640 research outputs found

    Adaptive Evaluation Methodology Prototypes: Examples

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    Flexibility or adaptivity in public program evaluation can lead to large savings in time and money, with little or no loss in accuracy, if used properly. In this paper, guidelines are suggested for the employment of classical statistics in adaptive evaluation methodology. Through the case setting of a flu clinic, candidate techniques are demonstrated for handling problems in hypothesis testing, estimation, adaptive allocation of information-gathering resources, and before-and-after-type comparisons. In some cases, classical statistics proves quite adaptable to the requirements of the situation, while in others, its introduction is more artificial

    Preliminary Survey of Classical Statistical Techniques for Incorporation into Adaptive Evaluation Methodology

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    Evaluation of public programming currently tends toward plans that are set in advance of any sampling and adhered to throughout. Because increments in the knowledge profile during the course of an evaluation might beckon adjustment of the working procedure, fixed evaluation methodology may be cost-inefficient. It is desired to develop a methodology that is adaptive to changes in the knowledge profile. This might be most easily accomplished by borrowing ideas from some of the disciplines in which relevant problems occur. The most promising fields for this task include classical and Bayesian statistics, reliability theory, and dynamic programming. This paper reviews the techniques in classical statistics that seem most apt for handling the problem of adaptive changes in an evaluation to updated knowledge profiles, and considers the paths along which future research ought to be conducted

    The boiling suppression of liquid nitrogen

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    When He gas is injected from room temperature into boiling liquid N2_{2}, boiling is suppressed, leaving liquid surface flat like a mirror. Although the qualitative explanation for this phenomenon is known [Minkoff G J \textit{et al}. Nature 1957;180(4599):1413-4.], it has not been studied quantitatively and comprehensively yet. In this report, we made careful simultaneous measurements of temperature and weight variation of the liquid. The results clearly indicate that the boiling suppression is caused by cooling of the liquid with "internal evaporation" of N2_{2} into the He bubbles.Comment: 14 pages, 7 figure

    Hybrid time-domain and continuous-wave diffuse optical tomography instrument with concurrent, clinical magnetic resonance imaging for breast cancer imaging

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    Diffuse optical tomography has demonstrated significant potential for clinical utility in the diagnosis and prognosis of breast cancer, and its use in combination with other structural imaging modalities improves lesion localization and the quantification of functional tissue properties. Here, we introduce a hybrid diffuse optical imaging system that operates concurrently with magnetic resonance imaging (MRI) in the imaging suite, utilizing commercially available MR surface coils. The instrument acquires both continuous-wave and time-domain diffuse optical data in the parallel-plate geometry, permitting both absolute assignment of tissue optical properties and three-dimensional tomography; moreover, the instrument is designed to incorporate diffuse correlation spectroscopic measurements for probing tissue blood flow. The instrument is described in detail here. Image reconstructions of a tissue phantom are presented as an initial indicator of the system's ability to accurately reconstruct optical properties and the concrete benefits of the spatial constraints provided by concurrent MRI. Last, we briefly discuss how various data combinations that the instrument could facilitate, including tissue perfusion, can enable more comprehensive assessment of lesion physiology

    Radiographic Image Enhancement by Wiener Decorrelation

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    The primary focus of the application of image processing to radiography is the problem of segmentation. The general segmentation problem has been attacked on a broad front [1, 2], and thresholding, in particular, is a popular method [1, 3-6]. Unfortunately, geometric unsharpness destroys the crisp edges needed for unambiguous decisions, and this difficulty can be considered a problem in filtering in which the object is to devise a high-pass (sharpening) filter. This approach has been studied for more than 20 years [7-13]

    Prevalence and cumulative incidence of abnormal cervical cytology among HIV-infected Thai women: a 5.5-year retrospective cohort study

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    <p>Abstract</p> <p>Background</p> <p>Cervical cancer is one of the most common AIDS-related malignancies in Thailand. To prevent cervical cancer, The US Public Health Service and The Infectious Disease Society of America have recommended that all HIV-infected women should obtain 2 Pap smears 6 months apart after the initial HIV diagnosis and, if results of both are normal, should undergo annual cytological screening. However, there has been no evidence in supporting whether this guideline is appropriate in all settings - especially in areas where HIV-infected women are living in resource-constrained condition.</p> <p>Methods</p> <p>To determine the appropriate interval of Pap smear screenings for HIV-infected Thai women and risk factors for subsequent abnormal cervical cytology, we assessed the prevalence, cumulative incidence and associated factors of cervical cell abnormalities (atypical squamous cell of undetermined significance or higher grades, ASCUS+) among this group of patients.</p> <p>Results</p> <p>The prevalence of ASCUS+ was 15.4% at the first visit, and the cumulative incidence of ASCUS+ gradually increased to 37% in the first 3.5 years of follow-up appointments (first 7 times), and tended to plateau in the last 2 years. For multivariate correlation analysis, women with a CD4 count <350 cells/ÎĽL had a significant correlation with ASCUS+ (<it>P </it>= 0.043). There were no associations of subsequent ASCUS+ with age, pregnancy, contraceptive method, highly active anti-retroviral treatment, assumed duration of infection, or the CD4 count nadir level.</p> <p>Conclusion</p> <p>There are high prevalence and cumulative incidence of ASCUS+ in HIV-infected Thai women. With a high lost-to-follow-up rate, an appropriate interval of Pap smear screening cannot be concluded from the present study. Nevertheless, the HIV-infected Thai women may require more than two normal semi-annual Pap smears before shifting to routinely annual cytologic screening.</p

    Beyond belief: Strategic taboos and organizational identity in strategic agenda setting

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    A comprehensive strategic agenda matters for fundamental strategic change. Our study seeks to explore and theorize how organizational identity beliefs influence the judgment of strategic actors when setting an organization’s strategic agenda. We offer the notion of “strategic taboo” as those strategic options initially disqualified and deemed inconsistent with the organizational identity beliefs of strategic actors. Our study is concerned with how strategic actors confront strategic taboos in the process of setting an organization’s strategic agenda. Based on a revelatory inductive case study, we find that strategic actors engage in assessing the concordance of the strategic taboos with organizational identity beliefs and, more specifically, that they focus on key identity elements (philosophy; priorities; practices) when doing so. We develop a typology of three reinterpretation practices that are each concerned with a key identity element. While contextualizing assesses the potential concordance of a strategic taboo with an organization’s overall philosophy and purpose, instrumentalizing assesses such concordance with respect to what actors deem an organization’s priorities to be. Finally, normalizing explores concordance with respect to compatibility and fit with the organization’s practices. We suggest that assessing concordance of a strategic taboo with identity elements consists in reinterpreting collective identity beliefs in ways that make them consistent with what organizational actors deem the right course of action. This article discusses the implications for theory and research on strategic agenda setting, strategic change, a practice-based perspective on strategy, and on organizational identity. © The Author(s) 2014
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