116 research outputs found

    Effects of habitat and livestock on nest productivity of the Asian houbara Chlamydotis macqueenii in Bukhara Province, Uzbekistan

    Get PDF
    To inform population support measures for the unsustainably hunted Asian houbara Chlamydotis macqueenii (IUCN Vulnerable) we examined potential habitat and land-use effects on nest productivity in the Kyzylkum Desert, Uzbekistan. We monitored 177 nests across different semi-arid shrub assemblages (clay-sand and salinity gradients) and a range of livestock densities (0–80 km-2). Nest success (mean 51.4%, 95% CI 42.4–60.4%) was similar across four years; predation caused 85% of those failures for which the cause was known, and only three nests were trampled by livestock. Nesting begins within a few weeks of arrival when food appears scarce, but later nests were more likely to fail owing to the emergence of a key predator, suggesting foraging conditions on wintering and passage sites may be important for nest productivity. Nest success was similar across three shrub assemblages and was unrelated to landscape rugosity, shrub frequency or livestock density, but was greater with taller mean shrub height (range 13–67 cm) within 50 m. Clutch size (mean = 3.2 eggs) and per-egg hatchability in successful nests (87.5%) did not differ with laying date, shrub assemblage or livestock density. We therefore found no evidence that livestock density reduced nest productivity across the range examined, while differing shrub assemblages appeared to offer similar habitat quality. Asian houbara appear well-adapted to a range of semi-desert habitats and tolerate moderate disturbance by pastoralism. No obvious in situ mitigation measures arise from these findings, leaving regulation and control as the key requirement to render hunting sustainable

    Backpack-mounted satellite transmitters do not affect reproductive performance in a migratory bustard

    Get PDF
    Backpack-mounted satellite transmitters (PTTs) are used extensively in the study of avian habitat use and of the movements and demography of medium- to large-bodied species, but can affect individuals’ performance and fitness. Transparent assessment of potential transmitter effects is important for both ethical accountability and confidence in, or adjustment to, life history parameter estimates. We assessed the influence of transmitters on seven reproductive parameters in Asian houbara Chlamydotis macqueenii, comparing 114 nests of 38 females carrying PTTs to 184 nests of untagged birds (non-PTT) over seven breeding seasons (2012‒2018) in Uzbekistan. There was no evidence of any influence of PTTs on: lay date (non-PTT x̅ = 91.7 Julian day ± 12.3 SD; PTT x̅ = 95.1 Julian day ± 15.7 SD); clutch size (non-PTT x̅ = 3.30 ± 0.68 SD; PTT x̅ = 3.25 ± 0.65 SD); mean egg weight at laying (non-PTT x̅ = 66.1g ± 5.4 SD; PTT x̅ = 66.4g ± 5.4 SD); nest success (non-PTT x̅ = 57.08% ± 4.3 SE; PTT x̅ = 58.24% ± 4.5 SE for nests started 2 April); egg hatchability (non-PTT x̅ = 88.3% ± 2.2 SE; PTT x̅ = 88.3% ± 2.6 SE); or chick survival to fledging from broods that had at least one surviving chick (non-PTT x̅ = 63.4% ± 4.2 SE; PTT x̅= 64.4% ± 4.7 SE). High nesting propensity (97.3% year-1 ± 1.9% SE) of tagged birds indicated minimal PTT effect on breeding probability. These findings show harness-mounted transmitters can give unbiased measures of demographic parameters of this species, and are relevant to other large-bodied, cursorial, ground-nesting birds of open habitats, particularly other bustards

    The Forward-Discount Puzzle in Central and Eastern Europe

    Get PDF
    This paper adds to evidence that the forward-discount puzzle is at least partly explained as a compensation for taking crash-risk. A number of Central and Eastern European exchange rates are compared. A Hidden Markov Model is used to identify two regimes for most of the exchange rates. These two regimes can be characterised as being either periods of stability or periods of instability. The level of international risk aversion and changes in US interest rates affect the probability of switching from one regime to the other. This model is then used to assess the way that these two factors affect the probability of a currency crisis. While the Czech Republic, Hungary and Bulgaria are very sensitive to international financial conditions, Poland and Romania are relatively immune. JEL classifications: C24, F31, F32; Key words: Exchange rates, uncovered interest parity, foreign exchange risk discount, hidden-Markov model, carry-trad

