[Overload in the informal caregivers of patients with multiple comorbidities in an urban area].

PubMed

Álvarez-Tello, Margarita; Casado-Mejía, Rosa; Ortega-Calvo, Manuel; Ruiz-Arias, Esperanza

2012-01-01

The aim of the study was, to determine the profile of the family caregiver of patients with multiple pathologies, identify factors associated with overload, and construct predictive models using items from the Caregiver Strain Index (CSI). A cross-sectional study of caregivers of patients with multiple comorbidities who attended an urban health centre. Data were collected from health records and questionnaires (Barthel index, Pfeiffer index, and CSI). Statistical analysis was performed using measures of central tendency and dispersion, and by building multivariate models with binary logistic regression with the CSI items as predictors (program R version 2.14.0). The sample included 67 caregivers, with a mean age of 64.69 years (standard deviation=12.71, median 62 years), of whom 74.6% were women, 35.8% were wives, and 32.8% were daughters. The level of dependence of the patients cared for was total/severe in 77.6%, and moderate in 12% (Barthel), and 47.8% had some level of cognitive impairment (Pfeiffer). A CSI equal or greater than 7 was seen in 47.8% of caregivers, identifying life problems in more than 40% of them such as, restriction of social life, physical exertion, discomfort with change, bad behaviour, personal and family emotional changes, and sleep disturbances. Item 4 of the CSI, analysing the social restriction, was the one that showed a greater significance in the predictive multivariate model. Item 12 (economic burden) was the most significant with age in patients with cognitive impairment. Women tend to take the role of caregiver at an earlier age than men in the urban environment studied, and items from CSI showed that items 4 (social restrictions) and 12 (economic burden) have more significance in the predictive models constructed with Binary Logistic Regression. Copyright © 2012 Elsevier España, S.L. All rights reserved.

No rationale for 1 variable per 10 events criterion for binary logistic regression analysis.

PubMed

van Smeden, Maarten; de Groot, Joris A H; Moons, Karel G M; Collins, Gary S; Altman, Douglas G; Eijkemans, Marinus J C; Reitsma, Johannes B

2016-11-24

Ten events per variable (EPV) is a widely advocated minimal criterion for sample size considerations in logistic regression analysis. Of three previous simulation studies that examined this minimal EPV criterion only one supports the use of a minimum of 10 EPV. In this paper, we examine the reasons for substantial differences between these extensive simulation studies. The current study uses Monte Carlo simulations to evaluate small sample bias, coverage of confidence intervals and mean square error of logit coefficients. Logistic regression models fitted by maximum likelihood and a modified estimation procedure, known as Firth's correction, are compared. The results show that besides EPV, the problems associated with low EPV depend on other factors such as the total sample size. It is also demonstrated that simulation results can be dominated by even a few simulated data sets for which the prediction of the outcome by the covariates is perfect ('separation'). We reveal that different approaches for identifying and handling separation leads to substantially different simulation results. We further show that Firth's correction can be used to improve the accuracy of regression coefficients and alleviate the problems associated with separation. The current evidence supporting EPV rules for binary logistic regression is weak. Given our findings, there is an urgent need for new research to provide guidance for supporting sample size considerations for binary logistic regression analysis.

Diagnostic accuracy of serum antibodies to human papillomavirus type 16 early antigens in the detection of human papillomavirus-related oropharyngeal cancer.

PubMed

Dahlstrom, Kristina R; Anderson, Karen S; Field, Matthew S; Chowell, Diego; Ning, Jing; Li, Nan; Wei, Qingyi; Li, Guojun; Sturgis, Erich M

2017-12-15

Because of the current epidemic of human papillomavirus (HPV)-related oropharyngeal cancer (OPC), a screening strategy is urgently needed. The presence of serum antibodies to HPV-16 early (E) antigens is associated with an increased risk for OPC. The purpose of this study was to evaluate the diagnostic accuracy of antibodies to a panel of HPV-16 E antigens in screening for OPC. This case-control study included 378 patients with OPC, 153 patients with nonoropharyngeal head and neck cancer (non-OPC), and 782 healthy control subjects. The tumor HPV status was determined with p16 immunohistochemistry and HPV in situ hybridization. HPV-16 E antibody levels in serum were identified with an enzyme-linked immunosorbent assay. A trained binary logistic regression model based on the combination of all E antigens was predefined and applied to the data set. The sensitivity and specificity of the assay for distinguishing HPV-related OPC from controls were calculated. Logistic regression analysis was used to calculate odds ratios with 95% confidence intervals for the association of head and neck cancer with the antibody status. Of the 378 patients with OPC, 348 had p16-positive OPC. HPV-16 E antibody levels were significantly higher among patients with p16-positive OPC but not among patients with non-OPC or among controls. Serology showed high sensitivity and specificity for HPV-related OPC (binary classifier: 83% sensitivity and 99% specificity for p16-positive OPC). A trained binary classification algorithm that incorporates information about multiple E antibodies has high sensitivity and specificity and may be advantageous for risk stratification in future screening trials. Cancer 2017;123:4886-94. © 2017 American Cancer Society. © 2017 American Cancer Society.

Modeling the dynamics of urban growth using multinomial logistic regression: a case study of Jiayu County, Hubei Province, China

NASA Astrophysics Data System (ADS)

Nong, Yu; Du, Qingyun; Wang, Kun; Miao, Lei; Zhang, Weiwei

2008-10-01

Urban growth modeling, one of the most important aspects of land use and land cover change study, has attracted substantial attention because it helps to comprehend the mechanisms of land use change thus helps relevant policies made. This study applied multinomial logistic regression to model urban growth in the Jiayu county of Hubei province, China to discover the relationship between urban growth and the driving forces of which biophysical and social-economic factors are selected as independent variables. This type of regression is similar to binary logistic regression, but it is more general because the dependent variable is not restricted to two categories, as those previous studies did. The multinomial one can simulate the process of multiple land use competition between urban land, bare land, cultivated land and orchard land. Taking the land use type of Urban as reference category, parameters could be estimated with odds ratio. A probability map is generated from the model to predict where urban growth will occur as a result of the computation.

A simple measure of cognitive reserve is relevant for cognitive performance in MS patients.

PubMed

Della Corte, Marida; Santangelo, Gabriella; Bisecco, Alvino; Sacco, Rosaria; Siciliano, Mattia; d'Ambrosio, Alessandro; Docimo, Renato; Cuomo, Teresa; Lavorgna, Luigi; Bonavita, Simona; Tedeschi, Gioacchino; Gallo, Antonio

2018-05-04

Cognitive reserve (CR) contributes to preserve cognition despite brain damage. This theory has been applied to multiple sclerosis (MS) to explain the partial relationship between cognition and MRI markers of brain pathology. Our aim was to determine the relationship between two measures of CR and cognition in MS. One hundred and forty-seven MS patients were enrolled. Cognition was assessed using the Rao's Brief Repeatable Battery and the Stroop Test. CR was measured as the vocabulary subtest of the WAIS-R score (VOC) and the number of years of formal education (EDU). Regression analysis included raw score data on each neuropsychological (NP) test as dependent variables and demographic/clinical parameters, VOC, and EDU as independent predictors. A binary logistic regression analysis including clinical/CR parameters as covariates and absence/presence of cognitive deficits as dependent variables was performed too. VOC, but not EDU, was strongly correlated with performances at all ten NP tests. EDU was correlated with executive performances. The binary logistic regression showed that only the Expanded Disability Status Scale (EDSS) and VOC were independently correlated with the presence/absence of CD. The lower the VOC and/or the higher the EDSS, the higher the frequency of CD. In conclusion, our study supports the relevance of CR in subtending cognitive performances and the presence of CD in MS patients.

Missing Data in Alcohol Clinical Trials with Binary Outcomes

PubMed Central

Hallgren, Kevin A.; Witkiewitz, Katie; Kranzler, Henry R.; Falk, Daniel E.; Litten, Raye Z.; O’Malley, Stephanie S.; Anton, Raymond F.

2017-01-01

Background Missing data are common in alcohol clinical trials for both continuous and binary endpoints. Approaches to handle missing data have been explored for continuous outcomes, yet no studies have compared missing data approaches for binary outcomes (e.g., abstinence, no heavy drinking days). The present study compares approaches to modeling binary outcomes with missing data in the COMBINE study. Method We included participants in the COMBINE Study who had complete drinking data during treatment and who were assigned to active medication or placebo conditions (N=1146). Using simulation methods, missing data were introduced under common scenarios with varying sample sizes and amounts of missing data. Logistic regression was used to estimate the effect of naltrexone (vs. placebo) in predicting any drinking and any heavy drinking outcomes at the end of treatment using four analytic approaches: complete case analysis (CCA), last observation carried forward (LOCF), the worst-case scenario of missing equals any drinking or heavy drinking (WCS), and multiple imputation (MI). In separate analyses, these approaches were compared when drinking data were manually deleted for those participants who discontinued treatment but continued to provide drinking data. Results WCS produced the greatest amount of bias in treatment effect estimates. MI usually yielded less biased estimates than WCS and CCA in the simulated data, and performed considerably better than LOCF when estimating treatment effects among individuals who discontinued treatment. Conclusions Missing data can introduce bias in treatment effect estimates in alcohol clinical trials. Researchers should utilize modern missing data methods, including MI, and avoid WCS and CCA when analyzing binary alcohol clinical trial outcomes. PMID:27254113

Missing Data in Alcohol Clinical Trials with Binary Outcomes.

PubMed

Hallgren, Kevin A; Witkiewitz, Katie; Kranzler, Henry R; Falk, Daniel E; Litten, Raye Z; O'Malley, Stephanie S; Anton, Raymond F

2016-07-01

Missing data are common in alcohol clinical trials for both continuous and binary end points. Approaches to handle missing data have been explored for continuous outcomes, yet no studies have compared missing data approaches for binary outcomes (e.g., abstinence, no heavy drinking days). This study compares approaches to modeling binary outcomes with missing data in the COMBINE study. We included participants in the COMBINE study who had complete drinking data during treatment and who were assigned to active medication or placebo conditions (N = 1,146). Using simulation methods, missing data were introduced under common scenarios with varying sample sizes and amounts of missing data. Logistic regression was used to estimate the effect of naltrexone (vs. placebo) in predicting any drinking and any heavy drinking outcomes at the end of treatment using 4 analytic approaches: complete case analysis (CCA), last observation carried forward (LOCF), the worst case scenario (WCS) of missing equals any drinking or heavy drinking, and multiple imputation (MI). In separate analyses, these approaches were compared when drinking data were manually deleted for those participants who discontinued treatment but continued to provide drinking data. WCS produced the greatest amount of bias in treatment effect estimates. MI usually yielded less biased estimates than WCS and CCA in the simulated data and performed considerably better than LOCF when estimating treatment effects among individuals who discontinued treatment. Missing data can introduce bias in treatment effect estimates in alcohol clinical trials. Researchers should utilize modern missing data methods, including MI, and avoid WCS and CCA when analyzing binary alcohol clinical trial outcomes. Copyright © 2016 by the Research Society on Alcoholism.

The extraneous eclipses on binary light curves: KIC 5255552, KIC 10091110, and KIC 11495766

NASA Astrophysics Data System (ADS)

Zhang, J.; Qian, S. B.; Wang, S. M.; Sun, L. L.; Wu, Y.; Jiang, L. Q.

2018-03-01

Aims: We aim to find more eclipsing multiple systems and obtain their parameters, thus increasing our understanding of multiple systems. Methods: The extraneous eclipses on the Kepler binary light curves indicating extraneous bodies were searched. The binary light curves were analyzed using the binary model, and the extraneous eclipses were studied on their periodicity and shape changes. Results: Three binaries with extraneous eclipses on the binary light curves were found and studied based on the Kepler observations. The object KIC 5255552 is an eclipsing triple system with a fast changing inner binary and an outer companion uncovered by three groups of extraneous eclipses of 862.1(±0.1) d period. The KIC 10091110 is suggested to be a double eclipsing binary system with several possible extraordinary coincidences: the two binaries share similar extremely small mass ratios (0.060(13) and 0.0564(18)), similar mean primary densities (0.3264(42) ρ⊙ and 0.3019(28) ρ⊙), and, most notably, the ratio of the two binaries' periods is very close to integer 2 (8.5303353/4.2185174 = 2.022). The KIC 11495766 is a probable triple system with a 120.73 d period binary and (at least) one non-eclipse companion. Furthermore, very close to it in the celestial sphere, there is a blended background stellar binary of 8.3404432 d period. A first list of 25 eclipsing multiple candidates is presented, with the hope that it will be beneficial for study of eclipsing multiples.

Using Logistic Regression To Predict the Probability of Debris Flows Occurring in Areas Recently Burned By Wildland Fires

USGS Publications Warehouse

Rupert, Michael G.; Cannon, Susan H.; Gartner, Joseph E.

2003-01-01

Logistic regression was used to predict the probability of debris flows occurring in areas recently burned by wildland fires. Multiple logistic regression is conceptually similar to multiple linear regression because statistical relations between one dependent variable and several independent variables are evaluated. In logistic regression, however, the dependent variable is transformed to a binary variable (debris flow did or did not occur), and the actual probability of the debris flow occurring is statistically modeled. Data from 399 basins located within 15 wildland fires that burned during 2000-2002 in Colorado, Idaho, Montana, and New Mexico were evaluated. More than 35 independent variables describing the burn severity, geology, land surface gradient, rainfall, and soil properties were evaluated. The models were developed as follows: (1) Basins that did and did not produce debris flows were delineated from National Elevation Data using a Geographic Information System (GIS). (2) Data describing the burn severity, geology, land surface gradient, rainfall, and soil properties were determined for each basin. These data were then downloaded to a statistics software package for analysis using logistic regression. (3) Relations between the occurrence/non-occurrence of debris flows and burn severity, geology, land surface gradient, rainfall, and soil properties were evaluated and several preliminary multivariate logistic regression models were constructed. All possible combinations of independent variables were evaluated to determine which combination produced the most effective model. The multivariate model that best predicted the occurrence of debris flows was selected. (4) The multivariate logistic regression model was entered into a GIS, and a map showing the probability of debris flows was constructed. The most effective model incorporates the percentage of each basin with slope greater than 30 percent, percentage of land burned at medium and high burn severity in each basin, particle size sorting, average storm intensity (millimeters per hour), soil organic matter content, soil permeability, and soil drainage. The results of this study demonstrate that logistic regression is a valuable tool for predicting the probability of debris flows occurring in recently-burned landscapes.

Multiplicity in Early Stellar Evolution

NASA Astrophysics Data System (ADS)

Reipurth, B.; Clarke, C. J.; Boss, A. P.; Goodwin, S. P.; Rodríguez, L. F.; Stassun, K. G.; Tokovinin, A.; Zinnecker, H.

Observations from optical to centimeter wavelengths have demonstrated that multiple systems of two or more bodies is the norm at all stellar evolutionary stages. Multiple systems are widely agreed to result from the collapse and fragmentation of cloud cores, despite the inhibiting influence of magnetic fields. Surveys of class 0 protostars with millimeter interferometers have revealed a very high multiplicity frequency of about 2/3, even though there are observational difficulties in resolving close protobinaries, thus supporting the possibility that all stars could be born in multiple systems. Near-infrared adaptive optics observations of class I protostars show a lower binary frequency relative to the class 0 phase, a declining trend that continues through the class II/III stages to the field population. This loss of companions is a natural consequence of dynamical interplay in small multiple systems, leading to ejection of members. We discuss observational consequences of this dynamical evolution, and its influence on circumstellar disks, and we review the evolution of circumbinary disks and their role in defining binary mass ratios. Special attention is paid to eclipsing PMS binaries, which allow for observational tests of evolutionary models of early stellar evolution. Many stars are born in clusters and small groups, and we discuss how interactions in dense stellar environments can significantly alter the distribution of binary separations through dissolution of wider binaries. The binaries and multiples we find in the field are the survivors of these internal and external destructive processes, and we provide a detailed overview of the multiplicity statistics of the field, which form a boundary condition for all models of binary evolution. Finally, we discuss various formation mechanisms for massive binaries, and the properties of massive trapezia.

PARAMETRIC AND NON PARAMETRIC (MARS: MULTIVARIATE ADDITIVE REGRESSION SPLINES) LOGISTIC REGRESSIONS FOR PREDICTION OF A DICHOTOMOUS RESPONSE VARIABLE WITH AN EXAMPLE FOR PRESENCE/ABSENCE OF AMPHIBIANS

EPA Science Inventory

The purpose of this report is to provide a reference manual that could be used by investigators for making informed use of logistic regression using two methods (standard logistic regression and MARS). The details for analyses of relationships between a dependent binary response ...

Analyzing Student Learning Outcomes: Usefulness of Logistic and Cox Regression Models. IR Applications, Volume 5

ERIC Educational Resources Information Center

Chen, Chau-Kuang

2005-01-01

Logistic and Cox regression methods are practical tools used to model the relationships between certain student learning outcomes and their relevant explanatory variables. The logistic regression model fits an S-shaped curve into a binary outcome with data points of zero and one. The Cox regression model allows investigators to study the duration…

A nonparametric multiple imputation approach for missing categorical data.

PubMed

Zhou, Muhan; He, Yulei; Yu, Mandi; Hsu, Chiu-Hsieh

2017-06-06

Incomplete categorical variables with more than two categories are common in public health data. However, most of the existing missing-data methods do not use the information from nonresponse (missingness) probabilities. We propose a nearest-neighbour multiple imputation approach to impute a missing at random categorical outcome and to estimate the proportion of each category. The donor set for imputation is formed by measuring distances between each missing value with other non-missing values. The distance function is calculated based on a predictive score, which is derived from two working models: one fits a multinomial logistic regression for predicting the missing categorical outcome (the outcome model) and the other fits a logistic regression for predicting missingness probabilities (the missingness model). A weighting scheme is used to accommodate contributions from two working models when generating the predictive score. A missing value is imputed by randomly selecting one of the non-missing values with the smallest distances. We conduct a simulation to evaluate the performance of the proposed method and compare it with several alternative methods. A real-data application is also presented. The simulation study suggests that the proposed method performs well when missingness probabilities are not extreme under some misspecifications of the working models. However, the calibration estimator, which is also based on two working models, can be highly unstable when missingness probabilities for some observations are extremely high. In this scenario, the proposed method produces more stable and better estimates. In addition, proper weights need to be chosen to balance the contributions from the two working models and achieve optimal results for the proposed method. We conclude that the proposed multiple imputation method is a reasonable approach to dealing with missing categorical outcome data with more than two levels for assessing the distribution of the outcome. In terms of the choices for the working models, we suggest a multinomial logistic regression for predicting the missing outcome and a binary logistic regression for predicting the missingness probability.

Dynamical evolution of young binaries and multiple systems

NASA Astrophysics Data System (ADS)

Reipurth, B.

Most stars, and perhaps all, are born in small multiple systems whose components interact, leading to chaotic dynamic behavior. Some components are ejected, either into distant orbits or into outright escapes, while the remaining components form temporary and eventually permanent binary systems. More than half of all such breakups of multiple systems occur during the protostellar phase, leading to the occasional ejection of protostars outside their nascent cloud cores. Such orphaned protostars are observed as wide companions to embedded protostars, and thus allow the direct study of protostellar objects. Dynamic interactions during early stellar evolution explain the shape and enormous width of the separation distribution function of binaries, from close spectroscopic binaries to the widest binaries.

Examining the Link Between Public Transit Use and Active Commuting

PubMed Central

Bopp, Melissa; Gayah, Vikash V.; Campbell, Matthew E.

2015-01-01

Background: An established relationship exists between public transportation (PT) use and physical activity. However, there is limited literature that examines the link between PT use and active commuting (AC) behavior. This study examines this link to determine if PT users commute more by active modes. Methods: A volunteer, convenience sample of adults (n = 748) completed an online survey about AC/PT patterns, demographic, psychosocial, community and environmental factors. t-test compared differences between PT riders and non-PT riders. Binary logistic regression analyses examined the effect of multiple factors on AC and a full logistic regression model was conducted to examine AC. Results: Non-PT riders (n = 596) reported less AC than PT riders. There were several significant relationships with AC for demographic, interpersonal, worksite, community and environmental factors when considering PT use. The logistic multivariate analysis for included age, number of children and perceived distance to work as negative predictors and PT use, feelings of bad weather and lack of on-street bike lanes as a barrier to AC, perceived behavioral control and spouse AC were positive predictors. Conclusions: This study revealed the complex relationship between AC and PT use. Further research should investigate how AC and public transit use are related. PMID:25898405

Examining the link between public transit use and active commuting.

PubMed

Bopp, Melissa; Gayah, Vikash V; Campbell, Matthew E

2015-04-17

An established relationship exists between public transportation (PT) use and physical activity. However, there is limited literature that examines the link between PT use and active commuting (AC) behavior. This study examines this link to determine if PT users commute more by active modes. A volunteer, convenience sample of adults (n = 748) completed an online survey about AC/PT patterns, demographic, psychosocial, community and environmental factors. t-test compared differences between PT riders and non-PT riders. Binary logistic regression analyses examined the effect of multiple factors on AC and a full logistic regression model was conducted to examine AC. Non-PT riders (n = 596) reported less AC than PT riders. There were several significant relationships with AC for demographic, interpersonal, worksite, community and environmental factors when considering PT use. The logistic multivariate analysis for included age, number of children and perceived distance to work as negative predictors and PT use, feelings of bad weather and lack of on-street bike lanes as a barrier to AC, perceived behavioral control and spouse AC were positive predictors. This study revealed the complex relationship between AC and PT use. Further research should investigate how AC and public transit use are related.

The crux of the method: assumptions in ordinary least squares and logistic regression.

PubMed

Long, Rebecca G

2008-10-01

Logistic regression has increasingly become the tool of choice when analyzing data with a binary dependent variable. While resources relating to the technique are widely available, clear discussions of why logistic regression should be used in place of ordinary least squares regression are difficult to find. The current paper compares and contrasts the assumptions of ordinary least squares with those of logistic regression and explains why logistic regression's looser assumptions make it adept at handling violations of the more important assumptions in ordinary least squares.

Relationships Among Substance Use, Multiple Sexual Partners, and Condomless Sex.

PubMed

Zhao, Yunchuan Lucy; Kim, Heejung; Peltzer, Jill

2017-04-01

Male and female students manifest different behaviors in condomless sex. This cross-sectional, exploratory, correlational study examined the differences in risk factors for condomless sex between male and female high school students, using secondary data from 4,968 sexually active males and females participating in the 2011 National Youth Risk Behavior Survey. Results in descriptive statistics and multivariate binary logistic regressions revealed that condomless sex was reported as 39.70% in general. A greater proportion of females engaged in condomless sex (23.26%) than did males (16.44%). Physical abuse by sex partners was a common reason for failure to use condoms regardless of gender. Lower condom use was found in (1) those experiencing forced sex by a partner in males, (2) female smokers, and (3) female with multiple sex partners. Thus, sexual health education should address the different risk factors and consider gender characteristics to reduce condomless sex.

Hierarchical faunal filters: An approach to assessing effects of habitat and nonnative species on native fishes

USGS Publications Warehouse

Quist, M.C.; Rahel, F.J.; Hubert, W.A.

2005-01-01

Understanding factors related to the occurrence of species across multiple spatial and temporal scales is critical to the conservation and management of native fishes, especially for those species at the edge of their natural distribution. We used the concept of hierarchical faunal filters to provide a framework for investigating the influence of habitat characteristics and normative piscivores on the occurrence of 10 native fishes in streams of the North Platte River watershed in Wyoming. Three faunal filters were developed for each species: (i) large-scale biogeographic, (ii) local abiotic, and (iii) biotic. The large-scale biogeographic filter, composed of elevation and stream-size thresholds, was used to determine the boundaries within which each species might be expected to occur. Then, a local abiotic filter (i.e., habitat associations), developed using binary logistic-regression analysis, estimated the probability of occurrence of each species from features such as maximum depth, substrate composition, submergent aquatic vegetation, woody debris, and channel morphology (e.g., amount of pool habitat). Lastly, a biotic faunal filter was developed using binary logistic regression to estimate the probability of occurrence of each species relative to the abundance of nonnative piscivores in a reach. Conceptualising fish assemblages within a framework of hierarchical faunal filters is simple and logical, helps direct conservation and management activities, and provides important information on the ecology of fishes in the western Great Plains of North America. ?? Blackwell Munksgaard, 2004.

Racial residential segregation and preterm birth: built environment as a mediator.

