Science.gov

Sample records for active contour neighborhood

  1. Brain extraction from cerebral MRI volume using a hybrid level set based active contour neighborhood model

    PubMed Central

    2013-01-01

    Background The extraction of brain tissue from cerebral MRI volume is an important pre-procedure for neuroimage analyses. The authors have developed an accurate and robust brain extraction method using a hybrid level set based active contour neighborhood model. Methods The method uses a nonlinear speed function in the hybrid level set model to eliminate boundary leakage. When using the new hybrid level set model an active contour neighborhood model is applied iteratively in the neighborhood of brain boundary. A slice by slice contour initial method is proposed to obtain the neighborhood of the brain boundary. The method was applied to the internet brain MRI data provided by the Internet Brain Segmentation Repository (IBSR). Results In testing, a mean Dice similarity coefficient of 0.95±0.02 and a mean Hausdorff distance of 12.4±4.5 were obtained when performing our method across the IBSR data set (18 × 1.5 mm scans). The results obtained using our method were very similar to those produced using manual segmentation and achieved the smallest mean Hausdorff distance on the IBSR data. Conclusions An automatic method of brain extraction from cerebral MRI volume was achieved and produced competitively accurate results. PMID:23587217

  2. Neighborhood design and active aging

    PubMed Central

    Michael, Yvonne L.; Green, Mandy K.; Farquhar, Stephanie A.

    2011-01-01

    This qualitative analysis of focus groups describes how neighborhood design encourages active aging. Nine focus groups were conducted in 2002 and 2003 with residents (N = 60) aged 55 and over living in Portland, OR, USA. Content analysis revealed that local shopping and services, traffic and pedestrian infrastructure, neighborhood attractiveness, and public transportation influence activity among older adults. This information will be useful for making policy recommendations relating to land use planning and transportation, to assist in senior-friendly developments and neighborhood improvements, and to design effective senior health interventions with an emphasis on neighborhood design influences. PMID:16159710

  3. Putting Activism in Its Place: The Neighborhood Context of Participation in Neighborhood-Focused Activism

    PubMed Central

    Gilster, Megan E.

    2012-01-01

    Neighborhood-focused activism is one way residents enact their vision for their community. This study examines the neighborhood socioeconomic antecedents of participation in neighborhood-focused activism in a diverse sample of residents of Chicago neighborhoods to test three theories of neighborhood socioeconomic context and participation: 1) affluence affords participation, 2) activism addresses neighborhood needs associated with disadvantage, and 3) socioeconomic inequality creates contention that necessitates participation. Measuring neighborhood socioeconomic status as two unique dimensions, neighborhood affluence and neighborhood disadvantage, and accounting for both individual and neighborhood characteristics, I find support for each theory. Neighborhood socioeconomic context matters for participation, regardless of individual socioeconomic characteristics. Only when these three perspectives are considered jointly can they fully capture the socioeconomic context of participation in neighborhood-focused activism. PMID:24554811

  4. Putting Activism in Its Place: The Neighborhood Context of Participation in Neighborhood-Focused Activism.

    PubMed

    Gilster, Megan E

    2014-02-01

    Neighborhood-focused activism is one way residents enact their vision for their community. This study examines the neighborhood socioeconomic antecedents of participation in neighborhood-focused activism in a diverse sample of residents of Chicago neighborhoods to test three theories of neighborhood socioeconomic context and participation: 1) affluence affords participation, 2) activism addresses neighborhood needs associated with disadvantage, and 3) socioeconomic inequality creates contention that necessitates participation. Measuring neighborhood socioeconomic status as two unique dimensions, neighborhood affluence and neighborhood disadvantage, and accounting for both individual and neighborhood characteristics, I find support for each theory. Neighborhood socioeconomic context matters for participation, regardless of individual socioeconomic characteristics. Only when these three perspectives are considered jointly can they fully capture the socioeconomic context of participation in neighborhood-focused activism. PMID:24554811

  5. A Vessel Active Contour Model for Vascular Segmentation

    PubMed Central

    Chen, Qingli; Wang, Wei; Peng, Yu; Wang, Qingjun; Wu, Zhongke; Zhou, Mingquan

    2014-01-01

    This paper proposes a vessel active contour model based on local intensity weighting and a vessel vector field. Firstly, the energy function we define is evaluated along the evolving curve instead of all image points, and the function value at each point on the curve is based on the interior and exterior weighted means in a local neighborhood of the point, which is good for dealing with the intensity inhomogeneity. Secondly, a vascular vector field derived from a vesselness measure is employed to guide the contour to evolve along the vessel central skeleton into thin and weak vessels. Thirdly, an automatic initialization method that makes the model converge rapidly is developed, and it avoids repeated trails in conventional local region active contour models. Finally, a speed-up strategy is implemented by labeling the steadily evolved points, and it avoids the repeated computation of these points in the subsequent iterations. Experiments using synthetic and real vessel images validate the proposed model. Comparisons with the localized active contour model, local binary fitting model, and vascular active contour model show that the proposed model is more accurate, efficient, and suitable for extraction of the vessel tree from different medical images. PMID:25101262

  6. A vessel active contour model for vascular segmentation.

    PubMed

    Tian, Yun; Chen, Qingli; Wang, Wei; Peng, Yu; Wang, Qingjun; Duan, Fuqing; Wu, Zhongke; Zhou, Mingquan

    2014-01-01

    This paper proposes a vessel active contour model based on local intensity weighting and a vessel vector field. Firstly, the energy function we define is evaluated along the evolving curve instead of all image points, and the function value at each point on the curve is based on the interior and exterior weighted means in a local neighborhood of the point, which is good for dealing with the intensity inhomogeneity. Secondly, a vascular vector field derived from a vesselness measure is employed to guide the contour to evolve along the vessel central skeleton into thin and weak vessels. Thirdly, an automatic initialization method that makes the model converge rapidly is developed, and it avoids repeated trails in conventional local region active contour models. Finally, a speed-up strategy is implemented by labeling the steadily evolved points, and it avoids the repeated computation of these points in the subsequent iterations. Experiments using synthetic and real vessel images validate the proposed model. Comparisons with the localized active contour model, local binary fitting model, and vascular active contour model show that the proposed model is more accurate, efficient, and suitable for extraction of the vessel tree from different medical images. PMID:25101262

  7. Segmentation of intensity inhomogeneous brain MR images using active contours.

    PubMed

    Akram, Farhan; Kim, Jeong Heon; Lim, Han Ul; Choi, Kwang Nam

    2014-01-01

    Segmentation of intensity inhomogeneous regions is a well-known problem in image analysis applications. This paper presents a region-based active contour method for image segmentation, which properly works in the context of intensity inhomogeneity problem. The proposed region-based active contour method embeds both region and gradient information unlike traditional methods. It contains mainly two terms, area and length, in which the area term practices a new region-based signed pressure force (SPF) function, which utilizes mean values from a certain neighborhood using the local binary fitted (LBF) energy model. In turn, the length term uses gradient information. The novelty of our method is to locally compute new SPF function, which uses local mean values and is able to detect boundaries of the homogenous regions. Finally, a truncated Gaussian kernel is used to regularize the level set function, which not only regularizes it but also removes the need of computationally expensive reinitialization. The proposed method targets the segmentation problem of intensity inhomogeneous images and reduces the time complexity among locally computed active contour methods. The experimental results show that the proposed method yields better segmentation result as well as less time complexity compared with the state-of-the-art active contour methods. PMID:25143780

  8. Hyperspectral image segmentation using active contours

    NASA Astrophysics Data System (ADS)

    Lee, Cheolha P.; Snyder, Wesley E.

    2004-08-01

    Multispectral or hyperspectral image processing has been studied as a possible approach to automatic target recognition (ATR). Hundreds of spectral bands may provide high data redundancy, compensating the low contrast in medium wavelength infrared (MWIR) and long wavelength infrared (LWIR) images. Thus, the combination of spectral (image intensity) and spatial (geometric feature) information analysis could produce a substantial improvement. Active contours provide segments with continuous boundaries, while edge detectors based on local filtering often provide discontinuous boundaries. The segmentation by active contours depends on geometric feature of the object as well as image intensity. However, the application of active contours to multispectral images has been limited to the cases of simply textured images with low number of frames. This paper presents a supervised active contour model, which is applicable to vector-valued images with non-homogeneous regions and high number of frames. In the training stage, histogram models of target classes are estimated from sample vector-pixels. In the test stage, contours are evolved based on two different metrics: the histogram models of the corresponding segments and the histogram models estimated from sample target vector-pixels. The proposed segmentation method integrates segmentation and model-based pattern matching using supervised segmentation and multi-phase active contour model, while traditional methods apply pattern matching only after the segmentation. The proposed algorithm is implemented with both synthetic and real multispectral images, and shows desirable segmentation and classification results even in images with non-homogeneous regions.

  9. Vascular active contour for vessel tree segmentation.

    PubMed

    Shang, Yanfeng; Deklerck, Rudi; Nyssen, Edgard; Markova, Aneta; de Mey, Johan; Yang, Xin; Sun, Kun

    2011-04-01

    In this paper, a novel active contour model is proposed for vessel tree segmentation. First, we introduce a region competition-based active contour model exploiting the gaussian mixture model, which mainly segments thick vessels. Second, we define a vascular vector field to evolve the active contour along its center line into the thin and weak vessels. The vector field is derived from the eigenanalysis of the Hessian matrix of the image intensity in a multiscale framework. Finally, a dual curvature strategy, which uses a vesselness measure-dependent function selecting between a minimal principal curvature and a mean curvature criterion, is added to smoothen the surface of the vessel without changing its shape. The developed model is used to extract the liver and lung vessel tree as well as the coronary artery from high-resolution volumetric computed tomography images. Comparisons are made with several classical active contour models and manual extraction. The experiments show that our model is more accurate and robust than these classical models and is, therefore, more suited for automatic vessel tree extraction. PMID:21138795

  10. Localizing Region-Based Active Contours

    PubMed Central

    Lankton, Shawn; Tannenbaum, Allen

    2009-01-01

    In this paper, we propose a natural framework that allows any region-based segmentation energy to be re-formulated in a local way. We consider local rather than global image statistics and evolve a contour based on local information. Localized contours are capable of segmenting objects with heterogeneous feature profiles that would be difficult to capture correctly using a standard global method. The presented technique is versatile enough to be used with any global region-based active contour energy and instill in it the benefits of localization. We describe this framework and demonstrate the localization of three well-known energies in order to illustrate how our framework can be applied to any energy. We then compare each localized energy to its global counterpart to show the improvements that can be achieved. Next, an in-depth study of the behaviors of these energies in response to the degree of localization is given. Finally, we show results on challenging images to illustrate the robust and accurate segmentations that are possible with this new class of active contour models. PMID:18854247

  11. Active contour based segmentation of resected livers in CT images

    NASA Astrophysics Data System (ADS)

    Oelmann, Simon; Oyarzun Laura, Cristina; Drechsler, Klaus; Wesarg, Stefan

    2015-03-01

    The majority of state of the art segmentation algorithms are able to give proper results in healthy organs but not in pathological ones. However, many clinical applications require an accurate segmentation of pathological organs. The determination of the target boundaries for radiotherapy or liver volumetry calculations are examples of this. Volumetry measurements are of special interest after tumor resection for follow up of liver regrow. The segmentation of resected livers presents additional challenges that were not addressed by state of the art algorithms. This paper presents a snakes based algorithm specially developed for the segmentation of resected livers. The algorithm is enhanced with a novel dynamic smoothing technique that allows the active contour to propagate with different speeds depending on the intensities visible in its neighborhood. The algorithm is evaluated in 6 clinical CT images as well as 18 artificial datasets generated from additional clinical CT images.

  12. Neighborhood context and immigrant children's physical activity.

    PubMed

    Brewer, Mackenzie; Kimbro, Rachel Tolbert

    2014-09-01

    Physical activity is an important determinant of obesity and overall health for children, but significant race/ethnic and nativity disparities exist in the amount of physical activity that children receive, with immigrant children particularly at risk for low levels of physical activity. In this paper, we examine and compare patterns in physical activity levels for young children of U.S.-born and immigrant mothers from seven race/ethnic and nativity groups, and test whether physical activity is associated with subjective (parent-reported) and objective (U.S. Census) neighborhood measures. The neighborhood measures include parental-reported perceptions of safety and physical and social disorder and objectively defined neighborhood socioeconomic disadvantage and immigrant concentration. Using restricted, geo-coded Early Childhood Longitudinal Study-Kindergarten (ECLS-K) data (N = 17,510) from 1998 to 1999 linked with U.S. Census 2000 data for the children's neighborhoods, we utilize zero-inflated Poisson (ZIP) models to predict the odds of physical inactivity and expected days of physical activity for kindergarten-aged children. Across both outcomes, foreign-born children have lower levels of physical activity compared to U.S.-born white children. This disparity is not attenuated by a child's socioeconomic, family, or neighborhood characteristics. Physical and social disorder is associated with higher odds of physical inactivity, while perceptions of neighborhood safety are associated with increased expected days of physical activity, but not with inactivity. Immigrant concentration is negatively associated with both physical activity outcomes, but its impact on the probability of physical inactivity differs by the child's race/ethnic and nativity group, such that it is particularly detrimental for U.S.-born white children's physical activity. Research interested in improving the physical activity patterns of minority and second-generation immigrant children should

  13. Image Segmentation With Cage Active Contours.

    PubMed

    Garrido, Lluís; Guerrieri, Marité; Igual, Laura

    2015-12-01

    In this paper, we present a framework for image segmentation based on parametrized active contours. The evolving contour is parametrized according to a reduced set of control points that form a closed polygon and have a clear visual interpretation. The parametrization, called mean value coordinates, stems from the techniques used in computer graphics to animate virtual models. Our framework allows to easily formulate region-based energies to segment an image. In particular, we present three different local region-based energy terms: 1) the mean model; 2) the Gaussian model; 3) and the histogram model. We show the behavior of our method on synthetic and real images and compare the performance with state-of-the-art level set methods. PMID:26316128

  14. Human body contour data based activity recognition.

    PubMed

    Myagmarbayar, Nergui; Yuki, Yoshida; Imamoglu, Nevrez; Gonzalez, Jose; Otake, Mihoko; Yu, Wenwei

    2013-01-01

    This research work is aimed to develop autonomous bio-monitoring mobile robots, which are capable of tracking and measuring patients' motions, recognizing the patients' behavior based on observation data, and providing calling for medical personnel in emergency situations in home environment. The robots to be developed will bring about cost-effective, safe and easier at-home rehabilitation to most motor-function impaired patients (MIPs). In our previous research, a full framework was established towards this research goal. In this research, we aimed at improving the human activity recognition by using contour data of the tracked human subject extracted from the depth images as the signal source, instead of the lower limb joint angle data used in the previous research, which are more likely to be affected by the motion of the robot and human subjects. Several geometric parameters, such as, the ratio of height to weight of the tracked human subject, and distance (pixels) between centroid points of upper and lower parts of human body, were calculated from the contour data, and used as the features for the activity recognition. A Hidden Markov Model (HMM) is employed to classify different human activities from the features. Experimental results showed that the human activity recognition could be achieved with a high correct rate. PMID:24111015

  15. Neighborhood walkability, physical activity, and walking behavior: the Swedish Neighborhood and Physical Activity (SNAP) study.

    PubMed

    Sundquist, Kristina; Eriksson, Ulf; Kawakami, Naomi; Skog, Lars; Ohlsson, Henrik; Arvidsson, Daniel

    2011-04-01

    More knowledge concerning the association between physical activity and objectively measured attributes of the built environment is needed. Previous studies on the association between objectively measured neighborhood walkability, physical activity, and walking have been conducted in the U.S. or Australia and research findings are available from only one country in Europe - Belgium. The first aim of this Swedish study of 2269 adults was to examine the associations between neighborhood walkability and walking for active transportation or leisure, and moderate-to-vigorous physical activity (MVPA) and whether these hypothesized associations are moderated by age, gender, income, marital status and neighborhood-level socioeconomic status. The second aim was to determine how much of the total variance of the walking and physical activity outcomes can be attributed to neighborhood-level differences. Neighborhood walkability was objectively measured by GIS methods. An index consisting of residential density, street connectivity, and land use mix was constructed to define 32 highly and less walkable neighborhoods in Stockholm City. MVPA was measured objectively during 7 days with an accelerometer and walking was assessed using the validated International Physical Activity Questionnaire (IPAQ). Multilevel linear as well as logistic models (mixed-effects, mixed-distribution models) were used in the analysis. The statistically significant and "adjusted" results for individuals living in highly walkable neighborhoods, as compared to those living in less walkable neighborhoods, were: (1) 77% and 28% higher odds for walking for active transportation and walking for leisure, respectively, (2) 50 min more walking for active transportation/week, and (3) 3.1 min more MVPA/day. The proportion of the total variance at the neighborhood level was low and ranged between 0.0% and 2.1% in the adjusted models. The findings of the present study stress that future policies concerning the

  16. Prostate contours delineation using interactive directional active contours model and parametric shape prior model.

    PubMed

    Derraz, Foued; Forzy, Gérard; Delebarre, Arnaud; Taleb-Ahmed, Abdelmalik; Oussalah, Mourad; Peyrodie, Laurent; Verclytte, Sebastien

    2015-11-01

    Prostate contours delineation on Magnetic Resonance (MR) images is a challenging and important task in medical imaging with applications of guiding biopsy, surgery and therapy. While a fully automated method is highly desired for this application, it can be a very difficult task due to the structure and surrounding tissues of the prostate gland. Traditional active contours-based delineation algorithms are typically quite successful for piecewise constant images. Nevertheless, when MR images have diffuse edges or multiple similar objects (e.g. bladder close to prostate) within close proximity, such approaches have proven to be unsuccessful. In order to mitigate these problems, we proposed a new framework for bi-stage contours delineation algorithm based on directional active contours (DAC) incorporating prior knowledge of the prostate shape. We first explicitly addressed the prostate contour delineation problem based on fast globally DAC that incorporates both statistical and parametric shape prior model. In doing so, we were able to exploit the global aspects of contour delineation problem by incorporating a user feedback in contours delineation process where it is shown that only a small amount of user input can sometimes resolve ambiguous scenarios raised by DAC. In addition, once the prostate contours have been delineated, a cost functional is designed to incorporate both user feedback interaction and the parametric shape prior model. Using data from publicly available prostate MR datasets, which includes several challenging clinical datasets, we highlighted the effectiveness and the capability of the proposed algorithm. Besides, the algorithm has been compared with several state-of-the-art methods. PMID:26009857

  17. Multi-object geodesic active contours (MOGAC).

    PubMed

    Lucas, Blake C; Kazhdan, Michael; Taylor, Russell H

    2012-01-01

    An emerging topic is to build image segmentation systems that can segment hundreds to thousands of objects (i.e. cell segmentation\\tracking, full brain parcellation, full body segmentation, etc.). Multi-object Level Set Methods (MLSM) perform this task with the benefit of sub-pixel precision. However, current implementations of MLSM are not as computationally or memory efficient as their region growing and graph cut counterparts which lack sub-pixel precision. To address this performance gap, we present a novel parallel implementation of MLSM that leverages the sparse properties of the algorithm to minimize its memory footprint for multiple objects. The new method, Multi-Object Geodesic Active Contours (MOGAC), can represent N objects with just two functions: a label mask image and unsigned distance field. The time complexity of the algorithm is shown to be O((M (power)d)/P) for M (power)d pixels and P processing units in dimension d = {2,3}, independent of the number of objects. Results are presented for 2D and 3D image segmentation problems. PMID:23286074

  18. Youth physical activity opportunities in lower and higher income neighborhoods.

    PubMed

    Suminski, Richard Robert; Ding, Ding; Lee, Rebecca; May, Linda; Tota, Tonya; Dinius, David

    2011-08-01

    The presence of youth physical activity opportunities is one of the strongest environmental correlates of youth physical activity. More detailed information about such opportunities is needed to maximize their contributions to physical activity promotion especially in under resourced, lower income areas. The objectives of this study were to construct a comprehensive profile of youth physical activity opportunities and contrast profile characteristics between lower and higher income neighborhoods. Youth physical activity opportunities in eight lower (median household income <$36,000) and eight higher (>$36,000) income neighborhoods were identified and described using interviews, neighborhood tours, site visits, and systematic searches of various sources (e.g., Internet). Lower income neighborhoods had a greater number of locations offering youth physical activity opportunities but similar quantities of amenities. Lower income neighborhoods had more faith-based locations and court, trail/path, event, and water-type amenities. Higher income neighborhoods had significantly more for-profit businesses offering youth physical activity opportunities. Funding for youth physical activity opportunities in lower income neighborhoods was more likely to come from donations and government revenue (e.g., taxes), whereas the majority of youth physical activity opportunities in the higher income neighborhoods were supported by for-profit business revenue. Differences between lower and higher income neighborhoods in the type and amenities of youth physical activity opportunities may be driven by funding sources. Attention to these differences could help create more effective and efficient strategies for promoting physical activity among youth. PMID:21494895

  19. Activation of proto-oncogenes by disruption of chromosome neighborhoods.

    PubMed

    Hnisz, Denes; Weintraub, Abraham S; Day, Daniel S; Valton, Anne-Laure; Bak, Rasmus O; Li, Charles H; Goldmann, Johanna; Lajoie, Bryan R; Fan, Zi Peng; Sigova, Alla A; Reddy, Jessica; Borges-Rivera, Diego; Lee, Tong Ihn; Jaenisch, Rudolf; Porteus, Matthew H; Dekker, Job; Young, Richard A

    2016-03-25

    Oncogenes are activated through well-known chromosomal alterations such as gene fusion, translocation, and focal amplification. In light of recent evidence that the control of key genes depends on chromosome structures called insulated neighborhoods, we investigated whether proto-oncogenes occur within these structures and whether oncogene activation can occur via disruption of insulated neighborhood boundaries in cancer cells. We mapped insulated neighborhoods in T cell acute lymphoblastic leukemia (T-ALL) and found that tumor cell genomes contain recurrent microdeletions that eliminate the boundary sites of insulated neighborhoods containing prominent T-ALL proto-oncogenes. Perturbation of such boundaries in nonmalignant cells was sufficient to activate proto-oncogenes. Mutations affecting chromosome neighborhood boundaries were found in many types of cancer. Thus, oncogene activation can occur via genetic alterations that disrupt insulated neighborhoods in malignant cells. PMID:26940867

  20. Segmentation and Tracking of Cytoskeletal Filaments Using Open Active Contours

    PubMed Central

    Smith, Matthew B.; Li, Hongsheng; Shen, Tian; Huang, Xiaolei; Yusuf, Eddy; Vavylonis, Dimitrios

    2010-01-01

    We use open active contours to quantify cytoskeletal structures imaged by fluorescence microscopy in two and three dimensions. We developed an interactive software tool for segmentation, tracking, and visualization of individual fibers. Open active contours are parametric curves that deform to minimize the sum of an external energy derived from the image and an internal bending and stretching energy. The external energy generates (i) forces that attract the contour toward the central bright line of a filament in the image, and (ii) forces that stretch the active contour toward the ends of bright ridges. Images of simulated semiflexible polymers with known bending and torsional rigidity are analyzed to validate the method. We apply our methods to quantify the conformations and dynamics of actin in two examples: actin filaments imaged by TIRF microscopy in vitro, and actin cables in fission yeast imaged by spinning disk confocal microscopy. PMID:20814909

  1. Multiresolution active contour model applied on lung and colon images

    NASA Astrophysics Data System (ADS)

    Dehmeshki, Jamshid; Siddique, Musib; Wong, Wing; Chis Ster, Irina

    2004-05-01

    This paper deploys a wavelet based scale-space approach to extract the boundary of the object of interest in medical CT images. The classical approach of the active contour models consists of starting with an initial contour, to deform it under the action of some forces attracting the contour towards the edges by means of a set of forces. The mathematical model involves in the minimisation of an objective function called energy functional, which depends on the geometry of the contour as well as of the image characteristics. Various strategies could be used for the formulation of the energy functional and its optimisation. In this study, a wavelet based scale-space approach has been adopted. The coarsest scale is able to enlarge the capture region surrounding an object and avoids the trapping of contour into weak edges. The finer scales are used to refine the contour as close as possible to the boundary of the object. An adaptive scale coefficient for the balloon energy has been introduced. Four levels of resolution have been applied in order to get reproducibility of the contour despite poor different initialisations. The scheme has been applied to segment the regions of interest in CT lung and colon images. The result has been shown to be accurate and reproducible for the cases containing fat, holes and other small high intensity objects inside lung nodules as well as colon polyps.

  2. Children's Objective Physical Activity by Location: Why the Neighborhood Matters

    PubMed Central

    Kneeshaw-Price, Stephanie; Saelens, Brian; Sallis, James; Glanz, Karen; Frank, Lawrence; Kerr, Jacqueline; Hannon, Peggy; Grembowski, David; Chan, KC Gary; Cain, Kelli

    2014-01-01

    Knowledge of where children are active may lead to more informed policies about how and where to intervene and improve physical activity. This study examined where children aged 6–11 were physically active using time-stamped accelerometer data and parent-reported place logs and assessed the association of physical-activity location variation with demographic factors. Children spent most time and did most physical activity at home and school. Although neighborhood time was limited, this time was more proportionally active than time in other locations (e.g., active 42.1% of time in neighborhood vs. 18.1% of time at home). Children with any neighborhood-based physical activity had higher average total physical activity. Policies and environments that encourage children to spend time outdoors in their neighborhoods could result in higher overall physical activity. PMID:23877357

  3. Iterative weighted average diffusion as a novel external force in the active contour model

    NASA Astrophysics Data System (ADS)

    Mirov, Ilya S.; Nakhmani, Arie

    2016-03-01

    The active contour model has good performance in boundary extraction for medical images; particularly, Gradient Vector Flow (GVF) active contour model shows good performance at concavity convergence and insensitivity to initialization, yet it is susceptible to edge leaking, deep and narrow concavities, and has some issues handling noisy images. This paper proposes a novel external force, called Iterative Weighted Average Diffusion (IWAD), which used in tandem with parametric active contours, provides superior performance in images with high values of concavity. The image gradient is first turned into an edge image, smoothed, and modified with enhanced corner detection, then the IWAD algorithm diffuses the force at a given pixel based on its 3x3 pixel neighborhood. A forgetting factor, φ, is employed to ensure that forces being spread away from the boundary of the image will attenuate. The experimental results show better behavior in high curvature regions, faster convergence, and less edge leaking than GVF when both are compared to expert manual segmentation of the images.

  4. An Investigation of Implicit Active Contours for Scientific Image Segmentation

    SciTech Connect

    Weeratunga, S K; Kamath, C

    2003-10-29

    The use of partial differential equations in image processing has become an active area of research in the last few years. In particular, active contours are being used for image segmentation, either explicitly as snakes, or implicitly through the level set approach. In this paper, we consider the use of the implicit active contour approach for segmenting scientific images of pollen grains obtained using a scanning electron microscope. Our goal is to better understand the pros and cons of these techniques and to compare them with the traditional approaches such as the Canny and SUSAN edge detectors. The preliminary results of our study show that the level set method is computationally expensive and requires the setting of several different parameters. However, it results in closed contours, which may be useful in separating objects from the background in an image.

  5. Social Disorganization, Drug Market Activity, and Neighborhood Violent Crime.

    PubMed

    Martínez, Ramiro; Rosenfeld, Richard; Mares, Dennis

    2008-01-01

    Although illicit drug activity occurs within local communities, past quantitative research on drug markets and violent crime in the United States has been conducted mainly at the city level. The authors use neighborhood-level data from the city of Miami to test hypotheses regarding the effect of drug activity and traditional indicators of social disorganization on rates of aggravated assault and robbery. The results show that drug activity has robust effects on violent crime that are independent of other disorganization indicators. The authors also find that drug activity is concentrated in neighborhoods with low rates of immigration, less linguistic isolation and ethnic heterogeneity, and where nondrug accidental deaths are prevalent. The authors find no independent effect of neighborhood racial composition on drug activity or violent crime. The results suggest that future neighborhood-level research on social disorganization and violent crime should devote explicit attention to the disorganizing and violence-producing effects of illicit drug activity. PMID:19655037

  6. Social Disorganization, Drug Market Activity, and Neighborhood Violent Crime

    PubMed Central

    Martínez, Ramiro; Rosenfeld, Richard; Mares, Dennis

    2009-01-01

    Although illicit drug activity occurs within local communities, past quantitative research on drug markets and violent crime in the United States has been conducted mainly at the city level. The authors use neighborhood-level data from the city of Miami to test hypotheses regarding the effect of drug activity and traditional indicators of social disorganization on rates of aggravated assault and robbery. The results show that drug activity has robust effects on violent crime that are independent of other disorganization indicators. The authors also find that drug activity is concentrated in neighborhoods with low rates of immigration, less linguistic isolation and ethnic heterogeneity, and where nondrug accidental deaths are prevalent. The authors find no independent effect of neighborhood racial composition on drug activity or violent crime. The results suggest that future neighborhood-level research on social disorganization and violent crime should devote explicit attention to the disorganizing and violence-producing effects of illicit drug activity. PMID:19655037

  7. Research of Active Contour Model in Aerial Images

    NASA Astrophysics Data System (ADS)

    Kun, Wang; Li, Guo

    With the development of computer and aviation technology, the aerial image is facing an important issue is how to automate, including aerial images of the automatic extraction of the target. In this paper, the issue of aerial images to study the active contour model is introduced, that is, Snake model, to achieve the target aerial image of the semi-automatic contour extraction method. Snake model used the unique characteristic of the energy minimization, carried out on the image contour extraction, to obtain a clear, consistent and accurate image contour. The model is defined through the energy minimization of the function, given in the initial position of artificial circumstances, through the iterative calculation of Snake model will eventually form the minimum energy function has been described in the outline of the target partition. The results indicate that Snake model for aerial images of the edge contour extraction, verification, concluded that the Snake-based edge detection methods could be more objectively and accurately extract the edge of the outline of aerial images.

  8. Automated optic disk boundary detection by modified active contour model.

    PubMed

    Xu, Juan; Chutatape, Opas; Chew, Paul

    2007-03-01

    This paper presents a novel deformable-model-based algorithm for fully automated detection of optic disk boundary in fundus images. The proposed method improves and extends the original snake (deforming-only technique) in two aspects: clustering and smoothing update. The contour points are first self-separated into edge-point group or uncertain-point group by clustering after each deformation, and these contour points are then updated by different criteria based on different groups. The updating process combines both the local and global information of the contour to achieve the balance of contour stability and accuracy. The modifications make the proposed algorithm more accurate and robust to blood vessel occlusions, noises, ill-defined edges and fuzzy contour shapes. The comparative results show that the proposed method can estimate the disk boundaries of 100 test images closer to the groundtruth, as measured by mean distance to closest point (MDCP) <3 pixels, with the better success rate when compared to those obtained by gradient vector flow snake (GVF-snake) and modified active shape models (ASM). PMID:17355059

  9. Active contours for localizing polyps in colonoscopic NBI image data

    NASA Astrophysics Data System (ADS)

    Breier, Matthias; Gross, Sebastian; Behrens, Alexander; Stehle, Thomas; Aach, Til

    2011-03-01

    Colon cancer is the third most common type of cancer in the United States of America. Every year about 140,000 people are newly diagnosed with colon cancer. Early detection is crucial for a successful therapy. The standard screening procedure is called colonoscopy. Using this endoscopic examination physicians can find colon polyps and remove them if necessary. Adenomatous colon polyps are deemed a preliminary stage of colon cancer. The removal of a polyp, though, can lead to complications like severe bleedings or colon perforation. Thus, only polyps diagnosed as adenomatous should be removed. To decide whether a polyp is adenomatous the polyp's surface structure including vascular patterns has to be inspected. Narrow-Band imaging (NBI) is a new tool to improve visibility of vascular patterns of the polyps. The first step for an automatic polyp classification system is the localization of the polyp. We investigate active contours for the localization of colon polyps in NBI image data. The shape of polyps, though roughly approximated by an elliptic form, is highly variable. Active contours offer the flexibility to adapt to polyp variation well. To avoid clustering of contour polygon points we propose the application of active rays. The quality of the results was evaluated based on manually segmented polyps as ground truth data. The results were compared to a template matching approach and to the Generalized Hough Transform. Active contours are superior to the Hough transform and perform equally well as the template matching approach.

  10. Multiple LREK active contours for knee meniscus ultrasound image segmentation.

    PubMed

    Faisal, Amir; Ng, Siew-Cheok; Goh, Siew-Li; George, John; Supriyanto, Eko; Lai, Khin W

    2015-10-01

    Quantification of knee meniscus degeneration and displacement in an ultrasound image requires simultaneous segmentation of femoral condyle, meniscus, and tibial plateau in order to determine the area and the position of the meniscus. In this paper, we present an active contour for image segmentation that uses scalable local regional information on expandable kernel (LREK). It includes using a strategy to adapt the size of a local window in order to avoid being confined locally in a homogeneous region during the segmentation process. We also provide a multiple active contours framework called multiple LREK (MLREK) to deal with multiple object segmentation without merging and overlapping between the neighboring contours in the shared boundaries of separate regions. We compare its performance to other existing active contour models and show an improvement offered by our model. We then investigate the choice of various parameters in the proposed framework in response to the segmentation outcome. Dice coefficient and Hausdorff distance measures over a set of real knee meniscus ultrasound images indicate a potential application of MLREK for assessment of knee meniscus degeneration and displacement. PMID:25910057

  11. Neighborhood Design and Perceptions: Relationship with Active Commuting

    PubMed Central

    Voorhees, Carolyn C.; Ashwood, J. Scott; Evenson, Kelly R.; Sirard, John R.; Rung, Ariane L.; Dowda, Marsha; McKenzie, Thomas L.

    2010-01-01

    Purpose Walking to and from school contributes to total physical activity levels. This study investigated whether perceived and actual neighborhood features were associated with walking to or from school among adolescent girls. Methods A sample of geographically diverse 8th grade girls (N=890) from the Trial for Activity in Adolescent Girls (TAAG) study living within 1.5 miles of their middle school were recruited. Participants completed a self-administered survey on their neighborhood and walking behavior. Geographic information system (GIS) data were used to assess objective neighborhood features. Nested multivariable logistic regression analyses were conducted to determine the contribution of perceived and objective measures of walking to or from school. Results Fifty-six percent (N=500) of the girls walked to or from school at least one day of the week. White (42%) girls walked more frequently than Hispanic (25%) and African American (21%) girls. Girls were nearly twice as likely to walk to or from school if they perceived their neighborhoods as safe and perceived they had places they liked to walk, controlling for other potential confounders. Additionally, girls who lived closer to school, had more active destinations in their neighborhood, and smaller sized blocks were more likely to walk to or from school than those who did not. Conclusion Safety, land use, and school location issues need to be considered together when designing interventions to increase walking to and from school. PMID:20019628

  12. Neighborhood Rhythms and the Social Activities of Adolescent Mothers.

    ERIC Educational Resources Information Center

    Burton, Linda M.; Graham, Joan E.

    1998-01-01

    A five-year longitudinal ethnographic study explores the relationship between the temporal organization of neighborhood activities and the social engagements of urban African American teen mothers. Found that courting activities occurred during the morning, baby parading during the afternoon-evening, with teen mothers avoiding the illicit drug…

  13. Do Neighborhoods Make People Active, or Do People Make Active Neighborhoods? Evidence from a Planned Community in Austin, Texas

    PubMed Central

    Heeren, Timothy; DeJong, William; Dumith, Samuel C.; Kohl, Harold W.

    2013-01-01

    Introduction Whether patterns of physical activity in different communities can be attributed to the built environment or instead reflect self-selection is not well understood. The objective of this study was to examine neighborhood preferences and behavior-specific physical activity among residents who moved to a new urbanist-designed community. Methods We used data from a 2009 survey (n = 424) that was designed and administered to evaluate neighborhood preferences and behavior-specific physical activity before and after residents moved. Data were grouped and stratified by pre-move physical activity levels into low-, middle-, and high-activity groups. We used Student’s paired sample t test and Wilcoxon signed-rank test to compare pre- and post-move scores and used an analysis of variance to compare mean changes as a function of pre-move physical activity level. Results After moving, the high-activity group continued to be significantly more active than the middle- and low-activity groups (P < .001). However, we saw the biggest increase in pre- to post-move total physical activity in the low-activity group (mean increase, 176.3 min/wk) compared with the middle- (mean increase, 69.5 min/wk) and high-activity groups (mean decrease, 67.9 min/wk). All 3 groups had significant increases in walking inside the neighborhood for recreation. The preferred neighborhood features with the most significant pre- to post-move change scores were those associated with greater walkability. Conclusion This study supports the role the environment plays in physical activity. These data suggest that moving to an activity-friendly neighborhood can positively affect physical activity levels, particularly among residents who had previously been least active. PMID:23786909

  14. Children’s physical activity and parents’ perception of the neighborhood environment: neighborhood impact on kids study

    PubMed Central

    2013-01-01

    Background Physical activity is important to children’s physical health and well-being. Many factors contribute to children’s physical activity, and the built environment has garnered considerable interest recently, as many young children spend much of their time in and around their immediate neighborhood. Few studies have identified correlates of children’s activity in specific locations. This study examined associations between parent report of their home neighborhood environment and children’s overall and location-specific physical activity. Methods Parents and children ages 6 to 11 (n=724), living in neighborhoods identified through objective built environment factors as high or low in physical activity environments, were recruited from Seattle and San Diego metropolitan areas, 2007–2009. Parents completed a survey about their child’s activity and perceptions of home neighborhood environmental attributes. Children wore an accelerometer for 7 days. Multivariate regression models explored perceived environment correlates of parent-reported child’s recreational physical activity in their neighborhood, in parks, and in general, as well as accelerometry-based moderate-to-vigorous activity (MVPA) minutes. Results Parent-reported proximity to play areas correlated positively with both accelerometery MVPA and parent-reported total child physical activity. Lower street connectivity and higher neighborhood aesthetics correlated with higher reported child activity in the neighborhood, while reported safety from crime and walk and cycle facilities correlated positively with reported child activity in public recreation spaces. Conclusions Different aspects of parent’s perceptions of the neighborhood environment appear to correlate with different aspects of children’s activity. However, prioritizing closer proximity to safe play areas may best improve children’s physical activity and, in turn, reduce their risk of obesity and associated chronic diseases

  15. Pupil segmentation using active contour with shape prior

    NASA Astrophysics Data System (ADS)

    Ukpai, Charles O.; Dlay, Satnam S.; Woo, Wai L.

    2015-03-01

    Iris segmentation is the process of defining the valid part of the eye image used for further processing (feature extraction, matching and decision making). Segmentation of the iris mostly starts with pupil boundary segmentation. Most pupil segmentation techniques are based on the assumption that the pupil is circular shape. In this paper, we propose a new pupil segmentation technique which combines shape, location and spatial information for accurate and efficient segmentation of the pupil. Initially, the pupil's position and radius is estimated using a statistical approach and circular Hough transform. In order to segment the irregular boundary of the pupil, an active contour model is initialized close to the estimated boundary using information from the first step and segmentation is achieved using energy minimization based active contour. Pre-processing and post-processing were carried out to remove noise and occlusions respectively. Experimental results on CASIA V1.0 and 4.0 shows that the proposed method is highly effective at segmenting irregular boundaries of the pupil.

  16. Implicit active contours for automatic brachytherapy seed segmentation in fluoroscopy

    NASA Astrophysics Data System (ADS)

    Moult, Eric; Burdette, Clif; Song, Danny; Fichtinger, Gabor; Fallavollita, Pascal

    2012-02-01

    Motivation: In prostate brachytherapy, intra-operative dosimetry would be ideal to allow for rapid evaluation of the implant quality while the patient is still in the treatment position. Such a mechanism, however, requires 3-D visualization of the currently deposited seeds relative to the prostate. Thus, accurate, robust, and fully-automatic seed segmentation is of critical importance in achieving intra-operative dosimetry. Methodology: Implanted brachytherapy seeds are segmented by utilizing a region-based implicit active contour approach. Overlapping seed clusters are then resolved using a simple yet effective declustering technique. Results: Ground-truth seed coordinates were obtained via a published segmentation technique. A total of 248 clinical C-arm images from 16 patients were used to validate the proposed algorithm resulting in a 98.4% automatic detection rate with a corresponding 2.5% false-positive rate. The overall mean centroid error between the ground-truth and automatic segmentations was measured to be 0.42 pixels, while the mean centroid error for overlapping seed clusters alone was measured to be 0.67 pixels. Conclusion: Based on clinical data evaluation and validation, robust, accurate, and fully-automatic brachytherapy seed segmentation can be achieved through the implicit active contour framework and subsequent seed declustering method.

  17. Fast Virtual Stenting with Active Contour Models in Intracranical Aneurysm

    PubMed Central

    Zhong, Jingru; Long, Yunling; Yan, Huagang; Meng, Qianqian; Zhao, Jing; Zhang, Ying; Yang, Xinjian; Li, Haiyun

    2016-01-01

    Intracranial stents are becoming increasingly a useful option in the treatment of intracranial aneurysms (IAs). Image simulation of the releasing stent configuration together with computational fluid dynamics (CFD) simulation prior to intervention will help surgeons optimize intervention scheme. This paper proposed a fast virtual stenting of IAs based on active contour model (ACM) which was able to virtually release stents within any patient-specific shaped vessel and aneurysm models built on real medical image data. In this method, an initial stent mesh was generated along the centerline of the parent artery without the need for registration between the stent contour and the vessel. Additionally, the diameter of the initial stent volumetric mesh was set to the maximum inscribed sphere diameter of the parent artery to improve the stenting accuracy and save computational cost. At last, a novel criterion for terminating virtual stent expanding that was based on the collision detection of the axis aligned bounding boxes was applied, making the stent expansion free of edge effect. The experiment results of the virtual stenting and the corresponding CFD simulations exhibited the efficacy and accuracy of the ACM based method, which are valuable to intervention scheme selection and therapy plan confirmation. PMID:26876026

  18. Convolutional virtual electric field for image segmentation using active contours.

    PubMed

    Wang, Yuanquan; Zhu, Ce; Zhang, Jiawan; Jian, Yuden

    2014-01-01

    Gradient vector flow (GVF) is an effective external force for active contours; however, it suffers from heavy computation load. The virtual electric field (VEF) model, which can be implemented in real time using fast Fourier transform (FFT), has been proposed later as a remedy for the GVF model. In this work, we present an extension of the VEF model, which is referred to as CONvolutional Virtual Electric Field, CONVEF for short. This proposed CONVEF model takes the VEF model as a convolution operation and employs a modified distance in the convolution kernel. The CONVEF model is also closely related to the vector field convolution (VFC) model. Compared with the GVF, VEF and VFC models, the CONVEF model possesses not only some desirable properties of these models, such as enlarged capture range, u-shape concavity convergence, subject contour convergence and initialization insensitivity, but also some other interesting properties such as G-shape concavity convergence, neighboring objects separation, and noise suppression and simultaneously weak edge preserving. Meanwhile, the CONVEF model can also be implemented in real-time by using FFT. Experimental results illustrate these advantages of the CONVEF model on both synthetic and natural images. PMID:25360586

  19. Application of active contours for photochromic tracer flow extraction.

    PubMed

    Androutsos, D; Trahanias, P E; Venetsanopoulos, A N

    1997-06-01

    This paper addresses the implementation of image processing and computer vision techniques to automate tracer flow extraction in images obtained by the photochromic dye technique. This task is important in modeled arterial blood flow studies. Currently, it is performed via manual application of B-spline curve fitting. However, this is a tedious and error-prone procedure and its results are nonreproducible. In the proposed approach, active contours, snakes, are employed in a new curve-fitting method for tracer flow extraction in photochromic images. An algorithm implementing snakes is introduced to automate extraction. Utilizing correlation matching, the algorithm quickly locates and localizes all flow traces in the images. The feasibility of the method for tracer flow extraction is demonstrated. Moreover, results regarding the automation algorithm are presented showing its accuracy and effectiveness. The proposed approach for tracer flow extraction has potential for real-system application. PMID:9184890

  20. The Neighborhood Energy Balance Equation: Does Neighborhood Food Retail Environment + Physical Activity Environment = Obesity? The CARDIA Study

    PubMed Central

    Boone-Heinonen, Janne; Diez-Roux, Ana V.; Goff, David C.; Loria, Catherine M.; Kiefe, Catarina I.; Popkin, Barry M.; Gordon-Larsen, Penny

    2013-01-01

    Background Recent obesity prevention initiatives focus on healthy neighborhood design, but most research examines neighborhood food retail and physical activity (PA) environments in isolation. We estimated joint, interactive, and cumulative impacts of neighborhood food retail and PA environment characteristics on body mass index (BMI) throughout early adulthood. Methods and Findings We used cohort data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study [n=4,092; Year 7 (24-42 years, 1992-1993) followed over 5 exams through Year 25 (2010-2011); 12,921 person-exam observations], with linked time-varying geographic information system-derived neighborhood environment measures. Using regression with fixed effects for individuals, we modeled time-lagged BMI as a function of food and PA resource density (counts per population) and neighborhood development intensity (a composite density score). We controlled for neighborhood poverty, individual-level sociodemographics, and BMI in the prior exam; and included significant interactions between neighborhood measures and by sex. Using model coefficients, we simulated BMI reductions in response to single and combined neighborhood improvements. Simulated increase in supermarket density (from 25th to 75th percentile) predicted inter-exam reduction in BMI of 0.09 kg/m2 [estimate (95% CI): -0.09 (-0.16, -0.02)]. Increasing commercial PA facility density predicted BMI reductions up to 0.22 kg/m2 in men, with variation across other neighborhood features [estimate (95% CI) range: -0.14 (-0.29, 0.01) to -0.22 (-0.37, -0.08)]. Simultaneous increases in supermarket and commercial PA facility density predicted inter-exam BMI reductions up to 0.31 kg/m2 in men [estimate (95% CI) range: -0.23 (-0.39, -0.06) to -0.31 (-0.47, -0.15)] but not women. Reduced fast food restaurant and convenience store density and increased public PA facility density and neighborhood development intensity did not predict reductions in BMI

  1. Neighborhood Environments and Objectively Measured Physical Activity in 11 Countries

    PubMed Central

    Cerin, Ester; Cain, Kelli L; Conway, Terry L; Dyck, Delfien Van; Hinckson, Erica; Schipperijn, Jasper; Bourdeaudhuij, Ilse De; Owen, Neville; Davey, Rachel C; Hino, Adriano Akira Ferreira; Mitáš, Josef; Orzanco-Garralda, Rosario; Salvo, Deborah; Sarmiento, Olga L; Christiansen, Lars B; Macfarlane, Duncan J; Schofield, Grant; Sallis, James F

    2014-01-01

    Purpose Environmental changes are potentially effective population-level physical activity (PA) promotion strategies. However, robust multi-site evidence to guide international action for developing activity-supportive environments is lacking. We estimated pooled associations of perceived environmental attributes with objectively-measured PA outcomes; between-site differences in such associations; and, the extent to which perceived environmental attributes explain between-site differences in PA. Methods This was a cross-sectional study conducted in 16 cities located in Belgium, Brazil, Colombia, Czech Republic, Denmark, China, Mexico, New Zealand, Spain, United Kingdom, and USA. Participants were 6,968 adults residing in administrative units stratified by socio-economic status and transport-related walkability. Predictors were 10 perceived neighborhood environmental attributes. Outcome measures were accelerometry-assessed weekly minutes of moderate-to-vigorous PA (MVPA) and meeting the PA guidelines for cancer/weight gain prevention (420 min/week of MVPA). Results Most perceived neighborhood attributes were positively associated with the PA outcomes in the pooled, site-adjusted, single-predictor models. Associations were generalizable across geographical locations. Aesthetics and land use mix – access were significant predictors of both PA outcomes in the fully-adjusted models. Environmental attributes accounted for within-site variability in MVPA corresponding to a 3 min/d or 21 min/week standard deviation. Large between-site differences in PA outcomes were observed: 15.9% to 16.8% of these differences were explained by perceived environmental attributes. All neighborhood attributes were associated with between-site differences in the total effects of the perceived environment on PA outcomes. Conclusions Residents’ perceptions of neighborhood attributes that facilitate walking were positively associated with objectively-measured MVPA and meeting the guidelines

  2. 3D Actin Network Centerline Extraction with Multiple Active Contours

    PubMed Central

    Xu, Ting; Vavylonis, Dimitrios; Huang, Xiaolei

    2013-01-01

    Fluorescence microscopy is frequently used to study two and three dimensional network structures formed by cytoskeletal polymer fibers such as actin filaments and actin cables. While these cytoskeletal structures are often dilute enough to allow imaging of individual filaments or bundles of them, quantitative analysis of these images is challenging. To facilitate quantitative, reproducible and objective analysis of the image data, we propose a semi-automated method to extract actin networks and retrieve their topology in 3D. Our method uses multiple Stretching Open Active Contours (SOACs) that are automatically initialized at image intensity ridges and then evolve along the centerlines of filaments in the network. SOACs can merge, stop at junctions, and reconfigure with others to allow smooth crossing at junctions of filaments. The proposed approach is generally applicable to images of curvilinear networks with low SNR. We demonstrate its potential by extracting the centerlines of synthetic meshwork images, actin networks in 2D Total Internal Reflection Fluorescence Microscopy images, and 3D actin cable meshworks of live fission yeast cells imaged by spinning disk confocal microscopy. Quantitative evaluation of the method using synthetic images shows that for images with SNR above 5.0, the average vertex error measured by the distance between our result and ground truth is 1 voxel, and the average Hausdorff distance is below 10 voxels. PMID:24316442

  3. 3D Filament Network Segmentation with Multiple Active Contours

    NASA Astrophysics Data System (ADS)

    Xu, Ting; Vavylonis, Dimitrios; Huang, Xiaolei

    2014-03-01

    Fluorescence microscopy is frequently used to study two and three dimensional network structures formed by cytoskeletal polymer fibers such as actin filaments and microtubules. While these cytoskeletal structures are often dilute enough to allow imaging of individual filaments or bundles of them, quantitative analysis of these images is challenging. To facilitate quantitative, reproducible and objective analysis of the image data, we developed a semi-automated method to extract actin networks and retrieve their topology in 3D. Our method uses multiple Stretching Open Active Contours (SOACs) that are automatically initialized at image intensity ridges and then evolve along the centerlines of filaments in the network. SOACs can merge, stop at junctions, and reconfigure with others to allow smooth crossing at junctions of filaments. The proposed approach is generally applicable to images of curvilinear networks with low SNR. We demonstrate its potential by extracting the centerlines of synthetic meshwork images, actin networks in 2D TIRF Microscopy images, and 3D actin cable meshworks of live fission yeast cells imaged by spinning disk confocal microscopy.

  4. Lung segmentation from HRCT using united geometric active contours

    NASA Astrophysics Data System (ADS)

    Liu, Junwei; Li, Chuanfu; Xiong, Jin; Feng, Huanqing

    2007-12-01

    Accurate lung segmentation from high resolution CT images is a challenging task due to various detail tracheal structures, missing boundary segments and complex lung anatomy. One popular method is based on gray-level threshold, however its results are usually rough. A united geometric active contours model based on level set is proposed for lung segmentation in this paper. Particularly, this method combines local boundary information and region statistical-based model synchronously: 1) Boundary term ensures the integrality of lung tissue.2) Region term makes the level set function evolve with global characteristic and independent on initial settings. A penalizing energy term is introduced into the model, which forces the level set function evolving without re-initialization. The method is found to be much more efficient in lung segmentation than other methods that are only based on boundary or region. Results are shown by 3D lung surface reconstruction, which indicates that the method will play an important role in the design of computer-aided diagnostic (CAD) system.

  5. Neighborhood Jams.

    ERIC Educational Resources Information Center

    Zingher, Gary

    1995-01-01

    Examines the role of the neighborhood in books for children and young adults. Discusses community characteristics, historical fiction, "special and scary places," neighborhoods in conflict and harmony, and the neighborhood as a memory base. Presents activities including animated maps, games, murals, small group dramas, and storytelling. (AEF)

  6. Rapid Activation of Motor Responses by Illusory Contours

    ERIC Educational Resources Information Center

    Seydell-Greenwald, Anna; Schmidt, Thomas

    2012-01-01

    Whereas physiological studies indicate that illusory contours (ICs) are signaled in early visual areas at short latencies, behavioral studies are divided as to whether IC processing can proceed in a fast, automatic, bottom-up manner or whether it requires extensive top-down intracortical feedback or even awareness and cognition. Here, we employ a…

  7. Segmentation and tracking in echocardiographic sequences: active contours guided by optical flow estimates

    NASA Technical Reports Server (NTRS)

    Mikic, I.; Krucinski, S.; Thomas, J. D.

    1998-01-01

    This paper presents a method for segmentation and tracking of cardiac structures in ultrasound image sequences. The developed algorithm is based on the active contour framework. This approach requires initial placement of the contour close to the desired position in the image, usually an object outline. Best contour shape and position are then calculated, assuming that at this configuration a global energy function, associated with a contour, attains its minimum. Active contours can be used for tracking by selecting a solution from a previous frame as an initial position in a present frame. Such an approach, however, fails for large displacements of the object of interest. This paper presents a technique that incorporates the information on pixel velocities (optical flow) into the estimate of initial contour to enable tracking of fast-moving objects. The algorithm was tested on several ultrasound image sequences, each covering one complete cardiac cycle. The contour successfully tracked boundaries of mitral valve leaflets, aortic root and endocardial borders of the left ventricle. The algorithm-generated outlines were compared against manual tracings by expert physicians. The automated method resulted in contours that were within the boundaries of intraobserver variability.

  8. Does territoriality modify the relationship between perceived neighborhood challenges and physical activity? A multilevel analysis

    PubMed Central

    Johnson-Lawrence, Vicki; Schulz, Amy J.; Zenk, Shannon N.; Israel, Barbara A.; Rowe, Zachary

    2015-01-01

    Background Individuals who perceive more neighborhood challenges are less physically active. Territoriality, an observable positive marker of social presence and defensible space in the neighborhood, may influence the association between neighborhood challenges and physical activity. We hypothesized that greater territoriality would reduce the negative effects of neighborhood challenges on physical activity levels. Methods Data were collected by the Healthy Environments Partnership in an urban Midwestern city. Multilevel regressions were employed to test associations in a sample of 696 White, Black, and Hispanic adults aged 25+. Results Territoriality moderated associations between residents’ perceptions of neighborhood challenges and physical activity. Contrary to our hypothesis, individuals who perceived more neighborhood challenges and lived in areas with more territoriality markers (e.g. buildings with decorations, buildings with security signage, neighborhood watch signs) were less physically active than other respondents. (b= −2.41, SE=0.84, p<0.01). Conclusions Our findings suggest that associations between perceived neighborhood challenges and physical activity are shaped by the context in which the individual lives. Our study provides empirical evidence that individual perceptions and observed neighborhood characteristics are joint contributors to physical activity, and suggest the need for continued research to characterize the complexity of individual and contextual factors that contribute to physical activity. PMID:25533154

  9. Medical Image Segmentation Based on a Hybrid Region-Based Active Contour Model

    PubMed Central

    Liu, Tingting; Xu, Haiyong; Liu, Zhen; Zhao, Yiming; Tian, Wenzhe

    2014-01-01

    A novel hybrid region-based active contour model is presented to segment medical images with intensity inhomogeneity. The energy functional for the proposed model consists of three weighted terms: global term, local term, and regularization term. The total energy is incorporated into a level set formulation with a level set regularization term, from which a curve evolution equation is derived for energy minimization. Experiments on some synthetic and real images demonstrate that our model is more efficient compared with the localizing region-based active contours (LRBAC) method, proposed by Lankton, and more robust compared with the Chan-Vese (C-V) active contour model. PMID:25028593

  10. Evaluating geodesic active contours in microcalcifications segmentation on mammograms.

    PubMed

    Duarte, Marcelo A; Alvarenga, Andre V; Azevedo, Carolina M; Calas, Maria Julia G; Infantosi, Antonio F C; Pereira, Wagner C A

    2015-12-01

    Breast cancer is the most commonly occurring type of cancer among women, and it is the major cause of female cancer-related deaths worldwide. Its incidence is increasing in developed as well as developing countries. Efficient strategies to reduce the high death rates due to breast cancer include early detection and tumor removal in the initial stages of the disease. Clinical and mammographic examinations are considered the best methods for detecting the early signs of breast cancer; however, these techniques are highly dependent on breast characteristics, equipment quality, and physician experience. Computer-aided diagnosis (CADx) systems have been developed to improve the accuracy of mammographic diagnosis; usually such systems may involve three steps: (i) segmentation; (ii) parameter extraction and selection of the segmented lesions and (iii) lesions classification. Literature considers the first step as the most important of them, as it has a direct impact on the lesions characteristics that will be used in the further steps. In this study, the original contribution is a microcalcification segmentation method based on the geodesic active contours (GAC) technique associated with anisotropic texture filtering as well as the radiologists' knowledge. Radiologists actively participate on the final step of the method, selecting the final segmentation that allows elaborating an adequate diagnosis hypothesis with the segmented microcalcifications presented in a region of interest (ROI). The proposed method was assessed by employing 1000 ROIs extracted from images of the Digital Database for Screening Mammography (DDSM). For the selected ROIs, the rate of adequately segmented microcalcifications to establish a diagnosis hypothesis was at least 86.9%, according to the radiologists. The quantitative test, based on the area overlap measure (AOM), yielded a mean of 0.52±0.20 for the segmented images, when all 2136 segmented microcalcifications were considered. Moreover, a

  11. The associations of perceived neighborhood disorder and physical activity with obesity among African American adolescents

    PubMed Central

    2013-01-01

    Background According to recent research studies, the built and socioeconomic contexts of neighborhoods are associated with African American adolescents’ participation in physical activity and obesity status. However, few research efforts have been devoted to understand how African American adolescents’ perceptions of their neighborhood environments may affect physical activity behaviors and obesity status. The objective of the current study was to use a perceived neighborhood disorder conceptual framework to examine whether physical activity mediated the relationship between perceived neighborhood disorder and obesity status among African American adolescents. Methods The data were obtained from a cross-sectional study that examined social and cultural barriers and facilitators of physical activity among African American adolescents. The study included a sample of 101 African American adolescents age 12 to 16 years and their parents who were recruited from the Birmingham, Alabama metropolitan area. The primary outcome measure was obesity status which was classified using the International Obesity Task Force cut off points. Moderate-to-vigorous physical activity was assessed via accelerometry. Perceived neighborhood disorder was assessed using the Perceived Neighborhood Disorder Scale. Mediation models were used to examine whether the relationship between neighborhood disorder and obesity status was mediated by physical activity. Results Perceived neighborhood disorder was significantly and positively related to obesity status and moderate-to-vigorous physical activity was inversely associated with obesity status. However, there was no evidence to support a significant mediating effect of moderate-to-vigorous physical activity on the relationship between neighborhood disorder and obesity status. Conclusion Future studies should longitudinally assess perceived neighborhood disorder characteristics and childhood adiposity to examine the timing, extent, and the

  12. Moving Beyond Neighborhood: Activity Spaces and Ecological Networks As Contexts for Youth Development

    PubMed Central

    Browning, Christopher R.; Soller, Brian

    2014-01-01

    Many scholars, policy analysts, and practitioners agree that neighborhoods are important contexts for urban youth. Yet, despite decades of research, our knowledge of why and how neighborhoods influence the day-to-day lives of youth is still emerging. Theories about neighborhood effects largely assume that neighborhoods operate to influence youth through exposure-based mechanisms. Extant theoretical approaches, however, have neglected the processes by which neighborhood socioeconomic contexts influence the routine spatial exposures—or activity spaces—of urban residents. In this article, we argue that exposure to organizations, institutions, and other settings that characterize individual activity spaces is a key mechanism through which neighborhoods influence youth outcomes. Moreover, we hypothesize that aggregate patterns of shared local exposure—captured by the concept of ecological networks—are influenced by neighborhood socioeconomic characteristics and are independently consequential for neighborhood youth. Neighborhoods in which residents intersect in space more extensively as a result of routine conventional activities will exhibit higher levels of social capital relevant to youth well-being, including (1) familiarity, (2) beneficial (weak) social ties, (3) trust, (4) shared expectations for pro-social youth behavior (collective efficacy), and (5) the capacity for consistent monitoring of public space. We then consider the implications of ecological networks for understanding the complexities of contextual exposure. We specifically discuss the role of embeddedness in ecological communities—that is, clusters of actors and locations that intersect at higher rates—for understanding contextual influences that are inadequately captured by geographically defined neighborhoods. We conclude with an overview of new approaches to data collection that incorporate insights from an activity-space and ecological-network perspective on neighborhood and

  13. Moving Beyond Neighborhood: Activity Spaces and Ecological Networks As Contexts for Youth Development.

    PubMed

    Browning, Christopher R; Soller, Brian

    2014-01-01

    Many scholars, policy analysts, and practitioners agree that neighborhoods are important contexts for urban youth. Yet, despite decades of research, our knowledge of why and how neighborhoods influence the day-to-day lives of youth is still emerging. Theories about neighborhood effects largely assume that neighborhoods operate to influence youth through exposure-based mechanisms. Extant theoretical approaches, however, have neglected the processes by which neighborhood socioeconomic contexts influence the routine spatial exposures-or activity spaces-of urban residents. In this article, we argue that exposure to organizations, institutions, and other settings that characterize individual activity spaces is a key mechanism through which neighborhoods influence youth outcomes. Moreover, we hypothesize that aggregate patterns of shared local exposure-captured by the concept of ecological networks-are influenced by neighborhood socioeconomic characteristics and are independently consequential for neighborhood youth. Neighborhoods in which residents intersect in space more extensively as a result of routine conventional activities will exhibit higher levels of social capital relevant to youth well-being, including (1) familiarity, (2) beneficial (weak) social ties, (3) trust, (4) shared expectations for pro-social youth behavior (collective efficacy), and (5) the capacity for consistent monitoring of public space. We then consider the implications of ecological networks for understanding the complexities of contextual exposure. We specifically discuss the role of embeddedness in ecological communities-that is, clusters of actors and locations that intersect at higher rates-for understanding contextual influences that are inadequately captured by geographically defined neighborhoods. We conclude with an overview of new approaches to data collection that incorporate insights from an activity-space and ecological-network perspective on neighborhood and contextual influences

  14. Community Activism and the Maintenance of Urban Neighborhoods.

    ERIC Educational Resources Information Center

    Miller, Frederick D.; And Others

    Healthy and successful cities are built out of blocks and neighborhoods. Cities are too large and varied to be regarded or run as uniform entities. Block associations are proposed to be one of the major tools that are available for stabilizing and maintaining urban neighborhoods in a fashion that is both inexpensive and responsive to the needs of…

  15. Conceptualizing and Comparing Neighborhood and Activity Space Measures for Food Environment Research

    PubMed Central

    Crawford, Thomas W.; Pitts, Stephanie B. Jilcott; McGuirt, Jared T.; Keyserling, Thomas C.; Ammerman, Alice S.

    2014-01-01

    Greater accessibility to geospatial technologies has led to a surge of spatialized public health research, much of which has focused on food environments. The purpose of this study was to analyze differing spatial measures of exposure to supermarkets and farmers’ markets among women of reproductive age in eastern North Carolina. Exposure measures were derived using participant-defined neighborhoods, investigator-defined road network neighborhoods, and activity spaces incorporating participants’ time space behaviors. Results showed that mean area for participant-defined neighborhoods (0.04 sq. miles) was much smaller than 2.0 mile road network neighborhoods (3.11 sq. miles) and activity spaces (26.36 sq. miles), and that activity spaces provided the greatest market exposure. The traditional residential neighborhood concept may not be particularly relevant for all places. Time-space approaches capturing activity space may be more relevant, particularly if integrated with mixed methods strategies. PMID:25306420

  16. Inference of Splicing Regulatory Activities by Sequence Neighborhood Analysis

    PubMed Central

    Stadler, Michael B; Shomron, Noam; Yeo, Gene W; Schneider, Aniket; Xiao, Xinshu; Burge, Christopher B

    2006-01-01

    Sequence-specific recognition of nucleic-acid motifs is critical to many cellular processes. We have developed a new and general method called Neighborhood Inference (NI) that predicts sequences with activity in regulating a biochemical process based on the local density of known sites in sequence space. Applied to the problem of RNA splicing regulation, NI was used to predict hundreds of new exonic splicing enhancer (ESE) and silencer (ESS) hexanucleotides from known human ESEs and ESSs. These predictions were supported by cross-validation analysis, by analysis of published splicing regulatory activity data, by sequence-conservation analysis, and by measurement of the splicing regulatory activity of 24 novel predicted ESEs, ESSs, and neutral sequences using an in vivo splicing reporter assay. These results demonstrate the ability of NI to accurately predict splicing regulatory activity and show that the scope of exonic splicing regulatory elements is substantially larger than previously anticipated. Analysis of orthologous exons in four mammals showed that the NI score of ESEs, a measure of function, is much more highly conserved above background than ESE primary sequence. This observation indicates a high degree of selection for ESE activity in mammalian exons, with surprisingly frequent interchangeability between ESE sequences. PMID:17121466

  17. Neighborhood Environment Profiles Related to Physical Activity and Weight Status: A Latent Profile Analysis

    PubMed Central

    Adams, Marc A.; Sallis, James F.; Kerr, Jacqueline; Conway, Terry L.; Saelens, Brian E.; Frank, Lawrence D.; Norman, Gregory J.; Cain, Kelli L.