    Transplantation of canine olfactory ensheathing cells producing chondroitinase ABC promotes chondroitin sulphate proteoglycan digestion and axonal sprouting following spinal cord injury

    Get PDF
    Olfactory ensheathing cell (OEC) transplantation is a promising strategy for treating spinal cord injury (SCI), as has been demonstrated in experimental SCI models and naturally occurring SCI in dogs. However, the presence of chondroitin sulphate proteoglycans within the extracellular matrix of the glial scar can inhibit efficient axonal repair and limit the therapeutic potential of OECs. Here we have used lentiviral vectors to genetically modify canine OECs to continuously deliver mammalian chondroitinase ABC at the lesion site in order to degrade the inhibitory chondroitin sulphate proteoglycans in a rodent model of spinal cord injury. We demonstrate that these chondroitinase producing canine OECs survived at 4 weeks following transplantation into the spinal cord lesion and effectively digested chondroitin sulphate proteoglycans at the site of injury. There was evidence of sprouting within the corticospinal tract rostral to the lesion and an increase in the number of corticospinal axons caudal to the lesion, suggestive of axonal regeneration. Our results indicate that delivery of the chondroitinase enzyme can be achieved with the genetically modified OECs to increase axon growth following SCI. The combination of these two promising approaches is a potential strategy for promoting neural regeneration following SCI in veterinary practice and human patients

    Estimating geological CO2 storage security to deliver on climate mitigation

    Get PDF
    Carbon capture and storage (CCS) can help nations meet their Paris CO2 reduction commitments cost-effectively. However, lack of confidence in geologic CO2 storage security remains a barrier to CCS implementation. Here we present a numerical program that calculates CO2 storage security and leakage to the atmosphere over 10,000 years. This combines quantitative estimates of geological subsurface CO2 retention, and of surface CO2 leakage. We calculate that realistically well-regulated storage in regions with moderate well densities has a 50% probability that leakage remains below 0.0008% per year, with over 98% of the injected CO2 retained in the subsurface over 10,000 years. An unrealistic scenario, where CO2 storage is inadequately regulated, estimates that more than 78% will be retained over 10,000 years. Our modelling results suggest that geological storage of CO2 can be a secure climate change mitigation option, but we note that long-term behaviour of CO2 in the subsurface remains a key uncertainty

    Landscape determinants of European roller foraging habitat: implications for the definition of agri-environmental measures for species conservation

    Get PDF
    Across much of Europe, farmland birds are declining more than those in other habitats. From a conservation perspective, identifying the primary preferred habitats could help improve the foraging conditions of target species and, consequently, enhance their breeding success and survival. Here, we investigated the ranging behaviour and foraging habitat selection of the European roller (Coracias garrulus) during the breeding season in an agricultural landscape of South Iberia. The occurrence of foraging rollers was predicted to gradually increase with decreasing distance from the nest and increasing availability of perches, such as fences and electric wires. Traditional olive groves and stubble fields were positively and negatively associated with the occurrence of rollers, respectively. Additionally, analysis of hunting strikes showed that rollers highly prefer foraging in fallows rather than cereal or stubble fields. Prey surveys revealed that fallows had the highest abundance of grasshoppers, rollers’ preferred prey during chick-rearing. Pair home-ranges, obtained from 95% fixed Kernel estimators averaged 70.9 ha (range = 34–118 ha) and most foraging trips (80%) occurred in the close vicinity of the nest (<500 m). Number of chicks fledged was not affected by mean foraging distances travelled during the chick-rearing period. Overall, our results suggest that traditional extensive practices of cereal cultivation, with large areas of low-intensity grazed fallows, represent a high-quality foraging habitat for rollers and should be promoted through agri-environmental schemes within at least 1-km radius from the nest. These recommendations are targeted at the roller, but have been shown to apply broadly to several other steppe-bird species

