Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
1.
Biometrics ; 66(4): 1209-19, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20105156

RESUMO

We introduce a correction for covariate measurement error in nonparametric regression applied to longitudinal binary data arising from a study on human sleep. The data have been surveyed to investigate the association of some hormonal levels and the probability of being asleep. The hormonal effect is modeled flexibly while we account for the error-prone measurement of its concentration in the blood and the longitudinal character of the data. We present a fully Bayesian treatment utilizing Markov chain Monte Carlo inference techniques, and also introduce block updating to improve sampling and computational performance in the binary case. Our model is partly inspired by the relevance vector machine with radial basis functions, where usually very few basis functions are automatically selected for fitting the data. In the proposed approach, we implement such data-driven complexity regulation by adopting the idea of Bayesian model averaging. Besides the general theory and the detailed sampling scheme, we also provide a simulation study for the Gaussian and the binary cases by comparing our method to the naive analysis ignoring measurement error. The results demonstrate a clear gain when using the proposed correction method, particularly for the Gaussian case with medium and large measurement error variances, even if the covariate model is misspecified.


Assuntos
Teorema de Bayes , Estudos Longitudinais/estatística & dados numéricos , Probabilidade , Hormônios/sangue , Humanos , Cadeias de Markov , Método de Monte Carlo , Distribuição Normal , Sono , Fatores de Tempo
2.
J Econ Entomol ; 97(2): 668-77, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15154497

RESUMO

Bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.), male adult (moth) activities were monitored between 1982 and 1995 by using sex pheromone traps in the Texas High Plains. Moths were monitored weekly from early March to mid-November near Lubbock and Halfway, two prominent cotton production areas in the Texas High Plains region. Based on trap captures, the bollworm-budworm complex consisted of approximately 98% bollworms and approximately 2% tobacco budworms. Seasonal activity patterns varied between location for bollworm but not for tobacco budworm. The 14-yr average (+/- SE) bollworm moth abundance (moths per trap per week) at Lubbock was significantly higher (226.5 +/- 10.4) compared with that at Halfway (153.7 +/- 8.1). Correlation analyses showed a significant positive relationship between moth abundance and average weekly temperatures, whereas a significant negative relationship was observed between moth abundance and average weekly wind velocity for both species. Analyses also showed a positive correlation between moth abundance and cumulative degree-days (> 0.0 degrees C) from 1 January. A strong positive relationship was observed between moth abundance and weekly average precipitation for both species. Average weekly abundances were positively correlated between adjacent months during most of the active cotton fruiting season (June-September). However, the relationship between populations that contributed to the overwintering generation and the following spring populations varied between species and study sites. Nevertheless, data from this study indicated that late-season moth catches could be indicative of the dynamics of the early-season moth catches the following year in the High Plains. The mean population abundance curve based on 14-yr averages showed two bollworm population peaks at Lubbock, but only one peak at Halfway. Separate degree-day-based models were developed to describe long-term seasonal abundance patterns of bollworm moths for the Lubbock and Halfway sites.


Assuntos
Mariposas/fisiologia , Animais , Clima , Controle de Insetos , Densidade Demográfica , Estações do Ano , Texas , Fatores de Tempo , Tempo (Meteorologia)
3.
J Econ Entomol ; 95(2): 299-306, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12020004

RESUMO

The study was conducted in the northern Texas Rolling Plains in 1999 to define the relationship between number of cotton aphids, Aphis gossypii Glover, and resulting contamination of cotton lint by honeydew. Whole-plot treatments were three furrow irrigation management treatments: cotton grown without supplemental irrigation (dryland), irrigated cotton with last irrigation in mid August, and irrigated cotton with last irrigation in late August. Subplots within each irrigation treatment included an untreated check, a plot treated with lambda-cyhalothrin to stimulate aphid population increase, a plot treated with lambda-cyhalothrin followed by pymetrozine after aphids began to increase, and a plot treated with lambda-cyhalothrin followed by thiamethoxam after aphids began to increase. Cotton aphids were counted on leaves picked from the top and bottom half of the plant. Cotton lint was analyzed for contamination by glucose, fructose, sucrose, and melezitose secreted by cotton aphids, and percentage leaf moisture and nitrogen and leaf sucrose concentrations were determined. The manual sticky cotton thermodetector was used to determine degree of lint stickinesss. There was a significant relationship between thermodetector counts and melezitose contamination on lint, and a melezitose concentration of 90.9 microg/g of lint was associated with a thermodetector count of 10, the threshold for sticky lint problems in textile mills. An equation was developed to estimate melezitose concentration on lint as a function of average numbers of aphids per leaf and the interaction between percentage leaf moisture and nitrogen. The number of aphids per leaf associated with a melezitose concentration of 90.9 microg/g of lint ranged from 11.1 to 50.1, depending on percentage leaf moisture and nitrogen. The threshold for sticky lint problems occurred when aphid numbers ranged between 11.1 and 50.1 per leaf after bolls open.