    2011-01-01

    Background Neighborhood built environments (BE) include combinations of co-existing stimuli influencing physical activity (PA). Dealing with numerous environmental variables and complexity presents a significant challenge. The current analysis explored whether a range of reported BE features associated with adults’ physical activity produced distinct multivariate patterns, and tested whether adults’ PA and body mass differed by BE profiles. Methods Participants (20-65 years, 48.2% female, 26% ethnic minority) were recruited between 2002-2005 from 32 neighborhoods from Seattle-King County, WA (N= 1,287) and Baltimore, MD - Washington, DC regions (N=912). Independent Latent Profile Analyses were conducted in each region with 11 environmental variables from the Neighborhood Environment Walkability Scale. Validity of the neighborhood profiles was examined by their relationship to PA (accelerometer-derived moderate-to-vigorous minutes/day, self-reported minutes/week of walking for transportation and leisure) and self-reported BMI using ANCOVA models. Results Neighborhood profiles for Seattle and Baltimore regions were visually similar, suggesting generalizability. High-walkable recreationally-dense neighborhoods differed significantly from other neighborhood types by as much as 13 MVPA minutes/day, almost 60 minutes/week of walking for transportation, and 75 minutes/week of leisure-time activity. Neighborhood profiles also differed significantly for BMI. Discussion These findings could help identify optimal patterns of environmental attributes that facilitate physical activity and improve weight status. PMID:21382400

  18. A Partition-Based Active Contour Model Incorporating Local Information for Image Segmentation

    PubMed Central

    Wu, Jiaji; Jiao, Licheng; Gong, Maoguo

    2014-01-01

    Active contour models are always designed on the assumption that images are approximated by regions with piecewise-constant intensities. This assumption, however, cannot be satisfied when describing intensity inhomogeneous images which frequently occur in real world images and induced considerable difficulties in image segmentation. A milder assumption that the image is statistically homogeneous within different local regions may better suit real world images. By taking local image information into consideration, an enhanced active contour model is proposed to overcome difficulties caused by intensity inhomogeneity. In addition, according to curve evolution theory, only the region near contour boundaries is supposed to be evolved in each iteration. We try to detect the regions near contour boundaries adaptively for satisfying the requirement of curve evolution theory. In the proposed method, pixels within a selected region near contour boundaries have the opportunity to be updated in each iteration, which enables the contour to be evolved gradually. Experimental results on synthetic and real world images demonstrate the advantages of the proposed model when dealing with intensity inhomogeneity images. PMID:25147868

  19. Perceptions of the Neighborhood Environment and Children’s Afterschool Moderate-to-Vigorous Physical Activity

    PubMed Central

    McDonald, Samantha M; Dowda, Marsha; Colabianchi, Natalie; Porter, Dwayne; Dishman, Rod K.; Pate, Russell R.

    2015-01-01

    Previous research suggests the neighborhood environment may be an important influence on children’s physical activity (PA) behaviors; however, findings are inconsistent. The purpose of this study was to further understand the relationship between perceptions of the neighborhood environment and children’s afterschool moderate-to-vigorous PA (MVPA). Utilizing a structural equation modeling technique, we tested a conceptual model linking parent and child perceptions of the neighborhood environment, parent support for PA, and child outdoor PA with children’s afterschool MVPA. We found that child perception of the neighborhood environment and outdoor PA were positively associated with afterschool MVPA. In addition, parent support for PA positively influenced children’s outdoor PA. The neighborhood environment and outdoor activity appear to play an influential role on children’s afterschool PA behaviors. PMID:25679820

  20. The impact of neighborhood on physical activity in the Jackson Heart Study.

    PubMed

    Robinson, Jennifer C; Wyatt, Sharon B; Dubbert, Patricia M; May, Warren; Sims, Mario

    2016-09-01

    Physical inactivity is an independent risk factor for many diseases. Most research has focused on individual-level factors for physical activity (PA), but evidence suggests that neighborhood is also important. We examined baseline data collected between 2000 and 2004 from 5236 participants in the Jackson Heart Study to determine the effects of neighborhood on 2 types of PA: Active Living (AL), and Sports and Exercise (Sport) in an all-African American cohort. Participants were georeferenced and data from individual baseline questionnaires and US Census were analyzed using descriptive, bivariate, and multilevel models. In both types of PA, neighborhood factors had an independent and additive effect on AL and Sport. Living in an urban (p=0.003) or neighborhood with a higher percentage of residents with less than a high school education (p<0.001) was inversely associated with AL. There was an inverse interaction effect between individual and lower neighborhood education (p=0.01), as well as between age and urban neighborhoods (p=0.02) on AL. Individual level education (OR=1.30) and per capita income (OR=1.07) increased the odds of moderate-to-high sports. Future studies should focus on what contextual aspects of urban or less educated neighborhoods are influential in determining PA, as well as longitudinal multilevel analyses of neighborhood effects on PA. PMID:27473665

  1. Universality in the merging dynamics of parametric active contours: a study in MRI based lung segmentation

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Amit K.; Ray, Nilanjan; Acton, Scott T.

    2005-06-01

    Measurement of lung ventilation is one of the most reliable techniques in diagnosing pulmonary diseases. The time-consuming and bias-prone traditional methods using hyperpolarized H3He and 1H magnetic resonance imageries have recently been improved by an automated technique based on 'multiple active contour evolution'. This method involves a simultaneous evolution of multiple initial conditions, called 'snakes', eventually leading to their 'merging' and is entirely independent of the shapes and sizes of snakes or other parametric details. The objective of this paper is to show, through a theoretical analysis, that the functional dynamics of merging as depicted in the active contour method has a direct analogue in statistical physics and this explains its 'universality'. We show that the multiple active contour method has an universal scaling behaviour akin to that of classical nucleation in two spatial dimensions. We prove our point by comparing the numerically evaluated exponents with an equivalent thermodynamic model.

  2. Multiple Active Contours Guided by Differential Evolution for Medical Image Segmentation

    PubMed Central

    Cruz-Aceves, I.; Avina-Cervantes, J. G.; Lopez-Hernandez, J. M.; Rostro-Gonzalez, H.; Garcia-Capulin, C. H.; Torres-Cisneros, M.; Guzman-Cabrera, R.

    2013-01-01

    This paper presents a new image segmentation method based on multiple active contours guided by differential evolution, called MACDE. The segmentation method uses differential evolution over a polar coordinate system to increase the exploration and exploitation capabilities regarding the classical active contour model. To evaluate the performance of the proposed method, a set of synthetic images with complex objects, Gaussian noise, and deep concavities is introduced. Subsequently, MACDE is applied on datasets of sequential computed tomography and magnetic resonance images which contain the human heart and the human left ventricle, respectively. Finally, to obtain a quantitative and qualitative evaluation of the medical image segmentations compared to regions outlined by experts, a set of distance and similarity metrics has been adopted. According to the experimental results, MACDE outperforms the classical active contour model and the interactive Tseng method in terms of efficiency and robustness for obtaining the optimal control points and attains a high accuracy segmentation. PMID:23983809

  3. Tubular Enhanced Geodesic Active Contours for Continuum Robot Detection using 3D Ultrasound

    PubMed Central

    Ren, Hongliang; Dupont, Pierre E.

    2013-01-01

    Three dimensional ultrasound is a promising imaging modality for minimally invasive robotic surgery. As the robots are typically metallic, they interact strongly with the sound waves in ways that are not modeled by the ultrasound system’s signal processing algorithms. Consequently, they produce substantial imaging artifacts that can make image guidance difficult, even for experienced surgeons. This paper introduces a new approach for detecting curved continuum robots in 3D ultrasound images. The proposed approach combines geodesic active contours with a speed function that is based on enhancing the “tubularity” of the continuum robot. In particular, it takes advantage of the known robot diameter along its length. It also takes advantage of the fact that the robot surface facing the ultrasound probe provides the most accurate image. This method, termed Tubular Enhanced Geodesic Active Contours (TEGAC), is demonstrated through ex vivo intracardiac experiments to offer superior performance compared to conventional active contours. PMID:24231880

  4. Exploiting information geometry to improve the convergence of nonparametric active contours.

    PubMed

    Pereyra, Marcelo; Batatia, Hadj; McLaughlin, Steve

    2015-03-01

    This paper presents a fast converging Riemannian steepest descent method for nonparametric statistical active contour models, with application to image segmentation. Unlike other fast algorithms, the proposed method is general and can be applied to any statistical active contour model from the exponential family, which comprises most of the models considered in the literature. This is achieved by first identifying the intrinsic statistical manifold associated with this class of active contours, and then constructing a steepest descent on that manifold. A key contribution of this paper is to derive a general and tractable closed-form analytic expression for the manifold's Riemannian metric tensor, which allows computing discrete gradient flows efficiently. The proposed methodology is demonstrated empirically and compared with other state of the art approaches on several standard test images, a phantom positron-emission-tomography scan and a B-mode echography of in-vivo human dermis. PMID:25532177

  5. On the Relationship between Variational Level Set-Based and SOM-Based Active Contours

    PubMed Central

    Abdelsamea, Mohammed M.; Gnecco, Giorgio; Gaber, Mohamed Medhat; Elyan, Eyad

    2015-01-01

    Most Active Contour Models (ACMs) deal with the image segmentation problem as a functional optimization problem, as they work on dividing an image into several regions by optimizing a suitable functional. Among ACMs, variational level set methods have been used to build an active contour with the aim of modeling arbitrarily complex shapes. Moreover, they can handle also topological changes of the contours. Self-Organizing Maps (SOMs) have attracted the attention of many computer vision scientists, particularly in modeling an active contour based on the idea of utilizing the prototypes (weights) of a SOM to control the evolution of the contour. SOM-based models have been proposed in general with the aim of exploiting the specific ability of SOMs to learn the edge-map information via their topology preservation property and overcoming some drawbacks of other ACMs, such as trapping into local minima of the image energy functional to be minimized in such models. In this survey, we illustrate the main concepts of variational level set-based ACMs, SOM-based ACMs, and their relationship and review in a comprehensive fashion the development of their state-of-the-art models from a machine learning perspective, with a focus on their strengths and weaknesses. PMID:25960736

  6. On the Relationship between Variational Level Set-Based and SOM-Based Active Contours.

    PubMed

    Abdelsamea, Mohammed M; Gnecco, Giorgio; Gaber, Mohamed Medhat; Elyan, Eyad

    2015-01-01

    Most Active Contour Models (ACMs) deal with the image segmentation problem as a functional optimization problem, as they work on dividing an image into several regions by optimizing a suitable functional. Among ACMs, variational level set methods have been used to build an active contour with the aim of modeling arbitrarily complex shapes. Moreover, they can handle also topological changes of the contours. Self-Organizing Maps (SOMs) have attracted the attention of many computer vision scientists, particularly in modeling an active contour based on the idea of utilizing the prototypes (weights) of a SOM to control the evolution of the contour. SOM-based models have been proposed in general with the aim of exploiting the specific ability of SOMs to learn the edge-map information via their topology preservation property and overcoming some drawbacks of other ACMs, such as trapping into local minima of the image energy functional to be minimized in such models. In this survey, we illustrate the main concepts of variational level set-based ACMs, SOM-based ACMs, and their relationship and review in a comprehensive fashion the development of their state-of-the-art models from a machine learning perspective, with a focus on their strengths and weaknesses. PMID:25960736

  7. Method for non-referential defect characterization using fractal encoding and active contours

    DOEpatents

    Gleason, Shaun S.; Sari-Sarraf, Hamed

    2007-05-15

    A method for identification of anomalous structures, such as defects, includes the steps of providing a digital image and applying fractal encoding to identify a location of at least one anomalous portion of the image. The method does not require a reference image to identify the location of the anomalous portion. The method can further include the step of initializing an active contour based on the location information obtained from the fractal encoding step and deforming an active contour to enhance the boundary delineation of the anomalous portion.

  8. Neighborhood factors associated with physical activity and adequacy of weight gain during pregnancy

    EPA Science Inventory

    Healthy diet, physical activity, smoking, and adequate weight gain are all associated with maternal health and fetal growth during pregnancy. Neighborhood characteristics have been associated with poor maternal and child health outcomes, yet conceptualization of potential mechani...

  9. Housing, the Neighborhood Environment, and Physical Activity among Older African Americans

    PubMed Central

    Hannon, Lonnie; Sawyer, Patricia; Allman, Richard M.

    2013-01-01

    This study examines the association of neighborhood environment, as measured by housing factors, with physical activity among older African Americans. Context is provided on the effects of structural inequality as an inhibitor of health enhancing neighborhood environments. The study population included African Americans participating in the UAB Study of Aging (n=433). Participants demonstrated the ability to walk during a baseline in-home assessment. The strength and independence of housing factors were assessed using neighborhood walking for exercise as the outcome variable. Sociodemographic data, co-morbid medical conditions, and rural/urban residence were included as independent control factors. Homeownership, occupancy, and length of residency maintained positive associations with neighborhood walking independent of control factors. Housing factors appear to be predictive of resident engagement in neighborhood walking. Housing factors, specifically high rates of homeownership, reflect functional and positive neighborhood environments conducive for physical activity. Future interventions seeking to promote health-enhancing behavior should focus on developing housing and built-environment assets within the neighborhood environment. PMID:23745172

  10. Redefining Neighborhoods Using Common Destinations: Social Characteristics of Activity Spaces and Home Census Tracts Compared

    PubMed Central

    Jones, Malia; Pebley, Anne R.

    2014-01-01

    Research on neighborhood effects has focused largely on residential neighborhoods, but people are exposed to many other places in the course of their daily lives—at school, at work, when shopping, and so on. Thus, studies of residential neighborhoods consider only a subset of the social-spatial environment affecting individuals. In this article, we examine the characteristics of adults’ “activity spaces”—spaces defined by locations that individuals visit regularly, in Los Angeles County, California. Using geographic information system (GIS) methods, we define activity spaces in two ways and estimate their socioeconomic characteristics. Our research has two goals. First, we determine whether residential neighborhoods represent the social conditions to which adults are exposed in the course of their regular activities. Second, we evaluate whether particular groups are exposed to a broader or narrower range of social contexts in the course of their daily activities. We find that activity spaces are substantially more heterogeneous in terms of key social characteristics, compared to residential neighborhoods. However, the characteristics of both home neighborhoods and activity spaces are closely associated with individual characteristics. Our results suggest that most people experience substantial segregation across the range of spaces in their daily lives, not just at home. PMID:24719273

  11. Redefining neighborhoods using common destinations: social characteristics of activity spaces and home census tracts compared.

    PubMed

    Jones, Malia; Pebley, Anne R

    2014-06-01

    Research on neighborhood effects has focused largely on residential neighborhoods, but people are exposed to many other places in the course of their daily lives-at school, at work, when shopping, and so on. Thus, studies of residential neighborhoods consider only a subset of the social-spatial environment affecting individuals. In this article, we examine the characteristics of adults' "activity spaces"-spaces defined by locations that individuals visit regularly-in Los Angeles County, California. Using geographic information system (GIS) methods, we define activity spaces in two ways and estimate their socioeconomic characteristics. Our research has two goals. First, we determine whether residential neighborhoods represent the social conditions to which adults are exposed in the course of their regular activities. Second, we evaluate whether particular groups are exposed to a broader or narrower range of social contexts in the course of their daily activities. We find that activity spaces are substantially more heterogeneous in terms of key social characteristics, compared to residential neighborhoods. However, the characteristics of both home neighborhoods and activity spaces are closely associated with individual characteristics. Our results suggest that most people experience substantial segregation across the range of spaces in their daily lives, not just at home. PMID:24719273

  12. Multiple contexts of exposure: Activity spaces, residential neighborhoods, and self-rated health.

    PubMed

    Sharp, Gregory; Denney, Justin T; Kimbro, Rachel T

    2015-12-01

    Although health researchers have made progress in detecting place effects on health, existing work has largely focused on the local residential neighborhood and has lacked a temporal dimension. Little research has integrated both time and space to understand how exposure to multiple contexts - where adults live, work, shop, worship, and seek healthcare - influence and shape health and well-being. This study uses novel longitudinal data from the Los Angeles Family and Neighborhood Survey to delve deeper into the relationship between context and health by considering residential and activity space neighborhoods weighted by the amount of time spent in these contexts. Results from multilevel cross-classified logistic models indicate that contextual exposure to disadvantage, residential or non-residential, is independently associated with a higher likelihood of reporting poor or fair health. We also find support for a contextual incongruence hypothesis. For example, adults living in the most disadvantaged neighborhoods are more likely to report poor or fair health when they spend time in more advantaged neighborhoods than in more disadvantaged ones, while residents of more advantaged neighborhoods report worse health when they spend time in more disadvantaged areas. Our results suggest that certain types of place-based cumulative exposures are associated with a sense of relative neighborhood deprivation that potentially manifests in worse health ratings. PMID:26519605

  13. Comparison of segmentation using fast marching and geodesic active contours methods for bone

    NASA Astrophysics Data System (ADS)

    Bilqis, A.; Widita, R.

    2016-03-01

    Image processing is important in diagnosing diseases or damages of human organs. One of the important stages of image processing is segmentation process. Segmentation is a separation process of the image into regions of certain similar characteristics. It is used to simplify the image to make an analysis easier. The case raised in this study is image segmentation of bones. Bone's image segmentation is a way to get bone dimensions, which is needed in order to make prosthesis that is used to treat broken or cracked bones. Segmentation methods chosen in this study are fast marching and geodesic active contours. This study uses ITK (Insight Segmentation and Registration Toolkit) software. The success of the segmentation was then determined by calculating its accuracy, sensitivity, and specificity. Based on the results, the Active Contours method has slightly higher accuracy and sensitivity values than the fast marching method. As for the value of specificity, fast marching has produced three image results that have higher specificity values compared to those of geodesic active contour's. The result also indicates that both methods have succeeded in performing bone's image segmentation. Overall, geodesic active contours method is quite better than fast marching in segmenting bone images.

  14. Automatic retinal vessel segmentation based on active contours method in Doppler spectral-domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Liu, Wenzhong; Liu, Tan; Song, Wei; Yi, Ji; Zhang, Hao F.

    2013-01-01

    We achieved fast and automatic retinal vessel segmentation by employing the active contours method in Doppler spectral-domain optical coherence tomography (SD-OCT). In a typical OCT B-scan image, we first extracted the phase variations between adjacent A-lines and removed bulk motion. Then we set the initial contour as the boundary of the whole image and iterated until all of the segmented vessel contours became stabilized. Using a typical office computer, the whole segmentation took no more than 50 s, making real-time retinal vessel segmentation possible. We tested the active contours method segmentation in both controlled phantom and in vivo rodent eye images.

  15. Perceived neighborhood environment and physical activity in 11 countries: Do associations differ by country?

    PubMed Central

    2013-01-01

    Background Increasing empirical evidence supports associations between neighborhood environments and physical activity. However, since most studies were conducted in a single country, particularly western countries, the generalizability of associations in an international setting is not well understood. The current study examined whether associations between perceived attributes of neighborhood environments and physical activity differed by country. Methods Population representative samples from 11 countries on five continents were surveyed using comparable methodologies and measurement instruments. Neighborhood environment × country interactions were tested in logistic regression models with meeting physical activity recommendations as the outcome, adjusted for demographic characteristics. Country-specific associations were reported. Results Significant neighborhood environment attribute × country interactions implied some differences across countries in the association of each neighborhood attribute with meeting physical activity recommendations. Across the 11 countries, land-use mix and sidewalks had the most consistent associations with physical activity. Access to public transit, bicycle facilities, and low-cost recreation facilities had some associations with physical activity, but with less consistency across countries. There was little evidence supporting the associations of residential density and crime-related safety with physical activity in most countries. Conclusion There is evidence of generalizability for the associations of land use mix, and presence of sidewalks with physical activity. Associations of other neighborhood characteristics with physical activity tended to differ by country. Future studies should include objective measures of neighborhood environments, compare psychometric properties of reports across countries, and use better specified models to further understand the similarities and differences in associations across countries

  16. Patterns of neighborhood environment attributes related to physical activity across 11 countries: a latent class analysis

    PubMed Central

    2013-01-01

    Background Neighborhood environment studies of physical activity (PA) have been mainly single-country focused. The International Prevalence Study (IPS) presented a rare opportunity to examine neighborhood features across countries. The purpose of this analysis was to: 1) detect international neighborhood typologies based on participants’ response patterns to an environment survey and 2) to estimate associations between neighborhood environment patterns and PA. Methods A Latent Class Analysis (LCA) was conducted on pooled IPS adults (N=11,541) aged 18 to 64 years old (mean=37.5 ±12.8 yrs; 55.6% women) from 11 countries including Belgium, Brazil, Canada, Colombia, Hong Kong, Japan, Lithuania, New Zealand, Norway, Sweden, and the U.S. This subset used the Physical Activity Neighborhood Environment Survey (PANES) that briefly assessed 7 attributes within 10–15 minutes walk of participants’ residences, including residential density, access to shops/services, recreational facilities, public transit facilities, presence of sidewalks and bike paths, and personal safety. LCA derived meaningful subgroups from participants’ response patterns to PANES items, and participants were assigned to neighborhood types. The validated short-form International Physical Activity Questionnaire (IPAQ) measured likelihood of meeting the 150 minutes/week PA guideline. To validate derived classes, meeting the guideline either by walking or total PA was regressed on neighborhood types using a weighted generalized linear regression model, adjusting for gender, age and country. Results A 5-subgroup solution fitted the dataset and was interpretable. Neighborhood types were labeled, “Overall Activity Supportive (52% of sample)”, “High Walkable and Unsafe with Few Recreation Facilities (16%)”, “Safe with Active Transport Facilities (12%)”, “Transit and Shops Dense with Few Amenities (15%)”, and “Safe but Activity Unsupportive (5%)”. Country representation differed by

  17. Disparities in Adolescents' Residence in Neighborhoods Supportive of Physical Activity - United States, 2011-2012.

    PubMed

    Watson, Kathleen B; Harris, Carmen D; Carlson, Susan A; Dorn, Joan M; Fulton, Janet E

    2016-01-01

    In 2013, only 27% of adolescents in grades 9-12 met the current federal guideline for aerobic physical activity (at least 60 minutes of physical activity each day*), and sex and racial/ethnic disparities in meeting the guideline exist (1). The Community Preventive Services Task Force has recommended a range of community-level evidence-based approaches(†) to increase physical activity by improving neighborhood supports for physical activity.(§) To assess the characteristics of adolescents who live in neighborhoods that are supportive of physical activity, CDC analyzed data on U.S. children and adolescents aged 10-17 years (defined as adolescents for this report) from the 2011-2012 National Survey of Children's Health (NSCH). Overall, 65% of U.S. adolescents live in neighborhoods supportive of physical activity, defined as neighborhoods that are perceived as safe and have sidewalks or walking paths and parks, playgrounds, or recreation centers. Adolescents who were Hispanic and non-Hispanic black race/ethnicity; who lived in lower-income households, households with less educated parents, and rural areas; or who were overweight or obese were less likely to live in neighborhoods supportive of physical activity than were white adolescents and adolescents from higher income households, with a more highly educated parent, living in urban areas, and not overweight or obese. Within demographic groups, the largest disparity in the percentage of adolescents living in these neighborhoods was observed between adolescents living in households with a family income <100% of the Federal Poverty Level (FPL) (51%) and adolescents living in households with a family income ≥400% of the FPL (76%). Efforts to improve neighborhood supports, particularly in areas with a substantial percentage of low-income and minority residents, might increase physical activity among adolescents and reduce health disparities. PMID:27309671

  18. Liver segmentation with new supervised method to create initial curve for active contour.

    PubMed

    Zareei, Abouzar; Karimi, Abbas

    2016-08-01

    The liver performs a critical task in the human body; therefore, detecting liver diseases and preparing a robust plan for treating them are both crucial. Liver diseases kill nearly 25,000 Americans every year. A variety of image segmentation methods are available to determine the liver's position and to detect possible liver tumors. Among these is the Active Contour Model (ACM), a framework which has proven very sensitive to initial contour delineation and control parameters. In the proposed method based on image energy, we attempted to obtain an initial segmentation close to the liver's boundary, and then implemented an ACM to improve the initial segmentation. The ACM used in this work incorporates gradient vector flow (GVF) and balloon energy in order to overcome ACM limitations, such as local minima entrapment and initial contour dependency. Additionally, in order to adjust active contour control parameters, we applied a genetic algorithm to produce a proper parameter set close to the optimal solution. The pre-processing method has a better ability to segment the liver tissue during a short time with respect to other mentioned methods in this paper. The proposed method was performed using Sliver CT image datasets. The results show high accuracy, precision, sensitivity, specificity and low overlap error, MSD and runtime with few ACM iterations. PMID:27286186

  19. Where they live, how they play: Neighborhood greenness and outdoor physical activity among preschoolers

    PubMed Central

    2011-01-01

    Background Emerging empirical evidence suggests exposure to "green" environments may encourage higher levels of physical activity among children. Few studies, however, have explored this association exclusively in pre-school aged children in the United States. We examined whether residing in neighborhoods with higher levels of greenness was associated with higher levels of outdoor physical activity among preschoolers. In addition, we also explored whether outdoor playing behaviors (e.g., active vs. quiet) were influenced by levels of neighborhood greenness independent of demographic and parental support factors. Results Higher levels of neighborhood greenness as measured by the Normalized Difference Vegetation Index (NDVI) was associated with higher levels of outdoor playing time among preschool-aged children in our sample. Specifically, a one unit increase in neighborhood greenness increased a child's outdoor playing time by approximately 3 minutes. A dose-response relationship was observed between increasing levels of parental support for physical activity (e.g., time spent playing with children) and child outdoor physical activity (p < 0.01). Conclusions Consistent with previous studies, neighborhood greenness influences physical activity behavior. However, for preschoolers, parental involvement may be more critical for improving physical activity levels. PMID:22165919

  20. Identification of the breast boundary in mammograms using active contour models.

    PubMed

    Ferrari, R J; Rangayyan, R M; Desautels, J E L; Borges, R A; Frère, A F

    2004-03-01

    A method for the identification of the breast boundary in mammograms is presented. The method can be used in the preprocessing stage of a system for computer-aided diagnosis (CAD) of breast cancer and also in the reduction of image file size in picture archiving and communication system applications. The method started with modification of the contrast of the original image. A binarisation procedure was then applied to the image, and the chain-code algorithm was used to find an approximate breast contour. Finally, the identification of the true breast boundary was performed by using the approximate contour as the input to an active contour model algorithm specially tailored for this purpose. After demarcation of the breast boundary, all artifacts outside the breast region were eliminated. The method was applied to 84 medio-lateral oblique mammograms from the Mini-MIAS database. Evaluation of the detected breast boundary was performed based upon the percentage of false-positive and false-negative pixels determined by a quantitative comparison between the contours identified by a radiologist and those identified by the proposed method. The average false positive and false negative rates were 0.41% and 0.58%, respectively. The two radiologists who evaluated the results considered the segmentation results to be acceptable for CAD purposes. PMID:15125150

  1. A 3D interactive multi-object segmentation tool using local robust statistics driven active contours.

    PubMed

    Gao, Yi; Kikinis, Ron; Bouix, Sylvain; Shenton, Martha; Tannenbaum, Allen

    2012-08-01

    Extracting anatomical and functional significant structures renders one of the important tasks for both the theoretical study of the medical image analysis, and the clinical and practical community. In the past, much work has been dedicated only to the algorithmic development. Nevertheless, for clinical end users, a well designed algorithm with an interactive software is necessary for an algorithm to be utilized in their daily work. Furthermore, the software would better be open sourced in order to be used and validated by not only the authors but also the entire community. Therefore, the contribution of the present work is twofolds: first, we propose a new robust statistics based conformal metric and the conformal area driven multiple active contour framework, to simultaneously extract multiple targets from MR and CT medical imagery in 3D. Second, an open source graphically interactive 3D segmentation tool based on the aforementioned contour evolution is implemented and is publicly available for end users on multiple platforms. In using this software for the segmentation task, the process is initiated by the user drawn strokes (seeds) in the target region in the image. Then, the local robust statistics are used to describe the object features, and such features are learned adaptively from the seeds under a non-parametric estimation scheme. Subsequently, several active contours evolve simultaneously with their interactions being motivated by the principles of action and reaction-this not only guarantees mutual exclusiveness among the contours, but also no longer relies upon the assumption that the multiple objects fill the entire image domain, which was tacitly or explicitly assumed in many previous works. In doing so, the contours interact and converge to equilibrium at the desired positions of the desired multiple objects. Furthermore, with the aim of not only validating the algorithm and the software, but also demonstrating how the tool is to be used, we provide

  2. Joint Associations of Residential Density and Neighborhood Involvement with Physical Activity among a Multiethnic Sample of Urban Adults

    ERIC Educational Resources Information Center

    Johnson-Lawrence, Vicki; Schulz, Amy J.; Zenk, Shannon N.; Israel, Barbara A.; Wineman, Jean; Marans, Robert W.; Rowe, Zachary

    2015-01-01

    Regular physical activity is associated with improvements in overall health. Although resident involvement in neighborhood social activities is positively associated with physical activity, neighborhood design features, including residential density, have varied associations with physical activity. Using data from a multiethnic sample of 696…

  3. Neighborhood influences on recreational physical activity and survival after breast cancer

    PubMed Central

    Shariff-Marco, Salma; Sangaramoorthy, Meera; Koo, Jocelyn; Hertz, Andrew; Schupp, Clayton W.; Yang, Juan; John, Esther M.; Gomez, Scarlett L.

    2014-01-01

    Purpose Higher levels of physical activity have been associated with improved survival after breast cancer diagnosis. However, no previous studies have considered the influence of the social and built environment on physical activity and survival among breast cancer patients. Methods Our study included 4,345 women diagnosed with breast cancer (1995–2008) from two population-based studies conducted in the San Francisco Bay Area. We examined questionnaire-based moderate/strenuous recreational physical activity during the 3 years before diagnosis. Neighborhood characteristics were based on data from the 2000 US Census, business listings, parks, farmers’ markets, and Department of Transportation. Survival was evaluated using multivariable Cox proportional hazards models, with follow-up through 2009. Results Women residing in neighborhoods with no fast-food restaurants (vs. fewer fast-food restaurants) to other restaurants, high traffic density, and a high percentage of foreign-born residents were less likely to meet physical activity recommendations set by the American Cancer Society. Women who were not recreationally physically active had a 22 % higher risk of death from any cause than women that were the most active. Poorer overall survival was associated with lower neighborhood socioeconomic status (SES) (p trend = 0.02), whereas better breast cancer-specific survival was associated with a lack of parks, especially among women in high-SES neighborhoods. Conclusion Certain aspects of the neighborhood have independent associations with recreational physical activity among breast cancer patients and their survival. Considering neighborhood factors may aide in the design of more effective, tailored physical activity programs for breast cancer survivors. PMID:25088804

  4. Finding parametric representations of the cortical sulci using an active contour model.

    PubMed

    Vaillant, M; Davatzikos, C

    1997-09-01

    The cortical sulci are brain structures resembling thin convoluted ribbons embedded in three dimensions. The importance of the sulci lies primarily in their relation to the cytoarchitectonic and functional organization of the underlying cortex and in their utilization as features in non-rigid registration methods. This paper presents a methodology for extracting parametric representations of the cerebral sulcus from magnetic resonance images. The proposed methodology is based on deformable models utilizing characteristics of the cortical shape. Specifically, a parametric representation of a sulcus is determined by the motion of an active contour along the medial surface of the corresponding cortical fold. The active contour is initialized along the outer boundary of the brain and deforms toward the deep root of a sulcus under the influence of an external force field, restricting it to lie along the medial surface of the particular cortical fold. A parametric representation of the medial surface of the sulcus is obtained as the active contour traverses the sulcus. Based on the first fundamental form of this representation, the location and degree of an interruption of a sulcus can be readily quantified; based on its second fundamental form, shape properties of the sulcus can be determined. This methodology is tested on magnetic resonance images and it is applied to three medical imaging problems: quantitative morphological analysis of the central sulcus; mapping of functional activation along the primary motor cortex and non-rigid registration of brain images. PMID:9873912

  5. Efficient thermal image segmentation through integration of nonlinear enhancement with unsupervised active contour model

    NASA Astrophysics Data System (ADS)

    Albalooshi, Fatema A.; Krieger, Evan; Sidike, Paheding; Asari, Vijayan K.

    2015-03-01

    Thermal images are exploited in many areas of pattern recognition applications. Infrared thermal image segmentation can be used for object detection by extracting regions of abnormal temperatures. However, the lack of texture and color information, low signal-to-noise ratio, and blurring effect of thermal images make segmenting infrared heat patterns a challenging task. Furthermore, many segmentation methods that are used in visible imagery may not be suitable for segmenting thermal imagery mainly due to their dissimilar intensity distributions. Thus, a new method is proposed to improve the performance of image segmentation in thermal imagery. The proposed scheme efficiently utilizes nonlinear intensity enhancement technique and Unsupervised Active Contour Models (UACM). The nonlinear intensity enhancement improves visual quality by combining dynamic range compression and contrast enhancement, while the UACM incorporates active contour evolutional function and neural networks. The algorithm is tested on segmenting different objects in thermal images and it is observed that the nonlinear enhancement has significantly improved the segmentation performance.

  6. Computer aided weld defect delineation using statistical parametric active contours in radiographic inspection.

    PubMed

    Goumeidane, Aicha Baya; Nacereddine, Nafaa; Khamadja, Mohammed

    2015-01-01

    A perfect knowledge of a defect shape is determinant for the analysis step in automatic radiographic inspection. Image segmentation is carried out on radiographic images and extract defects indications. This paper deals with weld defect delineation in radiographic images. The proposed method is based on a new statistics-based explicit active contour. An association of local and global modeling of the image pixels intensities is used to push the model to the desired boundaries. Furthermore, other strategies are proposed to accelerate its evolution and make the convergence speed depending only on the defect size as selecting a band around the active contour curve. The experimental results are very promising, since experiments on synthetic and radiographic images show the ability of the proposed model to extract a piece-wise homogenous object from very inhomogeneous background, even in a bad quality image. PMID:26410464

  7. Factorial Invariance of the Physical Activity Neighborhood Environment Survey Among Single vs. Multi-family Housing Residents

    PubMed Central

    O’Connor, Daniel P.; Adamus-Leach, Heather J.; Mama, Scherezade K.; Lee, Rebecca E.

    2015-01-01

    Purpose Individual perceptions of one’s neighborhood environment influence decisions about physical activity (PA) participation. Differences between single-family housing neighborhoods vs. multi-family housing neighborhoods may affect perceptions and lead to varying responses on surveys designed to assess perceptions of the neighborhood environment for PA. This study tested the factorial invariance for the Physical Activity Neighborhood Environment Survey (PANES) between residents of single-family vs. multi-family housing neighborhoods. Method This study was a secondary data analysis of PANES ratings from African American and Hispanic or Latina women (n=324) who participated in the Health is Power study (NCI R01CA109403), a multi-site, community based trial to investigate the relationship between neighborhood factors and physical activity adoption and maintenance. Factorial invariance was tested using a series of nested confirmatory factor analysis models. Results The final model was a second-order factor structure with partial invariance of item intercepts. The second-order factor structure and the relationships of the PANES items to the first-order factors (Amenable, Unsafe, and Walkable) and of the first-order factors to the second-order factor (Environment) were invariant between the single-family and multi-family housing neighborhoods groups. Conclusion These findings support the construct validity of PANES, which can be considered valid for measuring neighborhood perceptions among residents of neighborhoods with different housing types. PMID:25751025

  8. Neighborhood environment and physical activity among older adults: do the relationships differ by driving status?

    PubMed

    Ding, Ding; Sallis, James F; Norman, Gregory J; Frank, Lawrence D; Saelens, Brian E; Kerr, Jacqueline; Conway, Terry L; Cain, Kelli; Hovell, Melbourne F; Hofstetter, C Richard; King, Abby C

    2014-07-01

    Some attributes of neighborhood environments are associated with physical activity among older adults. This study examined whether the associations were moderated by driving status. Older adults from neighborhoods differing in walkability and income completed written surveys and wore accelerometers (N = 880, mean age = 75 years, 56% women). Neighborhood environments were measured by geographic information systems and validated questionnaires. Driving status was defined on the basis of a driver's license, car ownership, and feeling comfortable to drive. Outcome variables included accelerometer-based physical activity and self-reported transport and leisure walking. Multilevel generalized linear regression was used. There was no significant Neighborhood Attribute × Driving Status interaction with objective physical activity or reported transport walking. For leisure walking, almost all environmental attributes were positive and significant among driving older adults but not among nondriving older adults (five significant interactions at p < .05). The findings suggest that driving status is likely to moderate the association between neighborhood environments and older adults' leisure walking. PMID:24084049

  9. Soft-tissues Image Processing: Comparison of Traditional Segmentation Methods with 2D active Contour Methods

    NASA Astrophysics Data System (ADS)

    Mikulka, J.; Gescheidtova, E.; Bartusek, K.

    2012-01-01

    The paper deals with modern methods of image processing, especially image segmentation, classification and evaluation of parameters. It focuses primarily on processing medical images of soft tissues obtained by magnetic resonance tomography (MR). It is easy to describe edges of the sought objects using segmented images. The edges found can be useful for further processing of monitored object such as calculating the perimeter, surface and volume evaluation or even three-dimensional shape reconstruction. The proposed solutions can be used for the classification of healthy/unhealthy tissues in MR or other imaging. Application examples of the proposed segmentation methods are shown. Research in the area of image segmentation focuses on methods based on solving partial differential equations. This is a modern method for image processing, often called the active contour method. It is of great advantage in the segmentation of real images degraded by noise with fuzzy edges and transitions between objects. In the paper, results of the segmentation of medical images by the active contour method are compared with results of the segmentation by other existing methods. Experimental applications which demonstrate the very good properties of the active contour method are given.

  10. Neighborhood Environment, Self-Efficacy, and Physical Activity in Urban Adolescents

    ERIC Educational Resources Information Center

    Voorhees, Carolyn C.; Yan, Alice F.; Clifton, Kelly J.; Wang, Min Qi

    2011-01-01

    Objectives: To test the pathways between perceptions of built environment factors and physical activity in urban youth. Methods: Three hundred fifty high school students' perceptions of neighborhood, and barrier self efficacy were measured by a Web survey. Physical activities were assessed using a one-week diary and accelerometers. Results:…

  11. Language Experiences for Your Preschooler. Part 2: Activities in the Neighborhood.

    ERIC Educational Resources Information Center

    Tregaskis, George K.; And Others

    This publication presents a curriculum designed to develop the communication skills of preschool children by introducing parents to a number of learning activities which might evolve from excursions in their neighborhoods and communities. The activities suggested are not closely, complicated, or overly time-consuming. In each section, background…

  12. Intrinsic Bayesian Active Contours for Extraction of Object Boundaries in Images

    PubMed Central

    Srivastava, Anuj

    2010-01-01

    We present a framework for incorporating prior information about high-probability shapes in the process of contour extraction and object recognition in images. Here one studies shapes as elements of an infinite-dimensional, non-linear quotient space, and statistics of shapes are defined and computed intrinsically using differential geometry of this shape space. Prior models on shapes are constructed using probability distributions on tangent bundles of shape spaces. Similar to the past work on active contours, where curves are driven by vector fields based on image gradients and roughness penalties, we incorporate the prior shape knowledge in the form of vector fields on curves. Through experimental results, we demonstrate the use of prior shape models in the estimation of object boundaries, and their success in handling partial obscuration and missing data. Furthermore, we describe the use of this framework in shape-based object recognition or classification. PMID:21076692

  13. Automatic brain cropping enhancement using active contours initialized by a PCNN

    NASA Astrophysics Data System (ADS)

    Swathanthira Kumar, Murali Murugavel; Sullivan, John M., Jr.

    2009-02-01

    Active contours are a popular medical image segmentation strategy. However in practice, its accuracy is dependent on the initialization of the process. The PCNN (Pulse Coupled Neural Network) algorithm developed by Eckhorn to model the observed synchronization of neural assemblies in small mammals such as cats allows for segmenting regions of similar intensity but it lacks a convergence criterion. In this paper we report a novel PCNN based strategy to initialize the zero level contour for automatic brain cropping of T2 weighted MRI image volumes of Long-Evans rats. Individual 2D anatomy slices of the rat brain volume were processed by means of a PCNN and a surrogate image 'signature' was constructed for each slice. By employing a previously trained artificial neural network (ANN) an approximate PCNN iteration (binary mask) was selected. This mask was then used to initialize a region based active contour model to crop the brain region. We tested this hybrid algorithm on 30 rat brain (256*256*12) volumes and compared the results against manually cropped gold standard. The Dice and Jaccard similarity indices were used for numerical evaluation of the proposed hybrid model. The highly successful system yielded an average of 0.97 and 0.94 respectively.

  14. SEGMENTATION OF ELASTOGRAPHIC IMAGES USING A COARSE-TO-FINE ACTIVE CONTOUR MODEL

    PubMed Central

    Liu, Wu; Zagzebski, James A.; Varghese, Tomy; Dyer, Charles R.; Techavipoo, Udomchai; Hall, Timothy J.

    2006-01-01

    Delineation of radiofrequency-ablation-induced coagulation (thermal lesion) boundaries is an important clinical problem that is not well addressed by conventional imaging modalities. Elastography, which produces images of the local strain after small, externally applied compressions, can be used for visualization of thermal coagulations. This paper presents an automated segmentation approach for thermal coagulations on 3-D elastographic data to obtain both area and volume information rapidly. The approach consists of a coarse-to-fine method for active contour initialization and a gradient vector flow, active contour model for deformable contour optimization with the help of prior knowledge of the geometry of general thermal coagulations. The performance of the algorithm has been shown to be comparable to manual delineation of coagulations on elastograms by medical physicists (r = 0.99 for volumes of 36 radiofrequency-induced coagulations). Furthermore, the automatic algorithm applied to elastograms yielded results that agreed with manual delineation of coagulations on pathology images (r = 0.96 for the same 36 lesions). This algorithm has also been successfully applied on in vivo elastograms. PMID:16530098

  15. A Novel Active Contour Model for MRI Brain Segmentation used in Radiotherapy Treatment Planning

    PubMed Central

    Mostaar, Ahmad; Houshyari, Mohammad; Badieyan, Saeedeh

    2016-01-01

    Introduction Brain image segmentation is one of the most important clinical tools used in radiology and radiotherapy. But accurate segmentation is a very difficult task because these images mostly contain noise, inhomogeneities, and sometimes aberrations. The purpose of this study was to introduce a novel, locally statistical active contour model (ACM) for magnetic resonance image segmentation in the presence of intense inhomogeneity with the ability to determine the position of contour and energy diagram. Methods A Gaussian distribution model with different means and variances was used for inhomogeneity, and a moving window was used to map the original image into another domain in which the intensity distributions of inhomogeneous objects were still Gaussian but were better separated. The means of the Gaussian distributions in the transformed domain can be adaptively estimated by multiplying a bias field by the original signal within the window. Then, a statistical energy function is defined for each local region. Also, to evaluate the performance of our method, experiments were conducted on MR images of the brain for segment tumors or normal tissue as visualization and energy functions. Results In the proposed method, we were able to determine the size and position of the initial contour and to count iterations to have a better segmentation. The energy function for 20 to 430 iterations was calculated. The energy function was reduced by about 5 and 7% after 70 and 430 iterations, respectively. These results showed that, with increasing iterations, the energy function decreased, but it decreased faster during the early iterations, after which it decreased slowly. Also, this method enables us to stop the segmentation based on the threshold that we define for the energy equation. Conclusion An active contour model based on the energy function is a useful tool for medical image segmentation. The proposed method combined the information about neighboring pixels that

  16. Neighborhood satisfaction, functional limitations, and self-efficacy influences on physical activity in older women

    PubMed Central

    Morris, Katherine S; McAuley, Edward; Motl, Robert W

    2008-01-01

    Background Perceptions of one's environment and functional status have been linked to physical activity in older adults. However, little is known about these associations over time, and even less about the possible mediators of this relationship. We examined the roles played by neighborhood satisfaction, functional limitations, self-efficacy, and physical activity in a sample of older women over a 6-month period. Methods Participants (N = 137, M age = 69.6 years) completed measures of neighborhood satisfaction, functional limitations, self-efficacy, and physical activity at baseline and again 6 months later. Results Analyses indicated that changes in neighborhood satisfaction and functional limitations had direct effects on residual changes in self-efficacy, and changes in self-efficacy were associated with changes in physical activity at 6 months. Conclusion Our findings support a social cognitive model of physical activity in which neighborhood satisfaction and functional status effects on physical activity are in part mediated by intermediate individual outcomes such as self-efficacy. Additionally, these findings lend support to the position that individual perceptions of both the environment and functional status can have prospective effects on self-efficacy cognitions and ultimately, physical activity behavior. PMID:18304326

  17. The Influence of Parental Nativity, Neighborhood Disadvantage and the Built Environment on Physical Activity Behaviors in Latino Youth

    PubMed Central

    Ohri-Vachaspati, Punam; Yedidia, Michael J.

    2016-01-01

    Little evidence exists examining if parental nativity, neighborhood disadvantage and built environment features are associated with physical activity behaviors in Latino youth. We used a representative sample of Latino youth (n = 616) living in New Jersey to examine parental nativity associations with active transport to school, active use of sidewalks, use of local neighborhood parks, and use of neighborhood physical activity facilities. We estimated prevalence ratios (PR) that accounted for the complex survey design. Latino youth with foreign-born parents were generally more active than their US-born peers, and those with parents in the US 10 years or less were more likely to engage in active transport to school (PR = 1.51, 95 % CI 1.04–2.21), after adjusting for census-based neighborhood disadvantage, self-reported neighborhood measures, and geocoded distance to school. Parental nativity status should be considered in policies or interventions designed to increase physical activity among Latino youth. PMID:24162884

  18. Using Citizen Scientists to Gather, Analyze, and Disseminate Information About Neighborhood Features That Affect Active Living.

    PubMed

    Winter, Sandra J; Goldman Rosas, Lisa; Padilla Romero, Priscilla; Sheats, Jylana L; Buman, Matthew P; Baker, Cathleen; King, Abby C

    2016-10-01

    Many Latinos are insufficiently active, partly due to neighborhoods with little environmental support for physical activity. Multi-level approaches are needed to create health-promoting neighborhoods in disadvantaged communities. Participant "citizen scientists" were adolescent (n = 10, mean age = 12.8 ± 0.6 years) and older adult (n = 10, mean age = 71.3 ± 6.5 years), low income Latinos in North Fair Oaks, California. Citizen scientists conducted environmental assessments to document perceived barriers to active living using the Stanford Healthy Neighborhood Discovery Tool, which records GPS-tracked walking routes, photographs, audio narratives, and survey responses. Using a community-engaged approach, citizen scientists subsequently attended a community meeting to engage in advocacy training, review assessment data, prioritize issues to address and brainstorm potential solutions and partners. Citizen scientists each conducted a neighborhood environmental assessment and recorded 366 photographs and audio narratives. Adolescents (n = 4), older adults (n = 7) and community members (n = 4) collectively identified reducing trash and improving personal safety and sidewalk quality as the priority issues to address. Three adolescent and four older adult citizen scientists volunteered to present study findings to key stakeholders. This study demonstrated that with minimal training, low-income, Latino adolescent and older adult citizen scientists can: (1) use innovative technology to gather information about features of their neighborhood environment that influence active living, (2) analyze their information and identify potential solutions, and (3) engage with stakeholders to advocate for the development of healthier neighborhoods. PMID:26184398

  19. Neighborhood contextual characteristics and leisure-time physical activity: Pró-Saúde Study

    PubMed Central

    Boclin, Karine de Lima Sírio; Faerstein, Eduardo; de Leon, Antônio Carlos Monteiro Ponce

    2014-01-01

    OBJECTIVE To estimate the association between neighborhood contextual variables and leisure-time physical activity. METHODS Data were analyzed for 2,674 adults from Rio de Janeiro, RJ, Southeastern Brazil, participating in the longitudinal study in 1999. Leisure-time physical activity in the two preceding weeks was assessed dichotomously. Sex, age, income, education and marital status were analyzed as individual variables. Neighborhood contextual characteristics were the social development index, the Theil index and the proportion of the area occupied by parks, squares and gardens, categorized in quintiles. The unadjusted and adjusted odds ratios and 95% confidence intervals were estimated using multilevel logistic regression. RESULTS The prevalence of leisure-time physical activity was higher in residents in neighborhoods with higher indices of social development (between 32.3% and 53.1%) and a greater proportion of parks, squares and gardens (between 35.8% and 53.1%). Regarding the social development index, the adjusted odds ratios for physical activity were 1.22 (95%CI 0.93;1.61), 1.44 (95%CI 1.09;1.89), 1.75 (95%CI 1.31;2.34) and 2.25 (95%CI 1.70;3.00) for residents in neighborhoods in the second, third, fourth and fifth quintiles, respectively, compared with residents in neighborhoods in the first quintile. The odds ratios for the proportion of parks, squares and gardens were 0.90 (95%CI 0.69;1.19), 1.41 (95%CI 1.04;1.90), 1.63 (95%CI 1.24;2.14) and 1.05 (95%CI 0.80;1.38) for residents in neighborhoods in the second, third, fourth and fifth quintiles. After adjusting for the other variables, only the social development index continued to be associated with leisure-time physical activity, with odds ratios of 1.41 (95%CI 1.02;1.95); 1.54 (95%CI 1.12;2.12); 1.65 (95%CI 1.14;2.39) and 2.13 (95%CI 1.40;3.25) for residents in neighborhoods in the second, third, fourth and fifth quintiles. CONCLUSIONS Leisure-time physical activity was more common in residents in

  20. Variations in active transport behavior among different neighborhoods and across adult lifestages

    PubMed Central

    Christiansen, Lars Breum; Madsen, Thomas; Schipperijn, Jasper; Ersbøll, Annette K; Troelsen, Jens

    2014-01-01

    Objective Built environment characteristics are closely related to transport behavior, but observed variations could be due to residents own choice of neighborhood called residential self-selection. The aim of this study was to investigate differences in neighborhood walkability and residential self-selection across life stages in relation to active transport behavior. Methods The IPEN walkability index, which consists of four built environment characteristics, was used to define 16 high and low walkable neighborhoods in Aarhus, Denmark (250.000 inhabitants). Transport behavior was assessed using the IPAQ questionnaire. Life stages were categorized in three groups according to age and parental status. A factor analysis was conducted to investigate patterns of self-selection. Multivariable logistic regression analyses were carried out to evaluate the association between walkability and transport behavior i.e. walking, cycling and motorized transport adjusted for residential self-selection and life stages. Results A total of 642 adults aged 20–65 years completed the questionnaire. The highest rated self-selection preference across all groups was a safe and secure neighborhood followed by getting around easily on foot and by bicycle. Three self-selection factors were detected, and varied across the life stages. In the multivariable models high neighborhood walkability was associated with less motorized transport (OR 0.33 95%CI 0.18–0.58), more walking (OR 1.65 95%CI 1.03–2.65) and cycling (OR 1.50 95% CI 1.01–2.23). Self-selection and life stage were also associated with transport behavior, and attenuated the association with walkability. Conclusion This study supports the hypothesis that some variation in transport behavior can be explained by life stages and self-selection, but the association between living in a more walkable neighborhood and active transport is still significant after adjusting for these factors. Life stage significantly moderated the

  1. Segmentation of Bone with Region Based Active Contour Model in PD Weighted MR Images of Shoulder.

    PubMed

    Sezer, Aysun; Sezer, Hasan Basri; Albayrak, Songul

    2015-01-01

    Proton density (PD) weighted MR images present inhomogeneity problem, low signal to noise ratio (SNR) and cannot define bone borders clearly. Segmentation of PD weighted images is hampered with these properties of PD weighted images which even limit the visual inspection. The purpose of this study is to determine the effectiveness of segmentation of humeral head from axial PD MR images with active contour without edge (ACWE) model. We included 219 images from our original data set. We extended the use of speckle reducing anisotropic diffusion (SRAD) in PD MR images by estimation of standard deviation of noise (SDN) from ROI. To overcome the problem of initialization of the initial contour of these region based methods, the location of the initial contour was automatically determined with use of circular Hough transform. For comparison, signed pressure force (SPF), fuzzy C-means, and Gaussian mixture models were applied and segmentation results of all four methods were also compared with the manual segmentation results of an expert. Experimental results on our own database show promising results. This is the first study in the literature to segment normal and pathological humeral heads from PD weighted MR images. PMID:26064185

  2. Examination of Perceived Neighborhood Characteristics and Transportation on Changes in Physical Activity and Sedentary Behavior: The Trial of Activity in Adolescent Girls

    PubMed Central

    Evenson, Kelly R.; Murray, David M.; Birnbaum, Amanda S.; Cohen, Deborah A.

    2010-01-01

    We examined the association between perceived neighborhood characteristics and transport and 2-year changes in accelerometer-determined nonschool MET-weighted moderate to vigorous physical activity (MW-MVPA) and sedentary behavior of adolescent girls. Reporting that children do not play outdoors in their neighborhood, that their neighborhood was well lit, and that there were trails in their neighborhood were each associated with significant decreases in nonschool MW-MVPA. None of the neighborhood or transportation measures was associated with changes in nonschool sedentary behavior. Further work is needed to understand the determinants of the decline in physical activity and the increase in sedentary behavior among adolescent girls. PMID:20615746

  3. Examination of perceived neighborhood characteristics and transportation on changes in physical activity and sedentary behavior: The Trial of Activity in Adolescent Girls.

    PubMed

    Evenson, Kelly R; Murray, David M; Birnbaum, Amanda S; Cohen, Deborah A

    2010-09-01

    We examined the association between perceived neighborhood characteristics and transport and 2-year changes in accelerometer-determined nonschool MET-weighted moderate-to-vigorous physical activity (MW-MVPA) and sedentary behavior of adolescent girls. Reporting that children do not play outdoors in their neighborhood, that their neighborhood was well lit, and that there were trails in their neighborhood were each associated with significant decreases in nonschool MW-MVPA. None of the neighborhood or transportation measures was associated with changes in nonschool sedentary behavior. Further work is needed to understand the determinants of the decline in physical activity and the increase in sedentary behavior among adolescent girls. PMID:20615746

  4. Do Neighborhood Physical Activity Resources and Land Use Influence Physical Activity among African American Public Housing Residents?

    PubMed

    Parker, Nathan H; O'Connor, Daniel P; Kao, Dennis T; Lee, Rebecca E

    2016-01-01

    Few studies have examined neighborhood influences on physical activity (PA) among low-income African Americans living in public housing. This study measured the associations of PA resources and land use with PA among 216 African Americans living in 12 low-income housing developments in Houston, Texas. Neighborhood measures included both detailed information from in-person audits and geographic information systems (GIS) data. Hierarchical linear regression models tested the associations of neighborhood PA resource availability and quality and land use density and diversity with individual-level, self-reported PA. Land use diversity was positively associated with walking among men after controlling for other neighborhood characteristics. Policies that promote land use diversity or improve the pedestrian environment in areas with diverse destinations may encourage PA among public housing residents. PMID:27524771

  5. Neighborhood Factors Influence Physical Activity among African American and Hispanic or Latina Women

    PubMed Central

    Lee, Rebecca E.; Mama, Scherezade K.; Medina, Ashley V.; Ho, Angela; Adamus, Heather J.

    2011-01-01

    This study investigated the relationship between neighborhood street scale elements, such as traffic lights and crossing aids, and physical activity (PA) adoption and maintenance in African American and Hispanic or Latina women. Women (N=309) participated in a 6-month intervention and completed baseline and post-intervention assessments of PA. Trained field assessors completed the Pedestrian Environment Data Scan in participants’ neighborhoods. Adjusted linear regression models found attractiveness for bicycling significantly predicted post-intervention accelerometer-measured PA. Greater traffic control devices and crossing aids were associated with greater PA among women assigned to the PA intervention group, and greater street amenities were associated with greater PA among those in the comparison group. Neighborhood factors may interact favorably with behavioral interventions to promote PA adoption and maintenance, and should be considered in health promotion efforts. PMID:22243907

  6. Segmenting multiple overlapping objects via a hybrid active contour model incorporating shape priors: applications to digital pathology

    NASA Astrophysics Data System (ADS)

    Ali, Sahirzeeshan; Madabhushi, Anant

    2011-03-01

    Active contours and active shape models (ASM) have been widely employed in image segmentation. A major limitation of active contours, however, is in their (a) inability to resolve boundaries of intersecting objects and to (b) handle occlusion. Multiple overlapping objects are typically segmented out as a single object. On the other hand, ASMs are limited by point correspondence issues since object landmarks need to be identified across multiple objects for initial object alignment. ASMs are also are constrained in that they can usually only segment a single object in an image. In this paper, we present a novel synergistic boundary and region-based active contour model that incorporates shape priors in a level set formulation. We demonstrate an application of these synergistic active contour models using multiple level sets to segment nuclear and glandular structures on digitized histopathology images of breast and prostate biopsy specimens. Unlike previous related approaches, our model is able to resolve object overlap and separate occluded boundaries of multiple objects simultaneously. The energy functional of the active contour is comprised of three terms. The first term comprises the prior shape term, modeled on the object of interest, thereby constraining the deformation achievable by the active contour. The second term, a boundary based term detects object boundaries from image gradients. The third term drives the shape prior and the contour towards the object boundary based on region statistics. The results of qualitative and quantitative evaluation on 100 prostate and 14 breast cancer histology images for the task of detecting and segmenting nuclei, lymphocytes, and glands reveals that the model easily outperforms two state of the art segmentation schemes (Geodesic Active Contour (GAC) and Roussons shape based model) and resolves up to 92% of overlapping/occluded lymphocytes and nuclei on prostate and breast cancer histology images.

  7. An Alternative to Residential Neighborhoods: An Exploratory Study of How Activity Spaces and Perception of Neighborhood Social Processes Relate to Maladaptive Parenting

    ERIC Educational Resources Information Center

    Freisthler, Bridget; Thomas, Crystal A.; Curry, Susanna R.; Wolf, Jennifer Price

    2016-01-01

    Background: The environments where parents spend time, such as at work, at their child's school, or with friends and family, may exert a greater influence on their parenting behaviors than the residential neighborhoods where they live. These environments, termed activity spaces, provide individualized information about the where parents go,…

  8. Actin filament tracking based on particle filters and stretching open active contour models.

    PubMed

    Li, Hongsheng; Shen, Tian; Vavylonis, Dimitrios; Huang, Xiaolei

    2009-01-01

    We introduce a novel algorithm for actin filament tracking and elongation measurement. Particle Filters (PF) and Stretching Open Active Contours (SOAC) work cooperatively to simplify the modeling of PF in a one-dimensional state space while naturally integrating filament body constraints to tip estimation. Our algorithm reduces the PF state spaces to one-dimensional spaces by tracking filament bodies using SOAC and probabilistically estimating tip locations along the curve length of SOACs. Experimental evaluation on TIRFM image sequences with very low SNRs demonstrates the accuracy and robustness of this approach. PMID:20426170

  9. Perceiving Object Shape from Specular Highlight Deformation, Boundary Contour Deformation, and Active Haptic Manipulation.

    PubMed

    Norman, J Farley; Phillips, Flip; Cheeseman, Jacob R; Thomason, Kelsey E; Ronning, Cecilia; Behari, Kriti; Kleinman, Kayla; Calloway, Autum B; Lamirande, Davora

    2016-01-01

    It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners) are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped "glaven") for 12 seconds and were required to indicate which of 12 (for bell peppers) or 8 (for glavens) simultaneously visible objects possessed the same shape. The initial single object's shape was defined either by boundary contours alone (i.e., presented as a silhouette), specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition: in this condition, the participants haptically explored with both hands (but could not see) the initial single object for 12 seconds; they then performed the same shape-matching task used in the visual conditions. For both the visual and haptic conditions, motion (rotation in depth or active object manipulation) was present in half of the trials and was not present for the remaining trials. The effect of motion was quantitatively similar for all of the visual and haptic conditions-e.g., the participants' performance in Experiment 1 was 93.5 percent higher in the motion or active haptic manipulation conditions (when compared to the static conditions). The current results demonstrate that deforming specular highlights or boundary contours facilitate 3-D shape perception as much as the motion of objects that possess texture. The current results also indicate that the improvement with motion that occurs for haptics is similar in magnitude to that which occurs for vision. PMID:26863531

  10. Perceiving Object Shape from Specular Highlight Deformation, Boundary Contour Deformation, and Active Haptic Manipulation

    PubMed Central

    Cheeseman, Jacob R.; Thomason, Kelsey E.; Ronning, Cecilia; Behari, Kriti; Kleinman, Kayla; Calloway, Autum B.; Lamirande, Davora

    2016-01-01

    It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners) are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped “glaven”) for 12 seconds and were required to indicate which of 12 (for bell peppers) or 8 (for glavens) simultaneously visible objects possessed the same shape. The initial single object’s shape was defined either by boundary contours alone (i.e., presented as a silhouette), specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition: in this condition, the participants haptically explored with both hands (but could not see) the initial single object for 12 seconds; they then performed the same shape-matching task used in the visual conditions. For both the visual and haptic conditions, motion (rotation in depth or active object manipulation) was present in half of the trials and was not present for the remaining trials. The effect of motion was quantitatively similar for all of the visual and haptic conditions–e.g., the participants’ performance in Experiment 1 was 93.5 percent higher in the motion or active haptic manipulation conditions (when compared to the static conditions). The current results demonstrate that deforming specular highlights or boundary contours facilitate 3-D shape perception as much as the motion of objects that possess texture. The current results also indicate that the improvement with motion that occurs for haptics is similar in magnitude to that which occurs for vision. PMID:26863531

  11. Creative Contours.

    ERIC Educational Resources Information Center

    Fashing, Edward; Appenbrink, David

    1978-01-01

    Students often have difficulty relating contour lines to the shape of a landform. This article describes the construction of a simple landform model designed to help students better understand contour lines. (MA)

  12. Tracking Epithelial Cell Junctions in C. elegans Embryogenesis With Active Contours Guided by SIFT Flow

    PubMed Central

    Lee, Chen-Yu; Gonçalves, Monira; Chisholm, Andrew D.; Cosman, Pamela C.

    2015-01-01

    Quantitative analysis of cell shape in live samples is an important goal in developmental biology. Automated or semiautomated segmentation and tracking of cell nuclei has been successfully implemented in several biological systems. Segmentation and tracking of cell surfaces has been more challenging. Here, we present a new approach to tracking cell junctions in the developing epidermis of C. elegans embryos. Epithelial junctions as visualized with DLG-1::GFP form lines at the subapical circumference of differentiated epidermal cells and delineate changes in epidermal cell shape and position. We develop and compare two approaches for junction segmentation. For the first method (projection approach), 3-D cell boundaries are projected into 2D for segmentation using active contours with a nonintersecting force, and subsequently tracked using scale-invariant feature transform (SIFT) flow. The resulting 2-D tracked boundaries are then back-projected into 3-D space. The second method (volumetric approach) uses a 3-D extended version of active contours guided by SIFT flow in 3-D space. In both methods, cell junctions are manually located at the first time point and tracked in a fully automated way for the remainder of the video. Using these methods, we have generated the first quantitative description of ventral epidermal cell movements and shape changes during epidermal enclosure. PMID:24771564

  13. Locally constrained active contour: a region-based level set for ovarian cancer metastasis segmentation

    NASA Astrophysics Data System (ADS)

    Liu, Jianfei; Yao, Jianhua; Wang, Shijun; Linguraru, Marius George; Summers, Ronald M.

    2014-03-01

    Accurate segmentation of ovarian cancer metastases is clinically useful to evaluate tumor growth and determine follow-up treatment. We present a region-based level set algorithm with localization constraints to segment ovarian cancer metastases. Our approach is established on a representative region-based level set, Chan-Vese model, in which an active contour is driven by region competition. To reduce over-segmentation, we constrain the level set propagation within a narrow image band by embedding a dynamic localization function. The metastasis intensity prior is also estimated from image regions within the level set initialization. The localization function and intensity prior force the level set to stop at the desired metastasis boundaries. Our approach was validated on 19 ovarian cancer metastases with radiologist-labeled ground-truth on contrast-enhanced CT scans from 15 patients. The comparison between our algorithm and geodesic active contour indicated that the volume overlap was 75+/-10% vs. 56+/-6%, the Dice coefficient was 83+/-8% vs. 63+/-8%, and the average surface distance was 2.2+/-0.6mm vs. 4.4+/-0.9mm. Experimental results demonstrated that our algorithm outperformed traditional level set algorithms.

  14. A Method for Lung Boundary Correction Using Split Bregman Method and Geometric Active Contour Model.

    PubMed

    Feng, Changli; Zhang, Jianxun; Liang, Rui

    2015-01-01

    In order to get the extracted lung region from CT images more accurately, a model that contains lung region extraction and edge boundary correction is proposed. Firstly, a new edge detection function is presented with the help of the classic structure tensor theory. Secondly, the initial lung mask is automatically extracted by an improved active contour model which combines the global intensity information, local intensity information, the new edge information, and an adaptive weight. It is worth noting that the objective function of the improved model is converted to a convex model, which makes the proposed model get the global minimum. Then, the central airway was excluded according to the spatial context messages and the position relationship between every segmented region and the rib. Thirdly, a mesh and the fractal theory are used to detect the boundary that surrounds the juxtapleural nodule. Finally, the geometric active contour model is employed to correct the detected boundary and reinclude juxtapleural nodules. We also evaluated the performance of the proposed segmentation and correction model by comparing with their popular counterparts. Efficient computing capability and robustness property prove that our model can correct the lung boundary reliably and reproducibly. PMID:26089976

  15. Aging in Neighborhoods Differing in Walkability and Income: Associations with Physical Activity and Obesity in Older Adults

    PubMed Central

    King, Abby C.; Sallis, James F.; Frank, Lawrence D.; Saelens, Brian E.; Cain, Kelli; Conway, Terry L.; Chapman, James E.; Ahn, David K.; Kerr, Jacqueline

    2011-01-01

    While there is a growing literature on the relations between neighborhood design and health factors such as physical activity and obesity, less focus has been placed on older adults, who may be particularly vulnerable to environmental influences. This study evaluates the relations among objectively measured neighborhood design, mobility impairment, and physical activity and body weight in two U.S. regional samples of community dwelling older adults living in neighborhoods differing in walkability and income levels. An observational design involving two time points six months apart was employed between 2005–2008. U.S. Census block groups in Seattle-King County, Washington and Baltimore. Maryland-Washington DC regions were selected via geographic information systems to maximize variability in walkability and income. Participants were 719 adults ages 66 years and older who were able to complete surveys in English and walk at least 10 feet continuously. Measurements included reported walking or bicycling for errands (i.e., transport activity) and other outdoor aerobic activities measured via the CHAMPS questionnaire: accelerometry-based moderate-to-vigorous physical activity; reported body mass index; and reported lower-extremity mobility impairment measured via the Late-Life Function and Disability Instrument. Across regions, time, and neighborhood income, older adults living in more walkable neighborhoods had more transport activity and moderate-to- vigorous physical activity and lower body mass index relative to those living in less walkable neighborhoods. The most mobility-impaired adults living in more walkable neighborhoods reported transport activity levels that were similar to less mobility-impaired adults living in less walkable neighborhoods. The results add to the small literature aimed at understanding how neighborhood design may influence physical activity and related aspects of health linked with day-to-day function and independence as people age. PMID

  16. "Who Should Have the Neighborhood?" Children's Ideas about the Future Development of an Aging Neighborhood. [And] Moscow, Blueprint for a City: The Only Really Planned City in the World! Instructional Activities Series.

