993 resultados para Systematic Errors


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Objective: To assess the (i) benefits, (ii) harms and (iii) costs of continuing mammographic screening for women 70 years and over. Data sources and synthesis: (i) We conducted a MEDLINE search (1966 - July 2000) for decision-analytic models estimating life-expectancy gains from screening in older women. The five studies meeting the inclusion criteria were critically appraised using standard criteria. We estimated relative benefit from each model's estimate of effectiveness of screening in older women relative to that in women aged 50-69 years using the same model. (ii) With data from BreastScreen Queensland, we constructed balance sheets of the consequences of screening for women in 10-year age groups (40-49 to 80-89 years), and (iii) we used a validated model to estimate the marginal cost-effectiveness of extending screening to women 70 years and over. Results: For women aged 70-79 years, the relative benefit was estimated as 40%-72%, and 18%-62% with adjustment for the impact of screening on quality of life. For women over 80 years the relative benefit was about a third, and with quality-of-life adjustment only 14%, that in women aged 50-69 years. (ii) Of 10 000 Australian women participating in ongoing screening, about 400 are recalled for further testing, and, depending on age, about 70-112 undergo biopsy and about 19-80 cancers are detected. (iii) Cost-effectiveness estimates for extending the upper age limit for mammographic screening from 69 to 79 years range from $8119 to $27 751 per quality-adjusted life-year saved, which compares favourably with extending screening to women aged 40-49 years (estimated at between $24 000 and $65 000 per life-year saved). Conclusions: Women 70 years and over, in consultation with their healthcare providers, may want to decide for themselves whether to continue mammographic screening. Decision-support materials are needed for women in this age group.

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OTseeker (Occupational Therapy Systematic Evaluation of Evidence) is a new resource for occupational therapists that has been designed with the principle aim of increasing access to research to support clinical decisions. It contains abstracts of systematic reviews and quality ratings of randomized controlled trials (RCTs) relevant to occupational therapy. It is available, free of charge, at www.otseeker.com. This paper describes the OTseeker database and provides an example of how it may support occupational therapy practice.

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Acetohydroxyacid synthase (AHAS, EC 4.1.3.18) catalyses the first step in branched-chain amino acid biosynthesis and is the target for sulfonylurea and imidazolinone herbicides, which act as potent and specific inhibitors. Mutants of the enzyme have been identified that are resistant to particular herbicides. However, the selectivity of these mutants towards various sulfonylureas and imidazolinones has not been determined systematically. Now that the structure of the yeast enzyme is known, both in the absence and presence of a bound herbicide, a detailed understanding of the molecular interactions between the enzyme and its inhibitors becomes possible. Here we construct 10 active mutants of yeast AHAS, purify the enzymes and determine their sensitivity to six sulfonylureas and three imidazolinones. An additional three active mutants were constructed with a view to increasing imidazolinone sensitivity. These three variants were purified and tested for their sensitivity to the imidazolinones only. Substantial differences are observed in the sensitivity of the 13 mutants to the various inhibitors and these differences are interpreted in terms of the structure of the herbicide-binding site on the enzyme.

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Pre-oxygenation for endotracheal suctioning for mechanically ventilated infants is routine practice in many neonatal intensive care units. In the present systematic review the evidence to support its use is discussed and the authors conclude that no confident recommendations can be made from the results of this review.

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We analyze the sequences of round-off errors of the orbits of a discretized planar rotation, from a probabilistic angle. It was shown [Bosio & Vivaldi, 2000] that for a dense set of parameters, the discretized map can be embedded into an expanding p-adic dynamical system, which serves as a source of deterministic randomness. For each parameter value, these systems can generate infinitely many distinct pseudo-random sequences over a finite alphabet, whose average period is conjectured to grow exponentially with the bit-length of the initial condition (the seed). We study some properties of these symbolic sequences, deriving a central limit theorem for the deviations between round-off and exact orbits, and obtain bounds concerning repetitions of words. We also explore some asymptotic problems computationally, verifying, among other things, that the occurrence of words of a given length is consistent with that of an abstract Bernoulli sequence.

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Bethylopsis carinatus sp.n., and Epyris chilensis sp.n., from Chile are described and illustrated. Taxonomic data on Chilepyris herbsti Evans, Lytopsenella herbsti (Kieffer), Lytopsenella testaceicornis (Kieffer) and Pseudisobrachium erythrocephalum Evans are included. Male of Lytopsenella herbsti is recorded for the first time to genus and species.

