Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Virus Evol ; 7(1): veaa093, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34956648

RESUMO

Understanding transmission dynamics that link wild and domestic animals is a key element of predicting the emergence of infectious disease, an event that has highest likelihood of occurring wherever human livelihoods depend on agriculture and animal trade. Contact between poultry and wild birds is a key driver of the emergence of highly pathogenic avian influenza (HPAI), a process that allows for host switching and accelerated reassortment, diversification, and spread of virus between otherwise unconnected regions. This study addresses questions relevant to the spillover of HPAI at a transmission hotspot: what is the nature of the wild bird-poultry interface in Egypt and adjacent Black Sea-Mediterranean countries and how has this contributed to outbreaks occurring worldwide? Using a spatiotemporal model of infection risk informed by satellite tracking of waterfowl and viral phylogenetics, this study identified ecological conditions that contribute to spillover in this understudied region. Results indicated that multiple ducks (Northern Shoveler and Northern Pintail) hosted segments that shared ancestry with HPAI H5 from both clade 2.2.1 and clade 2.3.4 supporting the role of Anseriformes in linking viral populations in East Asia and Africa over large distances. Quantifying the overlap between wild ducks and H5N1-infected poultry revealed an increasing interface in late winter peaking in early spring when ducks expanded their range before migration, with key differences in the timing of poultry contact risk between local and long-distance migrants.

2.
J Mol Graph Model ; 94: 107482, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31683154

RESUMO

In this paper, theoretical calculations for electronic band structure, the density of states, the optical and thermoelectric response of orthorhombic LaXO3 (X = Cr, Mn, Fe) compounds are calculated. The Full Potential Linearized Augmented Plane Wave plus local orbital (FP-LAPW + lo) method is used in the context of density functional theory. Band gaps of three compounds are determined using Wu Cohen Generalized Gradient approximation with additional U potential (WC-GGA + U). Ferromagnetism is observed due to strong p-d hybridization and is justified by observed magnetic moments across individual atoms and at interstitial regions, and exchange constants are also reported. Optical properties are explained by calculating real and imaginary parts of the dielectric function, refractive index (n), extinction coefficient (k), reflection coefficient (R), the absorption coefficient (α), and energy loss spectrum (L). High value of dielectric constant, very small reflectivity and lower energy loss factor in, visible to ultraviolet region favours them for optoelectronic devices. We also computed the thermoelectric properties, including Seebeck coefficient, thermal and electrical conductivity and power factor as a function of temperature by combining results from DFT and Boltzmann transport theory. The phonon dispersion curve shows the stability of the current structures.


Assuntos
Eletrônica , Magnetismo , Condutividade Elétrica , Temperatura
3.
J Mol Graph Model ; 86: 19-26, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30296752

RESUMO

The electronic, mechanical, optical and thermoelectric properties of Cesium based perovskites CsMO3 (M = Nb, Ta) in the cubic phase has been performed through PBEsol-mBJ scheme in the framework of DFT. The electronic band structures and density of states show the studied materials having a direct band gap in the visible range. The mechanical stability and ductile behavior have been analyzed from elastic constants. Moreover, the optical behavior of the studied materials has been analyzed in terms of dielectric functions, refractive index, extinction coefficient, absorption coefficient, optical conductivity, reflectivity and energy loss factor. Finally, the material response with temperature has been elaborated by electrical conductivity, thermal conductivity, Seebeck coefficient, power factor, heat capacity, Hall coefficient, susceptibility and electron density by using BoltzTraP code. This first principle calculation of optical and thermoelectric properties of the novel compounds provides a new route to the experimentalist for the potential application in energy renewable devices.