    ERIC Educational Resources Information Center

    Bishop, John E.; And Others

    Two elementary-grade activities on geography are combined. The first activity employs a group discussion approach to investigate neighborhoods and residences. Given data about a neighborhood area in Houston, students make predictions and express feelings about future developments in the area. The second activity investigates urban planning in…

  17. The Association Between Neighborhood Characteristics and Body Size and Physical Activity in the California Teachers Study Cohort

    PubMed Central

    Hurley, Susan; Goldberg, Debbie; Nelson, David O.; Reynolds, Peggy; Bernstein, Leslie; Horn-Ross, Pam L.; Gomez, Scarlett L.

    2012-01-01

    Objectives. We considered interactions between physical activity and body mass index (BMI) and neighborhood factors. Methods. We used recursive partitioning to identify predictors of low recreational physical activity (< 2.5 hours/week) and overweight and obesity (BMI ≥ 25.0 kg/m2) among 118 315 women in the California Teachers Study. Neighborhood characteristics were based on 2000 US Census data and Reference US business listings. Results. Low physical activity and being overweight or obese were associated with individual sociodemographic characteristics, including race/ethnicity and age. Among White women aged 36 to 75 years, living in neighborhoods with more household crowding was associated with a higher probability of low physical activity (54% vs 45% to 51%). In less crowded neighborhoods where more people worked outside the home, the existence of fewer neighborhood amenities was associated with a higher probability of low physical activity (51% vs 46%). Among non–African American middle-aged women, living in neighborhoods with a lower socioeconomic status was associated with a higher probability of being overweight or obese (46% to 59% vs 38% in high–socioeconomic status neighborhoods). Conclusions. Associations between physical activity, overweight and obesity, and the built environment varied by sociodemographic characteristics in this educated population. PMID:21852626

  18. Neighborhood Perceptions and Active School Commuting in Low-Income Cities

    PubMed Central

    DeWeese, Robin S.; Yedidia, Michael J.; Tulloch, David L.; Ohri-Vachaspati, Punam

    2016-01-01

    Background Few children accumulate the recommended ≥60 minutes of physical activity each day. Active travel to and from school (ATS) is a potential source of increased activity for children, accounting for 22% of total trips and time spent traveling by school-aged children. Purpose This study identifies the association of parents’ perceptions of the neighborhood, geospatial variables, and demographic characteristics with ATS among students in four low-income, densely populated urban communities with predominantly minority populations. Methods Data were collected in 2009–2010 from households with school-attending children in four low-income New Jersey cities. Multivariate logistic regression analyses (n=765) identified predictors of ATS. Analyses were conducted in 2012. Results In all, 54% of students actively commuted to school. Students whose parents perceived the neighborhood as very unpleasant for activity were less likely (OR=0.39) to actively commute, as were students living farther from school, with a 6% reduction in ATS for every 0.10 mile increase in distance to school. Perceptions of crime, traffic, and sidewalk conditions were not predictors of ATS. Conclusions Parents’ perceptions of the pleasantness of the neighborhood, independent of the effects of distance from school, may outweigh concerns about crime, traffic, or conditions of sidewalks in predicting active commuting to school in the low-income urban communities studied. Efforts such as cleaning up graffiti, taking care of abandoned buildings, and providing shade trees to improve neighborhood environments are likely to increase ATS, as are efforts that encourage locating schools closer to the populations they serve. PMID:24050414

  19. An Active Contour Model Based on Adaptive Threshold for Extraction of Cerebral Vascular Structures

    PubMed Central

    Wang, Jiaxin; Zhao, Shifeng; Liu, Zifeng; Duan, Fuqing; Pan, Yutong

    2016-01-01

    Cerebral vessel segmentation is essential and helpful for the clinical diagnosis and the related research. However, automatic segmentation of brain vessels remains challenging because of the variable vessel shape and high complex of vessel geometry. This study proposes a new active contour model (ACM) implemented by the level-set method for segmenting vessels from TOF-MRA data. The energy function of the new model, combining both region intensity and boundary information, is composed of two region terms, one boundary term and one penalty term. The global threshold representing the lower gray boundary of the target object by maximum intensity projection (MIP) is defined in the first-region term, and it is used to guide the segmentation of the thick vessels. In the second term, a dynamic intensity threshold is employed to extract the tiny vessels. The boundary term is used to drive the contours to evolve towards the boundaries with high gradients. The penalty term is used to avoid reinitialization of the level-set function. Experimental results on 10 clinical brain data sets demonstrate that our method is not only able to achieve better Dice Similarity Coefficient than the global threshold based method and localized hybrid level-set method but also able to extract whole cerebral vessel trees, including the thin vessels. PMID:27597878

  20. Flux Tensor Constrained Geodesic Active Contours with Sensor Fusion for Persistent Object Tracking.

    PubMed

    Bunyak, Filiz; Palaniappan, Kannappan; Nath, Sumit Kumar; Seetharaman, Gunasekaran

    2007-08-01

    This paper makes new contributions in motion detection, object segmentation and trajectory estimation to create a successful object tracking system. A new efficient motion detection algorithm referred to as the flux tensor is used to detect moving objects in infrared video without requiring background modeling or contour extraction. The flux tensor-based motion detector when applied to infrared video is more accurate than thresholding "hot-spots", and is insensitive to shadows as well as illumination changes in the visible channel. In real world monitoring tasks fusing scene information from multiple sensors and sources is a useful core mechanism to deal with complex scenes, lighting conditions and environmental variables. The object segmentation algorithm uses level set-based geodesic active contour evolution that incorporates the fusion of visible color and infrared edge informations in a novel manner. Touching or overlapping objects are further refined during the segmentation process using an appropriate shape-based model. Multiple object tracking using correspondence graphs is extended to handle groups of objects and occlusion events by Kalman filter-based cluster trajectory analysis and watershed segmentation. The proposed object tracking algorithm was successfully tested on several difficult outdoor multispectral videos from stationary sensors and is not confounded by shadows or illumination variations. PMID:19096530

  1. Flux Tensor Constrained Geodesic Active Contours with Sensor Fusion for Persistent Object Tracking

    PubMed Central

    Bunyak, Filiz; Palaniappan, Kannappan; Nath, Sumit Kumar; Seetharaman, Gunasekaran

    2007-01-01

    This paper makes new contributions in motion detection, object segmentation and trajectory estimation to create a successful object tracking system. A new efficient motion detection algorithm referred to as the flux tensor is used to detect moving objects in infrared video without requiring background modeling or contour extraction. The flux tensor-based motion detector when applied to infrared video is more accurate than thresholding ”hot-spots”, and is insensitive to shadows as well as illumination changes in the visible channel. In real world monitoring tasks fusing scene information from multiple sensors and sources is a useful core mechanism to deal with complex scenes, lighting conditions and environmental variables. The object segmentation algorithm uses level set-based geodesic active contour evolution that incorporates the fusion of visible color and infrared edge informations in a novel manner. Touching or overlapping objects are further refined during the segmentation process using an appropriate shape-based model. Multiple object tracking using correspondence graphs is extended to handle groups of objects and occlusion events by Kalman filter-based cluster trajectory analysis and watershed segmentation. The proposed object tracking algorithm was successfully tested on several difficult outdoor multispectral videos from stationary sensors and is not confounded by shadows or illumination variations. PMID:19096530

  2. Cell spreading analysis with directed edge profile-guided level set active contours.

    PubMed

    Ersoy, I; Bunyak, F; Palaniappan, K; Sun, M; Forgacs, G

    2008-01-01

    Cell adhesion and spreading within the extracellular matrix (ECM) plays an important role in cell motility, cell growth and tissue organization. Measuring cell spreading dynamics enables the investigation of cell mechanosensitivity to external mechanical stimuli, such as substrate rigidity. A common approach to measure cell spreading dynamics is to take time lapse images and quantify cell size and perimeter as a function of time. In our experiments, differences in cell characteristics between different treatments are subtle and require accurate measurements of cell parameters across a large population of cells to ensure an adequate sample size for statistical hypothesis testing. This paper presents a new approach to estimate accurate cell boundaries with complex shapes by applying a modified geodesic active contour level set method that directly utilizes the halo effect typically seen in phase contrast microscopy. Contour evolution is guided by edge profiles in a perpendicular direction to ensure convergence to the correct cell boundary. The proposed approach is tested on bovine aortic endothelial cell images under different treatments, and demonstrates accurate segmentation for a wide range of cell sizes and shapes compared to manual ground truth. PMID:18979769

  3. Shoreline Mapping with Integrated HSI-DEM using Active Contour Method

    NASA Astrophysics Data System (ADS)

    Sukcharoenpong, Anuchit

    Shoreline mapping has been a critical task for federal/state agencies and coastal communities. It supports important applications such as nautical charting, coastal zone management, and legal boundary determination. Current attempts to incorporate data from hyperspectral imagery to increase the efficiency and efficacy of shoreline mapping have been limited due to the complexity in processing its data as well as its inferior spatial resolution when compared to multispectral imagery or to sensors such as LiDAR. As advancements in remote-sensing technologies increase sensor capabilities, the ability to exploit the spectral formation carried in hyperspectral images becomes more imperative. This work employs a new approach to extracting shorelines from AVIRIS hyperspectral images by combination with a LiDAR-based DEM using a multiphase active contour segmentation technique. Several techniques, such as study of object spectra and knowledge-based segmentation for initial contour generation, have been employed in order to achieve a sub-pixel level of accuracy and maintain low computational expenses. Introducing a DEM into hyperspectral image segmentation proves to be a useful tool to eliminate misclassifications and improve shoreline positional accuracy. Experimental results show that mapping shorelines from hyperspectral imagery and a DEM can be a promising approach as many further applications can be developed to exploit the rich information found in hyperspectral imagery.

  4. An Active Contour Model Based on Adaptive Threshold for Extraction of Cerebral Vascular Structures.

    PubMed

    Wang, Jiaxin; Zhao, Shifeng; Liu, Zifeng; Tian, Yun; Duan, Fuqing; Pan, Yutong

    2016-01-01

    Cerebral vessel segmentation is essential and helpful for the clinical diagnosis and the related research. However, automatic segmentation of brain vessels remains challenging because of the variable vessel shape and high complex of vessel geometry. This study proposes a new active contour model (ACM) implemented by the level-set method for segmenting vessels from TOF-MRA data. The energy function of the new model, combining both region intensity and boundary information, is composed of two region terms, one boundary term and one penalty term. The global threshold representing the lower gray boundary of the target object by maximum intensity projection (MIP) is defined in the first-region term, and it is used to guide the segmentation of the thick vessels. In the second term, a dynamic intensity threshold is employed to extract the tiny vessels. The boundary term is used to drive the contours to evolve towards the boundaries with high gradients. The penalty term is used to avoid reinitialization of the level-set function. Experimental results on 10 clinical brain data sets demonstrate that our method is not only able to achieve better Dice Similarity Coefficient than the global threshold based method and localized hybrid level-set method but also able to extract whole cerebral vessel trees, including the thin vessels. PMID:27597878

  5. A circumscribing active contour model for delineation of nuclei and membranes of megakaryocytes in bone marrow trephine biopsy images

    NASA Astrophysics Data System (ADS)

    Song, Tzu-Hsi; Sanchez, Victor; EIDaly, Hesham; Rajpoot, Nasir M.

    2015-03-01

    The assessment of megakaryocytes (MKs) in bone marrow trephine images is an important step in the classification of different subtypes of myeloproliferative neoplasms (MPNs). In general, bone marrow trephine images include several types of cells mixed together, which make it quite difficult to visually identify MKs. In order to aid hematopathologists in the identification and study of MKs, we develop an image processing framework with supervised machine learning approaches and a novel circumscribing active contour model to identify potential MKs and then to accurately delineate the corresponding nucleus and membrane. Specifically, a number of color and texture features are used in a nave Bayesian classifier and an Adaboost classifier to locate the regions with a high probability of depicting MKs. A region-based active contour is used on the candidate MKs to accurately delineate the boundaries of nucleus and membrane. The proposed circumscribing active contour model employs external forces not only based on pixel intensities, but also on the probabilities of depicting MKs as computed by the classifiers. Experimental results suggest that the machine learning approach can detect potential MKs with an accuracy of more than 75%. When our circumscribing active contour model is employed on the candidate MKs, the nucleus and membrane boundaries are segmented with an accuracy of more than 80% as measured by the Dice similarity coefficient. Compared to traditional region-based active contours, the use of additional external forces based on the probability of depicting MKs improves segmentation performance and computational time by an average 5%.

  6. Associations of neighborhood characteristics with active park use: an observational study in two cities in the USA and Belgium

    PubMed Central

    2013-01-01

    Background Public parks can be an important setting for physical activity promotion, but to increase park use and the activity levels of park users, the crucial attributes related to active park use need to be defined. Not only user characteristics and structural park attributes, but also characteristics of the surrounding neighborhood are important to examine. Furthermore, internationally comparable studies are needed, to find out if similar intervention strategies might be effective worldwide. The main aim of this study was to examine whether the overall number of park visitors and their activity levels depend on study site, neighborhood walkability and neighborhood income. Methods Data were collected in 20 parks in Ghent, Belgium and San Diego, USA. Two trained observers systematically coded park characteristics using the Environmental Assessment of Public Recreation Spaces (EAPRS) tool, and park user characteristics using the System for Observing Play and recreation in Communities (SOPARC) tool. Multilevel multiple regression models were conducted in MLwiN 2.25. Results In San Diego parks, activity levels of park visitors and number of vigorously active visitors were higher than in Ghent, while the number of visitors walking and the overall number of park visitors were lower. Neighborhood walkability was positively associated with the overall number of visitors, the number of visitors walking, number of sedentary visitors and mean activity levels of visitors. Neighborhood income was positively associated with the overall number of visitors, but negatively with the number of visitors being vigorously active. Conclusions Neighborhood characteristics are important to explain park use. Neighborhood walkability-related attributes should be taken into account when promoting the use of existing parks or creating new parks. Because no strong differences were found between parks in high- and low-income neighborhoods, it seems that promoting park use might be a promising

  7. Neighborhoods, daily activities, and measuring health risks experienced in urban environments.

    PubMed

    Basta, Luke A; Richmond, Therese S; Wiebe, Douglas J

    2010-12-01

    Studies of place and health often classify a subject's exposure status according to that which is present in their neighborhood of residence. One's neighborhood is often proxied by designating it to be an administratively defined unit such as census tract, to make analysis feasible. Although it is understood that residential space and actual lived space may not correspond and therefore exposure misclassification may result, few studies have the opportunity to investigate the implications of this issue concretely. A population-based case-control study that is currently underway provides one such opportunity. Adolescent victims of assault in Philadelphia, Pennsylvania, USA, and a control sample of adolescents drawn randomly from the community are being enrolled to study how alcohol consumption and time spent nearby alcohol outlets - individual-level and environmental-level risk factors for violence, respectively - over the course of daily activities relate to the likelihood of being assaulted. Data from a rapport-building exercise consist of hand-drawn sketches that subjects drew on street maps when asked to indicate the area considered their neighborhood. The main data consist of self-reported, detailed paths of the routes adolescents traveled from one location to the next over the course of one full day. Having noticed interesting patterns as the data collection phase proceeds, we present here an analysis conducted with the data of 55 control subjects between 15 and 19 years old. We found that hand-drawn neighborhoods and activity paths did not correspond to census tract boundaries, and time subjects spent in close proximity to alcohol outlets during their daily activities was not correlated with the prevalence of alcohol outlets in the census tract of their residence. This served as a useful example demonstrating how classifying subjects as exposed based solely on the prevalence of the exposure in the geographic area of their residence may misrepresent the

  8. The association between green neighborhood environments and active transportation

    EPA Science Inventory

    Background: Urban nature is an important aspect of health-promoting environments. In particular, street trees and green space can provide a low cost approach to improving public health by promoting physical activity, improving mental health, and facilitating social cohesion. Acti...

  9. Actin Filament Tracking Based on Particle Filters and Stretching Open Active Contour Models

    PubMed Central

    Li, Hongsheng; Shen, Tian; Vavylonis, Dimitrios; Huang, Xiaolei

    2010-01-01

    We introduce a novel algorithm for actin filament tracking and elongation measurement. Particle Filters (PF) and Stretching Open Active Contours (SOAC) work cooperatively to simplify the modeling of PF in a one-dimensional state space while naturally integrating filament body constraints to tip estimation. Existing microtubule (MT) tracking methods track either MT tips or entire bodies in high-dimensional state spaces. In contrast, our algorithm reduces the PF state spaces to one-dimensional spaces by tracking filament bodies using SOAC and probabilistically estimating tip locations along the curve length of SOACs. Experimental evaluation on TIRFM image sequences with very low SNRs demonstrates the accuracy and robustness of the proposed approach. PMID:20426170

  10. Brain MRI Tumor Detection using Active Contour Model and Local Image Fitting Energy

    NASA Astrophysics Data System (ADS)

    Nabizadeh, Nooshin; John, Nigel

    2014-03-01

    Automatic abnormality detection in Magnetic Resonance Imaging (MRI) is an important issue in many diagnostic and therapeutic applications. Here an automatic brain tumor detection method is introduced that uses T1-weighted images and K. Zhang et. al.'s active contour model driven by local image fitting (LIF) energy. Local image fitting energy obtains the local image information, which enables the algorithm to segment images with intensity inhomogeneities. Advantage of this method is that the LIF energy functional has less computational complexity than the local binary fitting (LBF) energy functional; moreover, it maintains the sub-pixel accuracy and boundary regularization properties. In Zhang's algorithm, a new level set method based on Gaussian filtering is used to implement the variational formulation, which is not only vigorous to prevent the energy functional from being trapped into local minimum, but also effective in keeping the level set function regular. Experiments show that the proposed method achieves high accuracy brain tumor segmentation results.

  11. A Model for Diagnosing Breast Cancerous Tissue from Thermal Images Using Active Contour and Lyapunov Exponent

    PubMed Central

    GHAYOUMI ZADEH, Hossein; HADDADNIA, Javad; MONTAZERI, Alimohammad

    2016-01-01

    Background: The segmentation of cancerous areas in breast images is important for the early detection of disease. Thermal imaging has advantages, such as being non-invasive, non-radiation, passive, quick, painless, inexpensive, and non-contact. Imaging technique is the focus of this research. Methods: The proposed model in this paper is a combination of surf and corners that are very resistant. Obtained features are resistant to changes in rotation and revolution then with the help of active contours, this feature has been used for segmenting cancerous areas. Results: Comparing the obtained results from the proposed method and mammogram show that proposed method is Accurate and appropriate. Benign and malignance of segmented areas are detected by Lyapunov exponent. Values obtained include TP=91.31%, FN=8.69%, FP=7.26%. Conclusion: The proposed method can classify those abnormally segmented areas of the breast, to the Benign and malignant cancer. PMID:27398339

  12. Interactions between Neighborhood Social Environment and Walkability to Explain Belgian Older Adults' Physical Activity and Sedentary Time.

    PubMed

    Van Holle, Veerle; Van Cauwenberg, Jelle; De Bourdeaudhuij, Ilse; Deforche, Benedicte; Van de Weghe, Nico; Van Dyck, Delfien

    2016-01-01

    This study examined associations between neighborhood social factors and physical activity (PA) and sedentary behavior (SB) in older adults. Furthermore, possible moderating effects of neighborhood walkability were explored. Data from 431 community-dwelling Belgian older adults (≥65 years) were analyzed. Neighborhood social factors included measures of neighboring, social trust and cohesion and social diversity. Neighborhood walkability was measured objectively. Outcome measures were self-reported weekly minutes of domain-specific walking and TV viewing, and accelerometer-assessed weekly minutes of moderate-to-vigorous physical activity (MVPA) and overall SB. A higher frequency of talking to neighbors was associated with higher levels of self-reported walking for transport and for recreation. Moderation analyses showed that only in highly-walkable neighborhoods, higher social diversity of the neighborhood environment was associated with more transport walking; and talking to neighbors and social interactions among neighbors were negatively associated with overall SB and television viewing, respectively. Findings suggest that a combination of a favorable neighborhood social and physical environment are important to promote older adults' PA and limit SB. PMID:27338426

  13. Interactions between Neighborhood Social Environment and Walkability to Explain Belgian Older Adults’ Physical Activity and Sedentary Time

    PubMed Central

    Van Holle, Veerle; Van Cauwenberg, Jelle; De Bourdeaudhuij, Ilse; Deforche, Benedicte; Van de Weghe, Nico; Van Dyck, Delfien

    2016-01-01

    This study examined associations between neighborhood social factors and physical activity (PA) and sedentary behavior (SB) in older adults. Furthermore, possible moderating effects of neighborhood walkability were explored. Data from 431 community-dwelling Belgian older adults (≥65 years) were analyzed. Neighborhood social factors included measures of neighboring, social trust and cohesion and social diversity. Neighborhood walkability was measured objectively. Outcome measures were self-reported weekly minutes of domain-specific walking and TV viewing, and accelerometer-assessed weekly minutes of moderate-to-vigorous physical activity (MVPA) and overall SB. A higher frequency of talking to neighbors was associated with higher levels of self-reported walking for transport and for recreation. Moderation analyses showed that only in highly-walkable neighborhoods, higher social diversity of the neighborhood environment was associated with more transport walking; and talking to neighbors and social interactions among neighbors were negatively associated with overall SB and television viewing, respectively. Findings suggest that a combination of a favorable neighborhood social and physical environment are important to promote older adults’ PA and limit SB. PMID:27338426

  14. Brachial artery vasomotion and transducer pressure effect on measurements by active contour segmentation on ultrasound

    SciTech Connect

    Cary, Theodore W.; Sultan, Laith R.; Sehgal, Chandra M.; Reamer, Courtney B.; Mohler, Emile R.

    2014-02-15

    Purpose: To use feed-forward active contours (snakes) to track and measure brachial artery vasomotion on ultrasound images recorded in both transverse and longitudinal views; and to compare the algorithm's performance in each view. Methods: Longitudinal and transverse view ultrasound image sequences of 45 brachial arteries were segmented by feed-forward active contour (FFAC). The segmented regions were used to measure vasomotion artery diameter, cross-sectional area, and distention both as peak-to-peak diameter and as area. ECG waveforms were also simultaneously extracted frame-by-frame by thresholding a running finite-difference image between consecutive images. The arterial and ECG waveforms were compared as they traced each phase of the cardiac cycle. Results: FFAC successfully segmented arteries in longitudinal and transverse views in all 45 cases. The automated analysis took significantly less time than manual tracing, but produced superior, well-behaved arterial waveforms. Automated arterial measurements also had lower interobserver variability as measured by correlation, difference in mean values, and coefficient of variation. Although FFAC successfully segmented both the longitudinal and transverse images, transverse measurements were less variable. The cross-sectional area computed from the longitudinal images was 27% lower than the area measured from transverse images, possibly due to the compression of the artery along the image depth by transducer pressure. Conclusions: FFAC is a robust and sensitive vasomotion segmentation algorithm in both transverse and longitudinal views. Transverse imaging may offer advantages over longitudinal imaging: transverse measurements are more consistent, possibly because the method is less sensitive to variations in transducer pressure during imaging.

  15. Automated detection of lung tumors in PET/CT images using active contour filter

    NASA Astrophysics Data System (ADS)

    Teramoto, Atsushi; Adachi, Hayato; Tsujimoto, Masakazu; Fujita, Hiroshi; Takahashi, Katsuaki; Yamamuro, Osamu; Tamaki, Tsuneo; Nishio, Masami; Kobayashi, Toshiki

    2015-03-01

    In a previous study, we developed a hybrid tumor detection method that used both computed tomography (CT) and positron emission tomography (PET) images. However, similar to existing computer-aided detection (CAD) schemes, it was difficult to detect low-contrast lesions that touch to the normal organs such as the chest wall or blood vessels in the lung. In the current study, we proposed a novel lung tumor detection method that uses active contour filters to detect the nodules deemed "difficult" in previous CAD schemes. The proposed scheme detects lung tumors using both CT and PET images. As for the detection in CT images, the massive region was first enhanced using an active contour filter (ACF), which is a type of contrast enhancement filter that has a deformable kernel shape. The kernel shape involves closed curves that are connected by several nodes that move iteratively in order to enclose the massive region. The final output of ACF is the difference between the maximum pixel value on the deformable kernel, and pixel value on the center of the filter kernel. Subsequently, the PET images were binarized to detect the regions of increased uptake. The results were integrated, followed by the false positive reduction using 21 characteristic features and three support vector machines. In the experiment, we evaluated the proposed method using 100 PET/CT images. More than half of nodules missed using previous methods were accurately detected. The results indicate that our method may be useful for the detection of lung tumors using PET/CT images.

  16. Spectral embedding based active contour (SEAC): application to breast lesion segmentation on DCE-MRI

    NASA Astrophysics Data System (ADS)

    Agner, Shannon C.; Xu, Jun; Rosen, Mark; Karthigeyan, Sudha; Englander, Sarah; Madabhushi, Anant

    2011-03-01

    Spectral embedding (SE), a graph-based manifold learning method, has previously been shown to be useful in high dimensional data classification. In this work, we present a novel SE based active contour (SEAC) segmentation scheme and demonstrate its applications in lesion segmentation on breast dynamic contrast enhance magnetic resonance imaging (DCE-MRI). In this work, we employ SE on DCE-MRI on a per voxel basis to embed the high dimensional time series intensity vector into a reduced dimensional space, where the reduced embedding space is characterized by the principal eigenvectors. The orthogonal eigenvector-based data representation allows for computation of strong tensor gradients in the spectrally embedded space and also yields improved region statistics that serve as optimal stopping criteria for SEAC. We demonstrate both analytically and empirically that the tensor gradients in the spectrally embedded space are stronger than the corresponding gradients in the original grayscale intensity space. On a total of 50 breast DCE-MRI studies, SEAC yielded a mean absolute difference (MAD) of 3.2+/-2.1 pixels and mean Dice similarity coefficient (DSC) of 0.74+/-0.13 compared to manual ground truth segmentation. An active contour in conjunction with fuzzy c-means (FCM+AC), a commonly used segmentation method for breast DCE-MRI, produced a corresponding MAD of 7.2+/-7.4 pixels and mean DSC of 0.58+/-0.32. In conjunction with a set of 6 quantitative morphological features automatically extracted from the SEAC derived lesion boundary, a support vector machine (SVM) classifier yielded an area under the curve (AUC) of 0.73, for discriminating between 10 benign and 30 malignant lesions; the corresponding SVM classifier with the FCM+AC derived morphological features yielded an AUC of 0.65.

  17. Neighborhood walkability and active travel (walking and cycling) in New York City.

    PubMed

    Freeman, Lance; Neckerman, Kathryn; Schwartz-Soicher, Ofira; Quinn, James; Richards, Catherine; Bader, Michael D M; Lovasi, Gina; Jack, Darby; Weiss, Christopher; Konty, Kevin; Arno, Peter; Viola, Deborah; Kerker, Bonnie; Rundle, Andrew G

    2013-08-01

    Urban planners have suggested that built environment characteristics can support active travel (walking and cycling) and reduce sedentary behavior. This study assessed whether engagement in active travel is associated with neighborhood walkability measured for zip codes in New York City. Data were analyzed on engagement in active travel and the frequency of walking or biking ten blocks or more in the past month, from 8,064 respondents to the New York City 2003 Community Health Survey (CHS). A neighborhood walkability scale that measures: residential, intersection, and subway stop density; land use mix; and the ratio of retail building floor area to retail land area was calculated for each zip code. Data were analyzed using zero-inflated negative binomial regression incorporating survey sample weights and adjusting for respondents' sociodemographic characteristics. Overall, 44 % of respondents reported no episodes of active travel and among those who reported any episode, the mean number was 43.2 episodes per month. Comparing the 75th to the 25th percentile of zip code walkability, the odds ratio for reporting zero episodes of active travel was 0.71 (95 % CI 0.61, 0.83) and the exponentiated beta coefficient for the count of episodes of active travel was 1.13 (95 % CI 1.06, 1.21). Associations between lower walkability and reporting zero episodes of active travel were significantly stronger for non-Hispanic Whites as compared to non-Hispanic Blacks and to Hispanics and for those living in higher income zip codes. The results suggest that neighborhood walkability is associated with higher engagement in active travel. PMID:22941058

  18. Automatic corpus callosum segmentation using a deformable active Fourier contour model

    NASA Astrophysics Data System (ADS)

    Vachet, Clement; Yvernault, Benjamin; Bhatt, Kshamta; Smith, Rachel G.; Gerig, Guido; Cody Hazlett, Heather; Styner, Martin

    2012-03-01

    The corpus callosum (CC) is a structure of interest in many neuroimaging studies of neuro-developmental pathology such as autism. It plays an integral role in relaying sensory, motor and cognitive information from homologous regions in both hemispheres. We have developed a framework that allows automatic segmentation of the corpus callosum and its lobar subdivisions. Our approach employs constrained elastic deformation of flexible Fourier contour model, and is an extension of Szekely's 2D Fourier descriptor based Active Shape Model. The shape and appearance model, derived from a large mixed population of 150+ subjects, is described with complex Fourier descriptors in a principal component shape space. Using MNI space aligned T1w MRI data, the CC segmentation is initialized on the mid-sagittal plane using the tissue segmentation. A multi-step optimization strategy, with two constrained steps and a final unconstrained step, is then applied. If needed, interactive segmentation can be performed via contour repulsion points. Lobar connectivity based parcellation of the corpus callosum can finally be computed via the use of a probabilistic CC subdivision model. Our analysis framework has been integrated in an open-source, end-to-end application called CCSeg both with a command line and Qt-based graphical user interface (available on NITRC). A study has been performed to quantify the reliability of the semi-automatic segmentation on a small pediatric dataset. Using 5 subjects randomly segmented 3 times by two experts, the intra-class correlation coefficient showed a superb reliability (0.99). CCSeg is currently applied to a large longitudinal pediatric study of brain development in autism.

  19. CT liver volumetry using geodesic active contour segmentation with a level-set algorithm

    NASA Astrophysics Data System (ADS)

    Suzuki, Kenji; Epstein, Mark L.; Kohlbrenner, Ryan; Obajuluwa, Ademola; Xu, Jianwu; Hori, Masatoshi; Baron, Richard

    2010-03-01

    Automatic liver segmentation on CT images is challenging because the liver often abuts other organs of a similar density. Our purpose was to develop an accurate automated liver segmentation scheme for measuring liver volumes. We developed an automated volumetry scheme for the liver in CT based on a 5 step schema. First, an anisotropic smoothing filter was applied to portal-venous phase CT images to remove noise while preserving the liver structure, followed by an edge enhancer to enhance the liver boundary. By using the boundary-enhanced image as a speed function, a fastmarching algorithm generated an initial surface that roughly estimated the liver shape. A geodesic-active-contour segmentation algorithm coupled with level-set contour-evolution refined the initial surface so as to more precisely fit the liver boundary. The liver volume was calculated based on the refined liver surface. Hepatic CT scans of eighteen prospective liver donors were obtained under a liver transplant protocol with a multi-detector CT system. Automated liver volumes obtained were compared with those manually traced by a radiologist, used as "gold standard." The mean liver volume obtained with our scheme was 1,520 cc, whereas the mean manual volume was 1,486 cc, with the mean absolute difference of 104 cc (7.0%). CT liver volumetrics based on an automated scheme agreed excellently with "goldstandard" manual volumetrics (intra-class correlation coefficient was 0.95) with no statistically significant difference (p(F<=f)=0.32), and required substantially less completion time. Our automated scheme provides an efficient and accurate way of measuring liver volumes.

  20. Contour complexity and contour detection

    PubMed Central

    Wilder, John; Feldman, Jacob; Singh, Manish

    2015-01-01

    It is well-known that “smooth” chains of oriented elements—contours—are more easily detected amid background noise than more undulating (i.e., “less smooth”) chains. Here, we develop a Bayesian framework for contour detection and show that it predicts that contour detection performance should decrease with the contour's complexity, quantified as the description length (DL; i.e., the negative logarithm of probability integrated along the contour). We tested this prediction in two experiments in which subjects were asked to detect simple open contours amid pixel noise. In Experiment 1, we demonstrate a consistent decline in performance with increasingly complex contours, as predicted by the Bayesian model. In Experiment 2, we confirmed that this effect is due to integrated complexity along the contour, and does not seem to depend on local stretches of linear structure. The results corroborate the probabilistic model of contours, and show how contour detection can be understood as a special case of a more general process—the identification of organized patterns in the environment. PMID:26024453

  1. Changes in the perceived neighborhood environment in relation to changes in physical activity: A longitudinal study from childhood into adolescence.

    PubMed

    D'Haese, Sara; De Meester, Femke; Cardon, Greet; De Bourdeaudhuij, Ilse; Deforche, Benedicte; Van Dyck, Delfien

    2015-05-01

    The aim was to investigate how physical activity and the perceived neighborhood environment in children change when they enter adolescence. Also the relation between changes in the perceived environment and changes in children's physical activity was investigated. In total, 321 children and one of their parents filled out a physical activity questionnaire and the NEWS-Y at two time points (last grade of elementary school and 2 years later). Children also wore an activity monitor. Changes in children's physical activity were dependent on the physical activity domain. Only less than half of children's perceived neighborhood factors changed and about half of the parental perceived neighborhood factors changed. Most of these factors changed towards higher activity friendliness. Changes in the perceived environment were only limitedly related to changes in children's physical activity. PMID:25840351

  2. Sunspots and Coronal Bright Points Tracking using a Hybrid Algorithm of PSO and Active Contour Model

    NASA Astrophysics Data System (ADS)

    Dorotovic, I.; Shahamatnia, E.; Lorenc, M.; Rybansky, M.; Ribeiro, R. A.; Fonseca, J. M.

    2014-02-01

    In the last decades there has been a steady increase of high-resolution data, from ground-based and space-borne solar instruments, and also of solar data volume. These huge image archives require efficient automatic image processing software tools capable of detecting and tracking various features in the solar atmosphere. Results of application of such tools are essential for studies of solar activity evolution, climate change understanding and space weather prediction. The follow up of interplanetary and near-Earth phenomena requires, among others, automatic tracking algorithms that can determine where a feature is located, on successive images taken along the period of observation. Full-disc solar images, obtained both with the ground-based solar telescopes and the instruments onboard the satellites, provide essential observational material for solar physicists and space weather researchers for better understanding the Sun, studying the evolution of various features in the solar atmosphere, and also investigating solar differential rotation by tracking such features along time. Here we demonstrate and discuss the suitability of applying a hybrid Particle Swarm Optimization (PSO) algorithm and Active Contour model for tracking and determining the differential rotation of sunspots and coronal bright points (CBPs) on a set of selected solar images. The results obtained confirm that the proposed approach constitutes a promising tool for investigating the evolution of solar activity and also for automating tracking features on massive solar image archives.

  3. Neighborhood Poverty, Park Use, and Park-Based Physical Activity in a Southern California City

    PubMed Central

    Cohen, Deborah; Han, Bing; Derose, Kathryn; Williamson, Stephanie; Marsh, Terry; Rudick, Jodi; McKenzie, Thomas L.

    2013-01-01

    A rich literature indicates that individuals of lower socio-economic status engage in less leisure time physical activity than individuals of higher socio-economic status. However, the source of the difference is believed to be, in part, due to differential access to resources that support physical activity. However, it has not been shown as to whether equal access to parks can mitigate differences in leisure time physical activity. Using systematic direct observation, we quantified physical activity in neighborhood parks in a large Southern California city located in areas with high, medium, and a low percentage of households in poverty. We documented how neighborhood parks are managed and programmed and also interviewed both a sample of park users and a random sample of households within a mile radius of the parks. We found that parks are used less in high-poverty areas compared to medium- and low-poverty area parks, even after accounting for differences in size, staffing, and programming. The strongest correlates of park use were the number of part time staff, the number of supervised and organized programs, and knowing the park staff. Perceptions of safety were not relevant to park use among those interviewed in the park, however it had a small relationship with reported frequency of park use among local residents. Among park users, time spent watching electronic media was negatively correlated with the frequency of visiting the park. Future research should test whether increasing park staffing and programming will lead to increased park use in high-poverty neighborhoods. PMID:23010338

  4. A validated active contour method driven by parabolic arc model for detection and segmentation of mitochondria.

    PubMed

    Tasel, Serdar F; Mumcuoglu, Erkan U; Hassanpour, Reza Z; Perkins, Guy

    2016-06-01

    Recent studies reveal that mitochondria take substantial responsibility in cellular functions that are closely related to aging diseases caused by degeneration of neurons. These studies emphasize that the membrane and crista morphology of a mitochondrion should receive attention in order to investigate the link between mitochondrial function and its physical structure. Electron microscope tomography (EMT) allows analysis of the inner structures of mitochondria by providing highly detailed visual data from large volumes. Computerized segmentation of mitochondria with minimum manual effort is essential to accelerate the study of mitochondrial structure/function relationships. In this work, we improved and extended our previous attempts to detect and segment mitochondria from transmission electron microcopy (TEM) images. A parabolic arc model was utilized to extract membrane structures. Then, curve energy based active contours were employed to obtain roughly outlined candidate mitochondrial regions. Finally, a validation process was applied to obtain the final segmentation data. 3D extension of the algorithm is also presented in this paper. Our method achieved an average F-score performance of 0.84. Average Dice Similarity Coefficient and boundary error were measured as 0.87 and 14nm respectively. PMID:26956730

  5. EXTRACTION AND ANALYSIS OF ACTIN NETWORKS BASED ON OPEN ACTIVE CONTOUR MODELS

    PubMed Central

    Xu, Ting; Li, Hongsheng; Shen, Tian; Ojkic, Nikola; Vavylonis, Dimitrios; Huang, Xiaolei

    2011-01-01

    Network structures formed by actin filaments are present in many kinds of fluorescence microscopy images. In order to quantify the conformations and dynamics of such actin filaments, we propose a fully automated method to extract actin networks from images and analyze network topology. The method handles well intersecting filaments and, to some extent, overlapping filaments. First we automatically initialize a large number of Stretching Open Active Contours (SOACs) from ridge points detected by searching for plus-to-minus sign changes in the gradient map of the image. These initial SOACs then elongate simultaneously along the bright center-lines of filaments by minimizing an energy function. During their evolution, they may merge or stop growing, thus forming a network that represents the topology of the filament ensemble. We further detect junction points in the network and break the SOACs at junctions to obtain “SOAC segments”. These segments are then re-grouped using a graph-cut spectral clustering method to represent the configuration of actin filaments. The proposed approach is generally applicable to extracting intersecting curvilinear structures in noisy images. We demonstrate its potential using two kinds of data: (1) actin filaments imaged by Total Internal Reflection Fluorescence Microscopy (TIRFM) in vitro; (2) actin cytoskeleton networks in fission yeast imaged by spinning disk confocal microscopy. PMID:21822463

  6. EXTRACTION AND ANALYSIS OF ACTIN NETWORKS BASED ON OPEN ACTIVE CONTOUR MODELS.

    PubMed

    Xu, Ting; Li, Hongsheng; Shen, Tian; Ojkic, Nikola; Vavylonis, Dimitrios; Huang, Xiaolei

    2011-03-30

    Network structures formed by actin filaments are present in many kinds of fluorescence microscopy images. In order to quantify the conformations and dynamics of such actin filaments, we propose a fully automated method to extract actin networks from images and analyze network topology. The method handles well intersecting filaments and, to some extent, overlapping filaments. First we automatically initialize a large number of Stretching Open Active Contours (SOACs) from ridge points detected by searching for plus-to-minus sign changes in the gradient map of the image. These initial SOACs then elongate simultaneously along the bright center-lines of filaments by minimizing an energy function. During their evolution, they may merge or stop growing, thus forming a network that represents the topology of the filament ensemble. We further detect junction points in the network and break the SOACs at junctions to obtain "SOAC segments". These segments are then re-grouped using a graph-cut spectral clustering method to represent the configuration of actin filaments. The proposed approach is generally applicable to extracting intersecting curvilinear structures in noisy images. We demonstrate its potential using two kinds of data: (1) actin filaments imaged by Total Internal Reflection Fluorescence Microscopy (TIRFM) in vitro; (2) actin cytoskeleton networks in fission yeast imaged by spinning disk confocal microscopy. PMID:21822463

  7. Accurate Morphology Preserving Segmentation of Overlapping Cells based on Active Contours

    PubMed Central

    Molnar, Csaba; Jermyn, Ian H.; Kato, Zoltan; Rahkama, Vesa; Östling, Päivi; Mikkonen, Piia; Pietiäinen, Vilja; Horvath, Peter

    2016-01-01

    The identification of fluorescently stained cell nuclei is the basis of cell detection, segmentation, and feature extraction in high content microscopy experiments. The nuclear morphology of single cells is also one of the essential indicators of phenotypic variation. However, the cells used in experiments can lose their contact inhibition, and can therefore pile up on top of each other, making the detection of single cells extremely challenging using current segmentation methods. The model we present here can detect cell nuclei and their morphology even in high-confluency cell cultures with many overlapping cell nuclei. We combine the “gas of near circles” active contour model, which favors circular shapes but allows slight variations around them, with a new data model. This captures a common property of many microscopic imaging techniques: the intensities from superposed nuclei are additive, so that two overlapping nuclei, for example, have a total intensity that is approximately double the intensity of a single nucleus. We demonstrate the power of our method on microscopic images of cells, comparing the results with those obtained from a widely used approach, and with manual image segmentations by experts. PMID:27561654

  8. Accurate Morphology Preserving Segmentation of Overlapping Cells based on Active Contours.

    PubMed

    Molnar, Csaba; Jermyn, Ian H; Kato, Zoltan; Rahkama, Vesa; Östling, Päivi; Mikkonen, Piia; Pietiäinen, Vilja; Horvath, Peter

    2016-01-01

    The identification of fluorescently stained cell nuclei is the basis of cell detection, segmentation, and feature extraction in high content microscopy experiments. The nuclear morphology of single cells is also one of the essential indicators of phenotypic variation. However, the cells used in experiments can lose their contact inhibition, and can therefore pile up on top of each other, making the detection of single cells extremely challenging using current segmentation methods. The model we present here can detect cell nuclei and their morphology even in high-confluency cell cultures with many overlapping cell nuclei. We combine the "gas of near circles" active contour model, which favors circular shapes but allows slight variations around them, with a new data model. This captures a common property of many microscopic imaging techniques: the intensities from superposed nuclei are additive, so that two overlapping nuclei, for example, have a total intensity that is approximately double the intensity of a single nucleus. We demonstrate the power of our method on microscopic images of cells, comparing the results with those obtained from a widely used approach, and with manual image segmentations by experts. PMID:27561654

  9. Racial differences in parental perceptions of the neighborhood as predictors of children's physical activity and sedentary behavior

    PubMed Central

    Budd, Elizabeth L.; Aaron Hipp, J.; Geary, Nora; Dodson, Elizabeth A.

    2015-01-01

    Objective Most U.S. children engage in insufficient physical activity (PA) and spend too much time in sedentary behaviors (SBs), leading to increased risk of obesity and chronic disease. Evidence remains inconsistent on relationships between parental perceptions of the neighborhood and children's PA and SB. This study examines parental neighborhood perceptions, stratified by race, as predictors of children's PA and SB. Methods Relationships were tested with regressions stratified by parental race. The sample included 196 parents, residing in St. Louis, Missouri with a child at home. Participants responded to a mailed survey in 2012. Parental neighborhood perceptions were examined by mean composite scores and individual items. Results For parents of all races, perceived barriers negatively predicted the number of days in a week children engaged in ≥ 60 min of PA. Examining parental neighborhood perceptions by individual item, the perception that drivers exceed neighborhood speed limits was a positive predictor of their children's SB only among white parents. Only among minority-race parents was perceived neighborhood crime rate a positive predictor of their children's SB. Conclusions While predictors of children's PA did not differ widely, several distinct predictors of children's SB by parental race lend support toward further examination of this topic. PMID:26844096

  10. Is Your Neighborhood Designed to Support Physical Activity? A Brief Streetscape Audit Tool

    PubMed Central

    Cain, Kelli L.; Conway, Terry L.; Gavand, Kavita A.; Millstein, Rachel A.; Geremia, Carrie M.; Frank, Lawrence D.; Saelens, Brian E.; Glanz, Karen; King, Abby C.

    2015-01-01

    Introduction Macro level built environment factors (eg, street connectivity, walkability) are correlated with physical activity. Less studied but more modifiable microscale elements of the environment (eg, crosswalks) may also affect physical activity, but short audit measures of microscale elements are needed to promote wider use. This study evaluated the relation of a 15-item neighborhood environment audit tool with a full version of the tool to assess neighborhood design on physical activity in 4 age groups. Methods From the 120-item Microscale Audit of Pedestrian Streetscapes (MAPS) measure of street design, sidewalks, and street crossings, we developed the 15-item version (MAPS-Mini) on the basis of associations with physical activity and attribute modifiability. As a sample of a likely walking route, MAPS-Mini was conducted on a 0.25-mile route from participant residences toward the nearest nonresidential destination for children (n = 758), adolescents (n = 897), younger adults (n = 1,655), and older adults (n = 367). Active transportation and leisure physical activity were measured with age-appropriate surveys, and accelerometers provided objective physical activity measures. Mixed-model regressions were conducted for each MAPS item and a total environment score, adjusted for demographics, participant clustering, and macrolevel walkability. Results Total scores of MAPS-Mini and the 120-item MAPS correlated at r = .85. Total microscale environment scores were significantly related to active transportation in all age groups. Items related to active transport in 3 age groups were presence of sidewalks, curb cuts, street lights, benches, and buffer between street and sidewalk. The total score was related to leisure physical activity and accelerometer measures only in children. Conclusion The MAPS-Mini environment measure is short enough to be practical for use by community groups and planning agencies and is a valid substitute for the full version that is 8

  11. Contribution of Neighborhood Income and Access to Quality Physical Activity Resources to Physical Activity in Ethnic Minority Women Over Time

    PubMed Central

    Lee, Rebecca E.; Mama, Scherezade K.; Adamus-Leach, Heather J.; Soltero, Erica G.

    2015-01-01

    Purpose To create and test an index to indicate both availability and quality of physical activity (PA) resources (PARs), to examine associations between access to quality PARs and changes in PA, and to determine whether this association differed in lower- and higher-income neighborhoods. Design Longitudinal, 6-month intervention. Setting. Houston and Austin, Texas. Subjects African-American and Hispanic or Latina women. Measures Women (N = 410) completed a questionnaire and accelerometry to measure PA. Neighborhoods (N = 163) were classified as lower- or higher-income by median household income at the census-tract level. PARs were audited using the PARA (physical activity resource assessment). Access to quality PARs was determined by a composite index (QPAR) of features, amenities, and incivilities. Analysis Repeated measures analyses of variance were used to examine changes in PA by (1) neighborhood income (lower/higher) and QPAR (lower/higher) groups, and (2) neighborhood income (lower/higher) and number of PARs (lower/higher) groups, adjusting for ethnicity, household income, and body mass index. Results Women in neighborhoods with lower QPAR scores had small increases in self-reported vigorous PA (M Δ = 327.8 metabolic equivalent of task [MET]-min/wk) and decreases in accelerometer PA (M = −3.4 min/d), compared to those with higher QPAR scores who had larger increases in self-reported vigorous PA (M Δ = 709.8 MET-min/wk) and increased accelerometer PA (M = 3.9 min/d). There was a significant interaction between changes in leisure-time PA, QPAR score, and number of PARs (p =.049). Women with both more PARs and higher QPAR scores reported greater increases in leisure-time PA than women with fewer PARs and lower QPAR scores. Conclusion Access to higher-quality PARs can help increase or maintain PA over time regardless of neighborhood income. PAR quality is a separate and distinct, important determinant of PA in ethnic minority women. PMID:24524382

  12. Perceived and Police Reported Neighborhood Crime: Linkages to Adolescent Activity Behaviors and Weight Status

    PubMed Central

    Wall, Melanie; Choo, Tse; Larson, Nicole; Van Riper, David; Neumark-Sztainer, Dianne

    2015-01-01

    Purpose Inadequate physical activity and obesity during adolescence are areas of public health concern. Questions exist about the role of neighborhoods in the etiology of these problems. This research addressed the relationships of perceived and objective reports of neighborhood crime to adolescent physical activity, screen media use, and BMI. Methods Socioeconomically and racially/ethnically diverse adolescents (N=2,455, 53.4% female) from 20 urban, public middle and high schools in Minneapolis/St. Paul, Minnesota responded to a classroom survey in the EAT 2010 (Eating and Activity in Teens) study. Body mass index (BMI) was measured by research staff. Participants’ mean age was 14.6 (SD=2.0); 82.7% represented racial/ethnic groups other than non-Hispanic white. Linear regressions examined associations between crime perceived by adolescents and crime reported to police and the outcomes of interest (BMI z-scores, physical activity, and screen time). Models were stratified by gender and adjusted for age, race/ethnicity, socioeconomic status, and school. Results BMI was positively associated with perceived crime among girls and boys and with reported crime in girls. For girls, there was an association between higher perceived crime and increased screen time; for boys, between higher reported property crime and reduced physical activity. Perceived crime was associated with reported crime, both property and personal, in both genders. Conclusions Few prior studies of adolescents have studied the association between both perceived and reported crime and BMI. Community-based programs for youth should consider addressing adolescents’ safety concerns along with other perceived barriers to physical activity. Interventions targeting actual crime rates are also important. PMID:26206444

  13. Youth Activity Involvement, Neighborhood Adult Support, Individual Decision Making Skills, and Early Adolescent Delinquent Behaviors: Testing a Conceptual Model

    ERIC Educational Resources Information Center

    Crean, Hugh F.

    2012-01-01

    This study examines a cross-sectional structural equation model of participation in youth activities, neighborhood adult support, individual decision making skills, and delinquent behavior in urban middle school youths (n = 2611). Results indicate extracurricular activity participation had both direct and indirect associations with delinquent…

  14. Worksite Neighborhood and Obesogenic Behaviors: Findings Among Employees in the Promoting Activity and Changes in Eating (PACE) Trial

    PubMed Central

    Barrington, Wendy E.; Beresford, Shirley A. A.; Koepsell, Thomas D.; Duncan, Glen E.; Moudon, Anne Vernez

    2015-01-01

    Background Understanding mechanisms linking neighborhood context to health behaviors may provide targets for increasing lifestyle intervention effectiveness. Although associations between home neighborhood and obesogenic behaviors have been studied, less is known about the role of worksite neighborhood. Purpose To evaluate associations between worksite neighborhood context at baseline (2006) and change in obesogenic behaviors of adult employees at follow-up (2007–2009) in a worksite randomized trial to prevent weight gain. Methods Worksite property values were used as an indicator of worksite neighborhood socioeconomic status (NSES). Worksite neighborhood built environment attributes associated with walkability were evaluated as explanatory factors in relationships among worksite NSES, diet, and physical activity behaviors of employees. Behavioral data were collected at baseline (2005–2007) and follow-up (2007–2009). Multilevel linear and logistic models were constructed adjusting for covariates and accounting for clustering within worksites. Product-of-coefficients methods were used to assess mediation. Analyses were performed after study completion (2011–2012). Results Higher worksite NSES was associated with more walking (OR=1.16, 95% CI=1.03, 1.30, p=0.01). Higher density of residential units surrounding worksites was associated with more walking and eating ≥five daily servings of fruits and vegetables, independent of worksite NSES. Residential density partially explained relationships among worksite NSES, fruit and vegetable consumption, and walking. Conclusions Worksite neighborhood context may influence employees’ obesogenic behaviors. Furthermore, residential density around worksites could be an indicator of access to dietary and physical activity–related infrastructure in urban areas. This may be important given the popularity of worksites as venues for obesity prevention efforts. PMID:25442234

  15. Assessment of active play, inactivity and perceived barriers in an inner city neighborhood.

    PubMed

    Kottyan, Gregg; Kottyan, Leah; Edwards, Nicholas M; Unaka, Ndidi I

    2014-06-01

    Avondale, a disadvantaged neighborhood in Cincinnati, lags behind on a number of indicators of child well-being. Childhood obesity has become increasingly prevalent, as one-third of Avondale's kindergarteners are obese or overweight. The study objective was to determine perceptions of the quantity of and obstacles to childhood physical activity in the Avondale community. Caregivers of children from two elementary schools were surveyed to assess their child's physical activity and barriers to being active. Three hundred and forty surveys were returned out of 1,047 for a response rate of 32%. On school days, 41% of caregivers reported that their children spent more than 2 h watching television, playing video games, or spending time on the computer. While over half of respondents reported that their children get more than 2 h of physical activity on school days, 14% of children were reported to be physically active less than 1 h per day. Caregivers identified violence, cost of extracurricular activities, and lack of organized activities as barriers to their child's physical activity. The overwhelming majority of caregivers expressed interest in a program to make local playgrounds safer. In conclusion, children in Avondale are not participating in enough physical activity and are exposed to more screen time than is recommended by the AAP. Safety concerns were identified as a critical barrier to address in future advocacy efforts in this community. This project represents an important step toward increasing the physical activity of children in Avondale and engaging the local community. PMID:24306236

  16. Assessment of carotid diameter and wall thickness in ultrasound images using active contours improved by a multiresolution technique

    NASA Astrophysics Data System (ADS)

    Gutierrez, Marco A.; Pilon, Paulo E.; Lage, Silvia G.; Kopel, Liliane; Carvalho, Ricardo T.; Furuie, Sergio S.

    2002-04-01

    Carotid vessel ultrasound imaging is a reliable non-invasive technique to measure the arterial morphology. Vessel diameter, intima-media thickness (IMT) of the far wall and plaque presence can be reliably determined using B-mode ultrasound. In this paper we describe a semi-automatic approach to measure artery diameter and IMT based on an active contour technique improved by a multiresolution analysis. The operator selects a region-of-interest (ROI) in a series of carotid images obtained from B-mode ultrasound. This set of images is convolved with the corresponding partial derivatives of the Gaussian filter. The filter response is used to compute a 2D gradient magnitude image in order to refine the vessel's boundaries. Using an active contour technique the vessel's border is determined automatically. The near wall media-adventitia (NWMA), far wall media-adventitia (FWMA) and far wall lumen-intima (FWLI) borders are obtained by a least-square fitting of the active contours result. The distance between NWMA and FWLI (vessel diameter) and between FWLI and FWMA (far wall intima-media thickness) are obtained for all images and the mean value is computed during systole and diastole. The proposed method is a reliable and reproducible way of assessing the vessel diameter and far wall intima-media thickness of the carotid artery.

  17. Associations between neighborhood-level factors related to a healthful lifestyle and dietary intake, physical activity, and support for obesity prevention polices among rural adults

    PubMed Central

    Keyserling, Thomas C.; Johnston, Larry; Smith, Tosha W.; McGuirt, Jared T.; Evenson, Kelly R.; Rafferty, Ann P; Gizlice, Ziya; Garcia, Beverly A.; Ammerman, Alice S.

    2014-01-01

    Purpose To examine cross-sectional associations among neighborhood- and individual-level factors related to a healthful lifestyle and dietary intake, physical activity (PA), and support for obesity prevention polices in rural eastern North Carolina adults. Methods We examined perceived neighborhood barriers to a healthful lifestyle, and associations between neighborhood barriers to healthy eating and PA, participants’ support for seven obesity prevention policies, and dependent variables of self-reported dietary and PA behaviors, and measured body mass index (BMI) (n = 366 study participants). We then used participants’ residential addresses and Geographic Information Systems (GIS) software to assess neighborhood-level factors related to access to healthy food and PA opportunities. Correlational analyses and adjusted linear regression models were used to examine associations between neighborhood-level factors related to a healthful lifestyle and dietary and PA behaviors, BMI, and obesity prevention policy support. Results The most commonly reported neighborhood barriers (from a list of 18 potential barriers) perceived by participants included: not enough bicycle lanes and sidewalks, not enough affordable exercise places, too much crime, and no place to buy a quick, healthy meal to go. Higher diet quality was inversely related to perceived and GIS-assessed neighborhood nutrition barriers. There were no significant associations between neighborhood barriers and PA. More perceived neighborhood barriers were positively associated with BMI. Support for obesity prevention policy change was positively associated with perceptions of more neighborhood barriers. Conclusions Neighborhood factors that promote a healthful lifestyle were associated with higher diet quality and lower BMI. Individuals who perceived more neighborhood-level barriers to healthy eating and PA usually supported policies to address those barriers. Future studies should examine mechanisms to garner

  18. A robust active contour edge detection algorithm based on local Gaussian statistical model for oil slick remote sensing image

    NASA Astrophysics Data System (ADS)

    Jing, Yu; Wang, Yaxuan; Liu, Jianxin; Liu, Zhaoxia

    2015-08-01

    Edge detection is a crucial method for the location and quantity estimation of oil slick when oil spills on the sea. In this paper, we present a robust active contour edge detection algorithm for oil spill remote sensing images. In the proposed algorithm, we define a local Gaussian data fitting energy term with spatially varying means and variances, and this data fitting energy term is introduced into a global minimization active contour (GMAC) framework. The energy function minimization is achieved fast by a dual formulation of the weighted total variation norm. The proposed algorithm avoids the existence of local minima, does not require the definition of initial contour, and is robust to weak boundaries, high noise and severe intensity inhomogeneity exiting in oil slick remote sensing images. Furthermore, the edge detection of oil slick and the correction of intensity inhomogeneity are simultaneously achieved via the proposed algorithm. The experiment results have shown that a superior performance of proposed algorithm over state-of-the-art edge detection algorithms. In addition, the proposed algorithm can also deal with the special images with the object and background of the same intensity means but different variances.

  19. Feed-forward active contour analysis for improved brachial artery reactivity testing.

    PubMed

    Pugliese, Daniel N; Sehgal, Chandra M; Sultan, Laith R; Reamer, Courtney B; Mohler, Emile R

    2016-08-01

    The object of this study was to utilize a novel feed-forward active contour (FFAC) algorithm to find a reproducible technique for analysis of brachial artery reactivity. Flow-mediated dilation (FMD) is an important marker of vascular endothelial function but has not been adopted for widespread clinical use given its technical limitations, including inter-observer variability and differences in technique across clinical sites. We developed a novel FFAC algorithm with the goal of validating a more reliable standard. Forty-six healthy volunteers underwent FMD measurement according to the standard technique. Ultrasound videos lasting 5-10 seconds each were obtained pre-cuff inflation and at minutes 1 through 5 post-cuff deflation in longitudinal and transverse views. Automated segmentation using the FFAC algorithm with initial boundary definition from three different observers was used to analyze the images to measure diameter/cross-sectional area over the cardiac cycle. The %FMD was calculated for average, minimum, and maximum diameters/areas. Using the FFAC algorithm, the population-specific coefficient of variation (CV) at end-diastole was 3.24% for transverse compared to 9.96% for longitudinal measurements; the subject-specific CV was 15.03% compared to 57.41%, respectively. For longitudinal measurements made via the conventional method, the population-specific CV was 4.77% and subject-specific CV was 117.79%. The intraclass correlation coefficient (ICC) for transverse measurements was 0.97 (95% CI: 0.95-0.98) compared to 0.90 (95% CI: 0.84-0.94) for longitudinal measurements with FFAC and 0.72 (95% CI: 0.51-0.84) for conventional measurements. In conclusion, transverse views using the novel FFAC method provide less inter-observer variability than traditional longitudinal views. Improved reproducibility may allow adoption of FMD testing in a clinical setting. The FFAC algorithm is a robust technique that should be evaluated further for its ability to replace the

  20. Longitudinal effects of parental child and neighborhood factors on moderate vigorous physical activity and sedentary time in Latino children

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Moderate-vigorous physical activity (%MVPA) confers beneficial effects on child musculoskeletal health, cardiovascular fitness, and psychosocial well-being; in contrast, sedentary time (%SED) is emerging as a risk factor for health. This study aimed to identify parental, child and neighborhood facto...

  1. Contour Mapping

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In the early 1990s, the Ohio State University Center for Mapping, a NASA Center for the Commercial Development of Space (CCDS), developed a system for mobile mapping called the GPSVan. While driving, the users can map an area from the sophisticated mapping van equipped with satellite signal receivers, video cameras and computer systems for collecting and storing mapping data. George J. Igel and Company and the Ohio State University Center for Mapping advanced the technology for use in determining the contours of a construction site. The new system reduces the time required for mapping and staking, and can monitor the amount of soil moved.

  2. Segmenting the thoracic, abdominal and pelvic musculature on CT scans combining atlas-based model and active contour model

    NASA Astrophysics Data System (ADS)

    Zhang, Weidong; Liu, Jiamin; Yao, Jianhua; Summers, Ronald M.

    2013-03-01

    Segmentation of the musculature is very important for accurate organ segmentation, analysis of body composition, and localization of tumors in the muscle. In research fields of computer assisted surgery and computer-aided diagnosis (CAD), muscle segmentation in CT images is a necessary pre-processing step. This task is particularly challenging due to the large variability in muscle structure and the overlap in intensity between muscle and internal organs. This problem has not been solved completely, especially for all of thoracic, abdominal and pelvic regions. We propose an automated system to segment the musculature on CT scans. The method combines an atlas-based model, an active contour model and prior segmentation of fat and bones. First, body contour, fat and bones are segmented using existing methods. Second, atlas-based models are pre-defined using anatomic knowledge at multiple key positions in the body to handle the large variability in muscle shape. Third, the atlas model is refined using active contour models (ACM) that are constrained using the pre-segmented bone and fat. Before refining using ACM, the initialized atlas model of next slice is updated using previous atlas. The muscle is segmented using threshold and smoothed in 3D volume space. Thoracic, abdominal and pelvic CT scans were used to evaluate our method, and five key position slices for each case were selected and manually labeled as the reference. Compared with the reference ground truth, the overlap ratio of true positives is 91.1%+/-3.5%, and that of false positives is 5.5%+/-4.2%.

  3. Three-Dimensional Contour Maps

    ERIC Educational Resources Information Center

    Lee, Edward

    2005-01-01

    In summary, this highly conceptual activity helps middle school students understand that the lines on the contour map represent intersections of the surface of the landform with regularly spaced horizontal planes. Building the landform and relating its features to the contour map offer many opportunities for visualization, all grounded in concrete…

  4. Segmentation of Uterus Using Laparoscopic Ultrasound by an Image-Based Active Contour Approach for Guiding Gynecological Diagnosis and Surgery.

    PubMed

    Gong, Xue-Hao; Lu, Jun; Liu, Jin; Deng, Ying-Yuan; Liu, Wei-Zong; Huang, Xian; Yang, Yong-Heng; Xu, Qin; Yu, Zhi-Ying

    2015-01-01

    In laparoscopic gynecologic surgery, ultrasound has been typically implemented to diagnose urological and gynecological conditions. We applied laparoscopic ultrasonography (using Esaote 7.5~10MHz laparoscopic transducer) on the retrospective analyses of 42 women subjects during laparoscopic extirpation and excision of gynecological tumors in our hospital from August 2011 to August 2013. The objective of our research is to develop robust segmentation technique for isolation and identification of the uterus from the ultrasound images, so as to assess, locate and guide in removing the lesions during laparoscopic operations. Our method enables segmentation of the uterus by the active contour algorithm. We evaluated 42 in-vivo laparoscopic images acquired from the 42 patients (age 39.1 ± 7.2 years old) and selected images pertaining to 4 cases of congenital uterine malformations and 2 cases of pelvic adhesions masses. These cases (n = 6) were used for our uterus segmentation experiments. Based on them, the active contour method was compared with the manual segmentation method by a medical expert using linear regression and the Bland-Altman analysis (used to measure the correlation and the agreement). Then, the Dice and Jaccard indices are computed for measuring the similarity of uterus segmented between computational and manual methods. Good correlation was achieved whereby 84%-92% results fall within the 95% confidence interval in the Student t-test) and we demonstrate that the proposed segmentation method of uterus using laparoscopic images is effective. PMID:26516767

  5. Segmentation of Uterus Using Laparoscopic Ultrasound by an Image-Based Active Contour Approach for Guiding Gynecological Diagnosis and Surgery

    PubMed Central

    Gong, Xue-Hao; Lu, Jun; Liu, Jin; Deng, Ying-Yuan; Liu, Wei-Zong; Huang, Xian; Yang, Yong-Heng; Xu, Qin; Yu, Zhi-Ying

    2015-01-01

    In laparoscopic gynecologic surgery, ultrasound has been typically implemented to diagnose urological and gynecological conditions. We applied laparoscopic ultrasonography (using Esaote 7.5~10MHz laparoscopic transducer) on the retrospective analyses of 42 women subjects during laparoscopic extirpation and excision of gynecological tumors in our hospital from August 2011 to August 2013. The objective of our research is to develop robust segmentation technique for isolation and identification of the uterus from the ultrasound images, so as to assess, locate and guide in removing the lesions during laparoscopic operations. Our method enables segmentation of the uterus by the active contour algorithm. We evaluated 42 in-vivo laparoscopic images acquired from the 42 patients (age 39.1 ± 7.2 years old) and selected images pertaining to 4 cases of congenital uterine malformations and 2 cases of pelvic adhesions masses. These cases (n = 6) were used for our uterus segmentation experiments. Based on them, the active contour method was compared with the manual segmentation method by a medical expert using linear regression and the Bland-Altman analysis (used to measure the correlation and the agreement). Then, the Dice and Jaccard indices are computed for measuring the similarity of uterus segmented between computational and manual methods. Good correlation was achieved whereby 84%–92% results fall within the 95% confidence interval in the Student t-test) and we demonstrate that the proposed segmentation method of uterus using laparoscopic images is effective. PMID:26516767

  6. Quasi-causal associations of physical activity and neighborhood walkability with body mass index: A twin study

    PubMed Central

    Duncan, Glen E.; Cash, Stephanie Whisnant; Horn, Erin E.; Turkheimer, Eric

    2014-01-01

    Objective Physical activity, neighborhood walkability, and body mass index (BMI, kg/m2) associations were tested using quasi-experimental twin methods. We hypothesized that physical activity and walkability were independently associated with BMI within twin pairs, controlling for genetic and environmental background shared between them. Methods Data were from 6,376 (64% female; 58% identical) same-sex pairs, University of Washington Twin Registry, 2008–2013. Neighborhood walking, moderate-to-vigorous physical activity (MVPA), and BMI were self-reported. Residential address was used to calculate walkability. Phenotypic (non-genetically informed) and biometric (genetically informed) regression was employed, controlling for age, sex, and race. Results Walking and MVPA were associated with BMI in phenotypic analyses; associations were attenuated but significant in biometric analyses (Ps < 0.05). Walkability was not associated with BMI, however, was associated with walking (but not MVPA) in both phenotypic and biometric analyses (Ps < 0.05), with no attenuation accounting for shared genetic and environmental background. Conclusions The association between activity and BMI is largely due to shared genetic and environmental factors, but a significant causal relationship remains accounting for shared background. Although walkability is not associated with BMI, it is associated with neighborhood walking (but not MVPA) accounting for shared background, suggesting a causal relationship between them. PMID:25482422

  7. Neighborhoods and Neighborhood Centers. Appendix.

    ERIC Educational Resources Information Center

    Herrick, Mary; And Others

    The first seven essays discuss the rise of community schools in urban public education, neighborhood health centers, churches in the inner city, cooperatives and credit unions in low income urban areas, job training and placement in neighborhood based programs, employment and supervision of nonprofessionals, urban observatories, and social…

  8. How Much Neighborhood Parks Contribute to Local Residents’ Physical Activity in the City of Los Angeles: a Meta-Analysis

    PubMed Central

    Cohen, Deborah A.; Derose, Kathryn Pitkin; Marsh, Terry; Williamson, Stephanie; Raaen, Laura

    2014-01-01

    Objective To quantify the contribution of neighborhood parks to population-level, moderate-to-vigorous physical activity (MVPA). Method We studied park use in 83 neighborhood parks in Los Angeles between 2003 and 2014 using systematic observation and surveys of park users and local residents. We observed park use at least 3–4 times per day over 4–7 clement days. We conducted a meta-analysis to estimate total, age group and gender-specific park use and total MVPA time in parks. Results An average park measuring 10 acres and with 40,000 local residents in a one-mile radius accrued 5,301 hours of use (SE=1,083) during one week, with 35% (1,850 hours) spent in MVPA and 12% (635 hours) spent in vigorous physical activity (VPA). As much as a 10.7-fold difference in weekly MVPA hours was estimated across study parks. Parks’ main contribution to population-level MVPA is for males, teenagers, and residents living within a half mile. Conclusion Neighborhood parks contribute substantially to population MVPA. The contribution may depend less on size and facilities than on “demand goods” – programming and activities--that draw users to a park. PMID:25199733

  9. Shape from equal thickness contours

    SciTech Connect

    Cong, G.; Parvin, B.

