1,730 research outputs found
Variations in Remotely-Sensed Phytoplankton Size Structure of a Cyclonic Eddy in the Southwest Indian Ocean
Phytoplankton size classes were derived from weekly-averaged MODIS Aqua chlorophyll a data over the southwest Indian Ocean in order to assess changes in surface phytoplankton community structure within a cyclonic eddy as it propagated across the Mozambique Basin in 2013. Satellite altimetry was used to identify and track the southwesterly movement of the eddy from its origin off Madagascar in mid-June until mid-October, when it eventually merged with the Agulhas Current along the east coast of South Africa. Nano- and picophytoplankton comprised most of the community in the early phase of the eddy development in June, but nanophytoplankton then dominated in austral winter (July and August). Microphytoplankton was entrained into the eddy by horizontal advection from the southern Madagascar shelf, increasing the proportion of microphytoplankton to 23% when the chlorophyll a levels reached a peak of 0.36 mg·m−3 in the third week of July. Chlorophyll a levels declined to 50% of the population. As far as is known, this is the first study to investigate temporal changes in chlorophyll a and community structure in a cyclonic eddy propagating across an ocean basin in the southwest Indian Ocean
Seasonal variation in remotely-sensed phytoplankton size structure around Southern Africa
The three-component model of Brewin et al. (2010) computes fractional contributions of three phytoplankton size classes (micro- (> 20μm), nano- (2–20μm), picophytoplankton ( 1 mgm−3 was limited to shelf regions along the coasts of Southern Africa and Madagascar, while values 50% of the total Chla in these regions with little change throughout the year. The AR shelf differed, with picophytoplankton dominating in summer, and micro- and nanophytoplankton the rest of the year. In the open ocean domains of the NB, SB, and AB regions, nanophytoplankton dominated for most of the year, with picophytoplankton being more prevalent during summer and autumn. In contrast, in the AR open ocean, nanophytoplankton were dominant only during winter and early spring, whereas picophytoplankton dominated throughout the year in the MC open ocean. The refined model characterised previously unknown spatial and temporal changes in size structure in various ecosystems around Southern Africa
Infrared Emission from Supernova Remnants: Formation and Destruction of Dust
We review the observations of dust emission in supernova rem- nants (SNRs)
and supernovae (SNe). Theoretical calculations suggest that SNe, particularly
core-collapse, should make significant quantities of dust, perhaps as much as a
solar mass. Observations of extragalactic SNe have yet to find anywhere near
this amount, but this may be the result of observa- tional limitations. SN
1987A, in the process of transitioning from a SN to an SNR, does show signs of
a significant amount of dust forming in its ejecta, but whether this dust will
survive the passage of the reverse shock to be injected into the ISM is
unknown. IR observations of SNRs have not turned up significant quantities of
dust, and the dust that is observed is generally swept-up by the forward shock,
rather than created in the ejecta. Because the shock waves also destroy dust in
the ISM, we explore the question of whether SNe might be net destroyers, rather
than net creators of dust in the universe.Comment: Published in the Springer Handbook of Supernova
Coastal clustering of HEV; Cornwall, UK.
PublishedBACKGROUND AND AIMS: Autochthonous hepatitis E virus (HEV) infection is a porcine zoonosis and increasingly recognized in developed countries. In most cases the route of infection is uncertain. A previous study showed that HEV was associated geographically with pig farms and coastal areas. AIM: The aim of the present research was to study the geographical, environmental and social factors in autochthonous HEV infection. METHODS: Cases of HEV genotype 3 infection and controls were identified from 2047 consecutive patients attending a rapid-access hepatology clinic. For each case/control the following were recorded: distance from home to nearest pig farm, distance from home to coast, rainfall levels during the 8 weeks before presentation, and socioeconomic status. RESULTS: A total of 36 acute hepatitis E cases, 170 age/sex-matched controls and 53 hepatitis controls were identified. The geographical spread of hepatitis E cases was not even when compared with both control groups. Cases were more likely to live within 2000 m of the coast (odds ratio=2.32, 95% confidence interval=1.08-5.19, P=0.03). There was no regional difference in the incidence of cases and controls between west and central Cornwall. There was no difference between cases and controls in terms of distance from the nearest pig farm, socioeconomic status or rainfall during the 8 weeks before disease presentation. CONCLUSION: Cases of HEV infection in Cornwall are associated with coastal residence. The reason for this observation is uncertain, but might be related to recreational exposure to beach areas exposed to HEV-contaminated 'run-off' from pig farms. This hypothesis merits further study.The European Centre for the Environment and Human Health (part of the Peninsula
College of Medicine and Dentistry which is a joint entity of the University of Exeter,
the University of Plymouth and the NHS in the South West) is supported by
investment from the European Regional Development Fund and the European Social
Fund Convergence Programme for Cornwall and the Isles of Scilly
Electronic Consultation in Primary Care Between Providers and Patients: Systematic Review
Background: Governments and health care providers are keen to find innovative ways to deliver care more efficiently. Interest in electronic consultation (e-consultation) has grown, but the evidence of benefit is uncertain.
Objective: This study aimed to assess the evidence of delivering e-consultation using secure email and messaging or video links in primary care.
