-controlled T2DM (HbA1c 46.6±2 mmol/mol) consumed, in a random order, either 40 g of type 2 RS (HAM-RS2) or a placebo, daily for 12 weeks with a 12-week washout period in between. At the end of each intervention period, participants attended for three metabolic investigations: a two-step euglycemic–hyperinsulinemic clamp combined with an infusion of [6,6-2H2] glucose, a meal tolerance test (MTT) with arterio-venous sampling across the forearm, and whole-body imaging. HAM-RS2 resulted in significantly lower postprandial glucose concentrations (P=0.045) and a trend for greater glucose uptake across the forearm muscle (P=0.077); however, there was no effect of HAM-RS2 on hepatic or peripheral insulin sensitivity, or on HbA1c. Fasting non-esterified fatty acid (NEFA) concentrations were significantly lower (P=0.004) and NEFA suppression was greater during the clamp with HAM-RS2 (P=0.001). Fasting triglyceride (TG) concentrations and soleus intramuscular TG concentrations were significantly higher following the consumption of HAM-RS2 (P=0.039 and P=0.027 respectively). Although fasting GLP1 concentrations were significantly lower following HAM-RS2 consumption (P=0.049), postprandial GLP1 excursions during the MTT were significantly greater (P=0.009). HAM-RS2 did not improve tissue insulin sensitivity in well-controlled T2DM, but demonstrated beneficial effects on meal handling, possibly due to higher postprandial GLP1

    Processing and mechanical properties of magnesium-lithium composites containing steel fibers

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    Deformation-processed metal-metal composites (DMMC) of Mg-Li alloys containing steel reinforcing fibers were prepared by infiltrating a preform of steel wool with the molten matrix. The Li content was varied to control the crystal structure of the matrix; Mg-4 wt pct Li is hexagonal close packed (hcp), while Mg-12 wt pct Li is body-centered cubic (bcc). The low carbon steel used as the reinforcing fiber is essentially bcc. The hcp/bcc and bcc/bcc composites were subsequently deformed by rolling and by extrusion/swaging and mechanically tested to relate the tensile strength of the composites to true deformation strain. The hcp/bcc composites had limited formability at temperatures up to 400 °C, while the bcc/bcc composites had excellent formability during sheet rolling at room temperature but limited formability during swaging at room temperature. The tensile strengths of the hcp/bcc composite rod and the bcc/bcc composite sheet and rod increased moderately with deformation, though less than predicted from rule-of-mixtures (ROM) calculations. This article presents the experimental data for these DMMC materials and comments on the possible effect of texture development in the matrix and fiber phases on the deformation characteristics of the composite material

    The Millennium Drought in southeast Australia (2001-2009): Natural and human causes and implications for water resources, ecosystems, economy, and society

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    The "Millennium Drought" (2001-2009) can be described as the worst drought on record for southeast Australia. Adaptation to future severe droughts requires insight into the drivers of the drought and its impacts. These were analyzed using climate, water
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