    1998-05-10

    A unique imaging modality based on Equal Thickness Contours (ETC) has introduced a new opportunity for 3D shape reconstruction from multiple views. We present a computational framework for representing each view of an object in terms of its object thickness, and then integrating these representations into a 3D surface by algebraic reconstruction. The object thickness is inferred by grouping curve segments that correspond to points of second derivative maxima. At each step of the process, we use some form of regularization to ensure closeness to the original features, as well as neighborhood continuity. We apply our approach to images of a sub-micron crystal structure obtained through a holographic process.

  10. Reprogramming the Chemodiversity of Terpenoid Cyclization by Remolding the Active Site Contour of epi-Isozizaene Synthase

    PubMed Central

    2015-01-01

    The class I terpenoid cyclase epi-isozizaene synthase (EIZS) utilizes the universal achiral isoprenoid substrate, farnesyl diphosphate, to generate epi-isozizaene as the predominant sesquiterpene cyclization product and at least five minor sesquiterpene products, making EIZS an ideal platform for the exploration of fidelity and promiscuity in a terpenoid cyclization reaction. The hydrophobic active site contour of EIZS serves as a template that enforces a single substrate conformation, and chaperones subsequently formed carbocation intermediates through a well-defined mechanistic sequence. Here, we have used the crystal structure of EIZS as a guide to systematically remold the hydrophobic active site contour in a library of 26 site-specific mutants. Remolded cyclization templates reprogram the reaction cascade not only by reproportioning products generated by the wild-type enzyme but also by generating completely new products of diverse structure. Specifically, we have tripled the overall number of characterized products generated by EIZS. Moreover, we have converted EIZS into six different sesquiterpene synthases: F96A EIZS is an (E)-β-farnesene synthase, F96W EIZS is a zizaene synthase, F95H EIZS is a β-curcumene synthase, F95M EIZS is a β-acoradiene synthase, F198L EIZS is a β-cedrene synthase, and F96V EIZS and W203F EIZS are (Z)-γ-bisabolene synthases. Active site aromatic residues appear to be hot spots for reprogramming the cyclization cascade by manipulating the stability and conformation of critical carbocation intermediates. A majority of mutant enzymes exhibit only relatively modest 2–100-fold losses of catalytic activity, suggesting that residues responsible for triggering substrate ionization readily tolerate mutations deeper in the active site cavity. PMID:24517311

  11. Getting Middle-School Students up and Moving: What's the Role of School and Neighborhood Environments...and the Weather: Studying the Effect of Neighborhood and School Environments on Youth Physical Activity Levels. Program Results

    ERIC Educational Resources Information Center

    Nakashian, Mary

    2008-01-01

    Researchers at the Harvard Prevention Research Center at Harvard University School of Public Health examined how physical and social environments of schools and neighborhoods shape routine physical activities of students attending 10 middle schools in the Boston area. They also analyzed the effect of weather conditions on student physical…

  12. Association Between the Built Environment in School Neighborhoods With Physical Activity Among New York City Children, 2012

    PubMed Central

    Gray, Heewon Lee; Quinn, James; Rundle, Andrew G.; Contento, Isobel R.; Koch, Pamela A.

    2016-01-01

    Introduction The benefits of physical activity for health and well-being are well established, yet built environment characteristics in the school neighborhood may constrain students’ ability to engage in physical activity and contribute to the considerable variation in physical activity among students at different schools. Methods Baseline data from the Food, Health and Choices obesity prevention trial were used to create multilevel linear models of the relationship between fifth-grade students’ (n = 952) physical activity and related psychosocial factors and characteristics of the built environment of the school’s neighborhood (park access, public transportation density, total crime, and walkability), controlling for age and body mass index z scores. Results Total crime was inversely associated with boys’ light physical activity duration (β = −0.189; P = .02) and behavioral intention for physical activity (β = −0.178; P = .03). Boys’ habit strength for physical activity was positively associated with public transportation density (β = 0.375; P = .02) and negatively associated with total crime (β = −0.216; P = .01), explaining 67% of between-school variation. Girls’ frequency of light physical activity was positively associated with park access (β = 0.188; P = .04). Built environment characteristics explained 97% of the between-school variation in girls’ self-efficacy in walking for exercise. Conclusions Characteristics of the built environment surrounding schools were associated with and explain between-school variation in students’ physical activity and several theory-based psychosocial factors. Partnerships between public health practitioners, policy makers, and school administrators may be warranted to shape the school neighborhood, specifically to decrease crime rates and increase park access, to encourage physical activity in youth. PMID:27536902

  13. Combined measure of neighborhood food and physical activity environments and weight-related outcomes: the CARDIA Study

    PubMed Central

    Meyer, Katie A.; Boone-Heinonen, Janne; Duffey, Kiyah J.; Rodriguez, Daniel A.; Kiefe, Catarina I.; Lewis, Cora E.; Gordon-Larsen, Penny

    2015-01-01

    Engagement in healthy lifestyle behaviors likely reflects access to a diverse and synergistic set of food and physical activity resources, yet most research examines discrete characteristics. We characterized neighborhoods with respect to their composition of features, and quantified associations with diet, physical activity (PA), body mass index (BMI), and insulin resistance (IR) in a longitudinal biracial cohort (n=4,143; aged 25–37; 1992–2006). We used latent class analysis to derive population-density-specific (< vs. ≥1,750 people per sq km) clusters of neighborhood indicators: road connectivity, parks and PA facilities, and food stores/restaurants. In lower population density areas, a latent class with higher food and PA resource diversity (relative to other clusters) was significantly associated with higher diet quality. In higher population density areas, a cluster with relatively more natural food/specialty stores; fewer convenience stores; and more PA resources was associated with higher diet quality. Neighborhood clusters were inconsistently associated with BMI and IR, and not associated with fast food consumption, walking, biking, or running. PMID:25723792

  14. Combined measure of neighborhood food and physical activity environments and weight-related outcomes: The CARDIA study.

    PubMed

    Meyer, Katie A; Boone-Heinonen, Janne; Duffey, Kiyah J; Rodriguez, Daniel A; Kiefe, Catarina I; Lewis, Cora E; Gordon-Larsen, Penny

    2015-05-01

    Engagement in healthy lifestyle behaviors likely reflects access to a diverse and synergistic set of food and physical activity resources, yet most research examines discrete characteristics. We characterized neighborhoods with respect to their composition of features, and quantified associations with diet, physical activity (PA), body mass index (BMI), and insulin resistance (IR) in a longitudinal biracial cohort (n=4143; aged 25-37; 1992-2006). We used latent class analysis to derive population-density-specific (neighborhood indicators: road connectivity, parks and PA facilities, and food stores/restaurants. In lower population density areas, a latent class with higher food and PA resource diversity (relative to other clusters) was significantly associated with higher diet quality. In higher population density areas, a cluster with relatively more natural food/specialty stores; fewer convenience stores; and more PA resources was associated with higher diet quality. Neighborhood clusters were inconsistently associated with BMI and IR, and not associated with fast food consumption, walking, biking, or running. PMID:25723792

  15. Understanding Neighborhood Environment Related to Hong Kong Children’s Physical Activity: A Qualitative Study Using Nominal Group Technique

    PubMed Central

    He, Gang; Cerin, Ester; Huang, Wendy Y.; Wong, Stephen H.

    2014-01-01

    Background Relationships between the neighborhood environment and children’s physical activity have been well documented in Western countries but are less investigated in ultra-dense Asian cities. The aim of this study was to identify the environmental facilitators and barriers of physical activity behaviors among Hong Kong Chinese children using nominal group technique. Methods Five nominal groups were conducted among 34 children aged 10–11 years from four types of neighborhoods varying in socio-economic status and walkability in Hong Kong. Environmental factors were generated by children in response to the question “What neighborhood environments do you think would increase or decrease your willingness to do physical activity?” Factors were prioritized in order of their importance to children’s physical activity. Results Sixteen unique environmental factors, which were perceived as the most important to children’s physical activity, were identified. Factors perceived as physical activity-facilitators included “Sufficient lighting”, “Bridge or tunnel”, “Few cars on roads”, “Convenient transportation”, “Subway station”, “Recreation grounds”, “Shopping malls with air conditioning”, “Fresh air”, “Interesting animals”, and “Perfume shop”. Factors perceived as physical activity-barriers included “People who make me feel unsafe”, “Crimes nearby”, “Afraid of being taken or hurt at night”, “Hard to find toilet in shopping mall”, “Too much noise”, and “Too many people in recreation grounds”. Conclusions Specific physical activity-related environmental facilitators and barriers, which are unique in an ultra-dense city, were identified by Hong Kong children. These initial findings can inform future examinations of the physical activity-environment relationship among children in Hong Kong and similar Asian cities. PMID:25187960

  16. Computer-aided diagnosis of pulmonary nodules on CT scans: Segmentation and classification using 3D active contours

    PubMed Central

    Way, Ted W.; Hadjiiski, Lubomir M.; Sahiner, Berkman; Chan, Heang-Ping; Cascade, Philip N.; Kazerooni, Ella A.; Bogot, Naama; Zhou, Chuan

    2009-01-01

    We are developing a computer-aided diagnosis (CAD) system to classify malignant and benign lung nodules found on CT scans. A fully automated system was designed to segment the nodule from its surrounding structured background in a local volume of interest (VOI) and to extract image features for classification. Image segmentation was performed with a three-dimensional (3D) active contour (AC) method. A data set of 96 lung nodules (44 malignant, 52 benign) from 58 patients was used in this study. The 3D AC model is based on two-dimensional AC with the addition of three new energy components to take advantage of 3D information: (1) 3D gradient, which guides the active contour to seek the object surface, (2) 3D curvature, which imposes a smoothness constraint in the z direction, and (3) mask energy, which penalizes contours that grow beyond the pleura or thoracic wall. The search for the best energy weights in the 3D AC model was guided by a simplex optimization method. Morphological and gray-level features were extracted from the segmented nodule. The rubber band straightening transform (RBST) was applied to the shell of voxels surrounding the nodule. Texture features based on run-length statistics were extracted from the RBST image. A linear discriminant analysis classifier with stepwise feature selection was designed using a second simplex optimization to select the most effective features. Leave-one-case-out resampling was used to train and test the CAD system. The system achieved a test area under the receiver operating characteristic curve (Az) of 0.83±0.04. Our preliminary results indicate that use of the 3D AC model and the 3D texture features surrounding the nodule is a promising approach to the segmentation and classification of lung nodules with CAD. The segmentation performance of the 3D AC model trained with our data set was evaluated with 23 nodules available in the Lung Image Database Consortium (LIDC). The lung nodule volumes segmented by the 3D AC

  17. Segmentation of follicular regions on H&E slides using a matching filter and active contour model

    NASA Astrophysics Data System (ADS)

    Belkacem-Boussaid, Kamel; Prescott, Jeffrey; Lozanski, Gerard; Gurcan, Metin N.

    2010-03-01

    Follicular Lymphoma (FL) accounts for 20-25% of non-Hodgkin lymphomas in the United States. The first step in follicular lymphoma grading is the identification of follicles. The goal of this paper is to develop a technique to segment follicular regions in H&E stained images. The method is based on a robust active contour model, which is initialized by a seed point selected inside the follicle manually by the user. The novel aspect of this method is the introduction of a matched filter for the flattening of background in the L channel of the Lab color space. The performance of the algorithm was tested by comparing it against the manual segmentations of trained readers using the Zijbendos similarity index. The mean accuracy of the final segmentation compared to the manual ground truth was 0.71 with a standard deviation of 0.12.

  18. A new background distribution-based active contour model for three-dimensional lesion segmentation in breast DCE-MRI

    SciTech Connect

    Liu, Hui; Liu, Yiping; Qiu, Tianshuang; Zhao, Zuowei; Zhang, Lina

    2014-08-15

    Purpose: To develop and evaluate a computerized semiautomatic segmentation method for accurate extraction of three-dimensional lesions from dynamic contrast-enhanced magnetic resonance images (DCE-MRIs) of the breast. Methods: The authors propose a new background distribution-based active contour model using level set (BDACMLS) to segment lesions in breast DCE-MRIs. The method starts with manual selection of a region of interest (ROI) that contains the entire lesion in a single slice where the lesion is enhanced. Then the lesion volume from the volume data of interest, which is captured automatically, is separated. The core idea of BDACMLS is a new signed pressure function which is based solely on the intensity distribution combined with pathophysiological basis. To compare the algorithm results, two experienced radiologists delineated all lesions jointly to obtain the ground truth. In addition, results generated by other different methods based on level set (LS) are also compared with the authors’ method. Finally, the performance of the proposed method is evaluated by several region-based metrics such as the overlap ratio. Results: Forty-two studies with 46 lesions that contain 29 benign and 17 malignant lesions are evaluated. The dataset includes various typical pathologies of the breast such as invasive ductal carcinoma, ductal carcinomain situ, scar carcinoma, phyllodes tumor, breast cysts, fibroadenoma, etc. The overlap ratio for BDACMLS with respect to manual segmentation is 79.55% ± 12.60% (mean ± s.d.). Conclusions: A new active contour model method has been developed and shown to successfully segment breast DCE-MRI three-dimensional lesions. The results from this model correspond more closely to manual segmentation, solve the weak-edge-passed problem, and improve the robustness in segmenting different lesions.

  19. If we build it, we will come: a model for community-led change to transform neighborhood conditions to support healthy eating and active living.

    PubMed

    Gavin, Vedette R; Seeholzer, Eileen L; Leon, Janeen B; Chappelle, Sandra Byrd; Sehgal, Ashwini R

    2015-06-01

    Neighborhoods affect health. In 3 adjoining inner-city Cleveland, Ohio, neighborhoods, residents have an average life expectancy 15 years less than that of a nearby suburb. To address this disparity, a local health funder created the 2010 to 2013 Francis H. Beam Community Health Fellowship to develop a strategic community engagement process to establish a Healthy Eating & Active Living (HEAL) culture and lifestyle in the neighborhoods. The fellow developed and advanced a model, engaging the community in establishing HEAL options and culture. Residents used the model to identify a shared vision for HEAL and collaborated with community partners to create and sustain innovative HEAL opportunities. This community-led, collaborative model produced high engagement levels (15% of targeted 12 000 residents) and tangible improvements in the neighborhood's physical, resource, and social environments. PMID:25880943

  20. If We Build It, We Will Come: A Model for Community-Led Change to Transform Neighborhood Conditions to Support Healthy Eating and Active Living

    PubMed Central

    Gavin, Vedette R.; Seeholzer, Eileen L.; Leon, Janeen B.; Chappelle, Sandra Byrd; Sehgal, Ashwini R.

    2015-01-01

    Neighborhoods impact health. In three adjoining inner-city Cleveland neighborhoods, residents have an average life expectancy 15 years less than that of a nearby suburb.1 To address this disparity a local health funder created a Fellowship to develop a strategic community engagement process to establish a Healthy Eating and Active Living (HEAL) culture and lifestyle in the neighborhoods. The Fellow developed and advanced a model, engaging the community in establishing HEAL options and culture. Using the model, residents identified a shared vision for HEAL and collaborated with community partners to create and sustain innovative HEAL opportunities. This community-led, collaborative model produced high engagement levels (15% of targeted 12,000 residents) and tangible improvements in the neighborhood's physical, resource, and social environments. PMID:25880943

  1. [Effects of neighborhood collective efficacy and violence on antisocial behavior: dual mediation of socialization and routine activities].

    PubMed

    Yoshizawa, Hiroyuki; Yoshida, Toshikazu; Harada, Chika; Unagami, Tomoaki; Park, Hyun-Jung; Nakajima, Makoto; Ozeki, Miki

    2009-04-01

    The authors examined the effects of neighborhood collective efficacy and violence on adolescents' antisocial behavior tendencies by means of the dual mediation of socialization indices (i.e., social information-processing and self regulation) and routine activities. Collective efficacy and violence exposure were assessed by neighborhood "informal social control" and "social cohesion and trust" during the elementary and junior high school years, and the frequency of violence in the community during junior high and high school years. Normative beliefs about aggression, cognitive distortions, social rule appropriateness and self regulation were used to assess both the positive and negative indices of socialization. Routine activities were assessed by the experience in unstructured socializing activities. Antisocial tendencies were assessed by evaluations of the seriousness and past experience of delinquent behaviors. The results of structural equation modeling revealed that the effect of collective efficacy on antisocial tendencies was perfectly mediated by the socialization indices, whereas experienced violence was partly mediated by routine activities. Possible improvements of this dual mediation model were discussed. PMID:19489428

  2. "Neighborhood matters": assessment of neighborhood social processes.

    PubMed

    Henry, David; Gorman-Smith, Deborah; Schoeny, Michael; Tolan, Patrick

    2014-12-01

    Neighborhoods are important contexts for understanding development and behavior, but cost and difficulty have challenged attempts to develop measures of neighborhood social processes at the neighborhood level. This article reports the development, reliability, and validity of Neighborhood Matters, a collection of instruments assessing three aspects of neighborhood social processes, namely, norms (five subscales), informal social control (six subscales and total scale), social connection (two subscales), as well as individual scales for assessing neighborhood change, neighborhood resources, and neighborhood problems. Six hundred six residents of Chicago, chosen at random from 30 neighborhoods (defined by US Census tracts), completed the measures. Neighborhoods were selected randomly from pools that balanced poverty and predominant (African-American vs. Latino Hispanic) ethnicity. Within each neighborhood 20 individuals were selected at random, balanced by age (18-24 vs. 30+) and gender. Scaling and item analysis permitted reduction of the number of items in each scale. All subscales had individual-level internal consistency in excess of .7. Generalizability theory analysis using random effects regression models found significant shared variance at the neighborhood level for three norms subscales, four informal social control subscales, both social connection subscales, and the neighborhood change, resources and problems scales. Validity analyses found significant associations between neighborhood-level scores on multiple Neighborhood Matters scales and neighborhood levels of violent, property, and drug-related crime. Discussion focuses on potential applications of the Neighborhood Matters scales in community research. PMID:25287739

  3. Cost-effectiveness of a tuberculosis active case finding program targeting household and neighborhood contacts in Cambodia.

    PubMed

    Yadav, Rajendra P; Nishikiori, Nobuyuki; Satha, Peou; Eang, Mao T; Lubell, Yoel

    2014-05-01

    In many high-risk populations, access to tuberculosis (TB) diagnosis and treatment is limited and pockets of high prevalence persist. We estimated the cost-effectiveness of an extensive active case finding program in areas of Cambodia where TB notifications and household poverty rates are highest and access to care is restricted. Thirty operational health districts with high TB incidence and household poverty were randomized into intervention and control groups. In intervention operational health districts, all household and symptomatic neighborhood contacts of registered TB patients of the past two years were encouraged to attend screening at mobile centers. In control districts, routine passive case finding activities continued. The program screened more than 35,000 household and neighborhood contacts and identified 810 bacteriologically confirmed cases. The cost-effectiveness analysis estimated that in these cases the reduction in mortality from 14% to 2% would result in a cost per daily adjusted life year averted of $330, suggesting that active case finding was highly cost-effective. PMID:24615134

  4. pSnakes: a new radial active contour model and its application in the segmentation of the left ventricle from echocardiographic images.

    PubMed

    de Alexandria, Auzuir Ripardo; Cortez, Paulo César; Bessa, Jessyca Almeida; da Silva Félix, John Hebert; de Abreu, José Sebastião; de Albuquerque, Victor Hugo C

    2014-10-01

    Active contours are image segmentation methods that minimize the total energy of the contour to be segmented. Among the active contour methods, the radial methods have lower computational complexity and can be applied in real time. This work aims to present a new radial active contour technique, called pSnakes, using the 1D Hilbert transform as external energy. The pSnakes method is based on the fact that the beams in ultrasound equipment diverge from a single point of the probe, thus enabling the use of polar coordinates in the segmentation. The control points or nodes of the active contour are obtained in pairs and are called twin nodes. The internal energies as well as the external one, Hilbertian energy, are redefined. The results showed that pSnakes can be used in image segmentation of short-axis echocardiogram images and that they were effective in image segmentation of the left ventricle. The echo-cardiologist's golden standard showed that the pSnakes was the best method when compared with other methods. The main contributions of this work are the use of pSnakes and Hilbertian energy, as the external energy, in image segmentation. The Hilbertian energy is calculated by the 1D Hilbert transform. Compared with traditional methods, the pSnakes method is more suitable for ultrasound images because it is not affected by variations in image contrast, such as noise. The experimental results obtained by the left ventricle segmentation of echocardiographic images demonstrated the advantages of the proposed model. The results presented in this paper are justified due to an improved performance of the Hilbert energy in the presence of speckle noise. PMID:24957548

  5. Constraint factor graph cut–based active contour method for automated cellular image segmentation in RNAi screening

    PubMed Central

    CHEN, C.; LI, H.; ZHOU, X.; WONG, S. T. C.

    2010-01-01

    Summary Image-based, high throughput genome-wide RNA interference (RNAi) experiments are increasingly carried out to facilitate the understanding of gene functions in intricate biological processes. Automated screening of such experiments generates a large number of images with great variations in image quality, which makes manual analysis unreasonably time-consuming. Therefore, effective techniques for automatic image analysis are urgently needed, in which segmentation is one of the most important steps. This paper proposes a fully automatic method for cells segmentation in genome-wide RNAi screening images. The method consists of two steps: nuclei and cytoplasm segmentation. Nuclei are extracted and labelled to initialize cytoplasm segmentation. Since the quality of RNAi image is rather poor, a novel scale-adaptive steerable filter is designed to enhance the image in order to extract long and thin protrusions on the spiky cells. Then, constraint factor GCBAC method and morphological algorithms are combined to be an integrated method to segment tight clustered cells. Compared with the results obtained by using seeded watershed and the ground truth, that is, manual labelling results by experts in RNAi screening data, our method achieves higher accuracy. Compared with active contour methods, our method consumes much less time. The positive results indicate that the proposed method can be applied in automatic image analysis of multi-channel image screening data. PMID:18445146

  6. Segmentation of solid subregion of high grade gliomas in MRI images based on active contour model (ACM)

    NASA Astrophysics Data System (ADS)

    Seow, P.; Win, M. T.; Wong, J. H. D.; Abdullah, N. A.; Ramli, N.

    2016-03-01

    Gliomas are tumours arising from the interstitial tissue of the brain which are heterogeneous, infiltrative and possess ill-defined borders. Tumour subregions (e.g. solid enhancing part, edema and necrosis) are often used for tumour characterisation. Tumour demarcation into substructures facilitates glioma staging and provides essential information. Manual segmentation had several drawbacks that include laborious, time consuming, subjected to intra and inter-rater variability and hindered by diversity in the appearance of tumour tissues. In this work, active contour model (ACM) was used to segment the solid enhancing subregion of the tumour. 2D brain image acquisition data using 3T MRI fast spoiled gradient echo sequence in post gadolinium of four histologically proven high-grade glioma patients were obtained. Preprocessing of the images which includes subtraction and skull stripping were performed and then followed by ACM segmentation. The results of the automatic segmentation method were compared against the manual delineation of the tumour by a trainee radiologist. Both results were further validated by an experienced neuroradiologist and a brief quantitative evaluations (pixel area and difference ratio) were performed. Preliminary results of the clinical data showed the potential of ACM model in the application of fast and large scale tumour segmentation in medical imaging.

  7. Myocardial Iron Loading Assessment by Automatic Left Ventricle Segmentation with Morphological Operations and Geodesic Active Contour on T2* images

    PubMed Central

    Luo, Yun-gang; Ko, Jacky KL; Shi, Lin; Guan, Yuefeng; Li, Linong; Qin, Jing; Heng, Pheng-Ann; Chu, Winnie CW; Wang, Defeng

    2015-01-01

    Myocardial iron loading thalassemia patients could be identified using T2* magnetic resonance images (MRI). To quantitatively assess cardiac iron loading, we proposed an effective algorithm to segment aligned free induction decay sequential myocardium images based on morphological operations and geodesic active contour (GAC). Nine patients with thalassemia major were recruited (10 male and 16 female) to undergo a thoracic MRI scan in the short axis view. Free induction decay images were registered for T2* mapping. The GAC were utilized to segment aligned MR images with a robust initialization. Segmented myocardium regions were divided into sectors for a region-based quantification of cardiac iron loading. Our proposed automatic segmentation approach achieve a true positive rate at 84.6% and false positive rate at 53.8%. The area difference between manual and automatic segmentation was 25.5% after 1000 iterations. Results from T2* analysis indicated that regions with intensity lower than 20 ms were suffered from heavy iron loading in thalassemia major patients. The proposed method benefited from abundant edge information of the free induction decay sequential MRI. Experiment results demonstrated that the proposed method is feasible in myocardium segmentation and was clinically applicable to measure myocardium iron loading. PMID:26215336

  8. Myocardial Iron Loading Assessment by Automatic Left Ventricle Segmentation with Morphological Operations and Geodesic Active Contour on T2* images

    NASA Astrophysics Data System (ADS)

    Luo, Yun-Gang; Ko, Jacky Kl; Shi, Lin; Guan, Yuefeng; Li, Linong; Qin, Jing; Heng, Pheng-Ann; Chu, Winnie Cw; Wang, Defeng

    2015-07-01

    Myocardial iron loading thalassemia patients could be identified using T2* magnetic resonance images (MRI). To quantitatively assess cardiac iron loading, we proposed an effective algorithm to segment aligned free induction decay sequential myocardium images based on morphological operations and geodesic active contour (GAC). Nine patients with thalassemia major were recruited (10 male and 16 female) to undergo a thoracic MRI scan in the short axis view. Free induction decay images were registered for T2* mapping. The GAC were utilized to segment aligned MR images with a robust initialization. Segmented myocardium regions were divided into sectors for a region-based quantification of cardiac iron loading. Our proposed automatic segmentation approach achieve a true positive rate at 84.6% and false positive rate at 53.8%. The area difference between manual and automatic segmentation was 25.5% after 1000 iterations. Results from T2* analysis indicated that regions with intensity lower than 20 ms were suffered from heavy iron loading in thalassemia major patients. The proposed method benefited from abundant edge information of the free induction decay sequential MRI. Experiment results demonstrated that the proposed method is feasible in myocardium segmentation and was clinically applicable to measure myocardium iron loading.

  9. Perceived and Objective Measures of Neighborhood Walkability and Physical Activity among Adults in Japan: A Multilevel Analysis of a Nationally Representative Sample

    PubMed Central

    Hanibuchi, Tomoya; Nakaya, Tomoki; Yonejima, Mayuko; Honjo, Kaori

    2015-01-01

    Although associations between a person’s neighborhood and their health have been studied internationally, most studies have been limited to a few cities or towns. Therefore, we used a nationally representative sample to explore whether perceived and objective neighborhood walkability was associated with the physical activity of residents. Data were analyzed from the Japanese General Social Surveys of 2010 (n = 2395; 1114 men and 1281 women). Perceived walkability was scored using factor analysis for the respondents’ perceptions of neighborhood conditions, while objective walkability was measured using the geographic information system approach. Finally, multilevel logistic regression analysis was performed to examine whether neighborhood walkability was associated with the frequency of leisure-time physical activity (LTPA) among respondents. We found that perceived walkability was positively associated with the frequency of LTPA (odds ratio of the highest quartile was 1.53 (1.14–2.05) compared with the lowest quartile); however, objective walkability showed no association. When stratified by gender, an association between perceived walkability and LTPA was observed among women, but only a marginally significant association was present between objective walkability and LTPA among men. We conclude that the association between neighborhood walkability and LTPA can be partially generalized across Japan. PMID:26512682

  10. Parental perceived neighborhood attributes: associations with active transport and physical activity among 10–12 year old children and the mediating role of independent mobility

    PubMed Central

    2014-01-01

    Background During the last decades, the use of active travel modes declined in all age groups. Childhood is a critical time to establish lifelong healthy patterns. To develop effective interventions in this age group, insight in the correlates of health behaviors and the possible mediating factors is necessary. Among children, the role of parents may not be overlooked. Therefore, this study aimed to examine the associations of parental perceptions of neighborhood environmental attributes with active transport and total physical activity in 10–12 year old Belgian boys and girls. Furthermore, this study examined the potential mediating effect of independent mobility on these associations. Methods In the present study, 736 10–12 year old children and their parents from 44 elementary schools in Flanders, Belgium, participated. The children were asked to wear an activity monitor and to fill in a survey questioning demographic factors and the Flemish Physical Activity Questionnaire. The parents filled in a survey concerning demographic factors, the child’s level of independent mobility and environmental perceptions (Neighborhood Environmental Walkability Scale). Results Overall, boys reported more active transport when parents perceived more land use mix diversity, shorter distances to school, good land use mix access, higher residential density and less pleasing neighborhood aesthetics. Higher total physical activity levels were reported when parents perceived shorter distances to school and availability of walking/cycling infrastructure. None of the associations was mediated by independent mobility in boys. Girls reported more active transport when parents perceived higher residential density, more land use mix diversity, shorter distances to school, good land use mix access, available walking/cycling infrastructure and convenient recreational facilities. Girls reported higher total physical activity levels when parents perceived high residential density, good

  11. Cross-sectional association of the number of neighborhood facilities assessed using postal code with objectively measured physical activity: the Saku cohort study.

    PubMed

    Yasunaga, Akitomo; Murakami, Haruka; Morita, Akemi; Deura, Kijyo; Aiba, Naomi; Watanabe, Shaw; Miyachi, Motohiko

    2016-01-01

    Objectives The aim of this study was to examine the association between the number of neighborhood facilities that were assessed according to postal code and objectively measured physical activity by using an accelerometer in community-dwelling Japanese people.Methods The participants included 1,274 Japanese people aged 30-84 years from the Saku cohort study. As neighborhood facilities related to physical activity, we extracted information regarding train stations, supermarkets/convenience stores, postal offices/banks, hospitals/clinics, public offices/community centers, cultural facilities/public children's houses, parks, and sports facilities by using each participant's postal code from the online version of the iTownPages directory published by Nippon Telegraph and Telephone Corporation (NTT) and the official homepage of the Saku City Government Office. We measured each participant's physical activity level using an accelerometer, and calculated the average daily step count and the average weekly period of moderate-to-vigorous intensity (≥3 metabolic equivalents of tasks [METs]) physical activity. The association between two selected physical activity-related variables and the numbers of eight types of neighborhood facilities were analyzed by multivariate logistic regression analysis for people aged 30-64 years and for those aged over 65 years.Results On multivariate logistic regression analysis, meeting the 23 METs h/week of moderate-to-vigorous intensity physical activity was significantly and positively associated with the number of supermarkets/convenience stores in the neighborhood in both age groups. In addition, meeting the desired daily step count outlined in the Japanese National Health Promotion guidelines was positively related to the number of postal offices/banks for people aged over 65 years.Conclusion The results of this study suggest that a sufficient number of neighborhood facilities (i.e., stores, banks, and postal offices) is closely

  12. Computer-aided measurement of liver volumes in CT by means of geodesic active contour segmentation coupled with level-set algorithms

    SciTech Connect

    Suzuki, Kenji; Kohlbrenner, Ryan; Epstein, Mark L.; Obajuluwa, Ademola M.; Xu Jianwu; Hori, Masatoshi

    2010-05-15

    Purpose: Computerized liver extraction from hepatic CT images is challenging because the liver often abuts other organs of a similar density. The purpose of this study was to develop a computer-aided measurement of liver volumes in hepatic CT. Methods: The authors developed a computerized liver extraction scheme based on geodesic active contour segmentation coupled with level-set contour evolution. First, an anisotropic diffusion filter was applied to portal-venous-phase CT images for noise reduction while preserving the liver structure, followed by a scale-specific gradient magnitude filter to enhance the liver boundaries. Then, a nonlinear grayscale converter enhanced the contrast of the liver parenchyma. By using the liver-parenchyma-enhanced image as a speed function, a fast-marching level-set algorithm generated an initial contour that roughly estimated the liver shape. A geodesic active contour segmentation algorithm coupled with level-set contour evolution refined the initial contour to define the liver boundaries more precisely. The liver volume was then calculated using these refined boundaries. Hepatic CT scans of 15 prospective liver donors were obtained under a liver transplant protocol with a multidetector CT system. The liver volumes extracted by the computerized scheme were compared to those traced manually by a radiologist, used as ''gold standard.''Results: The mean liver volume obtained with our scheme was 1504 cc, whereas the mean gold standard manual volume was 1457 cc, resulting in a mean absolute difference of 105 cc (7.2%). The computer-estimated liver volumetrics agreed excellently with the gold-standard manual volumetrics (intraclass correlation coefficient was 0.95) with no statistically significant difference (F=0.77; p(F{<=}f)=0.32). The average accuracy, sensitivity, specificity, and percent volume error were 98.4%, 91.1%, 99.1%, and 7.2%, respectively. Computerized CT liver volumetry would require substantially less completion time

  13. Children's Perceptions of Their Home and Neighborhood Environments, and Their Association with Objectively Measured Physical Activity: A Qualitative and Quantitative Study

    ERIC Educational Resources Information Center

    Hume, C.; Salmon, J.; Ball, K.

    2005-01-01

    Environmental factors may have an important influence on children's physical activity, yet children's perspectives of their home and neighborhood environments have not been widely assessed. The aim of this study was to investigate children's perceptions of their environments, and to examine associations between these perceptions and objectively…

  14. Travel beyond the home neighborhood for delinquent behaviors: moderation of home neighborhood influences.

    PubMed

    Tompsett, Carolyn J; Amrhein, Kelly E; Hassan, Sarah

    2014-06-01

    Neighborhood research indicates that adolescents are at higher risk for delinquency when they reside in neighborhoods low in collective efficacy, low in perceived prosocial norms and values, and high in availability of substances and firearms. However, as adolescents develop, they are more likely to independently travel during their day-to-day activities, and the effects of their home neighborhood may be weakened as they spend time in other communities. The current study surveyed 179 adolescents involved in the juvenile justice system in a small Midwestern city on their perceptions of their home neighborhood and self-reported delinquency. While perceptions of several home neighborhood characteristics significantly predicted severity of delinquency for all respondents, neighborhood effects were significantly weaker for those adolescents who tended to engage in illegal behaviors outside their home neighborhood. These findings suggest that future research and prevention efforts should include more attention to how adolescents may be influenced by multiple neighborhoods. PMID:24793379

  15. Travel Beyond the Home Neighborhood for Delinquent Behaviors: Moderation of Home Neighborhood Influences

    PubMed Central

    Tompsett, Carolyn J.; Amrhein, Kelly E.; Hassan, Sarah

    2014-01-01

    Neighborhood research indicates that adolescents are at higher risk for delinquency when they reside in neighborhoods low in collective efficacy, low in perceived prosocial norms and values, and high in availability of substances and firearms. However, as adolescents develop, they are more likely to independently travel during their day-to-day activities, and the effects of their home neighborhood may be weakened as they spend time in other communities. The current study surveyed 179 adolescents involved in the juvenile justice system in a small Midwestern city on their perceptions of their home neighborhood and self-reported delinquency. While perceptions of several home neighborhood characteristics significantly predicted severity of delinquency for all respondents, neighborhood effects were significantly weaker for those adolescents who tended to engage in illegal behaviors outside their home neighborhood. These findings suggest that future research and prevention efforts should include more attention to how adolescents may be influenced by multiple neighborhoods. PMID:24793379

  16. Disentangling neighborhood contextual associations with child body mass index, diet, and physical activity: the role of built, socioeconomic, and social environments.

    PubMed

    Carroll-Scott, Amy; Gilstad-Hayden, Kathryn; Rosenthal, Lisa; Peters, Susan M; McCaslin, Catherine; Joyce, Rebecca; Ickovics, Jeannette R

    2013-10-01

    Obesity prevalence among US children and adolescents has tripled in the past three decades. Consequently, dramatic increases in chronic disease incidence are expected, particularly among populations already experiencing health disparities. Recent evidence identifies characteristics of "obesogenic" neighborhood environments that affect weight and weight-related behaviors. This study aimed to examine associations between built, socioeconomic, and social characteristics of a child's residential environment on body mass index (BMI), diet, and physical activity. We focused on pre-adolescent children living in New Haven, Connecticut to better understand neighborhood environments' contribution to persistent health disparities. Participants were 1048 fifth and sixth grade students who completed school-based health surveys and physical measures in fall 2009. Student data were linked to US Census, parks, retailer, and crime data. Analyses were conducted using multilevel modeling. Property crimes and living further from a grocery store were associated with higher BMI. Students living within a 5-min walk of a fast food outlet had higher BMI, and those living in a tract with higher density of fast food outlets reported less frequent healthy eating and more frequent unhealthy eating. Students' reported perceptions of access to parks, playgrounds, and gyms were associated with more frequent healthy eating and exercise. Students living in more affluent neighborhoods reported more frequent healthy eating, less unhealthy eating, and less screen time. Neighborhood social ties were positively associated with frequency of exercise. In conclusion, distinct domains of neighborhood environment characteristics were independently related to children's BMI and health behaviors. Findings link healthy behaviors with built, social, and socioeconomic environment assets (access to parks, social ties, affluence), and unhealthy behaviors with built environment inhibitors (access to fast food

  17. Distributed Contour Trees

    SciTech Connect

    Morozov, Dmitriy; Weber, Gunther H.

    2014-03-31

    Topological techniques provide robust tools for data analysis. They are used, for example, for feature extraction, for data de-noising, and for comparison of data sets. This chapter concerns contour trees, a topological descriptor that records the connectivity of the isosurfaces of scalar functions. These trees are fundamental to analysis and visualization of physical phenomena modeled by real-valued measurements. We study the parallel analysis of contour trees. After describing a particular representation of a contour tree, called local{global representation, we illustrate how di erent problems that rely on contour trees can be solved in parallel with minimal communication.

  18. Nuclear Neighborhoods and Gene Expression

    PubMed Central

    Zhao, Rui; Bodnar, Megan S.; Spector, David L.

    2009-01-01

    Summary The eukaryotic nucleus is a highly compartmentalized and dynamic environment. Chromosome territories are arranged non-randomly within the nucleus and numerous studies have indicated that a gene’s position in the nucleus can impact its transcriptional activity. Here, we focus on recent advances in our understanding of the influence of specific nuclear neighborhoods on gene expression or repression. Nuclear neighborhoods associated with transcriptional repression include the inner nuclear membrane/nuclear lamina and peri-nucleolar chromatin, whereas neighborhoods surrounding the nuclear pore complex, PML nuclear bodies, and nuclear speckles seem to be transcriptionally permissive. While nuclear position appears to play an important role in gene expression, it is likely to be only one piece of a flexible puzzle that incorporates numerous parameters. We are still at a very early, yet exciting stage in our journey toward deciphering the mechanism(s) that govern the permissiveness of gene expression/repression within different nuclear neighborhoods. PMID:19339170

  19. Automatic segmentation of head and neck CT images for radiotherapy treatment planning using multiple atlases, statistical appearance models, and geodesic active contours

    SciTech Connect

    Fritscher, Karl D. Sharp, Gregory; Peroni, Marta; Zaffino, Paolo; Spadea, Maria Francesca; Schubert, Rainer

    2014-05-15

    Purpose: Accurate delineation of organs at risk (OARs) is a precondition for intensity modulated radiation therapy. However, manual delineation of OARs is time consuming and prone to high interobserver variability. Because of image artifacts and low image contrast between different structures, however, the number of available approaches for autosegmentation of structures in the head-neck area is still rather low. In this project, a new approach for automated segmentation of head-neck CT images that combine the robustness of multiatlas-based segmentation with the flexibility of geodesic active contours and the prior knowledge provided by statistical appearance models is presented. Methods: The presented approach is using an atlas-based segmentation approach in combination with label fusion in order to initialize a segmentation pipeline that is based on using statistical appearance models and geodesic active contours. An anatomically correct approximation of the segmentation result provided by atlas-based segmentation acts as a starting point for an iterative refinement of this approximation. The final segmentation result is based on using model to image registration and geodesic active contours, which are mutually influencing each other. Results: 18 CT images in combination with manually segmented labels of parotid glands and brainstem were used in a leave-one-out cross validation scheme in order to evaluate the presented approach. For this purpose, 50 different statistical appearance models have been created and used for segmentation. Dice coefficient (DC), mean absolute distance and max. Hausdorff distance between the autosegmentation results and expert segmentations were calculated. An average Dice coefficient of DC = 0.81 (right parotid gland), DC = 0.84 (left parotid gland), and DC = 0.86 (brainstem) could be achieved. Conclusions: The presented framework provides accurate segmentation results for three important structures in the head neck area. Compared to a

  20. Contouring Trivariate Data

    NASA Technical Reports Server (NTRS)

    Stead, S. E.; Makatura, G. T.

    1985-01-01

    In many applications, the data consist of discrete 3-D points at which one or more parameters are given. To display contours, the data are represented by a continuous function which is evaluated at any point as needed for contouring. Contouring results are presented which are applicable both to artitrarily spaced data and to data which lie on a topologically rectangular three dimensional grid. the contours are assumed to be described by 3-D display lists for viewing on a dynamic color graphics device; that is, they will not simply be projected into 2-D and viewed as a static image on a frame buffer. Dynamic viewing of color contours may be essential to the proper interpretation of results. The gridded data lie on a topologically rectangular grid although two or more nodes may be the same point. Parametric tensor product methods may be used to fit the gridded data and to generate the contours. Rectangular elements are convenient but not necessary. For example, there are other methods which are effective for contouring over tetrahedral elements.

  1. Male Body Contouring.

    PubMed

    Singh, Babu; Keaney, Terrence; Rossi, Anthony M

    2015-09-01

    Men are increasingly turning to dermatologists and plastic surgeons to request procedures that correct or enhance physical features. With the advent of this emerging new patient population, alterations in preexisting aesthetic techniques, gender-specific uses of existing devices and overall approaches need to be revisited and adapted to obtain results that are suitable for the male patient. Recently, body contouring has become one of the most sought out procedures by men. Although the majority of clinical studies involving body contouring esthetics are performed with female patients, gains from such studies can be extrapolated to men. Body contouring can be broadly classified as non-invasive or invasive, depending on the modality used. Non-invasive contouring is most frequently performed with devices that target subcutaneous adipose with focused electrical or thermal energy, including low-level laser, cryolipolysis, ultrasonography, and radiofrequency. Invasive body contouring modalities useful for male body contouring include liposuction, pectoral and abdominal wall etching, jawline fillers, synthetic deoxycholic acid injections, and solid silicone implants. The purpose of this review is to bring attention to the unique aspects, strategies, and modalities used in aesthetic body contouring for the male patient. PMID:26355627

  2. Modeling robot contour processes

    NASA Astrophysics Data System (ADS)

    Whitney, D. E.; Edsall, A. C.

    Robot contour processes include those with contact force like car body grinding or deburring of complex castings, as well as those with little or no contact force like inspection. This paper describes ways of characterizing, identifying, and estimating contours and robot trajectories. Contour and robot are modeled as stochastic processes in order to emphasize that both successive robot cycles and successive industrial workpieces are similar but not exactly the same. The stochastic models can be used to identify the state of a workpiece or process, or to design a filter to estimate workpiece, shape and robot position from robot-based measurements.

  3. Using MapMyFitness to Place Physical Activity into Neighborhood Context

    PubMed Central

    Hirsch, Jana A.; James, Peter; Robinson, Jamaica R. M.; Eastman, Kyler M.; Conley, Kevin D.; Evenson, Kelly R.; Laden, Francine

    2014-01-01

    It is difficult to obtain detailed information on the context of physical activity at large geographic scales, such as the entire United States, as well as over long periods of time, such as over years. MapMyFitness is a suite of interactive tools for individuals to track their workouts online or using global positioning system in their phones or other wireless trackers. This method article discusses the use of physical activity data tracked using MapMyFitness to examine patterns over space and time. An overview of MapMyFitness, including data tracked, user information, and geographic scope, is explored. We illustrate the utility of MapMyFitness data using tracked physical activity by users in Winston-Salem, NC, USA between 2006 and 2013. Types of physical activities tracked are described, as well as the percent of activities occurring in parks. Strengths of MapMyFitness data include objective data collection, low participant burden, extensive geographic scale, and longitudinal series. Limitations include generalizability, behavioral change as the result of technology use, and potential ethical considerations. MapMyFitness is a powerful tool to investigate patterns of physical activity across large geographic and temporal scales. PMID:24653982

  4. Neighborhood level health risk assessment of lead paint removal activities from elevated steel bridges

    SciTech Connect

    Conway, R.F.; Cohen, J.T.; Bowers, T.

    1999-07-01

    The New York City Department of Transportation (NYCDOT) has adopted strict containment and monitoring procedures during paint removal activities on its bridges because of the increasing awareness about lead poisoning in children in urban environments and the potential risk of lead-based paint releases during those activities. NYCDOT owns nearly 800 bridges scattered throughout New York City. Before undertaking paint removal activities as part of its ongoing preventive maintenance and rehabilitation program, NYCDOT recently conducted an analysis to determine the public health risk posed to children living near them. The analysis the first of its kind to assess the actual public health risk potential during both routine operations and upset conditions, or accidental releases evaluated the total and incremental blood lead levels from paint removal activities on more than 5,000 children from 6 months to 6 years old. Increases in baseline blood lead levels were estimated using several models, including EPA's Integrated Exposure Uptake Biokinetic (IEUBK) Model. This model estimates steady-state blood lead levels in children, reflecting exposure to lead in multiple media over an extended period of time. Increases in lead exposure from paint removal activities in the area surrounding the bridges was estimated using EPA's Industrial Source Complex (ISC3) model to calculate ambient air and deposition levels. Potential releases from the containment and ancillary equipment used in the paint removal process were modeled based on different release scenarios ranging from routine operations to complete failure of containment. To estimate the paint removal activities' contribution to long-term exterior dust lead levels (and its related interior component), a stochastic simulation model was developed for each block in the study area.

  5. The Use of Kernel Density Estimation to Examine Associations between Neighborhood Destination Intensity and Walking and Physical Activity

    PubMed Central

    King, Tania L.; Thornton, Lukar E.; Bentley, Rebecca J.; Kavanagh, Anne M.

    2015-01-01

    in areas of greater destination intensity walked more frequently, and showed higher odds of being sufficiently physically active–an effect that was largely explained by levels of walking. The results suggest that increasing the intensity of destinations in areas where they are more dispersed; and or planning neighborhoods with greater destination intensity, may increase residents’ likelihood of being sufficiently active for health. PMID:26355848

  6. Children's Active Free Play in Local Neighborhoods: A Behavioral Mapping Study

    ERIC Educational Resources Information Center

    Veitch, J.; Salmon, J.; Ball, K.

    2008-01-01

    Many Australian children are more sedentary than they should be, and almost one in five are currently overweight or obese. Some children may face difficulties finding opportunities to be active, having poor access to safe public open spaces or having low independent mobility limiting their access to places to play. This study aimed to examine…

  7. Variable contour securing system

    NASA Technical Reports Server (NTRS)

    Zebus, P. P.; Packer, P. N.; Haynie, C. C. (Inventor)

    1978-01-01

    A variable contour securing system has a retaining structure for a member whose surface contains a variable contour. The retaining mechanism includes a spaced array of adjustable spindles mounted on a housing. Each spindle has a base member support cup at one end. A vacuum source is applied to the cups for seating the member adjacent to the cups. A locking mechanism sets the spindles in a predetermined position once the member has been secured to the spindle support cups.

  8. Perceived and Objective Measures of Neighborhood Environment for Physical Activity Among Mexican Adults, 2011

    PubMed Central

    Salvo, Deborah; Lamadrid-Figueroa, Héctor; Hernández, Bernardo; Rivera-Dommarco, Juan A.; Pratt, Michael

    2016-01-01

    Introduction Environmental supports for physical activity may help residents to be physically active. However, such supports might not help if residents’ perceptions of the built environment do not correspond with objective measures. We assessed the associations between objective and perceived measures of the built environment among adults in Cuernavaca, Mexico, and examined whether certain variables modified this relationship. Methods We conducted a population-based (n = 645) study in 2011 that used objective (based on geographic information systems) and perceived (by questionnaire) measures of the following features of the built environment: residential density, mixed-land use, intersection density, and proximity to parks and transit stops. We used linear regression to assess the adjusted associations between these measures and to identify variables modifying these relationships. Results Adjusted associations were significant for all features (P < .05) except intersection density and proximity to transit stops. Significantly stronger associations between perceived and objective measures were observed among participants with low socioeconomic status, participants who did not own a motor vehicle or did not meet physical activity recommendations, and participants perceiving parks as safe. Conclusion Perceived measures of residential density, mixed-land use, and proximity to parks are associated with objective environmental measures related to physical activity. However, in Mexico, it should not be assumed that perceived measures of intersection density and proximity to transit stops are the same as objective measures. Our results are consistent with those from high-income countries in that associations between perceived and objective measures are modified by individual sociodemographic and psychosocial factors. PMID:27281391

  9. Reconstruction of surfaces from planar contours through contour interpolation

    NASA Astrophysics Data System (ADS)

    Sunderland, Kyle; Woo, Boyeong; Pinter, Csaba; Fichtinger, Gabor

    2015-03-01

    Segmented structures such as targets or organs at risk are typically stored as 2D contours contained on evenly spaced cross sectional images (slices). Contour interpolation algorithms are implemented in radiation oncology treatment planning software to turn 2D contours into a 3D surface, however the results differ between algorithms, causing discrepancies in analysis. Our goal was to create an accurate and consistent contour interpolation algorithm that can handle issues such as keyhole contours, rapid changes, and branching. This was primarily motivated by radiation therapy research using the open source SlicerRT extension for the 3D Slicer platform. The implemented algorithm triangulates the mesh by minimizing the length of edges spanning the contours with dynamic programming. The first step in the algorithm is removing keyholes from contours. Correspondence is then found between contour layers and branching patterns are determined. The final step is triangulating the contours and sealing the external contours. The algorithm was tested on contours segmented on computed tomography (CT) images. Some cases such as inner contours, rapid changes in contour size, and branching were handled well by the algorithm when encountered individually. There were some special cases in which the simultaneous occurrence of several of these problems in the same location could cause the algorithm to produce suboptimal mesh. An open source contour interpolation algorithm was implemented in SlicerRT for reconstructing surfaces from planar contours. The implemented algorithm was able to generate qualitatively good 3D mesh from the set of 2D contours for most tested structures.

  10. Automatic bootstrapping and tracking of object contours.

    PubMed

    Chiverton, John; Xie, Xianghua; Mirmehdi, Majid

    2012-03-01

    A new fully automatic object tracking and segmentation framework is proposed. The framework consists of a motion-based bootstrapping algorithm concurrent to a shape-based active contour. The shape-based active contour uses finite shape memory that is automatically and continuously built from both the bootstrap process and the active-contour object tracker. A scheme is proposed to ensure that the finite shape memory is continuously updated but forgets unnecessary information. Two new ways of automatically extracting shape information from image data given a region of interest are also proposed. Results demonstrate that the bootstrapping stage provides important motion and shape information to the object tracker. This information is found to be essential for good (fully automatic) initialization of the active contour. Further results also demonstrate convergence properties of the content of the finite shape memory and similar object tracking performance in comparison with an object tracker with unlimited shape memory. Tests with an active contour using a fixed-shape prior also demonstrate superior performance for the proposed bootstrapped finite-shape-memory framework and similar performance when compared with a recently proposed active contour that uses an alternative online learning model. PMID:21908256

  11. A contour-based approach to multisensor image registration.

    PubMed

    Li, H; Manjunath, B S; Mitra, S K

    1995-01-01

    Image registration is concerned with the establishment of correspondence between images of the same scene. One challenging problem in this area is the registration of multispectral/multisensor images. In general, such images have different gray level characteristics, and simple techniques such as those based on area correlations cannot be applied directly. On the other hand, contours representing region boundaries are preserved in most cases. The authors present two contour-based methods which use region boundaries and other strong edges as matching primitives. The first contour matching algorithm is based on the chain-code correlation and other shape similarity criteria such as invariant moments. Closed contours and the salient segments along the open contours are matched separately. This method works well for image pairs in which the contour information is well preserved, such as the optical images from Landsat and Spot satellites. For the registration of the optical images with synthetic aperture radar (SAR) images, the authors propose an elastic contour matching scheme based on the active contour model. Using the contours from the optical image as the initial condition, accurate contour locations in the SAR image are obtained by applying the active contour model. Both contour matching methods are automatic and computationally quite efficient. Experimental results with various kinds of image data have verified the robustness of the algorithms, which have outperformed manual registration in terms of root mean square error at the control points. PMID:18289982

  12. Adaptive pseudo dilation for gestalt edge grouping and contour detection.

    PubMed

    Papari, Giuseppe; Petkov, Nicolai

    2008-10-01

    We consider the problem of detecting object contours in natural images. In many cases, local luminance changes turn out to be stronger in textured areas than on object contours. Therefore, local edge features, which only look at a small neighborhood of each pixel, cannot be reliable indicators of the presence of a contour, and some global analysis is needed. We introduce a new morphological operator, called adaptive pseudo-dilation (APD), which uses context dependent structuring elements in order to identify long curvilinear structure in the edge map. We show that grouping edge pixels as the connected components of the output of APD results in a good agreement with the gestalt law of good continuation. The novelty of this operator is that dilation is limited to the Voronoi cell of each edge pixel. An efficient implementation of APD is presented. The grouping algorithm is then embedded in a multithreshold contour detector. At each threshold level, small groups of edges are removed, and contours are completed by means of a generalized reconstruction from markers. The use of different thresholds makes the algorithm much less sensitive to the values of the input parameters. Both qualitative and quantitative comparison with existing approaches prove the superiority of the proposed contour detector in terms of larger amount of suppressed texture and more effective detection of low-contrast contours. PMID:18784041

  13. How Teamwork Transformed a Neighborhood.

    ERIC Educational Resources Information Center

    Lubetkin, Martie Theleen

    1996-01-01

    Describes a California elementary school serving Hispanic students that successfully involved parents, businesses, and community members in improving school safety, refurbishing the neighborhood, and purging the area of criminal activity. Police and Korean-American merchants have contributed to multicultural celebrations, and PTA participation is…

  14. Doubly rotated contoured quartz resonators.

    PubMed

    Sinha, B K

    2001-09-01

    Doubly rotated contoured quartz resonators are used in the design of temperature-compensated stable clocks and dual-mode sensors for simultaneous measurements of pressure and temperature. The design of these devices is facilitated by models that can predict frequency spectra associated with the three thickness modes and temperature and stress-induced frequency changes as a function of crystalline orientation. The Stevens-Tiersten technique for the analysis of the C-mode of a doubly rotated contoured quartz resonator is extended to include the other two thickness modes. Computational results for harmonic and anharmonic overtones of all three thickness modes of such resonators help in optimizing the radius of curvature of the contour and electrode shape for suppression of unwanted modes and prevention of activity dips. The temperature and stress-induced changes in thickness-mode resonator frequencies are calculated from a perturbation technique for small dynamic fields superposed on a static bias. The static bias refers to either a temperature or stress-induced static deformation of the resonator plate. Phenomenological models are also used for calculating the temperature and stress-induced changes in resonant frequencies as a function of crystalline orientation. Results for the SBTC-cut quartz plate with a spherical convex contour of 260 mm indicate that normal trapping occurs for the third (n = 3) and fifth (n = 5) harmonic of the A-mode, the fundamental (n = 1) and third (n = 3) harmonic of the B-mode, and the fundamental (n = 1) and fifth (n = 5) harmonic of the C-mode. PMID:11570746

  15. Contour detection based on brightness and contour completion

    NASA Astrophysics Data System (ADS)

    Zou, Lamei; Wan, Min; Jin, Liujia; Gao, Yahong; Yang, Weidong

    2015-12-01

    The further research of visual processing mechanism provides a new idea for contour detection. On the primary visual cortex, the non-classical receptive field of the neurons has the orientation selectivity exerts suppression effect on the response of classical receptive field, which influences edge or line perception. Based on the suppression property of non-classical receptive field and contour completion, this paper proposed a contour detection method based on brightness and contour completion. The experiment shows that the proposed method can not only effectively eliminate clutter information, but also connect the broken contour points by taking advantage of contour completion.

  16. Neighborhood Context and Youth Cardiovascular Health Behaviors

    PubMed Central

    Lee, Rebecca E.; Cubbin, Catherine

    2002-01-01

    Objectives. This study sought to determine the relationships between race/ethnicity, socioeconomic status (SES), and cardiovascular health behaviors among youths and whether neighborhood characteristics are associated with such behaviors independently of individual characteristics. Methods. Linear models determined the effects of individual and neighborhood characteristics (SES, social disorganization, racial/ethnic minority concentration, urbanization) on dietary habits, physical activity, and smoking among 8165 youths aged 12 to 21 years. Results. Low SES was associated with poorer dietary habits, less physical activity, and higher odds of smoking. After adjustment for SES, Black race was associated with poorer dietary habits and lower odds of smoking. Hispanic ethnicity was associated with healthier dietary habits, lower levels of physical activity, and lower odds of smoking than non-Hispanic ethnicity. Low neighborhood SES and high neighborhood social disorganization were independently associated with poorer dietary habits, while high neighborhood Hispanic concentration and urbanicity were associated with healthier dietary habits. Neighborhood characteristics were not associated with physical activity or smoking. Conclusions. Changes in neighborhood social structures and policies that reduce social inequalities may enhance cardiovascular health behaviors. (Am J Public Health. 2002;92:428–436) PMID:11867325

  17. The Development of Contour Interpolation: Evidence from Subjective Contours

    ERIC Educational Resources Information Center

    Hadad, Bat-Sheva; Maurer, Daphne; Lewis, Terri L.

    2010-01-01

    Adults are skilled at perceiving subjective contours in regions without any local image information (e.g., [Ginsburg, 1975] and [Kanizsa, 1976]). Here we examined the development of this skill and the effect thereon of the support ratio (i.e., the ratio of the physically specified contours to the total contour length). Children (6-, 9-, and…

  18. Toward a multidimensional understanding of residential neighborhood: a latent profile analysis of Los Angeles neighborhoods and longitudinal adult excess weight

    PubMed Central

    Jones, Malia; Huh, Jimi

    2015-01-01

    People are embedded in a complex socio-spatial context that may affect their weight status through multiple mechanisms, including food & physical activity opportunities and chronic stress exposure. However, research to date has been unable to resolve what features of neighborhoods are causally related to weight status. We used latent profile analysis to identify three “types” of neighborhoods (based on five dimensions of neighborhood social status) in Los Angeles, CA. Our neighborhood types were both substantively interpretable and predictive of excess weight in both cross-sectional and longitudinal models. Our results are promising for a research community attempting to operationalize neighborhoods as multidimensional, complex systems. PMID:24607872

  19. Influences on Neighborhood Walking in Older Adults

    PubMed Central

    Gallagher, Nancy Ambrose; Clarke, Philippa J.; Ronis, David L.; Cherry, Carol Loveland; Nyquist, Linda; Gretebeck, Kimberlee A.

    2014-01-01

    The purpose of this cross-sectional survey study was to examine the influence of self-efficacy, outcome expectations and environment on neighborhood walking in older adults with (n=163, mean age=78.7, SD=7.96 years) and without (n=163, mean age=73.6, SD=7.93 years) mobility limitations (controlling for demographic characteristics). Measures included: Neighborhood Physical Activity Questionnaire, Multidimensional Outcome Expectations for Exercise Scale, Neighborhood Environment Walkability Scale, and self-efficacy scales. Multiple regression revealed that in mobility-limited older adults, demographic characteristics, self-efficacy, and outcome expectations explained 17.4% of variance in neighborhood walking, while environment (neighborhood destinations and design) explained 9.5%. Destinations, self-efficacy, gender, and outcome expectations influenced walking. In those without mobility limitations, demographic characteristics, self-efficacy, and outcome expectations explained 15.6% of the variance, while environment explained 5.7%. Self-efficacy, gender, and design influenced walking. Neighborhood walking interventions for older adults should include self-efficacy strategies tailored to mobility status and neighborhood characteristics. PMID:22998660

  20. The impact of greenery on physical activity and mental health of adolescent and adult residents of deprived neighborhoods: A longitudinal study.

    PubMed

    Gubbels, Jessica S; Kremers, Stef P J; Droomers, Mariël; Hoefnagels, Cees; Stronks, Karien; Hosman, Clemens; de Vries, Sjerp

    2016-07-01

    The aim of the study is to assess the impact of perceived and objective changes in greenery on physical activity and mental health of adolescents and adults living in severely deprived neighborhoods in the Netherlands. Longitudinal data regarding changes in greenery, walking, cycling, and depressive symptoms (CES-D), were gathered for 401 adolescents and 454 adults, using questionnaires and interviews with local district managers. Multivariate linear regression models examined the association between greenery and outcome variables, correcting for demographic and socioeconomic covariates and season. Overall, the results showed small and non-significant associations, with two exceptions. Objective improvements in greenery were associated with smaller decline in adolescents' leisure time cycling, and improvements in perceived greenery were related to a decrease in adults' depressive symptoms. In addition, there were several subgroup effects. In conclusion, changes in greenery did not yield consistent positive results among residents of severely deprived neighborhoods. However, there are some indications regarding positive effects of greenery in certain subgroups. PMID:27322564

  1. The price of access: capitalization of neighborhood contextual factors

    PubMed Central

    2013-01-01

    Background Studies of neighborhood context on health behavior have not considered that the health benefits of context may be ‘capitalized’ into, or included in, higher housing values. This study examines the associations of better neighborhood context with neighborhood housing values. Methods We use the third wave of Add Health (2000-2001) to estimate the association of neighborhood contextual variables and housing values first across then within income types. This is a census block group-level analysis. Results We find that neighborhood context, especially access to fruit and vegetable outlets, is capitalized into, or associated with, higher housing values. Fast food and convenience store access are associated with lower housing values. Capitalization differs by income quartile of the neighborhood. Even those in the poorest neighborhoods value access to fresh fruits and vegetables, and those in the wealthier neighborhoods value activity resources. All neighborhood incomes types place negative value on fast food access and convenience store access. Conclusions Access to health-related contextual attributes is capitalized into higher housing prices. Access to fresh fruits and vegetables is valued in neighborhoods of all income levels. Modeling these associations by neighborhood income levels helps explain the mixed results in the literature on the built environment in terms of linking health outcomes to access. PMID:23927010

  2. Accurate and Fully Automatic Hippocampus Segmentation Using Subject-Specific 3D Optimal Local Maps Into a Hybrid Active Contour Model

    PubMed Central

    Gkontra, Polyxeni; Daras, Petros; Maglaveras, Nicos

    2014-01-01

    Assessing the structural integrity of the hippocampus (HC) is an essential step toward prevention, diagnosis, and follow-up of various brain disorders due to the implication of the structural changes of the HC in those disorders. In this respect, the development of automatic segmentation methods that can accurately, reliably, and reproducibly segment the HC has attracted considerable attention over the past decades. This paper presents an innovative 3-D fully automatic method to be used on top of the multiatlas concept for the HC segmentation. The method is based on a subject-specific set of 3-D optimal local maps (OLMs) that locally control the influence of each energy term of a hybrid active contour model (ACM). The complete set of the OLMs for a set of training images is defined simultaneously via an optimization scheme. At the same time, the optimal ACM parameters are also calculated. Therefore, heuristic parameter fine-tuning is not required. Training OLMs are subsequently combined, by applying an extended multiatlas concept, to produce the OLMs that are anatomically more suitable to the test image. The proposed algorithm was tested on three different and publicly available data sets. Its accuracy was compared with that of state-of-the-art methods demonstrating the efficacy and robustness of the proposed method. PMID:27170866

  3. A Method for Extracting Suspected Parotid Lesions in CT Images using Feature-based Segmentation and Active Contours based on Stationary Wavelet Transform

    NASA Astrophysics Data System (ADS)

    Wu, T. Y.; Lin, S. F.

