855 research outputs found
Inferring Amazon leaf demography from satellite observations of leaf area index
Seasonal and year-to-year variations in leaf cover imprint significant spatial and temporal variability on biogeochemical cycles, and affect land-surface properties related to climate. We develop a demographic model of leaf phenology based on the hypothesis that trees seek an optimal leaf area index (LAI) as a function of available light and soil water, and fit it to spaceborne observations of LAI over the Amazon basin, 2001–2005. We find the model reproduces the spatial and temporal LAI distribution whilst also predicting geographic variation in leaf age from the basin centre (2.1 ± 0.2 years), through to the lowest values over the deciduous eastern and southern Amazon (6 ± 2 months). The model explains the observed increase in LAI during the dry season as a net addition of leaves in response to increased solar radiation. We anticipate our work to be a starting point from which to develop better descriptions of leaf phenology to incorporate into more sophisticated earth system models
Determinants of vaccination coverage and consequences for rabies control in Bali, Indonesia
Maintaining high vaccination coverage is key to successful rabies control, but mass dog vaccination can be challenging and population turnover erodes coverage. Declines in rabies incidence following successive island-wide vaccination campaigns in Bali suggest that prospects for controlling and ultimately eliminating rabies are good. Rabies, however, has continued to circulate at low levels. In the push to eliminate rabies from Bali, high coverage needs to be maintained across all areas of the island. We carried out door-to-door (DTD) questionnaire surveys (n = 10,352 dog-owning households) and photographic mark–recapture surveys (536 line transects, 2,597 observations of free-roaming dogs) in 2011–2012 to estimate dog population sizes and assess rabies vaccination coverage and dog demographic characteristics in Bali, Indonesia. The median number of dogs per subvillage unit (banjar) was 43 (range 0–307) for owned dogs estimated from the DTD survey and 17 (range 0–83) for unconfined dogs (including both owned and unowned) from transects. Vaccination coverage of owned dogs was significantly higher in adults (91.4%) compared to juveniles (<1 year, 43.9%), likely due to insufficient targeting of pups and from puppies born subsequent to vaccination campaigns. Juveniles had a 10–70 times greater risk of not being vaccinated in urban, suburban, and rural areas [combined odds ratios (ORs): 9.9–71.1, 95% CI: 8.6–96.0]. Free-roaming owned dogs were also 2–3 times more likely to be not vaccinated compared to those confined (combined Ors: 1.9–3.6, 95% CI: 1.4–5.4), with more dogs being confined in urban (71.2%) than in suburban (16.1%) and rural areas (8.0%). Vaccination coverage estimates from transects were also much lower (30.9%) than household surveys (83.6%), possibly due to loss of collars used to identify the vaccination status of free-roaming dogs, but these unconfined dogs may also include dogs that were unowned or more difficult to vaccinate. Overall, coverage levels were high in the owned dog population, but for future campaigns in Bali to have the highest chance of eliminating rabies, concerted effort should be made to vaccinate free-roaming dogs particularly in suburban and rural areas, with advertising to ensure that owners vaccinate pups. Long-lasting, cheap, and quick methods are needed to mark vaccinated animals and reassure communities of the reach of vaccination campaigns
Diagnostic criteria for pronival ramparts : site, morphological and sedimentological characteristics
Pronival ramparts are discrete debris accumulations found below steep rock faces at the foot of snowbeds or firn fields but they are often confused with moraines, protalus rock glaciers or rock-slope failure debris accumulations. This can be attributed to a poor understanding of the modes of rampart genesis, failure to recognise the significance of topography in their development and the use of inappropriate diagnostic criteria. Various characteristics have been suggested for identification of pronival ramparts but these are derived largely from relict features. Research on actively accumulating ramparts has shown that some of the suggested criteria are no longer useful. This paper reviews existing criteria and shows that, for diagnostic purposes, more emphasis should be placed on the attributes of actively accumulating features. A more robust set of criteria, derived from common characteristics of actively accumulating ramparts, are proposed that assists in discriminating relict and active pronival ramparts from other discrete bedrock cliff-foot debris accumulations.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1468-0459hb201
Plasma oxidative stress in reproduction of two eusocial African mole‑rat species, the naked mole‑rat and the Damaraland mole‑rat
One of the most prominent life-history trade-offs involves the cost of reproduction. Oxidative stress has been proposed
to be involved in this trade-off and has been associated with reduced life span. There is currently an unclear
relationship between oxidative cost and the reproduction-longevity trade-off. The current study, using a non-lethal
and minimally invasive (only a single blood sample and no euthanasia) method, investigated whether an oxidative
cost (oxidative stress) to reproduction would be apparent in two long-lived eusocial mole-rats, the naked mole-rat
(NMR), Heterocephalus glaber, and the Damaraland mole-rat (DMR), Fukomys damarensis, where breeding colony
members live longer than non-breeder conspecifics. We measured the direct redox balance in plasma by measuring