Assuntos
Compostos de Cálcio/química , Césio/química , Condutividade Elétrica , Fenômenos Mecânicos , Modelos Teóricos , Óxidos/química , Condutividade Térmica , Titânio/química
4.
Ecol Evol ; 7(7): 2025-2038, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28405270

RESUMO

Group foraging contradicts classic ecological theory because intraspecific competition normally increases with aggregation. Hence, there should be evolutionary benefits to group foraging. The study of group foraging in the field remains challenging however, because of the large number of individuals involved and the remoteness of the interactions to the observer. Biologging represents a cost-effective solution to these methodological issues. By deploying GPS and temperature-depth loggers on individuals over a period of several consecutive days, we investigated intraspecific foraging interactions in the Socotra cormorant Phalacrocorax nigrogularis, a threatened colonial seabird endemic to the Arabian Peninsula. In particular, we examined how closely birds from the same colony associated with each other spatially when they were at sea at the same time and the distance between foraging dives at different periods of the day. Results show that the position of different birds overlapped substantially, all birds targeting the same general foraging grounds throughout the day, likely following the same school of fish. There were as many as 44,500 birds within the foraging flock at sea at any time (50% of the colony), and flocking density was high, with distance between birds ranging from 8 to 1,380 m. Birds adopted a diving strategy maximizing time spent underwater relative to surface time, resulting in up to 72% of birds underwater in potential contact with prey at all times while foraging. Our data suggest that the benefits of group foraging outweigh the costs of intense aggregation in this seabird. Prey detection and information transmission are facilitated in large groups. Once discovered, shoaling prey are concentrated under the effect of the multitude. Fish school cohesiveness is then disorganized by continuous attacks of diving birds to facilitate prey capture. Decreasing population size could pose a risk to the persistence of threatened seabirds where group size is important for foraging success.

5.
Clin Pharmacol ; 8: 199-202, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28008288

RESUMO

We report a case of 22-year-old primigravida presented to Women's Hospital - Hamad Medical Corporation emergency with severe epigastric pain, nausea, and vomiting. On admission, she was dehydrated with remarkably worsening symptoms. Laboratory findings revealed significantly elevated liver enzymes with unknown etiology. Her past medical history showed an admission for nausea and vomiting 3 weeks previously and she was discharged on antiemetics, and esomeprazole for the first time. Due to the predominantly elevated liver enzymes, the clinical pharmacist discussed the possibility of esomeprazole-induced adverse effects and suggested to suspend esomeprazole based on the evidence from literature review. The liver enzymes showed a substantial improvement within days after the discontinuation of the drug; however, a rechallenge was not done since it could have adversely affected the mother or the fetus. Using the Naranjo Adverse Drug Reaction Probability scales, the adverse reaction due to esomeprazole was classified as "probably".

6.
J Parasitol ; 93(2): 258-64, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17539407

RESUMO

Questing behavior of Ixodes uriae and their associated seasonal, host-feeding patterns are crucial to our understanding of tick life history strategies and the ecology of diseases that they transmit. Consequently, we quantified questing behavior of nymphs and adult female I. uriae ticks at Gull Island, a seabird colony in Newfoundland, Canada, to examine seasonal variation of off-host and on-host tick activity. We sampled a total of 133 adult Atlantic puffins (Fratercula arctica), 152 puffin chicks, and 145 herring gull (Larus argentatus) chicks for ticks during the breeding seasons of 2004 and 2005. Questing ticks were sampled by dragging a white flannel cloth across the grassy breeding areas during the mo of May, June, July, and August. Nymph questing activity reached a peak during mid-July (79 and 110 individuals/hr in 2004 and 2005, respectively). The prevalence of nymphs and adult female ticks on different seabird hosts varied between years and during the seasons. Puffin chicks had the highest prevalence (above 70% in July) of nymphs in both years and this was correlated with questing activity. Female ticks rarely fed on puffin chicks, but were prevalent on adult puffins and gulls, although prevalence and questing of ticks were not correlated in these hosts. These patterns of off-host and on-host tick activity suggests that I. uriae ticks likely use a combination of questing and passive waiting, e.g., in puffin burrows, to detect hosts, depending on the tick stage and the host species.


Assuntos
Doenças das Aves/parasitologia , Charadriiformes/parasitologia , Ixodes/fisiologia , Infestações por Carrapato/veterinária , Fatores Etários , Animais , Doenças das Aves/epidemiologia , Charadriiformes/fisiologia , Comportamento Alimentar , Feminino , Interações Hospedeiro-Parasita , Ixodes/crescimento & desenvolvimento , Masculino , Terra Nova e Labrador/epidemiologia , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Prevalência , Estações do Ano , Infestações por Carrapato/epidemiologia , Infestações por Carrapato/parasitologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...