    2013-10-01

    Automatic suspected lesion extraction is an important application in computer-aided diagnosis (CAD). In this paper, we propose a method to automatically extract the suspected parotid regions for clinical evaluation in head and neck CT images. The suspected lesion tissues in low contrast tissue regions can be localized with feature-based segmentation (FBS) based on local texture features, and can be delineated with accuracy by modified active contour models (ACM). At first, stationary wavelet transform (SWT) is introduced. The derived wavelet coefficients are applied to derive the local features for FBS, and to generate enhanced energy maps for ACM computation. Geometric shape features (GSFs) are proposed to analyze each soft tissue region segmented by FBS; the regions with higher similarity GSFs with the lesions are extracted and the information is also applied as the initial conditions for fine delineation computation. Consequently, the suspected lesions can be automatically localized and accurately delineated for aiding clinical diagnosis. The performance of the proposed method is evaluated by comparing with the results outlined by clinical experts. The experiments on 20 pathological CT data sets show that the true-positive (TP) rate on recognizing parotid lesions is about 94%, and the dimension accuracy of delineation results can also approach over 93%.

  4. Accurate and Fully Automatic Hippocampus Segmentation Using Subject-Specific 3D Optimal Local Maps Into a Hybrid Active Contour Model.

    PubMed

    Zarpalas, Dimitrios; Gkontra, Polyxeni; Daras, Petros; Maglaveras, Nicos

    2014-01-01

    Assessing the structural integrity of the hippocampus (HC) is an essential step toward prevention, diagnosis, and follow-up of various brain disorders due to the implication of the structural changes of the HC in those disorders. In this respect, the development of automatic segmentation methods that can accurately, reliably, and reproducibly segment the HC has attracted considerable attention over the past decades. This paper presents an innovative 3-D fully automatic method to be used on top of the multiatlas concept for the HC segmentation. The method is based on a subject-specific set of 3-D optimal local maps (OLMs) that locally control the influence of each energy term of a hybrid active contour model (ACM). The complete set of the OLMs for a set of training images is defined simultaneously via an optimization scheme. At the same time, the optimal ACM parameters are also calculated. Therefore, heuristic parameter fine-tuning is not required. Training OLMs are subsequently combined, by applying an extended multiatlas concept, to produce the OLMs that are anatomically more suitable to the test image. The proposed algorithm was tested on three different and publicly available data sets. Its accuracy was compared with that of state-of-the-art methods demonstrating the efficacy and robustness of the proposed method. PMID:27170866

  5. Computer-Assisted Segmentation of Videocapsule Images Using Alpha-Divergence-Based Active Contour in the Framework of Intestinal Pathologies Detection

    PubMed Central

    Meziou, L.; Histace, A.; Precioso, F.; Romain, O.; Dray, X.; Granado, B.; Matuszewski, B. J.

    2014-01-01

    Visualization of the entire length of the gastrointestinal tract through natural orifices is a challenge for endoscopists. Videoendoscopy is currently the “gold standard” technique for diagnosis of different pathologies of the intestinal tract. Wireless capsule endoscopy (WCE) has been developed in the 1990s as an alternative to videoendoscopy to allow direct examination of the gastrointestinal tract without any need for sedation. Nevertheless, the systematic postexamination by the specialist of the 50,000 (for the small bowel) to 150,000 images (for the colon) of a complete acquisition using WCE remains time-consuming and challenging due to the poor quality of WCE images. In this paper, a semiautomatic segmentation for analysis of WCE images is proposed. Based on active contour segmentation, the proposed method introduces alpha-divergences, a flexible statistical similarity measure that gives a real flexibility to different types of gastrointestinal pathologies. Results of segmentation using the proposed approach are shown on different types of real-case examinations, from (multi)polyp(s) segmentation, to radiation enteritis delineation. PMID:25587264

  6. Computer-assisted segmentation of videocapsule images using alpha-divergence-based active contour in the framework of intestinal pathologies detection.

    PubMed

    Meziou, L; Histace, A; Precioso, F; Romain, O; Dray, X; Granado, B; Matuszewski, B J

    2014-01-01

    Visualization of the entire length of the gastrointestinal tract through natural orifices is a challenge for endoscopists. Videoendoscopy is currently the "gold standard" technique for diagnosis of different pathologies of the intestinal tract. Wireless capsule endoscopy (WCE) has been developed in the 1990s as an alternative to videoendoscopy to allow direct examination of the gastrointestinal tract without any need for sedation. Nevertheless, the systematic postexamination by the specialist of the 50,000 (for the small bowel) to 150,000 images (for the colon) of a complete acquisition using WCE remains time-consuming and challenging due to the poor quality of WCE images. In this paper, a semiautomatic segmentation for analysis of WCE images is proposed. Based on active contour segmentation, the proposed method introduces alpha-divergences, a flexible statistical similarity measure that gives a real flexibility to different types of gastrointestinal pathologies. Results of segmentation using the proposed approach are shown on different types of real-case examinations, from (multi)polyp(s) segmentation, to radiation enteritis delineation. PMID:25587264

  7. Neighborhood Poverty. Policy Implications in Studying Neighborhoods. Volume II.

    ERIC Educational Resources Information Center

    Brooks-Gunn, Jeanne, Ed.; Duncan, Greg J., Ed.; Aber, J. Lawrence, Ed.

    Volume 2 of the "Neighborhood Poverty" series incorporates empirical data on neighborhood poverty into discussions of policy and program development. The chapters are: (1) "Ecological Perspectives on the Neighborhood Context of Urban Poverty: Past and Present" (Robert J. Sampson and Jeffrey D. Morenoff); (2) "The Influence of Neighborhoods on…

  8. Segmentation of the endocardial wall of the left atrium using local region-based active contours and statistical shape learning

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Gholami, Behnood; MacLeod, Robert S.; Blauer, Joshua; Haddad, Wassim M.; Tannenbaum, Allen R.

    2010-03-01

    Atrial fibrillation, a cardiac arrhythmia characterized by unsynchronized electrical activity in the atrial chambers of the heart, is a rapidly growing problem in modern societies. One treatment, referred to as catheter ablation, targets specific parts of the left atrium for radio frequency ablation using an intracardiac catheter. Magnetic resonance imaging has been used for both pre- and and post-ablation assessment of the atrial wall. Magnetic resonance imaging can aid in selecting the right candidate for the ablation procedure and assessing post-ablation scar formations. Image processing techniques can be used for automatic segmentation of the atrial wall, which facilitates an accurate statistical assessment of the region. As a first step towards the general solution to the computer-assisted segmentation of the left atrial wall, in this paper we use shape learning and shape-based image segmentation to identify the endocardial wall of the left atrium in the delayed-enhancement magnetic resonance images.

  9. Application and histology-driven refinement of active contour models to functional region and nerve delineation: towards a digital brainstem atlas

    NASA Astrophysics Data System (ADS)

    Patel, Nirmal; Sultana, Sharmin; Rashid, Tanweer; Krusienski, Dean; Audette, Michel A.

    2015-03-01

    This paper presents a methodology for the digital formatting of a printed atlas of the brainstem and the delineation of cranial nerves from this digital atlas. It also describes on-going work on the 3D resampling and refinement of the 2D functional regions and nerve contours. In MRI-based anatomical modeling for neurosurgery planning and simulation, the complexity of the functional anatomy entails a digital atlas approach, rather than less descriptive voxel or surface-based approaches. However, there is an insufficiency of descriptive digital atlases, in particular of the brainstem. Our approach proceeds from a series of numbered, contour-based sketches coinciding with slices of the brainstem featuring both closed and open contours. The closed contours coincide with functionally relevant regions, whereby our objective is to fill in each corresponding label, which is analogous to painting numbered regions in a paint-by-numbers kit. Any open contour typically coincides with a cranial nerve. This 2D phase is needed in order to produce densely labeled regions that can be stacked to produce 3D regions, as well as identifying the embedded paths and outer attachment points of cranial nerves. Cranial nerves are modeled using an explicit contour based technique called 1-Simplex. The relevance of cranial nerves modeling of this project is two-fold: i) this atlas will fill a void left by the brain segmentation communities, as no suitable digital atlas of the brainstem exists, and ii) this atlas is necessary to make explicit the attachment points of major nerves (except I and II) having a cranial origin. Keywords: digital atlas, contour models, surface models

  10. [Post bariatric body contouring.

    PubMed

    Winge, Rikke; Henriksen, Trine Foged; Printzlau, Andreas; Hülmich, Lisbet

    2014-03-17

    Post bariatric body contouring in Denmark is currently a field under development. The scope of this article is to give an overview of existing plastic surgery techniques being used to treat patients with massive weight loss, as well as the current indications for patient referral. Furthermore, we describe how to optimise the preoperative evaluation of the patient and give a brief description of potential surgical adverse effects and their prevalence. Further research can provide this field with invaluable data regarding the post-operative effects on patient rehabilitation and quality of life. PMID:25096208

  11. Robot Hand Would Adapt To Contours

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.

    1990-01-01

    Conceptual device uses hydraulic pressure to activate fingers. Projections on opposing fingers of proposed robot hand automatically conform to contours of object on contact. Pistons connected to common reservoir provide gentle, firm grip. Fingers communicate with each other via hydraulic pressure, without elaborate control system. Pistons move in and out, and tips slope to match contour of object. Their action tends to center object on finger. Hand used to grasp objects of various shapes and sizes. Conforming process passive; pressure of object on one or several pad elements forces other pad elements to touch it. Would not use elaborate mechanisms involving motors, cams, and cables.

  12. Detecting neighborhood vacancy level in Detroit city using remote sensing

    NASA Astrophysics Data System (ADS)

    Li, X.; Wang, R.; Yang, A.; Vojnovic, I.

    2015-12-01

    With the decline of manufacturing industries, many Rust Belt cities, which enjoyed prosperity in the past, are now suffering from financial stress, population decrease and urban poverty. As a consequence, urban neighborhoods deteriorate. Houses are abandoned and left to decay. Neighborhood vacancy brings on many problems. Governments and agencies try to survey the vacancy level by going through neighborhoods and record the condition of each structure, or by buying information of active mailing addresses to get approximate neighborhood vacancy rate. But these methods are expensive and time consuming. Remote sensing provides a quick and comparatively cost-efficient way to access spatial information on social and demographical attributes of urban area. In our study, we use remote sensing to detect a major aspect of neighborhood deterioration, the vacancy levels of neighborhoods in Detroit city. We compared different neighborhoods using Landsat 8 images in 2013. We calculated NDVI that indicates the greenness of neighborhoods with the image in July 2013. Then we used thermal infrared information from image in February to detect human activities. In winter, abandoned houses will not consume so much energy and therefore neighborhoods with more abandoned houses will have smaller urban heat island effect. Controlling for the differences in terms of the greenness obtained from summer time image, we used thermal infrared from winter image to determine the temperatures of urban surface. We find that hotter areas are better maintained and have lower house vacancy rates. We also compared the changes over time for neighborhoods using Landsat 7 images from 2003 to 2013. The results show that deteriorated neighborhoods have increased NDVI in summer and get colder in winter due to abandonment of houses. Our results show the potential application of remote sensing as an easily accessed and efficient way to obtain data about social conditions in cities. We used the neighborhood

  13. Magnetic Resonance Imaging-Based Target Volume Delineation in Radiation Therapy Treatment Planning for Brain Tumors Using Localized Region-Based Active Contour

    SciTech Connect

    Aslian, Hossein; Sadeghi, Mahdi; Mahdavi, Seied Rabie; Babapour Mofrad, Farshid; Astarakee, Mahdi; Khaledi, Navid; Fadavi, Pedram

    2013-09-01

    Purpose: To evaluate the clinical application of a robust semiautomatic image segmentation method to determine the brain target volumes in radiation therapy treatment planning. Methods and Materials: A local robust region-based algorithm was used on MRI brain images to study the clinical target volume (CTV) of several patients. First, 3 oncologists delineated CTVs of 10 patients manually, and the process time for each patient was calculated. The averages of the oncologists’ contours were evaluated and considered as reference contours. Then, to determine the CTV through the semiautomatic method, a fourth oncologist who was blind to all manual contours selected 4-8 points around the edema and defined the initial contour. The time to obtain the final contour was calculated again for each patient. Manual and semiautomatic segmentation were compared using 3 different metric criteria: Dice coefficient, Hausdorff distance, and mean absolute distance. A comparison also was performed between volumes obtained from semiautomatic and manual methods. Results: Manual delineation processing time of tumors for each patient was dependent on its size and complexity and had a mean (±SD) of 12.33 ± 2.47 minutes, whereas it was 3.254 ± 1.7507 minutes for the semiautomatic method. Means of Dice coefficient, Hausdorff distance, and mean absolute distance between manual contours were 0.84 ± 0.02, 2.05 ± 0.66 cm, and 0.78 ± 0.15 cm, and they were 0.82 ± 0.03, 1.91 ± 0.65 cm, and 0.7 ± 0.22 cm between manual and semiautomatic contours, respectively. Moreover, the mean volume ratio (=semiautomatic/manual) calculated for all samples was 0.87. Conclusions: Given the deformability of this method, the results showed reasonable accuracy and similarity to the results of manual contouring by the oncologists. This study shows that the localized region-based algorithms can have great ability in determining the CTV and can be appropriate alternatives for manual approaches in brain cancer.

  14. Contour Completion Without Region Segmentation.

    PubMed

    Ming, Yansheng; Li, Hongdong; He, Xuming

    2016-08-01

    Contour completion plays an important role in visual perception, where the goal is to group fragmented low-level edge elements into perceptually coherent and salient contours. Most existing methods for contour completion have focused on pixelwise detection accuracy. In contrast, fewer methods have addressed the global contour closure effect, despite psychological evidences for its importance. This paper proposes a purely contour-based higher order CRF model to achieve contour closure, through local connectedness approximation. This leads to a simplified problem structure, where our higher order inference problem can be transformed into an integer linear program and be solved efficiently. Compared with the methods based on the same bottom-up edge detector, our method achieves a superior contour grouping ability (measured by Rand index), a comparable precision-recall performance, and more visually pleasing results. Our results suggest that contour closure can be effectively achieved in contour domain, in contrast to a popular view that segmentation is essential for this purpose. PMID:27168599

  15. Method for contour extraction for object representation

    DOEpatents

    Skourikhine, Alexei N.; Prasad, Lakshman

    2005-08-30

    Contours are extracted for representing a pixelated object in a background pixel field. An object pixel is located that is the start of a new contour for the object and identifying that pixel as the first pixel of the new contour. A first contour point is then located on the mid-point of a transition edge of the first pixel. A tracing direction from the first contour point is determined for tracing the new contour. Contour points on mid-points of pixel transition edges are sequentially located along the tracing direction until the first contour point is again encountered to complete tracing the new contour. The new contour is then added to a list of extracted contours that represent the object. The contour extraction process associates regions and contours by labeling all the contours belonging to the same object with the same label.

  16. Roads Centre-Axis Extraction in Airborne SAR Images: AN Approach Based on Active Contour Model with the Use of Semi-Automatic Seeding

    NASA Astrophysics Data System (ADS)

    Lotte, R. G.; Sant'Anna, S. J. S.; Almeida, C. M.

    2013-05-01

    Research works dealing with computational methods for roads extraction have considerably increased in the latest two decades. This procedure is usually performed on optical or microwave sensors (radar) imagery. Radar images offer advantages when compared to optical ones, for they allow the acquisition of scenes regardless of atmospheric and illumination conditions, besides the possibility of surveying regions where the terrain is hidden by the vegetation canopy, among others. The cartographic mapping based on these images is often manually accomplished, requiring considerable time and effort from the human interpreter. Maps for detecting new roads or updating the existing roads network are among the most important cartographic products to date. There are currently many studies involving the extraction of roads by means of automatic or semi-automatic approaches. Each of them presents different solutions for different problems, making this task a scientific issue still open. One of the preliminary steps for roads extraction can be the seeding of points belonging to roads, what can be done using different methods with diverse levels of automation. The identified seed points are interpolated to form the initial road network, and are hence used as an input for an extraction method properly speaking. The present work introduces an innovative hybrid method for the extraction of roads centre-axis in a synthetic aperture radar (SAR) airborne image. Initially, candidate points are fully automatically seeded using Self-Organizing Maps (SOM), followed by a pruning process based on specific metrics. The centre-axis are then detected by an open-curve active contour model (snakes). The obtained results were evaluated as to their quality with respect to completeness, correctness and redundancy.

  17. Family and Neighborhood Risks: How They Relate to Involvement in Out-of-School Time Activities. Research-to-Results Fact Sheet. Publication #2008-06

    ERIC Educational Resources Information Center

    Moore, Kristin A.; Kahn, Jordan

    2008-01-01

    Many studies find that children in "high-risk neighborhoods" are less likely to participate in out-of-school time programs and are more likely to have poor outcomes than are their peers from more advantaged neighborhoods. These poorer outcomes may result from the lower levels of resources, social cohesion, and trust present in high-risk…

  18. Precision contour gage

    DOEpatents

    Bieg, Lothar F.

    1990-12-11

    An apparatus for gaging the contour of a machined part includes a rotary slide assembly, a kinematic mount to move the apparatus into and out of position for measuring the part while the part is still on the machining apparatus, a linear probe assembly with a suspension arm and a probe assembly including as probe tip for providing a measure of linear displacement of the tip on the surface of the part, a means for changing relative positions between the part and the probe tip, and a means for recording data points representing linear positions of the probe tip at prescribed rotation intervals in the position changes between the part and the probe tip.

  19. Precision contour gage

    DOEpatents

    Bieg, L.F.

    1990-12-11

    An apparatus for gaging the contour of a machined part includes a rotary slide assembly, a kinematic mount to move the apparatus into and out of position for measuring the part while the part is still on the machining apparatus, a linear probe assembly with a suspension arm and a probe assembly including as probe tip for providing a measure of linear displacement of the tip on the surface of the part, a means for changing relative positions between the part and the probe tip, and a means for recording data points representing linear positions of the probe tip at prescribed rotation intervals in the position changes between the part and the probe tip. 5 figs.

  20. Generation algorithm of craniofacial structure contour in cephalometric images

    NASA Astrophysics Data System (ADS)

    Mondal, Tanmoy; Jain, Ashish; Sardana, H. K.

    2010-02-01

    Anatomical structure tracing on cephalograms is a significant way to obtain cephalometric analysis. Computerized cephalometric analysis involves both manual and automatic approaches. The manual approach is limited in accuracy and repeatability. In this paper we have attempted to develop and test a novel method for automatic localization of craniofacial structure based on the detected edges on the region of interest. According to the grey scale feature at the different region of the cephalometric images, an algorithm for obtaining tissue contour is put forward. Using edge detection with specific threshold an improved bidirectional contour tracing approach is proposed by an interactive selection of the starting edge pixels, the tracking process searches repetitively for an edge pixel at the neighborhood of previously searched edge pixel to segment images, and then craniofacial structures are obtained. The effectiveness of the algorithm is demonstrated by the preliminary experimental results obtained with the proposed method.

  1. Film coatings for contoured surfaces

    NASA Technical Reports Server (NTRS)

    Flanery, H. E.; Frost, R. K.; Olson, A. J.

    1981-01-01

    Thickness of fluorocarbon elastomer films applied in contoured shapes by vacuum forming is difficult to control at sharply curved areas. Process for spraying contoured fluorocarbon elastomer films of uniform strength and thickness has been used instead of vacuum forming to fabricate curtain covering external tank of Space Shuttle. Conventional spray equipment may be used.

  2. Sensory Information and Subjective Contour

    ERIC Educational Resources Information Center

    Brussell, Edward M.; And Others

    1977-01-01

    The possibility that subjective contours are an artifact of brightness contrast was explored. Concludes that subjective contour and brightness contrast are distinct perceptual phenomena but share a dependency on the processing of edge information transmitted through the achromatic channels of the visual system. (Editor/RK)

  3. MAINE CONTOUR LINES 500 FEET

    EPA Science Inventory

    MECON500 contains 500 foot contour intervals for Maine, generated from USGS 1:250,000 DEMs. Arcs are coded by elevation. Due to the nature of the source data, the positional accuracy of these contour lines varies from good to poor. Use of these data at scales of greater then 1:2...

  4. MAINE CONTOUR LINES 60 FEET

    EPA Science Inventory

    MECON60 contains contours at 60 foot intervals for the entire state of Maine as generated from USGS 1:250,000 scale digital elevation models using ARC/INFO software. Arcs are coded by elevation. Due to the nature of the source data, the positional accuracy of these contour line...

  5. A general purpose contouring system

    USGS Publications Warehouse

    Evenden, Gerald Ian

    1975-01-01

    Three Decsystem-10 FORTRAN IV programs provide a general purpose system for contouring two-dimensional data. The system can provide both quick or final, publication quality contour maps on either interactive or offline plotting devices. Complete user documentation, with examples, and program listings are presented.

  6. Contour Integration across Spatial Frequency

    ERIC Educational Resources Information Center

    Persike, Malte; Olzak, Lynn A.; Meinhardt, Gunter

    2009-01-01

    Association field models of contour integration suggest that local band-pass elements are spatially grouped to global contours within limited bands of spatial frequency (Field, Hayes, & Hess, 1993). While results for local orientation and spacing variation render support for AF models, effects of spatial frequency (SF) have rarely been addressed.…

  7. Running to the Store? The Relationship between Neighborhood Environments and the Risk of Obesity

    PubMed Central

    Zick, Cathleen; Smith, Ken R; Fan, Jessie X; Brown, Barbara B; Yamada, Ikuho; Kowaleski-Jones, Lori

    2009-01-01

    We expand the search for modifiable features of neighborhood environments that alter obesity risk in two ways. First, we examine residents’ access to neighborhood retail food options in combination with neighborhood features that facilitate physical activity. Second, we evaluate neighborhood features for both low income and non-low income neighborhoods (bottom quartile of median neighborhood income vs. the top three quartiles). Our analyses use data from the Utah Population Database merged with U.S. Census data and Dun & Bradstreet business data for Salt Lake County, Utah. Linear regressions for BMI and logistic regressions for the likelihood of being obese are estimated using various measures of the individual’s neighborhood food options and walkability features. As expected, walkability indicators of older neighborhoods and neighborhoods where a higher fraction of the population walks to work is related to a lower BMI/obesity risk, although the strength of the effects varies by neighborhood income. Surprisingly, the walkability indicator of neighborhoods with higher intersection density was linked to higher BMI/obesity risk. The expected inverse relationship between the walkability indicator of population density and BMI/obesity risk is found only in low income neighborhoods. We find a strong association between neighborhood retail food options and BMI/obesity risk with the magnitude of the effects again varying by neighborhood income. For individuals living in non-low income neighborhoods, having one or more convenience stores, full-service restaurants, or fast food restaurants is associated with reduced BMI/obesity risk, compared to having no neighborhood food outlets. The presence of at least one healthy grocery option in low income neighborhoods is also associated with a reduction in BMI/obesity risk relative to no food outlets. Finally, multiple food options within a neighborhood reduce BMI/obesity risk, relative to no food options, for individuals

  8. Contour Error Map Algorithm

    NASA Technical Reports Server (NTRS)

    Merceret, Francis; Lane, John; Immer, Christopher; Case, Jonathan; Manobianco, John

    2005-01-01

    The contour error map (CEM) algorithm and the software that implements the algorithm are means of quantifying correlations between sets of time-varying data that are binarized and registered on spatial grids. The present version of the software is intended for use in evaluating numerical weather forecasts against observational sea-breeze data. In cases in which observational data come from off-grid stations, it is necessary to preprocess the observational data to transform them into gridded data. First, the wind direction is gridded and binarized so that D(i,j;n) is the input to CEM based on forecast data and d(i,j;n) is the input to CEM based on gridded observational data. Here, i and j are spatial indices representing 1.25-km intervals along the west-to-east and south-to-north directions, respectively; and n is a time index representing 5-minute intervals. A binary value of D or d = 0 corresponds to an offshore wind, whereas a value of D or d = 1 corresponds to an onshore wind. CEM includes two notable subalgorithms: One identifies and verifies sea-breeze boundaries; the other, which can be invoked optionally, performs an image-erosion function for the purpose of attempting to eliminate river-breeze contributions in the wind fields.

  9. Robust contour tracking in ultrasound tongue image sequences.

    PubMed

    Xu, Kele; Yang, Yin; Stone, Maureen; Jaumard-Hakoun, Aurore; Leboullenger, Clémence; Dreyfus, Gérard; Roussel, Pierre; Denby, Bruce

    2016-01-01

    A new contour-tracking algorithm is presented for ultrasound tongue image sequences, which can follow the motion of tongue contours over long durations with good robustness. To cope with missing segments caused by noise, or by the tongue midsagittal surface being parallel to the direction of ultrasound wave propagation, active contours with a contour-similarity constraint are introduced, which can be used to provide 'prior' shape information. Also, in order to address accumulation of tracking errors over long sequences, we present an automatic re-initialization technique, based on the complex wavelet image similarity index. Experiments on synthetic data and on real 60 frame per second (fps) data from different subjects demonstrate that the proposed method gives good contour tracking for ultrasound image sequences even over durations of minutes, which can be useful in applications such as speech recognition where very long sequences must be analyzed in their entirety. PMID:26786063

  10. Recognizing the authenticity of emotional expressions: F0 contour matters when you need to know

    PubMed Central

    Drolet, Matthis; Schubotz, Ricarda I.; Fischer, Julia

    2014-01-01

    Authenticity of vocal emotion expression affects emotion recognition and brain activity in the so-called Theory of Mind (ToM) network, which is implied in the ability to explain and predict behavior by attributing mental states to other individuals. Exploiting the variability of the fundamental frequency (F0 contour), which varies more (higher contour) in play-acted expressions than authentic ones, we examined whether contour biases explicit categorization toward a particular authenticity or emotion category. Moreover, we tested whether contour modulates blood-oxygen-level dependent (BOLD) response in the ToM network and explored the role of task as a top-down modulator. The effects of contour on BOLD signal were analyzed by contrasting high and low contour stimuli within two previous fMRI studies that implemented emotion and authenticity rating tasks. Participants preferentially categorized higher contour stimuli as play-acted and lower contour stimuli as sad. Higher contour was found to up-regulate activation task-independently in the primary auditory cortex. Stimulus contour and task were found to interact in a network including medial prefrontal cortex, with an increase in BOLD signal for low-contour stimuli during explicit perception of authenticity and an increase for high-contour stimuli during explicit perception of emotion. Contour-induced BOLD effects appear to be purely stimulus-driven in early auditory and intonation perception, while being strongly task-dependent in regions involved in higher cognition. PMID:24701202

  11. Brain networks supporting perceptual grouping and contour selection

    PubMed Central

    Volberg, Gregor; Greenlee, Mark W.

    2014-01-01

    The human visual system groups local elements into global objects seemingly without effort. Using a contour integration task and EEG source level analyses, we tested the hypothesis that perceptual grouping requires a top-down selection, rather than a passive pooling, of neural information that codes local elements in the visual image. The participants were presented visual displays with or without a hidden contour. Two tasks were performed: a central luminance-change detection task and a peripheral contour detection task. Only in the contour-detection task could we find differential brain activity between contour and non-contour conditions, within a distributed brain network including parietal, lateral occipital and primary visual areas. Contour processing was associated with an inflow of information from lateral occipital into primary visual regions, as revealed from the slope of phase differences between source level oscillations within these areas. The findings suggest that contour integration results from a selection of neural information from lower visual areas, and that this selection is driven by the lateral occipital cortex. PMID:24772096

  12. Public transit generates new physical activity: Evidence from individual GPS and accelerometer data before and after light rail construction in a neighborhood of Salt Lake City, Utah, USA.

    PubMed

    Miller, Harvey J; Tribby, Calvin P; Brown, Barbara B; Smith, Ken R; Werner, Carol M; Wolf, Jean; Wilson, Laura; Oliveira, Marcelo G Simas

    2015-11-01

    Poor health outcomes from insufficient physical activity (PA) are a persistent public health issue. Public transit is often promoted for positive influence on PA. Although there is cross-sectional evidence that transit users have higher PA levels, this may be coincidental or shifted from activities such as recreational walking. We use a quasi-experimental design to test if light rail transit (LRT) generated new PA in a neighborhood of Salt Lake City, Utah, USA. Participants (n=536) wore Global Positioning System (GPS) receivers and accelerometers before (2012) and after (2013) LRT construction. We test within-person differences in individuals' PA time based on changes in transit usage pre- versus post-intervention. We map transit-related PA to detect spatial clustering of PA around the new transit stops. We analyze within-person differences in PA time based on daily transit use and estimate the effect of daily transit use on PA time controlling for socio-demographic variables. Results suggest that transit use directly generates new PA that is not shifted from other PA. This supports the public health benefits from new high quality public transit such as LRT. PMID:26340643

  13. Nonprofit Housing and Neighborhood Spillovers

    ERIC Educational Resources Information Center

    Ellen, Ingrid Gould; Voicu, Ioan

    2006-01-01

    Nonprofit organizations play a critical role in U.S. housing policy, a role typically justified by the claim that their housing investments produce significant neighbor-hood spillover benefits. However, little work has actually been done to measure these impacts on neighborhoods. This paper compares the neighborhood spillover effects of…

  14. A Neighborhood Story

    ERIC Educational Resources Information Center

    Gerrish, Michael

    2009-01-01

    Blue collar doesn't have to mean drab and dull. At least, not to Troy, New York, historian Mike Esposito, who is a member of a neighborhood revitalization movement seeking to celebrate the people and events that brought diversity, prosperity, and vitality to this upstate New York community more than 100 years ago. Esposito and others invited…

  15. Wavelet Representation of Contour Sets

    SciTech Connect

    Bertram, M; Laney, D E; Duchaineau, M A; Hansen, C D; Hamann, B; Joy, K I

    2001-07-19

    We present a new wavelet compression and multiresolution modeling approach for sets of contours (level sets). In contrast to previous wavelet schemes, our algorithm creates a parametrization of a scalar field induced by its contoum and compactly stores this parametrization rather than function values sampled on a regular grid. Our representation is based on hierarchical polygon meshes with subdivision connectivity whose vertices are transformed into wavelet coefficients. From this sparse set of coefficients, every set of contours can be efficiently reconstructed at multiple levels of resolution. When applying lossy compression, introducing high quantization errors, our method preserves contour topology, in contrast to compression methods applied to the corresponding field function. We provide numerical results for scalar fields defined on planar domains. Our approach generalizes to volumetric domains, time-varying contours, and level sets of vector fields.

  16. Non-contact contour gage

    DOEpatents

    Bieg, Lothar F.

    1990-12-18

    A fluid probe for measuring the surface contour of a machined part is provided whereby the machined part can remain on the machining apparatus during surface contour measurement. A measuring nozzle in a measuring probe directs a measuring fluid flow onto the surface. The measuring nozzle is on the probe situated midway between two guide nozzles that direct guide fluid flows onto the surface. When the guide fluid flows interact with the surface, they cause the measuring flow and measuring probe to be oriented perpendicular to the surface. The measuring probe includes a pressure chamber whose pressure is monitored. As the measuring fluid flow encounters changes in surface contour, pressure changes occur in the pressure chamber. The surface contour is represented as data corresponding to pressure changes in the pressure chamber as the surface is scanned.

  17. NEIGHBORHOOD NORMS AND SUBSTANCE USE AMONG TEENS

    PubMed Central

    Musick, Kelly; Seltzer, Judith A.; Schwartz, Christine R.

    2008-01-01

    This paper uses new data from the Los Angeles Family and Neighborhood Survey (L.A. FANS) to examine how neighborhood norms shape teenagers’ substance use. Specifically, it takes advantage of clustered data at the neighborhood level to relate adult neighbors’ attitudes and behavior with respect to smoking, drinking, and drugs, which we treat as norms, to teenagers’ own smoking, drinking, and drug use. We use hierarchical linear models to account for parents’ attitudes and behavior and other characteristics of individuals and families. We also investigate how the association between neighborhood norms and teen behavior depends on: (1) the strength of norms, as measured by consensus in neighbors’ attitudes and conformity in their behavior; (2) the willingness and ability of neighbors to enforce norms, for instance, by monitoring teens’ activities; and (3) the degree to which teens are exposed to their neighbors. We find little association between neighborhood norms and teen substance use, regardless of how we condition the relationship. We discuss possible theoretical and methodological explanations for this finding. PMID:18496598

  18. Generalized gradient and contour program

    USGS Publications Warehouse

    Hellman, Marshall Strong

    1972-01-01

    This program computes estimates of gradients, prepares contour maps, and plots various sets of data provided by the user on the CalComp plotters. The gradients represent the maximum rates of change of a real variable Z=f(X,Y) with respect to the twodimensional rectangle on which the function is defined. The contours are lines of equal Z values. The program also plots special line data sets provided by the user.

  19. Moderating effects of age, gender and education on the associations of perceived neighborhood environment attributes with accelerometer-based physical activity: The IPEN adult study.

    PubMed

    Van Dyck, Delfien; Cerin, Ester; De Bourdeaudhuij, Ilse; Salvo, Deborah; Christiansen, Lars B; Macfarlane, Duncan; Owen, Neville; Mitas, Josef; Troelsen, Jens; Aguinaga-Ontoso, Ines; Davey, Rachel; Reis, Rodrigo; Sarmiento, Olga L; Schofield, Grant; Conway, Terry L; Sallis, James F

    2015-11-01

    The study's purpose was to examine age, gender, and education as potential moderators of the associations of perceived neighborhood environment variables with accelerometer-based moderate-to-vigorous physical activity (MVPA). Data were from 7273 adults from 16 sites (11 countries) that were part of a coordinated multi-country cross-sectional study. Age moderated the associations of perceived crime safety, and perceiving no major physical barriers to walking, with MVPA: positive associations were only found in older adults. Perceived land use mix-access was linearly (positive) associated with MVPA in men, and curvilinearly in women. Perceived crime safety was related to MVPA only in women. No moderating relationships were found for education. Overall the associations of adults' perceptions of environmental attributes with MVPA were largely independent of the socio-demographic factors examined. These findings are encouraging, suggesting that efforts to optimize the perceived built and social environment may act in a socially-equitable manner to facilitate MVPA. PMID:26454247

  20. Basic features of low-temperature plasma formation in the course of composite coating synthesis at the active faces of complex contoured hard tools

    NASA Astrophysics Data System (ADS)

    Brzhozovsky, B. M.; Zimnyakov, D. A.; Zinina, E. P.; Martynov, V. V.; Pleshakova, E. S.; Yuvchenko, S. A.

    2016-04-01

    Basic features of combined-discharge low-temperature plasma formation around the surfaces of complex-contoured metal units are considered. It is shown that it makes the possibilities for synthesis of hardened high-durable coatings of hard tools appropriate for material processing in extreme load-temperature conditions. Experimental study of the coating formation was carried out in combination with the analysis of emission spectra of a low-temperature plasma cloud. Some practical examples of the coating applications are presented.

  1. Healthy Neighborhoods: Walkability and Air Pollution

    PubMed Central

    Marshall, Julian D.; Brauer, Michael; Frank, Lawrence D.

    2009-01-01

    Background The built environment may influence health in part through the promotion of physical activity and exposure to pollution. To date, no studies have explored interactions between neighborhood walkability and air pollution exposure. Methods We estimated concentrations of nitric oxide (NO), a marker for direct vehicle emissions), and ozone (O3) and a neighborhood walkability score, for 49,702 (89% of total) postal codes in Vancouver, British Columbia, Canada. NO concentrations were estimated from a land-use regression model, O3 was estimated from ambient monitoring data; walkability was calculated based on geographic attributes such as land-use mix, street connectivity, and residential density. Results All three attributes exhibit an urban–rural gradient, with high walkability and NO concentrations, and low O3 concentrations, near the city center. Lower-income areas tend to have higher NO concentrations and walkability and lower O3 concentrations. Higher-income areas tend to have lower pollution (NO and O3). “Sweet-spot” neighborhoods (low pollution, high walkability) are generally located near but not at the city center and are almost exclusively higher income. Policy implications Increased concentration of activities in urban settings yields both health costs and benefits. Our research identifies neighborhoods that do especially well (and especially poorly) for walkability and air pollution exposure. Work is needed to ensure that the poor do not bear an undue burden of urban air pollution and that neighborhoods designed for walking, bicycling, or mass transit do not adversely affect resident’s exposure to air pollution. Analyses presented here could be replicated in other cities and tracked over time to better understand interactions among neighborhood walkability, air pollution exposure, and income level. PMID:20049128

  2. Context sensitive road traffic noise impact mapping-Taking the neighborhood soundscape into account

    NASA Astrophysics Data System (ADS)

    Klboe, Ronny; Engelien, Erik; Steinnes, Margrete

    2001-05-01

    Road traffic noise exposure contour maps are difficult to interpret by nonexperts who are familiar with neither the road traffic noise exposure measures nor their associated impacts. An alternative is to map impacts such as annoyance. However, in urban areas the noise impacts are multi-factorially determined and context sensitive. In particular people become more annoyed by a given noise level at the most exposed facade of their dwelling when their neighborhood soundscape is even noisier. A two-tiered approach makes use of contextual soundscape information in determining noise impacts and builds contiguous neighborhood sonoscapes delimiting neighborhood areas with similar noise impacts. Neighborhood sonoscape maps facilitate a more precise targeting of local noise abatement measures, and can illustrate the impacts of noise abatement measures. With appropriate classification and class labels neighborhood sonoscapes provide an environmental labeling of the expected perceived sound quality of the neighborhood for consumers, the public and planners. Neighborhood sonoscape maps may be utilized for national stratification and subsequent two-stage cluster sampling of the population. The advantage of this approach is that focused traffic counts, extended sound modeling and monitoring of noise abatement procedures, population composition, etc. can be undertaken for a limited representative set of neighborhood sonoscapes.

  3. Neighborhood comparison operator

    NASA Technical Reports Server (NTRS)

    Gennery, D. B. (Inventor)

    1985-01-01

    Digital values in a moving window are compared by an operator having nine comparators connected to line buffers for receiving a succession of central pixels together with eight neighborhood pixels. A single bit of program control determines whether the neighborhood pixels are to be compared with the central pixel or a threshold value. The central pixel is always compared with the threshold. The omparator output plus 2 bits indicating odd-even pixel/line information about the central pixel addresses a lookup table to provide 14 bits of information, including 2 bits which control a selector to pass either the central pixel value, the other 12 bits of table information, or the bit-wise logical OR of all nine pixels through circuit that implements a very wide OR gate.

  4. Walks on SPR neighborhoods.

    PubMed

    Caceres, Alan Joseph J; Castillo, Juan; Lee, Jinnie; St John, Katherine

    2013-01-01

    A nearest-neighbor-interchange (NNI)-walk is a sequence of unrooted phylogenetic trees, T1, T2, . . . , T(k) where each consecutive pair of trees differs by a single NNI move. We give tight bounds on the length of the shortest NNI-walks that visit all trees in a subtree-prune-and-regraft (SPR) neighborhood of a given tree. For any unrooted, binary tree, T, on n leaves, the shortest walk takes Θ(n²) additional steps more than the number of trees in the SPR neighborhood. This answers Bryant’s Second Combinatorial Challenge from the Phylogenetics Challenges List, the Isaac Newton Institute, 2011, and the Penny Ante Problem List, 2009. PMID:23702562

  5. Entropy reduction via simplified image contourization

    NASA Technical Reports Server (NTRS)

    Turner, Martin J.

    1993-01-01

    The process of contourization is presented which converts a raster image into a set of plateaux or contours. These contours can be grouped into a hierarchical structure, defining total spatial inclusion, called a contour tree. A contour coder has been developed which fully describes these contours in a compact and efficient manner and is the basis for an image compression method. Simplification of the contour tree has been undertaken by merging contour tree nodes thus lowering the contour tree's entropy. This can be exploited by the contour coder to increase the image compression ratio. By applying general and simple rules derived from physiological experiments on the human vision system, lossy image compression can be achieved which minimizes noticeable artifacts in the simplified image.

  6. ADOLESCENTS’ EXPOSURE TO COMMUNITY VIOLENCE: ARE NEIGHBORHOOD YOUTH ORGANIZATIONS PROTECTIVE?

    PubMed Central

    Gardner, Margo; Brooks-Gunn, Jeanne

    2011-01-01

    Using data from the Project on Human Development in Chicago Neighborhoods (PHDCN), we identified a significant inverse association between the variety of youth organizations available at the neighborhood level and adolescents’ exposure to community violence. We examined two non-competing explanations for this finding. First, at the individual level, we tested the hypothesis that access to a greater variety of neighborhood youth organizations predicts adolescents’ participation in organized community-based activities, which, in turn, protects against community violence exposure. Second, at the neighborhood level, we tested the hypothesis that lower violent crime rates explain the inverse relation between neighborhood youth organization variety and community violence exposure. Our findings supported the latter of these two mechanisms. PMID:21666761

  7. Neighborhood Effects in Temporal Perspective

    PubMed Central

    Wodtke, Geoffrey T.; Harding, David J.; Elwert, Felix

    2012-01-01

    Theory suggests that neighborhood effects depend not only on where individuals live today, but also on where they lived in the past. Previous research, however, usually measured neighborhood context only once and did not account for length of residence, thereby understating the detrimental effects of long-term neighborhood disadvantage. This study investigates the effects of duration of exposure to disadvantaged neighborhoods on high school graduation. It follows 4,154 children in the PSID, measuring neighborhood context once per year from age 1 to 17. The analysis overcomes the problem of dynamic neighborhood selection by adapting novel methods of causal inference for time-varying treatments. In contrast to previous analyses, these methods do not “control away” the effect of neighborhood context operating indirectly through time-varying characteristics of the family, and thus they capture the full impact of a lifetime of neighborhood disadvantage. We find that sustained exposure to disadvantaged neighborhoods has a severe impact on high school graduation that is considerably larger than effects reported in prior research. Growing up in the most (compared to the least) disadvantaged quintile of neighborhoods is estimated to reduce the probability of graduation from 96% to 76% for black children, and from 95% to 87% for nonblack children. PMID:22879678

  8. Home Versus Nonhome Neighborhood

    PubMed Central

    Hurvitz, Philip M.; Moudon, Anne Vernez

    2012-01-01

    Introduction Built environment and health research have focused on characteristics of home neighborhoods, whereas overall environmental exposures occur over larger spatial ranges. Purpose Differences in built environment characteristics were analyzed for home and nonhome locations using GPS data. Methods GPS data collected in 2007–2008 were analyzed for 41 subjects in the Seattle area in 2010. Environmental characteristics for 3.8 million locations were measured using novel GIS data sets called SmartMaps, representing spatially continuous values of local built environment variables in the domains of neighborhood composition, utilitarian destinations, transportation infrastructure, and traffic conditions. Using bootstrap sampling, CIs were estimated for differences in built environment values for home (<833 m of home address) and nonhome (>1666 m) GPS locations. Results Home and nonhome built environment values were significantly different for over 90% of variables across subjects (p<0.001). Only 51% of subjects had higher counts of supermarkets near than away from home. Different measures of neighborhood parks yielded varying results. Conclusions SmartMaps helped measure local built environment characteristics for a large set of GPS locations. Most subjects had significantly different home and nonhome built environment exposures. Considering the full range of individuals’ environmental exposures may improve understanding of effects of the built environment on behavior and health outcomes. PMID:22424255

  9. Moving toward implementation: the potential for accountable care organizations and private-public partnerships to advance active neighborhood design.

    PubMed

    Zusman, Edie E; Carr, Sara Jensen; Robinson, Judy; Kasirye, Olivia; Zell, Bonnie; Miller, William Jahmal; Duarte, Teri; Engel, Adrian B; Hernandez, Monica; Horton, Mark B; Williams, Frank

    2014-12-01

    The 2010 Affordable Care Act's (ACA) aims of lowering costs and improving quality of care will renew focus on preventive health strategies. This coincides with a trend in medicine to reconsider population health approaches as part of the standard curriculum. This intersection of new policy and educational climates presents a unique opportunity to reconsider traditional healthcare structures. This paper introduces and advances an alignment that few have considered. We propose that accountable care organizations (ACOs), which are expected to proliferate under the ACA, present the best opportunity to establish partnerships between healthcare, public health, and community-based organizations to achieve the legislation's goals. One example is encouraging daily physical activity via built environment interventions and programs, which is recommended by numerous groups. We highlight how nonprofit organizations in Sacramento, California have been able to leverage influence, capital, and policy to encourage design for active living, and how their work is coordinating with public health and healthcare initiatives. In conclusion, we critically examine potential barriers to the success of partnerships between ACOs and community organizations and encourage further exploration and evaluation. PMID:25117525

  10. Neighborhood Design for Walking and Biking

    PubMed Central

    Brown, Barbara B.; Smith, Ken R.; Hanson, Heidi; Fan, Jessie X.; Kowaleski-Jones, Lori; Zick, Cathleen D.

    2013-01-01

    Background Neighborhood designs often relate to physical activity and to BMI. Purpose Does neighborhood walkability/bikeability relate to BMI and obesity risk and does moderate-to-vigorous physical activity (MVPA) account for some of the relationship? Methods Census 2000 provided walkability/bikeability measures—block group proportions of workers who walk or bike to work, housing age, and population density—and National Health and Nutrition Examination Study (NHANES 2003–2006) provided MVPA accelerometer measures. Regression analyses (2011–2012) adjusted for geographic clustering and multiple control variables. Results Greater density and older housing were associated with lower male BMI in bivariate analyses, but there were no density and housing age effects in multivariate models. For women, greater proportions of neighborhood workers who walk to work (M=0.02) and more MVPA was associated with lower BMI and lower obesity risk. For men, greater proportions of workers who bike to work (M=0.004) and more MVPA was associated with lower BMI and obesity risk. For both effects, MVPA partially mediated the relationships between walkability/bikeability and BMI. If such associations are causal, doubling walk and bike-to-work proportions (to 0.04 and 0.008) would have –0.3 and –0.33 effects on the average BMIs of adult women and men living in the neighborhood. This equates to 1.5 lbs for a 64” woman and 2.3 lbs for a 69” man. Conclusions Although walking/biking to work is rare in the U.S., greater proportions of such workers in neighborhoods relate to lower weight and higher MVPA. Bikeability merits greater attention as a modifiable activity-friendliness factor, particularly for men. PMID:23415119

  11. Walkable new urban LEED_Neighborhood-Development (LEED-ND) community design and children's physical activity: selection, environmental, or catalyst effects?

    PubMed Central

    2011-01-01

    Background Interest is growing in physical activity-friendly community designs, but few tests exist of communities explicitly designed to be walkable. We test whether students living in a new urbanist community that is also a pilot LEED_ND (Leadership in Energy and Environmental Design-Neighborhood Development) community have greater accelerometer-measured moderate-to-vigorous physical activity (MVPA) across particular time periods compared to students from other communities. We test various time/place periods to see if the data best conform to one of three explanations for MVPA. Environmental effects suggest that MVPA occurs when individuals are exposed to activity-friendly settings; selection effects suggest that walkable community residents prefer MVPA, which leads to both their choice of a walkable community and their high levels of MVPA; catalyst effects occur when walking to school creates more MVPA, beyond the school commute, on schooldays but not weekends. Methods Fifth graders (n = 187) were sampled from two schools representing three communities: (1) a walkable community, Daybreak, designed with new urbanist and LEED-ND pilot design standards; (2) a mixed community (where students lived in a less walkable community but attended the walkable school so that part of the route to school was walkable), and (3) a less walkable community. Selection threats were addressed through controlling for parental preferences for their child to walk to school as well as comparing in-school MVPA for the walkable and mixed groups. Results Minutes of MVPA were tested with 3 × 2 (Community by Gender) analyses of covariance (ANCOVAs). Community walkability related to more MVPA during the half hour before and after school and, among boys only, more MVPA after school. Boys were more active than girls, except during the half hour after school. Students from the mixed and walkable communities--who attended the same school--had similar in-school MVPA levels, and community groups

  12. Topological Cacti: Visualizing Contour-based Statistics

    SciTech Connect

    Weber, Gunther H.; Bremer, Peer-Timo; Pascucci, Valerio

    2011-05-26

    Contours, the connected components of level sets, play an important role in understanding the global structure of a scalar field. In particular their nestingbehavior and topology-often represented in form of a contour tree-have been used extensively for visualization and analysis. However, traditional contour trees onlyencode structural properties like number of contours or the nesting of contours, but little quantitative information such as volume or other statistics. Here we use thesegmentation implied by a contour tree to compute a large number of per-contour (interval) based statistics of both the function defining the contour tree as well asother co-located functions. We introduce a new visual metaphor for contour trees, called topological cacti, that extends the traditional toporrery display of acontour tree to display additional quantitative information as width of the cactus trunk and length of its spikes. We apply the new technique to scalar fields ofvarying dimension and different measures to demonstrate the effectiveness of the approach.

  13. MULTISCALE DISCRETIZATION OF SHAPE CONTOURS

    SciTech Connect

    Prasad, L.; Rao, R.

    2000-09-01

    We present an efficient multi-scale scheme to adaptively approximate the continuous (or densely sampled) contour of a planar shape at varying resolutions. The notion of shape is intimately related to the notion of contour, and the efficient representation of the contour of a shape is vital to a computational understanding of the shape. Any polygonal approximation of a planar smooth curve is equivalent to a piecewise constant approximation of the parameterized X and Y coordinate functions of a discrete point set obtained by densely sampling the curve. Using the Haar wavelet transform for the piecewise approximation yields a hierarchical scheme in which the size of the approximating point set is traded off against the morphological accuracy of the approximation. Our algorithm compresses the representation of the initial shape contour to a sparse sequence of points in the plane defining the vertices of the shape's polygonal approximation. Furthermore, it is possible to control the overall resolution of the approximation by a single, scale-independent parameter.

  14. Gage for 3-d contours

    NASA Technical Reports Server (NTRS)

    Haynie, C. C.

    1980-01-01

    Simple gage, used with template, can help inspectors determine whether three-dimensional curved surface has correct contour. Gage was developed as aid in explosive forming of Space Shuttle emergency-escape hatch. For even greater accuracy, wedge can be made of metal and calibrated by indexing machine.

  15. Algorithm for Constructing Contour Plots

    NASA Technical Reports Server (NTRS)

    Johnson, W.; Silva, F.

    1984-01-01

    General computer algorithm developed for construction of contour plots. algorithm accepts as input data values at set of points irregularly distributed over plane. Algorithm based on interpolation scheme: points in plane connected by straight-line segments to form set of triangles. Program written in FORTRAN IV.

  16. Why the Neighborhood Social Environment Is Critical in Obesity Prevention.

    PubMed

    Suglia, Shakira F; Shelton, Rachel C; Hsiao, Amber; Wang, Y Claire; Rundle, Andrew; Link, Bruce G

    2016-02-01

    The continuing obesity epidemic in the USA calls for the examination of antecedents to the well-known risk factors of physical activity and diet. The neighborhood built environment has been extensively studied in relation to obesity noting an increased risk of development and prevalence of obesity in relation to numerous built environment characteristics (lack of green spaces, higher number of fast food restaurants, low walkability indices). The neighborhood social environment, however, has been less extensively studied but is perhaps an equally important component of the neighborhood environment. The neighborhood social environment, particularly constructs of social capital, collective efficacy, and crime, is associated with obesity among both adults and children. Several studies have identified physical activity as a potential pathway of the neighborhood social environment and obesity association. Further work on social networks and norms and residential segregation, as well as the examination of dietary behaviors and mental health as potential mediating pathways, is necessary. Given the existing evidence, intervening on the neighborhood social environment may prove to be an effective target for the prevention on obesity. Intervention studies that promote healthy behaviors and prevent obesity while addressing aspects of the neighborhood social environment are necessary to better identify targets for obesity prevention. PMID:26780582

  17. Measuring and Plotting Surface-Contour Deviations

    NASA Technical Reports Server (NTRS)

    Aragon, Lino A.; Shuck, Thomas; Crockett, Leroy K.

    1987-01-01

    Hand-held device measures deviation of contour of surface from desired contour and provides output to x-y plotter. Carriage on device rolled along track representing desired contour, while spring-loaded stylus on device deflects perpendicularly to track to follow surface. Operator moves carriage of contour-measuring device on beamlike track. Stylus on carriage traces contour of surface above it. Carriage of measuring device holds transducer measuring cross-track displacement of surface from desired contour, and multiple-turn potentiometer measuring position along track.

  18. Hazardous Waste Site Remediation, Neighborhood Change, and Neighborhood Quality.

    PubMed Central

    Greenberg, M; Schneider, D

    1994-01-01

    We tested the hypothesis that neighborhoods with hazardous waste sites may no longer be undesirable places to live if they have been at least partly remediated. We collected 377 questionnaires (42% response rate) administered from within one-half mile of the number 1, 4, and 12 hazardous waste sites on the National Priority List (Superfund). These neighborhoods were rated higher quality than neighborhoods with unremediated hazardous waste sites and about the same as neighborhoods in northern New Jersey and the United States as a whole. Newer residents considered these formerly tainted areas to be opportunities to upgrade their housing and living conditions. Long-term residents retained the negative image of the blemished neighborhood. Images p542-a PMID:9679112

  19. Attractor Dynamics and Semantic Neighborhood Density: Processing Is Slowed by Near Neighbors and Speeded by Distant Neighbors

    PubMed Central

    Mirman, Daniel; Magnuson, James S.

    2008-01-01

    The authors investigated semantic neighborhood density effects on visual word processing to examine the dynamics of activation and competition among semantic representations. Experiment 1 validated feature-based semantic representations as a basis for computing semantic neighborhood density and suggested that near and distant neighbors have opposite effects on word processing. Experiment 2 confirmed these results: Word processing was slower for dense near neighborhoods and faster for dense distant neighborhoods. Analysis of a computational model showed that attractor dynamics can produce this pattern of neighborhood effects. The authors argue for reconsideration of traditional models of neighborhood effects in terms of attractor dynamics, which allow both inhibitory and facilitative effects to emerge. PMID:18194055

  20. The Aging Neighborhood: Phonological Density in Naming

    PubMed Central

    Kurczek, Jake C.

    2013-01-01

    Aging affects the ability to retrieve words for production, despite maintainence of lexical knowledge. In this study, we investigate the influence of lexical variables on picture naming accuracy and latency in adults ranging in age from 22 to 86 years. In particular, we explored the influence of phonological neighborhood density, which has been shown to exert competitive effects on word recognition, but to facilitate word production, a finding with implications for models of the lexicon. Naming responses were slower and less accurate for older participants, as expected. Target frequency also played a strong role, with facilitative frequency effects becoming stronger with age. Neighborhood density interacted with age, such that naming was slower for high-density than low-density items, but only for older subjects. Explaining this finding within an interactive activation model suggests that, as we age, the ability of activated neighbors to facilitate target production diminishes, while their activation puts them in competition with the target. PMID:24563568

  1. Neighborhood inverse consistency preprocessing

    SciTech Connect

    Freuder, E.C.; Elfe, C.D.

    1996-12-31

    Constraint satisfaction consistency preprocessing methods are used to reduce search effort. Time and especially space costs limit the amount of preprocessing that will be cost effective. A new form of consistency preprocessing, neighborhood inverse consistency, can achieve more problem pruning than the usual arc consistency preprocessing in a cost effective manner. There are two basic ideas: (1) Common forms of consistency enforcement basically operate by identifying and remembering solutions to subproblems for which a consistent value cannot be found for some additional problem variable. The space required for this memory can quickly become prohibitive. Inverse consistency basically operates by removing values for variables that are not consistent with any solution to some subproblem involving additional variables. The space requirement is at worst linear. (2) Typically consistency preprocessing achieves some level of consistency uniformly throughout the problem. A subproblem solution will be tested against each additional variable that constrains any subproblem variable. Neighborhood consistency focuses attention on the subproblem formed by the variables that are all constrained by the value in question. By targeting highly relevant subproblems we hope to {open_quotes}skim the cream{close_quotes}, obtaining a high payoff for a limited cost.

  2. Neighborhood Poverty and Adolescent Development

    ERIC Educational Resources Information Center

    McBride Murry, Velma; Berkel, Cady; Gaylord-Harden, Noni K.; Copeland-Linder, Nikeea; Nation, Maury

    2011-01-01

    This article provides a comprehensive review of studies conducted over the past decade on the effects of neighborhood and poverty on adolescent normative and nonnormative development. Our review includes a summary of studies examining the associations between neighborhood poverty and adolescent identity development followed by a review of studies…

  3. Building Strengths in the Neighborhood

    ERIC Educational Resources Information Center

    Quigley, Richard

    2005-01-01

    This article features Woodland Hills's Neighborhood Youth Services. The Neighborhood Youth Services (NYS) program is a community-based program created by Woodland Hills, a residential program for troubled adolescents in Duluth, Minnesota. Principles for building respectful adult and peer relationships developed in the treatment environment were…

  4. Housing, Neighborhoods, and Children's Health

    ERIC Educational Resources Information Center

    Ellen, Ingrid Gould; Glied, Sherry

    2015-01-01

    In theory, improving low-income families' housing and neighborhoods could also improve their children's health, through any number of mechanisms. For example, less exposure to environmental toxins could prevent diseases such as asthma; a safer, less violent neighborhood could improve health by reducing the chances of injury and death, and by…

  5. Incorporating domain knowledge for tubule detection in breast histopathology using O'Callaghan neighborhoods

    NASA Astrophysics Data System (ADS)

    Basavanhally, Ajay; Yu, Elaine; Xu, Jun; Ganesan, Shridar; Feldman, Michael; Tomaszewski, John; Madabhushi, Anant

    2011-03-01

    . The potential lumen areas are segmented using a Hierarchical Normalized Cut (HNCut) initialized Color Gradient based Active Contour model (CGAC). The HNCut algorithm detects lumen-like areas within the image via pixel clustering across multiple image resolutions. The pixel clustering provides initial contours for the CGAC. From the initial contours, the CGAC evolves to segment the boundaries of the potential lumen areas. A set of 22 graph-based image features characterizing the spatial linking between the tubular attributes is extracted from the O'Callaghan neighborhood in order to distinguish true from false lumens. Evaluation on 1226 potential lumen areas from 14 patient studies produces an area under the receiver operating characteristic curve (AUC) of 0.91 along with the ability to classify true lumen with 86% accuracy. In comparison to manual grading of tubular density over 105 images, our method is able to distinguish histopathology images with low and high tubular density at 89% accuracy (AUC = 0.94).

  6. Application Of Moire Contour Fringes To Study Nycticebus Coucany

    NASA Astrophysics Data System (ADS)

    Ren-xiang, Zhang; Ming, Lu; Zu-yun, Lan; Wen-ji, Qu

    1984-12-01

    In this paper we have studied the moire contour fringes of the skull and femur knee joint of Nycticebus coucany and obtained the following results: 1. The skull's value K is very useful for comparative study with the different kinds of Primate. 2. The moire contour fringes of the tibia facies of knee joint is convex on one side while the other side is concave. 3. At the same condition the grade of the first moire contour fringe of connection on the femur knee joint between the two condyles and its angle β are smaller than Hylobates concolor leucongeuys. This study is significant, because: 1. The evolution of skull may be related with the increased value K. 2. The moire contour fringes of the Nycticebus coucany's tibia and femur knee joint have lower range of activity. 3. From the moire contour fringes of knee, the Nycticebus coucany and. Hylobates concolor leucongeuys are of one kind. But the moire contour Nycticebus of tibia is different form.

  7. Adjusting the Contour of Reflector Panels

    NASA Technical Reports Server (NTRS)

    Palmer, W. B.; Giebler, M. M.

    1984-01-01

    Postfabrication adjustment of contour of panels for reflector, such as parabolic reflector for radio antennas, possible with simple mechanism consisting of threaded stud, two nuts, and flexure. Contours adjusted manually.

  8. Contoured Surface Eddy Current Inspection System

    DOEpatents

    Batzinger, Thomas James; Fulton, James Paul; Rose, Curtis Wayne; Perocchi, Lee Cranford

    2003-04-08

    Eddy current inspection of a contoured surface of a workpiece is performed by forming a backing piece of flexible, resiliently yieldable material with a contoured exterior surface conforming in shape to the workpiece contoured surface. The backing piece is preferably cast in place so as to conform to the workpiece contoured surface. A flexible eddy current array probe is attached to the contoured exterior surface of the backing piece such that the probe faces the contoured surface of the workpiece to be inspected when the backing piece is disposed adjacent to the workpiece. The backing piece is then expanded volumetrically by inserting at least one shim into a slot in the backing piece to provide sufficient contact pressure between the probe and the workpiece contoured surface to enable the inspection of the workpiece contoured surface to be performed.

  9. A new look at neighborhoods near National Priorities List sites.

    PubMed

    Heitgerd, Janet L; Lee, Virginia C

    2003-09-01

    A geodemographic database can assess characteristics of communities by providing (1) annual demographic estimates for these small areas, and (2) statistically based models that integrated consumer behavior and lifestyle data. When applied to neighborhoods proximate to National Priorities List (NPL) sites, information from a geodemographic database can inform environmental health risk assessments and aid in targeting health education activities. This study utilized such a database with 1999 census block group population estimates and neighborhood descriptors in the USA. We examined patterns of neighborhood type based on NPL site classification by activity and waste type (e.g., manufacturing, mining). Overall, block groups described as "Military Quarters" are at highest risk of being located near an NPL site. Other, distinct, neighborhood differences are described. PMID:12878110

  10. HOPE VI Neighborhoods and Neighborhood Schools: Understanding How Revitalized Neighborhoods Influence School Environments

    ERIC Educational Resources Information Center

    Smrekar, Claire E.; Bentley, Lydia

    2011-01-01

    This article poses the central question, How do neighborhoods (specifically, different public housing designs) shape parents' social interactions and social networks? To answer this question, we interviewed families residing in a HOPE VI neighborhood and an adjacent Section 8 apartment complex, all of whom had at least one child attending the…

  11. The Stanford Healthy Neighborhood Discovery Tool

    PubMed Central

    Buman, Matthew P.; Winter, Sandra J.; Sheats, Jylana L.; Hekler, Eric B.; Otten, Jennifer J.; Grieco, Lauren A.; King, Abby C.

    2013-01-01

    Background The built environment can influence physical activity, particularly among older populations with impaired mobility. Existing tools to assess environmental features associated with walkability are often cumbersome, require extensive training, and are not readily available for use by community residents. Purpose This project aimed to develop and evaluate the utility of a computerized, tablet-based participatory tool designed to engage older residents in identifying neighborhood elements that affect active living opportunities. Methods Following formative testing, the tool was used by older adults (aged ≥65 years, in 2011) to record common walking routes (tracked using built-in GPS) and geocoded audio narratives and photographs of the local neighborhood environment. Residents (N=27; 73% women; 77% with some college education; 42% used assistive devices) from three low-income communal senior housing sites used the tool while navigating their usual walking route in their neighborhood. Data were analyzed in 2012. Results Elements (from 464 audio narratives and photographs) identified as affecting active living were commensurate with the existing literature (e.g., sidewalk features, aesthetics, parks/playgrounds, crosswalks). However, within each housing site, the profile of environmental elements identified was distinct, reflecting the importance of granular-level information collected by the tool. Additionally, consensus among residents was reached regarding which elements affected active living opportunities. Conclusions This tool serves to complement other assessments and assist decision makers in consensus-building processes for environmental change. PMID:23498112

  12. The Poggendorff illusion driven by real and illusory contour: Behavioral and neural mechanisms.

    PubMed

    Shen, Lu; Zhang, Ming; Chen, Qi

    2016-05-01

    The Poggendorff illusion refers to the phenomenon that the human brain misperceives a diagonal line as being apparently misaligned once the diagonal line is interrupted by two parallel edges, and the size of illusion is negatively correlated with the angle of interception of the oblique, i.e. the sharper the oblique angle, the larger the illusion. This optical illusion can be produced by both real and illusory contour. In this fMRI study, by parametrically varying the oblique angle, we investigated the shared and specific neural mechanisms underlying the Poggendorff illusion induced by real and illusory contour. At the behavioral level, not only the real but also the illusory contours were capable of inducing significant Poggendorff illusion. The size of illusion induced by the real contour, however, was larger than that induced by the illusory contour. At the neural level, real and illusory contours commonly activated more dorsal visual areas, and the real contours specifically activated more ventral visual areas. More importantly, examinations on the parametric modulation effects of the size of illusion revealed the specific neural mechanisms underlying the Poggendorff illusion induced by the real and the illusory contours, respectively. Left precentral gyrus and right middle occipital cortex were specifically involved in the Poggendorff illusion induced by the real contour. On the other hand, bilateral intraparietal sulcus (IPS) and right lateral occipital complex (LOC) were specifically involved in the Poggendorff illusion induced by the illusory contour. Functional implications of the above findings were further discussed. PMID:26956926

  13. Intonation contour in synchronous speech

    NASA Astrophysics Data System (ADS)

    Wang, Bei; Cummins, Fred

    2003-10-01

    Synchronous Speech (Syn-S), obtained by having pairs of speakers read a prepared text together, has been shown to result in interesting properties in the temporal domain, especially in the reduction of inter-speaker variability in supersegmental timing [F. Cummins, ARLO 3, 7-11 (2002)]. Here we investigate the effect of synchronization among speakers on the intonation contour, with a view to informing models of intonation. Six pairs of speakers (all females) read a short text (176 words) both synchronously and solo. Results show that (1) the pitch accent height above a declining baseline is reduced in Syn-S, compared with solo speech, while the pitch accent location is consistent across speakers in both conditions; (2) in contrast to previous findings on duration matching, there is an asymmetry between speakers, with one speaker exerting a stronger influence on the observed intonation contour than the other; (3) agreement on the boundaries of intonational phrases is greater in Syn-S and intonation contours are well matched from the first syllable of the phrase and throughout.

  14. What is in a contour map? A region-based logical formalization of contour semantics

    USGS Publications Warehouse

    Usery, E. Lynn; Hahmann, Torsten

    2015-01-01

    This paper analyses and formalizes contour semantics in a first-order logic ontology that forms the basis for enabling computational common sense reasoning about contour information. The elicited contour semantics comprises four key concepts – contour regions, contour lines, contour values, and contour sets – and their subclasses and associated relations, which are grounded in an existing qualitative spatial ontology. All concepts and relations are illustrated and motivated by physical-geographic features identifiable on topographic contour maps. The encoding of the semantics of contour concepts in first-order logic and a derived conceptual model as basis for an OWL ontology lay the foundation for fully automated, semantically-aware qualitative and quantitative reasoning about contours.