Assuntos
Afídeos , Produtos Agrícolas/economia , Gossypium , Controle de Insetos , Agricultura , Animais , Metabolismo dos Carboidratos , Gossypium/metabolismo , Controle de Insetos/métodos , Inseticidas , Neonicotinoides , Nitrilas , Nitrocompostos , Nitrogênio/metabolismo , Oxazinas , Folhas de Planta , Piretrinas , Estações do Ano , Tiametoxam , Tiazóis
5.
Dtsch Med Wochenschr ; 116(6): 212-6, 1991 Feb 08.
Artigo em Alemão | MEDLINE | ID: mdl-1993433

RESUMO

Coronary arteriography revealed severe stenoses of the proximal part of the anterior interventricular branch with normal ventricular function in two patients (aged 42 and 38 years) with stable angina and ischaemia reaction in the exercise ECG. In the first patient it was a short spur-like 80% narrowing. But percutaneous balloon angioplasty failed to change the angiographic appearance. In the other patient there was an eccentric, apparently elastic, 90% stenosis, about 10 mm long. Here, too, balloon angioplasty had failed. Subsequently directional coronary atherectomy in both patients achieved removal of the stenosis with lasting clinical improvement. Atherectomy should be considered in similar cases after failed balloon dilatation.


Assuntos
Angioplastia Coronária com Balão , Doença das Coronárias/cirurgia , Vasos Coronários/cirurgia , Adulto , Angiografia Coronária , Doença das Coronárias/terapia , Eletrocardiografia , Humanos , Masculino
6.
Am J Hum Genet ; 33(4): 640-8, 1981 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-6789676

RESUMO

A genetically determined, polymorphic electrophoretic variant of thyroxin-binding alpha-globulin (TBG) is found in sera from populations of African and Oceania origin, although not in Caucasians nor Orientals. The TBG polymorphism is inherited in X-linked fashion, based on data from American blacks, and thus provides an X-chromosome marker with a relatively high gene frequency in this ethnic group (frequency of the slow allele, TBGs, is 11%). This slow variant should prove valuable in expanding the map of the X chromosome and in linkage studies. An additional family exhibiting X-linked TBG deficiency is also described.


Assuntos
Variação Genética , Polimorfismo Genético , Cromossomos Sexuais , Proteínas de Ligação a Tiroxina/genética , Cromossomo X , Mapeamento Cromossômico , Etnicidade , Feminino , Frequência do Gene , Marcadores Genéticos , Humanos , Ensaio Radioligante
7.
Dtsch Med Wochenschr ; 106(12): 358-62, 1981 Mar 20.
Artigo em Alemão | MEDLINE | ID: mdl-7009123

RESUMO

Transluminal angioplasty according to Grüntzig was performed for 10 stenoses in 7 patients with renovascular hypertension. Nine out of 10 renal artery stenoses were passable and could be dilated. Definite angiographic improvement could be shown in each case. The degree of stenosis could be decreased from 86% to 38% on average. At the narrowest point the diameter was enlarged by a factor of 3.1. The pressure gradient at the stenosis fell on average from 147 to 26 mm Hg. The maximal arterial blood pressure which was on average 254/124 mm Hg before drug treatment, and 169/97 mm Hg after high dosage antihypertensive treatment, fell to 140/84 mm Hg immediately after dilatation. Before dilatation there was a definite increase in peripheral plasma renin activity in every case which fell from 41 to 12 ng AI/ml . h. In one out of 5 patients restenosis occurred after 3 months which could again be successfully dilated. In the two younger patients blood pressure 3 to 9 months later was normal even without antihypertensives. In the older patients normal blood pressure could be maintained with mild antihypertensive treatment.


Assuntos
Hipertensão Renal/terapia , Obstrução da Artéria Renal/terapia , Adulto , Angiografia , Dilatação , Feminino , Humanos , Hipertensão Renal/etiologia , Masculino , Pessoa de Meia-Idade , Obstrução da Artéria Renal/complicações , Obstrução da Artéria Renal/diagnóstico por imagem , Renina/sangue
8.
Am J Hum Genet ; 29(6): 581-92, 1977 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-930924

RESUMO

To detect new genetic variation in human plasma proteins, a panel of 63 radioactive substances were screened as potential radioligands using polyacrylamide gel electrophoresis (PAGE) and autoradiography. Vitamins, hormones, drugs, amino acids, purines, pyrimidines, sugars and lipids labeled with 14C or other radionuclides were among those substances tested. A majority bound to albumin and a smaller fraction to prealbumins and lipoproteins. Several vitamins and hormones bound to specific alpha and beta globulins. (1) Electrophoretic polymorphisms of vitamin D-binding protein (group-specific component), a vitamin B12-binding protein (transcobalamin II), and thyroxine-binding alpha-globulin are described elsewhere. (2) Testosterone-binding beta-globulin (TeBG) showed an electrophoretic polymorphism in Caucasians and a possible deficiency allele. (3) Transcortin showed an electrophoretic doublet in all persons tested but no electrophoretic variation. (4) A protein binding derivative of norepinephrine or epinephrine was identified as transferrin. (5) A nonpolymorphic protein running cathodal to albumin and binding a derivative of riboflavin was tentatively identified as a fraction of albumin with mobility altered as a result of interaction with the ligand.


Assuntos
Proteínas Sanguíneas/genética , Variação Genética , Adulto , Povo Asiático , Autorradiografia/métodos , População Negra , Eletroforese das Proteínas Sanguíneas/métodos , Radioisótopos de Carbono , Radioisótopos de Cobalto , Eletroforese em Gel de Poliacrilamida/métodos , Humanos , Chumbo , Radioisótopos , Ensaio Radioligante , População Branca
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...