PubMed

Anthopolos, Rebecca; Kaufman, Jay S; Messer, Lynne C; Miranda, Marie Lynn

2014-05-01

Racial residential segregation has been associated with preterm birth. Few studies have examined mediating pathways, in part because, with binary outcomes, indirect effects estimated from multiplicative models generally lack causal interpretation. We develop a method to estimate additive-scale natural direct and indirect effects from logistic regression. We then evaluate whether segregation operates through poor-quality built environment to affect preterm birth. To estimate natural direct and indirect effects, we derive risk differences from logistic regression coefficients. Birth records (2000-2008) for Durham, North Carolina, were linked to neighborhood-level measures of racial isolation and a composite construct of poor-quality built environment. We decomposed the total effect of racial isolation on preterm birth into direct and indirect effects. The adjusted total effect of an interquartile increase in racial isolation on preterm birth was an extra 27 preterm events per 1000 births (risk difference = 0.027 [95% confidence interval = 0.007 to 0.047]). With poor-quality built environment held at the level it would take under isolation at the 25th percentile, the direct effect of an interquartile increase in isolation was 0.022 (-0.001 to 0.042). Poor-quality built environment accounted for 35% (11% to 65%) of the total effect. Our methodology facilitates the estimation of additive-scale natural effects with binary outcomes. In this study, the total effect of racial segregation on preterm birth was partially mediated by poor-quality built environment.

Modelling long-term fire occurrence factors in Spain by accounting for local variations with geographically weighted regression

NASA Astrophysics Data System (ADS)

Martínez-Fernández, J.; Chuvieco, E.; Koutsias, N.

2013-02-01

Humans are responsible for most forest fires in Europe, but anthropogenic factors behind these events are still poorly understood. We tried to identify the driving factors of human-caused fire occurrence in Spain by applying two different statistical approaches. Firstly, assuming stationary processes for the whole country, we created models based on multiple linear regression and binary logistic regression to find factors associated with fire density and fire presence, respectively. Secondly, we used geographically weighted regression (GWR) to better understand and explore the local and regional variations of those factors behind human-caused fire occurrence. The number of human-caused fires occurring within a 25-yr period (1983-2007) was computed for each of the 7638 Spanish mainland municipalities, creating a binary variable (fire/no fire) to develop logistic models, and a continuous variable (fire density) to build standard linear regression models. A total of 383 657 fires were registered in the study dataset. The binary logistic model, which estimates the probability of having/not having a fire, successfully classified 76.4% of the total observations, while the ordinary least squares (OLS) regression model explained 53% of the variation of the fire density patterns (adjusted R2 = 0.53). Both approaches confirmed, in addition to forest and climatic variables, the importance of variables related with agrarian activities, land abandonment, rural population exodus and developmental processes as underlying factors of fire occurrence. For the GWR approach, the explanatory power of the GW linear model for fire density using an adaptive bandwidth increased from 53% to 67%, while for the GW logistic model the correctly classified observations improved only slightly, from 76.4% to 78.4%, but significantly according to the corrected Akaike Information Criterion (AICc), from 3451.19 to 3321.19. The results from GWR indicated a significant spatial variation in the local parameter estimates for all the variables and an important reduction of the autocorrelation in the residuals of the GW linear model. Despite the fitting improvement of local models, GW regression, more than an alternative to "global" or traditional regression modelling, seems to be a valuable complement to explore the non-stationary relationships between the response variable and the explanatory variables. The synergy of global and local modelling provides insights into fire management and policy and helps further our understanding of the fire problem over large areas while at the same time recognizing its local character.

Multiple imputation for handling missing outcome data when estimating the relative risk.

PubMed

Sullivan, Thomas R; Lee, Katherine J; Ryan, Philip; Salter, Amy B

2017-09-06

Multiple imputation is a popular approach to handling missing data in medical research, yet little is known about its applicability for estimating the relative risk. Standard methods for imputing incomplete binary outcomes involve logistic regression or an assumption of multivariate normality, whereas relative risks are typically estimated using log binomial models. It is unclear whether misspecification of the imputation model in this setting could lead to biased parameter estimates. Using simulated data, we evaluated the performance of multiple imputation for handling missing data prior to estimating adjusted relative risks from a correctly specified multivariable log binomial model. We considered an arbitrary pattern of missing data in both outcome and exposure variables, with missing data induced under missing at random mechanisms. Focusing on standard model-based methods of multiple imputation, missing data were imputed using multivariate normal imputation or fully conditional specification with a logistic imputation model for the outcome. Multivariate normal imputation performed poorly in the simulation study, consistently producing estimates of the relative risk that were biased towards the null. Despite outperforming multivariate normal imputation, fully conditional specification also produced somewhat biased estimates, with greater bias observed for higher outcome prevalences and larger relative risks. Deleting imputed outcomes from analysis datasets did not improve the performance of fully conditional specification. Both multivariate normal imputation and fully conditional specification produced biased estimates of the relative risk, presumably since both use a misspecified imputation model. Based on simulation results, we recommend researchers use fully conditional specification rather than multivariate normal imputation and retain imputed outcomes in the analysis when estimating relative risks. However fully conditional specification is not without its shortcomings, and so further research is needed to identify optimal approaches for relative risk estimation within the multiple imputation framework.

Identification of binary and multiple systems in TGAS using the Virtual Observatory

NASA Astrophysics Data System (ADS)

Jiménez-Esteban, F.; Solano, E.

2018-04-01

Binary and multiple stars have long provided an effective method of testing stellar formation and evolution theories. In particular, wide binary systems with separations > 20,000 au are particularly challenging as their physical separations are beyond the typical size of a collapsing cloud core (5,000 - 10,000 au). We present here a preliminary work in which we make use of the TGAS catalogue and Virtual Observatory tools and services (Aladin, TOPCAT, STILTS, VOSA, VizieR) to identify binary and multiple star candidate systems. The catalogue will be available from the Spanish VO portal (http://svo.cab.inta-csic.es) in the coming months.

Beyond logistic regression: structural equations modelling for binary variables and its application to investigating unobserved confounders.

PubMed

Kupek, Emil

2006-03-15

Structural equation modelling (SEM) has been increasingly used in medical statistics for solving a system of related regression equations. However, a great obstacle for its wider use has been its difficulty in handling categorical variables within the framework of generalised linear models. A large data set with a known structure among two related outcomes and three independent variables was generated to investigate the use of Yule's transformation of odds ratio (OR) into Q-metric by (OR-1)/(OR+1) to approximate Pearson's correlation coefficients between binary variables whose covariance structure can be further analysed by SEM. Percent of correctly classified events and non-events was compared with the classification obtained by logistic regression. The performance of SEM based on Q-metric was also checked on a small (N = 100) random sample of the data generated and on a real data set. SEM successfully recovered the generated model structure. SEM of real data suggested a significant influence of a latent confounding variable which would have not been detectable by standard logistic regression. SEM classification performance was broadly similar to that of the logistic regression. The analysis of binary data can be greatly enhanced by Yule's transformation of odds ratios into estimated correlation matrix that can be further analysed by SEM. The interpretation of results is aided by expressing them as odds ratios which are the most frequently used measure of effect in medical statistics.

Unitary Response Regression Models

ERIC Educational Resources Information Center

Lipovetsky, S.

2007-01-01

The dependent variable in a regular linear regression is a numerical variable, and in a logistic regression it is a binary or categorical variable. In these models the dependent variable has varying values. However, there are problems yielding an identity output of a constant value which can also be modelled in a linear or logistic regression with…

The Effect of Latent Binary Variables on the Uncertainty of the Prediction of a Dichotomous Outcome Using Logistic Regression Based Propensity Score Matching.

PubMed

Szekér, Szabolcs; Vathy-Fogarassy, Ágnes

2018-01-01

Logistic regression based propensity score matching is a widely used method in case-control studies to select the individuals of the control group. This method creates a suitable control group if all factors affecting the output variable are known. However, if relevant latent variables exist as well, which are not taken into account during the calculations, the quality of the control group is uncertain. In this paper, we present a statistics-based research in which we try to determine the relationship between the accuracy of the logistic regression model and the uncertainty of the dependent variable of the control group defined by propensity score matching. Our analyses show that there is a linear correlation between the fit of the logistic regression model and the uncertainty of the output variable. In certain cases, a latent binary explanatory variable can result in a relative error of up to 70% in the prediction of the outcome variable. The observed phenomenon calls the attention of analysts to an important point, which must be taken into account when deducting conclusions.

Potentially Modifiable Factors Associated With Physical Activity in Individuals With Multiple Sclerosis.

PubMed

Reider, Nadia; Salter, Amber R; Cutter, Gary R; Tyry, Tuula; Marrie, Ruth Ann

2017-04-01

Physical activity levels among persons with multiple sclerosis (MS) are worryingly low. We aimed to identify the factors associated with physical activity for people with MS, with an emphasis on factors that have not been studied previously (bladder and hand dysfunction) and are potentially modifiable. This study was a secondary analysis of data collected in the spring of 2012 during the North American Research Committee on Multiple Sclerosis (NARCOMS) Registry. NARCOMS participants were surveyed regarding smoking using questions from the Behavioral Risk Factor Surveillance Survey; disability using the Patient Determined Disease Steps; fatigue, cognition, spasticity, sensory, bladder, vision and hand function using self-reported Performance Scales; health literacy using the Medical Term Recognition Test; and physical activity using questions from the Health Information National Trends Survey. We used a forward binary logistic regression to develop a predictive model in which physical activity was the outcome variable. Of 8,755 respondents, 1,707 (19.5%) were classified as active and 7,068 (80.5%) as inactive. In logistic regression, being a current smoker, moderate or severe level of disability, depression, fatigue, hand, or bladder dysfunction and minimal to mild spasticity were associated with lower odds of meeting physical activity guidelines. MS type was not linked to activity level. Several modifiable clinical and lifestyle factors influenced physical activity in MS. Prospective studies are needed to evaluate whether modification of these factors can increase physical activity participation in persons with MS. © 2016 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Binary Logistic Regression Versus Boosted Regression Trees in Assessing Landslide Susceptibility for Multiple-Occurring Regional Landslide Events: Application to the 2009 Storm Event in Messina (Sicily, southern Italy).

NASA Astrophysics Data System (ADS)

Lombardo, L.; Cama, M.; Maerker, M.; Parisi, L.; Rotigliano, E.

2014-12-01

This study aims at comparing the performances of Binary Logistic Regression (BLR) and Boosted Regression Trees (BRT) methods in assessing landslide susceptibility for multiple-occurrence regional landslide events within the Mediterranean region. A test area was selected in the north-eastern sector of Sicily (southern Italy), corresponding to the catchments of the Briga and the Giampilieri streams both stretching for few kilometres from the Peloritan ridge (eastern Sicily, Italy) to the Ionian sea. This area was struck on the 1st October 2009 by an extreme climatic event resulting in thousands of rapid shallow landslides, mainly of debris flows and debris avalanches types involving the weathered layer of a low to high grade metamorphic bedrock. Exploiting the same set of predictors and the 2009 landslide archive, BLR- and BRT-based susceptibility models were obtained for the two catchments separately, adopting a random partition (RP) technique for validation; besides, the models trained in one of the two catchments (Briga) were tested in predicting the landslide distribution in the other (Giampilieri), adopting a spatial partition (SP) based validation procedure. All the validation procedures were based on multi-folds tests so to evaluate and compare the reliability of the fitting, the prediction skill, the coherence in the predictor selection and the precision of the susceptibility estimates. All the obtained models for the two methods produced very high predictive performances, with a general congruence between BLR and BRT in the predictor importance. In particular, the research highlighted that BRT-models reached a higher prediction performance with respect to BLR-models, for RP based modelling, whilst for the SP-based models the difference in predictive skills between the two methods dropped drastically, converging to an analogous excellent performance. However, when looking at the precision of the probability estimates, BLR demonstrated to produce more robust models in terms of selected predictors and coefficients, as well as of dispersion of the estimated probabilities around the mean value for each mapped pixel. The difference in the behaviour could be interpreted as the result of overfitting effects, which heavily affect decision tree classification more than logistic regression techniques.

Modelling of binary logistic regression for obesity among secondary students in a rural area of Kedah

NASA Astrophysics Data System (ADS)

Kamaruddin, Ainur Amira; Ali, Zalila; Noor, Norlida Mohd.; Baharum, Adam; Ahmad, Wan Muhamad Amir W.

2014-07-01

Logistic regression analysis examines the influence of various factors on a dichotomous outcome by estimating the probability of the event's occurrence. Logistic regression, also called a logit model, is a statistical procedure used to model dichotomous outcomes. In the logit model the log odds of the dichotomous outcome is modeled as a linear combination of the predictor variables. The log odds ratio in logistic regression provides a description of the probabilistic relationship of the variables and the outcome. In conducting logistic regression, selection procedures are used in selecting important predictor variables, diagnostics are used to check that assumptions are valid which include independence of errors, linearity in the logit for continuous variables, absence of multicollinearity, and lack of strongly influential outliers and a test statistic is calculated to determine the aptness of the model. This study used the binary logistic regression model to investigate overweight and obesity among rural secondary school students on the basis of their demographics profile, medical history, diet and lifestyle. The results indicate that overweight and obesity of students are influenced by obesity in family and the interaction between a student's ethnicity and routine meals intake. The odds of a student being overweight and obese are higher for a student having a family history of obesity and for a non-Malay student who frequently takes routine meals as compared to a Malay student.

Electronic health record analysis via deep poisson factor models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henao, Ricardo; Lu, James T.; Lucas, Joseph E.

Electronic Health Record (EHR) phenotyping utilizes patient data captured through normal medical practice, to identify features that may represent computational medical phenotypes. These features may be used to identify at-risk patients and improve prediction of patient morbidity and mortality. We present a novel deep multi-modality architecture for EHR analysis (applicable to joint analysis of multiple forms of EHR data), based on Poisson Factor Analysis (PFA) modules. Each modality, composed of observed counts, is represented as a Poisson distribution, parameterized in terms of hidden binary units. In-formation from different modalities is shared via a deep hierarchy of common hidden units. Activationmore » of these binary units occurs with probability characterized as Bernoulli-Poisson link functions, instead of more traditional logistic link functions. In addition, we demon-strate that PFA modules can be adapted to discriminative modalities. To compute model parameters, we derive efficient Markov Chain Monte Carlo (MCMC) inference that scales efficiently, with significant computational gains when compared to related models based on logistic link functions. To explore the utility of these models, we apply them to a subset of patients from the Duke-Durham patient cohort. We identified a cohort of over 12,000 patients with Type 2 Diabetes Mellitus (T2DM) based on diagnosis codes and laboratory tests out of our patient population of over 240,000. Examining the common hidden units uniting the PFA modules, we identify patient features that represent medical concepts. Experiments indicate that our learned features are better able to predict mortality and morbidity than clinical features identified previously in a large-scale clinical trial.« less

[Developing a predictive model for the caregiver strain index].

PubMed

Álvarez-Tello, Margarita; Casado-Mejía, Rosa; Praena-Fernández, Juan Manuel; Ortega-Calvo, Manuel

Patient homecare with multiple morbidities is an increasingly common occurrence. The caregiver strain index is tool in the form of questionnaire that is designed to measure the perceived burden of those who care for their families. The aim of this study is to construct a diagnostic nomogram of informal caregiver burden using data from a predictive model. The model was drawn up using binary logistic regression and the questionnaire items as dichotomous factors. The dependent variable was the final score obtained with the questionnaire but categorised in accordance with that in the literature. Scores between 0 and 6 were labelled as "no" (no caregiver stress) and at or greater than 7 as "yes". The version 3.1.1R statistical software was used. To construct confidence intervals for the ROC curve 2000 boot strap replicates were used. A sample of 67 caregivers was obtained. A diagnosing nomogram was made up with its calibration graph (Brier scaled = 0.686, Nagelkerke R 2 =0.791), and the corresponding ROC curve (area under the curve=0.962). The predictive model generated using binary logistic regression and the nomogram contain four items (1, 4, 5 and 9) of the questionnaire. R plotting functions allow a very good solution for validating a model like this. The area under the ROC curve (0.96; 95% CI: 0.994-0.941) achieves a high discriminative value. Calibration also shows high goodness of fit values, suggesting that it may be clinically useful in community nursing and geriatric establishments. Copyright © 2015 SEGG. Publicado por Elsevier España, S.L.U. All rights reserved.

Electronic health record analysis via deep poisson factor models

DOE PAGES

Henao, Ricardo; Lu, James T.; Lucas, Joseph E.; ...

2016-01-01

Electronic Health Record (EHR) phenotyping utilizes patient data captured through normal medical practice, to identify features that may represent computational medical phenotypes. These features may be used to identify at-risk patients and improve prediction of patient morbidity and mortality. We present a novel deep multi-modality architecture for EHR analysis (applicable to joint analysis of multiple forms of EHR data), based on Poisson Factor Analysis (PFA) modules. Each modality, composed of observed counts, is represented as a Poisson distribution, parameterized in terms of hidden binary units. In-formation from different modalities is shared via a deep hierarchy of common hidden units. Activationmore » of these binary units occurs with probability characterized as Bernoulli-Poisson link functions, instead of more traditional logistic link functions. In addition, we demon-strate that PFA modules can be adapted to discriminative modalities. To compute model parameters, we derive efficient Markov Chain Monte Carlo (MCMC) inference that scales efficiently, with significant computational gains when compared to related models based on logistic link functions. To explore the utility of these models, we apply them to a subset of patients from the Duke-Durham patient cohort. We identified a cohort of over 12,000 patients with Type 2 Diabetes Mellitus (T2DM) based on diagnosis codes and laboratory tests out of our patient population of over 240,000. Examining the common hidden units uniting the PFA modules, we identify patient features that represent medical concepts. Experiments indicate that our learned features are better able to predict mortality and morbidity than clinical features identified previously in a large-scale clinical trial.« less

Relationship between postoperative lung atelectasis and position of the endotracheal tube in pediatric living-donor liver transplantation.

PubMed

Lee, H-Y; Lu, C-H; Lu, H-F; Chen, C-L; Wang, C-H; Cheng, K-W; Wu, S-C; Jawan, B; Huang, C-J

2012-05-01

The aims of current study were: 1) to evaluate the incidence of lung atelectasis; and 2) to investigate whether or not the position of the endotracheal (ET) tube is associated with this complication. The medical records and chest roentgenograms of 183 pediatric patients who underwent living-donor liver transplantation were retrospectively reviewed and analyzed. Patients without atelectasis were grouped in group I (GI) and those with atelectasis in group II (GII). The patients' characteristics and ET tube level between groups were compared with unpaired Student's t test. Multiple binary logistic regressions were also performed to identify the important risk factors associated with lung atelectasis. Right upper lung (RUL) atelectsis could be found in ET tube at any level from T1 to T5, with incidence rates of 12.7%, 15.2%, 26.3%, 6.7%, and 100% for T1, T2, T3, T4, and T5, respectively. The incidence of atelectasis is 16.6%, and all of the atelectasis occurred in the RUL. No significant difference between groups was observed in the patients' characteristics, except for the amount of preoperative ascites. The likelihood of this risk factor could not be confirmed by multivariate binary logistic regression analysis. The incidence of lung atelectasis in our study was 16.6%, which all occurred in the RUL. No predictive risk factor from the patients' characteristics could be found, and no correlation between the level of the ET tube and the occurrence of RUL atelectasis could be observed. Copyright © 2012 Elsevier Inc. All rights reserved.

A VLT/NACO survey for triple and quadruple systems among visual pre-main sequence binaries

NASA Astrophysics Data System (ADS)

Correia, S.; Zinnecker, H.; Ratzka, Th.; Sterzik, M. F.

2006-12-01

Aims.This paper describes a systematic search for high-order multiplicity among wide visual Pre-Main Sequence (PMS) binaries. Methods: .We conducted an Adaptive Optics survey of a sample of 58 PMS wide binaries from various star-forming regions, which include 52 T Tauri systems with mostly K- and M-type primaries, with the NIR instrument NACO at the VLT. Results: .Of these 52 systems, 7 are found to be triple (2 new) and 7 quadruple (1 new). The new close companions are most likely physically bound based on their probability of chance projection and, for some of them, on their position on a color-color diagram. The corresponding degree of multiplicity among wide binaries (number of triples and quadruples divided by the number of systems) is 26.9 ± 7.2% in the projected separation range ~0.07 arcsec -12'', with the largest contribution from the Taurus-Auriga cloud. We also found that this degree of multiplicity is twice in Taurus compared to Ophiuchus and Chamaeleon for which the same number of sources are present in our sample. Considering a restricted sample composed of systems at distance 140-190 pc, the degree of multiplicity is 26.8 ± 8.1%, in the separation range 10/14 AU-1700/2300 AU (30 binaries, 5 triples, 6 quadruples). The observed frequency agrees with results from previous multiplicity surveys within the uncertainties, although a significant overabundance of quadruple systems compared to triple systems is apparent. Tentatively including the spectroscopic pairs in our restricted sample and comparing the multiplicity fractions to those measured for solar-type main-sequence stars in the solar neighborhood leads to the conclusion that both the ratio of triples to binaries and the ratio of quadruples to triples seems to be in excess among young stars. Most of the current numerical simulations of multiple star formation, and especially smoothed particles hydrodynamics simulations, over-predict the fraction of high-order multiplicity when compared to our results. The circumstellar properties around the individual components of our high-order multiple systems tend to favor mixed systems (i.e. systems including components of wTTS and cTTS type), which is in general agreement with previous studies of disks in binaries, with the exception of Taurus, where we find a preponderance of similar type of components among the multiples studied.

Examining Measurement Invariance and Differential Item Functioning with Discrete Latent Construct Indicators: A Note on a Multiple Testing Procedure

ERIC Educational Resources Information Center

Raykov, Tenko; Dimitrov, Dimiter M.; Marcoulides, George A.; Li, Tatyana; Menold, Natalja

2018-01-01

A latent variable modeling method for studying measurement invariance when evaluating latent constructs with multiple binary or binary scored items with no guessing is outlined. The approach extends the continuous indicator procedure described by Raykov and colleagues, utilizes similarly the false discovery rate approach to multiple testing, and…

Close Binaries in the Orion Nebula Cluster: On the Universality of Stellar Multiplicity and the Origin of Field Stars

NASA Astrophysics Data System (ADS)

Duchene, Gaspard; Lacour, Sylvestre; Moraux, Estelle; Bouvier, Jerome; Goodwin, Simon

2018-01-01

While stellar multiplicity is an ubiquitous outcome of star formation, there is a clear dichotomy between the multiplicity properties of young (~1 Myr-old) stellar clusters, like the ONC, which host a mostly field-like population of visual binaries, and those of equally young sparse populations, like the Taurus-Auriga region, which host twice as many stellar companions. Two distinct scenarios can account for this observation: one in which different star-forming regions form different number of stars, and one in which multiplicity properties are universal at birth but where internal cluster dynamics destroy many wide binaries. To solve this ambiguity, one must probe binaries that are sufficiently close so as not to be destroyed through interactions with other cluster members. To this end, we have conducted a survey for 10-100 au binaries in the ONC using the aperture masking technique with the VLT adaptive optics system. Among our sample of the 42 ONC members, we discovered 13 companions in this range of projected separations. This is consistent with the companion frequency observed in the Taurus population and twice as high as that observed among field stars. This survey thus strongly supports the idea that stellar multiplicity is characterized by near-universal initial properties that can later be dynamically altered. On the other hand, this exacerbates the question of the origin of field stars, since only clusters much denser than the ONC can effectively destroyed binaries closer than 100 au.

Air pollution by particulate matter PM10 may trigger multiple sclerosis relapses.

PubMed

Roux, Jonathan; Bard, Denis; Le Pabic, Estelle; Segala, Claire; Reis, Jacques; Ongagna, Jean-Claude; de Sèze, Jérôme; Leray, Emmanuelle

2017-07-01

Seasonal variation of relapses in multiple sclerosis (MS) suggests that season-dependent factors, such as ambient air pollution, may trigger them. However, only few studies have considered possible role of air pollutants as relapse's risk factor. We investigated the effect of particulate matter of aerodynamic diameter smaller than 10µm (PM 10 ) on MS relapses. In total, 536 relapsing MS patients from Strasbourg city (France) were included, accounting for 2052 relapses over 2000-2009 period. A case-crossover design was used with cases defined as the days of relapse and controls being selected in the same patient at plus and minus 35 days. Different lags from 0 to 30 days were considered. Conditional logistic regressions, adjusted on meteorological parameters, school and public holidays, were used and exposure was considered first as a quantitative variable and second, as a binary variable. The natural logarithm of the average PM 10 concentration lagged from 1 to 3 days before relapse onset was significantly associated with relapse risk (OR =1.40 [95% confidence interval 1.08-1.81]) in cold season. Consistent results were observed when considering PM 10 as a binary variable, even if not significant. With an appropriate study design and robust ascertainment of neurological events and exposure, the present study highlights the effect of PM 10 on the risk of relapse in MS patients, probably through oxidative stress mechanisms. Copyright © 2017 Elsevier Inc. All rights reserved.

Life and light: exotic photosynthesis in binary and multiple-star systems.