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Diagnosis and genitalia description and illustration of Dissomphalus bicavatusEvans, 1979;D. bispinulatusEvans, 1969;D. brasiliensisKieffer, 1910;Z). caviclypeus Evans, 1969; D. cornutus Evans 1964; D. dumosus, Evans, 1966; D. fungosus Evans, 1979; D. gilvipes Evans, 1979; D. incomptus Evans, 1964; D. infissus Evans, 1969; D. mendicus Evans, 1969; D. microstictus Evans, 1969; D. mirabilis Evans, 1966; D. nanellus Evans, 1969; D. napo Evans, 1979; D. plaumanni Evans, 1964; D. punctatus (Kieffer, 1910); D. puteolus Evans, 1969; D. rufipalpis Kieffer, 1910; D. xanthopus Ashmead, 1893 are provided. Female of D. mirabilis is first described. Five synonymies are proposed: D. connubialis Evans, 1966 of D. brasiliensis, D. montanus Kieffer, 1910 of D. punctatus, D. obliquus Evans, 1979 of D. rufipalpis, D. teren Evans, 1969 of D. cornutus and D. hastatus Evans, 1979 of D. bispinulatus. D. microtuberculatus sp.n. from Northern Argentina is described and illustrated.

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Background: Several studies link the seamless fit of implant-supported prosthesis with the accuracy of the dental impression technique obtained during acquisition. In addition, factors such as implant angulation and coping shape contribute to implant misfit. Purpose: The aim of this study was to identify the most accurate impression technique and factors affecting the impression accuracy. Material and Methods: A systematic review of peer-reviewed literature was conducted analyzing articles published between 2009 and 2013. The following search terms were used: implant impression, impression accuracy, and implant misfit.A total of 417 articles were identified; 32 were selected for review. Results: All 32 selected studies refer to in vitro studies. Fourteen articles compare open and closed impression technique, 8 advocate the open technique, and 6 report similar results. Other 14 articles evaluate splinted and non-splinted techniques; all advocating the splinted technique. Polyether material usage was reported in nine; six studies tested vinyl polysiloxane and one study used irreversible hydrocolloid. Eight studies evaluated different copings designs. Intraoral optical devices were compared in four studies. Conclusions: The most accurate results were achieved with two configurations: (1) the optical intraoral system with powder and (2) the open technique with splinted squared transfer copings, using polyether as impression material.

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This work presents for the first time a systematic study on the optimization of the electrochemical cleaning time of a mercury film when it is used as a working electrode material in the analysis of toxic metals, such as Pb2+, used as model metal, in real samples by SWASV. The optimization study for the film’s cleaning time aimed at attaining a Pb2+ minimum value in the film after the re-oxidation step of the pre-concentrated metal, given the impossibility of complete removal of traces of the electroactive species from the film. This value was kept constant in each concentration range studied ensuring thus that all assays were performed in initial identical conditions. An assay performed on a synthetic sample was taken as reference. In it, given the absence of matrix effects, and after the electrochemical cleaning step, a direct proportionality was observed between the residual amounts of Pb2+ in the film (which for the cleaning time used was never completely removed) and Pb2+ concentration in the solution. This fact determined a high correlation between Pb2+ peak current and Pb2+ concentration which was not observed when real samples (tree leaves) were analyzed. This behavior may result from the presence of the interfering surfactants always present in real samples of complex matrix. Cleaning time optimization was performed for the following Pb2+ concentration ranges in the real samples of complex matrix: 0.006-0.020, 0.020-0.080, 0.060-0.200 and 0.100-0.600 ppb. As expected, in order to obtain identical levels of film’s cleaning efficiency, the need for longer cleaning times has been observed for higher concentrations. The optimized cleaning times for the concentration ranges under study were 120, 150, 180 e 300 s, respectively.

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The mis-evaluation of risk in securitized financial products is central to understanding the global financial crisis. This paper characterizes the evolution of risk factors affecting collateralized debt obligations (CDOs) based on subprime mortgages. A key feature of subprime mortgage-backed indices is that they are distinct in their vintage of issuance. Using a latent factor framework that incorporates this vintage effect, we show the increasing importance of common factors on more senior tranches during the crisis. An innovation of the paper is that we use the unbalanced panel structure of the data to identify the vintage, credit, common and idiosyncratic effects from a state-space specification.