the oxidative stress index (OSI) based on the ratio of total oxidant status and total antioxidant activity in breeders and
non-breeders of both sexes, in the two species. NMR had significantly higher OSI between breeders and non-breeders
of each sex, whereas DMR showed no significant differences except for total antioxidant capacity (TAC). The mode of
reproductive suppression and the degree of reproductive investment in NMR may explain to some degree the redox
balance difference between breeders and non-breeders. DMR show minimal physiological changes between breeders
and non-breeders except for the mode of reproduction, which may explain some variations in TAC and TOS values,
but similar OSI between breeders and non-breeders.SUPPLEMENTARY MATERIAL : Tables S1 and S2. Sample details and respective TOS (total oxidant status), TAC (total antioxidant capacity) and OSI (oxidative stress index) for Naked mole-rats and for Damaraland mole-rats. NBF: non-breeding females, NBM: non-breeding males, BM: breeding males, BF: breeding females.The SARChI chair of Mammalian Behavioural Ecology and Physiology from the DST-NRF South Africa, the National Research Foundation and the University of Pretoria.http://www.frontiersinzoology.comam2022Mammal Research InstituteZoology and Entomolog
Healthcare-associated outbreak of meticillin-resistant Staphylococcus aureus bacteraemia: role of a cryptic variant of an epidemic clone
BACKGROUND
New strains of meticillin-resistant Staphylococcus aureus (MRSA) may be associated with changes in rates of disease or clinical presentation. Conventional typing techniques may not detect new clonal variants that underlie changes in epidemiology or clinical phenotype.
AIM
To investigate the role of clonal variants of MRSA in an outbreak of MRSA bacteraemia at a hospital in England.
METHODS
Bacteraemia isolates of the major UK lineages (EMRSA-15 and -16) from before and after the outbreak were analysed by whole-genome sequencing in the context of epidemiological and clinical data. For comparison, EMRSA-15 and -16 isolates from another hospital in England were sequenced. A clonal variant of EMRSA-16 was identified at the outbreak hospital and a molecular signature test designed to distinguish variant isolates among further EMRSA-16 strains.
FINDINGS
By whole-genome sequencing, EMRSA-16 isolates during the outbreak showed strikingly low genetic diversity (P < 1 × 10(-6), Monte Carlo test), compared with EMRSA-15 and EMRSA-16 isolates from before the outbreak or the comparator hospital, demonstrating the emergence of a clonal variant. The variant was indistinguishable from the ancestral strain by conventional typing. This clonal variant accounted for 64/72 (89%) of EMRSA-16 bacteraemia isolates at the outbreak hospital from 2006.
CONCLUSIONS
Evolutionary changes in epidemic MRSA strains not detected by conventional typing may be associated with changes in disease epidemiology. Rapid and affordable technologies for whole-genome sequencing are becoming available with the potential to identify and track the emergence of variants of highly clonal organisms
Compound formation and cydrogen activity at sulfided catalysts: A combined surface science and quantum chemical approach
This paper discusses the hydrogen activity of sulfided metal catalysts supported on modified carriers. Surface characterization and theoretical modeling are combined with published studies of planar models to deduce a conceptual model for hydrogen dissociation and mobility on industrial hydrogenation catalysts. The hydrogen activity of metalsulfides is compared with that of the corresponding transition metals. © 1997 Elsevier Science B.V. All rights reserved
An Exploratory Quantitative Study into the Relationship between Catholic Affiliation and the Development of Social Entrepreneurship Education in the USA
Catholic educationalists have long stressed the role of Catholic universities in advancing the cause of social justice to counter the increasing commodification of business relationships and the lack of social responsibilities of the business world. Is this rhetoric or reality? In this empirical paper involving 501 USA universities that have an Association to Advance Collegiate Schools of Business (AACSB) accredited business school, we examine the relationship between Catholic affiliation and the universities’ decisions to offer social entrepreneurship and non-profit management courses to business students. Our study found that universities with Catholic affiliation are significantly more likely to offer both non-profit management and social entrepreneurship courses to business students. Our results offer evidences that Catholic universities are indeed working towards making a difference, with the vision and flexibility to do so
Role of surface roughness in hard x-ray emission from femtosecond laser produced copper plasmas
The hard x-ray emission in the energy range of 30-300 keV from copper plasmas
produced by 100 fs, 806 nm laser pulses at intensities in the range of
10 W cm is investigated. We demonstrate that surface
roughness of the targets overrides the role of polarization state in the
coupling of light to the plasma. We further show that surface roughness has a
significant role in enhancing the x-ray emission in the above mentioned energy
range.Comment: 5 pages, 4 figures, to appear in Phys. Rev.
Population Pharmacokinetic Model and Pharmacokinetic Target Attainment of Micafungin in Intensive Care Unit Patients
_Objective:_ To study the pharmacokinetics of micafungin in intensive care patients and assess pharmacokinetic (PK) target attainment for various dosing strateg
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