PubMed

O'Malley-James, J T; Raven, J A; Cockell, C S; Greaves, J S

2012-02-01

The potential for Earth-like planets within binary/multiple-star systems to host photosynthetic life was evaluated by modeling the levels of photosynthetically active radiation (PAR) such planets receive. Combinations of M and G stars in (i) close-binary systems; (ii) wide-binary systems, and (iii) three-star systems were investigated, and a range of stable radiation environments were found to be possible. These environmental conditions allow for the possibility of familiar, but also more exotic, forms of photosynthetic life, such as IR photosynthesizers and organisms that are specialized for specific spectral niches.

Are Binary Separations related to their System Mass?

NASA Astrophysics Data System (ADS)

Sterzik, M. F.; Durisen, R. H.

2004-08-01

We compile most recent multiplicity fractions and binary separation distributions for different primary masses, including very low-mass and brown dwarf primaries, and compare them with dynamical decay models of small-N clusters. The model predictions are based on detailed numerical calculations of the internal cluster dynamics, as well as on Monte-Carlo methods. Both observations and models reflect the same trends: (1) The multiplicity fraction is an increasing function of the primary mass. (2) The mean binary separations are increasing with the system mass in the sense that very low-mass binaries have average separations around ≈ 4AU, while the binary separation distribution for solar-type primaries peaks at ≈ 40AU. M-type binary systems apparently preferentially populate intermediate separations. Similar specific energy at the time of cluster formation for all cluster masses can possibly explain this trend.

More caregiving, less working: caregiving roles and gender difference.

PubMed

Lee, Yeonjung; Tang, Fengyan

2015-06-01

This study examined the relationship of caregiving roles to labor force participation using the nationally representative data from the Health and Retirement Study. The sample was composed of men and women aged 50 to 61 years (N = 5,119). Caregiving roles included caregiving for spouse, parents, and grandchildren; a summary of three caregiving roles was used to indicate multiple caregiving roles. Bivariate analysis using chi-square and t tests and binary logistic regression models were applied. Results show that women caregivers for parents and/or grandchildren were less likely to be in the labor force than non-caregivers and that caregiving responsibility was not related to labor force participation for the sample of men. Findings have implication for supporting family caregivers, especially women, to balance work and caregiving commitments. © The Author(s) 2013.

Covariate Imbalance and Adjustment for Logistic Regression Analysis of Clinical Trial Data

PubMed Central

Ciolino, Jody D.; Martin, Reneé H.; Zhao, Wenle; Jauch, Edward C.; Hill, Michael D.; Palesch, Yuko Y.

2014-01-01

In logistic regression analysis for binary clinical trial data, adjusted treatment effect estimates are often not equivalent to unadjusted estimates in the presence of influential covariates. This paper uses simulation to quantify the benefit of covariate adjustment in logistic regression. However, International Conference on Harmonization guidelines suggest that covariate adjustment be pre-specified. Unplanned adjusted analyses should be considered secondary. Results suggest that that if adjustment is not possible or unplanned in a logistic setting, balance in continuous covariates can alleviate some (but never all) of the shortcomings of unadjusted analyses. The case of log binomial regression is also explored. PMID:24138438

Binary versus non-binary information in real time series: empirical results and maximum-entropy matrix models

NASA Astrophysics Data System (ADS)

Almog, Assaf; Garlaschelli, Diego

2014-09-01

The dynamics of complex systems, from financial markets to the brain, can be monitored in terms of multiple time series of activity of the constituent units, such as stocks or neurons, respectively. While the main focus of time series analysis is on the magnitude of temporal increments, a significant piece of information is encoded into the binary projection (i.e. the sign) of such increments. In this paper we provide further evidence of this by showing strong nonlinear relations between binary and non-binary properties of financial time series. These relations are a novel quantification of the fact that extreme price increments occur more often when most stocks move in the same direction. We then introduce an information-theoretic approach to the analysis of the binary signature of single and multiple time series. Through the definition of maximum-entropy ensembles of binary matrices and their mapping to spin models in statistical physics, we quantify the information encoded into the simplest binary properties of real time series and identify the most informative property given a set of measurements. Our formalism is able to accurately replicate, and mathematically characterize, the observed binary/non-binary relations. We also obtain a phase diagram allowing us to identify, based only on the instantaneous aggregate return of a set of multiple time series, a regime where the so-called ‘market mode’ has an optimal interpretation in terms of collective (endogenous) effects, a regime where it is parsimoniously explained by pure noise, and a regime where it can be regarded as a combination of endogenous and exogenous factors. Our approach allows us to connect spin models, simple stochastic processes, and ensembles of time series inferred from partial information.

Population trends of binary near-Earth asteroids based on radar and lightcurves observations

NASA Astrophysics Data System (ADS)

Brozovic, Marina; Benner, Lance A. M.; Naidu, Shantanu P.; Taylor, Patrick A.; Busch, Michael W.; Margot, Jean-Luc; Nolan, Michael C.; Howell, Ellen S.; Springmann, Alessondra; Giorgini, Jon D.; Shepard, Michael K.; Magri, Christopher; Richardson, James E.; Rivera-Valentin, Edgard G.; Rodriguez-Ford, Linda A.; Zambrano Marin, Luisa Fernanda

2016-10-01

The Arecibo and Goldstone planetary radars are invaluable instruments for the discovery and characterization of binary and triple asteroids in the near-Earth asteroid (NEA) population. To date, 41 out of 56 known binaries and triples (~73% of the objects) have been discovered by radar and 49 of these multiple systems have been detected by radar. Their absolute magnitudes range from 12.4 for (1866) Sisyphus to 22.6 for 2015 TD144 and have a mean and rms dispersion of 18.1+-2.0. There is a pronounced decrease in the abundance of binaries for absolute magnitudes H>20. One of the smallest binaries, 1994 CJ1, with an absolute magnitude H=21.4, is also the most accessible binary for a spacecraft rendezvous. Among 365 NEAs with H<22 (corresponding to diameters larger than ~ 140 m) detected by radar since 1999, ~13% have at least one companion. Two triple systems are known, (15391) 2001 SN263 and (136617) 1994 CC, but this is probably an underestimate due to low signal to noise ratios (SNRs) for many of the binary radar detections. Taxonomic classes have been reported for 41 out of 56 currently known multiple systems and some trends are starting to emerge: at least 50% of multiple asteroid systems are S, Sq, Q, or Sk, and at least 20% are optically dark (C, B, P, or U). Thirteen V-class NEAs have been observed by radar and six of them are binaries. Curiously, a comparable number of E-class objects have been detected by radar, but none is known to be a binary.

Modelling the growth kinetics of Kocuria marina DAGII as a function of single and binary substrate during batch production of β-Cryptoxanthin.

PubMed

Mitra, Ruchira; Chaudhuri, Surabhi; Dutta, Debjani

2017-01-01

In the present investigation, growth kinetics of Kocuria marina DAGII during batch production of β-Cryptoxanthin (β-CRX) was studied by considering the effect of glucose and maltose as a single and binary substrate. The importance of mixed substrate over single substrate has been emphasised in the present study. Different mathematical models namely, the Logistic model for cell growth, the Logistic mass balance equation for substrate consumption and the Luedeking-Piret model for β-CRX production were successfully implemented. Model-based analyses for the single substrate experiments suggested that the concentrations of glucose and maltose higher than 7.5 and 10.0 g/L, respectively, inhibited the growth and β-CRX production by K. marina DAGII. The Han and Levenspiel model and the Luong product inhibition model accurately described the cell growth in glucose and maltose substrate systems with a R 2 value of 0.9989 and 0.9998, respectively. The effect of glucose and maltose as binary substrate was further investigated. The binary substrate kinetics was well described using the sum-kinetics with interaction parameters model. The results of production kinetics revealed that the presence of binary substrate in the cultivation medium increased the biomass and β-CRX yield significantly. This study is a first time detailed investigation on kinetic behaviours of K. marina DAGII during β-CRX production. The parameters obtained in the study might be helpful for developing strategies for commercial production of β-CRX by K. marina DAGII.

Modelling Status Food Security Households Disease Sufferers Pulmonary Tuberculosis Uses the Method Regression Logistics Binary

NASA Astrophysics Data System (ADS)

Wulandari, S. P.; Salamah, M.; Rositawati, A. F. D.

2018-04-01

Food security is the condition where the food fulfilment is managed well for the country till the individual. Indonesia is one of the country which has the commitment to create the food security becomes main priority. However, the food necessity becomes common thing means that it doesn’t care about nutrient standard and the health condition of family member, so in the fulfilment of food necessity also has to consider the disease suffered by the family member, one of them is pulmonary tuberculosa. From that reasons, this research is conducted to know the factors which influence on household food security status which suffered from pulmonary tuberculosis in the coastal area of Surabaya by using binary logistic regression method. The analysis result by using binary logistic regression shows that the variables wife latest education, house density and spacious house ventilation significantly affect on household food security status which suffered from pulmonary tuberculosis in the coastal area of Surabaya, where the wife education level is University/equivalent, the house density is eligible or 8 m2/person and spacious house ventilation 10% of the floor area has the opportunity to become food secure households amounted to 0.911089. While the chance of becoming food insecure households amounted to 0.088911. The model household food security status which suffered from pulmonary tuberculosis in the coastal area of Surabaya has been conformable, and the overall percentages of those classifications are at 71.8%.

Binary Logistic Regression Analysis for Detecting Differential Item Functioning: Effectiveness of R[superscript 2] and Delta Log Odds Ratio Effect Size Measures

ERIC Educational Resources Information Center

Hidalgo, Mª Dolores; Gómez-Benito, Juana; Zumbo, Bruno D.

2014-01-01

The authors analyze the effectiveness of the R[superscript 2] and delta log odds ratio effect size measures when using logistic regression analysis to detect differential item functioning (DIF) in dichotomous items. A simulation study was carried out, and the Type I error rate and power estimates under conditions in which only statistical testing…

Logits and Tigers and Bears, Oh My! A Brief Look at the Simple Math of Logistic Regression and How It Can Improve Dissemination of Results

ERIC Educational Resources Information Center

Osborne, Jason W.

2012-01-01

Logistic regression is slowly gaining acceptance in the social sciences, and fills an important niche in the researcher's toolkit: being able to predict important outcomes that are not continuous in nature. While OLS regression is a valuable tool, it cannot routinely be used to predict outcomes that are binary or categorical in nature. These…

Binary catalogue of exoplanets

NASA Astrophysics Data System (ADS)

Schwarz, Richard; Bazso, Akos; Zechner, Renate; Funk, Barbara

2016-02-01

Since 1995 there is a database which list most of the known exoplanets (The Extrasolar Planets Encyclopaedia at http://exoplanet.eu/). With the growing number of detected exoplanets in binary and multiple star systems it became more important to mark and to separate them into a new database, which is not available in the Extrasolar Planets Encyclopaedia. Therefore we established an online database (which can be found at: http://www.univie.ac.at/adg/schwarz/multiple.html) for all known exoplanets in binary star systems and in addition for multiple star systems, which will be updated regularly and linked to the Extrasolar Planets Encyclopaedia. The binary catalogue of exoplanets is available online as data file and can be used for statistical purposes. Our database is divided into two parts: the data of the stars and the planets, given in a separate list. We describe also the different parameters of the exoplanetary systems and present some applications.

Binary power multiplier for electromagnetic energy

DOEpatents

Farkas, Zoltan D.

1988-01-01

A technique for converting electromagnetic pulses to higher power amplitude and shorter duration, in binary multiples, splits an input pulse into two channels, and subjects the pulses in the two channels to a number of binary pulse compression operations. Each pulse compression operation entails combining the pulses in both input channels and selectively steering the combined power to one output channel during the leading half of the pulses and to the other output channel during the trailing half of the pulses, and then delaying the pulse in the first output channel by an amount equal to half the initial pulse duration. Apparatus for carrying out each of the binary multiplication operation preferably includes a four-port coupler (such as a 3 dB hybrid), which operates on power inputs at a pair of input ports by directing the combined power to either of a pair of output ports, depending on the relative phase of the inputs. Therefore, by appropriately phase coding the pulses prior to any of the pulse compression stages, the entire pulse compression (with associated binary power multiplication) can be carried out solely with passive elements.

Multiplicity of Massive Stars

NASA Astrophysics Data System (ADS)

Zinnecker, Hans

We review the multiplicity of massive stars by compiling the abstracts of the most relevant papers in the field. We start by discussing the massive stars in the Orion Trapezium Cluster and in other Galactic young clusters and OB associations, and end with the R136 cluster in the LMC. The multiplicity of field O-stars and runaway OB stars is also reviewed. The results of both visual and spectroscopic surveys are presented, as well as data for eclipsing systems. Among the latter, we find the most massive known binary system WR20a, with two ~,80M_⊙ components in a 3 day orbit. Some 80% of the wide visual binaries in stellar associations are in fact hierarchical triple systems, where typically the more massive of the binary components is itself a spectroscopic or even eclipsing binary pair. The multiplicity (number of companions) of massive star primaries is significantly higher than for low-mass solar-type primaries or for young low-mass T Tauri stars. There is also a striking preponderance of very close nearly equal mass binary systems (the origin of which has recently been explained in an accretion scenario). Finally, we offer a new idea as to the origin of massive Trapezium systems, frequently found in the centers of dense young clusters.

Physical and mental health status of survivors of multiple cancer diagnoses: findings from the National Health Interview Survey.

PubMed

Andrykowski, Michael A

2012-07-15

Little research has identified the physical and mental health status of survivors of multiple primary cancer diagnoses. By using data from the population-based 2009 National Health Information Survey, 154 survivors of multiple primary cancer diagnoses, 1427 survivors of a single cancer diagnosis, and 25,004 individuals without a history of cancer diagnosis were identified. The multiple cancer group was compared with the single cancer and no cancer groups with regard to physical and mental health status using analysis of covariance and binary logistic regression. Relative to the no cancer group, the multiple cancer group reported significantly poorer mental health status, greater lifetime, recent, and current prevalence of a variety of medical conditions and comorbidities, and more health-related disability. Although observed group differences between the multiple cancer and single cancer groups were less pronounced than those between the multiple cancer and no cancer groups, a consistent pattern was also evident; the multiple cancer group reported significantly poorer status relative to the single cancer group across a range of mental and physical health and illness-related disability indices. Diagnosis of 2 or more primary cancers (excluding nonmelanoma skin cancers) is associated with increased risk for poorer physical and mental health status over and above that associated with diagnosis of a single primary cancer. Survivors of multiple and single primary cancer diagnoses should be considered as distinct subgroups, and increased attention should be devoted to the unique status and needs of survivors of multiple primary cancer diagnoses. Copyright © 2011 American Cancer Society.

Not Alone: Tracing the Origins of Very-Low-Mass Stars and Brown Dwarfs Through Multiplicity Studies

NASA Astrophysics Data System (ADS)

Burgasser, A. J.; Reid, I. N.; Siegler, N.; Close, L.; Allen, P.; Lowrance, P.; Gizis, J.

The properties of multiple stellar systems have long provided important empirical constraints for star-formation theories, enabling (along with several other lines of evidence) a concrete, qualitative picture of the birth and early evolution of normal stars. At very low masses (VLM; M ? 0.1 solar mass), down to and below the hydrogen-burning minimum mass, our understanding of formation processes is not as clear, with several competing theories now under consideration. One means of testing these theories is through the empirical characterization of VLM multiple systems. Here, we review the results of various VLM multiplicity studies to date. These systems can be generally characterized as closely separated (93% have projected separations ? < 20 AU), near equal-mass (77% have M2/M1 ? 0.8) and occurring infrequently (perhaps 10-30% of systems are binary). Both the frequency and maximum separation of stellar and brown dwarf binaries steadily decrease for lower system masses, suggesting that VLM binary formation and/or evolution may be a mass-dependent process. There is evidence for a fairly rapid decline in the number of loosely bound systems below ~0.3 solar mass, corresponding to a factor of 10-20 increase in the minimum binding energy of VLM binaries as compared to more massive stellar binaries. This wide-separation "desert" is present among both field (~1-5 G.y.) and older (>100 m.y.) cluster systems, while the youngest (<10 m.y.) VLM binaries, particularly those in nearby, low-density star-forming regions, appear to have somewhat different systemic properties. We compare these empirical trends to predictions laid out by current formation theories, and outline future observational studies needed to probe the full parameter space of the lowest-mass multiple systems.

Candidates of eclipsing multiples based on extraneous eclipses on binary light curves: KIC 7622486, KIC 7668648, KIC 7670485 and KIC 8938628

NASA Astrophysics Data System (ADS)

Zhang, Jia; Qian, Sheng-Bang; He, Jian-Duo

2017-02-01

Four candidates of eclipsing multiples, based on new extraneous eclipses found on Kepler binary light curves, are presented and studied. KIC 7622486 is a double eclipsing binary candidate with orbital periods of 2.2799960 d and 40.246503 d. The two binary systems do not eclipse each other in the line of sight, but there is mutual gravitational influence between them which leads to the small but definite eccentricity of 0.0035(0.0022) associated with the short 2.2799960 d period orbit. KIC 7668648 is a hierarchical quadruple system candidate, with two sets of solid 203 ± 5 d period extraneous eclipses and another independent set of extraneous eclipses. A clear and credible extraneous eclipse is found on the binary light curve of KIC 7670485 which makes it a triple system candidate. Two sets of extraneous eclipses with periods of about 390 d and 220 d are found on KIC 8938628 binary curves, which not only confirm the previous conclusion of the 388.5 ± 0.3 triple system, but also indicate new additional objects that make KIC 8938628 a hierarchical quadruple system candidate. The results from these four candidates will contribute to the field of eclipsing multiples.

Contributions of sociodemographic factors to criminal behavior

PubMed Central

Mundia, Lawrence; Matzin, Rohani; Mahalle, Salwa; Hamid, Malai Hayati; Osman, Ratna Suriani

2016-01-01

We explored the extent to which prisoner sociodemographic variables (age, education, marital status, employment, and whether their parents were married or not) influenced offending in 64 randomly selected Brunei inmates, comprising both sexes. A quantitative field survey design ideal for the type of participants used in a prison context was employed to investigate the problem. Hierarchical multiple regression analysis with backward elimination identified prisoner marital status and age groups as significantly related to offending. Furthermore, hierarchical multinomial logistic regression analysis with backward elimination indicated that prisoners’ age, primary level education, marital status, employment status, and parental marital status as significantly related to stealing offenses with high odds ratios. All 29 nonrecidivists were false negatives and predicted to reoffend upon release. Similarly, all 33 recidivists were projected to reoffend after release. Hierarchical binary logistic regression analysis revealed age groups (24–29 years and 30–35 years), employed prisoner, and primary level education as variables with high likelihood trends for reoffending. The results suggested that prisoner interventions (educational, counseling, and psychotherapy) in Brunei should treat not only antisocial personality, psychopathy, and mental health problems but also sociodemographic factors. The study generated offending patterns, trends, and norms that may inform subsequent investigations on Brunei prisoners. PMID:27382342

Biomarker combinations for diagnosis and prognosis in multicenter studies: Principles and methods.

PubMed

Meisner, Allison; Parikh, Chirag R; Kerr, Kathleen F

2017-01-01

Many investigators are interested in combining biomarkers to predict a binary outcome or detect underlying disease. This endeavor is complicated by the fact that many biomarker studies involve data from multiple centers. Depending upon the relationship between center, the biomarkers, and the target of prediction, care must be taken when constructing and evaluating combinations of biomarkers. We introduce a taxonomy to describe the role of center and consider how a biomarker combination should be constructed and evaluated. We show that ignoring center, which is frequently done by clinical researchers, is often not appropriate. The limited statistical literature proposes using random intercept logistic regression models, an approach that we demonstrate is generally inadequate and may be misleading. We instead propose using fixed intercept logistic regression, which appropriately accounts for center without relying on untenable assumptions. After constructing the biomarker combination, we recommend using performance measures that account for the multicenter nature of the data, namely the center-adjusted area under the receiver operating characteristic curve. We apply these methods to data from a multicenter study of acute kidney injury after cardiac surgery. Appropriately accounting for center, both in construction and evaluation, may increase the likelihood of identifying clinically useful biomarker combinations.

Work related complaints of neck, shoulder and arm among computer office workers: a cross-sectional evaluation of prevalence and risk factors in a developing country.

PubMed

Ranasinghe, Priyanga; Perera, Yashasvi S; Lamabadusuriya, Dilusha A; Kulatunga, Supun; Jayawardana, Naveen; Rajapakse, Senaka; Katulanda, Prasad

2011-08-04

Complaints of arms, neck and shoulders (CANS) is common among computer office workers. We evaluated an aetiological model with physical/psychosocial risk-factors. We invited 2,500 computer office workers for the study. Data on prevalence and risk-factors of CANS were collected by validated Maastricht-Upper-extremity-Questionnaire. Workstations were evaluated by Occupational Safety and Health Administration (OSHA) Visual-Display-Terminal workstation-checklist. Participants' knowledge and awareness was evaluated by a set of expert-validated questions. A binary logistic regression analysis investigated relationships/correlations between risk-factors and symptoms. Sample size was 2,210. Mean age 30.8 ± 8.1 years, 50.8% were males. The 1-year prevalence of CANS was 56.9%, commonest region of complaint was forearm/hand (42.6%), followed by neck (36.7%) and shoulder/arm (32.0%). In those with CANS, 22.7% had taken treatment from a health care professional, only in 1.1% seeking medical advice an occupation-related injury had been suspected/diagnosed. In addition 9.3% reported CANS-related absenteeism from work, while 15.4% reported CANS causing disruption of normal activities. A majority of evaluated workstations in all participants (88.4%,) and in those with CANS (91.9%) had OSHA non-compliant workstations. In the binary logistic regression analyses female gender, daily computer usage, incorrect body posture, bad work-habits, work overload, poor social support and poor ergonomic knowledge were associated with CANS and its' severity In a multiple logistic regression analysis controlling for age, gender and duration of occupation, incorrect body posture, bad work-habits and daily computer usage were significant independent predictors of CANS. The prevalence of work-related CANS among computer office workers in Sri Lanka, a developing, South Asian country is high and comparable to prevalence in developed countries. Work-related physical factors, psychosocial factors and lack of awareness were all important associations of CANS and effective preventive strategies need to address all three areas.

Commission 42: Close Binary Stars

NASA Astrophysics Data System (ADS)

Rucinski, Slavek M.; Ribas, Ignasi; Giménez, Alvaro; Harmanec, Petr; Hilditch, Ronald W.; Kaluzny, Janusz; Niarchos, Panayiotis; Nordström, Birgitta; Oláh, Katalin; Richards, Mercedes T.; Scarfe, Colin D.; Sion, Edward M.; Torres, Guillermo; Vrielmann, Sonja

Two meetings of interest to close binaries took place during the reporting period: A full day session on short-period binary stars mostly CV's (Milone et al. 2008) during the 2006 AAS Spring meeting in Calgary and the very broadly designed IAU Symposium No. 240 on Binary Stars as Critical Tools and Tests in Contemporary Astrophysics in Prague, 2006, with many papers on close binaries [Hartkopf et al. 2007]. In addition, the book by Eggleton (2006), which is a comprehensive summary of evolutionary processes in binary and multiple stars, was published.

Binary logistic regression modelling: Measuring the probability of relapse cases among drug addict

NASA Astrophysics Data System (ADS)

Ismail, Mohd Tahir; Alias, Siti Nor Shadila

2014-07-01

For many years Malaysia faced the drug addiction issues. The most serious case is relapse phenomenon among treated drug addict (drug addict who have under gone the rehabilitation programme at Narcotic Addiction Rehabilitation Centre, PUSPEN). Thus, the main objective of this study is to find the most significant factor that contributes to relapse to happen. The binary logistic regression analysis was employed to model the relationship between independent variables (predictors) and dependent variable. The dependent variable is the status of the drug addict either relapse, (Yes coded as 1) or not, (No coded as 0). Meanwhile the predictors involved are age, age at first taking drug, family history, education level, family crisis, community support and self motivation. The total of the sample is 200 which the data are provided by AADK (National Antidrug Agency). The finding of the study revealed that age and self motivation are statistically significant towards the relapse cases..

Use of antidementia drugs in frontotemporal lobar degeneration.

PubMed

López-Pousa, Secundino; Calvó-Perxas, Laia; Lejarreta, Saioa; Cullell, Marta; Meléndez, Rosa; Hernández, Erélido; Bisbe, Josep; Perkal, Héctor; Manzano, Anna; Roig, Anna Maria; Turró-Garriga, Oriol; Vilalta-Franch, Joan; Garre-Olmo, Josep

2012-06-01

Clinical evidence indicates that acetylcholinesterase inhibitors (AChEIs) are not efficacious to treat frontotemporal lobar degeneration (FTLD). The British Association for Psychopharmacology recommends avoiding the use of AChEI and memantine in patients with FTLD. Cross-sectional design using 1092 cases with Alzheimer's disease (AD) and 64 cases with FTLD registered by the Registry of Dementias of Girona. Bivariate analyses were performed, and binary logistic regressions were used to detect variables associated with antidementia drugs consumption. The AChEIs were consumed by 57.6% and 42.2% of the patients with AD and FTLD, respectively. Memantine was used by 17.2% and 10.9% of patients with AD and FTLD, respectively. Binary logistic regressions yielded no associations with antidementia drugs consumption. There is a discrepancy regarding clinical practice and the recommendations based upon clinical evidence. The increased central nervous system drug use detected in FTLD requires multicentric studies aiming at finding the best means to treat these patients.