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Introdução – Na avaliação diagnóstica em mamografia, o desempenho do radiologista pode estar sujeito a erros de diagnóstico. Objetivo – Descrever a importância da perceção visual na análise da mamografia, identificando os principais fatores que contribuem para a perceção visual do radiologista e que condicionam a acuidade diagnóstica. Metodologia – Estudo descritivo baseado numa revisão sistemática de literatura através da PubMed e da Science Direct. Foram incluídos 42 artigos que respeitavam, pelo menos, um dos critérios de inclusão no estudo. Para a seleção das referências foi utilizada a metodologia PRISMA, constituída por 4 fases: identificação, seleção preliminar, elegibilidade e estudos incluídos. Resultados – Na avaliação diagnóstica em mamografia, a perceção visual está intimamente relacionada com: 1) diferentes parâmetros visuais e da motilidade ocular (acuidade visual, sensibilidade ao contraste e à luminância e movimentos oculares); 2) com condições de visualização de uma imagem (iluminância da sala e luminância do monitor); e 3) fadiga ocular provocada pela observação diária consecutiva de imagens. Conclusões – A perceção visual pode ser influenciada por 3 categorias de erros observados: erros de pesquisa (lesões não são fixadas pela fóvea), erros de reconhecimento (lesões fixadas, mas não durante o tempo suficiente) e erros de decisão (lesões fixadas, mas não identificadas como suspeitas). Os estudos analisados sobre perceção visual, atenção visual e estratégia visual, bem como os estudos sobre condições de visualização não caracterizam a função visual dos observadores. Para uma avaliação correta da perceção visual em mamografia deverão ser efetuados estudos que correlacionem a função visual com a qualidade diagnóstica. ABSTRACT - Introduction – Diagnostic evaluation in mammography could be influenced by the radiologist performance that could be under diagnostic errors. Aims – To describe the importance of radiologist visual perception in mammographic diagnostic evaluation and to identify the main factors that contribute to diagnostic accuracy. Methods – In this systematic review 42 references were included based on inclusion criteria (PubMed and Science Direct). PRISMA method was used to select the references following 4 steps: identification, screening, eligibility and included references. Results – Visual perception in mammography diagnostic evaluation is related with: 1) visual parameters and ocular motility (visual acuity, contrast sensitivity and luminance and ocular movements); 2) image visualization environment (room iluminance and monitor luminance); and 3) eyestrain caused by image daily consecutive observation. Conclusions – Visual perception can be influenced by three errors categories: search errors (lesions are never looked at with high-resolution foveal vision), recognition errors (lesions are looked at, but not long enough to detect or recognize) and decision errors (lesions are looked at for long periods of time but are still missed). The reviewed studies concerning visual perception, visual attention, visual strategies and image visualization environment do not describe observer’s visual function. An accurate evaluation of visual perception in mammography must include visual function analysis.

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Mestrado em Radiações Aplicadas às Tecnologias da Saúde.

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Purpose: Systematic review to identify the factors associated to the quality of life (QOL) of the caregivers of people with aphasia (PWA). Methods: Studies were searched using Medline, Pubmed, Cochrane Library, CINAHL, PsycINFO and Web of Science databases. Peer-reviewed papers that studied the QOL of PWA’s caregivers or the consequences of aphasia in caregivers’ life were included. Findings were extracted from the studies that met the inclusion criteria. Results: No data is available reporting particularly the QOL of PWA caregivers’ or their QOL predictors. Nevertheless, it was possible to extract aspects related to QOL from the studies that report the consequences of aphasia, and life changes in PWA’s caregivers. Nine (9) studies including PWA’s caregivers were found, but only 5 reported data separately on them. Methodological heterogeneity impedes cross-study comparisons, although some considerations can be made. PWA’s caregivers reported life changes such as: loss of freedom; social isolation; new responsibilities; anxiety; emotional loneliness; need for support and respite. Conclusions: Changes in social relationships, in emotional status, increased burden and need for support and respite were experienced by PWA’s caregivers. Stroke QOL studies need to include PWA caregivers’ and report separately on them. Further research is needed in this area in order to determine their QOL predictors and identify what interventions and referrals better suit their needs.

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Several field methodologies, analytical measures and theoretical patterns have been explored for conservation planning for arthropods in native forests of the Azores archipelago. Here, the outcomes are assembled to make recommendations on practical strategies to assess arthropod diversity and to select and manage protected native forests in the Azores. Suggestions are made on how to apply similar plans for conservation of other plant and animal groups in these forests. Potential threats to the Azorean native forest are described and measures to minimize them are proposed. Future studies are also suggested that would improve the present knowledge of arthropod diversity and distribution in Azorean native forests and could assist in the identification of suitable conservation strategies.