    Staphylococcus aureus infection dynamics

    Get PDF
    Staphylococcus aureus is a human commensal that can also cause systemic infections. This transition requires evasion of the immune response and the ability to exploit different niches within the host. However, the disease mechanisms and the dominant immune mediators against infection are poorly understood. Previously it has been shown that the infecting S. aureus population goes through a population bottleneck, from which very few bacteria escape to establish the abscesses that are characteristic of many infections. Here we examine the host factors underlying the population bottleneck and subsequent clonal expansion in S. aureus infection models, to identify underpinning principles of infection. The bottleneck is a common feature between models and is independent of S. aureus strain. Interestingly, the high doses of S. aureus required for the widely used "survival" model results in a reduced population bottleneck, suggesting that host defences have been simply overloaded. This brings into question the applicability of the survival model. Depletion of immune mediators revealed key breakpoints and the dynamics of systemic infection. Loss of macrophages, including the liver Kupffer cells, led to increased sensitivity to infection as expected but also loss of the population bottleneck and the spread to other organs still occurred. Conversely, neutrophil depletion led to greater susceptibility to disease but with a concomitant maintenance of the bottleneck and lack of systemic spread. We also used a novel microscopy approach to examine abscess architecture and distribution within organs. From these observations we developed a conceptual model for S. aureus disease from initial infection to mature abscess. This work highlights the need to understand the complexities of the infectious process to be able to assign functions for host and bacterial components, and why S. aureus disease requires a seemingly high infectious dose and how interventions such as a vaccine may be more rationally developed

    Biofeedback for training balance and mobility tasks in older populations: a systematic review

    Get PDF
    <p>Abstract</p> <p>Context</p> <p>An effective application of biofeedback for interventions in older adults with balance and mobility disorders may be compromised due to co-morbidity.</p> <p>Objective</p> <p>To evaluate the feasibility and the effectiveness of biofeedback-based training of balance and/or mobility in older adults.</p> <p>Data Sources</p> <p>PubMed (1950-2009), EMBASE (1988-2009), Web of Science (1945-2009), the Cochrane Controlled Trials Register (1960-2009), CINAHL (1982-2009) and PsycINFO (1840-2009). The search strategy was composed of terms referring to biofeedback, balance or mobility, and older adults. Additional studies were identified by scanning reference lists.</p> <p>Study Selection</p> <p>For evaluating effectiveness, 2 reviewers independently screened papers and included controlled studies in older adults (i.e. mean age equal to or greater than 60 years) if they applied biofeedback during repeated practice sessions, and if they used at least one objective outcome measure of a balance or mobility task.</p> <p>Data Extraction</p> <p>Rating of study quality, with use of the Physiotherapy Evidence Database rating scale (PEDro scale), was performed independently by the 2 reviewers. Indications for (non)effectiveness were identified if 2 or more similar studies reported a (non)significant effect for the same type of outcome. Effect sizes were calculated.</p> <p>Results and Conclusions</p> <p>Although most available studies did not systematically evaluate feasibility aspects, reports of high participation rates, low drop-out rates, absence of adverse events and positive training experiences suggest that biofeedback methods can be applied in older adults. Effectiveness was evaluated based on 21 studies, mostly of moderate quality. An indication for effectiveness of visual feedback-based training of balance in (frail) older adults was identified for postural sway, weight-shifting and reaction time in standing, and for the Berg Balance Scale. Indications for added effectiveness of applying biofeedback during training of balance, gait, or sit-to-stand transfers in older patients post-stroke were identified for training-specific aspects. The same applies for auditory feedback-based training of gait in older patients with lower-limb surgery.</p> <p>Implications</p> <p>Further appropriate studies are needed in different populations of older adults to be able to make definitive statements regarding the (long-term) added effectiveness, particularly on measures of functioning.</p
    corecore