Neurocognitive functioning in children with developmental dyslexia and attention-deficit/hyperactivity disorder: Multiple deficits and diagnostic accuracy.

PubMed

Moura, Octávio; Pereira, Marcelino; Alfaiate, Cláudia; Fernandes, Eva; Fernandes, Boavida; Nogueira, Susana; Moreno, Joana; Simões, Mário R

2017-04-01

This study aimed to investigate the neurocognitive functioning of children with developmental dyslexia (DD) and attention-deficit/hyperactivity disorder (ADHD). Four groups of children between the ages of 8 and 10 years participated in the study: typically developing children (TDC; N = 34), children with DD-only (N = 32), children with ADHD-only (N = 32), and children with DD+ADHD (N = 18). Children with DD and ADHD exhibited significant weaknesses on almost all neurocognitive measures compared with TDC. Large effect sizes were observed for naming speed and phonological awareness. The comorbid group showed deficits consistent with both DD and ADHD without additional impairments. Results from binary logistic regression and receiver-operating characteristic (ROC) curve analyses suggested that some neurocognitive measures revealed an adequate sensitivity for the clinical diagnosis of both neurodevelopmental disorders. Specifically, naming speed and phonological awareness were the strongest predictors to correctly discriminate both disorders. Taken together, the results lend support to the multiple cognitive deficit hypothesis showing a considerable overlap of neurocognitive deficits between both disorders.

Use of generalized ordered logistic regression for the analysis of multidrug resistance data.

PubMed

Agga, Getahun E; Scott, H Morgan

2015-10-01

Statistical analysis of antimicrobial resistance data largely focuses on individual antimicrobial's binary outcome (susceptible or resistant). However, bacteria are becoming increasingly multidrug resistant (MDR). Statistical analysis of MDR data is mostly descriptive often with tabular or graphical presentations. Here we report the applicability of generalized ordinal logistic regression model for the analysis of MDR data. A total of 1,152 Escherichia coli, isolated from the feces of weaned pigs experimentally supplemented with chlortetracycline (CTC) and copper, were tested for susceptibilities against 15 antimicrobials and were binary classified into resistant or susceptible. The 15 antimicrobial agents tested were grouped into eight different antimicrobial classes. We defined MDR as the number of antimicrobial classes to which E. coli isolates were resistant ranging from 0 to 8. Proportionality of the odds assumption of the ordinal logistic regression model was violated only for the effect of treatment period (pre-treatment, during-treatment and post-treatment); but not for the effect of CTC or copper supplementation. Subsequently, a partially constrained generalized ordinal logistic model was built that allows for the effect of treatment period to vary while constraining the effects of treatment (CTC and copper supplementation) to be constant across the levels of MDR classes. Copper (Proportional Odds Ratio [Prop OR]=1.03; 95% CI=0.73-1.47) and CTC (Prop OR=1.1; 95% CI=0.78-1.56) supplementation were not significantly associated with the level of MDR adjusted for the effect of treatment period. MDR generally declined over the trial period. In conclusion, generalized ordered logistic regression can be used for the analysis of ordinal data such as MDR data when the proportionality assumptions for ordered logistic regression are violated. Published by Elsevier B.V.

Continued Kinematic and Photometric Investigations of Hierarchical Solar-type Multiple Star Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberts, Lewis C. Jr.; Marinan, Anne D.; Tokovinin, Andrei

2017-03-01

We observed 15 of the solar-type binaries within 67 pc of the Sun previously observed by the Robo-AO system in the visible, with the PHARO near-infrared camera and the PALM-3000 adaptive optics system on the 5 m Hale telescope. The physical status of the binaries is confirmed through common proper motion and detection of orbital motion. In the process, we detected a new candidate companion to HIP 95309. We also resolved the primary of HIP 110626 into a close binary, making that system a triple. These detections increase the completeness of the multiplicity survey of the solar-type stars within 67more » pc of the Sun. Combining our observations of HIP 103455 with archival astrometric measurements and RV measurements, we are able to compute the first orbit of HIP 103455, showing that the binary has a 68 year period. We place the components on a color–magnitude diagram and discuss each multiple system individually.« less

Logistic regression for circular data

NASA Astrophysics Data System (ADS)

Al-Daffaie, Kadhem; Khan, Shahjahan

2017-05-01

This paper considers the relationship between a binary response and a circular predictor. It develops the logistic regression model by employing the linear-circular regression approach. The maximum likelihood method is used to estimate the parameters. The Newton-Raphson numerical method is used to find the estimated values of the parameters. A data set from weather records of Toowoomba city is analysed by the proposed methods. Moreover, a simulation study is considered. The R software is used for all computations and simulations.

Comparison of support vector machine classification to partial least squares dimension reduction with logistic descrimination of hyperspectral data

NASA Astrophysics Data System (ADS)

Wilson, Machelle; Ustin, Susan L.; Rocke, David

2003-03-01

Remote sensing technologies with high spatial and spectral resolution show a great deal of promise in addressing critical environmental monitoring issues, but the ability to analyze and interpret the data lags behind the technology. Robust analytical methods are required before the wealth of data available through remote sensing can be applied to a wide range of environmental problems for which remote detection is the best method. In this study we compare the classification effectiveness of two relatively new techniques on data consisting of leaf-level reflectance from plants that have been exposed to varying levels of heavy metal toxicity. If these methodologies work well on leaf-level data, then there is some hope that they will also work well on data from airborne and space-borne platforms. The classification methods compared were support vector machine classification of exposed and non-exposed plants based on the reflectance data, and partial east squares compression of the reflectance data followed by classification using logistic discrimination (PLS/LD). PLS/LD was performed in two ways. We used the continuous concentration data as the response during compression, and then used the binary response required during logistic discrimination. We also used a binary response during compression followed by logistic discrimination. The statistics we used to compare the effectiveness of the methodologies was the leave-one-out cross validation estimate of the prediction error.

Risk estimation using probability machines

PubMed Central

2014-01-01

Background Logistic regression has been the de facto, and often the only, model used in the description and analysis of relationships between a binary outcome and observed features. It is widely used to obtain the conditional probabilities of the outcome given predictors, as well as predictor effect size estimates using conditional odds ratios. Results We show how statistical learning machines for binary outcomes, provably consistent for the nonparametric regression problem, can be used to provide both consistent conditional probability estimation and conditional effect size estimates. Effect size estimates from learning machines leverage our understanding of counterfactual arguments central to the interpretation of such estimates. We show that, if the data generating model is logistic, we can recover accurate probability predictions and effect size estimates with nearly the same efficiency as a correct logistic model, both for main effects and interactions. We also propose a method using learning machines to scan for possible interaction effects quickly and efficiently. Simulations using random forest probability machines are presented. Conclusions The models we propose make no assumptions about the data structure, and capture the patterns in the data by just specifying the predictors involved and not any particular model structure. So they do not run the same risks of model mis-specification and the resultant estimation biases as a logistic model. This methodology, which we call a “risk machine”, will share properties from the statistical machine that it is derived from. PMID:24581306

Risk estimation using probability machines.

PubMed

Dasgupta, Abhijit; Szymczak, Silke; Moore, Jason H; Bailey-Wilson, Joan E; Malley, James D

2014-03-01

Logistic regression has been the de facto, and often the only, model used in the description and analysis of relationships between a binary outcome and observed features. It is widely used to obtain the conditional probabilities of the outcome given predictors, as well as predictor effect size estimates using conditional odds ratios. We show how statistical learning machines for binary outcomes, provably consistent for the nonparametric regression problem, can be used to provide both consistent conditional probability estimation and conditional effect size estimates. Effect size estimates from learning machines leverage our understanding of counterfactual arguments central to the interpretation of such estimates. We show that, if the data generating model is logistic, we can recover accurate probability predictions and effect size estimates with nearly the same efficiency as a correct logistic model, both for main effects and interactions. We also propose a method using learning machines to scan for possible interaction effects quickly and efficiently. Simulations using random forest probability machines are presented. The models we propose make no assumptions about the data structure, and capture the patterns in the data by just specifying the predictors involved and not any particular model structure. So they do not run the same risks of model mis-specification and the resultant estimation biases as a logistic model. This methodology, which we call a "risk machine", will share properties from the statistical machine that it is derived from.

MAPPING THE SHORES OF THE BROWN DWARF DESERT. II. MULTIPLE STAR FORMATION IN TAURUS-AURIGA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kraus, Adam L.; Ireland, Michael J.; Martinache, Frantz

2011-04-10

We have conducted a high-resolution imaging study of the Taurus-Auriga star-forming region in order to characterize the primordial outcome of multiple star formation and the extent of the brown dwarf desert. Our survey identified 16 new binary companions to primary stars with masses of 0.25-2.5 M{sub sun}, raising the total number of binary pairs (including components of high-order multiples) with separations of 3-5000 AU to 90. We find that {approx}2/3-3/4 of all Taurus members are multiple systems of two or more stars, while the other {approx}1/4-1/3 appear to have formed as single stars; the distribution of high-order multiplicity suggests thatmore » fragmentation into a wide binary has no impact on the subsequent probability that either component will fragment again. The separation distribution for solar-type stars (0.7-2.5 M{sub sun}) is nearly log-flat over separations of 3-5000 AU, but lower-mass stars (0.25-0.7 M{sub sun}) show a paucity of binary companions with separations of {approx}>200 AU. Across this full mass range, companion masses are well described with a linear-flat function; all system mass ratios (q = M{sub B} /M{sub A} ) are equally probable, apparently including substellar companions. Our results are broadly consistent with the two expected modes of binary formation (free-fall fragmentation on large scales and disk fragmentation on small scales), but the distributions provide some clues as to the epochs at which the companions are likely to form.« less

Multi-epoch observations with high spatial resolution of multiple T Tauri systems

NASA Astrophysics Data System (ADS)

Csépány, Gergely; van den Ancker, Mario; Ábrahám, Péter; Köhler, Rainer; Brandner, Wolfgang; Hormuth, Felix; Hiss, Hector

2017-07-01

Context. In multiple pre-main-sequence systems the lifetime of circumstellar discs appears to be shorter than around single stars, and the actual dissipation process may depend on the binary parameters of the systems. Aims: We report high spatial resolution observations of multiple T Tauri systems at optical and infrared wavelengths. We determine whether the components are gravitationally bound and orbital motion is visible, derive orbital parameters, and investigate possible correlations between the binary parameters and disc states. Methods: We selected 18 T Tau multiple systems (16 binary and two triple systems, yielding 16 + 2 × 2 = 20 binary pairs) in the Taurus-Auriga star-forming region from a previous survey, with spectral types from K1 to M5 and separations from 0.22″ (31 AU) to 5.8″ (814 AU). We analysed data acquired in 2006-07 at Calar Alto using the AstraLux lucky imaging system, along with data from SPHERE and NACO at the VLT, and from the literature. Results: We found ten pairs to orbit each other, five pairs that may show orbital motion, and five likely common proper motion pairs. We found no obvious correlation between the stellar parameters and binary configuration. The 10 μm infra-red excess varies between 0.1 and 7.2 mag (similar to the distribution in single stars, where it is between 1.7 and 9.1), implying that the presence of the binary star does not greatly influence the emission from the inner disc. Conclusions: We have detected orbital motion in young T Tauri systems over a timescale of ≈ 20 yr. Further observations with even longer temporal baseline will provide crucial information on the dynamics of these young stellar systems.

Multiplicity among Young Brown Dwarfs and Very Low Mass Stars

NASA Astrophysics Data System (ADS)

Ahmic, Mirza; Jayawardhana, Ray; Brandeker, Alexis; Scholz, Alexander; van Kerkwijk, Marten H.; Delgado-Donate, Eduardo; Froebrich, Dirk

2007-12-01

We report on a near-infrared adaptive optics imaging survey of 31 young brown dwarfs and very low mass (VLM) stars, 28 of which are in the Chamaeleon I star-forming region, using the ESO Very Large Telescope. We resolve the suspected 0.16'' (~26 AU) binary Cha Hα 2 and present two new binaries, Hn 13 and CHXR 15, with separations of 0.13'' (~20 AU) and 0.30'' (~50 AU), respectively; the latter is one of the widest VLM systems known. We find a binary frequency of 11+9-6%, thus confirming the trend for a lower binary frequency with decreasing mass. By combining our work with previous surveys, we arrive at the largest sample of young VLM objects (72) with high angular resolution imaging to date. Its multiplicity fraction is in statistical agreement with that for VLM objects in the field. Furthermore, we note that many field stellar binaries with lower binding energies and/or wider cross sections have survived dynamical evolution and that statistical models suggest tidal disruption by passing stars is unlikely to affect the binary properties of our systems. Thus, we argue that there is no significant evolution of multiplicity with age among brown dwarfs and VLM stars in OB and T associations between a few megayears to several gigayears. Instead, the observations so far suggest that VLM objects are either less likely to be born in fragile multiple systems than solar-mass stars or such systems are disrupted very early. We dedicate this paper to the memory of our coauthor, Eduardo Delgado-Donate, who died in a hiking accident in Tenerife earlier this year.

Negative Bystander Behavior in Bullying Dynamics: Assessing the Impact of Social Capital Deprivation and Anti-social Capital.

PubMed

Evans, Caroline B R; Smokowski, Paul R

2017-02-01

Bystanders witness bullying, but are not directly involved as a bully or victim; however, they often engage in negative bystander behavior. This study examines how social capital deprivation and anti-social capital are associated with the likelihood of engaging in negative bystander behavior in a sample (N = 5752) of racially/ethnically diverse rural youth. Data were collected using an online, youth self-report; the current study uses cross sectional data. Following multiple imputation, a binary logistic regression with robust standard errors was run. Results partially supported the hypothesis and indicated that social capital deprivation in the form of peer pressure and verbal victimization and anti-social capital in the form of delinquent friends, bullying perpetration, verbal perpetration, and physical perpetration were significantly associated with an increased likelihood of engaging in negative bystander behavior. Findings highlight the importance of establishing sources of positive social support for disenfranchised youth.

The Impact of Work and Volunteer Hours on the Health of Undergraduate Students.

PubMed

Lederer, Alyssa M; Autry, Dana M; Day, Carol R T; Oswalt, Sara B

2015-01-01

To examine the impact of work and volunteer hours on 4 health issues among undergraduate college students. Full-time undergraduate students (N = 70,068) enrolled at 129 institutions who participated in the Spring 2011 American College Health Association-National College Health Assessment II survey. Multiple linear regression and binary logistic regression were used to examine work and volunteer hour impact on depression, feelings of being overwhelmed, sleep, and physical activity. The impact of work and volunteer hours was inconsistent among the health outcomes. Increased work hours tended to negatively affect sleep and increase feelings of being overwhelmed. Students who volunteered were more likely to meet physical activity guidelines, and those who volunteered 1 to 9 hours per week reported less depression. College health professionals should consider integrating discussion of students' employment and volunteering and their intersection with health outcomes into clinical visits, programming, and other services.

Determinants of unprotected casual heterosexual sex in Ghana.

PubMed

Kumi-Kyereme, Akwasi; Tuoyire, Derek A; Darteh, Eugene K M

2014-05-01

Casual heterosexual sex remains a significant contributor to HIV transmissions in Ghana. The study used data from the 2008 Ghana Demographic and Health Survey (GDHS) to assess the socio-demographic, economic and spatial factors influencing unprotected casual heterosexual sex among men and women. The results of the binary logistic regression models revealed that women aged 35-44 had significantly higher odds of engaging in unprotected casual heterosexual sex than those aged 15-24, unlike the men. There were significantly lower odds of unprotected casual heterosexual sex for women and men with exposure to print media compared with those without exposure. Compared with men residing in the Western Region, unprotected casual heterosexual sex was significantly less likely among those in the Upper East Region. There is the need for behavioural change campaigns in Ghana that take into consideration the multiplicity of factors that determine unprotected casual heterosexual sex.

Do Concomitant Cranium and Axis Injuries Predict Worse Outcome? A Trauma Database Quantitative Analysis

PubMed Central

Chittiboina, Prashant; Banerjee, Anirban Deep; Nanda, Anil

2011-01-01

We performed a trauma database analysis to identify the effect of concomitant cranial injuries on outcome in patients with fractures of the axis. We identified patients with axis fractures over a 14-year period. A binary outcome measure was used. Univariate and multiple logistic regression analysis were performed. There were 259 cases with axis fractures. Closed head injury was noted in 57% and skull base trauma in 14%. Death occurred in 17 cases (6%). Seventy-two percent had good outcome. Presence of abnormal computed tomography head findings, skull base fractures, and visceral injury was significantly associated with poor outcome. Skull base injury in association with fractures of the axis is a significant independent predictor of worse outcomes, irrespective of the severity of the head injury. We propose that presence of concomitant cranial and upper vertebral injuries require careful evaluation in view of the associated poor prognosis. PMID:22470268

Introduction to the use of regression models in epidemiology.

PubMed

Bender, Ralf

2009-01-01

Regression modeling is one of the most important statistical techniques used in analytical epidemiology. By means of regression models the effect of one or several explanatory variables (e.g., exposures, subject characteristics, risk factors) on a response variable such as mortality or cancer can be investigated. From multiple regression models, adjusted effect estimates can be obtained that take the effect of potential confounders into account. Regression methods can be applied in all epidemiologic study designs so that they represent a universal tool for data analysis in epidemiology. Different kinds of regression models have been developed in dependence on the measurement scale of the response variable and the study design. The most important methods are linear regression for continuous outcomes, logistic regression for binary outcomes, Cox regression for time-to-event data, and Poisson regression for frequencies and rates. This chapter provides a nontechnical introduction to these regression models with illustrating examples from cancer research.

Controlled pattern imputation for sensitivity analysis of longitudinal binary and ordinal outcomes with nonignorable dropout.

PubMed

Tang, Yongqiang

2018-04-30

The controlled imputation method refers to a class of pattern mixture models that have been commonly used as sensitivity analyses of longitudinal clinical trials with nonignorable dropout in recent years. These pattern mixture models assume that participants in the experimental arm after dropout have similar response profiles to the control participants or have worse outcomes than otherwise similar participants who remain on the experimental treatment. In spite of its popularity, the controlled imputation has not been formally developed for longitudinal binary and ordinal outcomes partially due to the lack of a natural multivariate distribution for such endpoints. In this paper, we propose 2 approaches for implementing the controlled imputation for binary and ordinal data based respectively on the sequential logistic regression and the multivariate probit model. Efficient Markov chain Monte Carlo algorithms are developed for missing data imputation by using the monotone data augmentation technique for the sequential logistic regression and a parameter-expanded monotone data augmentation scheme for the multivariate probit model. We assess the performance of the proposed procedures by simulation and the analysis of a schizophrenia clinical trial and compare them with the fully conditional specification, last observation carried forward, and baseline observation carried forward imputation methods. Copyright © 2018 John Wiley & Sons, Ltd.

Developing an Array Binary Code Assessment Rubric for Multiple- Choice Questions Using Item Arrays and Binary-Coded Responses

ERIC Educational Resources Information Center

Haro, Elizabeth K.; Haro, Luis S.

2014-01-01

The multiple-choice question (MCQ) is the foundation of knowledge assessment in K-12, higher education, and standardized entrance exams (including the GRE, MCAT, and DAT). However, standard MCQ exams are limited with respect to the types of questions that can be asked when there are only five choices. MCQs offering additional choices more…

[One-night-stand behavior and associated factors among young men who have sex with men in Wuhan, China].

PubMed

Mao, Y X; Xiao, C C; Wang, T; Li, S Y; Yan, H

2017-06-10

Objective: This present study was to examine the prevalence and determinants of one-night-stand behavior among young men who have sex with men (YMSM). Methods: A total of 403 YMSM aged 16 to 25 were recruited through internet promotion, extending activity and HIV VCT in Wuhan. Data was gathered through anonymous questionnaire. Binary logistic regression was used to examine factors associated with one-night-stand behavior. Results: Of the 398 YMSM, 48.99 % (195/398) reported having had casual sex in the last 6 months. Of the ones having had casual sex, 34.29 % (60/175) and 28.65 % (49/171) reported using condoms consistently during anal or oral sexual contacts, respectively. These figures were lower than those of YMSM not having casual sexual contacts [with anal sex as 49.08 % (80/163) and oral sex as 38.85 % (61/157)]. 76.80 % (149/194) of the YMSM reported having had multiple sexual partners, with the figure higher than those without [33.15 % (60/181)] ( P <0.01). Results from the logistic regression analysis showed that the following factors seemed to be associated with casual sex activities among YMSM, including: often using internet, ( OR =4.89, 95 %CI : 1.90-12.54), taking illegal drugs ( OR =2.72, 95 %CI : 1.60-4.63). Conclusions: YMSM who had engaged in casual sex, practicing unprotected sex or having multiple sexual partners, were recognized as high risk population. Targeted intervention programs are needed to decrease the one-night-stand behavior. Internet intervention strategy seemed an important method to serve the purpose.

Predicting multi-level drug response with gene expression profile in multiple myeloma using hierarchical ordinal regression.

PubMed

Zhang, Xinyan; Li, Bingzong; Han, Huiying; Song, Sha; Xu, Hongxia; Hong, Yating; Yi, Nengjun; Zhuang, Wenzhuo

2018-05-10

Multiple myeloma (MM), like other cancers, is caused by the accumulation of genetic abnormalities. Heterogeneity exists in the patients' response to treatments, for example, bortezomib. This urges efforts to identify biomarkers from numerous molecular features and build predictive models for identifying patients that can benefit from a certain treatment scheme. However, previous studies treated the multi-level ordinal drug response as a binary response where only responsive and non-responsive groups are considered. It is desirable to directly analyze the multi-level drug response, rather than combining the response to two groups. In this study, we present a novel method to identify significantly associated biomarkers and then develop ordinal genomic classifier using the hierarchical ordinal logistic model. The proposed hierarchical ordinal logistic model employs the heavy-tailed Cauchy prior on the coefficients and is fitted by an efficient quasi-Newton algorithm. We apply our hierarchical ordinal regression approach to analyze two publicly available datasets for MM with five-level drug response and numerous gene expression measures. Our results show that our method is able to identify genes associated with the multi-level drug response and to generate powerful predictive models for predicting the multi-level response. The proposed method allows us to jointly fit numerous correlated predictors and thus build efficient models for predicting the multi-level drug response. The predictive model for the multi-level drug response can be more informative than the previous approaches. Thus, the proposed approach provides a powerful tool for predicting multi-level drug response and has important impact on cancer studies.

Epidemiologic research using probabilistic outcome definitions.

PubMed

Cai, Bing; Hennessy, Sean; Lo Re, Vincent; Small, Dylan S

2015-01-01

Epidemiologic studies using electronic healthcare data often define the presence or absence of binary clinical outcomes by using algorithms with imperfect specificity, sensitivity, and positive predictive value. This results in misclassification and bias in study results. We describe and evaluate a new method called probabilistic outcome definition (POD) that uses logistic regression to estimate the probability of a clinical outcome using multiple potential algorithms and then uses multiple imputation to make valid inferences about the risk ratio or other epidemiologic parameters of interest. We conducted a simulation to evaluate the performance of the POD method with two variables that can predict the true outcome and compared the POD method with the conventional method. The simulation results showed that when the true risk ratio is equal to 1.0 (null), the conventional method based on a binary outcome provides unbiased estimates. However, when the risk ratio is not equal to 1.0, the traditional method, either using one predictive variable or both predictive variables to define the outcome, is biased when the positive predictive value is <100%, and the bias is very severe when the sensitivity or positive predictive value is poor (less than 0.75 in our simulation). In contrast, the POD method provides unbiased estimates of the risk ratio both when this measure of effect is equal to 1.0 and not equal to 1.0. Even when the sensitivity and positive predictive value are low, the POD method continues to provide unbiased estimates of the risk ratio. The POD method provides an improved way to define outcomes in database research. This method has a major advantage over the conventional method in that it provided unbiased estimates of risk ratios and it is easy to use. Copyright © 2014 John Wiley & Sons, Ltd.