  15. The Role of Neighborhood in Urban Black Adolescent Marijuana Use*

    PubMed Central

    Reboussin, Beth A.; Green, Kerry M.; Milam, Adam J.; Furr-Holden, Debra M.; Johnson, Renee M.; Ialongo, Nicholas S.

    2015-01-01

    Background The present study examined the influence of neighborhood factors on transitions in marijuana involvement during adolescence in a sample of primarily low-income, urban Black youth. Methods 556 Black adolescents were interviewed annually beginning in first grade as part of a longitudinal study. Latent class analysis (LCA) was used to examine stages of marijuana involvement from 6th to 9th grades. The influence of neighborhood disorder, drug activity, violent crime, safety and disadvantage on transitions in marijuana involvement was tested using latent transition analysis (LTA). Results There was evidence for three stages of involvement: no involvement, offered, and use and problems. Involvement increased steadily during adolescence with a slightly greater risk to transition from offers to use between 6th and 7th grades. Neighborhood disorder (AOR=1.04, CI=1.00, 1.08), drug activity (AOR=1.12, CI=1.02, 1.22) and disadvantage (AOR=1.44, CI=1.10, 1.92) were associated with the transition from marijuana offers to use and problems. Neighborhood disorder (AOR=1.07, CI=1.02, 1.11), drug activity (AOR=1.19, CI=1.10, 1.29) and violent crime (AOR=1.17, CI=1.03, 1.32) were associated with transitioning rapidly from no involvement to use and problems. Conclusions Understanding how neighborhoods could be organized and provided with supports to discourage marijuana use and promote non-drug using behaviors should be an important goal of any prevention program in low-income, urban Black neighborhoods. Enhancing citizen participation and mobilization to address the social processes of neighborhood disorder has the potential to reduce marijuana involvement in these neighborhoods. PMID:26162651

  16. Early processing in human LOC is highly responsive to illusory contours but not to salient regions

    PubMed Central

    Shpaner, Marina; Murray, Micah M.; Foxe, John J.

    2011-01-01

    Human electrophysiological studies support a model whereby sensitivity to so-called illusory contour stimuli is first seen within the lateral occipital complex. A challenge to this model posits that the lateral occipital complex is a general site for crude region-based segmentation, based on findings of equivalent hemodynamic activations in the lateral occipital complex to illusory contour and so-called salient region stimuli, a stimulus class that lacks the classic bounding contours of illusory contours. Using high-density electrical mapping of visual evoked potentials, we show that early lateral occipital cortex activity is substantially stronger to illusory contour than to salient region stimuli, while later lateral occipital complex activity is stronger to salient region than to illusory contour stimuli. Our results suggest that equivalent hemodynamic activity to illusory contour and salient region stimuli likely reflects temporally integrated responses, a result of the poor temporal resolution of hemodynamic imaging. The temporal precision of visual evoked potentials is critical for establishing viable models of completion processes and visual scene analysis. We propose that crude spatial segmentation analyses, which are insensitive to illusory contours, occur first within dorsal visual regions, not lateral occipital complex, and that initial illusory contour sensitivity is a function of the lateral occipital complex. PMID:19895562

  17. The neighborhood effects of foreclosure

    NASA Astrophysics Data System (ADS)

    Leonard, Tammy; Murdoch, James C.

    2009-12-01

    Neighborhood quality is an important attribute of housing yet its value is rarely known to researchers. We argue that changes in nearby foreclosures reveal changes in neighborhood quality. Thus estimates of the hedonic price of nearby foreclosures provide a glimpse of values that people hold for local neighborhood quality. The empirical models include controls for both spatial dependence in housing prices and in the errors. The estimates indicate that nearby foreclosures produce externalities that are capitalized into home prices—an additional foreclosure within 250 feet of a sale negatively impacts selling price by approximately 1,666, ceteris paribus.

  18. Collateral Consequences of Violence in Disadvantaged Neighborhoods

    ERIC Educational Resources Information Center

    Harding, David J.

    2009-01-01

    Using data from Add Health, this study investigates the role of neighborhood violence in mediating the effects of neighborhood disadvantage on high school graduation and teenage pregnancy. Results show that neighborhood violence is a strong predictor of both outcomes, net of individual, family, community and school controls. Neighborhood violence…

  19. Measuring Physical Neighborhood Quality Related to Health

    PubMed Central

    Rollings, Kimberly A.; Wells, Nancy M.; Evans, Gary W.

    2015-01-01

    Although sociodemographic factors are one aspect of understanding the effects of neighborhood environments on health, equating neighborhood quality with socioeconomic status ignores the important role of physical neighborhood attributes. Prior work on neighborhood environments and health has relied primarily on level of socioeconomic disadvantage as the indicator of neighborhood quality without attention to physical neighborhood quality. A small but increasing number of studies have assessed neighborhood physical characteristics. Findings generally indicate that there is an association between living in deprived neighborhoods and poor health outcomes, but rigorous evidence linking specific physical neighborhood attributes to particular health outcomes is lacking. This paper discusses the methodological challenges and limitations of measuring physical neighborhood environments relevant to health and concludes with proposed directions for future work. PMID:25938692

  20. Neuronal oscillations form parietal/frontal networks during contour integration

    PubMed Central

    Castellano, Marta; Plöchl, Michael; Vicente, Raul; Pipa, Gordon

    2014-01-01

    The ability to integrate visual features into a global coherent percept that can be further categorized and manipulated are fundamental abilities of the neural system. While the processing of visual information involves activation of early visual cortices, the recruitment of parietal and frontal cortices has been shown to be crucial for perceptual processes. Yet is it not clear how both cortical and long-range oscillatory activity leads to the integration of visual features into a coherent percept. Here, we will investigate perceptual grouping through the analysis of a contour categorization task, where the local elements that form contour must be linked into a coherent structure, which is then further processed and manipulated to perform the categorization task. The contour formation in our visual stimulus is a dynamic process where, for the first time, visual perception of contours is disentangled from the onset of visual stimulation or from motor preparation, cognitive processes that until now have been behaviorally attached to perceptual processes. Our main finding is that, while local and long-range synchronization at several frequencies seem to be an ongoing phenomena, categorization of a contour could only be predicted through local oscillatory activity within parietal/frontal sources, which in turn, would synchronize at gamma (>30 Hz) frequency. Simultaneously, fronto-parietal beta (13–30 Hz) phase locking forms a network spanning across neural sources that are not category specific. Both long range networks, i.e., the gamma network that is category specific, and the beta network that is not category specific, are functionally distinct but spatially overlapping. Altogether, we show that a critical mechanism underlying contour categorization involves oscillatory activity within parietal/frontal cortices, as well as its synchronization across distal cortical sites. PMID:25165437

  1. Neighborhood Schools and Racial Segregation

    ERIC Educational Resources Information Center

    Kelleher, Daniel T.

    1975-01-01

    Neighborhood school concept and racially segregated residential patterns account for most of the segregation in American public schools today. The focus of this article will be to explain the reasons for residential segregation. (Author/RK)

  2. Brightness alteration with interweaving contours

    PubMed Central

    Roncato, Sergio

    2012-01-01

    Chromatic induction is observed whenever the perceived colour of a target surface shifts towards the hue of a neighbouring surface. Some vivid manifestations may be seen in a white background where thin coloured lines have been drawn (assimilation) or when lines of different colours are collinear (neon effect) or adjacent (watercolour) to each other. This study examines a particular colour induction that manifests in concomitance with an opposite effect of colour saturation (or anti-spread). The two phenomena can be observed when a repetitive pattern is drawn in which outline thin contours intercept wider contours or surfaces, colour spreading appear to fill the surface occupied by surfaces or thick lines whereas the background traversed by thin lines is seen as brighter or filled of a saturated white. These phenomena were first observed by Bozzi (1975) and Kanizsa (1979) in figural conditions that did not allow them to document their conjunction. Here we illustrate various manifestations of this twofold phenomenon and compare its effects with the known effects of brightness and colour induction. Some conjectures on the nature of these effects are discussed. PMID:23483806

  3. Antenna surface contour control system

    NASA Technical Reports Server (NTRS)

    Ahl, Elvin L. (Inventor); Miller, James B. (Inventor)

    1989-01-01

    The invention is a system for automatically controlling the surface contour of a deployable and restowable antenna having a mesh reflector surface supported by a circular, folding hoop affixed to a central, telescoping column. The antenna, when deployed, forms a quad-aperture reflector with each quadrant of the mesh surface shaped to provide an offset parabolic radio frequency (RF) reflector. The hoop is supported and positioned by quartz support cords attached to the top of a column and by lower graphite hoop control cords that extend between the hoop and base of the column. The antenna, an RF reflective surface, is a gold plated molybdenum wire mesh supported on a graphite cord truss structure that includes the hoop control cords and a plurality of surface control cords attached at selected points on the surface and to the base of the column. The contour of the three-dimensional surface of the antenna is controlled by selectively adjusting the lengths of the surface control cords and the graphite hoop control cords by means of novel actuator assemblies that automatically sense and change the lengths of the lower hoop control cords and surface control cords.

  4. Phoenix's New Neighborhood

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The center of the red circle on this map shows where NASA's Phoenix Mars Lander eased down to the surface of Mars, at approximately 68 degrees north latitude, 234 degrees east longitude. Before Phoenix landed, engineers had predicted it would land within the blue ellipse.

    Phoenix touched down on the Red Planet at 4:53 p.m. Pacific Time (7:53 p.m. Eastern Time), May 25, 2008, in an arctic region called Vastitas Borealis.

    The map shows a color-coded interpretation of geomorphic units categories based on the surface textures and contours. The geomorphic mapping is overlaid on a shaded relief map based on data from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor orbiter.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  5. Neighborhood, Family, and Work: Influences on the Premarital Behaviors of Adolescent Males.

    ERIC Educational Resources Information Center

    Ku, Leighton; And Others

    1993-01-01

    Analysis of national survey data suggests that level of sexual activity and likelihood of paternity among adolescent males are related to personal financial resources and employment but also to neighborhood unemployment. Discusses associations of sexual activity, contraceptive use, and paternity with personal and neighborhood race/ethnicity,…

  6. Development of a 15-Item Scale to Measure Parental Perceptions of Their Neighborhood

    ERIC Educational Resources Information Center

    Quigg, Robin; Gray, Andrew; Reeder, Anthony Ivor; Holt, Alec; Waters, Debra L.

    2015-01-01

    Socioecological theory suggests that there are a range of influences that affect the physical activity levels of children, including parents' perceptions of the neighborhood. A questionnaire instrument to quantify parental neighborhood perceptions was developed for the Location of Children's Activity in Their Environment study as a…

  7. Projection moire for remote contour analysis

    NASA Technical Reports Server (NTRS)

    Doty, J. L.

    1983-01-01

    Remote projection and viewing of moire contours are examined analytically for a system employing separate projection and viewing optics, with specific attention paid to the practical limitations imposed by the optical systems. It is found that planar contours are possible only when the optics are telecentric (exit pupil at infinity) but that the requirement for spatial separability of the contour fringes from extraneous fringes is independent of the specific optics and is a function only of the angle separating the two optic axes. In the nontelecentric case, the contour separation near the object is unchanged from that of the telecentric case, although the contours are distorted into low-eccentricity (near-circular) ellipses. Furthermore, the minimum contour spacing is directly related to the depth of focus through the resolution of the optics.

  8. Contouring variability of human- and deformable-generated contours in radiotherapy for prostate cancer

    NASA Astrophysics Data System (ADS)

    Gardner, Stephen J.; Wen, Ning; Kim, Jinkoo; Liu, Chang; Pradhan, Deepak; Aref, Ibrahim; Cattaneo, Richard, II; Vance, Sean; Movsas, Benjamin; Chetty, Indrin J.; Elshaikh, Mohamed A.

    2015-06-01

    This study was designed to evaluate contouring variability of human-and deformable-generated contours on planning CT (PCT) and CBCT for ten patients with low-or intermediate-risk prostate cancer. For each patient in this study, five radiation oncologists contoured the prostate, bladder, and rectum, on one PCT dataset and five CBCT datasets. Consensus contours were generated using the STAPLE method in the CERR software package. Observer contours were compared to consensus contour, and contour metrics (Dice coefficient, Hausdorff distance, Contour Distance, Center-of-Mass [COM] Deviation) were calculated. In addition, the first day CBCT was registered to subsequent CBCT fractions (CBCTn: CBCT2-CBCT5) via B-spline Deformable Image Registration (DIR). Contours were transferred from CBCT1 to CBCTn via the deformation field, and contour metrics were calculated through comparison with consensus contours generated from human contour set. The average contour metrics for prostate contours on PCT and CBCT were as follows: Dice coefficient—0.892 (PCT), 0.872 (CBCT-Human), 0.824 (CBCT-Deformed); Hausdorff distance—4.75 mm (PCT), 5.22 mm (CBCT-Human), 5.94 mm (CBCT-Deformed); Contour Distance (overall contour)—1.41 mm (PCT), 1.66 mm (CBCT-Human), 2.30 mm (CBCT-Deformed); COM Deviation—2.01 mm (PCT), 2.78 mm (CBCT-Human), 3.45 mm (CBCT-Deformed). For human contours on PCT and CBCT, the difference in average Dice coefficient between PCT and CBCT (approx. 2%) and Hausdorff distance (approx. 0.5 mm) was small compared to the variation between observers for each patient (standard deviation in Dice coefficient of 5% and Hausdorff distance of 2.0 mm). However, additional contouring variation was found for the deformable-generated contours (approximately 5.0% decrease in Dice coefficient and 0.7 mm increase in Hausdorff distance relative to human-generated contours on CBCT). Though deformable contours provide a reasonable starting point for contouring on

  9. Contoured insulation window for evacuated solar collector

    SciTech Connect

    Coppola, F. T.; Lentz, W. P.; Vandewoestine, R. V.

    1980-02-05

    An insulating contoured window is provided for use with an enclosed chamber such as an evacuated flat plate solar heat collector with the contoured solar window being of minimum thickness and supported solely about its peripheral edge portions. The window is contoured in both its longitudinal and transverse directions, such that in its longitudinal direction the window is composed of a plurality of sinusoidal corrugations whereas in its transverse direction the peaks of such corrugations are contoured in the form of paraboloids so that the structure may withstand the forces generated thereon by the atmosphere.

  10. Creation of digital contours that approach the characteristics of cartographic contours

    USGS Publications Warehouse

    Tyler, Dean J.; Greenlee, Susan K.

    2012-01-01

    The capability to easily create digital contours using commercial off-the-shelf (COTS) software has existed for decades. Out-of-the-box raw contours are suitable for many scientific applications without pre- or post-processing; however, cartographic applications typically require additional improvements. For example, raw contours generally require smoothing before placement on a map. Cartographic contours must also conform to certain spatial/logical rules; for example, contours may not cross waterbodies. The objective was to create contours that match as closely as possible the cartographic contours produced by manual methods on the 1:24,000-scale, 7.5-minute Topographic Map series. This report outlines the basic approach, describes a variety of problems that were encountered, and discusses solutions. Many of the challenges described herein were the result of imperfect input raster elevation data and the requirement to have the contours integrated with hydrographic features from the National Hydrography Dataset (NHD).

  11. Neighborhood Violence and Adolescent Friendships

    PubMed Central

    Harding, David J.

    2010-01-01

    This paper investigates the social consequences of neighborhood violence. Using ego-centered friendship network data from the National Longitudinal Study of Adolescent Health, a survey of adolescents in the United States in the mid-1990s, it examines the relationship between neighborhood violence and the quantity, closeness, and composition of adolescent same-sex friendships. Though neighborhood violence is unrelated to quantity and closeness net of individual and family characteristics, it predicts boys’ friendships with individuals who no longer attend school (who are presumably older or have dropped out of school) and predicts boys’ and girls’ friendships with individuals who attend other schools. These results are consistent with the theory that violence and fear of victimization focus adolescents’ social attention on their neighborhoods and lead them to develop friendships with individuals who can help them to stay safe. By structuring who adolescents interact with, neighborhood violence may play a role in determining the cultural messages and ideals to which they are exposed. PMID:20428462

  12. Body Contouring After Bariatric Surgery.

    PubMed

    Ellison, Jo M; Steffen, Kristine J; Sarwer, David B

    2015-11-01

    Individuals who undergo bariatric surgery generally experience rapid and dramatic weight loss. While the weight loss typically confers significant health benefits, an undesirable consequence is often excessive quantities of hanging, surplus skin. Some patients undergo body-contouring surgery (BCS) in order to improve health, mobility, appearance and psychological adjustment. While the majority of post-bariatric patients desire BCS in one or more body regions, a small percentage of patients receive such surgeries. Lack of knowledge about procedures, cost and (in the USA and several other countries) difficulty obtaining insurance reimbursement likely prevents many patients from undergoing BCS. Those who do undergo BCS appear to be at heightened risk for wound-healing complications. Despite these complications, the majority of patients report satisfactory BCS outcomes. The extant literature in this area provides a great deal of information about these issues; nevertheless, additional research is needed to further inform clinical management and improve patient outcomes. PMID:26395601

  13. Sodium Deoxycholate for Submental Contouring.

    PubMed

    Humphrey, S; Beleznay, K; Beleznay, J D A

    2016-09-01

    The chin and jaw line are integral parts of an individual's aesthetic profile, and the presence of submental fat detracts from this and can lead to displeasure with one's facial appearance. While liposuction and cosmetic surgery are regarded as the gold standard in treating submental fat, surgical intervention is not appealing to all patients and has potential surgical complications including longer recovery, and contour irregularities. Despite ample advances in aesthetic medicine to enhance the appearance of the face, very little is available in non-invasive options to reduce submental fat that has been supported by robust evidence. ATX-101, a proprietary formulation of deoxycholic acid that is synthetically derived, has been extensively explored in a vigorous clinical development program that has established the safety and efficacy of the injectable. It has recently received approval by regulatory authorities in Canada (Belkyra™) and the US (Kybella®) for the treatment of submental fat. PMID:27603325

  14. Cortical Contributions to Impaired Contour Integration in Schizophrenia

    PubMed Central

    Silverstein, Steven M.; Harms, Michael P.; Carter, Cameron S.; Gold, James M.; Keane, Brian P.; MacDonald, Angus; Ragland, J. Daniel; Barch, Deanna M.

    2015-01-01

    Objectives Visual perceptual organization impairments in schizophrenia (SCZ) are well established, but their neurobiological bases are not. The current study used the previously validated Jittered Orientation Visual Integration (JOVI) task, along with fMRI, to examine the neural basis of contour integration (CI), and its impairment in SCZ. CI is an aspect of perceptual organization in which multiple distinct oriented elements are grouped into a single continuous boundary or shape. Methods On the JOVI, five levels of orientational jitter were added to non-contiguous closed contour elements embedded in background noise to progressively increase the difficulty in perceiving contour elements as left- or right-pointing ovals. Multi-site fMRI data were analyzed for 56 healthy control subjects and 47 people with SCZ. Results SCZ patients demonstrated poorer CI, and this was associated with increased activation in regions involved in global shape processing and visual attention, namely the lateral occipital complex and superior parietal lobules. There were no brain regions where controls demonstrated more activation than patients. Conclusions CI impairment in this sample of outpatients with SCZ was related to excessive activation in regions associated with object processing and allocation of visual-spatial attention. There was no evidence for basic impairments in contour element linking in the fMRI data. The latter may be limited to poor outcome patients, where more extensive structural and functional changes in the occipital lobe have been observed. PMID:26160288

  15. Neighborhood Dynamics of Urban Violence

    PubMed Central

    Chavez, Jorge M.; Griffiths, Elizabeth

    2013-01-01

    Social disorganization is the dominant framework linking neighborhood patterns of immigration to local rates of crime and violence despite inconsistent findings and evidence to the contrary. Using tract-level census data from 1970 to 1990 and Chicago homicide data from 1980 to 1995, this study explores whether and how the changing face of immigration is (un)related to homicide patterns within the contemporary urban environment. The results show that stable and consistent growth in foreign born is not associated with neighborhood trends in violence, whereas growth in recent arrivals occurs almost exclusively within the safest neighborhoods of the city. This research highlights the need to distinguish recent waves of immigrants/migrants from their historic counterparts. PMID:24222722

  16. Interval and Contour Processing in Autism

    ERIC Educational Resources Information Center

    Heaton, Pamela

    2005-01-01

    High functioning children with autism and age and intelligence matched controls participated in experiments testing perception of pitch intervals and musical contours. The finding from the interval study showed superior detection of pitch direction over small pitch distances in the autism group. On the test of contour discrimination no group…

  17. Tongue Motion Averaging from Contour Sequences

    ERIC Educational Resources Information Center

    Li, Min; Kambhamettu, Chandra; Stone, Maureen

    2005-01-01

    In this paper, a method to get the best representation of a speech motion from several repetitions is presented. Each repetition is a representation of the same speech captured at different times by sequence of ultrasound images and is composed of a set of 2D spatio-temporal contours. These 2D contours in different repetitions are time aligned…

  18. Auditory and Visual Similarity of Pitch Contours.

    ERIC Educational Resources Information Center

    Hermes, Dik J.

    1998-01-01

    In two experiments, five phoneticians rated the dissimilarity of two pitch contours to investigate whether important audible differences would correspond with visually conspicuous differences between displayed pitch contours. Results indicate that visual feedback may be very effective in intonation training if auditorily relevant features of pitch…

  19. Measuring the Perceptual Similarity of Pitch Contours.

    ERIC Educational Resources Information Center

    Hermes, Dik J.

    1998-01-01

    This study investigated the effectiveness of four different methods for measuring the similarity of pitch contours. The correlation coefficient between two normalized contours was the best method; however, if pitch range is important, the mean distance and the root-mean-square distance should be considered first in automatic training in…

  20. Neighborhood Centre Project, Hull, September 1982 - October 1983.

    ERIC Educational Resources Information Center

    Rice, Margaret; Doyle, Patrick

    Brief reports provided in this paper document aspects of a neighborhood-center project in Hull, England. The project was aimed primarily at facilitating parent/community involvement in the education of very young children through the establishment of parent activity groups. Beginning with activity groups such as mother/toddler clubs, a community…

  1. Neighborhood effects on an individual's health using neighborhood measurements developed by factor analysis and cluster analysis.

    PubMed

    Li, Yu-Sheng; Chuang, Ying-Chih

    2009-01-01

    This study suggests a multivariate-structural approach combining factor analysis and cluster analysis that could be used to examine neighborhood effects on an individual's health. Data were from the Taiwan Social Change Survey conducted in 1990, 1995, and 2000. In total, 5,784 women and men aged over 20 years living in 428 neighborhoods were interviewed. Participants' addresses were geocoded with census data for measuring neighborhood-level characteristics. The factor analysis was applied to identify neighborhood dimensions, which were used as entities in the cluster analysis to generate a neighborhood typology. The factor analysis generated three neighborhood dimensions: neighborhood education, age structure, and neighborhood family structure and employment. The cluster analysis generated six types of neighborhoods with combinations of the three neighborhood dimensions. Multilevel binomial regression models were used to assess the effects of neighborhoods on an individual's health. The results showed that the biggest health differences were between two neighborhood types: (1) the highest concentration of inhabitants younger than 15 years, a moderate education level, and a moderate level of single-parent families and (2) the highest educational level, a median level of single-parent families, and a median level of elderly concentrations. Individuals living in the first type had significantly higher chances of having functional limitations and poor self-rated health than the individuals in the second neighborhood type. Our study suggests that the multivariate-structural approach improves neighborhood measurements by addressing neighborhood diversity and examining how an individual's health varies in different neighborhood contexts. PMID:18629650

  2. Neighborhood Newspapers and Neighborhood Leaders: Influences on Agenda Setting and Definitions of Issues.

    ERIC Educational Resources Information Center

    Gaziano, Cecilie

    Assuming that neighborhood newspapers and neighborhood leaders are among the most important influences on neighborhood residents' issue agendas and definitions of issues, a study examined some of these influences by interviewing a random sample of 239 residents of a low income, urban neighborhood in Minneapolis. In addition, a purposive sample of…

  3. Sweet Mothers and Gangbangers: Managing Crime in a Black Middle-Class Neighborhood.

    ERIC Educational Resources Information Center

    Pattillo, Mary E.

    1998-01-01

    Ethnographic data from a black middle-class Chicago neighborhood indicate that dense social networks fostered by residential stability facilitate informal supervision of neighborhood youth and enhance formal crime-prevention activities. Nevertheless, inclusion of gang members and drug dealers in networks of law-abiding kin and neighbors thwarts…

  4. Neighborhood Variation in Gang Member Concentrations

    ERIC Educational Resources Information Center

    Katz, Charles M.; Schnebly, Stephen M.

    2011-01-01

    This study examines the relationship between neighborhood structure, violent crime, and concentrations of gang members at the neighborhood level. We rely on official police gang list data, police crime data, and two waves of decennial census data characterizing the socioeconomic and demographic conditions of 93 neighborhoods in Mesa, Arizona.…

  5. Schools, Neighborhood Risk Factors, and Crime

    ERIC Educational Resources Information Center

    Willits, Dale; Broidy, Lisa; Denman, Kristine

    2013-01-01

    Prior research has identified a link between schools (particularly high schools) and neighborhood crime rates. However, it remains unclear whether the relationship between schools and crime is a reflection of other criminogenic dynamics at the neighborhood level or whether schools influence neighborhood crime patterns independently of other…

  6. Neighborhood Racial Isolation, Disorder and Obesity

    ERIC Educational Resources Information Center

    Chang, Virginia W.; Hillier, Amy E.; Mehta, Neil K.

    2009-01-01

    Recent research suggests that racial residential segregation may be detrimental to health. This study investigates the influence of neighborhood racial isolation on obesity and considers the role of neighborhood disorder as a mediator in this relationship. For the city of Philadelphia, we find that residence in a neighborhood with high black…

  7. Neighborhood Characteristics, Parenting, and Children's Safety

    ERIC Educational Resources Information Center

    McDonell, James R.

    2007-01-01

    Recent studies highlight the importance of neighborhood context for child and family well-being. Yet challenges to research on neighborhood effects remain; research on young children is sparse, as is research on neighborhood effects on parenting. Measurement also continues to challenge researchers, particularly in devising non-invasive means of…

  8. Neighborhood School Blends In Well.

    ERIC Educational Resources Information Center

    American School and University, 1982

    1982-01-01

    Design considerations for the Haverhill Elementary School in Fort Wayne (Indiana) were that it blend in with the residential neighborhood and be extremely energy effective. By dividing the building into four pods with low hip roofs, and by the extensive use of insulation, both requirements were met. (Author/MLF)

  9. Rural neighborhoods and child aggression.

    PubMed

    Bowen, Natasha K; Wretman, Christopher J

    2014-12-01

    Structural equation modeling with latent variables was used to evaluate the direct and mediated effects of a neighborhood risk factor (negative teen behaviors) on the parent-report aggressive behavior of 213 students in grades 3 through 5 attending a school in a low-income, rural community. Contagion and social control hypotheses were examined as well as hypotheses about whether the neighborhood served as a microsystem or exosystem for rural pre-adolescents. Analyses took into account the clustering of students and ordinal nature of the data. Findings suggest that rural neighborhoods may operate as both a microsystem and exosystem for children, with direct contagion effects on their aggressive behaviors as well as indirect social control effects through parenting practices. Direct effects on aggression were also found for parenting practices and child reports of friends' negative behaviors. Pre-adolescence may be a transitional stage, when influences of the neighborhood on child behavior begin to compete with influences of caregivers. Findings can inform the timing and targets of violence prevention in rural communities. PMID:25205545

  10. Invited Commentary: Taking Advantage of Time-Varying Neighborhood Environments

    PubMed Central

    Lovasi, Gina S.; Goldsmith, Jeff

    2014-01-01

    Neighborhood built environment characteristics may encourage physical activity, but previous literature on the topic has been critiqued for its reliance on cross-sectional data. In this issue of the Journal, Knuiman et al. (Am J Epidemiol. 2014;180(5):453–461) present longitudinal analyses of built environment characteristics as predictors of neighborhood transportation walking. We take this opportunity to comment on self-selection, exposure measurement, outcome form, analyses, and future directions. The Residential Environments (RESIDE) Study follows individuals as they relocate into new housing. The outcome, which is neighborhood transportation walking, has several important limitations with regards to public health relevance, dichotomization, and potential bias. Three estimation strategies were pursued: marginal modeling, random-effects modeling, and fixed-effects modeling. Knuiman et al. defend fixed-effects modeling as the one that most effectively controls for unmeasured time-invariant confounders, and it will do so as long as confounders have a constant effect over time. Fixed-effects modeling requires no distributional assumptions regarding the heterogeneity of subject-specific effects. Associations of time-varying neighborhood characteristics with walking are interpreted at the subject level for both fixed- and random-effects models. Cross-sectional data have set the stage for the next generation of neighborhood research, which should leverage longitudinal changes in both place and health behaviors. Careful interpretation is warranted as longitudinal data become available for analysis. PMID:25117659

  11. Determination of the absolute contours of optical flats

    NASA Technical Reports Server (NTRS)

    Primak, W.

    1969-01-01

    Emersons procedure is used to determine true absolute contours of optical flats. Absolute contours of standard flats are determined and a comparison is then made between standard and unknown flats. Contour differences are determined by deviation of Fizeau fringe.

  12. Differential contribution of early visual areas to the perceptual process of contour processing.

    PubMed

    Schira, Mark M; Fahle, Manfred; Donner, Tobias H; Kraft, Antje; Brandt, Stephan A

    2004-04-01

    We investigated contour processing and figure-ground detection within human retinotopic areas using event-related functional magnetic resonance imaging (fMRI) in 6 healthy and naïve subjects. A figure (6 degrees side length) was created by a 2nd-order texture contour. An independent and demanding foveal letter-discrimination task prevented subjects from noticing this more peripheral contour stimulus. The contour subdivided our stimulus into a figure and a ground. Using localizers and retinotopic mapping stimuli we were able to subdivide each early visual area into 3 eccentricity regions corresponding to 1) the central figure, 2) the area along the contour, and 3) the background. In these subregions we investigated the hemodynamic responses to our stimuli and compared responses with or without the contour defining the figure. No contour-related blood oxygenation level-dependent modulation in early visual areas V1, V3, VP, and MT+ was found. Significant signal modulation in the contour subregions of V2v, V2d, V3a, and LO occurred. This activation pattern was different from comparable studies, which might be attributable to the letter-discrimination task reducing confounding attentional modulation. In V3a, but not in any other retinotopic area, signal modulation corresponding to the central figure could be detected. Such contextual modulation will be discussed in light of the recurrent processing hypothesis and the role of visual awareness. PMID:14668291

  13. Neighborhood Amenities and Mobility in Older Adults

    PubMed Central

    Rosso, Andrea L.; Grubesic, Tony H.; Auchincloss, Amy H.; Tabb, Loni P.; Michael, Yvonne L.

    2013-01-01

    Diversity of neighborhood amenities may promote the mobility of older adults. A 2010 community-based sample of 510 adults aged ≥65 years in Philadelphia, Pennsylvania, and geospatial data from the Esri Business Analyst database (Esri, Inc., Redlands, California) were used to assess associations of neighborhood amenity diversity with mobility. Neighborhoods were defined by census tract, and diversity of amenities was derived by using the Leadership in Energy and Environmental Design's neighborhood development index (US Green Building Council, Washington, DC). Generalized estimating equations adjusted for demographic, socioeconomic, and neighborhood characteristics were used to estimate differences in mobility score by tertile of amenity diversity. Analyses were stratified by participants' routine travel habits (stayed at home, stayed in home zip code, or traveled beyond home zip code). We found that for those who spent most of their time in their home neighborhoods, mobility scores (from the Life-Space Assessment, which ranges from 0 to 104 points) were 8.3 points higher (95% confidence interval: 0.1, 16.6) among those who lived in neighborhoods with the most amenity diversity compared with those who lived in neighborhoods with the least amenity diversity. No significant associations between amenity diversity and mobility were observed for those who did not leave home or who regularly traveled outside their neighborhoods. Neighborhoods with a high diversity of amenities may be important promoters of mobility in older adults who do not routinely travel outside their neighborhoods. PMID:23666814

  14. Collateral Consequences of Violence in Disadvantaged Neighborhoods

    PubMed Central

    Harding, David J.

    2009-01-01

    Using data from Addhealth, this study investigates the role of neighborhood violence in mediating the effects of neighborhood disadvantage on high school graduation and teenage pregnancy. Results show that neighborhood violence is a strong predictor of both outcomes, net of individual, family, community, and school controls. Neighborhood violence accounts for almost half the conditional association between neighborhood disadvantage and high school graduation among males and almost all of the association among females. Violence also accounts for about one fifth of the conditional association between disadvantage and teenage pregnancy among adolescents of both genders. Violence is a critical social characteristic of disadvantaged neighborhoods, one that explains a sizable portion of the effects of growing up in such neighborhoods. PMID:20676355

  15. The Physiological Expression of Living in Disadvantaged Neighborhoods for Youth

    ERIC Educational Resources Information Center

    Brenner, Allison B.; Zimmerman, Marc A.; Bauermeister, Jose A.; Caldwell, Cleopatra H.

    2013-01-01

    Evidence suggests that the consequences of chronic exposure to stressors extend beyond psychological effects, and that adolescents living in socio-economically disadvantaged neighborhoods may experience an accumulation of exposure to stressors that wears down the physical systems in the body, resulting in hyper-activation of the stress response.…

  16. Adult Perceptions of Neighborhood: Links to Youth Engagement

    ERIC Educational Resources Information Center

    Duke, Naomi N.; Borowsky, Iris W.; Pettingell, Sandra L.

    2012-01-01

    Context is important in facilitating healthy youth development. The purpose of this study was to examine the relationship between adult perception of neighborhood and youth engagement in organized activities. This study is a secondary data analysis of 64,076 parents and guardians of school-age youth and adolescents (6-17 years), participating in…

  17. The Neighborhood and American Society. (Controversial Issues Kit" No. 1.

    ERIC Educational Resources Information Center

    Risinger, C. Frederick

    This kit provides a summary of a scholarly paper, discussion questions, and activities to promote constructive debate between scholars and ethnic and minority groups about the changing role of the neighborhood in American society. The materials focus on the Chicago area, but the issues and problems apply to any urban area. The paper traces the…

  18. Facilitative Orthographic Neighborhood Effects: The SERIOL Model Account

    ERIC Educational Resources Information Center

    Whitney, Carol; Lavidor, Michal

    2005-01-01

    A large orthographic neighborhood (N) facilitates lexical decision for central and left visual field/right hemisphere (LVF/RH) presentation, but not for right visual field/left hemisphere (RVF/LH) presentation. Based on the SERIOL model of letter-position encoding, this asymmetric N effect is explained by differential activation patterns at the…

  19. Potholes and (In) Geography: Studying State Shapes in the Neighborhood

    ERIC Educational Resources Information Center

    Albert, Donald

    2015-01-01

    This activity is an amusing, but serious exploration into the idea of shapes for grades 4-8. Its purpose is to encourage students to begin thinking about shapes using concrete (and asphalt) examples from their immediate surroundings (i.e., street, block, neighborhood) while enhancing their mental image of world geography. Rather than allowing all…

  20. Extreme_SeaState_Contour_v1

    2015-10-19

    This software generates environmental contours of extreme sea states using buoy observations of significant wave height and energy period or peak period. The code transforms these observations using principal component analysis (PCA) to create an uncorrelated representation of the data. The subsequent components are modeled using probability distributions and parameter fitting functions. The inverse first-order reliability method (I-FORM) is then applied to these models in order to generate an extreme event contour based on amore » given return period (i.e., 100 years).The subsequent contour is then transformed back into the original input space defined by the variables of interest in order to create an environmental contour of extreme sea states.« less

  1. Extreme_SeaState_Contour_v1

    SciTech Connect

    2015-10-19

    This software generates environmental contours of extreme sea states using buoy observations of significant wave height and energy period or peak period. The code transforms these observations using principal component analysis (PCA) to create an uncorrelated representation of the data. The subsequent components are modeled using probability distributions and parameter fitting functions. The inverse first-order reliability method (I-FORM) is then applied to these models in order to generate an extreme event contour based on a given return period (i.e., 100 years).The subsequent contour is then transformed back into the original input space defined by the variables of interest in order to create an environmental contour of extreme sea states.

  2. Holding fixture for variable-contour parts

    NASA Technical Reports Server (NTRS)

    Haynie, C. C.; Packer, P. N.; Zebus, P. P.

    1979-01-01

    Array of vacuum cups on spindles holds parts for safe machining and other processings. Variable-contour part resting on fixture is held firmly enough for machining, coating, or other mechanical treatment.

  3. Neighborhood Characteristics, Adherence to Walking, and Depressive Symptoms in Midlife African American Women

    PubMed Central

    Zenk, Shannon; Wang, Edward; Oh, April; McDevitt, Judith; Block, Dick; McNeil, Sue; Ju, SuKyung

    2009-01-01

    Abstract Background African American women have more symptoms of depressed mood than white women. Adverse neighborhood conditions may contribute to these symptoms. Although reductions in depressive symptoms with physical activity have been demonstrated in white adults, little research has examined the mental health benefits of physical activity in African American women. Further, it is unknown whether physical activity can offset the effects of living in disadvantaged neighborhoods on depressive symptoms. The purpose of this study was to examine the relationships among neighborhood characteristics, adherence to a physical activity intervention, and change over time in depressive symptoms in midlife African American women. Methods Two hundred seventy-eight women participated in a home-based, 24-week moderate-intensity walking intervention. Either a minimal treatment (MT) or enhanced treatment (ET) version of the intervention was randomly assigned to one of the two community health centers. Walking adherence was measured as the percentage of prescribed walks completed. Objective and perceived measures of neighborhood deterioration and crime were included. Results Adjusting for demographics, body mass index (BMI), and depressive symptoms at baseline, walking adherence and objective neighborhood deterioration were associated with significantly lower depressive symptoms, whereas perceived neighborhood deterioration was associated with significantly higher depressive symptoms at 24 weeks. Conclusions Adherence to walking as well as aspects of the environment may influence depressive symptoms in African American women. In addition to supporting active lifestyles, improving neighborhood conditions may also promote mental health among African American women. PMID:19630546

  4. Cognitive Function in the Community Setting: The Neighborhood as a Source of “Cognitive Reserve”?

    PubMed Central

    Clarke, Philippa J.; Ailshire, Jennifer A.; House, James S.; Morenoff, Jeffrey D.; King, Katherine; Melendez, Robert; Langa, Kenneth M.

    2012-01-01

    Background Existing research has found a positive association between cognitive function and residence in a socioeconomically advantaged neighborhood. Yet, the mechanisms underlying this relationship have not been empirically investigated. This study tests the hypothesis that neighborhood socioeconomic structure is related to cognitive function partly through the availability of neighborhood physical and social resources (e.g. recreational facilities, community centers and libraries), which promote cognitively beneficial activities such as exercise and social integration. Methods Using data from a representative survey of community-dwelling adults in the City of Chicago (N = 949 adults age 50 and over) we assessed cognitive function with a modified version of the Telephone Interview for Cognitive Status (TICS) instrument. Neighborhood socioeconomic structure was derived from US Census indicators. Systematic Social Observation was used to directly document the presence of neighborhood resources on the blocks surrounding each respondent’s residence. Results Using multilevel linear regression, residence in an affluent neighborhood had a net positive effect on cognitive function after adjusting for individual risk factors. For white respondents, the effects of neighborhood affluence operated in part through a greater density of institutional resources (e.g. community centers) that promote cognitively beneficial activities such as physical activity. Stable residence in an elderly neighborhood was associated with higher cognitive function (potentially due to greater opportunities for social interaction with peers), but long term exposure to such neighborhoods was negatively related to cognition. Conclusions Neighborhood resources have the potential to promote “cognitive reserve” for adults who are aging in place in an urban setting. PMID:21515547

  5. Isolating contour information from arbitrary images

    NASA Technical Reports Server (NTRS)

    Jobson, Daniel J.

    1989-01-01

    Aspects of natural vision (physiological and perceptual) serve as a basis for attempting the development of a general processing scheme for contour extraction. Contour information is assumed to be central to visual recognition skills. While the scheme must be regarded as highly preliminary, initial results do compare favorably with the visual perception of structure. The scheme pays special attention to the construction of a smallest scale circular difference-of-Gaussian (DOG) convolution, calibration of multiscale edge detection thresholds with the visual perception of grayscale boundaries, and contour/texture discrimination methods derived from fundamental assumptions of connectivity and the characteristics of printed text. Contour information is required to fall between a minimum connectivity limit and maximum regional spatial density limit at each scale. Results support the idea that contour information, in images possessing good image quality, is (centered at about 10 cyc/deg and 30 cyc/deg). Further, lower spatial frequency channels appear to play a major role only in contour extraction from images with serious global image defects.

  6. Surgical correction of postliposuction contour irregularities.

    PubMed

    Chang, K N

    1994-07-01

    The surgical correction of postliposuction contour irregularities and the results are presented. Postliposuction contour irregularities are classified as major or minor according to the size of the area, severity of the irregularity, difficulty of the correction, visual impact, and the need for dermolipectomy. Methods of correction include (1) liposuction of the area of protuberance, (2) liposuction around the area of depression, (3) simultaneous fat grafting, and (4) dermolipectomy. Results of 22 patients with 43 areas of postliposuction contour irregularities were analyzed. Follow-up ranged from 1 to 4.8 years (mean 2.1 +/- 1.0 years). All patients had corrective liposuction except one, who required medial thigh dermolipectomy. Fat grafting was performed in 19 areas in 9 patients. Average number of operations performed was 1.4 per patient (range 1 to 3). Of 17 areas of minor postliposuction contour irregularities, 8 (47 percent) were improved and 8 (47 percent) were corrected. Of 26 areas of major postliposuction contour irregularities, 17 (65 percent) were improved and 8 (31 percent) were corrected. Of all 43 areas, 25 (58 percent) were improved and 16 (37 percent) were corrected. Overcorrection in two areas (4.7 percent) resulted in minor depressions in 2 patients. Results from 5 patients are presented. In summary, postliposuction contour irregularities were treated with various surgical techniques with a high rate of improvement or correction. PMID:8016225

  7. Negative Life Events Vary by Neighborhood and Mediate the Relation Between Neighborhood Context and Psychological Well-Being

    EPA Science Inventory

    Although a considerable amount of neighborhood research has addressed how fear of negative events may activate stress responses, few studies have noted the potentially embedded nature of negative life events within spatial riskscapes. Co-occurring contextual social and physical h...

  8. Effect of neighborhood stigma on economic transactions

    PubMed Central

    Besbris, Max; Faber, Jacob William; Rich, Peter; Sharkey, Patrick

    2015-01-01

    The hypothesis of neighborhood stigma predicts that individuals who reside in areas known for high crime, poverty, disorder, and/or racial isolation embody the negative characteristics attributed to their communities and experience suspicion and mistrust in their interactions with strangers. This article provides an experimental test of whether neighborhood stigma affects individuals in one domain of social life: economic transactions. To evaluate the neighborhood stigma hypothesis, this study adopts an audit design in a locally organized, online classified market, using advertisements for used iPhones and randomly manipulating the neighborhood of the seller. The primary outcome under study is the number of responses generated by sellers from disadvantaged relative to advantaged neighborhoods. Advertisements from disadvantaged neighborhoods received significantly fewer responses than advertisements from advantaged neighborhoods. Results provide robust evidence that individuals from disadvantaged neighborhoods bear a stigma that influences their prospects in economic exchanges. The stigma is greater for advertisements originating from disadvantaged neighborhoods where the majority of residents are black. This evidence reveals that residence in a disadvantaged neighborhood not only affects individuals through mechanisms involving economic resources, institutional quality, and social networks but also affects residents through the perceptions of others. PMID:25848041

  9. Effect of neighborhood stigma on economic transactions.

    PubMed

    Besbris, Max; Faber, Jacob William; Rich, Peter; Sharkey, Patrick

    2015-04-21

    The hypothesis of neighborhood stigma predicts that individuals who reside in areas known for high crime, poverty, disorder, and/or racial isolation embody the negative characteristics attributed to their communities and experience suspicion and mistrust in their interactions with strangers. This article provides an experimental test of whether neighborhood stigma affects individuals in one domain of social life: economic transactions. To evaluate the neighborhood stigma hypothesis, this study adopts an audit design in a locally organized, online classified market, using advertisements for used iPhones and randomly manipulating the neighborhood of the seller. The primary outcome under study is the number of responses generated by sellers from disadvantaged relative to advantaged neighborhoods. Advertisements from disadvantaged neighborhoods received significantly fewer responses than advertisements from advantaged neighborhoods. Results provide robust evidence that individuals from disadvantaged neighborhoods bear a stigma that influences their prospects in economic exchanges. The stigma is greater for advertisements originating from disadvantaged neighborhoods where the majority of residents are black. This evidence reveals that residence in a disadvantaged neighborhood not only affects individuals through mechanisms involving economic resources, institutional quality, and social networks but also affects residents through the perceptions of others. PMID:25848041

  10. Do neighborhood attributes moderate the relationship between alcohol establishment density and crime?

    PubMed Central

    Erickson, Darin J.; Carlin, Bradley P.; Lenk, Kathleen M.; Quick, Harrison S.; Harwood, Eileen M.; Toomey, Traci L.

    2014-01-01

    Although numerous studies have found a positive association between density of alcohol establishments and various types of crime, few have examined how neighborhood attributes (e.g., schools, parks) could moderate this association. We used data from Minneapolis, Minnesota with neighborhood as the unit of analysis (n = 83). We examined eight types of crime (assault, rape, robbery, vandalism, nuisance crime, public alcohol consumption, driving while intoxicated, underage alcohol possession/consumption) and measured density as total number of establishments per roadway mile. Neighborhood attributes assessed as potential moderators included non-alcohol businesses, schools, parks, religious institutions, neighborhood activism, neighborhood quality, and number of condemned houses. Using Bayesian techniques, we created a model for each crime outcome (accounting for spatial auto-correlation and controlling for relevant demographics) with an interaction term (moderator × density) to test each potential moderating effect. Few interaction terms were statistically significant. Presence of at least one college was the only neighborhood attribute that consistently moderated the density-crime association, with presence of a college attenuating the association between density and three types of crime (assaults, nuisance crime, and public consumption). However, caution should be used when interpreting the moderating effect of college presence because of the small number of colleges in our sample. The lack of moderating effects of neighborhood attributes except for presence of a college suggests that the addition of alcohol establishments to any neighborhood regardless of its other attributes could result in an increase in a wide range of crime. PMID:24337980

  11. How neighborhood disorder increases blood pressure in youth: agonistic striving and subordination

    PubMed Central

    Elder, Gavin J.; Smyth, Joshua M.

    2012-01-01

    Growing evidence links perceptions of neighborhood disorder to adverse health outcomes but little is known about psychological processes that may mediate this association. We tested the hypothesis that two psychological mechanisms—agonistic striving and subordination—mediate the link between perceived neighborhood disorder and hypertension risk in youth. Perceived neighborhood disorder, agonistic striving, subordination experiences, negative affect, obesity, and ambulatory blood pressure during daily activities (48 h) were assessed in a multiethnic sample of 167 low- to middle-income urban adolescents. Path analyses revealed that agonistic striving, subordination, and obesity each independently mediated the association between neighborhood disorder and blood pressure; these variables accounted for 73 % of the shared variance, 42 % of which was explained by agonistic striving. The direct relationship between perceived neighborhood disorder and blood pressure was no longer significant in the presence of these mediators. Negative affect was associated with neighborhood disorder and subordination, but not blood pressure. Agonistic striving proved to be a significant and substantial mediator of the association between perceived neighborhood disorder, blood pressure, and future hypertension risk. New research should seek to clarify the processes by which stressful neighborhoods induce persistent agonistic motives and perceptions of subordination in adolescents. PMID:23229689

  12. The Role of Immigrant Concentration Within and Beyond Residential Neighborhoods in Adolescent Alcohol Use.

    PubMed

    Jackson, Aubrey L; Browning, Christopher R; Krivo, Lauren J; Kwan, Mei-Po; Washington, Heather M

    2016-01-01

    Neighborhoods are salient contexts for youth that shape adolescent development partly through informal social controls on their behavior. This research examines how immigrant concentration within and beyond the residential neighborhood influences adolescent alcohol use. Residential neighborhood immigrant concentration may lead to a cohesive, enclave-like community that protects against adolescent alcohol use. But heterogeneity in the immigrant concentrations characterizing the places residents visit as they engage in routine activities outside of the neighborhood where they live may weaken the social control benefits of the social ties and shared cultural orientations present in enclave communities. This study investigates whether the protective influence of residential neighborhood immigrant concentration on adolescent alcohol consumption diminishes when youth live in communities where residents collectively are exposed to areas with more diverse immigrant concentrations. This study tests this contention by analyzing survey and geographic routine activity space data from the Los Angeles Family and Neighborhood Survey, and the 2000 census. The sample includes 793 adolescents (48.7% female, 16.5% foreign-born Latino, 42.5% US-born Latino, 11.0% black, 30% white/other) between the ages of 12 and 17 who live in 65 neighborhoods in Los Angeles County. Immigrant concentration among these neighborhoods derives primarily from Latin America. The results from multilevel models show that immigrant concentration protects against adolescent alcohol use only when there is low neighborhood-level diversity of exposures to immigrant concentration among the contexts residents visit outside of their residential neighborhood. This research highlights the importance of considering the effects of aggregate exposures to non-home contexts on adolescent wellbeing. PMID:26215378

  13. Male perpetration of teen dating violence: associations with neighborhood violence involvement, gender attitudes, and perceived peer and neighborhood norms.

    PubMed

    Reed, Elizabeth; Silverman, Jay G; Raj, Anita; Decker, Michele R; Miller, Elizabeth

    2011-04-01

    This study aims to examine the link between male perpetration of teen dating violence (TDV) and neighborhood violence, as well as associations with gender attitudes and perceived peer and neighborhood norms related to violence among a sample of urban adolescent boys. Participants of this cross-sectional study (N = 275) were between the ages of 14 and 20 years and recruited from urban community health centers. Crude and adjusted logistic and linear regression models were used to examine TDV perpetration in relation to (a) neighborhood violence involvement, (b) perceptions of peer violence, (c) perceptions of neighborhood violence, and (d) gender attitudes. Slightly more than one in four (28%) boys reported at least one form of TDV perpetration; among boys who have ever had sex, almost half (45%) reported at least one form of TDV perpetration. In logistic and linear regression models adjusted for demographics, boys who reported TDV perpetration were more likely to report involvement in neighborhood violence (odds ratio (OR) = 3.1; 95% confidence interval (CI) = 1.7-5.5), beliefs that their friends have perpetrated TDV (OR = 2.7; 95%CI = 1.4-5.1), perceptions of violent activity within their neighborhood (OR = 3.0; 95%CI = 1.4-6.3), and greater support of traditional gender norms (β = 3.2, p = 0.002). The findings suggest that efforts are needed to address boys' behaviors related to the perpetration of multiple forms of violence and require explicit efforts to reduce perceived norms of violence perpetration as well as problematic gender attitudes (e.g., increasing support for gender equity) across boys' life contexts. PMID:21311987

  14. Racial Diversity and Change in Metropolitan Neighborhoods*

    PubMed Central

    Farrell, Chad R.; Lee, Barrett A.

    2011-01-01

    This study investigates the changing racial diversity and structure of metropolitan neighborhoods. We consider three alternative perspectives about localized racial change: that neighborhoods are bifurcating along a white/nonwhite color line, fragmenting into homogeneous enclaves, or integrating white, black, Latino, and Asian residents into diverse residential environments. To assess hypotheses drawn from these perspectives, we develop a hybrid methodology (incorporating the entropy index and majority-rule criteria) that offers advantages over previous typological efforts. Our analysis of 1990–2000 census tract data for the 100 largest U.S. metropolitan areas finds that most neighborhoods are becoming more diverse and that members of all groups have experienced increasing exposure to neighborhood diversity. However, white populations tend to diminish rapidly in the presence of multiple minority groups and there has been concomitant white growth in low-diversity neighborhoods. Latino population dynamics have emerged as a primary force driving neighborhood change in a multi-group context. PMID:21691412

  15. Does neighborhood collective efficacy for families change over time? The Boston Neighborhood Survey

    PubMed Central

    Schmidt, Nicole M.; Tchetgen Tchetgen, Eric J.; Ehntholt, Amy; Almeida, Joanna; Nguyen, Quynh C.; Molnar, Beth E.; Azrael, Deborah; Osypuk, Theresa L.

    2014-01-01

    There is an increased interest in how neighborhood social processes, such as collective efficacy, may protect mental health. Yet little is known about how stable these neighborhood processes are over time, or how to change them to influence other downstream factors. We used a population-based, repeat cross-sectional study of adults (n=5135) to assess stability of collective efficacy for families in 38 Boston neighborhoods across 4 years (2006, 2008, 2010) (the Boston Neighborhood Survey). We test temporal stability of collective efficacy for families across and within neighborhoods using 2-level random effects linear regression, fixed effects linear regression, T-tests, and Wilcoxon rank tests. Across the different methods, neighborhood collective efficacy for families remained stable across 4 years, after adjustment for neighborhood composition. If neighborhood collective efficacy is measured within 4 years of the exposure period of interest, assuming temporal stability may be valid. PMID:24976653

  16. Does neighborhood collective efficacy for families change over time? The Boston Neighborhood Survey.

    PubMed

    Schmidt, Nicole M; Tchetgen Tchetgen, Eric J; Ehntholt, Amy; Almeida, Joanna; Nguyen, Quynh C; Molnar, Beth E; Azrael, Deborah; Osypuk, Theresa L

    2014-01-01

    There is an increased interest in how neighborhood social processes, such as collective efficacy, may protect mental health. Yet little is known about how stable these neighborhood processes are over time, or how to change them to influence other downstream factors. We used a population-based, repeat cross-sectional study of adults (n=5135) to assess stability of collective efficacy for families in 38 Boston neighborhoods across 4 years (2006, 2008, 2010) (the Boston Neighborhood Survey). We test temporal stability of collective efficacy for families across and within neighborhoods using 2-level random effects linear regression, fixed effects linear regression, T-tests, and Wilcoxon rank tests. Across the different methods, neighborhood collective efficacy for families remained stable across 4 years, after adjustment for neighborhood composition. If neighborhood collective efficacy is measured within 4 years of the exposure period of interest, assuming temporal stability may be valid. PMID:24976653

  17. Connected gene neighborhoods in prokaryotic genomes

    PubMed Central

    Rogozin, Igor B.; Makarova, Kira S.; Murvai, Janos; Czabarka, Eva; Wolf, Yuri I.; Tatusov, Roman L.; Szekely, Laszlo A.; Koonin, Eugene V.

    2002-01-01

    A computational method was developed for delineating connected gene neighborhoods in bacterial and archaeal genomes. These gene neighborhoods are not typically present, in their entirety, in any single genome, but are held together by overlapping, partially conserved gene arrays. The procedure was applied to comparing the orders of orthologous genes, which were extracted from the database of Clusters of Orthologous Groups of proteins (COGs), in 31 prokaryotic genomes and resulted in the identification of 188 clusters of gene arrays, which included 1001 of 2890 COGs. These clusters were projected onto actual genomes to produce extended neighborhoods including additional genes, which are adjacent to the genes from the clusters and are transcribed in the same direction, which resulted in a total of 2387 COGs being included in the neighborhoods. Most of the neighborhoods consist predominantly of genes united by a coherent functional theme, but also include a minority of genes without an obvious functional connection to the main theme. We hypothesize that although some of the latter genes might have unsuspected roles, others are maintained within gene arrays because of the advantage of expression at a level that is typical of the given neighborhood. We designate this phenomenon ‘genomic hitchhiking’. The largest neighborhood includes 79 genes (COGs) and consists of overlapping, rearranged ribosomal protein superoperons; apparent genome hitchhiking is particularly typical of this neighborhood and other neighborhoods that consist of genes coding for translation machinery components. Several neighborhoods involve previously undetected connections between genes, allowing new functional predictions. Gene neighborhoods appear to evolve via complex rearrangement, with different combinations of genes from a neighborhood fixed in different lineages. PMID:12000841

  18. Perceived Neighborhood Social Cohesion and Myocardial Infarction

    PubMed Central

    Kim, Eric S.; Hawes, Armani M.; Smith, Jacqui

    2015-01-01

    Background The main strategy for alleviating heart disease has been to target individuals and encourage them to change their health behaviors. Though important, emphasis on individuals has diverted focus and responsibility away from neighborhood characteristics, which also strongly influence people’s behaviors. Although a growing body of research has repeatedly demonstrated strong associations between neighborhood characteristics and cardiovascular health, it has typically focused on negative neighborhood characteristics. Only a few studies have examined the potential health enhancing effects of positive neighborhood characteristics, such as perceived neighborhood social cohesion. Methods Using multiple logistic regression models, we tested whether higher perceived neighborhood social cohesion was associated with lower incidence of myocardial infarction. Prospective data from the Health and Retirement Study—a nationally representative panel study of American adults over the age of 50—were used to analyze 5,276 participants with no history of heart disease. Respondents were tracked for four years and analyses adjusted for relevant sociodemographic, behavioral, biological, and psychosocial factors. Results In a model that adjusted for age, gender, race, marital status, education, and total wealth, each standard deviation increase in perceived neighborhood social cohesion was associated with a 22% reduced odds of myocardial infarction (OR = 0.78, 95% CI, 0.63–0.94. The association between perceived neighborhood social cohesion and myocardial infarction remained even after adjusting for behavioral, biological, and psychosocial covariates. Conclusions Higher perceived neighborhood social cohesion may have a protective effect against myocardial infarction. PMID:25135074

  19. Perceived neighborhood social cohesion and stroke.

    PubMed

    Kim, Eric S; Park, Nansook; Peterson, Christopher

    2013-11-01

    Research in the last three decades has shown that negative neighborhood factors such as neighborhood violence, noise, traffic, litter, low neighborhood socioeconomic status, and poor air quality increase the risk of poor health. Fewer studies have examined the potential protective effect that neighborhood factors can have on health, particularly stroke. We examined whether higher perceived neighborhood social cohesion was associated with lower stroke incidence after adjusting for traditional risk and psychological factors that have been linked with stroke risk. Prospective data from the Health and Retirement Study--a nationally representative panel study of American adults over the age of 50--were used. Analyses were conducted on a subset of 6740 adults who were stroke-free at baseline. Analyses adjusted for chronic illnesses and relevant sociodemographic, behavioral, and psychosocial factors. Over a four-year follow-up, higher perceived neighborhood social cohesion was associated with a lower risk of stroke. Each standard deviation increase in perceived neighborhood social cohesion was associated with a multivariate-adjusted odds ratio (O.R.) of 0.85 for stroke incidence (95% CI, 0.75-0.97, p < 0.05). The effect of perceived neighborhood social cohesion remained significant after adjusting for a comprehensive set of risk factors. Therefore, perceived neighborhood social cohesion plays an important role in protecting against stroke. PMID:24161088

  20. Portable FORTRAN contour-plotting subprogram

    SciTech Connect

    Haskell, K.H.

    1983-07-01

    In this report we discuss a contour plotting Fortran subprogram. While contour plotting subroutines are available in many commercial plotting packages, this routine has the following advantages: (1) since it uses the Weasel and VDI plot routines developed at Sandia, it occupies little storage and can be used on most of the Sandia time-sharing systems as part of a larger program. In the past, the size of plotting packages often forced a user to perform plotting operations in a completely separate program; (2) the contour computation algorithm is efficient and robust, and computes accurate contours for sets of data with low resolution; and (3) the subprogram is easy to use. A simple contour plot can be produced with a minimum of information provided by a user in one Fortran subroutine call. Through the use of a wide variety of subroutine options, many additional features can be used. These include such items as plot titles, grid lines, placement of text on the page, etc. The subroutine is written in portable Fortran 77, and is designed to run on any system which supports the Weasel and VDI plot packages. It also uses routines from the SLATEC mathematical subroutine library.

  1. Prostate Contouring Variation: Can It Be Fixed?

    SciTech Connect

    Khoo, Eric L.H.; Schick, Karlissa; Plank, Ashley W.; Poulsen, Michael; Wong, Winnie W.G.; Middleton, Mark; Martin, Jarad M.

    2012-04-01

    Purpose: To assess whether an education program on CT and MRI prostate anatomy would reduce inter- and intraobserver prostate contouring variation among experienced radiation oncologists. Methods and Materials: Three patient CT and MRI datasets were selected. Five radiation oncologists contoured the prostate for each patient on CT first, then MRI, and again between 2 and 4 weeks later. Three education sessions were then conducted. The same contouring process was then repeated with the same datasets and oncologists. The observer variation was assessed according to changes in the ratio of the encompassing volume to intersecting volume (volume ratio [VR]), across sets of target volumes. Results: For interobserver variation, there was a 15% reduction in mean VR with CT, from 2.74 to 2.33, and a 40% reduction in mean VR with MRI, from 2.38 to 1.41 after education. A similar trend was found for intraobserver variation, with a mean VR reduction for CT and MRI of 9% (from 1.51 to 1.38) and 16% (from 1.37 to 1.15), respectively. Conclusion: A well-structured education program has reduced both inter- and intraobserver prostate contouring variations. The impact was greater on MRI than on CT. With the ongoing incorporation of new technologies into routine practice, education programs for target contouring should be incorporated as part of the continuing medical education of radiation oncologists.

  2. Validation of bone segmentation and improved 3-D registration using contour coherency in CT data.

    PubMed

    Wang, Liping Ingrid; Greenspan, Michael; Ellis, Randy

    2006-03-01

    A method is presented to validate the segmentation of computed tomography (CT) image sequences, and improve the accuracy and efficiency of the subsequent registration of the three-dimensional surfaces that are reconstructed from the segmented slices. The method compares the shapes of contours extracted from neighborhoods of slices in CT stacks of tibias. The bone is first segmented by an automatic segmentation technique, and the bone contour for each slice is parameterized as a one-dimensional function of normalized arc length versus inscribed angle. These functions are represented as vectors within a K-dimensional space comprising the first K amplitude coefficients of their Fourier Descriptors. The similarity or coherency of neighboring contours is measured by comparing statistical properties of their vector representations within this space. Experimentation has demonstrated this technique to be very effective at identifying low-coherency segmentations. Compared with experienced human operators, in a set of 23 CT stacks (1,633 slices), the method correctly detected 87.5% and 80% of the low-coherency and 97.7% and 95.5% of the high coherency segmentations, respectively from two different automatic segmentation techniques. Removal of the automatically detected low-coherency segmentations also significantly improved the accuracy and time efficiency of the registration of 3-D bone surface models. The registration error was reduced by over 500% (i.e., a factor of 5) and 280%, and the computational performance was improved by 540% and 791% for the two respective segmentation methods. PMID:16524088

  3. Neighborhoods and Youth: How Neighborhood Demographics and Social Processes Affect Youth Outcomes

    ERIC Educational Resources Information Center

    Swisher, Ray

    2008-01-01

    Researchers over the past two decades have increasingly recognized the importance of neighborhood contexts for youth development. For example, living in a disadvantaged neighborhood has been associated with a wide range of negative outcomes throughout the early years of the life course. However, neighborhoods likely have very different effects,…

  4. Neighborhood-Level Factors and Youth Violence: Giving Voice to the Perceptions of Prominent Neighborhood Individuals

    ERIC Educational Resources Information Center

    Yonas, Michael A.; O'Campo, Patricia; Burke, Jessica G.; Gielen, Andrea C.

    2007-01-01

    Youth violence is a significant public health problem. Although the relationship between neighborhood-level factors and urban youth violence is recognized, the specific mechanisms of this relationship are often unclear. Prominent neighborhood individuals were identified within four select low-income urban neighborhoods in Baltimore City. In-depth…

  5. Neighborhood-Specific and General Social Support: Which Buffers the Effect of Neighborhood Disorder on Depression?

    ERIC Educational Resources Information Center

    Kim, Joongbaeck; Ross, Catherine E.

    2009-01-01

    Is neighborhood-specific social support the most effective type of social support for buffering the effect of neighborhood disorder on depression? Matching theory suggests that it is. The authors extend the research on neighborhood disorder and adult depression by showing that individuals who have higher levels of both general and…

  6. How big is my neighborhood? Individual and contextual effects on perceptions of neighborhood scale.

    PubMed

    Coulton, Claudia J; Jennings, M Zane; Chan, Tsui

    2013-03-01

    Neighborhood is a social and geographic concept that plays an increasingly important role in research and practice that address disparities in health and well-being of populations. However, most studies of neighborhoods, as well as community initiatives geared toward neighborhood improvement, make simplifying assumptions about boundaries, often relying on census geography to operationalize the neighborhood units. This study used geographic information system (GIS) tools to gather and analyze neighborhood maps drawn by residents of low-income communities in 10 cities. The median resident map size was approximately 30 percent smaller than the median census tract, but 25 percent of residents viewed their neighborhood as quite small (less than one-fifth of the typical census tract). Multi-level modeling showed significant within context variation in perceived neighborhood scale. Longer term residents with higher education and income and who were more engaged in the neighborhood held more expansive views. But there were also contextual influences with higher density and mixed use areas associated with smaller perceived neighborhoods, and higher collective efficacy associated with larger neighborhood sizes. Artificially imposed neighborhood units may misrepresent resident experience, but GIS tools can be used to craft more authentic neighborhood definitions for research and practice. PMID:22886284

  7. Coding Long Contour Shapes of Binary Objects

    NASA Astrophysics Data System (ADS)

    Sánchez-Cruz, Hermilo; Rodríguez-Díaz, Mario A.

    This is an extension of the paper appeared in [15]. This time, we compare four methods: Arithmetic coding applied to 3OT chain code (Arith-3OT), Arithmetic coding applied to DFCCE (Arith-DFCCE), Huffman coding applied to DFCCE chain code (Huff-DFCCE), and, to measure the efficiency of the chain codes, we propose to compare the methods with JBIG, which constitutes an international standard. In the aim to look for a suitable and better representation of contour shapes, our probes suggest that a sound method to represent contour shapes is 3OT, because Arithmetic coding applied to it gives the best results regarding JBIG, independently of the perimeter of the contour shapes.