Methods: A systematic review was conducted on the use and application of e-consultations in primary care. We searched 7 international databases (MEDLINE, EMBASE, CINAHL, Cochrane Library, PsycINFO, EconLit, and Web of Science; 1999-2017), identifying 52 relevant studies. Papers were screened against a detailed inclusion and exclusion criteria. Independent dual data extraction was conducted and assessed for quality. The resulting evidence was synthesized using thematic analysis.
Results: This review included 57 studies from a range of countries, mainly the United States (n=30) and the United Kingdom (n=13). There were disparities in uptake and utilization toward more use by younger, employed adults. Patient responses to e-consultation were mixed. Patients reported satisfaction with services and improved self-care, communication, and engagement with clinicians. Evidence for the acceptability and ease of use was strong, especially for those with long-term conditions and patients located in remote regions. However, patients were concerned about the privacy and security of their data. For primary health care staff, e-consultation delivers challenges around time management, having the correct technological infrastructure, whether it offers a comparable standard of clinical quality, and whether it improves health outcomes.
Conclusions: E-consultations may improve aspects of care delivery, but the small scale of many of the studies and low adoption rates leave unanswered questions about usage, quality, cost, and sustainability. We need to improve e-consultation implementation, demonstrate how e-consultations will not increase disparities in access, provide better reassurance to patients about privacy, and incorporate e-consultation as part of a manageable clinical workflow
Insights from Amphioxus into the Evolution of Vertebrate Cartilage
Central to the story of vertebrate evolution is the origin of the vertebrate head, a problem difficult to approach using paleontology and comparative morphology due to a lack of unambiguous intermediate forms. Embryologically, much of the vertebrate head is derived from two ectodermal tissues, the neural crest and cranial placodes. Recent work in protochordates suggests the first chordates possessed migratory neural tube cells with some features of neural crest cells. However, it is unclear how and when these cells acquired the ability to form cellular cartilage, a cell type unique to vertebrates. It has been variously proposed that the neural crest acquired chondrogenic ability by recruiting proto-chondrogenic gene programs deployed in the neural tube, pharynx, and notochord. To test these hypotheses we examined the expression of 11 amphioxus orthologs of genes involved in neural crest chondrogenesis. Consistent with cellular cartilage as a vertebrate novelty, we find that no single amphioxus tissue co-expresses all or most of these genes. However, most are variously co-expressed in mesodermal derivatives. Our results suggest that neural crest-derived cartilage evolved by serial cooption of genes which functioned primitively in mesoderm
Copper deficiency and effects of copper supplementation in a herd of red deer (Cervus elaphus)
Copper (Cu) deficiency was diagnosed in a Norwegian red deer (Cervus elaphus) herd subsequent to deaths due to emaciation in late autumn 1999. The animals had free access to salt licks containing 3000 mg Cu/kg. An evaluation of the herd revealed poor calf growth rate, low weights of adult hinds, dull and light-coloured hair coats and cases of diarrhoea. The herd was subsequently monitored throughout a three-year period of Cu-supplementation. The monitoring regimen included clinical observation, copper serum examination, weighing, faecal parasitological examination, and reproduction control by ultrasound. During the period January 2000 to May 2001, the animals were treated with Cu oxid capsules (1 g CuO/10 kg liveweight) at 2–4 months intervals, with the exception of March to September 2000. The animals were fed continuously with Cu-enriched concentrates containing 300 mg Cu/kg, at a rate of 1/2 kg per head and day, from May 2001 to January 2003. Following both copper supplementation regimens adequate serum Cu concentrations were measured, and markedly improved body weights, coat quality and reproductive results were observed, except for the period from March to September 2000 when no treatment was given. The results showed that in a deer herd, with a diet low in Cu, supplementation with CuO capsules had to be given at intervals of a few months to maintain adequate serum Cu levels. Free access to Cu-containing salt licks did not meet the animals' Cu demand. Good and stable results were achieved by the daily feeding of Cu-enriched concentrates
The origin of dust in galaxies revisited: the mechanism determining dust content
The origin of cosmic dust is a fundamental issue in planetary science. This
paper revisits the origin of dust in galaxies, in particular, in the Milky Way,
by using a chemical evolution model of a galaxy composed of stars, interstellar
medium, metals (elements heavier than helium), and dust. We start from a review
of time-evolutionary equations of the four components, and then, we present
simple recipes for the stellar remnant mass and yields of metal and dust based
on models of stellar nucleosynthesis and dust formation. After calibrating some
model parameters with the data from the solar neighborhood, we have confirmed a
shortage of the stellar dust production rate relative to the dust destruction
rate by supernovae if the destruction efficiency suggested by theoretical works
is correct. If the dust mass growth by material accretion in molecular clouds
is active, the observed dust amount in the solar neighborhood is reproduced. We
present a clear analytic explanation of the mechanism for determining dust
content in galaxies after the activation of accretion growth: a balance between
accretion growth and supernova destruction. Thus, the dust content is
independent of the uncertainty of the stellar dust yield after the growth
activation. The timing of the activation is determined by a critical metal mass
fraction which depends on the growth and destruction efficiencies. The solar
system formation seems to have occurred well after the activation and plenty of
dust would have existed in the proto-solar nebula.Comment: 12 pages, 11 figure
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