The Primordial Binary Fraction in Trumpler 14: Frequency and Multiplicity Parameters

NASA Astrophysics Data System (ADS)

Sabbi, Elena

2017-08-01

This is an astrometric proposal designed to identify and characterize the properties of medium- and long-period (orbital periods ranging from 1.8 to 100 years) visual binaries in the mass range between 4 and 20 Mo in the young compact cluster Trumpler 14 in the Carina Nebula. We aim to probe the virtually unexplored population of intermediate- and high-mass binaries that will experience a Roche-lobe overflow during their post-main-sequence evolution. These binaries are of particular interest because they are expected to be the progenitors of supernovae Type Ia, b, and c, X-ray binaries, double neutron stars and double black holes. Multiplicity properties of young stars can be further used to constrain the outcome of the star-formation process and hence distinguish between various formation scenarios. The medium- and long-period binaries (P> 0.5 yr) are hard to detect and expensive to characterize with traditional ground-based spectroscopy. Knowledge of their orbital properties is however crucial to properly estimate the overall fraction of OB stars whose evolution is affected by binary interaction and to predict the outcome of such interaction. Because of the well characterized PSF of WFC3/UVIS and its temporal stability, HST is the only facility able to characterize the properties of OB-type medium-period binaries in Tr14, and Tr14 is the only nearby high-density OB-type young cluster.

The Young Visual Binary Survey

NASA Astrophysics Data System (ADS)

Prato, Lisa; Avilez, Ian; Lindstrom, Kyle; Graham, Sean; Sullivan, Kendall; Biddle, Lauren; Skiff, Brian; Nofi, Larissa; Schaefer, Gail; Simon, Michal

2018-01-01

Differences in the stellar and circumstellar properties of the components of young binaries provide key information about star and disk formation and evolution processes. Because objects with separations of a few to a few hundred astronomical units share a common environment and composition, multiple systems allow us to control for some of the factors which play into star formation. We are completing analysis of a rich sample of about 100 pre-main sequence binaries and higher order multiples, primarily located in the Taurus and Ophiuchus star forming regions. This poster will highlight some of out recent, exciting results. All reduced spectra and the results of our analysis will be publicly available to the community at http://jumar.lowell.edu/BinaryStars/. Support for this research was provided in part by NSF award AST-1313399 and by NASA Keck KPDA funding.

The intermediate endpoint effect in logistic and probit regression

PubMed Central

MacKinnon, DP; Lockwood, CM; Brown, CH; Wang, W; Hoffman, JM

2010-01-01

Background An intermediate endpoint is hypothesized to be in the middle of the causal sequence relating an independent variable to a dependent variable. The intermediate variable is also called a surrogate or mediating variable and the corresponding effect is called the mediated, surrogate endpoint, or intermediate endpoint effect. Clinical studies are often designed to change an intermediate or surrogate endpoint and through this intermediate change influence the ultimate endpoint. In many intermediate endpoint clinical studies the dependent variable is binary, and logistic or probit regression is used. Purpose The purpose of this study is to describe a limitation of a widely used approach to assessing intermediate endpoint effects and to propose an alternative method, based on products of coefficients, that yields more accurate results. Methods The intermediate endpoint model for a binary outcome is described for a true binary outcome and for a dichotomization of a latent continuous outcome. Plots of true values and a simulation study are used to evaluate the different methods. Results Distorted estimates of the intermediate endpoint effect and incorrect conclusions can result from the application of widely used methods to assess the intermediate endpoint effect. The same problem occurs for the proportion of an effect explained by an intermediate endpoint, which has been suggested as a useful measure for identifying intermediate endpoints. A solution to this problem is given based on the relationship between latent variable modeling and logistic or probit regression. Limitations More complicated intermediate variable models are not addressed in the study, although the methods described in the article can be extended to these more complicated models. Conclusions Researchers are encouraged to use an intermediate endpoint method based on the product of regression coefficients. A common method based on difference in coefficient methods can lead to distorted conclusions regarding the intermediate effect. PMID:17942466

Experimental Determination of Impurity and Interdiffusion Coefficients in Seven Ti and Zr Binary Systems Using Diffusion Multiples

NASA Astrophysics Data System (ADS)

Chen, Zhangqi; Liu, Zi-Kui; Zhao, Ji-Cheng

2018-05-01

Diffusion coefficients of seven binary systems (Ti-Mo, Ti-Nb, Ti-Ta, Ti-Zr, Zr-Mo, Zr-Nb, and Zr-Ta) at 1200 °C, 1000 °C, and 800 °C were experimentally determined using three Ti-Mo-Nb-Ta-Zr diffusion multiples. Electron probe microanalysis (EPMA) was performed to collect concentration profiles at the binary diffusion regions. Forward simulation analysis (FSA) was then applied to extract both impurity and interdiffusion coefficients in Ti-rich and Zr-rich part of the bcc phase. Excellent agreements between our results and most of the literature data validate the high-throughput approach combining FSA with diffusion multiples to obtain a large amount of systematic diffusion data, which will help establish the diffusion (mobility) databases for the design and development of biomedical and structural Ti alloys.

Experimental Determination of Impurity and Interdiffusion Coefficients in Seven Ti and Zr Binary Systems Using Diffusion Multiples

NASA Astrophysics Data System (ADS)

Chen, Zhangqi; Liu, Zi-Kui; Zhao, Ji-Cheng

2018-07-01

Diffusion coefficients of seven binary systems (Ti-Mo, Ti-Nb, Ti-Ta, Ti-Zr, Zr-Mo, Zr-Nb, and Zr-Ta) at 1200 °C, 1000 °C, and 800 °C were experimentally determined using three Ti-Mo-Nb-Ta-Zr diffusion multiples. Electron probe microanalysis (EPMA) was performed to collect concentration profiles at the binary diffusion regions. Forward simulation analysis (FSA) was then applied to extract both impurity and interdiffusion coefficients in Ti-rich and Zr-rich part of the bcc phase. Excellent agreements between our results and most of the literature data validate the high-throughput approach combining FSA with diffusion multiples to obtain a large amount of systematic diffusion data, which will help establish the diffusion (mobility) databases for the design and development of biomedical and structural Ti alloys.

Upper bounds on the error probabilities and asymptotic error exponents in quantum multiple state discrimination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Audenaert, Koenraad M. R., E-mail: koenraad.audenaert@rhul.ac.uk; Department of Physics and Astronomy, University of Ghent, S9, Krijgslaan 281, B-9000 Ghent; Mosonyi, Milán, E-mail: milan.mosonyi@gmail.com

2014-10-01

We consider the multiple hypothesis testing problem for symmetric quantum state discrimination between r given states σ₁, …, σ{sub r}. By splitting up the overall test into multiple binary tests in various ways we obtain a number of upper bounds on the optimal error probability in terms of the binary error probabilities. These upper bounds allow us to deduce various bounds on the asymptotic error rate, for which it has been hypothesized that it is given by the multi-hypothesis quantum Chernoff bound (or Chernoff divergence) C(σ₁, …, σ{sub r}), as recently introduced by Nussbaum and Szkoła in analogy with Salikhov'smore » classical multi-hypothesis Chernoff bound. This quantity is defined as the minimum of the pairwise binary Chernoff divergences min{sub j« less

Prediction of cold and heat patterns using anthropometric measures based on machine learning.

PubMed

Lee, Bum Ju; Lee, Jae Chul; Nam, Jiho; Kim, Jong Yeol

2018-01-01

To examine the association of body shape with cold and heat patterns, to determine which anthropometric measure is the best indicator for discriminating between the two patterns, and to investigate whether using a combination of measures can improve the predictive power to diagnose these patterns. Based on a total of 4,859 subjects (3,000 women and 1,859 men), statistical analyses using binary logistic regression were performed to assess the significance of the difference and the predictive power of each anthropometric measure, and binary logistic regression and Naive Bayes with the variable selection technique were used to assess the improvement in the predictive power of the patterns using the combined measures. In women, the strongest indicators for determining the cold and heat patterns among anthropometric measures were body mass index (BMI) and rib circumference; in men, the best indicator was BMI. In experiments using a combination of measures, the values of the area under the receiver operating characteristic curve in women were 0.776 by Naive Bayes and 0.772 by logistic regression, and the values in men were 0.788 by Naive Bayes and 0.779 by logistic regression. Individuals with a higher BMI have a tendency toward a heat pattern in both women and men. The use of a combination of anthropometric measures can slightly improve the diagnostic accuracy. Our findings can provide fundamental information for the diagnosis of cold and heat patterns based on body shape for personalized medicine.

Are math readiness and personality predictive of first-year retention in engineering?

PubMed

Moses, Laurie; Hall, Cathy; Wuensch, Karl; De Urquidi, Karen; Kauffmann, Paul; Swart, William; Duncan, Steve; Dixon, Gene

2011-01-01

On the basis of J. G. Borkowski, L. K. Chan, and N. Muthukrishna's model of academic success (2000), the present authors hypothesized that freshman retention in an engineering program would be related to not only basic aptitude but also affective factors. Participants were 129 college freshmen with engineering as their stated major. Aptitude was measured by SAT verbal and math scores, high school grade-point average (GPA), and an assessment of calculus readiness. Affective factors were assessed by the NEO-Five Factor Inventory (FFI; P. I. Costa & R. R. McCrae, 2007), and the Nowicki-Duke Locus of Control (LOC) scale (S. Nowicki & M. Duke, 1974). A binary logistic regression analysis found that calculus readiness and high school GPA were predictive of retention. Scores on the Neuroticism and Openness subscales from the NEO-FFI and LOC were correlated with retention status, but Openness was the only affective factor with a significant unique effect in the binary logistic regression. Results of the study lend modest support to Borkowski's model.

[Willingness of Patients with Obesity to Use New Media in Rehabilitation Aftercare].

PubMed

Dorow, M; Löbner, M; Stein, J; Kind, P; Markert, J; Keller, J; Weidauer, E; Riedel-Heller, S G

2017-06-01

Digital media offer new possibilities in rehabilitation aftercare. This study investigates the rehabilitants' willingness to use new media (sms, internet, social networks) in rehabilitation aftercare and factors that are associated with the willingness to use media-based aftercare. 92 rehabilitants (patients with obesity) filled in a questionnaire on the willingness to use new media in rehabilitation aftercare. In order to identify influencing factors, binary logistic regression models were calculated. 3 quarters of the rehabilitants (76.1%) reported that they would be willing to use new media in rehabilitation aftercare. The binary logistic regression model yielded two factors that were associated with the willingness to use media-based aftercare: the possession of a smartphone and the willingness to receive telephone counseling for aftercare. The majority of the rehabilitants was willing to use new media in rehabilitation aftercare. The reasons for refusal of media-based aftercare need to be examined more closely. © Georg Thieme Verlag KG Stuttgart · New York.

Age at onset of major depressive disorder in Han Chinese women: Relationship with clinical features and family history☆

PubMed Central

Yang, Fuzhong; Li, Yihan; Xie, Dong; Shao, Chunhong; Ren, Jianer; Wu, Wenyuan; Zhang, Ning; Zhang, Zhen; Zou, Ying; Zhang, Jiulong; Qiao, Dongdong; Gao, Chengge; Li, Youhui; Hu, Jian; Deng, Hong; Wang, Gang; Du, Bo; Wang, Xumei; Liu, Tiebang; Gan, Zhaoyu; Peng, Juyi; Wei, Bo; Pan, Jiyang; Chen, Honghui; Sun, Shufan; Jia, Hong; Liu, Ying; Chen, Qiaoling; Wang, Xueyi; Cao, Juling; Lv, Luxian; Chen, Yunchun; Ha, Baowei; Ning, Yuping; Chen, YiPing; Kendler, Kenneth S.; Flint, Jonathan; Shi, Shenxun

2011-01-01

Background Individuals with early-onset depression may be a clinically distinct group with particular symptom patterns, illness course, comorbidity and family history. This question has not been previously investigated in a Han Chinese population. Methods We examined the clinical features of 1970 Han Chinese women with DSM-IV major depressive disorder (MDD) between 30 and 60 years of age across China. Analysis of linear, logistic and multiple logistic regression models was used to determine the association between age at onset (AAO) with continuous, binary and discrete characteristic clinical features of MDD. Results Earlier AAO was associated with more suicidal ideation and attempts and higher neuroticism, but fewer sleep, appetite and weight changes. Patients with an earlier AAO were more likely to suffer a chronic course (longer illness duration, more MDD episodes and longer index episode), increased rates of MDD in their parents and a lower likelihood of marriage. They tend to have higher comorbidity with anxiety disorders (general anxiety disorder, social phobia and agoraphobia) and dysthymia. Conclusions Early AAO in MDD may be an index of a more severe, highly comorbid and familial disorder. Our findings indicate that the features of MDD in China are similar to those reported elsewhere in the world. PMID:21782247

The CD4/CD8 ratio is associated with coronary artery disease (CAD) in elderly Chinese patients.

PubMed

Gao, Pan; Rong, Hong-Hui; Lu, Ting; Tang, Gang; Si, Liang-Yi; Lederer, James A; Xiong, Wei

2017-01-01

The aim of this study was to investigate the relationship between number of circulating T cells and coronary artery disease (CAD) in an elderly Chinese population. A total of 295 elderly inpatients (age≥60) were included in this cross-sectional study. Their clinical and biochemical characteristics were recorded. Patients were divided to two groups: control patients and CAD patients. The risk factors of CAD were explored by binary logistic regression analysis. Compared with control patients, the ratio of CD4 to CD8 T cells was significantly increased in CAD patients. There was no difference in the number of CD3, CD4, and CD8 T cells between the two groups. Multiple logistic regression analysis showed that CAD was independently associated with age, gender, body mass index (BMI), systolic blood pressure (SBP), chronic heart failure (CHF) and the CD4/CD8 ratio. In addition, after adjusting for different clinical parameters (including gender, age, CHF, hypertension, arrhythmia, SBP, and BMI), the risk of CAD was significantly increased in patients with a CD4/CD8 ratio>1.5. There was a strong and independent association between the ratio of CD4/CD8 and CAD in elderly Chinese population. Copyright © 2016. Published by Elsevier B.V.

Age at onset of major depressive disorder in Han Chinese women: relationship with clinical features and family history.

PubMed

Yang, Fuzhong; Li, Yihan; Xie, Dong; Shao, Chunhong; Ren, Jianer; Wu, Wenyuan; Zhang, Ning; Zhang, Zhen; Zou, Ying; Zhang, Jiulong; Qiao, Dongdong; Gao, Chengge; Li, Youhui; Hu, Jian; Deng, Hong; Wang, Gang; Du, Bo; Wang, Xumei; Liu, Tiebang; Gan, Zhaoyu; Peng, Juyi; Wei, Bo; Pan, Jiyang; Chen, Honghui; Sun, Shufan; Jia, Hong; Liu, Ying; Chen, Qiaoling; Wang, Xueyi; Cao, Juling; Lv, Luxian; Chen, Yunchun; Ha, Baowei; Ning, Yuping; Chen, Yiping; Kendler, Kenneth S; Flint, Jonathan; Shi, Shenxun

2011-12-01

Individuals with early-onset depression may be a clinically distinct group with particular symptom patterns, illness course, comorbidity and family history. This question has not been previously investigated in a Han Chinese population. We examined the clinical features of 1970 Han Chinese women with DSM-IV major depressive disorder (MDD) between 30 and 60 years of age across China. Analysis of linear, logistic and multiple logistic regression models was used to determine the association between age at onset (AAO) with continuous, binary and discrete characteristic clinical features of MDD. Earlier AAO was associated with more suicidal ideation and attempts and higher neuroticism, but fewer sleep, appetite and weight changes. Patients with an earlier AAO were more likely to suffer a chronic course (longer illness duration, more MDD episodes and longer index episode), increased rates of MDD in their parents and a lower likelihood of marriage. They tend to have higher comorbidity with anxiety disorders (general anxiety disorder, social phobia and agoraphobia) and dysthymia. Early AAO in MDD may be an index of a more severe, highly comorbid and familial disorder. Our findings indicate that the features of MDD in China are similar to those reported elsewhere in the world. Copyright © 2011 Elsevier B.V. All rights reserved.

Inferences about binary stellar populations using gravitational wave observations

NASA Astrophysics Data System (ADS)

Wysocki, Daniel; Gerosa, Davide; O'Shaughnessy, Richard; Belczynski, Krzysztof; Gladysz, Wojciech; Berti, Emanuele; Kesden, Michael; Holz, Daniel

2018-01-01

With the dawn of gravitational wave astronomy, enabled by the LIGO and Virgo interferometers, we now have a new window into the Universe. In the short time these detectors have been in use, multiple confirmed detections of gravitational waves from compact binary coalescences have been made. Stellar binary systems are one of the likely progenitors of the observed compact binary sources. If this is indeed the case, then we can use measured properties of these binary systems to learn about their progenitors. We will discuss the Bayesian framework in which we make these inferences, and results which include mass and spin distributions.

The massive multiple system HD 64315

NASA Astrophysics Data System (ADS)

Lorenzo, J.; Simón-Díaz, S.; Negueruela, I.; Vilardell, F.; Garcia, M.; Evans, C. J.; Montes, D.

2017-10-01

Context. The O6 Vn star HD 64315 is believed to belong to the star-forming region known as NGC 2467, but previous distance estimates do not support this association. Moreover, it has been identified as a spectroscopic binary, but existing data support contradictory values for its orbital period. Aims: We explore the multiple nature of this star with the aim of determining its distance, and understanding its connection to NGC 2467. Methods: A total of 52 high-resolution spectra have been gathered over a decade. We use their analysis, in combination with the photometric data from All Sky Automated Survey and Hipparcos catalogues, to conclude that HD 64315 is composed of at least two spectroscopic binaries, one of which is an eclipsing binary. We have developed our own program to fit four components to the combined line shapes. Once the four radial velocities were derived, we obtained a model to fit the radial-velocity curves using the Spectroscopic Binary Orbit Program (SBOP). We then implemented the radial velocities of the eclipsing binary and the light curves in the Wilson-Devinney code iteratively to derive stellar parameters for its components. We were also able to analyse the non-eclipsing binary, and to derive minimum masses for its components which dominate the system flux. Results: HD 64315 contains two binary systems, one of which is an eclipsing binary. The two binaries are separated by 0.09 arcsec (or 500 AU) if the most likely distance to the system, 5 kpc, is considered. The presence of fainter companions is not excluded by current observations. The non-eclipsing binary (HD 64315 AaAb) has a period of 2.70962901 ± 0.00000021 d. Its components are hotter than those of the eclipsing binary, and dominate the appearance of the system. The eclipsing binary (HD 64315 BaBb) has a shorter period of 1.0189569 ± 0.0000008 d. We derive masses of 14.6 ± 2.3 M⊙ for both components of the BaBb system. They are almost identical; both stars are overfilling their respective Roche lobes, and share a common envelope in an overcontact configuration. The non-eclipsing binary is a detached system composed of two stars with spectral types around O6 V with minimum masses of 10.8 M⊙ and 10.2 M⊙, and likely masses ≈ 30 M⊙. Conclusions: HD 64315 provides a cautionary tale about high-mass star isolation and multiplicity. Its total mass is likely above 90M⊙, but it seems to have formed without an accompanying cluster. It contains one the most massive overcontact binaries known, a likely merger progenitor in a very wide multiple system. Based on observations obtained at the European Southern Observatory under programmes 078.D-0665(A), 082-D.0136 and 093.A-9001(A). Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

Clinical features and risk factor analysis for lower extremity deep venous thrombosis in Chinese neurosurgical patients

PubMed Central

Guo, Fuyou; Shashikiran, Tagilapalli; Chen, Xi; Yang, Lei; Liu, Xianzhi; Song, Laijun

2015-01-01

Background: Deep venous thrombosis (DVT) contributes significantly to the morbidity and mortality of neurosurgical patients; however, no data regarding lower extremity DVT in postoperative Chinese neurosurgical patients have been reported. Materials and Methods: From January 2012 to December 2013, 196 patients without preoperative DVT who underwent neurosurgical operations were evaluated by color Doppler ultrasonography and D-dimer level measurements on the 3rd, 7th, and 14th days after surgery. Follow-up clinical data were recorded to determine the incidence of lower extremity DVT in postoperative neurosurgical patients and to analyze related clinical features. First, a single factor analysis, Chi-square test, was used to select statistically significant factors. Then, a multivariate analysis, binary logistic regression analysis, was used to determine risk factors for lower extremity DVT in postoperative neurosurgical patients. Results: Lower extremity DVT occurred in 61 patients, and the incidence of DVT was 31.1% in the enrolled Chinese neurosurgical patients. The common symptoms of DVT were limb swelling and lower extremity pain as well as increased soft tissue tension. The common sites of venous involvement were the calf muscle and peroneal and posterior tibial veins. The single factor analysis showed statistically significant differences in DVT risk factors, including age, hypertension, smoking status, operation time, a bedridden or paralyzed state, the presence of a tumor, postoperative dehydration, and glucocorticoid treatment, between the two groups (P < 0.05). The binary logistic regression analysis showed that an age greater than 50 years, hypertension, a bedridden or paralyzed state, the presence of a tumor, and postoperative dehydration were risk factors for lower extremity DVT in postoperative neurosurgical patients. Conclusions: Lower extremity DVT was a common complication following craniotomy in the enrolled Chinese neurosurgical patients. Multiple factors were identified as predictive of DVT in neurosurgical patients, including the presence of a tumor, an age greater than 50 years, hypertension, and immobility. PMID:26752303

The logistic model for predicting the non-gonoactive Aedes aegypti females.

PubMed

Reyes-Villanueva, Filiberto; Rodríguez-Pérez, Mario A

2004-01-01

To estimate, using logistic regression, the likelihood of occurrence of a non-gonoactive Aedes aegypti female, previously fed human blood, with relation to body size and collection method. This study was conducted in Monterrey, Mexico, between 1994 and 1996. Ten samplings of 60 mosquitoes of Ae. aegypti females were carried out in three dengue endemic areas: six of biting females, two of emerging mosquitoes, and two of indoor resting females. Gravid females, as well as those with blood in the gut were removed. Mosquitoes were taken to the laboratory and engorged on human blood. After 48 hours, ovaries were dissected to register whether they were gonoactive or non-gonoactive. Wing-length in mm was an indicator for body size. The logistic regression model was used to assess the likelihood of non-gonoactivity, as a binary variable, in relation to wing-length and collection method. Of the 600 females, 164 (27%) remained non-gonoactive, with a wing-length range of 1.9-3.2 mm, almost equal to that of all females (1.8-3.3 mm). The logistic regression model showed a significant likelihood of a female remaining non-gonoactive (Y=1). The collection method did not influence the binary response, but there was an inverse relationship between non-gonoactivity and wing-length. Dengue vector populations from Monterrey, Mexico display a wide-range body size. Logistic regression was a useful tool to estimate the likelihood for an engorged female to remain non-gonoactive. The necessity for a second blood meal is present in any female, but small mosquitoes are more likely to bite again within a 2-day interval, in order to attain egg maturation. The English version of this paper is available too at: http://www.insp.mx/salud/index.html.

Logistic Regression and Path Analysis Method to Analyze Factors influencing Students’ Achievement

NASA Astrophysics Data System (ADS)

Noeryanti, N.; Suryowati, K.; Setyawan, Y.; Aulia, R. R.

2018-04-01

Students' academic achievement cannot be separated from the influence of two factors namely internal and external factors. The first factors of the student (internal factors) consist of intelligence (X1), health (X2), interest (X3), and motivation of students (X4). The external factors consist of family environment (X5), school environment (X6), and society environment (X7). The objects of this research are eighth grade students of the school year 2016/2017 at SMPN 1 Jiwan Madiun sampled by using simple random sampling. Primary data are obtained by distributing questionnaires. The method used in this study is binary logistic regression analysis that aims to identify internal and external factors that affect student’s achievement and how the trends of them. Path Analysis was used to determine the factors that influence directly, indirectly or totally on student’s achievement. Based on the results of binary logistic regression, variables that affect student’s achievement are interest and motivation. And based on the results obtained by path analysis, factors that have a direct impact on student’s achievement are students’ interest (59%) and students’ motivation (27%). While the factors that have indirect influences on students’ achievement, are family environment (97%) and school environment (37).

An Attempt at Quantifying Factors that Affect Efficiency in the Management of Solid Waste Produced by Commercial Businesses in the City of Tshwane, South Africa

PubMed Central

Worku, Yohannes; Muchie, Mammo

2012-01-01

Objective. The objective was to investigate factors that affect the efficient management of solid waste produced by commercial businesses operating in the city of Pretoria, South Africa. Methods. Data was gathered from 1,034 businesses. Efficiency in solid waste management was assessed by using a structural time-based model designed for evaluating efficiency as a function of the length of time required to manage waste. Data analysis was performed using statistical procedures such as frequency tables, Pearson's chi-square tests of association, and binary logistic regression analysis. Odds ratios estimated from logistic regression analysis were used for identifying key factors that affect efficiency in the proper disposal of waste. Results. The study showed that 857 of the 1,034 businesses selected for the study (83%) were found to be efficient enough with regards to the proper collection and disposal of solid waste. Based on odds ratios estimated from binary logistic regression analysis, efficiency in the proper management of solid waste was significantly influenced by 4 predictor variables. These 4 influential predictor variables are lack of adherence to waste management regulations, wrong perception, failure to provide customers with enough trash cans, and operation of businesses by employed managers, in a decreasing order of importance. PMID:23209483

The Mantel-Haenszel procedure revisited: models and generalizations.