  8. Modified contour-improved perturbation theory

    SciTech Connect

    Cvetic, Gorazd; Loewe, Marcelo; Martinez, Cristian; Valenzuela, Cristian

    2010-11-01

    The semihadronic tau decay width allows a clean extraction of the strong coupling constant at low energies. We present a modification of the standard ''contour-improved'' method based on a derivative expansion of the Adler function. The new approach has some advantages compared to contour-improved perturbation theory. The renormalization scale dependence is weaker by more than a factor of 2 and the last term of the expansion is reduced by about 10%, while the renormalization scheme dependence remains approximately equal. The extracted QCD coupling at the tau mass scale is by 2% lower than the contour-improved value. We find {alpha}{sub s}(M{sub Z}{sup 2})=0.1211{+-}0.0010.

  9. Marriage and parenthood in relation to obesogenic neighborhood trajectories: The CARDIA Study

    PubMed Central

    Boone-Heinonen, Janne; Howard, Annie Green; Meyer, Katie; Lewis, Cora E.; Kiefe, Catarina I.; Laroche, Helena H.; Gunderson, Erica P.; Gordon-Larsen, Penny

    2015-01-01

    Marriage and parenthood are associated with weight gain and residential mobility. Little is known about how obesity-relevant environmental contexts differ according to family structure. We estimated trajectories of neighborhood poverty, population density, and density of fast food restaurants, supermarkets, and commercial and public physical activity facilities for adults from a biracial cohort (CARDIA, n=4,174, aged 25–50) over 13 years (1992–93 through 2005–06) using latent growth curve analysis. We estimated associations of marriage, parenthood, and race with the observed neighborhood trajectories. Married participants tended to live in neighborhoods with lower poverty, population density, and availability of all types of food and physical activity amenities. Parenthood was similarly but less consistently related to neighborhood characteristics. Marriage and parenthood were more strongly related to neighborhood trajectories in whites (versus blacks), who, in prior studies, exhibit weaker associations between neighborhood characteristics and health. Greater understanding of how interactive family and neighborhood environments contribute to healthy living is needed. PMID:26093081

  10. Marriage and parenthood in relation to obesogenic neighborhood trajectories: The CARDIA study.

    PubMed

    Boone-Heinonen, Janne; Howard, Annie Green; Meyer, Katie; Lewis, Cora E; Kiefe, Catarina I; Laroche, Helena H; Gunderson, Erica P; Gordon-Larsen, Penny

    2015-07-01

    Marriage and parenthood are associated with weight gain and residential mobility. Little is known about how obesity-relevant environmental contexts differ according to family structure. We estimated trajectories of neighborhood poverty, population density, and density of fast food restaurants, supermarkets, and commercial and public physical activity facilities for adults from a biracial cohort (CARDIA, n=4,174, aged 25-50) over 13 years (1992-93 through 2005-06) using latent growth curve analysis. We estimated associations of marriage, parenthood, and race with the observed neighborhood trajectories. Married participants tended to live in neighborhoods with lower poverty, population density, and availability of all types of food and physical activity amenities. Parenthood was similarly but less consistently related to neighborhood characteristics. Marriage and parenthood were more strongly related to neighborhood trajectories in whites (versus blacks), who, in prior studies, exhibit weaker associations between neighborhood characteristics and health. Greater understanding of how interactive family and neighborhood environments contribute to healthy living is needed. PMID:26093081

  11. Urban Poverty and Neighborhood Effects on Crime: Incorporating Spatial and Network Perspectives

    PubMed Central

    Graif, Corina; Gladfelter, Andrew S.; Matthews, Stephen A.

    2015-01-01

    Research on neighborhoods and crime is on a remarkable growth trajectory. In this article, we survey important recent developments in the scholarship on neighborhood effects and the spatial stratification of poverty and urban crime. We advance the case that, in understanding the impact of neighborhoods and poverty on crime, sociological and criminological research would benefit from expanding the analytical focus from residential neighborhoods to the network of neighborhoods individuals are exposed to during their daily routine activities. This perspective is supported by reemerging scholarship on activity spaces and macro-level research on inter-neighborhood connections. We highlight work indicating that non-residential contexts add variation in criminogenic exposure, which in turn influence offending behavior and victimization risk. Also, we draw on recent insights from research on gang violence, social and institutional connections, and spatial mismatch, and call for advancements in the scholarship on urban poverty that investigates the salience of inter-neighborhood connections in evaluating the spatial stratification of criminogenic risk for individuals and communities. PMID:27375773

  12. Star formation rate in the solar neighborhood

    NASA Astrophysics Data System (ADS)

    Cignoni, Michele

    2006-08-01

    This thesis develops a method for obtaining the star formation histories of a mixed, resolved population through the use of color-magnitude diagrams (CMDs). The method is applied to the derivation of the local star formation rate, modeling observations of the Hipparcos satellite wigth synthetic CMDs computed for different star formation histories with an updated stellar evolution library. Parallax and photometric uncertainties are included explicitly and corrected using the Bayesian Richardson-Lucy algorithm. We find that the solar neighborhood star formation rate has a characteristic timescale for variation of about 6 Gyr, with a maximum activity close to 3 Gyr ago. This suggests a global, rather than local, star forming event. The summary and conclusions are included here, the full thesis is available at the URL listed above.

  13. Measuring walking within and outside the neighborhood in Chinese elders: reliability and validity

    PubMed Central

    2011-01-01

    Background Walking is a preferred, prevalent and recommended activity for aging populations and is influenced by the neighborhood built environment. To study this influence it is necessary to differentiate whether walking occurs within or outside of the neighborhood. The Neighborhood Physical Activity Questionnaire (NPAQ) collects information on setting-specific physical activity, including walking, inside and outside one's neighborhood. While the NPAQ has shown to be a reliable measure in adults, its reliability in older adults is unknown. Additionally its validity and the influence of type of neighborhood on reliability and validity have yet to be explored. Methods The NPAQ walking component was adapted for Chinese speaking elders (NWQ-CS). Ninety-six Chinese elders, stratified by social economic status and neighborhood walkability, wore an accelerometer and completed a log of walks for 7 days. Following the collection of valid data the NWQ-CS was interviewer-administered. Fourteen to 20 days (average of 17 days) later the NWQ-CS was re-administered. Test-retest reliability and validity of the NWQ-CS were assessed. Results Reliability and validity estimates did not differ with type of neighborhood. NWQ-CS measures of walking showed moderate to excellent reliability. Reliability was generally higher for estimates of weekly frequency than minutes of walking. Total weekly minutes of walking were moderately related to all accelerometry measures. Moderate-to-strong associations were found between the NWQ-CS and log-of-walks variables. The NWQ-CS yielded statistically significantly lower mean values of total walking, weekly minutes of walking for transportation and weekly frequency of walking for transportation outside the neighborhood than the log-of-walks. Conclusions The NWQ-CS showed measurement invariance across types of neighborhoods. It is a valid measure of walking for recreation and frequency of walking for transport. However, it may systematically

  14. Neighborhood Social Capital, Neighborhood Attachment, and Dental Care Use for Los Angeles Family and Neighborhood Survey Adults

    PubMed Central

    Carpiano, Richard M.

    2013-01-01

    Objectives. We tested the hypothesis that neighborhood-level social capital and individual-level neighborhood attachment are positively associated with adult dental care use. Methods. We analyzed data from the 2000–2001 Los Angeles Family and Neighborhood Survey that were linked to US Census Bureau data from 2000 (n = 1800 adults aged 18–64 years across 65 neighborhoods). We used 2-level hierarchical logistic regression models to estimate the odds of dental use associated with each of 4 forms of social capital and neighborhood attachment. Results. After adjusting for confounders, the odds of dental use were significantly associated with only 1 form of social capital: social support (adjusted odds ratio [AOR] = 0.85; 95% confidence interval [CI] = 0.72, 0.99). Individual-level neighborhood attachment was positively associated with dental care use (AOR = 1.05; 95% CI = 1.01, 1.10). Conclusions. Contrary to our hypothesis, adults in neighborhoods with higher levels of social capital, particularly social support, were significantly less likely to use dental care. Future research should identify the oral health–related attitudes, beliefs, norms, and practices in neighborhoods and other behavioral and cultural factors that moderate and mediate the relationship between social capital and dental care use. PMID:23409881

  15. Contour-based classification of video objects

    NASA Astrophysics Data System (ADS)

    Richter, Stephan; Kuehne, Gerald; Schuster, Oliver

    2000-12-01

    The recognition of objects that appear in a video sequence is an essential aspect of any video content analysis system. We present an approach which classifies a segmented video object base don its appearance in successive video frames. The classification is performed by matching curvature features of the contours of these object views to a database containing preprocessed views of prototypical objects using a modified curvature scale space technique. By integrating the result of an umber of successive frames and by using the modified curvature scale space technique as an efficient representation of object contours, our approach enables the robust, tolerant and rapid object classification of video objects.

  16. Contour-based classification of video objects

    NASA Astrophysics Data System (ADS)

    Richter, Stephan; Kuehne, Gerald; Schuster, Oliver

    2001-01-01

    The recognition of objects that appear in a video sequence is an essential aspect of any video content analysis system. We present an approach which classifies a segmented video object base don its appearance in successive video frames. The classification is performed by matching curvature features of the contours of these object views to a database containing preprocessed views of prototypical objects using a modified curvature scale space technique. By integrating the result of an umber of successive frames and by using the modified curvature scale space technique as an efficient representation of object contours, our approach enables the robust, tolerant and rapid object classification of video objects.

  17. Leaf Shape Recognition using Centroid Contour Distance

    NASA Astrophysics Data System (ADS)

    Hasim, Abdurrasyid; Herdiyeni, Yeni; Douady, Stephane

    2016-01-01

    This research recognizes the leaf shape using Centroid Contour Distance (CCD) as shape descriptor. CCD is an algorithm of shape representation contour-based approach which only exploits boundary information. CCD calculates the distance between the midpoint and the points on the edge corresponding to interval angle. Leaf shapes that included in this study are ellips, cordate, ovate, and lanceolate. We analyzed 200 leaf images of tropical plant. Each class consists of 50 images. The best accuracy is obtained by 96.67%. We used Probabilistic Neural Network to classify the leaf shape. Experimental results demonstrated the effectiveness of the proposed approach for shape recognition with high accuracy.

  18. The velocity snake: Deformable contour for tracking in spatio-velocity space

    SciTech Connect

    Peterfreund, N.

    1997-06-01

    The author presents a new active contour model for boundary tracking and position prediction of nonrigid objects, which results from applying a velocity control to the class of elastodynamical contour models, known as snakes. The proposed control term minimizes an energy dissipation function which measures the difference between the contour velocity and the apparent velocity of the image. Treating the image video-sequence as continuous measurements along time, it is shown that the proposed control results in an unbiased tracking. This is in contrast to the original snake model which is proven to be biased due to the image (object) velocity, thus resulting in high sensitivity to image clutter. The motion estimation further allows for position prediction of nonrigid boundaries. Based on the proposed control approach, the author proposes a new class of real time tracking contours, varying from models with batch-mode control estimation to models with real time adaptive controllers.

  19. Do observed or perceived characteristics of the neighborhood environment mediate associations between neighborhood poverty and cumulative biological risk?

    PubMed Central

    Schulz, Amy J.; Mentz, Graciela; Lachance, Laurie; Zenk, Shannon N.; Johnson, Jonetta; Stokes, Carmen; Mandell, Rebecca

    2013-01-01

    Objective To examine contributions of observed and perceived neighborhood characteristics in explaining associations between neighborhood poverty and cumulative biological risk (CBR) in an urban community. Methods Multilevel regression analyses were conducted using cross-sectional data from a probability sample survey (n=919), and observational and census data. Dependent variable: CBR. Independent variables: Neighborhood disorder, deterioration and characteristics; perceived neighborhood social environment, physical environment, and neighborhood environment. Covariates: Neighborhood and individual demographics, health-related behaviors. Results Observed and perceived indicators of neighborhood conditions were significantly associated with CBR, after accounting for both neighborhood and individual level socioeconomic indicators. Observed and perceived neighborhood environmental conditions mediated associations between neighborhood poverty and CBR. Conclusions Findings were consistent with the hypothesis that neighborhood conditions associated with economic divestment mediate associations between neighborhood poverty and CBR. PMID:24100238

  20. Better Buildings Neighborhood Program Progress Stories

    SciTech Connect

    2012-04-19

    n neighborhoods across the country, stories are emerging constantly of individuals, businesses, and organizations that are benefiting from energy efficiency. Included are the stories of real people making their homes, businesses, and communities better with the help of the Better Buildings Neighborhood Program.

  1. Neighborhood Bridges: A Subversive Act of Storytelling

    ERIC Educational Resources Information Center

    DeMark, Sharon

    2004-01-01

    In this article, the author describes Neighborhood Bridges, The Children's Theatre Company's (CTC) critical literacy program that gives young people from the most impoverished and troubled neighborhoods in Minneapolis the courage and power to speak their minds both orally and through the written word in such a daunting setting. The 2003-04 school…

  2. Essays on Neighborhood Transition and Housing Markets

    ERIC Educational Resources Information Center

    Casey, Marcus D.

    2009-01-01

    This dissertation presents new evidence on neighborhood transition and its impact on housing markets using a novel micro-level dataset on housing transactions. It focuses on three issues: the neighborhood effect, housing discrimination, and stable integration. The first essay examines the relationship between increased minority composition and…

  3. Community Gardening, Neighborhood Meetings, and Social Capital

    ERIC Educational Resources Information Center

    Alaimo, Katherine; Reischl, Thomas M.; Allen, Julie Ober

    2010-01-01

    This study examined associations between participation in community gardening/beautification projects and neighborhood meetings with perceptions of social capital at both the individual and neighborhood levels. Data were analyzed from a cross-sectional stratified random telephone survey conducted in Flint, Michigan (N=1916). Hierarchical linear…

  4. Perceived Neighborhood Safety and Adolescent School Functioning

    ERIC Educational Resources Information Center

    Martin-Storey, Alexa; Crosnoe, Robert

    2014-01-01

    This study examined the association between adolescents' perceptions of their neighborhoods' safety and multiple elements of their functioning in school with data on 15 year olds from the NICHD Study of Early Child Care and Youth Development (n = 924). In general, perceived neighborhood safety was more strongly associated with aspects of…

  5. Training Neighborhood Residents to Conduct a Survey

    ERIC Educational Resources Information Center

    Back, Susan Malone; Tseng, Wan-Chun; Li, Jiaqi; Wang, Yuanhua; Phan, Van Thanh; Yeter, Ibrahim Halil

    2015-01-01

    As a requirement for a federal neighborhood revitalization grant, the authors trained resident interviewers and coordinated the conduct of more than 1000 door-to-door interviews of a stratified random sample. The targeted area was a multiethnic, lower income neighborhood that continues to experience the effects of past segregation. Monitoring and…

  6. Neighborhood Transition and Mental Hospitalization Patterns.

    ERIC Educational Resources Information Center

    Muhlin, Gregory L.

    1979-01-01

    Assesses the relationship of change in neighborhood ethnic composition and 1970 psychiatric hospitalization rates for persons born in Ireland, Germany, Poland, Austria, Hungary, the U.S.S.R., and Italy. Concludes that such neighborhood change was unrelated to psychiatric hospitalization rates of the foreign born. Discusses policy implications and…

  7. Who Moves to Mixed-Income Neighborhoods?*

    PubMed Central

    McKinnish, Terra; White, T. Kirk

    2011-01-01

    This paper uses confidential Census data, specifically the 1990 and 2000 Census Long Form data, to study the income dispersion of recent cohorts of migrants to mixed-income neighborhoods. We investigate whether neighborhoods with high levels of income dispersion attract economically diverse in-migrants. If recent in-migrants to mixed-income neighborhoods exhibit high levels of income dispersion, this is consistent with stable mixed-income neighborhoods. If, however, mixed-income neighborhoods are comprised of homogenous low-income (high-income) cohorts of long-term residents combined with homogenous high-income (low-income) cohorts of recent arrivals, this is consistent with neighborhood transition. Our results indicate that neighborhoods with high levels of income dispersion do in fact attract a much more heterogeneous set of in-migrants, particularly from the tails of the income distribution. Our results also suggest that the residents of mixed-income neighborhoods may be less heterogeneous with respect to lifetime income. PMID:21479114

  8. Neighborhood Organizing for Urban School Reform.

    ERIC Educational Resources Information Center

    Williams, Michael R.

    This book analyzes how community-based organizations in low income urban neighborhoods can promote reform of their local public schools. Chapter 1, "Reassessing the Declining Urban Neighborhood," discusses the sources of urban decline in terms of a structural relationship between "haves" and "have-nots." Chapter 2, "Reassessing Victimhood,"…

  9. Individual, family, and neighborhood correlates of independent mobility among 7 to 11-year-olds.

    PubMed

    Janssen, Ian; Ferrao, Thomas; King, Nathan

    2016-06-01

    Objective. Independent mobility refers to the freedom that children have to move around their neighborhood without adult supervision. It is related to their physical activity and health. We examined the intrapersonal, family, and neighborhood correlates of independent mobility within children. Methods. 497 American parents of 6.9-11.9 year olds completed a survey (November, 2014) that assessed their child's independent mobility range, several intrapersonal characteristics of their child (gender, age, race, etc.), several characteristics of their family (family structure, socioeconomic status, parental physical activity, etc.), and their perceptions of the safety of their neighborhood (18 questions reduced to 4 components). Associations were determined using ordinal logistic regression. Results. Children's age, parent's perception that their neighborhood is safe for children, and parent's fear of neighborhood crime were the independent correlates of independent mobility. Compared to 6.9-7.9 year olds, the odds ratio (95% CI) for increasing independent mobility were 2.31 (1.47-3.64) in 8.0-9.9 year olds and 3.38 (2.13-5.36) in 10.0-11.9 year olds. Compared to children whose parents who did not perceive that their neighborhood was safe for children, the odds ratio for increasing independent mobility was 4.24 (2.68-6.70) for children whose parents perceived their neighborhood was safe for children. Compared to children whose parents had the lowest fear of neighborhood crime, the odds ratio for increasing independent mobility was 0.41 (0.27-0.62) for children whose parents had the highest fear of crime. Conclusions. Children's independent mobility was associated with their age, their parent's perception that their neighborhood was safe for children, and their parent's fear of crime. PMID:26844195

  10. Individual, family, and neighborhood correlates of independent mobility among 7 to 11-year-olds

    PubMed Central

    Janssen, Ian; Ferrao, Thomas; King, Nathan

    2015-01-01

    Objective. Independent mobility refers to the freedom that children have to move around their neighborhood without adult supervision. It is related to their physical activity and health. We examined the intrapersonal, family, and neighborhood correlates of independent mobility within children. Methods. 497 American parents of 6.9–11.9 year olds completed a survey (November, 2014) that assessed their child's independent mobility range, several intrapersonal characteristics of their child (gender, age, race, etc.), several characteristics of their family (family structure, socioeconomic status, parental physical activity, etc.), and their perceptions of the safety of their neighborhood (18 questions reduced to 4 components). Associations were determined using ordinal logistic regression. Results. Children's age, parent's perception that their neighborhood is safe for children, and parent's fear of neighborhood crime were the independent correlates of independent mobility. Compared to 6.9–7.9 year olds, the odds ratio (95% CI) for increasing independent mobility were 2.31 (1.47–3.64) in 8.0–9.9 year olds and 3.38 (2.13–5.36) in 10.0–11.9 year olds. Compared to children whose parents who did not perceive that their neighborhood was safe for children, the odds ratio for increasing independent mobility was 4.24 (2.68–6.70) for children whose parents perceived their neighborhood was safe for children. Compared to children whose parents had the lowest fear of neighborhood crime, the odds ratio for increasing independent mobility was 0.41 (0.27–0.62) for children whose parents had the highest fear of crime. Conclusions. Children's independent mobility was associated with their age, their parent's perception that their neighborhood was safe for children, and their parent's fear of crime. PMID:26844195

  11. Contour junctions underlie neural representations of scene categories in high-level human visual cortex.

    PubMed

    Choo, Heeyoung; Walther, Dirk B

    2016-07-15

    Humans efficiently grasp complex visual environments, making highly consistent judgments of entry-level category despite their high variability in visual appearance. How does the human brain arrive at the invariant neural representations underlying categorization of real-world environments? We here show that the neural representation of visual environments in scene-selective human visual cortex relies on statistics of contour junctions, which provide cues for the three-dimensional arrangement of surfaces in a scene. We manipulated line drawings of real-world environments such that statistics of contour orientations or junctions were disrupted. Manipulated and intact line drawings were presented to participants in an fMRI experiment. Scene categories were decoded from neural activity patterns in the parahippocampal place area (PPA), the occipital place area (OPA) and other visual brain regions. Disruption of junctions but not orientations led to a drastic decrease in decoding accuracy in the PPA and OPA, indicating the reliance of these areas on intact junction statistics. Accuracy of decoding from early visual cortex, on the other hand, was unaffected by either image manipulation. We further show that the correlation of error patterns between decoding from the scene-selective brain areas and behavioral experiments is contingent on intact contour junctions. Finally, a searchlight analysis exposes the reliance of visually active brain regions on different sets of contour properties. Statistics of contour length and curvature dominate neural representations of scene categories in early visual areas and contour junctions in high-level scene-selective brain regions. PMID:27118087

  12. Using Modified Contour Deformable Model to Quantitatively Estimate Ultrasound Parameters for Osteoporosis Assessment

    NASA Astrophysics Data System (ADS)

    Chen, Yung-Fu; Du, Yi-Chun; Tsai, Yi-Ting; Chen, Tainsong

    Osteoporosis is a systemic skeletal disease, which is characterized by low bone mass and micro-architectural deterioration of bone tissue, leading to bone fragility. Finding an effective method for prevention and early diagnosis of the disease is very important. Several parameters, including broadband ultrasound attenuation (BUA), speed of sound (SOS), and stiffness index (STI), have been used to measure the characteristics of bone tissues. In this paper, we proposed a method, namely modified contour deformable model (MCDM), bases on the active contour model (ACM) and active shape model (ASM) for automatically detecting the calcaneus contour from quantitative ultrasound (QUS) parametric images. The results show that the difference between the contours detected by the MCDM and the true boundary for the phantom is less than one pixel. By comparing the phantom ROIs, significant relationship was found between contour mean and bone mineral density (BMD) with R=0.99. The influence of selecting different ROI diameters (12, 14, 16 and 18 mm) and different region-selecting methods, including fixed region (ROI fix ), automatic circular region (ROI cir ) and calcaneal contour region (ROI anat ), were evaluated for testing human subjects. Measurements with large ROI diameters, especially using fixed region, result in high position errors (10-45%). The precision errors of the measured ultrasonic parameters for ROI anat are smaller than ROI fix and ROI cir . In conclusion, ROI anat provides more accurate measurement of ultrasonic parameters for the evaluation of osteoporosis and is useful for clinical application.

  13. Who Gentrifies Low-Income Neighborhoods?*

    PubMed Central

    McKinnish, Terra; Walsh, Randall; White, T. Kirk

    2009-01-01

    This paper uses confidential Census data, specifically the 1990 and 2000 Census Long Form data, to study demographic processes in neighborhoods that gentrified during the 1990’s. In contrast to previous studies, the analysis is conducted at the more refined census-tract level, with a narrower definition of gentrification and more closely matched comparison neighborhoods. Furthermore, our access to individual-level data with census tract identifiers allows us to separately identify recent in-migrants and long-term residents. Our results indicate that, on average, the demographic flows associated with the gentrification of urban neighborhoods during the 1990’s are not consistent with displacement and harm to minority households. In fact, taken as a whole, our results suggest that gentrification of predominantly black neighborhoods creates neighborhoods that are attractive to middle-class black households. PMID:20161532

  14. Who Gentrifies Low-Income Neighborhoods?

    PubMed

    McKinnish, Terra; Walsh, Randall; White, T Kirk

    2010-03-01

    This paper uses confidential Census data, specifically the 1990 and 2000 Census Long Form data, to study demographic processes in neighborhoods that gentrified during the 1990's. In contrast to previous studies, the analysis is conducted at the more refined census-tract level, with a narrower definition of gentrification and more closely matched comparison neighborhoods. Furthermore, our access to individual-level data with census tract identifiers allows us to separately identify recent in-migrants and long-term residents. Our results indicate that, on average, the demographic flows associated with the gentrification of urban neighborhoods during the 1990's are not consistent with displacement and harm to minority households. In fact, taken as a whole, our results suggest that gentrification of predominantly black neighborhoods creates neighborhoods that are attractive to middle-class black households. PMID:20161532

  15. Neighborhood Racial Isolation, Disorder and Obesity

    PubMed Central

    Chang, Virginia W.; Hillier, Amy E.; Mehta, Neil K.

    2010-01-01

    Recent research suggests that racial residential segregation may be detrimental to health. This study investigates the influence of neighborhood racial isolation on obesity and considers the role of neighborhood disorder as a mediator in this relationship. For the city of Philadelphia, we find that residence in a neighborhood with high black racial isolation is associated with a higher body mass index and higher odds of obesity among women, but not men, highlighting important sex differences in the influence of neighborhood structure on health. Furthermore, the influence of high racial isolation on women’s weight status is mediated, in part, by the physically disordered nature of such neighborhoods. Disorder of a more social nature (as measured by incident crime) is not associated with weight status. PMID:20179775

  16. Apparatus for electrolytically tapered or contoured cavities

    NASA Technical Reports Server (NTRS)

    Williams, L. A. (Inventor)

    1967-01-01

    An electrolytic machining apparatus for forming tapered or contoured cavities in an electrically conductive and electrochemically erodible piece is presented. It supports the workpiece and an electrode for movement relatively toward each other and has means for pumping an electrolyte between the workpiece and the electrode.

  17. Improved discrimination in photographic density contouring

    NASA Technical Reports Server (NTRS)

    Godding, R. A.

    1974-01-01

    Density discrimination can be accomplished through use of special photographic contouring material which has two sensitive layers (one negative, one positive) on single support. Process will be of interest to investigators who require finer discrimination of densities of original photograph for purposes such as identification of crops and analysis of energy levels of radiating objects.

  18. Automatic Contour Tracking in Ultrasound Images

    ERIC Educational Resources Information Center

    Li, Min; Kambhamettu, Chandra; Stone, Maureen

    2005-01-01

    In this paper, a new automatic contour tracking system, EdgeTrak, for the ultrasound image sequences of human tongue is presented. The images are produced by a head and transducer support system (HATS). The noise and unrelated high-contrast edges in ultrasound images make it very difficult to automatically detect the correct tongue surfaces. In…

  19. Expectations for Melodic Contours Transcend Pitch

    PubMed Central

    Graves, Jackson E.; Micheyl, Christophe; Oxenham, Andrew J.

    2015-01-01

    The question of what makes a good melody has interested composers, music theorists, and psychologists alike. Many of the observed principles of good “melodic continuation” involve melodic contour – the pattern of rising and falling pitch within a sequence. Previous work has shown that contour perception can extend beyond pitch to other auditory dimensions, such as brightness and loudness. Here, we show with two experiments that the generalization of contour perception to non-traditional dimensions also extends to melodic expectations. In the first experiment, subjective ratings for three-tone sequences that vary in brightness or loudness conformed to the same general contour-based expectations as pitch sequences. In the second experiment, we modified the sequence of melody presentation such that melodies with the same beginning were blocked together. This change produced substantively different results, but the patterns of ratings remained similar across the three auditory dimensions. Taken together, these results suggest that 1) certain well-known principles of melodic expectation (such as the expectation for a reversal following a skip) are dependent on long-term context, and 2) these expectations are not unique to the dimension of pitch and may instead reflect more general principles of perceptual organization. PMID:25365571

  20. Expectations for melodic contours transcend pitch.

    PubMed

    Graves, Jackson E; Micheyl, Christophe; Oxenham, Andrew J

    2014-12-01

    The question of what makes a good melody has interested composers, music theorists, and psychologists alike. Many of the observed principles of good "melodic continuation" involve melodic contour-the pattern of rising and falling pitch within a sequence. Previous work has shown that contour perception can extend beyond pitch to other auditory dimensions, such as brightness and loudness. Here, we show that the generalization of contour perception to nontraditional dimensions also extends to melodic expectations. In the first experiment, subjective ratings for 3-tone sequences that vary in brightness or loudness conformed to the same general contour-based expectations as pitch sequences. In the second experiment, we modified the sequence of melody presentation such that melodies with the same beginning were blocked together. This change produced substantively different results, but the patterns of ratings remained similar across the 3 auditory dimensions. Taken together, these results suggest that (a) certain well-known principles of melodic expectation (such as the expectation for a reversal following a skip) are dependent on long-term context, and (b) these expectations are not unique to the dimension of pitch and may instead reflect more general principles of perceptual organization. PMID:25365571

  1. Contoured Orifice for Silicon-Ribbon Die

    NASA Technical Reports Server (NTRS)

    Mackintosh, B. H.

    1985-01-01

    Die configuration encourages purity and stable growth. Contour of die orifice changes near ribbon edges. As result, silicon ribbon has nearly constant width and little carbon contamination. Die part of furnace being developed to produce high-quality, low-cost material for solar cells.

  2. A Computer Language for ECG Contour Analysis

    PubMed Central

    McConnochie, John W.

    1982-01-01

    The purpose of this paper is to demonstrate contructively that criteria for ECG contour analysis can be interpreted directly by a computer. Thereby, the programming task is greatly reduced. Direct interpretation is achieved by the creation of a computer language that is well-suited for the expression of such criteria. Further development of the language is planned.

  3. Contour completion through depth interferes with stereoacuity

    NASA Technical Reports Server (NTRS)

    Vreven, Dawn; McKee, Suzanne P.; Verghese, Preeti

    2002-01-01

    Local disparity signals must interact in visual cortex to represent boundaries and surfaces of three-dimensional (3D) objects. We investigated how disparity signals interact in 3D contours and in 3D surfaces generated from the contours. We compared flat (single disparity) stimuli with curved (multi-disparity) stimuli. We found no consistent differences in sensitivity to contours vs. surfaces; for equivalent amounts of disparity, however, observers were more sensitive to flat stimuli than curved stimuli. Poor depth sensitivity for curved stimuli cannot be explained by the larger range of disparities present in the curved surface, nor by disparity averaging, nor by poor sensitivity to the largest disparity in the stimulus. Surprisingly, sensitivity to surfaces curved in depth was improved by removing portions of the surface and thus removing disparity information. Stimulus configuration had a profound effect on stereo thresholds that cannot be accounted for by disparity-energy models of V1 processing. We suggest that higher-level 3D contour or 3D shape mechanisms are involved.

  4. Molding Compound For Inspection Of Internal Contours

    NASA Technical Reports Server (NTRS)

    Adams, Jim; Ricklefs, Steve

    1988-01-01

    Material clean, sets rapidly, and easy to use. Silicone elastomer, Citrocon or equivalent, commonly used in dentistry, in combination with mold-release agent (Also see MFS-29240), speeds and facilitates making of impressions of interior surfaces so surface contours examined. Elastomer easily moved around in cavity until required location found.

  5. Aircraft noise source and contour estimation

    NASA Technical Reports Server (NTRS)

    Dunn, D. G.; Peart, N. A.

    1973-01-01

    Calculation procedures are presented for predicting the noise-time histories and noise contours (footprints) of five basic types of aircraft; turbojet, turofan, turboprop, V/STOL, and helicopter. The procedures have been computerized to facilitate prediction of the noise characteristics during takeoffs, flyovers, and/or landing operations.

  6. Contour-measuring tool for composite layups

    NASA Technical Reports Server (NTRS)

    Fontes, M. J.

    1981-01-01

    Simple handtool helps form contours and complex shapes from laminae of resin-impregnated fabric. Tool, which consists of yoke having ballpoint pen and spindle and gage, is placed so that it straddles model. As toll is moved, pen draws constant thickness focus that is used as template.

  7. Camera Would Monitor Weld-Pool Contours

    NASA Technical Reports Server (NTRS)

    Gordon, Stephen S.; Gutow, David A.

    1990-01-01

    Weld pool illuminated and viewed coaxially along welding torch. Proposed monitoring subsystem for arc welder provides image in which horizontal portions of surface of weld pool highlighted. Monitoring and analyzing subsystems integrated into overall control system of robotic welder. Control system sets welding parameters to adapt to changing conditions, maintaining surface contour giving desired pattern of reflections.

  8. Association between neighborhood socioeconomic status and screen time among pre-school children: a cross-sectional study

    PubMed Central

    2010-01-01

    Background Sedentary behavior is considered a separate construct from physical activity and engaging in sedentary behaviors results in health effects independent of physical activity levels. A major source of sedentary behavior in children is time spent viewing TV or movies, playing video games, and using computers. To date no study has examined the impact of neighborhood socioeconomic status (SES) on pre-school children's screen time behavior. Methods Proxy reports of weekday and weekend screen time (TV/movies, video games, and computer use) were completed by 1633 parents on their 4-5 year-old children in Edmonton, Alberta between November, 2005 and August, 2007. Postal codes were used to classified neighborhoods into low, medium or high SES. Multiple linear and logistic regression models were conducted to examine relationships between screen time and neighborhood SES. Results Girls living in low SES neighborhoods engaged in significantly more weekly overall screen time and TV/movie minutes compared to girls living in high SES neighborhoods. The same relationship was not observed in boys. Children living in low SES neighborhoods were significantly more likely to be video game users and less likely to be computer users compared to children living in high SES neighborhoods. Also, children living in medium SES neighborhoods were significantly less likely to be computer users compared to children living in high SES neighborhoods. Conclusions Some consideration should be given to providing alternative activity opportunities for children, especially girls who live in lower SES neighborhoods. Also, future research should continue to investigate the independent effects of neighborhood SES on screen time as well as the potential mediating variables for this relationship. PMID:20573262

  9. Melodic Contour Identification by Cochlear Implant Listeners

    PubMed Central

    Galvin, John J.; Fu, Qian-Jie; Nogaki, Geraldine

    2013-01-01

    Objective While the cochlear implant provides many deaf patients with good speech understanding in quiet, music perception and appreciation with the cochlear implant remains a major challenge for most cochlear implant users. The present study investigated whether a closed-set melodic contour identification (MCI) task could be used to quantify cochlear implant users’ ability to recognize musical melodies and whether MCI performance could be improved with moderate auditory training. The present study also compared MCI performance with familiar melody identification (FMI) performance, with and without MCI training. Methods For the MCI task, test stimuli were melodic contours composed of 5 notes of equal duration whose frequencies corresponded to musical intervals. The interval between successive notes in each contour was varied between 1 and 5 semitones; the “root note” of the contours was also varied (A3, A4, and A5). Nine distinct musical patterns were generated for each interval and root note condition, resulting in a total of 135 musical contours. The identification of these melodic contours was measured in 11 cochlear implant users. FMI was also evaluated in the same subjects; recognition of 12 familiar melodies was tested with and without rhythm cues. MCI was also trained in 6 subjects, using custom software and melodic contours presented in a different frequency range from that used for testing. Results Results showed that MCI recognition performance was highly variable among cochlear implant users, ranging from 14% to 91% correct. For most subjects, MCI performance improved as the number of semitones between successive notes was increased; performance was slightly lower for the A3 root note condition. Mean FMI performance was 58% correct when rhythm cues were preserved and 29% correct when rhythm cues were removed. Statistical analyses revealed no significant correlation between MCI performance and FMI performance (with or without rhythmic cues). However

  10. Adolescent neighborhood quality predicts adult dACC response to social exclusion

    PubMed Central

    Beckes, Lane; Chango, Joanna; Allen, Joseph P.; Coan, James A.

    2015-01-01

    Neuroimaging studies using the social-exclusion paradigm Cyberball indicate increased dorsal anterior cingulate cortex (dACC) and right insula activity as a function of exclusion. However, comparatively less work has been done on how social status factors may moderate this finding. This study used the Cyberball paradigm with 85 (45 females) socio-economically diverse participants from a larger longitudinal sample. We tested whether neighborhood quality during adolescence would predict subsequent neural responding to social exclusion in young adulthood. Given previous behavioral studies indicating greater social vigilance and negative evaluation as a function of lower status, we expected that lower adolescent neighborhood quality would predict greater dACC activity during exclusion at young adulthood. Our findings indicate that young adults who lived in low-quality neighborhoods in adolescence showed greater dACC activity to social exclusion than those who lived in higher quality neighborhoods. Lower neighborhood quality also predicted greater prefrontal activation in the superior frontal gyrus, dorsal medial prefrontal cortex and the middle frontal gyrus, possibly indicating greater regulatory effort. Finally, this effect was not driven by subsequent ratings of distress during exclusion. In sum, adolescent neighborhood quality appears to potentiate neural responses to social exclusion in young adulthood, effects that are independent of felt distress. PMID:25349459

  11. Validation of walk score for estimating neighborhood walkability: an analysis of four US metropolitan areas.

    PubMed

    Duncan, Dustin T; Aldstadt, Jared; Whalen, John; Melly, Steven J; Gortmaker, Steven L

    2011-11-01

    Neighborhood walkability can influence physical activity. We evaluated the validity of Walk Score(®) for assessing neighborhood walkability based on GIS (objective) indicators of neighborhood walkability with addresses from four US metropolitan areas with several street network buffer distances (i.e., 400-, 800-, and 1,600-meters). Address data come from the YMCA-Harvard After School Food and Fitness Project, an obesity prevention intervention involving children aged 5-11 years and their families participating in YMCA-administered, after-school programs located in four geographically diverse metropolitan areas in the US (n = 733). GIS data were used to measure multiple objective indicators of neighborhood walkability. Walk Scores were also obtained for the participant's residential addresses. Spearman correlations between Walk Scores and the GIS neighborhood walkability indicators were calculated as well as Spearman correlations accounting for spatial autocorrelation. There were many significant moderate correlations between Walk Scores and the GIS neighborhood walkability indicators such as density of retail destinations and intersection density (p < 0.05). The magnitude varied by the GIS indicator of neighborhood walkability. Correlations generally became stronger with a larger spatial scale, and there were some geographic differences. Walk Score(®) is free and publicly available for public health researchers and practitioners. Results from our study suggest that Walk Score(®) is a valid measure of estimating certain aspects of neighborhood walkability, particularly at the 1600-meter buffer. As such, our study confirms and extends the generalizability of previous findings demonstrating that Walk Score is a valid measure of estimating neighborhood walkability in multiple geographic locations and at multiple spatial scales. PMID:22163200

  12. Changes in BMI over 6 years: the role of demographic and neighborhood characteristics

    PubMed Central

    Berry, TR; Spence, JC; Blanchard, C; Cutumisu, N; Edwards, J; Nykiforuk, C

    2016-01-01

    Objective To undertake a 6-year longitudinal investigation of the relationship between the built environment (perceived and objectively measured) and change in body mass index (BMI). Specifically, this research examined whether change in BMI was predicted by objectively measured neighborhood walkability and socioeconomic status (SES), and perceived neighborhood characteristics (for example, crime, traffic and interesting things to look at) in addition to other factors such as age, gender, education, physical activity, fruit and vegetable consumption and smoking. Design Longitudinal study Subjects 500 adults who provided complete data in 2002 and 2008 and who did not move over the course of the study (47.8% female; age in 2002: 18–90 years). Measurements Telephone surveys in 2002 and 2008 measuring perceptions of their neighborhood environment and demographic factors. Objective measures of neighborhood characteristics were calculated using census data and geographical information systems in 2006. Results Age, neighborhood SES and perceived traffic were significantly related to increased BMI over the 6 years. Younger participants and those in lower SES neighborhoods were more likely to have increased BMI. Agreement with the statement that traffic made it difficult to walk also predicted increased BMI. Conclusion This study adds to the literature to show that BMI increased in low SES neighborhoods. Although more research is needed to fully understand how neighborhood SES contributes to obesity, it is without question that individuals in socially disadvantaged neighborhoods face more barriers to health than their wealthier counterparts. This study also calls into question the relationship between walkability and changes in BMI and emphasizes the necessity of longitudinal data rather than relying on cross-sectional research. PMID:20157324

  13. Assessment of Neighborhood Context in a Nationally Representative Study

    PubMed Central

    Cagney, Kathleen A.

    2014-01-01

    Objectives. This paper introduces new measures of neighborhood context that are included in the second wave of the National Social Life, Health, and Aging Project (NSHAP). We describe the use of field interviewer ratings of respondents’ neighborhood conditions, as well as the adaptation of existing measures for the assessment of neighborhood social context among urban and nonurban older adults. Method. We construct scales of neighborhood problems, neighborhood social cohesion, neighborhood social ties, and perceived neighborhood danger, and assess their reliability and validity. We then calculate descriptive statistics for measures of neighborhood context across respondent age, gender, and racial/ethnic background, and across low-, moderate-, and high-density residential blocks. Results. We find that older women report greater neighborhood cohesion and more neighborhood ties than older men, but women also perceive more neighborhood danger. Black and Hispanic older adults reside in neighborhoods with more problems, lower cohesion, fewer social ties, and greater perceived danger. Neighborhood characteristics also vary across residential densities. Neighborhood problems and perceived danger increase with block-level density, but neighborhood social cohesion and social ties were lowest among residents of moderate-density blocks. Discussion. The inclusion of neighborhood context measures in the second wave of NSHAP provides a unique opportunity to explore associations among neighborhood context, social connectedness, and indicators of health and function among older adults. We discuss limitations of the measures and provide recommendations for their use. PMID:24875376

  14. Associations of perceived neighborhood safety and crime with cardiometabolic risk factors among a population with type 2 diabetes.

    PubMed

    Tamayo, Aracely; Karter, Andrew J; Mujahid, Mahasin S; Warton, E Margaret; Moffet, Howard H; Adler, Nancy; Schillinger, Dean; Hendrickson O'Connell, Bethany; Laraia, Barbara

    2016-05-01

    Little is known about how neighborhood crime may relate to health in diabetes patients. We examined associations between individuals' perceptions of neighborhood safety or violent crime and stress, physical activity, body mass index (BMI) or hemoglobin A1c (HbA1c) in a sample (n=721) of adults (mean age:63) with diabetes. Self-reported neighborhood safety, violent crime, physical activity, and stress were collected and linked to clinical measures of BMI and HbA1c. Approximately 54% and 15% of patients reported neighborhood safety concerns and violent crimes, respectively. Any neighborhood safety concerns (β=1.14, 95% C.I. 0.04-2.24) and violent crime (β=2.04, 95% C.I. 0.34-3.73) were associated with BMI in adjusted analysis. Any violent crime was associated with class II-III obesity (BMI≥35) (OR=1.34, 95% C.I.: 1.02, 1.75). There were no significant associations between neighborhood safety concerns or violent crime with stress, physical activity, or HbA1c. Neighborhood safety is associated with BMI and obesity. Further studies, including longitudinal designs, are needed to study how people with diabetes may be influenced by a sense of poor personal safety in their neighborhoods. PMID:27060870

  15. Neighborhoods and Adolescent Health-Risk Behavior: An Ecological Network Approach1

    PubMed Central

    Browning, Christopher R.; Soller, Brian; Jackson, Aubrey L.

    2014-01-01

    This study integrates insights from social network analysis, activity space perspectives, and theories of urban and spatial processes to present an innovative approach to neighborhood effects on health-risk behavior among youth. We suggest spatial patterns of neighborhood residents’ non-home routine activities may be conceptualized as ecological, or “eco”-networks, which are two-mode networks that indirectly link residents through socio-spatial overlap in routine activities. We further argue structural configurations of eco-networks are consequential for youth’s behavioral health. In this study we focus on a key structural feature of eco-networks—the neighborhood-level extent to which households share two or more activity locations, or eco-network reinforcement—and its association with two dimensions of health-risk behavior, substance use and delinquency/sexual activity. Using geographic data on non-home routine activity locations among respondents from the Los Angeles Family and Neighborhood Survey (L.A.FANS), we constructed neighborhood-specific eco-networks by connecting sampled households to “activity clusters,” which are sets of spatially-proximate activity locations. We then measured eco-network reinforcement and examined its association with adolescent dimensions of health risk behavior employing a sample of 830 youth ages 12-17 nested in 65 census tracts. We also examined whether neighborhood-level social processes (collective efficacy and intergenerational closure) mediate the association between eco-network reinforcement and the outcomes considered. Results indicated eco-network reinforcement exhibits robust negative associations with both substance use and delinquency/sexual activity scales. Eco-network reinforcement effects were not explained by potential mediating variables. In addition to introducing a novel theoretical and empirical approach to neighborhood effects on youth, our findings highlight the importance of eco

  16. The Neighborhood Context of Homelessness

    PubMed Central

    Pollio, David E.; North, Carol S.

    2013-01-01

    Objectives. We examined and compared the changing neighborhood characteristics of a group of homeless adults over time. Methods. We collected the addresses of previous housing and sleep locations from a longitudinal study of 400 homeless adults in the St. Louis, Missouri, region and compared census measures of housing and economic opportunities at different points along individual pathways from housing to homelessness and at 1- and 2-year follow-up interviews. Results. Sleep locations of homeless adults were much more concentrated in the urban core at baseline than were their previous housed and follow-up locations. These core areas had higher poverty, unemployment, and rent-to-income ratios and lower median incomes. Conclusions. The spatial concentration of homeless adults in areas with fewer opportunities and more economic and housing distress may present additional barriers to regaining stable housing and employment. A big-picture spatial and time-course viewpoint is critical for both policymakers and future homelessness researchers. PMID:23409889

  17. Automatic Contour Detection Using a "Fixed-Point Hachimura-Kuwahara Filter" for SPECT Attenuation Correction.

    PubMed

    Minato, K; Tang, Y N; Bennett, G W; Brill, A

    1987-01-01

    Attenuation correction for single-photon emission computed tomography (SPECT) usually assumes a uniform attenuation distribution within the body surface contour. Previous methods to estimate this contour have used thresholding of a reconstructed section image. This method is often very sensitive to the selection of a threshold value, especially for nonuniform activity distributions within the body. We have proposed the "fixed-point Hachimura-Kuwahara filter" to extract contour primitives from SPECT images. The Hachimura-Kuwahara filter, which preserves edges but smoothes nonedge regions, is applied repeatedly to identify the invariant set-the fixed-point image-which is unchanged by this nonlinear, two-dimensional filtering operation. This image usually becomes a piecewise constant array. In order to detect the contour, the tracing algorithm based on the minimum distance connection criterion is applied to the extracted contour primitives. This procedure does not require choice of a threshold value in determining the contour. SPECT data from a water-filled elliptical phantom containing three sources was obtained and scattered projections were reconstructed. The automatic edge detection procedure was applied to the scattered window reconstruction, resulting in a reasonable outline of the phantom. PMID:18230438

  18. Automatic Endocardium Contour Tracing Method Using Standard Left Ventricles Shape Model

    NASA Astrophysics Data System (ADS)

    Horie, Masahiro; Kashima, Masayuki; Sato, Kiminori; Watanabe, Mutsumi

    The necessity of ultrasonic diagnosis tools increases every year. We propose an automatic endocardium tracing method by applying prepared “Standard Left Ventricles Shape Model (SLVSM)”. The cross section of heart wall in ultrasonic image is decided depending on the position and the angle of this probe. The initial contour is adaptively determined as crossing curve line between the SLVSM and the cross section. And the endocardium contour is extracted by active contour model(ACM) in two stages. In the first stage, an endocardium contour is detected using the result of an edge extraction based on the separability of image features. In the second stage, the endocardium contour is extracted using shape correction processing. “Mitral valve processing” not only detects the position of the mitral valve at the end diastolic period, but also corrects the detected contour after the first stage of ACM. Experimental results using one healthy case and three diseased cases have shown the effectiveness of the proposed method.

  19. Geometrical Tile Design for Complex Neighborhoods

    PubMed Central

    Czeizler, Eugen; Kari, Lila

    2009-01-01

    Recent research has showed that tile systems are one of the most suitable theoretical frameworks for the spatial study and modeling of self-assembly processes, such as the formation of DNA and protein oligomeric structures. A Wang tile is a unit square, with glues on its edges, attaching to other tiles and forming larger and larger structures. Although quite intuitive, the idea of glues placed on the edges of a tile is not always natural for simulating the interactions occurring in some real systems. For example, when considering protein self-assembly, the shape of a protein is the main determinant of its functions and its interactions with other proteins. Our goal is to use geometric tiles, i.e., square tiles with geometrical protrusions on their edges, for simulating tiled paths (zippers) with complex neighborhoods, by ribbons of geometric tiles with simple, local neighborhoods. This paper is a step toward solving the general case of an arbitrary neighborhood, by proposing geometric tile designs that solve the case of a “tall” von Neumann neighborhood, the case of the f-shaped neighborhood, and the case of a 3 × 5 “filled” rectangular neighborhood. The techniques can be combined and generalized to solve the problem in the case of any neighborhood, centered at the tile of reference, and included in a 3 × (2k + 1) rectangle. PMID:19956398

  20. Geometrical tile design for complex neighborhoods.

    PubMed

    Czeizler, Eugen; Kari, Lila

    2009-01-01

    Recent research has showed that tile systems are one of the most suitable theoretical frameworks for the spatial study and modeling of self-assembly processes, such as the formation of DNA and protein oligomeric structures. A Wang tile is a unit square, with glues on its edges, attaching to other tiles and forming larger and larger structures. Although quite intuitive, the idea of glues placed on the edges of a tile is not always natural for simulating the interactions occurring in some real systems. For example, when considering protein self-assembly, the shape of a protein is the main determinant of its functions and its interactions with other proteins. Our goal is to use geometric tiles, i.e., square tiles with geometrical protrusions on their edges, for simulating tiled paths (zippers) with complex neighborhoods, by ribbons of geometric tiles with simple, local neighborhoods. This paper is a step toward solving the general case of an arbitrary neighborhood, by proposing geometric tile designs that solve the case of a "tall" von Neumann neighborhood, the case of the f-shaped neighborhood, and the case of a 3 x 5 "filled" rectangular neighborhood. The techniques can be combined and generalized to solve the problem in the case of any neighborhood, centered at the tile of reference, and included in a 3 x (2k + 1) rectangle. PMID:19956398

  1. Automatic liver contouring for radiotherapy treatment planning.

    PubMed

    Li, Dengwang; Liu, Li; Kapp, Daniel S; Xing, Lei

    2015-10-01

    To develop automatic and efficient liver contouring software for planning 3D-CT and four-dimensional computed tomography (4D-CT) for application in clinical radiation therapy treatment planning systems.The algorithm comprises three steps for overcoming the challenge of similar intensities between the liver region and its surrounding tissues. First, the total variation model with the L1 norm (TV-L1), which has the characteristic of multi-scale decomposition and an edge-preserving property, is used for removing the surrounding muscles and tissues. Second, an improved level set model that contains both global and local energy functions is utilized to extract liver contour information sequentially. In the global energy function, the local correlation coefficient (LCC) is constructed based on the gray level co-occurrence matrix both of the initial liver region and the background region. The LCC can calculate the correlation of a pixel with the foreground and background regions, respectively. The LCC is combined with intensity distribution models to classify pixels during the evolutionary process of the level set based method. The obtained liver contour is used as the candidate liver region for the following step. In the third step, voxel-based texture characterization is employed for refining the liver region and obtaining the final liver contours.The proposed method was validated based on the planning CT images of a group of 25 patients undergoing radiation therapy treatment planning. These included ten lung cancer patients with normal appearing livers and ten patients with hepatocellular carcinoma or liver metastases. The method was also tested on abdominal 4D-CT images of a group of five patients with hepatocellular carcinoma or liver metastases. The false positive volume percentage, the false negative volume percentage, and the dice similarity coefficient between liver contours obtained by a developed algorithm and a current standard delineated by the expert group

  2. Automatic liver contouring for radiotherapy treatment planning

    NASA Astrophysics Data System (ADS)

    Li, Dengwang; Liu, Li; Kapp, Daniel S.; Xing, Lei

    2015-09-01

    To develop automatic and efficient liver contouring software for planning 3D-CT and four-dimensional computed tomography (4D-CT) for application in clinical radiation therapy treatment planning systems. The algorithm comprises three steps for overcoming the challenge of similar intensities between the liver region and its surrounding tissues. First, the total variation model with the L1 norm (TV-L1), which has the characteristic of multi-scale decomposition and an edge-preserving property, is used for removing the surrounding muscles and tissues. Second, an improved level set model that contains both global and local energy functions is utilized to extract liver contour information sequentially. In the global energy function, the local correlation coefficient (LCC) is constructed based on the gray level co-occurrence matrix both of the initial liver region and the background region. The LCC can calculate the correlation of a pixel with the foreground and background regions, respectively. The LCC is combined with intensity distribution models to classify pixels during the evolutionary process of the level set based method. The obtained liver contour is used as the candidate liver region for the following step. In the third step, voxel-based texture characterization is employed for refining the liver region and obtaining the final liver contours. The proposed method was validated based on the planning CT images of a group of 25 patients undergoing radiation therapy treatment planning. These included ten lung cancer patients with normal appearing livers and ten patients with hepatocellular carcinoma or liver metastases. The method was also tested on abdominal 4D-CT images of a group of five patients with hepatocellular carcinoma or liver metastases. The false positive volume percentage, the false negative volume percentage, and the dice similarity coefficient between liver contours obtained by a developed algorithm and a current standard delineated by the expert group

  3. Neighborhood Factors and Dating Violence Among Youth

    PubMed Central

    Johnson, Renee M.; Parker, Elizabeth M.; Rinehart, Jenny; Nail, Jennifer; Rothman, Emily F.

    2015-01-01

    Context The purpose of this review is to summarize the empirical research on neighborhood-level factors and dating violence among adolescents and emerging adults to guide future research and practice. Evidence acquisition In 2015, 20 articles were identified through a search of the literature using PubMed. Eligible articles included those that: (1) had been published in a peer-reviewed journal since 2005; (2) reported a measure of association between at least one neighborhood-level factor and dating violence; and (3) had a study population of youth aged <26 years. We abstracted information about the studies, including measurement of dating violence and neighborhood factors, and measures of effect. Evidence synthesis Results were summarized into three categories based on the aspect of neighborhood which was the focus of the work: demographic and structural characteristics (n=11), neighborhood disorder (n=12), and social disorganization (n=8). There was some evidence to suggest that neighborhood disadvantage is associated with dating violence, but very little evidence to suggest that residence characteristics (e.g., racial heterogeneity) are associated with dating violence. Results do suggest that perceived neighborhood disorder is associated with physical dating violence perpetration, but do not suggest that it is associated with physical dating violence victimization. Social control and community connectedness are both associated with dating violence, but findings on collective efficacy are mixed. Conclusions Existing research suggests that neighborhood factors may be associated with dating violence. However, there is a limited body of research on the neighborhood context of dating violence and more rigorous research is needed. PMID:26296444

  4. Star-formation Activity in the Neighborhood of W–R 1503-160L Star in the Mid-infrared Bubble N46

    NASA Astrophysics Data System (ADS)

    Dewangan, L. K.; Baug, T.; Ojha, D. K.; Janardhan, P.; Ninan, J. P.; Luna, A.; Zinchenko, I.

    2016-07-01

    In order to investigate star-formation (SF) processes in extreme environments, we have carried out a multi-wavelength analysis of the mid-infrared bubble N46, which hosts a WN7 Wolf–Rayet (W–R) star. We have used 13CO line data to trace an expanding shell surrounding the W–R star containing about five condensations within the molecular cloud associated with the bubble. The W–R star is associated with a powerful stellar wind having a mechanical luminosity of ˜4 × 1037 erg s‑1. A deviation of the H-band starlight mean polarization angles around the bubble has also been traced, indicating the impact of stellar wind on the surroundings. The Herschel temperature map shows a temperature range of ˜18–24 K toward the five molecular condensations. The photometric analysis reveals that these condensations are associated with the identified clusters of young stellar objects, revealing ongoing SF process. The densest among these five condensations (peak N(H2) ˜9.2 × 1022 cm‑2 and A V ˜ 98 mag) is associated with a 6.7 GHz methanol maser, an infrared dark cloud, and the CO outflow, tracing active massive SF within it. At least five compact radio sources (CRSs) are physically linked with the edges of the bubble, and each of them is consistent with the radio spectral class of a B0V–B0.5V-type star. The ages of the individual infrared counterparts of three CRSs (˜1–2 Myr) and a typical age of WN7 W–R star (˜4 Myr) indicate that the SF activities around the bubble are influenced by the feedback of the W–R star.

  5. Star-formation Activity in the Neighborhood of W–R 1503-160L Star in the Mid-infrared Bubble N46

    NASA Astrophysics Data System (ADS)

    Dewangan, L. K.; Baug, T.; Ojha, D. K.; Janardhan, P.; Ninan, J. P.; Luna, A.; Zinchenko, I.

    2016-07-01

    In order to investigate star-formation (SF) processes in extreme environments, we have carried out a multi-wavelength analysis of the mid-infrared bubble N46, which hosts a WN7 Wolf–Rayet (W–R) star. We have used 13CO line data to trace an expanding shell surrounding the W–R star containing about five condensations within the molecular cloud associated with the bubble. The W–R star is associated with a powerful stellar wind having a mechanical luminosity of ∼4 × 1037 erg s‑1. A deviation of the H-band starlight mean polarization angles around the bubble has also been traced, indicating the impact of stellar wind on the surroundings. The Herschel temperature map shows a temperature range of ∼18–24 K toward the five molecular condensations. The photometric analysis reveals that these condensations are associated with the identified clusters of young stellar objects, revealing ongoing SF process. The densest among these five condensations (peak N(H2) ∼9.2 × 1022 cm‑2 and A V ∼ 98 mag) is associated with a 6.7 GHz methanol maser, an infrared dark cloud, and the CO outflow, tracing active massive SF within it. At least five compact radio sources (CRSs) are physically linked with the edges of the bubble, and each of them is consistent with the radio spectral class of a B0V–B0.5V-type star. The ages of the individual infrared counterparts of three CRSs (∼1–2 Myr) and a typical age of WN7 W–R star (∼4 Myr) indicate that the SF activities around the bubble are influenced by the feedback of the W–R star.

  6. Neighborhood Context and Immigrant Young Children's Development

    ERIC Educational Resources Information Center

    Leventhal, Tama; Shuey, Elizabeth A.

    2014-01-01

    This study explored how neighborhood social processes and resources, relevant to immigrant families and immigrant neighborhoods, contribute to young children's behavioral functioning and achievement across diverse racial/ethnic groups. Data were drawn from the Project on Human Development in Chicago Neighborhoods, a neighborhood-based,…

  7. 47 CFR 73.311 - Field strength contours.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Field strength contours. 73.311 Section 73.311... Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate. (b)...

  8. 47 CFR 73.311 - Field strength contours.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Field strength contours. 73.311 Section 73.311... Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate. (b)...

  9. 47 CFR 73.311 - Field strength contours.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Field strength contours. 73.311 Section 73.311... Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate. (b)...

  10. 47 CFR 73.311 - Field strength contours.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Field strength contours. 73.311 Section 73.311... Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate. (b)...

  11. 47 CFR 73.311 - Field strength contours.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Field strength contours. 73.311 Section 73.311... Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate. (b)...

  12. Thermal contouring of forestry data: Wallops Island

    NASA Technical Reports Server (NTRS)

    Thomson, F.

    1972-01-01

    The contouring of 8-13.5 micrometer thermal data collected over a forestry site in Virginia is described. The data were collected at an altitude of 1000 ft above terrain on November 4, 1970. The site was covered on three approximately parallel lines. The purpose of the contouring was to attempt to delineate pine trees attacked by southern pine bark beetle, and to map other important terrain categories. Special processing steps were required to achieve the correct aspect ratio of the thermal data. The reference for the correction procedure was color infrared photography. Data form and quality are given, processing steps are outlined, a brief interpretation of results is given, and conclusion are presented.

  13. EFFICIENT FEATURE-BASED CONTOUR EXTRACTION.

    SciTech Connect

    Gattiker, J. R.

    2001-01-01

    Extraction of contours in binary images is an important element of object recognition. This paper discusses a more efficient approach to contour representation and generation. This approach defines a bounding polygon as defined by its vertices rather than by all enclosing pixels, which in itself is an effective representation. These corners can be identified by convolution of the image with a 3 x 3 filter. When these corners are organized by their connecting orientation, identified by the convolution, and type, inside or outside, connectivity characteristics can be articulated to highly constrain the task of sorting the vertices into ordered boundary lists. The search for the next bounding polygon vertex is reduced to a one dimensional minimum distance search rather than the standard, more intensive two dimensional nearest Euclidean neighbor search.

  14. Contour forming of metals by laser peening

    DOEpatents

    Hackel, Lloyd; Harris, Fritz

    2002-01-01

    A method and apparatus are provided for forming shapes and contours in metal sections by generating laser induced compressive stress on the surface of the metal workpiece. The laser process can generate deep compressive stresses to shape even thick components without inducing unwanted tensile stress at the metal surface. The precision of the laser-induced stress enables exact prediction and subsequent contouring of parts. A light beam of 10 to 100 J/pulse is imaged to create an energy fluence of 60 to 200 J/cm.sup.2 on an absorptive layer applied over a metal surface. A tamping layer of water is flowed over the absorptive layer. The absorption of laser light causes a plasma to form and consequently creates a shock wave that induces a deep residual compressive stress into the metal. The metal responds to this residual stress by bending.

  15. The solar neighborhood. XXXIII. Parallax results from the CTIOPI 0.9 m program: trigonometric parallaxes of Nearby low-mass active and young systems

    SciTech Connect

    Riedel, Adric R.; Cruz, Kelle L.; Finch, Charlie T.; Henry, Todd J.; Jao, Wei-Chun; White, Russel J.; Gies, Douglas R.; Dieterich, Sergio B.; Winters, Jennifer G.; Davison, Cassy L.; Subasavage, John P.; Malo, Lison; Rodriguez, David R.; Nelan, Edmund P.; Blunt, Sarah C.; Rice, Emily L.; Ianna, Philip A.

    2014-04-01

    We present basic observational data and association membership analysis for 45 young and active low-mass stellar systems from the ongoing Research Consortium On Nearby Stars photometry and astrometry program at the Cerro Tololo Inter-American Observatory. Most of these systems have saturated X-ray emission (log (L{sub X} /L {sub bol}) > –3.5) based on X-ray fluxes from the ROSAT All-Sky Survey, and many are significantly more luminous than main-sequence stars of comparable color. We present parallaxes and proper motions, Johnson-Kron-Cousins VRI photometry, and multiplicity observations from the CTIOPI program on the CTIO 0.9 m telescope. To this we add low-resolution optical spectroscopy and line measurements from the CTIO 1.5 m telescope, and interferometric binary measurements from the Hubble Space Telescope Fine Guidance Sensors. We also incorporate data from published sources: JHK{sub S} photometry from the Two Micron All Sky Survey point source catalog, X-ray data from the ROSAT All-Sky Survey, and radial velocities from literature sources. Within the sample of 45 systems, we identify 21 candidate low-mass pre-main-sequence members of nearby associations, including members of β Pictoris, TW Hydrae, Argus, AB Doradus, two ambiguous ≈30 Myr old systems, and one object that may be a member of the Ursa Major moving group. Of the 21 candidate young systems, 14 are newly identified as a result of this work, and six of those are within 25 pc of the Sun.

  16. Contribution of the Neighborhood Environment and Obesity to Breast Cancer Survival: The California Breast Cancer Survivorship Consortium

    PubMed Central

    Cheng, Iona; Shariff-Marco, Salma; Koo, Jocelyn; Monroe, Kristine R.; Yang, Juan; John, Esther M.; Kurian, Allison W.; Kwan, Marilyn L.; Henderson, Brian E.; Bernstein, Leslie; Lu, Yani; Sposto, Richard; Vigen, Cheryl; Wu, Anna H.; Gomez, Scarlett Lin; Keegan, Theresa H.M.

    2015-01-01

    Little is known about neighborhood attributes that may influence opportunities for healthy eating and physical activity in relation to breast cancer mortality. We used data from the California Breast Cancer Survivorship Consortium and the California Neighborhoods Data System to examine the neighborhood environment, body mass index, and mortality after breast cancer. We studied 8,995 African American, Asian American, Latina, and non-Latina White women with breast cancer. Residential addresses were linked to the CNDS to characterize neighborhoods. We used multinomial logistic regression to evaluate the associations between neighborhood factors and obesity, and Cox proportional hazards regression to examine associations between neighborhood factors and mortality. For Latinas, obesity was associated with more neighborhood crowding (Quartile 4 (Q4) vs. Q1: Odds Ratio (OR)=3.24; 95% Confidence Interval (CI): 1.50-7.00); breast cancer-specific mortality was inversely associated with neighborhood businesses (Q4 vs. Q1: Hazard Ratio (HR)=0.46; 95% CI: 0.25-0.85) and positively associated with multi-family housing (Q3 vs. Q1: HR=1.98; 95% CI: 1.20-3.26). For non-Latina Whites, lower neighborhood socioeconomic status (SES) was associated with obesity (Quintile 1 (Q1) vs. Q5: OR=2.52; 95% CI: 1.31-4.84), breast cancer-specific (Q1 vs. Q5: HR=2.75; 95% CI: 1.47-5.12), and all-cause (Q1 vs. Q5: HR=1.75; 95% CI: 1.17-2.62) mortality. For Asian Americans, no associations were seen. For African Americans, lower neighborhood SES was associated with lower mortality in a nonlinear fashion. Attributes of the neighborhood environment were associated with obesity and mortality following breast cancer diagnosis, but these associations differed across racial/ethnic groups. PMID:26063477

  17. Numerosity underestimation in sets with illusory contours.

    PubMed

    Kirjakovski, Atanas; Matsumoto, Eriko

    2016-05-01

    People underestimate the numerosity of collections in which a few dots are connected in pairs by task-irrelevant lines. Such configural processing suggests that visual numerosity depends on the perceived scene segments, rather than on the perceived total area occupied by a collection. However, a methodology that uses irrelevant line connections may also introduce unnecessary distraction and variety, or obscure the perception of task-relevant items, given the saliency of the lines. To avoid such potentially confounding variables, we conducted four experiments where the line-connected dots were replaced with collinear inducers of Kanizsa-type illusory contours. Our participants had to compare two simultaneously presented collections and choose the more numerous one. Displays comprised c-shaped inducers and disks (Experiment 1), c-shaped inducers only (Experiments 2 and 4), or closed inducers (Experiment 3). One display always showed a 12- (Experiments 1-3) or 48-item reference pattern (Experiment 4); the other was a test pattern with numerosity varying between 9 and 15 (Experiments 1-3) or 36-60 items (Experiment 4). By manipulating the number of illusory contours in the test patterns, the level of connectedness increased or decreased respectively. The fitted psychometric functions revealed an underestimation that increased with the number of illusory contours in Experiments 1 and 2, but was absent in Experiments 3 and 4, where illusory contours were more difficult to perceive or larger numerosities were used. Results corroborate claims that visual numerosity estimation depends on segmented inputs, but only within moderate numerical ranges. PMID:27038561

  18. Semi-automated contour recognition using DICOMautomaton

    NASA Astrophysics Data System (ADS)

    Clark, H.; Wu, J.; Moiseenko, V.; Lee, R.; Gill, B.; Duzenli, C.; Thomas, S.

