9,629 research outputs found

    A Generative Model for Parts-based Object Segmentation

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    The Shape Boltzmann Machine (SBM) [1] has recently been introduced as a stateof-the-art model of foreground/background object shape. We extend the SBM to account for the foreground object’s parts. Our new model, the Multinomial SBM (MSBM), can capture both local and global statistics of part shapes accurately. We combine the MSBM with an appearance model to form a fully generative model of images of objects. Parts-based object segmentations are obtained simply by performing probabilistic inference in the model. We apply the model to two challenging datasets which exhibit significant shape and appearance variability, and find that it obtains results that are comparable to the state-of-the-art. There has been significant focus in computer vision on object recognition and detection e.g. [2], but a strong desire remains to obtain richer descriptions of objects than just their bounding boxes. One such description is a parts-based object segmentation, in which an image is partitioned into multiple sets of pixels, each belonging to either a part of the object of interest, or its background. The significance of parts in computer vision has been recognized since the earliest days of th

    Racial Disparities in Cancer Screening Among Women with Chronic Joint Pain

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    Chronic pain related disorders and breast and cervical cancer are more prevalent among African-American women compared with non-Hispanic White women. However, few studies address how racial differences in the context of comorbidity may compound these disparities. This study used secondary analysis of the National Health Interview Survey (NHIS) to assess racial differences in breast and cervical cancer screening and patient education among adult women with chronic joint pain conditions. Statistical analyses included chi-square and independent samples t-tests. African-American women compared with non-Hispanic White women were less likely to receive a pap smear or mammogram within the last two years and receive patient education (p\u3c0.01). Due to competing demands, women with chronic joint pain may not receive preventive services. The results of this study can be used to formulate interventions and evaluate approaches to reduce racial disparities in outpatient service delivery in terms of continuity and scope of care

    Magnification factors for the GTM algorithm

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    The Generative Topographic Mapping (GTM) algorithm of Bishop et al. (1997) has been introduced as a principled alternative to the Self-Organizing Map (SOM). As well as avoiding a number of deficiencies in the SOM, the GTM algorithm has the key property that the smoothness properties of the model are decoupled from the reference vectors, and are described by a continuous mapping from a lower-dimensional latent space into the data space. Magnification factors, which are approximated by the difference between code-book vectors in SOMs, can therefore be evaluated for the GTM model as continuous functions of the latent variables using the techniques of differential geometry. They play an important role in data visualization by highlighting the boundaries between data clusters, and are illustrated here for both a toy data set, and a problem involving the identification of crab species from morphological data

    Magnification factors for the SOM and GTM algorithms

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    Magnification factors specify the extent to which the area of a small patch of the latent (or `feature') space of a topographic mapping is magnified on projection to the data space, and are of considerable interest in both neuro-biological and data analysis contexts. Previous attempts to consider magnification factors for the self-organizing map (SOM) algorithm have been hindered because the mapping is only defined at discrete points (given by the reference vectors). In this paper we consider the batch version of SOM, for which a continuous mapping can be defined, as well as the Generative Topographic Mapping (GTM) algorithm of Bishop et al. (1997) which has been introduced as a probabilistic formulation of the SOM. We show how the techniques of differential geometry can be used to determine magnification factors as continuous functions of the latent space coordinates. The results are illustrated here using a problem involving the identification of crab species from morphological data

    GTM: the generative topographic mapping

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    Latent variable models represent the probability density of data in a space of several dimensions in terms of a smaller number of latent, or hidden, variables. A familiar example is factor analysis which is based on a linear transformations between the latent space and the data space. In this paper we introduce a form of non-linear latent variable model called the Generative Topographic Mapping, for which the parameters of the model can be determined using the EM algorithm. GTM provides a principled alternative to the widely used Self-Organizing Map (SOM) of Kohonen (1982), and overcomes most of the significant limitations of the SOM. We demonstrate the performance of the GTM algorithm on a toy problem and on simulated data from flow diagnostics for a multi-phase oil pipeline

    Delayed Expected Loss Recognition and the Risk Profile of Banks

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    This paper investigates the extent to which delayed expected loan loss recognition (DELR) is associated with greater vulnerability of banks to three distinct dimensions of risk: (1) stock market liquidity risk, (2) downside tail risk of individual banks, and (3) codependence of downside tail risk among banks. We hypothesize that DELR increases vulnerability to downside risk by creating expected loss overhangs that threaten future capital adequacy and by degrading bank transparency, which increases financing frictions and opportunities for risk‐shifting. We find that DELR is associated with higher correlations between bank‐level illiquidity and both aggregate banking sector illiquidity and market returns (i.e., higher liquidity risks) during recessions, suggesting that high DELR banks as a group may simultaneously face elevated financing frictions and enhanced opportunities for risk‐shifting behavior in crisis periods. With respect to downside risk, we find that during recessions DELR is associated with significantly higher risk of individual banks suffering severe drops in their equity values, where this association is magnified for banks with low capital levels. Consistent with increased systemic risk, we find that DELR is associated with significantly higher codependence between downside risk of individual banks and downside risk of the banking sector. We theorize that downside risk vulnerability at the individual bank level can translate into systemic risk by virtue of DELR creating a common source of risk vulnerability across high DELR banks simultaneously, which leads to risk codependence among banks and systemic effects from banks acting as part of a herd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111770/1/joar12079.pd

    Large Culvert Inspection Procedures: Guidelines for INDOT

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    Within the state of Indiana, there are approximately 9,000 structures with unsupported span lengths that range from 4 ft to 20 ft that the Indiana Department of Transportation (INDOT) is responsible for maintaining. These structures are referred to as large culverts by INDOT. The agency recognized the need to improve culvert inspection procedures so that inspection data that is collected can provide essential information to asset engineers who make decisions regarding culvert management. The purpose of the project described in this report was to identify best practices for the inspection and management of these structures to develop guidelines that optimize the resources allocated for the maintenance and inspection of large culvert structures. This study found that standardizing the inspection process and evaluation criteria for inspection will positively impact the overall performance of the inventory of these structures. A proposed large culvert inspection manual accompanies this report and provides a detailed guide for large culvert inspection
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