PubMed

Fidler, Vaclav; Nagelkerke, Nico

2013-01-01

Several statistical methods have been developed for adjusting the Odds Ratio of the relation between two dichotomous variables X and Y for some confounders Z. With the exception of the Mantel-Haenszel method, commonly used methods, notably binary logistic regression, are not symmetrical in X and Y. The classical Mantel-Haenszel method however only works for confounders with a limited number of discrete strata, which limits its utility, and appears to have no basis in statistical models. Here we revisit the Mantel-Haenszel method and propose an extension to continuous and vector valued Z. The idea is to replace the observed cell entries in strata of the Mantel-Haenszel procedure by subject specific classification probabilities for the four possible values of (X,Y) predicted by a suitable statistical model. For situations where X and Y can be treated symmetrically we propose and explore the multinomial logistic model. Under the homogeneity hypothesis, which states that the odds ratio does not depend on Z, the logarithm of the odds ratio estimator can be expressed as a simple linear combination of three parameters of this model. Methods for testing the homogeneity hypothesis are proposed. The relationship between this method and binary logistic regression is explored. A numerical example using survey data is presented.

The Mantel-Haenszel Procedure Revisited: Models and Generalizations

PubMed Central

Fidler, Vaclav; Nagelkerke, Nico

2013-01-01

Several statistical methods have been developed for adjusting the Odds Ratio of the relation between two dichotomous variables X and Y for some confounders Z. With the exception of the Mantel-Haenszel method, commonly used methods, notably binary logistic regression, are not symmetrical in X and Y. The classical Mantel-Haenszel method however only works for confounders with a limited number of discrete strata, which limits its utility, and appears to have no basis in statistical models. Here we revisit the Mantel-Haenszel method and propose an extension to continuous and vector valued Z. The idea is to replace the observed cell entries in strata of the Mantel-Haenszel procedure by subject specific classification probabilities for the four possible values of (X,Y) predicted by a suitable statistical model. For situations where X and Y can be treated symmetrically we propose and explore the multinomial logistic model. Under the homogeneity hypothesis, which states that the odds ratio does not depend on Z, the logarithm of the odds ratio estimator can be expressed as a simple linear combination of three parameters of this model. Methods for testing the homogeneity hypothesis are proposed. The relationship between this method and binary logistic regression is explored. A numerical example using survey data is presented. PMID:23516463

ON MODEL SELECTION STRATEGIES TO IDENTIFY GENES UNDERLYING BINARY TRAITS USING GENOME-WIDE ASSOCIATION DATA.

PubMed

Wu, Zheyang; Zhao, Hongyu

2012-01-01

For more fruitful discoveries of genetic variants associated with diseases in genome-wide association studies, it is important to know whether joint analysis of multiple markers is more powerful than the commonly used single-marker analysis, especially in the presence of gene-gene interactions. This article provides a statistical framework to rigorously address this question through analytical power calculations for common model search strategies to detect binary trait loci: marginal search, exhaustive search, forward search, and two-stage screening search. Our approach incorporates linkage disequilibrium, random genotypes, and correlations among score test statistics of logistic regressions. We derive analytical results under two power definitions: the power of finding all the associated markers and the power of finding at least one associated marker. We also consider two types of error controls: the discovery number control and the Bonferroni type I error rate control. After demonstrating the accuracy of our analytical results by simulations, we apply them to consider a broad genetic model space to investigate the relative performances of different model search strategies. Our analytical study provides rapid computation as well as insights into the statistical mechanism of capturing genetic signals under different genetic models including gene-gene interactions. Even though we focus on genetic association analysis, our results on the power of model selection procedures are clearly very general and applicable to other studies.

ON MODEL SELECTION STRATEGIES TO IDENTIFY GENES UNDERLYING BINARY TRAITS USING GENOME-WIDE ASSOCIATION DATA

PubMed Central

Wu, Zheyang; Zhao, Hongyu

2013-01-01

For more fruitful discoveries of genetic variants associated with diseases in genome-wide association studies, it is important to know whether joint analysis of multiple markers is more powerful than the commonly used single-marker analysis, especially in the presence of gene-gene interactions. This article provides a statistical framework to rigorously address this question through analytical power calculations for common model search strategies to detect binary trait loci: marginal search, exhaustive search, forward search, and two-stage screening search. Our approach incorporates linkage disequilibrium, random genotypes, and correlations among score test statistics of logistic regressions. We derive analytical results under two power definitions: the power of finding all the associated markers and the power of finding at least one associated marker. We also consider two types of error controls: the discovery number control and the Bonferroni type I error rate control. After demonstrating the accuracy of our analytical results by simulations, we apply them to consider a broad genetic model space to investigate the relative performances of different model search strategies. Our analytical study provides rapid computation as well as insights into the statistical mechanism of capturing genetic signals under different genetic models including gene-gene interactions. Even though we focus on genetic association analysis, our results on the power of model selection procedures are clearly very general and applicable to other studies. PMID:23956610

Inferring Binary and Trinary Stellar Populations in Photometric and Astrometric Surveys

NASA Astrophysics Data System (ADS)

Widmark, Axel; Leistedt, Boris; Hogg, David W.

2018-04-01

Multiple stellar systems are ubiquitous in the Milky Way but are often unresolved and seen as single objects in spectroscopic, photometric, and astrometric surveys. However, modeling them is essential for developing a full understanding of large surveys such as Gaia and connecting them to stellar and Galactic models. In this paper, we address this problem by jointly fitting the Gaia and Two Micron All Sky Survey photometric and astrometric data using a data-driven Bayesian hierarchical model that includes populations of binary and trinary systems. This allows us to classify observations into singles, binaries, and trinaries, in a robust and efficient manner, without resorting to external models. We are able to identify multiple systems and, in some cases, make strong predictions for the properties of their unresolved stars. We will be able to compare such predictions with Gaia Data Release 4, which will contain astrometric identification and analysis of binary systems.

Multiplicity of the Galactic Senior Citizens: A high-resolution search for cool subdwarf companions

NASA Astrophysics Data System (ADS)

Ziegler, Carl; Law, Nicholas M.

2015-01-01

Cool subdwarfs, with spectral types late K and M, are the oldest members of the low-mass stellar population. Mostly present in the galactic halo, subdwarfs are characterized by their low metallicity and high proper-motions. Understanding their binary fraction could give key insights into the star formation process early in the Milky Way's history. However, because of their low luminosity and relative rarity in the solar neighborhood, binary surveys of cool subdwarfs have suffered from small sample sizes and large incompleteness gaps. It appears, however, that the binary fraction of red subdwarfs is much lower than for their main-sequence cousins. Using the highly efficient Robo-AO system, we present the largest high-resolution survey of subdwarfs yet. We find from 349 target cool subdwarfs, 39 are in multiple systems, 13 newly discovered, for a binary fraction of 11 ± 1.8%.

Local Multi-Grouped Binary Descriptor With Ring-Based Pooling Configuration and Optimization.

PubMed

Gao, Yongqiang; Huang, Weilin; Qiao, Yu

2015-12-01

Local binary descriptors are attracting increasingly attention due to their great advantages in computational speed, which are able to achieve real-time performance in numerous image/vision applications. Various methods have been proposed to learn data-dependent binary descriptors. However, most existing binary descriptors aim overly at computational simplicity at the expense of significant information loss which causes ambiguity in similarity measure using Hamming distance. In this paper, by considering multiple features might share complementary information, we present a novel local binary descriptor, referred as ring-based multi-grouped descriptor (RMGD), to successfully bridge the performance gap between current binary and floated-point descriptors. Our contributions are twofold. First, we introduce a new pooling configuration based on spatial ring-region sampling, allowing for involving binary tests on the full set of pairwise regions with different shapes, scales, and distances. This leads to a more meaningful description than the existing methods which normally apply a limited set of pooling configurations. Then, an extended Adaboost is proposed for an efficient bit selection by emphasizing high variance and low correlation, achieving a highly compact representation. Second, the RMGD is computed from multiple image properties where binary strings are extracted. We cast multi-grouped features integration as rankSVM or sparse support vector machine learning problem, so that different features can compensate strongly for each other, which is the key to discriminativeness and robustness. The performance of the RMGD was evaluated on a number of publicly available benchmarks, where the RMGD outperforms the state-of-the-art binary descriptors significantly.

Stationary Size Distributions of Growing Cells with Binary and Multiple Cell Division

NASA Astrophysics Data System (ADS)

Rading, M. M.; Engel, T. A.; Lipowsky, R.; Valleriani, A.

2011-10-01

Populations of unicellular organisms that grow under constant environmental conditions are considered theoretically. The size distribution of these cells is calculated analytically, both for the usual process of binary division, in which one mother cell produces always two daughter cells, and for the more complex process of multiple division, in which one mother cell can produce 2 n daughter cells with n=1,2,3,… . The latter mode of division is inspired by the unicellular algae Chlamydomonas reinhardtii. The uniform response of the whole population to different environmental conditions is encoded in the individual rates of growth and division of the cells. The analytical treatment of the problem is based on size-dependent rules for cell growth and stochastic transition processes for cell division. The comparison between binary and multiple division shows that these different division processes lead to qualitatively different results for the size distribution and the population growth rates.

Depression and anxiety in multiple system atrophy.

PubMed

Zhang, L-Y; Cao, B; Zou, Y-T; Wei, Q-Q; Ou, R-W; Zhao, B; Wu, Y; Shang, H-F

2018-01-01

It has been noticed that the patients with multiple system atrophy (MSA) can accompany with depression and anxiety. This study aimed to establish the incidence and determinants of depression and anxiety symptoms in Chinese MSA patients. A total of 237 MSA patients were enrolled in the study. Neuropsychological assessment was performed using Hamilton Depression Rating Scale-24 items and Hamilton Anxiety Rating Scale. We found that 62.0% and 71.7% patients had at least mild depression and anxiety symptoms, respectively. The severity of depression of MSA patients was associated with lower educational years (P=.024), longer disease duration (P<.001), and disease severity (P<.001). The severity of anxiety was associated with increased disease duration (P<.001), disease severity (P=.013), and orthostatic hypotension (P=.005). Binary logistic regression showed the determinants of depression and anxiety were female gender, longer disease duration, and disease severity. Depression and anxiety symptoms are common in patients with MSA. Neurologists should pay attention to depression and anxiety in patients with MSA, especially in female patients and those with longer disease duration and severe disease condition. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Glucagon gene polymorphism modifies the effects of smoking and physical activity on risk of type 2 diabetes mellitus in Han Chinese.

PubMed

Li, Linlin; Gao, Kaiping; Zhao, Jingzhi; Feng, Tianping; Yin, Lei; Wang, Jinjin; Wang, Chongjian; Li, Chunyang; Wang, Yan; Wang, Qian; Zhai, Yujia; You, Haifei; Ren, Yongcheng; Wang, Bingyuan; Hu, Dongsheng

2014-01-25

Few genome-wide association studies have considered interactions between multiple genetic variants and environmental factors associated with disease. The interaction was examined between a glucagon gene (GCG) polymorphism and smoking, alcohol consumption and physical activity and the association with risk of type 2 diabetes mellitus (T2DM) in a case-control study of Chinese Han subjects. The rs12104705 polymorphism of GCG and interactions with environmental variables were analyzed for 9619 participants by binary multiple logistic regression. Smoking with the C-C haplotype of rs12104705 was associated with increased risk of T2DM (OR=1.174, 95% CI=1.013-1.361). Moderate and high physical activity with the C-C genotype was associated with decreased risk of T2DM as compared with low physical activity with the genotype (OR=0.251, 95% CI=0.206-0.306 and OR=0.190, 95% CI=0.164-0.220). However, the interaction of drinking and genotype was not associated with risk of T2DM. Genetic polymorphism in rs12104705 of GCG may interact with smoking and physical activity to modify the risk of T2DM. © 2013.

The multiplicity of massive stars: A high angular resolution survey with the HST fine guidance sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aldoretta, E. J.; Gies, D. R.; Henry, T. J.

2015-01-01

We present the results of an all-sky survey made with the Fine Guidance Sensor on the Hubble Space Telescope to search for angularly resolved binary systems among massive stars. The sample of 224 stars is comprised mainly of Galactic O- and B-type stars and luminous blue variables, plus a few luminous stars in the Large Magellanic Cloud. The FGS TRANS mode observations are sensitive to the detection of companions with an angular separation between 0.″01 and 1.″0 and brighter than △m=5. The FGS observations resolved 52 binary and 6 triple star systems and detected partially resolved binaries in 7 additionalmore » targets (43 of these are new detections). These numbers yield a companion detection frequency of 29% for the FGS survey. We also gathered literature results on the numbers of close spectroscopic binaries and wider astrometric binaries among the sample, and we present estimates of the frequency of multiple systems and the companion frequency for subsets of stars residing in clusters and associations, field stars, and runaway stars. These results confirm the high multiplicity fraction, especially among massive stars in clusters and associations. We show that the period distribution is approximately flat in increments of logP. We identify a number of systems of potential interest for long-term orbital determinations, and we note the importance of some of these companions for the interpretation of the radial velocities and light curves of close binaries that have third companions.« less

Sample size determination for logistic regression on a logit-normal distribution.

PubMed

Kim, Seongho; Heath, Elisabeth; Heilbrun, Lance

2017-06-01

Although the sample size for simple logistic regression can be readily determined using currently available methods, the sample size calculation for multiple logistic regression requires some additional information, such as the coefficient of determination ([Formula: see text]) of a covariate of interest with other covariates, which is often unavailable in practice. The response variable of logistic regression follows a logit-normal distribution which can be generated from a logistic transformation of a normal distribution. Using this property of logistic regression, we propose new methods of determining the sample size for simple and multiple logistic regressions using a normal transformation of outcome measures. Simulation studies and a motivating example show several advantages of the proposed methods over the existing methods: (i) no need for [Formula: see text] for multiple logistic regression, (ii) available interim or group-sequential designs, and (iii) much smaller required sample size.

Double stars with wide separations in the AGK3 - II. The wide binaries and the multiple systems*

NASA Astrophysics Data System (ADS)

Halbwachs, J.-L.; Mayor, M.; Udry, S.

2017-02-01

A large observation programme was carried out to measure the radial velocities of the components of a selection of common proper motion (CPM) stars to select the physical binaries. 80 wide binaries (WBs) were detected, and 39 optical pairs were identified. By adding CPM stars with separations close enough to be almost certain that they are physical, a bias-controlled sample of 116 WBs was obtained, and used to derive the distribution of separations from 100 to 30 000 au. The distribution obtained does not match the log-constant distribution, but agrees with the log-normal distribution. The spectroscopic binaries detected among the WB components were used to derive statistical information about the multiple systems. The close binaries in WBs seem to be like those detected in other field stars. As for the WBs, they seem to obey the log-normal distribution of periods. The number of quadruple systems agrees with the no correlation hypothesis; this indicates that an environment conducive to the formation of WBs does not favour the formation of subsystems with periods shorter than 10 yr.

On the frequency of close binary systems among very low-mass stars and brown dwarfs

NASA Astrophysics Data System (ADS)

Maxted, P. F. L.; Jeffries, R. D.

2005-09-01

We have used Monte Carlo simulation techniques and published radial velocity surveys to constrain the frequency of very low-mass star (VLMS) and brown dwarf (BD) binary systems and their separation (a) distribution. Gaussian models for the separation distribution with a peak at a= 4au and 0.6 <=σlog(a/au)<= 1.0, correctly predict the number of observed binaries, yielding a close (a < 2.6au) binary frequency of 17-30 per cent and an overall VLMS/BD binary frequency of 32-45 per cent. We find that the available N-body models of VLMS/BD formation from dynamically decaying protostellar multiple systems are excluded at >99 per cent confidence because they predict too few close binary VLMS/BDs. The large number of close binaries and high overall binary frequency are also very inconsistent with recent smoothed particle hydrodynamical modelling and argue against a dynamical origin for VLMS/BDs.

Close binary systems among very low-mass stars and brown dwarfs

NASA Astrophysics Data System (ADS)

Jeffries, R. D.; Maxted, P. F. L.

2005-12-01

Using Monte Carlo simulations and published radial velocity surveys we have constrained the frequency and separation (a) distribution of very low-mass star (VLM) and brown dwarf (BD) binary systems. We find that simple Gaussian extensions of the observed wide binary distribution, with a peak at 4 AU and 0.6<\\sigma_{\\log(a/AU)}<1.0, correctly reproduce the observed number of close binary systems, implying a close (a<2.6 AU) binary frequency of 17-30 % and overall frequency of 32-45 %. N-body models of the dynamical decay of unstable protostellar multiple systems are excluded with high confidence because they do not produce enough close binary VLMs/BDs. The large number of close binaries and high overall binary frequency are also completely inconsistent with published smoothed particle hydrodynamical modelling and argue against a dynamical origin for VLMs/BDs.

Predictors of Employment Outcomes for State-Federal Vocational Rehabilitation Consumers with HIV/AIDS

ERIC Educational Resources Information Center

Jung, Youngoh; Schaller, James; Bellini, James

2010-01-01

In this study, the authors investigated the effects of demographic, medical, and vocational rehabilitation service variables on employment outcomes of persons living with HIV/AIDS. Binary logistic regression analyses were conducted to determine predictors of employment outcomes using two groups drawn from Rehabilitation Services Administration…

Who Benefits from Tuition Discounts at Public Universities?

ERIC Educational Resources Information Center

Hillman, Nicholas W.

2010-01-01

This article uses data from the 2004 National Postsecondary Student Aid Study to provide insight about the range of tuition discounting practices at public institutions. Specifically, it examines the characteristics of students who receive tuition discounts from public four-year colleges and universities. A binary logistic regression is applied to…

An Examination of Master's Student Retention & Completion

ERIC Educational Resources Information Center

Barry, Melissa; Mathies, Charles

2011-01-01

This study was conducted at a research-extensive public university in the southeastern United States. It examined the retention and completion of master's degree students across numerous disciplines. Results were derived from a series of descriptive statistics, T-tests, and a series of binary logistic regression models. The findings from binary…

Graduate Unemployment in South Africa: Social Inequality Reproduced

ERIC Educational Resources Information Center

Baldry, Kim

2016-01-01

In this study, I examine the influence of demographic and educational characteristics of South African graduates on their employment/unemployment status. A sample of 1175 respondents who graduated between 2006 and 2012 completed an online survey. Using binary logistic regression, the strongest determinants of unemployment were the graduates' race,…

Commitment of Licensed Social Workers to Aging Practice

ERIC Educational Resources Information Center

Simons, Kelsey; Bonifas, Robin; Gammonley, Denise

2011-01-01

This study sought to identify client, professional, and employment characteristics that enhance licensed social workers' commitment to aging practice. A series of binary logistic regressions were performed using data from 181 licensed, full-time social workers who reported aging as their primary specialty area as part of the 2004 NASW's national…

Control of broadband optically generated ultrasound pulses using binary amplitude holograms.

PubMed

Brown, Michael D; Jaros, Jiri; Cox, Ben T; Treeby, Bradley E

2016-04-01

In this work, the use of binary amplitude holography is investigated as a mechanism to focus broadband acoustic pulses generated by high peak-power pulsed lasers. Two algorithms are described for the calculation of the binary holograms; one using ray-tracing, and one using an optimization based on direct binary search. It is shown using numerical simulations that when a binary amplitude hologram is excited by a train of laser pulses at its design frequency, the acoustic field can be focused at a pre-determined distribution of points, including single and multiple focal points, and line and square foci. The numerical results are validated by acoustic field measurements from binary amplitude holograms, excited by a high peak-power laser.

Guidance for the utility of linear models in meta-analysis of genetic association studies of binary phenotypes.

PubMed

Cook, James P; Mahajan, Anubha; Morris, Andrew P

2017-02-01

Linear mixed models are increasingly used for the analysis of genome-wide association studies (GWAS) of binary phenotypes because they can efficiently and robustly account for population stratification and relatedness through inclusion of random effects for a genetic relationship matrix. However, the utility of linear (mixed) models in the context of meta-analysis of GWAS of binary phenotypes has not been previously explored. In this investigation, we present simulations to compare the performance of linear and logistic regression models under alternative weighting schemes in a fixed-effects meta-analysis framework, considering designs that incorporate variable case-control imbalance, confounding factors and population stratification. Our results demonstrate that linear models can be used for meta-analysis of GWAS of binary phenotypes, without loss of power, even in the presence of extreme case-control imbalance, provided that one of the following schemes is used: (i) effective sample size weighting of Z-scores or (ii) inverse-variance weighting of allelic effect sizes after conversion onto the log-odds scale. Our conclusions thus provide essential recommendations for the development of robust protocols for meta-analysis of binary phenotypes with linear models.

Adjustable repetition-rate multiplication of optical pulses using fractional temporal Talbot effect with preceded binary intensity modulation

NASA Astrophysics Data System (ADS)

Xie, Qijie; Zheng, Bofang; Shu, Chester

2017-05-01

We demonstrate a simple approach for adjustable multiplication of optical pulses in a fiber using the temporal Talbot effect. Binary electrical patterns are used to control the multiplication factor in our approach. The input 10 GHz picosecond pulses are pedestal-free and are shaped directly from a CW laser. The pulses are then intensity modulated by different sets of binary patterns prior to entering a fiber of fixed dispersion. Tunable repetition-rate multiplication by different factors of 2, 4, and 8 have been achieved and up to 80 GHz pulse train has been experimentally generated. We also evaluate numerically the influence of the extinction ratio of the intensity modulator on the performance of the multiplied pulse train. In addition, the impact of the modulator bias on the uniformity of the output pulses has also been analyzed through simulation and experiment and a good agreement is reached. Last, we perform numerical simulation on the RF spectral characteristics of the output pulses. The insensitivity of the signal-to-subharmonic noise ratio (SSNR) to the laser linewidth shows that our multiplication scheme is highly tolerant to the incoherence of the input optical pulses.

Probability Quantization for Multiplication-Free Binary Arithmetic Coding

NASA Technical Reports Server (NTRS)

Cheung, K. -M.

1995-01-01

A method has been developed to improve on Witten's binary arithmetic coding procedure of tracking a high value and a low value. The new method approximates the probability of the less probable symbol, which improves the worst-case coding efficiency.

Revealing Companions to Nearby Stars with Astrometric Acceleration

DTIC Science & Technology

2012-07-01

objects, such as stellar -mass black holes or failed supernova (Gould & Salim 2002). Table 4 includes a sample of some of the most interesting dis...knowledge of binary and multiple star statistics is needed for the study of star formation, for stellar population synthesis, for predicting the...frequency of supernovae, blue stragglers, X-ray binaries, etc. The statistical properties of binaries strongly depend on stellar mass. Only for nearby solar

A local equation for differential diagnosis of β-thalassemia trait and iron deficiency anemia by logistic regression analysis in Southeast Iran.

PubMed

Sargolzaie, Narjes; Miri-Moghaddam, Ebrahim

2014-01-01

The most common differential diagnosis of β-thalassemia (β-thal) trait is iron deficiency anemia. Several red blood cell equations were introduced during different studies for differential diagnosis between β-thal trait and iron deficiency anemia. Due to genetic variations in different regions, these equations cannot be useful in all population. The aim of this study was to determine a native equation with high accuracy for differential diagnosis of β-thal trait and iron deficiency anemia for the Sistan and Baluchestan population by logistic regression analysis. We selected 77 iron deficiency anemia and 100 β-thal trait cases. We used binary logistic regression analysis and determined best equations for probability prediction of β-thal trait against iron deficiency anemia in our population. We compared diagnostic values and receiver operative characteristic (ROC) curve related to this equation and another 10 published equations in discriminating β-thal trait and iron deficiency anemia. The binary logistic regression analysis determined the best equation for best probability prediction of β-thal trait against iron deficiency anemia with area under curve (AUC) 0.998. Based on ROC curves and AUC, Green & King, England & Frazer, and then Sirdah indices, respectively, had the most accuracy after our equation. We suggest that to get the best equation and cut-off in each region, one needs to evaluate specific information of each region, specifically in areas where populations are homogeneous, to provide a specific formula for differentiating between β-thal trait and iron deficiency anemia.

SLoWPoKES-II: 100,000 WIDE BINARIES IDENTIFIED IN SDSS WITHOUT PROPER MOTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhital, Saurav; West, Andrew A.; Schluns, Kyle J.