    2014-03-01

    Purpose: A system has been developed which recognizes and classifies Digital Imaging and Communication in Medicine contour data with minimal human intervention. It allows researchers to overcome obstacles which tax analysis and mining systems, including inconsistent naming conventions and differences in data age or resolution. Methods: Lexicographic and geometric analysis is used for recognition. Well-known lexicographic methods implemented include Levenshtein-Damerau, bag-of-characters, Double Metaphone, Soundex, and (word and character)-N-grams. Geometrical implementations include 3D Fourier Descriptors, probability spheres, boolean overlap, simple feature comparison (e.g. eccentricity, volume) and rule-based techniques. Both analyses implement custom, domain-specific modules (e.g. emphasis differentiating left/right organ variants). Contour labels from 60 head and neck patients are used for cross-validation. Results: Mixed-lexicographical methods show an effective improvement in more than 10% of recognition attempts compared with a pure Levenshtein-Damerau approach when withholding 70% of the lexicon. Domain-specific and geometrical techniques further boost performance. Conclusions: DICOMautomaton allows users to recognize contours semi-automatically. As usage increases and the lexicon is filled with additional structures, performance improves, increasing the overall utility of the system.

  19. Inlet contour and flow effects on radiation

    NASA Technical Reports Server (NTRS)

    Ville, J. M.; Silcox, R. J.

    1980-01-01

    An experimental investigation of sound radiation from inlets with different contours with and without flow is being conducted to study the possibility of reducing noise radiated by aircraft engines. For each inlet configuration, complex directivity patterns and complex pressure reflection coefficients are measured as a function of a single space-time structure of the wave (up to a frequency of 4000Hz and an azimuthal wave number 6) and of flow velocity (up to Mach number 0.4) in a cylindrical duct located downstream the inlet. Experimental results of radiation from an unflanged duct are compared with theory. Effect of inlet contour and flow are deduced by comparing respectively unflanged duct and bellmouth measurements and, no flow and flow measurements with the bellmouth. Results are presented which indicate that the contour effect is significant near the cut-on frequency of a mode and emphasize the necessity for taking into account the inlet geometry in a radiation prediction. These results show also that internal flow has a weak effect on the amplitude of the directivity pattern

  20. Inlet contour and flow effects on radiation

    NASA Astrophysics Data System (ADS)

    Ville, J. M.; Silcox, R. J.

    1980-06-01

    An experimental investigation of sound radiation from inlets with different contours with and without flow is being conducted to study the possibility of reducing noise radiated by aircraft engines. For each inlet configuration, complex directivity patterns and complex pressure reflection coefficients are measured as a function of a single space-time structure of the wave (up to a frequency of 4000Hz and an azimuthal wave number 6) and of flow velocity (up to Mach number 0.4) in a cylindrical duct located downstream the inlet. Experimental results of radiation from an unflanged duct are compared with theory. Effect of inlet contour and flow are deduced by comparing respectively unflanged duct and bellmouth measurements and, no flow and flow measurements with the bellmouth. Results are presented which indicate that the contour effect is significant near the cut-on frequency of a mode and emphasize the necessity for taking into account the inlet geometry in a radiation prediction. These results show also that internal flow has a weak effect on the amplitude of the directivity pattern

  1. Breast Contour Detection with Stable Paths

    NASA Astrophysics Data System (ADS)

    Cardoso, Jaime S.; Sousa, Ricardo; Teixeira, Luís F.; Cardoso, M. J.

    Breast cancer conservative treatment (BCCT), due to its proven oncological safety, is considered, when feasible, the gold standard of breast cancer treatment. However, aesthetic results are heterogeneous and difficult to evaluate in a standardized way, due to the lack of reproducibility of the subjective methods usually applied. The objective assessment methods, considered in the past as being less capable of evaluating all aspects of BCCT, are nowadays being preferred to overcome the drawbacks of the subjective evaluation. A computer-aided medical system was recently developed to objectively and automatically evaluate the aesthetic result of BCCT. In this system, the detection of the breast contour on the patient's digital photograph is a necessary step to extract the features subsequently used in the evaluation process. In this paper an algorithm based on the shortest path on a graph is proposed to detect automatically the breast contour. The proposed method extends an existing semi-automatic algorithm for the same purpose. A comprehensive comparison with manually-drawn contours reveals the strength of the proposed method.

  2. Contour-Driven Atlas-Based Segmentation.

    PubMed

    Wachinger, Christian; Fritscher, Karl; Sharp, Greg; Golland, Polina

    2015-12-01

    We propose new methods for automatic segmentation of images based on an atlas of manually labeled scans and contours in the image. First, we introduce a Bayesian framework for creating initial label maps from manually annotated training images. Within this framework, we model various registration- and patch-based segmentation techniques by changing the deformation field prior. Second, we perform contour-driven regression on the created label maps to refine the segmentation. Image contours and image parcellations give rise to non-stationary kernel functions that model the relationship between image locations. Setting the kernel to the covariance function in a Gaussian process establishes a distribution over label maps supported by image structures. Maximum a posteriori estimation of the distribution over label maps conditioned on the outcome of the atlas-based segmentation yields the refined segmentation. We evaluate the segmentation in two clinical applications: the segmentation of parotid glands in head and neck CT scans and the segmentation of the left atrium in cardiac MR angiography images. PMID:26068202

  3. Challenges and complications in neighborhood mapping: from neighborhood concept to operationalization

    NASA Astrophysics Data System (ADS)

    Deng, Yongxin

    2016-07-01

    This paper examines complications in neighborhood mapping and corresponding challenges for the GIS community, taking both a conceptual and a methodological perspective. It focuses on the social and spatial dimensions of the neighborhood concept and highlights their relationship in neighborhood mapping. Following a brief summary of neighborhood definitions, five interwoven factors are identified to be origins of neighborhood mapping difficulties: conceptual vagueness, uncertainty of various sources, GIS representation, scale, and neighborhood homogeneity or continuity. Existing neighborhood mapping methods are grouped into six categories to be assessed: perception based, physically based, inference based, preexisting, aggregated, and automated. Mapping practices in various neighborhood-related disciplines and applications are cited as examples to demonstrate how the methods work, as well as how they should be evaluated. A few mapping strategies for the improvement of neighborhood mapping are prescribed from a GIS perspective: documenting simplifications employed in the mapping procedure, addressing uncertainty sources, developing new data solutions, and integrating complementary mapping methods. Incorporation of high-resolution data and introduction of more GIS ideas and methods (such as fuzzy logic) are identified to be future opportunities.

  4. Challenges and complications in neighborhood mapping: from neighborhood concept to operationalization

    NASA Astrophysics Data System (ADS)

    Deng, Yongxin

    2016-05-01

    This paper examines complications in neighborhood mapping and corresponding challenges for the GIS community, taking both a conceptual and a methodological perspective. It focuses on the social and spatial dimensions of the neighborhood concept and highlights their relationship in neighborhood mapping. Following a brief summary of neighborhood definitions, five interwoven factors are identified to be origins of neighborhood mapping difficulties: conceptual vagueness, uncertainty of various sources, GIS representation, scale, and neighborhood homogeneity or continuity. Existing neighborhood mapping methods are grouped into six categories to be assessed: perception based, physically based, inference based, preexisting, aggregated, and automated. Mapping practices in various neighborhood-related disciplines and applications are cited as examples to demonstrate how the methods work, as well as how they should be evaluated. A few mapping strategies for the improvement of neighborhood mapping are prescribed from a GIS perspective: documenting simplifications employed in the mapping procedure, addressing uncertainty sources, developing new data solutions, and integrating complementary mapping methods. Incorporation of high-resolution data and introduction of more GIS ideas and methods (such as fuzzy logic) are identified to be future opportunities.

  5. Effects of neighborhood violence and perceptions of neighborhood safety on depressive symptoms of older adults.

    PubMed

    Wilson-Genderson, Maureen; Pruchno, Rachel

    2013-05-01

    Violent crime within a neighborhood as well as perceptions of neighborhood safety may impact the depressive symptoms experienced by community-dwelling older people. Most studies examining the influences of neighborhood characteristics on mental health have included either objective indicators or subjective perceptions and most operationalize neighborhood as a function of socioeconomic status. This study examines the effects that objectively assessed neighborhood violent crime and subjective perceptions of neighborhood safety in tandem have on depressive symptoms. The sample identified using random-digit-dialing procedures included 5688 persons aged 50-74 living in New Jersey (USA). Using multilevel structural equation analyses, we tested the hypothesis that higher levels of neighborhood violent crime and poorer perceptions of neighborhood safety are associated with higher levels of depressive symptoms, controlling for age, sex, and household income. Results supported the hypotheses. We conclude that interventions at the neighborhood level that reduce violent crime may be needed to compliment efforts at the individual level in order to reduce the depressive symptoms experienced by older people. PMID:23540365

  6. Neighborhood socioeconomic deprivation, perceived neighborhood factors, and cortisol responses to induced stress among healthy adults.

    PubMed

    Barrington, Wendy E; Stafford, Mai; Hamer, Mark; Beresford, Shirley A A; Koepsell, Thomas; Steptoe, Andrew

    2014-05-01

    Associations between measures of neighborhood socioeconomic deprivation and health have been identified, yet work is needed to uncover explanatory mechanisms. One hypothesized pathway is through stress, yet the few studies that have evaluated associations between characteristics of deprived neighborhoods and biomarkers of stress are mixed. This study evaluated whether objectively measured neighborhood socioeconomic deprivation and individual perceived neighborhood characteristics (i.e. social control and fear of crime) impacted cortisol responses to an induced stressor among older healthy adults. Data from Heart Scan, a sub-study of the Whitehall II cohort, were used to generate multilevel piecewise growth-curve models of cortisol trajectories after a laboratory stressor accounting for neighborhood and demographic characteristics. Neighborhood socioeconomic deprivation was significantly associated with individual perceptions of social control and fear of crime in the neighborhood while an association with blunted cortisol reactivity was only evidence among women. Social control was significantly associated with greater cortisol reactivity and mediation between neighborhood socioeconomic deprivation and cortisol reactivity was suggested among women. These findings support a gender-dependent role of neighborhood in stress process models of health. PMID:24603009

  7. Functional Limitations and Gender Differences: Neighborhood Effects.

    PubMed

    Wilson-Genderson, Maureen; Pruchno, Rachel

    2015-07-01

    Rates of functional limitations are consistently higher for women than for men, but it is not clear why. While some studies have examined individual risk factors, others have turned to broader social characteristics. We examined the effects of both individual and neighborhood characteristics associated with the functional limitations of older men and women. Multilevel structural equation models were developed using data from a random digit dial sample of 5,688 adults aged 50 to 74 years living in New Jersey. We found that greater numbers of fast-food restaurants, storefronts, and supermarkets was associated with more functional limitations of women, while greater numbers of fast-food restaurants was the only neighborhood characteristic associated with more functional limitations of men. Functional limitations of women, but not men, are affected by multiple neighborhood characteristics. This research reveals that specific neighborhood contextual characteristics, not just poverty, are associated with the health of community-dwelling adults. PMID:26543060

  8. Neighborhood Revitalization: Achieving the Tipping Point.

    ERIC Educational Resources Information Center

    Digh, Patricia

    2002-01-01

    Describes how, partnering with Fannie Mae, three institutions--Howard University, the University of Pennsylvania, and Jackson State University--have transformed their deteriorating neighborhoods into thriving communities. (EV)

  9. The neighborhood context of well-being.

    PubMed

    Sampson, Robert J

    2003-01-01

    Health-related problems are strongly associated with the social characteristics of communities and neighborhoods. We need to treat community contexts as important units of analysis in their own right, which in turn calls for new measurement strategies as well as theoretical frameworks that do not simply treat the neighborhood as a "trait" of the individual. Recent findings from the Project on Human Development in Chicago Neighborhoods support this thesis. Two major themes merit special attention: (1) the importance of collective efficacy for understanding health disparities in the modern city; and (2) the salience of spatial dynamics that go beyond the confines of local neighborhoods. Further efforts to explain the causes of variation in collective processes associated with healthy communities may provide innovative opportunities for preventive intervention. PMID:14563074

  10. Perceived Neighborhood Safety and Adolescent School Functioning

    PubMed Central

    Martin-Storey, Alexa; Crosnoe, Robert

    2014-01-01

    This study examined the association between adolescents’ perceptions of their neighborhoods’ safety and multiple elements of their functioning in school with data on 15 year olds from the NICHD Study of Early Child Care and Youth Development (n = 924). In general, perceived neighborhood safety was more strongly associated with aspects of schooling that were more psychosocial in nature (e.g., school attachment) than those that were more cognitive (e.g., test scores). Examination of neighborhood and family moderators of these associations revealed that perceived neighborhood safety was negatively associated with grades for youth from low-income families but was positively associated with school attachment for youth from such families when they lived in neighborhoods rated by observers as high in physical disorder. PMID:25045245

  11. The neighborhood context of adolescent mental health.

    PubMed

    Aneshensel, C S; Sucoff, C A

    1996-12-01

    Mental health disorders in adolescence are pervasive, often carry into adulthood, and appear to be inversely associated with social status. We examine how structural aspects of neighborhood context, specifically, socioeconomic stratification and racial/ethnic segregation, affect adolescent emotional well-being by shaping subjective perceptions of their neighborhoods. Using a community-based sample of 877 adolescents in Los Angeles County, we find that youth in low socioeconomic status (SES) neighborhoods perceive greater ambient hazards such as crime, violence, drug use, and graffiti than those in high SES neighborhoods. The perception of the neighborhood as dangerous, in turn, influences the mental health of adolescents: the more threatening the neighborhood, the more common the symptoms of depression, anxiety, oppositional defiant disorder, and conduct disorder. Social stability and, to a lesser extent, social cohesion, also emerge as contributors to adolescent disorder. This investigation demonstrates that research into the mental health of young people should consider the socioeconomic and demographic environments in which they live. PMID:8997886

  12. Prostate Cancer Severity Associations with Neighborhood Deprivation

    PubMed Central

    Zeigler-Johnson, Charnita M.; Tierney, Ann; Rebbeck, Timothy R.; Rundle, Andrew

    2011-01-01

    Background. The goal of this paper was to examine neighborhood deprivation and prostate cancer severity. Methods. We studied African American and Caucasian prostate cancer cases from the Pennsylvania State Cancer Registry. Census tract-level variables and deprivation scores were examined in relation to diagnosis stage, grade, and tumor aggressiveness. Results. We observed associations of low SES with high Gleason score among African Americans residing in neighborhoods with low educational attainment (OR = 1.34, 95% CI = 1.13–1.60), high poverty (OR = 1.39, 95% CI = 1.15–1.67), low car ownership (OR = 1.46, 95% CI = 1.20–1.78), and higher percentage of residents on public assistance (OR = 1.32, 95% = 1.08–1.62). The highest quartile of neighborhood deprivation was also associated with high Gleason score. For both Caucasians and African Americans, the highest quartile of neighborhood deprivation was associated with high Gleason score at diagnosis (OR = 1.34, 95% CI = 1.19–1.52; OR = 1.71, 95% CI = 1.21–2.40, resp.). Conclusion. Using a neighborhood deprivation index, we observed associations between high-grade prostate cancer and neighborhood deprivation in Caucasians and African-Americans. PMID:22111000

  13. Motion-based mechanisms of illusory contour synthesis.

    PubMed

    Anderson, B L; Barth, H C

    1999-10-01

    Neurophysiological studies and computational models of illusory contour formation have focused on contour orientation as the underlying determinant of illusory contour shape in both static and moving displays. Here, we report a class of motion-induced illusory contours that demonstrate the existence of novel mechanisms of illusory contour synthesis. In a series of experiments, we show that the velocity of contour terminations and the direction of motion of a partially occluded figure regulate the perceived shape and apparent movement of illusory contours formed from moving image sequences. These results demonstrate the existence of neural mechanisms that reconstruct occlusion relationships from both real and inferred image velocities, in contrast to the static geometric mechanisms that have been the focus of studies to date. PMID:10571236

  14. Do neighborhood attributes moderate the relationship between alcohol establishment density and crime?

    PubMed

    Erickson, Darin J; Carlin, Bradley P; Lenk, Kathleen M; Quick, Harrison S; Harwood, Eileen M; Toomey, Traci L

    2015-02-01

    Although numerous studies have found a positive association between the density of alcohol establishments and various types of crime, few have examined how neighborhood attributes (e.g., schools, parks) could moderate this association. We used data from Minneapolis, MN with neighborhood as the unit of analysis (n = 83). We examined eight types of crime (assault, rape, robbery, vandalism, nuisance crime, public alcohol consumption, driving while intoxicated, underage alcohol possession/consumption) and measured density as the total number of establishments per roadway mile. Neighborhood attributes assessed as potential moderators included non-alcohol businesses, schools, parks, religious institutions, neighborhood activism, neighborhood quality, and number of condemned houses. Using Bayesian techniques, we created a model for each crime outcome (accounting for spatial auto-correlation and controlling for relevant demographics) with an interaction term (moderator × density) to test each potential moderating effect. Few interaction terms were statistically significant. The presence of at least one college was the only neighborhood attribute that consistently moderated the density-crime association, with the presence of a college attenuating the association between the density and three types of crime (assaults, nuisance crime, and public consumption). However, caution should be used when interpreting the moderating effect of college presence because of the small number of colleges in our sample. The lack of moderating effects of neighborhood attributes, except for presence of a college, suggests that the addition of alcohol establishments to any neighborhood, regardless of its other attributes, could result in an increase in a wide range of crime. PMID:24337980

  15. Cross Sectional Association between Spatially Measured Walking Bouts and Neighborhood Walkability

    PubMed Central

    Hwang, Liang-Dar; Hurvitz, Philip M.; Duncan, Glen E.

    2016-01-01

    Walking is the most popular choice of aerobic physical activity to improve health among U.S. adults. Physical characteristics of the home neighborhood can facilitate or hinder walking. The purpose of this study was to quantify neighborhood walking, using objective methods and to examine the association between counts of walking bouts in the home neighborhood and neighborhood walkability. This was a cross-sectional study of 106 adults who wore accelerometers and GPS devices for two weeks. Walking was quantified within 1, 2, and 3 km Euclidean (straight-line) and network buffers around the geocoded home location. Walkability was estimated using a commercially available index. Walking bout counts increased with buffer size and were associated with walkability, regardless of buffer type or size (p < 0.001). Quantification of walking bouts within (and outside) of pre-defined neighborhood buffers of different sizes and types allowed for the specification of walking locations to better describe and elucidate walking behaviors. These data support the concept that neighborhood characteristics can influence walking among adults. PMID:27070633

  16. Social neighborhood environment and sports participation among Dutch adults: does sports location matter?

    PubMed

    Kramer, D; Stronks, K; Maas, J; Wingen, M; Kunst, A E

    2015-04-01

    Studies on the relation between the social neighborhood environment and sports participation have produced inconsistent results. Use of generic sports outcomes may have obscured associations only apparent for sports at certain locations. This study aims to assess the association between the social neighborhood environment and three location-specific sports outcomes. Repeated cross-sectional data on sports participation (any type of sports, sports at indoor sports clubs, sports at outdoor sports clubs, sports on streets) were obtained from 20 600 adults using the Dutch national health survey 2006-2009. Data on neighborhood social safety and social capital were obtained using the Dutch Housing Research 2006. Over 40% of Dutch adults participated in any type of sports. Indoor sports clubs were most popular. Multilevel logistic regression analyses revealed that neighborhood social safety was positively associated with sports at indoor sports clubs [odds ratio (OR) = 1.25, 95% confidence interval (CI) = 1.06-1.48), but not with the other sports outcomes. Contrary, neighborhood social capital was positively associated with sports on streets only (OR = 1.69, 95% CI = 1.17-2.44). The results suggest that a positive social neighborhood environment enhances sports participation, but that this impact depends on the location of the sports activity. This study highlights the importance of using location-specific sports outcomes when assessing environmental determinants. PMID:24506213

  17. Cross Sectional Association between Spatially Measured Walking Bouts and Neighborhood Walkability.

    PubMed

    Hwang, Liang-Dar; Hurvitz, Philip M; Duncan, Glen E

    2016-04-01

    Walking is the most popular choice of aerobic physical activity to improve health among U.S. adults. Physical characteristics of the home neighborhood can facilitate or hinder walking. The purpose of this study was to quantify neighborhood walking, using objective methods and to examine the association between counts of walking bouts in the home neighborhood and neighborhood walkability. This was a cross-sectional study of 106 adults who wore accelerometers and GPS devices for two weeks. Walking was quantified within 1, 2, and 3 km Euclidean (straight-line) and network buffers around the geocoded home location. Walkability was estimated using a commercially available index. Walking bout counts increased with buffer size and were associated with walkability, regardless of buffer type or size (p < 0.001). Quantification of walking bouts within (and outside) of pre-defined neighborhood buffers of different sizes and types allowed for the specification of walking locations to better describe and elucidate walking behaviors. These data support the concept that neighborhood characteristics can influence walking among adults. PMID:27070633

  18. Body Mass Index, Safety Hazards, and Neighborhood Attractiveness

    PubMed Central

    Lovasi, Gina S.; Bader, Michael D.M.; Quinn, James; Neckerman, Kathryn; Weiss, Christopher; Rundle, Andrew

    2012-01-01

    Background Neighborhood attractiveness and safety may encourage physical activity and help individuals maintain a healthy weight. However, these neighborhood characteristics may not be equally relevant to health across all settings and population subgroups. Purpose To evaluate whether potentially attractive neighborhood features are associated with lower BMI, whether safety hazards are associated with higher BMI, and whether environment–environment interactions are present such that associations for a particular characteristic are stronger in an otherwise supportive environment. Methods Survey data and measured height and weight were collected from a convenience sample of 13,102 adult New York City (NYC) residents in 2000–2002; data analyses were completed 2008–2012. Built-environment measures based on municipal GIS data sources were constructed within 1-km network buffers to assess walkable urban form (density, land-use mix, transit access); attractiveness (sidewalk cafés, landmark buildings, street trees, street cleanliness); and safety (homicide rate, pedestrian–auto collision and fatality prevalence). Generalized linear models with cluster-robust SEs controlled for individual and area-based sociodemographic characteristics. Results The presence of sidewalk cafés, density of landmark buildings, and density of street trees were associated with lower BMI, whereas the proportion of streets rated as clean was associated with higher BMI. Interactions were observed for sidewalk cafés with neighborhood poverty and walkability, for street-tree density with walkability, and for street cleanliness with safety. Safety hazard indicators were not independently associated with BMI. Conclusions Potentially attractive community and natural features were associated with lower BMI among adults in NYC, and there was some evidence of effect modification. PMID:22992355

  19. Neighborhood History as a Factor Shaping Syringe Distribution Networks Among Drug Users at a U.S. Syringe Exchange1

    PubMed Central

    Braine, Naomi; Acker, Caroline; Goldblatt, Cullen; Yi, Huso; Friedman, Samuel; DesJarlais, Don C.

    2008-01-01

    Throughout the US, high-visibility drug markets are concentrated in neighborhoods with few economic opportunities, while drug buyers/users are widely dispersed. A study of Pittsburgh Syringe Exchange participants provides data on travel between and network linkages across neighborhoods with different levels of drug activity. There are distinct racial patterns to syringe distribution activity within networks and across neighborhoods. Pittsburgh’s history suggests these patterns emerge from historical patterns of social and economic development. Study data demonstrate the ability of IDUs to form long term social ties across racial and geographic boundaries and use them to reduce the risk of HIV transmission. PMID:19578475

  20. Neighborhood Residents' Production of Order: The Effects of Collective Efficacy on Responses to Neighborhood Problems

    ERIC Educational Resources Information Center

    Wells, William; Schafer, Joseph A.; Varano, Sean P.; Bynum, Timothy S.

    2006-01-01

    Community policing agencies seek to engage communities to build working partnerships, solicit the input of neighborhood residents, and stimulate informal control of crime. A common barrier to these efforts is a lack of citizen participation. The purpose of this article is to assess the relationship between neighborhood-level variables and citizen…

  1. Bringing Promise to Washington, DC. The DC Promise Neighborhood Initiative. Program on Neighborhoods and Youth Development

    ERIC Educational Resources Information Center

    Comey, Jennifer; Scott, Molly M.; Popkin, Susan J.; Falkenburger, Elsa

    2012-01-01

    The U.S. Department of Education's Promise Neighborhood Initiative (DCPNI) is one of the Obama administration's major antipoverty initiatives and a core strategy of the White House's Neighborhood Revitalization Initiative. It is intended to improve educational outcomes by creating a continuum of school readiness, academic services, and family and…

  2. Perceived School and Neighborhood Safety, Neighborhood Violence and Academic Achievement in Urban School Children

    ERIC Educational Resources Information Center

    Milam, A. J.; Furr-Holden, C. D. M.; Leaf, P. J.

    2010-01-01

    Community and school violence continue to be a major public health problem, especially among urban children and adolescents. Little research has focused on the effect of school safety and neighborhood violence on academic performance. This study examines the effect of the school and neighborhood climate on academic achievement among a population…

  3. Neighborhood Economic Enterprises: An Analysis, Survey, and Guide to Resources in Starting Up Neighborhood Enterprises.

    ERIC Educational Resources Information Center

    Kotler, Neil G.

    This pamphlet provides information on the history of and current trends toward neighborhood economic enterprises and provides guidance for setting up such enterprises. A bibliography of books, articles, and newsletters that have information on how to start and sustain neighborhood businesses and cooperatives is provided. Also included is a list of…

  4. High effectiveness contour matching contact heat exchanger

    NASA Astrophysics Data System (ADS)

    Blakely, Robert L.; Roebelen, George J., Jr.; Davenport, Arthur K.

    1988-08-01

    There is a need in the art for a heat exchanger design having a flexible core providing contour matching capabilities, which compensates for manufacturing tolerance and distortion buildups, and which accordingly furnishes a relatively uniform thermal contact conductance between the core and external heat sources under essentially all operating conditions. The core of the heat exchanger comprises a top plate and a bottom plate, each having alternate rows of pins attached. Each of the pins fits into corresponding tight-fitting recesses in the opposite plate.

  5. Body contouring following massive weight loss

    PubMed Central

    Langer, Vijay; Singh, Amitabh; Aly, Al S.; Cram, Albert E.

    2011-01-01

    Obesity is a global disease with epidemic proportions. Bariatric surgery or modified lifestyles go a long way in mitigating the vast weight gain. Patients following these interventions usually undergo massive weight loss. This results in redundant tissues in various parts of the body. Loose skin causes increased morbidity and psychological trauma. This demands various body contouring procedures that are usually excisional. These procedures are complex and part of a painstaking process that needs a committed patient and an industrious plastic surgeon. As complications in these patients can be quite frequent, both the patient and the surgeon need to be aware and willing to deal with them. PMID:21713202

  6. Contour dynamics model for electric discharges.

    PubMed

    Arrayás, M; Fontelos, M A; Jiménez, C

    2010-03-01

    We present an effective contour model for electrical discharges deduced as the asymptotic limit of the minimal streamer model for the propagation of electric discharges, in the limit of small electron diffusion. The incorporation of curvature effects to the velocity propagation and not to the boundary conditions is a feature and makes it different from the classical Laplacian growth models. The dispersion relation for a nonplanar two-dimensional discharge is calculated. The development and propagation of fingerlike patterns are studied and their main features quantified. PMID:20365808

  7. High effectiveness contour matching contact heat exchanger

    NASA Technical Reports Server (NTRS)

    Blakely, Robert L. (Inventor); Roebelen, George J., Jr. (Inventor); Davenport, Arthur K. (Inventor)

    1988-01-01

    There is a need in the art for a heat exchanger design having a flexible core providing contour matching capabilities, which compensates for manufacturing tolerance and distortion buildups, and which accordingly furnishes a relatively uniform thermal contact conductance between the core and external heat sources under essentially all operating conditions. The core of the heat exchanger comprises a top plate and a bottom plate, each having alternate rows of pins attached. Each of the pins fits into corresponding tight-fitting recesses in the opposite plate.

  8. Shear-strain contours from moire interferometry

    NASA Technical Reports Server (NTRS)

    Post, D.; Czarnek, R.; Joh, D.

    1985-01-01

    The development of whole-field contour maps of shear strains gamma (xy), derived from displacement fields obtained by moire interferometry with 2400 lines/mm, is described. The use of mechanical differentiation to obtain cross-derivatives of displacements and the use of graphical additive moire to sum the cross-derivatives are explained. Quantitative analysis in the small-strain domain is possible because of the high sensitivity of moire interferometry. The applicability of this technique is shown by the testing of a short epoxy beam under three-point bending.

  9. Topologically correct reconstruction of tortuous contour forests

    PubMed Central

    Edwards, John; Bajaj, Chandrajit

    2011-01-01

    Motivated by the need for correct and robust 3D models of neuronal processes, we present a method for reconstruction of spatially realistic and topologically correct models from planar cross sections of multiple objects. Previous work in 3D reconstruction from serial contours has focused on reconstructing one object at a time, potentially producing inter-object intersections between slices. We have developed a robust algorithm that removes these intersections using a geometric approach. Our method not only removes intersections but can guarantee a given minimum separation distance between objects. This paper describes the algorithm for geometric adjustment, proves correctness, and presents several results of our high-fidelity modeling. PMID:22003256

  10. Assessment of a Newark neighborhood: process and outcomes.

    PubMed

    Elliot, N L; Quinless, F W; Parietti, E S

    2000-01-01

    In 1996, the members of the St. Columba Collaboration conducted a grassroots neighborhood assessment of a Hispanic area in Newark, New Jersey. This assessment was undertaken during an era of significant political and policy change in New Jersey. As a community-driven and implemented effort, the processes, methods, and outcomes of this assessment provide lessons on community activism, political awareness, and strategic planning. Quantitative surveys were distributed to local residents as well as users of the various services provided through Collaboration programs. Ten qualitative focus groups were held among various Collaboration groups. A total of 471 surveys were returned from a door-to-door distribution and 295 surveys were returned from users of Collaboration programs. Findings from both the quantitative and qualitative components were surprisingly similar. It was striking to note that youth violence, domestic violence, crime, and lack of job skills surpassed poor housing and chronic health problems, including HIV/AIDS and drug and alcohol addiction, as the most noted neighborhood problems. Overwhelmingly, social, welfare, and environmental issues were identified as priority items in a neighborhood marked by extreme poverty, poor childhood immunization rates, high HIV/AIDS rates, and high incidence of childhood asthma. Focus group findings revealed that stressful daily life events and circumstances far overshadowed health and wellness concerns. Recommendations emanating from the St. Columba Neighborhood needs assessment included: (a) establishment of principled partnerships between the Collaboration and other regional entities to extend capacity to design and implement solutions (e.g., partnerships with other higher education institutions, health care agencies); (b) development of strategic planning processes and procedures within the Collaboration; (c) establishment of collaborative partnerships with other Hispanic community-based organizations for political

  11. Partnering with Youth to Map Their Neighborhood Environments: A Multi-Layered GIS Approach

    PubMed Central

    Topmiller, Michael; Jacquez, Farrah; Vissman, Aaron T.; Raleigh, Kevin; Miller-Francis, Jenni

    2014-01-01

    Mapping approaches offer great potential for community-based participatory researchers interested in displaying youth perceptions and advocating for change. We describe a multi-layered approach for gaining local knowledge of neighborhood environments that engages youth as co-researchers and active knowledge producers. By integrating geographic information systems (GIS) with environmental audits, an interactive focus group, and sketch mapping, the approach provides a place-based understanding of physical activity resources from the situated experience of youth. Youth report safety and a lack of recreational resources as inhibiting physical activity. Maps reflecting youth perceptions aid policy-makers in making place-based improvements for youth neighborhood environments. PMID:25423245

  12. Collinear facilitation and contour integration in autism: evidence for atypical visual integration

    PubMed Central

    Jachim, Stephen; Warren, Paul A.; McLoughlin, Niall; Gowen, Emma

    2015-01-01

    Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social interaction, atypical communication and a restricted repertoire of interests and activities. Altered sensory and perceptual experiences are also common, and a notable perceptual difference between individuals with ASD and controls is their superior performance in visual tasks where it may be beneficial to ignore global context. This superiority may be the result of atypical integrative processing. To explore this claim we investigated visual integration in adults with ASD (diagnosed with Asperger’s Syndrome) using two psychophysical tasks thought to rely on integrative processing—collinear facilitation and contour integration. We measured collinear facilitation at different flanker orientation offsets and contour integration for both open and closed contours. Our results indicate that compared to matched controls, ASD participants show (i) reduced collinear facilitation, despite equivalent performance without flankers; and (ii) less benefit from closed contours in contour integration. These results indicate weaker visuospatial integration in adults with ASD and suggest that further studies using these types of paradigms would provide knowledge on how contextual processing is altered in ASD. PMID:25805985

  13. Automatic segmentation of vertebral contours from CT images using fuzzy corners.

    PubMed

    Athertya, Jiyo S; Saravana Kumar, G

    2016-05-01

    Automatic segmentation of bone in computed tomography (CT) images is critical for the implementation of computer-assisted diagnosis which has increasing potential in the evaluation of various spine disorders. Of the many techniques available for delineating the region of interest (ROI), active contour methods (ACM) are well-established techniques that are used to segment medical images. The initialization for these methods is either through manual intervention or by applying a global threshold, thus making them semi-automatic in nature. The paper presents a methodology for automatic contour initialization in ACM and demonstrates the applicability of the method for medical image segmentation from spinal CT images. Initially, a set of feature markers from the image is extracted to construct an initial contour for the ACM. A fuzzified corner metric, based on image intensity, is proposed to identify the feature markers to be enclosed by the contour. A concave hull based on α shape, is constructed using these fuzzy corners to give the initial contour. The proposed method was evaluated against conventional feature detectors and other initialization methods. The results show the method׳s robust performance in the presence of simulated Gaussian noise levels. The method enables the ACM to efficiently converge to the ground truth segmentation. The reference standard for comparison was the annotated images from a radiologist, and the Dice coefficient and Hausdorff distance measures were used to evaluate the segmentation. PMID:27017068

  14. Applying successful near mission operations approaches and refining for contour mission operations

    NASA Astrophysics Data System (ADS)

    Holdridge, Mark E.

    2003-01-01

    On February 17, 1996, the first NASA Discovery Class Mission to launch, the Near Earth Asteroid Rendezvous (NEAR) spacecraft, began its journey to the asteroid Eros. NEAR is the first planetary spacecraft to be designed and operated by the Johns Hopkins University Applied Physics Laboratory (JHU/APL). In July 2002, the comet nucleus tour (CONTOUR) spacecraft, the second planetary spacecraft to be built and operated at JHUAPL and the 6th in the series of NASA Discovery Class Missions, will be launched. Both NEAR and CONTOUR share ambitious "Faster, Better, Cheaper" goals. Furthermore, with both missions being developed and operated at the same institution, a unique opportunity exists to refine CONTOUR designs and operational practices based on 5 years of NEAR operational experience. This paper provides an overview of designs and operational practices implemented by JHU/APL to safely and effectively conduct the NEAR mission. This paper discusses how these will be applied to the CONTOUR mission and what improvements are planned. It also discusses the unique challenges CONTOUR possesses for operating a 4 year mission with widely varying operations activity levels at low cost.

  15. Collinear facilitation and contour integration in autism: evidence for atypical visual integration.

    PubMed

    Jachim, Stephen; Warren, Paul A; McLoughlin, Niall; Gowen, Emma

    2015-01-01

    Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social interaction, atypical communication and a restricted repertoire of interests and activities. Altered sensory and perceptual experiences are also common, and a notable perceptual difference between individuals with ASD and controls is their superior performance in visual tasks where it may be beneficial to ignore global context. This superiority may be the result of atypical integrative processing. To explore this claim we investigated visual integration in adults with ASD (diagnosed with Asperger's Syndrome) using two psychophysical tasks thought to rely on integrative processing-collinear facilitation and contour integration. We measured collinear facilitation at different flanker orientation offsets and contour integration for both open and closed contours. Our results indicate that compared to matched controls, ASD participants show (i) reduced collinear facilitation, despite equivalent performance without flankers; and (ii) less benefit from closed contours in contour integration. These results indicate weaker visuospatial integration in adults with ASD and suggest that further studies using these types of paradigms would provide knowledge on how contextual processing is altered in ASD. PMID:25805985

  16. Response priming evidence for feedforward processing of snake contours but not of ladder contours and textures.

    PubMed

    Schmidt, Filipp; Vancleef, Kathleen

    2016-09-01

    In contour integration, increased difficulty in detection and shape discrimination of a chain of parallel elements (a ladder contour) compared to collinear elements (a snake contour) suggests more extensive processing of ladders than of snakes. In addition, conceptual similarities between ladders and textures - which also involve grouping of parallel elements - raises the question whether ladder and texture processing requires feedback from higher visual areas while snakes are processed in a fast feedforward sweep. We tested this in a response priming paradigm, where participants responded as quickly and accurately as possible to the orientation of a diagonal contour in a Gabor array (target). The diagonal was defined either by a snake, ladder, texture, or a continuous line. The target was preceded with varying stimulus onset asynchrony (SOA) by a prime that was either a snake, ladder, or texture, and was consistent or inconsistent to the response demands of the target. Resulting priming effects clearly distinguished between processing of snakes, ladders, and textures. Effects generally increased with SOA but were stronger for snakes and textures compared to ladders. Importantly, only priming effects for snakes were fully present already in the fastest response times, in accordance with a simple feedforward processing model. We conclude that snakes, ladders, and textures do not share similar processing characteristics, with snakes exhibiting a pronounced processing advantage. PMID:25771400

  17. CONTOUR; a modification of G.I. Evenden's general purpose contouring program

    USGS Publications Warehouse

    Godson, R.H.; Webring, M.W.

    1982-01-01

    A contouring program written for the DEC-10 computer (Evenden, 1975) has been modified and enhanced to operate on a Honeywell Multics 68/80 computer. The program uses a device independent plotting system (Wahl, 1977) so that output can be directed to any of several plotting devices by simply specifying one input variable.

  18. NEIGHBORHOOD IMMIGRATION AND NATIVE OUT-MIGRATION

    PubMed Central

    Crowder, Kyle; Hall, Matthew; Tolnay, Stewart E.

    2011-01-01

    This study combines data from the Panel Study of Income Dynamics with data from four censuses to examine the effects of foreign-born populations in the immediate neighborhood of residence and surrounding neighborhoods on the residential mobility decisions of native-born black and white householders. We find that the likelihood of out-mobility for native householders is significantly and positively associated with the relative size of, and increases in, the immigrant population in the neighborhood. Consistent with theoretical arguments related to the distance dependence of mobility, large concentrations of immigrants in surrounding areas reduce native out-mobility, presumably by reducing the attractiveness of the most likely mobility destinations. A sizable share of local immigration effects can be explained by the mobility-related characteristics of native-born individuals living in immigrant-populated areas, but the racial composition of the neighborhood (for native whites) and local housing market conditions (for native blacks) also are important mediating factors. The implications of these patterns for processes of neighborhood change and broader patterns of residential segregation are discussed. PMID:21731082

  19. Neighborhood Diversity, Metropolitan Constraints, and Household Migration

    PubMed Central

    Crowder, Kyle; Pais, Jeremy; South, Scott J.

    2012-01-01

    Focusing on micro-level processes of residential segregation, this analysis combines data from the Panel Study of Income Dynamics with contextual information from three censuses and several other sources to examine patterns of residential mobility between neighborhoods populated by different combinations of racial and ethnic groups. We find that despite the emergence of multiethnic neighborhoods, stratified mobility dynamics continue to dominate, with relatively few black or white households moving into neighborhoods that could be considered multiethnic. However, we also find that the tendency for white and black households to move between neighborhoods dominated by their own group varies significantly across metropolitan areas. Black and white households’ mobility into more integrated neighborhoods is shaped substantially by demographic, economic, political, and spatial features of the broader metropolitan area. Metropolitan-area racial composition, the stock of new housing, residential separation of black and white households, poverty rates, and functional specialization emerge as particularly important predictors. These macro-level effects reflect opportunities for intergroup residential contact as well as structural forces that maintain residential segregation. PMID:22753955

  20. Neighborhood Energy/Economic Development project

    SciTech Connect

    Not Available

    1991-12-31

    Energy costs impact low income communities more than anyone else. Low income residents pay a larger percentage of their incomes for energy costs. In addition, they generally have far less discretionary energy use to eliminate in response to increasing energy prices. Furthermore, with less discretionary income, home energy efficiency improvements are often too expensive. Small neighborhood businesses are in the same situation. Improved efficiency in the use of energy can improve this situation by reducing energy costs for residents and local businesses. More importantly, energy management programs can increase the demand for local goods and services and lead to the creation of new job training and employment opportunities. In this way, neighborhood based energy efficiency programs can support community economic development. The present project, undertaken with the support of the Urban Consortium Energy Task Force, was intended to serve as a demonstration of energy/economic programming at the neighborhood level. The San Francisco Neighborhood Energy/Economic Development (NEED) project was designed to be a visible demonstration of bringing the economic development benefits of energy management home to low-income community members who need it most. To begin, a Community Advisory Committee was established to guide the design of the programs to best meet needs of the community. Subsequently three neighborhood energy/economic development programs were developed: The small business energy assistance program; The youth training and weatherization program; and, The energy review of proposed housing development projects.

  1. Memory for pure tone sequences without contour.

    PubMed

    Lefebvre, Christine; Jolicœur, Pierre

    2016-06-01

    We presented pure tones interspersed with white noise sounds to disrupt contour perception in an acoustic short-term memory (ASTM) experiment during which we recorded the electroencephalogram. The memory set consisted of seven stimuli, 0, 1, 2, 3, or 4 of which were to-be-remembered tones. We estimated each participant׳s capacity, K, for each set size and measured the amplitude of the SAN (sustained anterior negativity, an ERP related to acoustic short-term memory). We correlated their K slopes with their SAN amplitude slopes as a function of set size, and found a significant link between performance and the SAN: a larger increase in SAN amplitude was linked with a larger number of stimuli maintained in ASTM. The SAN decreased in amplitude in the later portion of the silent retention interval, but the correlation between the SAN and capacity remained strong. These results show the SAN is not an index of contour but rather an index of the maintenance of individual objects in STM. This article is part of a Special Issue entitled SI: Auditory working memory. PMID:26903419

  2. Associative and orthographic neighborhood density effects in normal aging and Alzheimer's disease.

    PubMed

    Duñabeitia, Jon Andoni; Marín, Alejandro; Carreiras, Manuel

    2009-11-01

    A group of patients with Alzheimer's disease and a group of healthy elderly controls were tested with a lexical-decision task that included words with dense or sparse orthographic and associative neighborhoods to investigate whether there is automatic orthographic and semantic activation of related representations in these populations similar to that found with younger samples. Although some studies support the idea of deteriorated connections in semantic networks in Alzheimer's disease, other studies propose that the automatic spread of activation at lexicosemantic levels remains intact and that intergroup differences are a consequence of impaired retrieval or attentional deficits. In this study, participants responded to words with dense orthographic and associative neighborhoods faster than they did to words with sparse neighborhoods, providing evidence in favor of a preserved automatic spread of activation through intact orthographic and semantic representations. Furthermore, no differences were found between the two groups regarding the magnitude of the effects, although control participants responded significantly faster than patients. PMID:19899834

  3. Neighborhood disorder and screen time among 10-16 year old Canadian youth: A cross-sectional study

    PubMed Central

    2012-01-01

    Background Screen time activities (e.g., television, computers, video games) have been linked to several negative health outcomes among young people. In order to develop evidence-based interventions to reduce screen time, the factors that influence the behavior need to be better understood. High neighborhood disorder, which may encourage young people to stay indoors where screen time activities are readily available, is one potential factor to consider. Methods Results are based on 15,917 youth in grades 6-10 (aged 10-16 years old) who participated in the Canadian 2009/10 Health Behaviour in School-aged Children Survey (HBSC). Total hours per week of television, video games, and computer use were reported by the participating students in the HBSC student questionnaire. Ten items of neighborhood disorder including safety, neighbors taking advantage, drugs/drinking in public, ethnic tensions, gangs, crime, conditions of buildings/grounds, abandoned buildings, litter, and graffiti were measured using the HBSC student questionnaire, the HBSC administrator questionnaire, and Geographic Information Systems. Based upon these 10 items, social and physical neighborhood disorder variables were derived using principal component analysis. Multivariate multilevel logistic regression analyses were used to examine the relationship between social and physical neighborhood disorder and individual screen time variables. Results High (top quartile) social neighborhood disorder was associated with approximately 35-45% increased risk of high (top quartile) television, computer, and video game use. Physical neighborhood disorder was not associated with screen time activities after adjusting for social neighborhood disorder. However, high social and physical neighborhood disorder combined was associated with approximately 40-60% increased likelihood of high television, computer, and video game use. Conclusion High neighborhood disorder is one environmental factor that may be important

  4. Neighborhood perceptions and health-related outcomes among Latinos with diabetes from a rural agricultural community.

    PubMed

    Moreno, Gerardo; Morales, Leo S; Nuñez de Jaimes, Fatima; Tseng, Chi-Hong; Isiordia, Marilu; Noguera, Christine; Mangione, Carol M

    2014-12-01

    Little is known about how neighborhood perceptions are related to diabetes outcomes among Latinos living in rural agricultural communities. Our objective was to examine the association between perceived neighborhood problems and diabetes outcomes. This is a cross-sectional survey study with medical record reviews of a random sample of 250 adult Latinos with type 2 diabetes. The predictor was a rating of patient ratings of neighborhood problems (crime, trash and litter, lighting at night, and access to exercise facilities, transportation, and supermarkets). The primary outcomes were the control of three intermediate outcomes [LDL-cholesterol (LDL-c) < 100 mg/dl, AlC < 9.0 %, and blood pressure (BP) < 140/80 mmHg], and body mass index (BMI) < 30 kg/m(2). Secondary outcomes were participation in self-care activities (physical activity, healthy eating, medication adherence, foot checks, and glucose checks). We used regression analysis and adjusted for age, gender, education, income, years with diabetes, insulin use, depressive symptoms, and co-morbidities. Forty-eight percent of patients perceived at least one neighborhood problem and out of the six problem areas, crime was most commonly perceived as a problem. Perception of neighborhood problems was independently associated with not having a BP < 140/80 [Adjusted odds ratio (AOR) = 0.45; 95 % CI 0.22, 0.92], and BMI < 30 (AOR = 0.43; 95 % CI 0.24, 0.77), after controlling for covariates. Receipt of recommended processes of care was not associated with perception of neighborhood. Perception of neighborhood problems among low-income rural Latinos with diabetes was independently associated with a higher BMI and BP. PMID:24599665

  5. Neighborhood Perceptions and Health-Related Outcomes among Latinos with Diabetes from a Rural Agricultural Community

    PubMed Central

    Moreno, Gerardo; Morales, Leo S.; de Jaimes, Fatima Nunez; Tseng, Chi-Hong; Isiordia, Marilu; Noguera, Christine; Mangione, Carol M.

    2014-01-01

    Little is known about how neighborhood perceptions are related to diabetes outcomes among Latinos living in rural agricultural communities. Our objective was to examine the association between perceived neighborhood problems and diabetes outcomes. This is a cross-sectional survey study with medical record reviews of a random sample of 250 adult Latinos with type 2 diabetes. The predictor was a rating of patient ratings of neighborhood problems (crime, trash and litter, lighting at night, and access to exercise facilities, transportation, and supermarkets). The primary outcomes were the control of three intermediate outcomes (LDL-c <100 mg/dl, AlC < 9.0%, and blood pressure (BP) < 140/80 mmHg), and body mass index (BMI) < 30 kg/m2. Secondary outcomes were participation in self-care activities (physical activity, healthy eating, medication adherence, foot checks, and glucose checks). We used regression analysis and adjusted for age, gender, education, income, years with diabetes, insulin use, depressive symptoms, and co-morbidities. Forty-eight percent of patients perceived at least one neighborhood problem and out of the six problem areas, crime was most commonly perceived as a problem. Perception of neighborhood problems was independently associated with not having a BP < 140/80 (Adjusted odds ratio [AOR]= 0.45; 95% CI: 0.22, 0.92), and BMI < 30 (AOR=0.43; 95% CI: 0.24, 0.77), after controlling for covariates. Receipt of recommended processes of care was not associated with perception of neighborhood. Perception of neighborhood problems among low-income rural Latinos with diabetes was independently associated with a higher BMI and BP. PMID:24599665

  6. Development of neural basis for chinese orthographic neighborhood size effect.

    PubMed

    Zhao, Jing; Li, Qing-Lin; Ding, Guo-Sheng; Bi, Hong-Yan

    2016-02-01

    The brain activity of orthographic neighborhood size (N size) effect in Chinese character naming has been studied in adults, meanwhile behavioral studies have revealed a developmental trend of Chinese N-size effect in developing readers. However, it is unclear whether and how the neural mechanism of N-size effect changes in Chinese children along with development. Here we address this issue using functional magnetic resonance imaging. Forty-four students from the 3(rd) , 5(th) , and 7(th) grades were scanned during silent naming of Chinese characters. After scanning, all participants took part in an overt naming test outside the scanner, and results of the naming task showed that the 3(rd) graders named characters from large neighborhoods faster than those from small neighborhoods, revealing a facilitatory N-size effect; the 5(th) graders showed null N-size effect while the 7(th) graders showed an inhibitory N-size effect. Neuroimaging results revealed that only the 3(rd) graders exhibited a significant N-size effect in the left middle occipital activity, with greater activation for large N-size characters. Results of 5(th) and 7(th) graders showed significant N-size effects in the left middle frontal gyrus, in which 5(th) graders induced greater activation in large N-size condition than in small N-size condition, while 7(th) graders exhibited an opposite effect which was similar to the adult pattern reported in a previous study. The current findings suggested the transition from broadly tuned to finely tuned orthographic representation with reading development, and the inhibition from neighbors' phonology for higher graders. Hum Brain Mapp 37:632-647, 2016. © 2015 Wiley Periodicals, Inc. PMID:26777875

  7. How to Develop the Medical Neighborhood.

    PubMed

    Feuerstein, Joseph D; Sheppard, Victoria; Cheifetz, Adam S; Ariyabuddhiphongs, Kim

    2016-09-01

    Significant attention has been directed towards developing the medical home and improving the patient experience. The medical home is targeted towards optimizing the quality of patient care while also reducing overall costs. An extension of the medical home is the concept of a medical neighborhood. The medical neighborhood utilizes the success of the medical home and incorporates it into the coordination of care between primary care physician and specialists. In order to create an ideal system, though, the framework for making referrals, ordering tests prior to referrals, documentation and communication of recommendations must be addressed a priori. In this perspective we discuss the necessary steps to implement a medical neighborhood for patients with chronic medical conditions and the use of medical technology to facilitate this process. PMID:27447470

  8. Noninvasive and minimally invasive techniques in body contouring.

    PubMed

    Afrooz, Paul N; Pozner, Jason N; DiBernardo, Barry E

    2014-10-01

    Major surgical body contouring procedures have several inherent drawbacks, including hospitalization, anesthetic use, pain, swelling, and prolonged recovery. It is for these reasons that body contouring through noninvasive and minimally invasive methods has become one of the most alluring areas in aesthetic surgery. Patient expectations and demands have driven the field toward safer, less-invasive procedures with less discomfort, fewer complications, and a shorter recovery. In this article, the current minimally invasive and noninvasive modalities for body contouring are reviewed. PMID:25283463

  9. Perceived School and Neighborhood Safety, Neighborhood Violence and Academic Achievement in Urban School Children.

    PubMed

    Aj, Milam; Cdm, Furr-Holden; Pj, Leaf

    2010-12-01

    Community and school violence continue to be a major public health problem, especially among urban children and adolescents. Little research has focused on the effect of school safety and neighborhood violence on academic performance. This study examines the effect of the school and neighborhood climate on academic achievement among a population of 3(rd)-5(th) grade students in an urban public school system. Community and school safety were assessed using the School Climate Survey, an annual city-wide assessment of student's perception of school and community safety. Community violence was measured using the Neighborhood Inventory for Environmental Typology, an objective observational assessment of neighborhood characteristics. Academic achievement was measured using the Maryland State Assessment (MSA), a standardized exam given to all Maryland 3(rd)-8(th) graders. School Climate Data and MSA data were aggregated by school and grade. Objective assessments of neighborhood environment and students' self-reported school and neighborhood safety were both strongly associated with academic performance. Increasing neighborhood violence was associated with statistically significant decreases from 4.2%-8.7% in math and reading achievement; increasing perceived safety was associated with significant increases in achievement from 16%-22%. These preliminary findings highlight the adverse impact of perceived safety and community violence exposure on primary school children's academic performance. PMID:21197388

  10. The Effect of Neighborhood Recorded Crime on Fear: Does Neighborhood Social Context Matter?

    PubMed

    Pearson, Amber L; Breetzke, Gregory; Ivory, Vivienne

    2015-09-01

    A number of individual and neighborhood-level factors may influence the relationship between recorded crime in one's neighborhood and fear of crime. Understanding these factors may assist in reducing fear, which has been associated with poorer physical and mental health. The aim of this study was to evaluate whether the effect of recorded crime rates on fear differs based on the neighborhood social context (social fragmentation) using hierarchical regression modelling, with separate analyses by crime type. Recorded crimes (2008-2010) and national (New Zealand) survey data were used. Higher crime in a neighborhood was associated with higher fear of crime, with only small effect size differences in feelings of fear by recorded type of crime. However, when stratified, the associations between violent and drug/alcohol crimes and fear of crime were larger for those living in highly fragmented neighborhoods compared with less fragmented neighborhoods. Efforts to alleviate fear of crime should focus on the broader neighborhood social context in which these feelings are espoused. PMID:26163273

  11. Measuring the neighborhood environment: associations with young girls' energy intake and expenditure in a cross-sectional study

    PubMed Central

    2010-01-01

    Background Neighborhood environments affect children's health outcomes. Observational methods used to assess neighborhoods can be categorized as indirect, intermediate, or direct. Direct methods, involving in-person audits of the neighborhoods conducted by trained observers, are recognized as an accurate representation of current neighborhood conditions. The authors investigated the associations of various neighborhood characteristics with young girls' diet and physical activity. Methods This study is based on a subset of participants in the Cohort Study of Young Girls' Nutrition, Environment and Transitions (CYGNET). In-person street audits were conducted within 215 girls' residential neighborhoods using a modified St. Louis Audit Tool. From the street audit data, exploratory factor analysis revealed five neighborhood scales: "mixed residential and commercial," "food and retail," "recreation," "walkability," and "physical disorder." A Neighborhood Deprivation Index was also derived from census data. The authors investigated if the five neighborhood scales and the Neighborhood Deprivation Index were associated with quartiles of total energy intake and expenditure (metabolic equivalent (MET) hours/week) at baseline, and whether any of these associations were modified by race/ethnicity. Results After adjustment for demographic characteristics, there was an inverse association between prevalence of "food and retail" destinations and total energy intake (for a one quartile increase, OR = 0.84, 95% CI 0.74, 0.96). Positive associations were also observed between the "recreation" and "walkability" scales with physical activity among Hispanic/Latina girls (for a one quartile increase in MET, OR = 1.94, 95% CI 1.31, 2.88 for recreation; OR = 1.71, 95% CI 1.11, 2.63 for walkability). Among African-American girls, there was an inverse association between "physical disorder" and physical activity (OR = 0.31, 95% CI 0.12, 0.80). Conclusions These results suggest that

  12. Effects of Spatial Frequency Similarity and Dissimilarity on Contour Integration

    PubMed Central

    Persike, Malte; Meinhardt, Günter

    2015-01-01

    We examined the effects of spatial frequency similarity and dissimilarity on human contour integration under various conditions of uncertainty. Participants performed a temporal 2AFC contour detection task. Spatial frequency jitter up to 3.0 octaves was applied either to background elements, or to contour and background elements, or to none of both. Results converge on four major findings. (1) Contours defined by spatial frequency similarity alone are only scarcely visible, suggesting the absence of specialized cortical routines for shape detection based on spatial frequency similarity. (2) When orientation collinearity and spatial frequency similarity are combined along a contour, performance amplifies far beyond probability summation when compared to the fully heterogenous condition but only to a margin compatible with probability summation when compared to the fully homogenous case. (3) Psychometric functions are steeper but not shifted for homogenous contours in heterogenous backgrounds indicating an advantageous signal-to-noise ratio. The additional similarity cue therefore not so much improves contour detection performance but primarily reduces observer uncertainty about whether a potential candidate is a contour or just a false positive. (4) Contour integration is a broadband mechanism which is only moderately impaired by spatial frequency dissimilarity. PMID:26057620

  13. Contour identification with pitch and loudness cues using cochlear implants.

    PubMed

    Luo, Xin; Masterson, Megan E; Wu, Ching-Chih

    2014-01-01

    Different from speech, pitch and loudness cues may or may not co-vary in music. Cochlear implant (CI) users with poor pitch perception may use loudness contour cues more than normal-hearing (NH) listeners. Contour identification was tested in CI users and NH listeners; the five-note contours contained either pitch cues alone, loudness cues alone, or both. Results showed that NH listeners' contour identification was better with pitch cues than with loudness cues; CI users performed similarly with either cues. When pitch and loudness cues were co-varied, CI performance significantly improved, suggesting that CI users were able to integrate the two cues. PMID:24437857

  14. Is neighborhood green space associated with a lower risk of type 2 diabetes? Evidence from 267,072 Australians.

    PubMed

    Astell-Burt, Thomas; Feng, Xiaoqi; Kolt, Gregory S

    2014-01-01

    OBJECTIVE Lifestyle interventions for type 2 diabetes mellitus (T2DM) are best positioned for success if participants live in supportive neighborhood environments. Deprived neighborhoods increase T2DM risk. Parks and other "green spaces" promote active lifestyles and therefore may reduce T2DM risk. We investigated association between neighborhood green space and the risk of T2DM in a large group of adult Australians. RESEARCH DESIGN AND METHODS Multilevel logit regression was used to fit associations between medically diagnosed T2DM and green space exposure among 267,072 participants in the 45 and Up Study. Green space data were obtained from the Australian Bureau of Statistics, and exposure was calculated using a 1-km buffer from a participant's place of residence. Odds ratios (ORs) were controlled for measures of demographic, cultural, health, diet, active lifestyles, socioeconomic status, and neighborhood circumstances. RESULTS The rate of T2DM was 9.1% among participants in neighborhoods with 0-20% green space, but this rate dropped to approximately 8% for participants with over 40% green space within their residential neighborhoods. The risk of T2DM was significantly lower in greener neighborhoods, controlling for demographic and cultural factors, especially among participants residing in neighborhoods with 41-60% green space land use (OR 0.87; 95% CI 0.83-0.92). This association was consistent after controlling for other explanatory variables and did not vary according to neighborhood circumstances. CONCLUSIONS People in greener surroundings have a lower risk of T2DM. Planning, promoting, and maintaining local green spaces is important in multisector initiatives for addressing the T2DM epidemic. PMID:24026544

  15. Neighborhood and weight-related health behaviors in the Look AHEAD (Action for Health in Diabetes) Study

    PubMed Central

    2010-01-01

    Background Previous studies have shown that neighborhood factors are associated with obesity, but few studies have evaluated the association with weight control behaviors. This study aims to conduct a multi-level analysis to examine the relationship between neighborhood SES and weight-related health behaviors. Methods In this ancillary study to Look AHEAD (Action for Health in Diabetes) a trial of long-term weight loss among individuals with type 2 diabetes, individual-level data on 1219 participants from 4 clinic sites at baseline were linked to neighborhood-level data at the tract level from the 2000 US Census and other databases. Neighborhood variables included SES (% living below the federal poverty level) and the availability of food stores, convenience stores, and restaurants. Dependent variables included BMI, eating patterns, weight control behaviors and resource use related to food and physical activity. Multi-level models were used to account for individual-level SES and potential confounders. Results The availability of restaurants was related to several eating and weight control behaviors. Compared to their counterparts in neighborhoods with fewer restaurants, participants in neighborhoods with more restaurants were more likely to eat breakfast (prevalence Ratio [PR] 1.29 95% CI: 1.01-1.62) and lunch (PR = 1.19, 1.04-1.36) at non-fast food restaurants. They were less likely to be attempting weight loss (OR = 0.93, 0.89-0.97) but more likely to engage in weight control behaviors for food and physical activity, respectively, than those who lived in neighborhoods with fewer restaurants. In contrast, neighborhood SES had little association with weight control behaviors. Conclusion In this selected group of weight loss trial participants, restaurant availability was associated with some weight control practices, but neighborhood SES was not. Future studies should give attention to other populations and to evaluating various aspects of the physical and social

  16. Body contouring surgery for military personnel following massive weight loss.

    PubMed

    Chong, S J; Kok, Y O; Foo, C L

    2011-12-01

    The burgeoning global obesity epidemic extends to the military service, where 6-53% of military personnel are overweight. Obese military personnel who adhere to a strict training and diet regime may potentially achieve and maintain significant weight loss. They may however face physical problems such as excess skin folds causing discomfort, difficulty in uniform fitting, personal hygiene, interference with full physical activities and psychological issues such as body image dissatisfaction, low self esteem and difficulty in social acceptance. We present a case report of a highly motivated military conscript who achieved and maintained significant weight loss but had physical defects following Massive Weight Loss. Body contouring surgery was successfully utilised to correct his physical defects and allowed him to return to full physical duties. PMID:22319988

  17. Recovering the Star Formation Rate in the Solar Neighborhood

    NASA Astrophysics Data System (ADS)

    Cignoni, M.; Degl'Innocenti, S.; Moroni, P. G. P.; Shore, S. N.

    2007-11-01

    This paper develops a method for obtaining the star formation histories of a mixed, resolved population through the use of color-magnitude diagrams (CMDs). The method is applied to the derivation of the local star formation rate, analyzing the observations of the Hipparcos satellite through a comparison with synthetic CMDs computed for different star formation histories with an updated stellar evolution library. Parallax and photometric uncertainties are included explicitly and corrected using the Bayesian Richardson-Lucy algorithm. We find that the solar neighborhood star formation rate has a characteristic timescale for variation of about 6 Gyr, with a maximum activity close to 3 Gyr ago.

  18. Vorticity generation by contoured wall injectors

    NASA Technical Reports Server (NTRS)

    Waitz, Ian A.; Marble, Frank E.; Zukoski, Edward E.

    1992-01-01

    A class of contoured wall fuel injectors was designed to enable shock-enhancement of hypervelocity mixing for supersonic combustion ramjet applications. Previous studies of these geometries left unresolved questions concerning the relative importance of various axial vorticity sources in mixing the injectant with the freestream. The present study is a numerical simulation of two generic fuel injectors which is aimed at elucidating the relative roles of axial vorticity sources including: baroclinic torque through shock-impingement, cross-stream shear, turning of boundary layer vorticity, shock curvature, and diffusive flux. Both the magnitude of the circulation, and the location of vorticity with respect to the mixing interface were considered. Baroclinic torque and cross-stream shear were found to be most important in convectively mixing the injectant with the freestream, with the former providing for deposition of vorticity directly on the fuel/air interface.

  19. The aperture problem in contoured stimuli

    PubMed Central

    Kane, David; Bex, Peter J.; Dakin, Steven C.

    2010-01-01

    A moving object elicits responses from V1 neurons tuned to a broad range of locations, directions, and spatiotemporal frequencies. Global pooling of such signals can overcome their intrinsic ambiguity in relation to the object’s direction/speed (the “aperture problem”); here we examine the role of low-spatial frequencies (SF) and second-order statistics in this process. Subjects made a 2AFC fine direction-discrimination judgement of ‘naturally’ contoured stimuli viewed rigidly translating behind a series of small circular apertures. This configuration allowed us to manipulate the scene in several ways; by randomly switching which portion of the stimulus was presented behind each aperture or by occluding certain spatial frequency bands. We report that global motion integration is (a) largely insensitive to the second-order statistics of such stimuli and (b) is rigidly broadband even in the presence of a disrupted low SF component. PMID:19810794

  20. Impact of contour on aesthetic judgments and approach-avoidance decisions in architecture.

    PubMed

    Vartanian, Oshin; Navarrete, Gorka; Chatterjee, Anjan; Fich, Lars Brorson; Leder, Helmut; Modroño, Cristián; Nadal, Marcos; Rostrup, Nicolai; Skov, Martin

    2013-06-18

    On average, we urban dwellers spend about 90% of our time indoors, and share the intuition that the physical features of the places we live and work in influence how we feel and act. However, there is surprisingly little research on how architecture impacts behavior, much less on how it influences brain function. To begin closing this gap, we conducted a functional magnetic resonance imaging study to examine how systematic variation in contour impacts aesthetic judgments and approach-avoidance decisions, outcome measures of interest to both architects and users of spaces alike. As predicted, participants were more likely to judge spaces as beautiful if they were curvilinear than rectilinear. Neuroanatomically, when contemplating beauty, curvilinear contour activated the anterior cingulate cortex exclusively, a region strongly responsive to the reward properties and emotional salience of objects. Complementing this finding, pleasantness--the valence dimension of the affect circumplex--accounted for nearly 60% of the variance in beauty ratings. Furthermore, activation in a distributed brain network known to underlie the aesthetic evaluation of different types of visual stimuli covaried with beauty ratings. In contrast, contour did not affect approach-avoidance decisions, although curvilinear spaces activated the visual cortex. The results suggest that the well-established effect of contour on aesthetic preference can be extended to architecture. Furthermore, the combination of our behavioral and neural evidence underscores the role of emotion in our preference for curvilinear objects in this domain. PMID:23754408