2015-08-15

We present the Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES)-II catalog of low-mass visual binaries identified from the Sloan Digital Sky Survey (SDSS) by matching photometric distances. The candidate pairs are vetted by comparing the stellar information. The candidate pairs are vetted by comparing the stellar density at their respective Galactic positions to Monte Carlo realizations of a simulated Milky Way. In this way, we are able to identify large numbers of bona fide wide binaries without the need for proper motions. Here, 105,537 visual binaries with angular separations of ∼1–20″ were identified, each with a probability ofmore » chance alignment of ≤5%. This is the largest catalog of bona fide wide binaries to date, and it contains a diversity of systems—in mass, mass ratios, binary separations, metallicity, and evolutionary states—that should facilitate follow-up studies to characterize the properties of M dwarfs and white dwarfs. There is a subtle but definitive suggestion of multiple populations in the physical separation distribution, supporting earlier findings. We suggest that wide binaries are composed of multiple populations, most likely representing different formation modes. There are 141 M7 or later wide binary candidates, representing a seven-fold increase over the number currently known. These binaries are too wide to have been formed via the ejection mechanism. Finally, we found that 6% of spectroscopically confirmed M dwarfs are not included in the SDSS STAR catalog; they are misclassified as extended sources due to the presence of a nearby or partially resolved companion. The SLoWPoKES-II catalog is publicly available to the entire community on the World Wide Web via the Filtergraph data visualization portal.« less

The Possibility of Multiple Habitable Worlds Orbiting Binary Stars

NASA Astrophysics Data System (ADS)

Mason, P. A.

2014-03-01

Are there planetary systems for which there is life on multiple worlds? Where are these fruitful planetary systems and how do we detect them? In order to address these questions; conditions which enable life and those that prevent or destroy it must be considered. Many constraints are specific to planetary systems, independent of the number of worlds in habitable zones. For instance, life on rocky planets or moons likely requires the right abundance of volatiles and radiogenic elements for prolonged geologic activity. Catastrophic sterilization events such as nearby supernovae and gamma-ray bursts affect entire planetary systems not just specific worlds. Giant planets may either enhance or disrupt the development of complex life within a given system. It might be rare for planetary systems to possess qualities that promote life and lucky enough to avoid cataclysm. However, multiple habitable planets may provide enhanced chances for advanced life to develop. The best predictor of life on one habitable zone planet might be the presence of life on its neighbor as panspermia may occur in planetary systems with several habitable worlds. Circumbinary habitability may go hand in hand with habitability of multiple worlds. The circumstances in which the Binary Habitability Mechanism (BHM) operates are reviewed. In some cases, the early synchronization of the primary's rotation with the binary period results in a reduction of XUV flux and stellar winds. Main sequence binaries with periods in the 10-50 days provide excellent habitable environments, within which multiple worlds may thrive. Planets and moons in these habitable zones need less magnetic protection than their single star counterparts. Exomoons orbiting a Neptune-like planet, within a BHM protected habitable zone, are expected to be habitable over a wide range of semimajor axes due to a larger planetary Hill radius. A result confirmed by numerical orbital calculations. Binaries containing a solar type star with a lower mass companion provide enhanced habitable zones as well as improved photosynthetic flux for habitable zone worlds.

Logistic Mixed Models to Investigate Implicit and Explicit Belief Tracking.

PubMed

Lages, Martin; Scheel, Anne

2016-01-01

We investigated the proposition of a two-systems Theory of Mind in adults' belief tracking. A sample of N = 45 participants predicted the choice of one of two opponent players after observing several rounds in an animated card game. Three matches of this card game were played and initial gaze direction on target and subsequent choice predictions were recorded for each belief task and participant. We conducted logistic regressions with mixed effects on the binary data and developed Bayesian logistic mixed models to infer implicit and explicit mentalizing in true belief and false belief tasks. Although logistic regressions with mixed effects predicted the data well a Bayesian logistic mixed model with latent task- and subject-specific parameters gave a better account of the data. As expected explicit choice predictions suggested a clear understanding of true and false beliefs (TB/FB). Surprisingly, however, model parameters for initial gaze direction also indicated belief tracking. We discuss why task-specific parameters for initial gaze directions are different from choice predictions yet reflect second-order perspective taking.

The association between insured male expatriates' knowledge of health insurance benefits and lack of access to health care in Saudi Arabia.

PubMed

Alkhamis, Abdulwahab A

2018-03-15

Insufficient knowledge of health insurance benefits could be associated with lack of access to health care, particularly for minority populations. This study aims to assess the association between expatriates' knowledge of health insurance benefits and lack of access to health care. A cross-sectional study design was conducted from March 2015 to February 2016 among 3398 insured male expatriates in Riyadh, Saudi Arabia. The dependent variable was binary and expresses access or lack of access to health care. Independent variables included perceived and validated knowledge of health insurance benefits and other variables. Data were summarized by computing frequencies and percentage of all quantities of variables. To evaluate variations in knowledge, personal and job characteristics with lack of access to health care, the Chi square test was used. Odds ratio (OR) and 95% confidence interval (CI) were recorded for each independent variable. Multiple logistic regression and stepwise logistic regression were performed and adjusted ORs were extracted. Descriptive analysis showed that 15% of participants lacked access to health care. The majority of these were unskilled laborers, usually with no education (17.5%), who had been working for less than 3 years (28.1%) in Saudi Arabia. A total of 23.3% worked for companies with less than 50 employees and 16.5% earned less than 4500 Saudi Riyals monthly ($1200). Many (20.3%) were young (< 30 years old) or older (17.9% ≥ 56 years old) and had no formal education (24.7%). Nearly half had fair or poor health status (49.5%), were uncomfortable conversing in Arabic (29.7%) or English (16.7%) and lacked previous knowledge of health insurance (18%). For perceived knowledge of health insurance, 55.2% scored 1 or 0 from total of 3. For validated knowledge, 16.9% scored 1 or 0 from total score of 4. Multiple logistic regression analysis showed that only perceived knowledge of health insurance had significant associations with lack of access to health care ((OR) = 0.393, (CI) = 0.335-0.461), but the result was insignificant for validated knowledge. Stepwise logistic regression gave similar findings. Our results confirmed that low perceived knowledge of health insurance in expatriates was associated with less access to health care.

Prevalence of "HIV/AIDS related" parental death and its association with sexual behavior of secondary school youth in Addis Ababa, Ethiopia: a cross sectional study.

PubMed

Menna, Takele; Ali, Ahmed; Worku, Alemayehu

2014-10-30

Human immunodeficiency virus infection is a global crisis that represents a serious health threat, particularly among younger people. Various studies show that both orphan and non-orphan adolescents and youths experience vulnerability to HIV. Nevertheless, the findings hitherto are mixed and inconclusive. The aim of this study, therefore, was to assess the prevalence of parental death and its association with multiple sexual partners among secondary school students for evidence based interventions. A cross-sectional study was conducted among secondary school youth in Addis Ababa, Ethiopia. A multistage sampling technique was used to select a representative sample of 2,169 school youths. Sexual health behavior related data were collected using self-administered questionnaire. Binary logistic regression was employed to examine the relation between parental death and multiple sexual partners. Among the 2,169 eligible study participants 1948 (90%) completed the self-administered questionnaires. Of those 1,182(60.7%) were females. The overall prevalence of parental death was 347(17.8%.) with 95% CI (16.2%, 19.6%). The HIV/AIDS proportionate mortality ratio was 28% (97/347).A multivariate logistic regression analysis showed that high HIV/AIDS related knowledge (AOR = 0.39; 95% CI, 0.18-0.84), positive attitude towards HIV prevention methods (AOR = 0.48; 95% CI, 0.23-0.97), being tested for HIV (AOR = 0.52; 95% CI, 0.31-0.87) and chewing Khat (AOR = 2.59; 95% CI,1.28-5.26)] were significantly associated with having multiple sexual partners among secondary school youths. Significant proportion of secondary school youths had lost at least one parent due to various causes. High knowledge of HIV/AIDS, positive attitude towards 'ABC' rules for HIV prevention, being tested for HIV and chewing khat are more likely to be factors associated with multiple sexual partnership among secondary school students in Addis Ababa.Therefore, the school based interventions against the HIV/AIDS epidemic should be strengthened with particular emphasis on the effects of HIV/AIDS related knowledge, attitude towards preventive measures, mechanisms for improving HIV Counseling and Testing coverage and the associated prevailing risk factors.

Stochastic Gravitational-Wave Background due to Primordial Binary Black Hole Mergers.

PubMed

Mandic, Vuk; Bird, Simeon; Cholis, Ilias

2016-11-11

Recent Advanced LIGO detections of binary black hole mergers have prompted multiple studies investigating the possibility that the heavy GW150914 binary system was of primordial origin, and hence could be evidence for dark matter in the form of black holes. We compute the stochastic background arising from the incoherent superposition of such primordial binary black hole systems in the Universe and compare it to the similar background spectrum due to binary black hole systems of stellar origin. We investigate the possibility of detecting this background with future gravitational-wave detectors, and conclude that constraining the dark matter component in the form of black holes using stochastic gravitational-wave background measurements will be very challenging.

Bayesian inference for unidirectional misclassification of a binary response trait.

PubMed

Xia, Michelle; Gustafson, Paul

2018-03-15

When assessing association between a binary trait and some covariates, the binary response may be subject to unidirectional misclassification. Unidirectional misclassification can occur when revealing a particular level of the trait is associated with a type of cost, such as a social desirability or financial cost. The feasibility of addressing misclassification is commonly obscured by model identification issues. The current paper attempts to study the efficacy of inference when the binary response variable is subject to unidirectional misclassification. From a theoretical perspective, we demonstrate that the key model parameters possess identifiability, except for the case with a single binary covariate. From a practical standpoint, the logistic model with quantitative covariates can be weakly identified, in the sense that the Fisher information matrix may be near singular. This can make learning some parameters difficult under certain parameter settings, even with quite large samples. In other cases, the stronger identification enables the model to provide more effective adjustment for unidirectional misclassification. An extension to the Poisson approximation of the binomial model reveals the identifiability of the Poisson and zero-inflated Poisson models. For fully identified models, the proposed method adjusts for misclassification based on learning from data. For binary models where there is difficulty in identification, the method is useful for sensitivity analyses on the potential impact from unidirectional misclassification. Copyright © 2017 John Wiley & Sons, Ltd.

America's Democracy Colleges: The Civic Engagement of Community College Students

ERIC Educational Resources Information Center

Angeli Newell, Mallory

2014-01-01

This study explored the civic engagement of current two- and four-year students to explore whether differences exist between the groups and what may explain the differences. Using binary logistic regression and Ordinary Least Squares regression it was found that community-based engagement was lower for two- than four-year students, though…

Attitudes towards Participation in Business Development Programmes: An Ethnic Comparison in Sweden

ERIC Educational Resources Information Center

Abbasian, Saeid; Yazdanfar, Darush

2015-01-01

Purpose: The aim of the study is to investigate whether there are any differences between the attitudes towards participation in development programmes of entrepreneurs who are immigrants and those who are native-born. Design/methodology/approach: Several statistical methods, including a binary logistic regression model, were used to analyse a…

2004 Carolyn Sherif Award Address: Heart Disease and Gender Inequity

ERIC Educational Resources Information Center

Travis, Cheryl Brown

2005-01-01

Individual patient records from the National Hospital Discharge Survey for 1988 and 1998 comprising approximately 10 million cases were the basis for a binary logistic regression model to predict coronary artery bypass graft. Patterns in 1988 and in 1998 indicated a dramatic and pernicious gender discrepancy in medical decisions involving bypass…

Factors Affecting Code Status in a University Hospital Intensive Care Unit

ERIC Educational Resources Information Center

Van Scoy, Lauren Jodi; Sherman, Michael

2013-01-01

The authors collected data on diagnosis, hospital course, and end-of-life preparedness in patients who died in the intensive care unit (ICU) with "full code" status (defined as receiving cardiopulmonary resuscitation), compared with those who didn't. Differences were analyzed using binary and stepwise logistic regression. They found no…

Logistic Map for Cancellable Biometrics

NASA Astrophysics Data System (ADS)

Supriya, V. G., Dr; Manjunatha, Ramachandra, Dr

2017-08-01

This paper presents design and implementation of secured biometric template protection system by transforming the biometric template using binary chaotic signals and 3 different key streams to obtain another form of template and demonstrating its efficiency by the results and investigating on its security through analysis including, key space analysis, information entropy and key sensitivity analysis.

Impact of Perceived Risk and Friend Influence on Alcohol and Marijuana Use among Students

ERIC Educational Resources Information Center

Merianos, Ashley L.; Rosen, Brittany L.; Montgomery, LaTrice; Barry, Adam E.; Smith, Matthew Lee

2017-01-01

We performed a secondary analysis of Adolescent Health Risk Behavior Survey data (N=937), examining associations between lifetime alcohol and marijuana use with intrapersonal (i.e., risk perceptions) and interpersonal (e.g., peer approval and behavior) factors. Multinomial and binary logistic regression analyses contend students reporting lifetime…

Comparison between students and residents on determinants of willingness to separate waste and waste separation behaviour in Zhengzhou, China.

PubMed

Dai, Xiaoping; Han, Yuping; Zhang, Xiaohong; Hu, Wei; Huang, Liangji; Duan, Wenpei; Li, Siyi; Liu, Xiaolu; Wang, Qian

2017-09-01

A better understanding of willingness to separate waste and waste separation behaviour can aid the design and improvement of waste management policies. Based on the intercept questionnaire survey data of undergraduate students and residents in Zhengzhou City of China, this article compared factors affecting the willingness and behaviour of students and residents to participate in waste separation using two binary logistic regression models. Improvement opportunities for waste separation were also discussed. Binary logistic regression results indicate that knowledge of and attitude to waste separation and acceptance of waste education significantly affect the willingness of undergraduate students to separate waste, and demographic factors, such as gender, age, education level, and income, significantly affect the willingness of residents to do so. Presence of waste-specific bins and attitude to waste separation are drivers of waste separation behaviour for both students and residents. Improved education about waste separation and facilities are effective to stimulate waste separation, and charging on unsorted waste may be an effective way to improve it in Zhengzhou.

Multidimensional Ultrasound Imaging of the Wrist: Changes of Shape and Displacement of the Median Nerve and Tendons in Carpal Tunnel Syndrome

PubMed Central

Filius, Anika; Scheltens, Marjan; Bosch, Hans G.; van Doorn, Pieter A.; Stam, Henk J.; Hovius, Steven E.R.; Amadio, Peter C.; Selles, Ruud W.

2015-01-01

Dynamics of structures within the carpal tunnel may alter in carpal tunnel syndrome (CTS) due to fibrotic changes and increased carpal tunnel pressure. Ultrasound can visualize these potential changes, making ultrasound potentially an accurate diagnostic tool. To study this, we imaged the carpal tunnel of 113 patients and 42 controls. CTS severity was classified according to validated clinical and nerve conduction study (NCS) classifications. Transversal and longitudinal displacement and shape (changes) were calculated for the median nerve, tendons and surrounding tissue. To predict diagnostic value binary logistic regression modeling was applied. Reduced longitudinal nerve displacement (p≤0.019), increased nerve cross-sectional area (p≤0.006) and perimeter (p≤0.007), and a trend of relatively changed tendon displacements were seen in patients. Changes were more convincing when CTS was classified as more severe. Binary logistic modeling to diagnose CTS using ultrasound showed a sensitivity of 70-71% and specificity of 80-84%. In conclusion, CTS patients have altered dynamics of structures within the carpal tunnel. PMID:25865180

Theoretical Models of Protostellar Binary and Multiple Systems with AMR Simulations

NASA Astrophysics Data System (ADS)

Matsumoto, Tomoaki; Tokuda, Kazuki; Onishi, Toshikazu; Inutsuka, Shu-ichiro; Saigo, Kazuya; Takakuwa, Shigehisa

2017-05-01

We present theoretical models for protostellar binary and multiple systems based on the high-resolution numerical simulation with an adaptive mesh refinement (AMR) code, SFUMATO. The recent ALMA observations have revealed early phases of the binary and multiple star formation with high spatial resolutions. These observations should be compared with theoretical models with high spatial resolutions. We present two theoretical models for (1) a high density molecular cloud core, MC27/L1521F, and (2) a protobinary system, L1551 NE. For the model for MC27, we performed numerical simulations for gravitational collapse of a turbulent cloud core. The cloud core exhibits fragmentation during the collapse, and dynamical interaction between the fragments produces an arc-like structure, which is one of the prominent structures observed by ALMA. For the model for L1551 NE, we performed numerical simulations of gas accretion onto protobinary. The simulations exhibit asymmetry of a circumbinary disk. Such asymmetry has been also observed by ALMA in the circumbinary disk of L1551 NE.

Widom Lines in Binary Mixtures of Supercritical Fluids.

PubMed

Raju, Muralikrishna; Banuti, Daniel T; Ma, Peter C; Ihme, Matthias

2017-06-08

Recent experiments on pure fluids have identified distinct liquid-like and gas-like regimes even under supercritical conditions. The supercritical liquid-gas transition is marked by maxima in response functions that define a line emanating from the critical point, referred to as Widom line. However, the structure of analogous state transitions in mixtures of supercritical fluids has not been determined, and it is not clear whether a Widom line can be identified for binary mixtures. Here, we present first evidence for the existence of multiple Widom lines in binary mixtures from molecular dynamics simulations. By considering mixtures of noble gases, we show that, depending on the phase behavior, mixtures transition from a liquid-like to a gas-like regime via distinctly different pathways, leading to phase relationships of surprising complexity and variety. Specifically, we show that miscible binary mixtures have behavior analogous to a pure fluid and the supercritical state space is characterized by a single liquid-gas transition. In contrast, immiscible binary mixture undergo a phase separation in which the clusters transition separately at different temperatures, resulting in multiple distinct Widom lines. The presence of this unique transition behavior emphasizes the complexity of the supercritical state to be expected in high-order mixtures of practical relevance.

An optimal algorithm for reconstructing images from binary measurements

NASA Astrophysics Data System (ADS)

Yang, Feng; Lu, Yue M.; Sbaiz, Luciano; Vetterli, Martin

2010-01-01

We have studied a camera with a very large number of binary pixels referred to as the gigavision camera [1] or the gigapixel digital film camera [2, 3]. Potential advantages of this new camera design include improved dynamic range, thanks to its logarithmic sensor response curve, and reduced exposure time in low light conditions, due to its highly sensitive photon detection mechanism. We use maximum likelihood estimator (MLE) to reconstruct a high quality conventional image from the binary sensor measurements of the gigavision camera. We prove that when the threshold T is "1", the negative loglikelihood function is a convex function. Therefore, optimal solution can be achieved using convex optimization. Base on filter bank techniques, fast algorithms are given for computing the gradient and the multiplication of a vector and Hessian matrix of the negative log-likelihood function. We show that with a minor change, our algorithm also works for estimating conventional images from multiple binary images. Numerical experiments with synthetic 1-D signals and images verify the effectiveness and quality of the proposed algorithm. Experimental results also show that estimation performance can be improved by increasing the oversampling factor or the number of binary images.

CAFÉ-BEANS: An exhaustive hunt for high-mass binaries

NASA Astrophysics Data System (ADS)

Negueruela, I.; Maíz-Apellániz, J.; Simón-Díaz, S.; Alfaro, E. J.; Herrero, A.; Alonso, J.; Barbá, R.; Lorenzo, J.; Marco, A.; Monguió, M.; Morrell, N.; Pellerin, A.; Sota, A.; Walborn, N. R.

2015-05-01

CAFÉ-BEANS is an on-going survey running on the 2.2 m telescope at Calar Alto. For more than two years, CAFÉ-BEANS has been collecting high-resolution spectra of early-type stars with the aim of detecting and characterising spectroscopic binaries. The main goal of this project is a thorough characterisation of multiplicity in high-mass stars by detecting all spectroscopic and visual binaries in a large sample of Galactic O-type stars, and solving their orbits. Our final objective is eliminating all biases in the high-mass-star IMF created by undetected binaries.

A comparison of clinical characteristics of older adults treated with antidepressants in general and psychiatric hospitals in Asia.

PubMed

Wang, Yuan-Yuan; Xiang, Yu-Tao; Ungvari, Gabor S; Ng, Chee H; Chiu, Helen F K; Yim, Larina C L; Si, Tian-Mei; Chee, Kok-Yoon; Avasthi, Ajit; Grover, Sandeep; Chong, Mian-Yoon; Sim, Kang; Kanba, Shigenobu; He, Yan-Ling; Lee, Min-Soo; Yang, Shu-Yu; Udomratn, Pichet; Kallivayalil, Roy A; Tanra, Andi J; Maramis, Margarita M; Shen, Winston W; Sartorius, Norman; Mahendran, Rathi; Teng, Jia-Ying; Tan, Chay-Hoon; Shinfuku, Naotaka

2017-11-01

This study compared the demographics, clinical characteristics, and antidepressant prescription patterns between Asian patients aged 50 years and older attending psychiatric hospitals and those attending general hospitals. In total, 955 patients (604 in general hospitals, 351 in psychiatric hospitals) aged 50 years or older treated with antidepressants in 10 Asian countries and territories were examined. Patients' demographics, clinical features, and prescriptions of psychotropic drugs were recorded using a standardized protocol and data collection procedure. Binary logistic regression revealed that high income and diagnosis of schizophrenia were independently associated with psychiatric hospital treatment, whereas outpatient care, diagnosis of anxiety disorders, and multiple major medical conditions were independently associated with general hospital treatment. In addition, tetracyclic and noradrenergic and specific serotonergic antidepressants were more likely to be prescribed in general hospitals. Older adults treated with antidepressants showed different demographic and clinical features between general hospitals and psychiatric hospitals in Asia. © 2017 Japanese Psychogeriatric Society.

Association of BPD and IVH with early neutrophil and white counts in VLBW neonates with gestational age <32 weeks

PubMed Central

Palta, Mari; Sadek-Badawi, Mona; Carlton, David P

2008-01-01

Objectives To investigate associations between early low neutrophil count from routine blood samples, white blood count (WBC), pregnancy complications and neonatal outcomes for very low birth weight infants (VLBW ≤1500g) with gestational age <32 weeks. Patients and Methods Information was abstracted on all infants admitted to level III NICUs in Wisconsin 2003-2004. 1002 (78%) had differential and corrected total white counts within 2 ½ hours of birth. Data analyses included frequency tables, binary logistic, ordinal logistc and ordinary regression. Results Low neutrophil count (<1000/μL) was strongly associated with low WBC, pregnancy complications and antenatal steroids. Low neutrophil count predicted bronchopulmonary dysplasia severity level (BPD) (OR: 1.7, 95% CI: 1.1-2.7) and intraventricular hemorrhage (IVH) grade (OR: 2.2, 95% CI: 1.3-3.8). Conclusions Early neutrophil counts may have multiple causes interfering with their routine use as an inflammatory marker. Nonetheless, low neutrophil count has consistent independent associations with outcomes. PMID:18563166

Bayesian multivariate hierarchical transformation models for ROC analysis.

PubMed

O'Malley, A James; Zou, Kelly H

2006-02-15

A Bayesian multivariate hierarchical transformation model (BMHTM) is developed for receiver operating characteristic (ROC) curve analysis based on clustered continuous diagnostic outcome data with covariates. Two special features of this model are that it incorporates non-linear monotone transformations of the outcomes and that multiple correlated outcomes may be analysed. The mean, variance, and transformation components are all modelled parametrically, enabling a wide range of inferences. The general framework is illustrated by focusing on two problems: (1) analysis of the diagnostic accuracy of a covariate-dependent univariate test outcome requiring a Box-Cox transformation within each cluster to map the test outcomes to a common family of distributions; (2) development of an optimal composite diagnostic test using multivariate clustered outcome data. In the second problem, the composite test is estimated using discriminant function analysis and compared to the test derived from logistic regression analysis where the gold standard is a binary outcome. The proposed methodology is illustrated on prostate cancer biopsy data from a multi-centre clinical trial.

Bayesian multivariate hierarchical transformation models for ROC analysis

PubMed Central

O'Malley, A. James; Zou, Kelly H.

2006-01-01

SUMMARY A Bayesian multivariate hierarchical transformation model (BMHTM) is developed for receiver operating characteristic (ROC) curve analysis based on clustered continuous diagnostic outcome data with covariates. Two special features of this model are that it incorporates non-linear monotone transformations of the outcomes and that multiple correlated outcomes may be analysed. The mean, variance, and transformation components are all modelled parametrically, enabling a wide range of inferences. The general framework is illustrated by focusing on two problems: (1) analysis of the diagnostic accuracy of a covariate-dependent univariate test outcome requiring a Box–Cox transformation within each cluster to map the test outcomes to a common family of distributions; (2) development of an optimal composite diagnostic test using multivariate clustered outcome data. In the second problem, the composite test is estimated using discriminant function analysis and compared to the test derived from logistic regression analysis where the gold standard is a binary outcome. The proposed methodology is illustrated on prostate cancer biopsy data from a multi-centre clinical trial. PMID:16217836

Do ethnicity and polygyny contribute to justification of men beating women in Ghana?

PubMed

Amo-Adjei, Joshua; Tuoyire, Derek Anamaale

2016-01-01

Violence against intimate partners threatens public health and social cohesion, and its prevalence could increase with an attitude of justification of such violence. The objective of this article was to use religion and ethnicity as proxies for culture to examine Ghanaian women's acceptance of being beaten. We employed descriptive and binary logistic regression statistics applied to Multiple Indicator Cluster Survey data collected in 2011 in Ghana. With a weighted sample of 10,627 women, the findings revealed that more than half (59.83%, 95% confidence interval (CI) = 57.41%, 62.2%) of the respondents justified at least one form of intimate partner violence (IPV) or another and being a Mole-Dagbani (adjusted odds ratio [AOR] = 1.41; 95%; CI = 1.05, 1.90) and/or in a polygamous marriage/union (AOR = 1.22; 95% CI = 1.04, 1.420) were significant risk factors for justifying IPV. Activism in promoting IPV-free communities has to be group-specific to reach those in need of interventions.

Auditory processing and phonological awareness skills of five-year-old children with and without musical experience.

PubMed

Escalda, Júlia; Lemos, Stela Maris Aguiar; França, Cecília Cavalieri

2011-09-01

To investigate the relations between musical experience, auditory processing and phonological awareness of groups of 5-year-old children with and without musical experience. Participants were 56 5-year-old subjects of both genders, 26 in the Study Group, consisting of children with musical experience, and 30 in the Control Group, consisting of children without musical experience. All participants were assessed with the Simplified Auditory Processing Assessment and Phonological Awareness Test and the data was statistically analyzed. There was a statistically significant difference between the results of the sequential memory test for verbal and non-verbal sounds with four stimuli, phonological awareness tasks of rhyme recognition, phonemic synthesis and phonemic deletion. Analysis of multiple binary logistic regression showed that, with exception of the sequential verbal memory with four syllables, the observed difference in subjects' performance was associated with their musical experience. Musical experience improves auditory and metalinguistic abilities of 5-year-old children.

Non-cereal food consumption, food insecurity and nutritional status of children and mothers: a case study in Bangladesh.

PubMed

Rabiul, Islam G M; Jahangir, Alam M; Buysse, J

2012-04-01

The aim of this study is to investigate the effects of food insecurity derived from non-cereal food consumption on nutritional status of children and mothers in a poverty-prone region in Bangladesh. Data from the Bangladesh Nutritional Surveillance Project, 2005 of Helen Keller International were used to relate non-cereal food consumption and household food insecurity to nutritional status of children and their mothers. Multiple regressions were used to determine the association between the nutritional outcomes and the explanatory variables. In the case of binary and multi-level outcomes, logistic regressions were used as well. Non-cereal dietary diversity was found to have little predictive power on BMI and MUAC of mothers and on the nutritional status of the children. Maternal education is strongly associated with mothers' and children's nutritional status. Dietary diversity based on non-cereal food consumption can be a useful tool to investigate the nutritional status of poor households, but more studies are needed to verify these findings.

Modeling Polytomous Item Responses Using Simultaneously Estimated Multinomial Logistic Regression Models

ERIC Educational Resources Information Center

Anderson, Carolyn J.; Verkuilen, Jay; Peyton, Buddy L.

2010-01-01

Survey items with multiple response categories and multiple-choice test questions are ubiquitous in psychological and educational research. We illustrate the use of log-multiplicative association (LMA) models that are extensions of the well-known multinomial logistic regression model for multiple dependent outcome variables to reanalyze a set of…

Impact of different approaches of primary care mental health on the prevalence of mental disorders.

PubMed

Moscovici, Leonardo; de Azevedo-Marques, Joao Mazzoncini; Bolsoni, Lívia Maria; Rodrigues-Junior, Antonio Luiz; Zuardi, Antonio Waldo

2018-05-01

AimTo compare the impact of three different approaches to primary care mental health on the prevalence of mental disorders. Millions of people suffer from mental disorders. As entry point into the health service, primary healthcare plays an important role in providing mental health prevention and treatment. Random sample of households in three different areas of the city of Ribeirão Preto (state of São Paulo, Brazil) were selected, and 20 trained medical students conducted interviews using a mental health screening instrument, the Mini-Screening of Mental Disorders, and a socio-demographic datasheet. Primary care mental health was provided in each area through a specific approach. The influence of the area of residence and the socio-demographic variables on the prevalence of mental disorder was explored and analyzed by univariate binary logistic regression and then by a multiple logistic regression model.FindingsA total of 1545 subjects were interviewed. Comparison between the three areas showed a significantly higher number of people with mental disorders in the area covered by the primary care team that did not have physicians with specific primary care mental health training, even when this association was adjusted for the influence of age, education, and socio-economic status.Our results suggest that residing in areas with family physicians with mental health training is associated with a lower prevalence of mental disorders.

Family Medicine or Primary Care Residency Selection: Effects of Family Medicine Interest Groups, MD/MPH Dual Degrees, and Rural Medical Education.

PubMed

Wei McIntosh, Elizabeth; Morley, Christopher P

2016-05-01

If medical schools are to produce primary care physicians (family medicine, pediatrics, or general internal medicine), they must provide educational experiences that enable medical students to maintain existing or form new interests in such careers. This study examined three mechanisms for doing so, at one medical school: participation as an officer in a family medicine interest group (FMIG), completion of a dual medical/public health (MD/MPH) degree program, and participation in a rural medical education (RMED) clinical track. Specialty Match data for students who graduated from the study institution between 2006 and 2015 were included as dependent variables in bivariate analysis (c2) and logistic regression models, examining FMIG, MD/MPH, and RMED participation as independent predictors of specialty choice (family medicine yes/no, or any primary care (PC) yes/no), controlling for student demographic data. In bivariate c2 analyses, FMIG officership did not significantly predict matching with family medicine or any PC; RMED and MD/MPH education were significant predictors of both family medicine and PC. Binary logistic regression analyses replicated the bivariate findings, controlling for student demographics. Dual MD/MPH and rural medical education had stronger effects in producing primary care physicians than participation in a FMIG as an officer, at one institution. Further study at multiple institutions is warranted.

Self-declared stock ownership and association with positive trial outcome in randomized controlled trials with binary outcomes published in general medical journals: a cross-sectional study.

PubMed

Falk Delgado, Alberto; Falk Delgado, Anna

2017-07-26

Describe the prevalence and types of conflicts of interest (COI) in published randomized controlled trials (RCTs) in general medical journals with a binary primary outcome and assess the association between conflicts of interest and favorable outcome. Parallel-group RCTs with a binary primary outcome published in three general medical journals during 2013-2015 were identified. COI type, funding source, and outcome were extracted. Binomial logistic regression model was performed to assess association between COI and funding source with outcome. A total of 509 consecutive parallel-group RCTs were included in the study. COI was reported in 74% in mixed funded RCTs and in 99% in for-profit funded RCTs. Stock ownership was reported in none of the non-profit RCTs, in 7% of mixed funded RCTs, and in 50% of for-profit funded RCTs. Mixed-funded RCTs had employees from the funding company in 11% and for-profit RCTs in 76%. Multivariable logistic regression revealed that stock ownership in the funding company among any of the authors was associated with a favorable outcome (odds ratio = 3.53; 95% confidence interval = 1.59-7.86; p < 0.01). COI in for-profit funded RCTs is extensive, because the factors related to COI are not fully independent, a multivariable analysis should be cautiously interpreted. However, after multivariable adjustment only stock ownership from the funding company among authors is associated with a favorable outcome.

Generation of binary holograms for deep scenes captured with a camera and a depth sensor

NASA Astrophysics Data System (ADS)

Leportier, Thibault; Park, Min-Chul

2017-01-01

This work presents binary hologram generation from images of a real object acquired from a Kinect sensor. Since hologram calculation from a point-cloud or polygon model presents a heavy computational burden, we adopted a depth-layer approach to generate the holograms. This method enables us to obtain holographic data of large scenes quickly. Our investigations focus on the performance of different methods, iterative and noniterative, to convert complex holograms into binary format. Comparisons were performed to examine the reconstruction of the binary holograms at different depths. We also propose to modify the direct binary search algorithm to take into account several reference image planes. Then, deep scenes featuring multiple planes of interest can be reconstructed with better efficiency.

Binary Star Orbits. IV. Orbits of 18 Southern Interferometric Pairs

NASA Astrophysics Data System (ADS)

Mason, Brian D.; Hartkopf, William I.; Tokovinin, Andrei

2010-09-01

First orbits are presented for 3 interferometric pairs and revised solutions for 15 others, based in part on first results from a recently initiated program of speckle interferometric observations of neglected southern binaries. Eight of these systems contain additional components, with multiplicity ranging up to 6.

Pneumatic binary encoder replaces multiple solenoid system

NASA Technical Reports Server (NTRS)

1966-01-01

Pneumatic binary encoder replaces solenoid system in the pilot stage of a digital actuator. The encoder operates in flip-flop manner to valve gas at either high or low pressures. By rotating the disk in a pinion-to-encoding gear ratio, six to eight adder circuits may be operated from single encoder.

Summary goodness-of-fit statistics for binary generalized linear models with noncanonical link functions.

PubMed

Canary, Jana D; Blizzard, Leigh; Barry, Ronald P; Hosmer, David W; Quinn, Stephen J

2016-05-01

Generalized linear models (GLM) with a canonical logit link function are the primary modeling technique used to relate a binary outcome to predictor variables. However, noncanonical links can offer more flexibility, producing convenient analytical quantities (e.g., probit GLMs in toxicology) and desired measures of effect (e.g., relative risk from log GLMs). Many summary goodness-of-fit (GOF) statistics exist for logistic GLM. Their properties make the development of GOF statistics relatively straightforward, but it can be more difficult under noncanonical links. Although GOF tests for logistic GLM with continuous covariates (GLMCC) have been applied to GLMCCs with log links, we know of no GOF tests in the literature specifically developed for GLMCCs that can be applied regardless of link function chosen. We generalize the Tsiatis GOF statistic originally developed for logistic GLMCCs, (TG), so that it can be applied under any link function. Further, we show that the algebraically related Hosmer-Lemeshow (HL) and Pigeon-Heyse (J(2) ) statistics can be applied directly. In a simulation study, TG, HL, and J(2) were used to evaluate the fit of probit, log-log, complementary log-log, and log models, all calculated with a common grouping method. The TG statistic consistently maintained Type I error rates, while those of HL and J(2) were often lower than expected if terms with little influence were included. Generally, the statistics had similar power to detect an incorrect model. An exception occurred when a log GLMCC was incorrectly fit to data generated from a logistic GLMCC. In this case, TG had more power than HL or J(2) . © 2015 John Wiley & Sons Ltd/London School of Economics.

RED GIANTS IN ECLIPSING BINARY AND MULTIPLE-STAR SYSTEMS: MODELING AND ASTEROSEISMIC ANALYSIS OF 70 CANDIDATES FROM KEPLER DATA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaulme, P.; McKeever, J.; Rawls, M. L.

2013-04-10

Red giant stars are proving to be an incredible source of information for testing models of stellar evolution, as asteroseismology has opened up a window into their interiors. Such insights are a direct result of the unprecedented data from space missions CoRoT and Kepler as well as recent theoretical advances. Eclipsing binaries are also fundamental astrophysical objects, and when coupled with asteroseismology, binaries provide two independent methods to obtain masses and radii and exciting opportunities to develop highly constrained stellar models. The possibility of discovering pulsating red giants in eclipsing binary systems is therefore an important goal that could potentiallymore » offer very robust characterization of these systems. Until recently, only one case has been discovered with Kepler. We cross-correlate the detected red giant and eclipsing-binary catalogs from Kepler data to find possible candidate systems. Light-curve modeling and mean properties measured from asteroseismology are combined to yield specific measurements of periods, masses, radii, temperatures, eclipse timing variations, core rotation rates, and red giant evolutionary state. After using three different techniques to eliminate false positives, out of the 70 systems common to the red giant and eclipsing-binary catalogs we find 13 strong candidates (12 previously unknown) to be eclipsing binaries, one to be a non-eclipsing binary with tidally induced oscillations, and 10 more to be hierarchical triple systems, all of which include a pulsating red giant. The systems span a range of orbital eccentricities, periods, and spectral types F, G, K, and M for the companion of the red giant. One case even suggests an eclipsing binary composed of two red giant stars and another of a red giant with a {delta}-Scuti star. The discovery of multiple pulsating red giants in eclipsing binaries provides an exciting test bed for precise astrophysical modeling, and follow-up spectroscopic observations of many of the candidate systems are encouraged. The resulting highly constrained stellar parameters will allow, for example, the exploration of how binary tidal interactions affect pulsations when compared to the single-star case.« less

Predictors of Gender Inequalities in the Rank of Full Professor

ERIC Educational Resources Information Center

Heijstra, Thamar; Bjarnason, Thoroddur; Rafnsdóttir, Gudbjörg Linda

2015-01-01

This article examines whether age, work-related, and family-related predictors explain differences in the academic advancement of women and men in Iceland. Survey data were analyzed by binary logistic regression. The findings put that women climb the academic career ladder at a slower pace than men. This finding puts one of the widely known…

South Texas Mexican American Use of Traditional Folk and Mainstream Alternative Therapies

ERIC Educational Resources Information Center

Martinez, Leslie N.

2009-01-01

A telephone survey was conducted with a large sample of Mexican Americans from border (n = 1,001) and nonborder (n = 1,030) regions in Texas. Patterns of traditional folk and mainstream complementary and alternative medicine (CAM) use were analyzed with two binary logistic regressions, using gender, self-rated health, confidence in medical…

Propensity of University Students in the Region of Antofagasta, Chile to Create Enterprise

ERIC Educational Resources Information Center

Romani, Gianni; Didonet, Simone; Contuliano, Sue-Hellen; Portilla, Rodrigo

2013-01-01

The authors aim to discuss the propensity or intention to create enterprise among university students in the region of Antofagasta, Chile, and to analyze the factors that influence the step from desire to intention. 681 students were surveyed. The data were analyzed by binary logistical regression. The results show that curriculum is among the…

Using Multiple and Logistic Regression to Estimate the Median WillCost and Probability of Cost and Schedule Overrun for Program Managers

DTIC Science & Technology

2017-03-23

PUBLIC RELEASE; DISTRIBUTION UNLIMITED Using Multiple and Logistic Regression to Estimate the Median Will- Cost and Probability of Cost and... Cost and Probability of Cost and Schedule Overrun for Program Managers Ryan C. Trudelle Follow this and additional works at: https://scholar.afit.edu...afit.edu. Recommended Citation Trudelle, Ryan C., "Using Multiple and Logistic Regression to Estimate the Median Will- Cost and Probability of Cost and

Combining multiple decisions: applications to bioinformatics

NASA Astrophysics Data System (ADS)

Yukinawa, N.; Takenouchi, T.; Oba, S.; Ishii, S.

2008-01-01

Multi-class classification is one of the fundamental tasks in bioinformatics and typically arises in cancer diagnosis studies by gene expression profiling. This article reviews two recent approaches to multi-class classification by combining multiple binary classifiers, which are formulated based on a unified framework of error-correcting output coding (ECOC). The first approach is to construct a multi-class classifier in which each binary classifier to be aggregated has a weight value to be optimally tuned based on the observed data. In the second approach, misclassification of each binary classifier is formulated as a bit inversion error with a probabilistic model by making an analogy to the context of information transmission theory. Experimental studies using various real-world datasets including cancer classification problems reveal that both of the new methods are superior or comparable to other multi-class classification methods.

"TNOs are Cool": A survey of the trans-Neptunian region. XIII. Statistical analysis of multiple trans-Neptunian objects observed with Herschel Space Observatory

NASA Astrophysics Data System (ADS)

Kovalenko, I. D.; Doressoundiram, A.; Lellouch, E.; Vilenius, E.; Müller, T.; Stansberry, J.

2017-11-01

Context. Gravitationally bound multiple systems provide an opportunity to estimate the mean bulk density of the objects, whereas this characteristic is not available for single objects. Being a primitive population of the outer solar system, binary and multiple trans-Neptunian objects (TNOs) provide unique information about bulk density and internal structure, improving our understanding of their formation and evolution. Aims: The goal of this work is to analyse parameters of multiple trans-Neptunian systems, observed with Herschel and Spitzer space telescopes. Particularly, statistical analysis is done for radiometric size and geometric albedo, obtained from photometric observations, and for estimated bulk density. Methods: We use Monte Carlo simulation to estimate the real size distribution of TNOs. For this purpose, we expand the dataset of diameters by adopting the Minor Planet Center database list with available values of the absolute magnitude therein, and the albedo distribution derived from Herschel radiometric measurements. We use the 2-sample Anderson-Darling non-parametric statistical method for testing whether two samples of diameters, for binary and single TNOs, come from the same distribution. Additionally, we use the Spearman's coefficient as a measure of rank correlations between parameters. Uncertainties of estimated parameters together with lack of data are taken into account. Conclusions about correlations between parameters are based on statistical hypothesis testing. Results: We have found that the difference in size distributions of multiple and single TNOs is biased by small objects. The test on correlations between parameters shows that the effective diameter of binary TNOs strongly correlates with heliocentric orbital inclination and with magnitude difference between components of binary system. The correlation between diameter and magnitude difference implies that small and large binaries are formed by different mechanisms. Furthermore, the statistical test indicates, although not significant with the sample size, that a moderately strong correlation exists between diameter and bulk density. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Primordial black holes in globular clusters

NASA Technical Reports Server (NTRS)

Sigurdsson, Steinn; Hernquist, Lars

1993-01-01

It has recently been recognized that significant numbers of medium-mass back holes (of order 10 solar masses) should form in globular clusters during the early stages of their evolution. Here we explore the dynamical and observational consequences of the presence of such a primordial black-hole population in a globular cluster. The holes initially segregate to the cluster cores, where they form binary and multiple black-hole systems. The subsequent dynamical evolution of the black-hole population ejects most of the holes on a relatively short timescale: a typical cluster will retain between zero and four black holes in its core, and possibly a few black holes in its halo. The presence of binary, triple, and quadruple black-hole systems in cluster cores will disrupt main-sequence and giant stellar binaries; this may account for the observed anomalies in the distribution of binaries in globular clusters. Furthermore, tidal interactions between a multiple black-hole system and a red giant star can remove much of the red giant's stellar envelope, which may explain the puzzling absence of larger red giants in the cores of some very dense clusters.

Constraining the Statistics of Population III Binaries

NASA Technical Reports Server (NTRS)

Stacy, Athena; Bromm, Volker

2012-01-01

We perform a cosmological simulation in order to model the growth and evolution of Population III (Pop III) stellar systems in a range of host minihalo environments. A Pop III multiple system forms in each of the ten minihaloes, and the overall mass function is top-heavy compared to the currently observed initial mass function in the Milky Way. Using a sink particle to represent each growing protostar, we examine the binary characteristics of the multiple systems, resolving orbits on scales as small as 20 AU. We find a binary fraction of approx. 36, with semi-major axes as large as 3000 AU. The distribution of orbital periods is slightly peaked at approx. < 900 yr, while the distribution of mass ratios is relatively flat. Of all sink particles formed within the ten minihaloes, approx. 50 are lost to mergers with larger sinks, and 50 of the remaining sinks are ejected from their star-forming disks. The large binary fraction may have important implications for Pop III evolution and nucleosynthesis, as well as the final fate of the first stars.

Logistic Mixed Models to Investigate Implicit and Explicit Belief Tracking

PubMed Central

Lages, Martin; Scheel, Anne

2016-01-01

We investigated the proposition of a two-systems Theory of Mind in adults’ belief tracking. A sample of N = 45 participants predicted the choice of one of two opponent players after observing several rounds in an animated card game. Three matches of this card game were played and initial gaze direction on target and subsequent choice predictions were recorded for each belief task and participant. We conducted logistic regressions with mixed effects on the binary data and developed Bayesian logistic mixed models to infer implicit and explicit mentalizing in true belief and false belief tasks. Although logistic regressions with mixed effects predicted the data well a Bayesian logistic mixed model with latent task- and subject-specific parameters gave a better account of the data. As expected explicit choice predictions suggested a clear understanding of true and false beliefs (TB/FB). Surprisingly, however, model parameters for initial gaze direction also indicated belief tracking. We discuss why task-specific parameters for initial gaze directions are different from choice predictions yet reflect second-order perspective taking. PMID:27853440

SIM Lite Detection of Habitable Planets in P-Type Binary-Planetary Systems

NASA Technical Reports Server (NTRS)

Pan, Xiaopei; Shao, Michael; Shaklan, Stuart; Goullioud, Renaud

2010-01-01

Close binary stars like spectroscopic binaries create a completely different environment than single stars for the evolution of a protoplanetary disk. Dynamical interactions between one star and protoplanets in such systems provide more challenges for theorists to model giant planet migration and formation of multiple planets. For habitable planets the majority of host stars are in binary star systems. So far only a small amount of Jupiter-size planets have been discovered in binary stars, whose minimum separations are 20 AU and the median value is about 1000 AU (because of difficulties in radial velocity measurements). The SIM Lite mission, a space-based astrometric observatory, has a unique capability to detect habitable planets in binary star systems. This work analyzed responses of the optical system to the field stop for companion stars and demonstrated that SIM Lite can observe exoplanets in visual binaries with small angular separations. In particular we investigated the issues for the search for terrestrial planets in P-type binary-planetary systems, where the planets move around both stars in a relatively distant orbit.

Formation of wide binaries by turbulent fragmentation

NASA Astrophysics Data System (ADS)

Lee, Jeong-Eun; Lee, Seokho; Dunham, Michael M.; Tatematsu, Ken'ichi; Choi, Minho; Bergin, Edwin A.; Evans, Neal J.

2017-08-01

Understanding the formation of wide-binary systems of very low-mass stars (M ≤ 0.1 solar masses, M⊙) is challenging 1,2,3 . The most obvious route is through widely separated low-mass collapsing fragments produced by turbulent fragmentation of a molecular core4,5. However, close binaries or multiples from disk fragmentation can also evolve to wide binaries over a few initial crossing times of the stellar cluster through tidal evolution6. Finding an isolated low-mass wide-binary system in the earliest stage of formation, before tidal evolution could occur, would prove that turbulent fragmentation is a viable mechanism for (very) low-mass wide binaries. Here we report high-resolution ALMA observations of a known wide-separation protostellar binary, showing that each component has a circumstellar disk. The system is too young7 to have evolved from a close binary, and the disk axes are misaligned, providing strong support for the turbulent fragmentation model. Masses of both stars are derived from the Keplerian rotation of the disks; both are very low-mass stars.

Terrestrial Planet Formation in Binary Star Systems

NASA Technical Reports Server (NTRS)

Lissauer, Jack J.; Quintana, Elisa V.; Chambers, John; Duncan, Martin J.; Adams, Fred

2003-01-01

Most stars reside in multiple star systems; however, virtually all models of planetary growth have assumed an isolated single star. Numerical simulations of the collapse of molecular cloud cores to form binary stars suggest that disks will form within such systems. Observations indirectly suggest disk material around one or both components within young binary star systems. If planets form at the right places within such circumstellar disks, they can remain in stable orbits within the binary star systems for eons. We are simulating the late stages of growth of terrestrial planets within binary star systems, using a new, ultrafast, symplectic integrator that we have developed for this purpose. We show that the late stages of terrestrial planet formation can indeed take place in a wide variety of binary systems and we have begun to delineate the range of parameter space for which this statement is true. Results of our initial simulations of planetary growth around each star in the alpha Centauri system and other 'wide' binary systems, as well as around both stars in very close binary systems, will be presented.

Detecting nonsense for Chinese comments based on logistic regression

NASA Astrophysics Data System (ADS)

Zhuolin, Ren; Guang, Chen; Shu, Chen

2016-07-01

To understand cyber citizens' opinion accurately from Chinese news comments, the clear definition on nonsense is present, and a detection model based on logistic regression (LR) is proposed. The detection of nonsense can be treated as a binary-classification problem. Besides of traditional lexical features, we propose three kinds of features in terms of emotion, structure and relevance. By these features, we train an LR model and demonstrate its effect in understanding Chinese news comments. We find that each of proposed features can significantly promote the result. In our experiments, we achieve a prediction accuracy of 84.3% which improves the baseline 77.3% by 7%.

A SURVEY OF THE HIGH ORDER MULTIPLICITY OF NEARBY SOLAR-TYPE BINARY STARS WITH Robo-AO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riddle, Reed L.; Bui, Khanh; Dekany, Richard G.

2015-01-20

We conducted a survey of nearby binary systems composed of main sequence stars of spectral types F and G in order to improve our understanding of the hierarchical nature of multiple star systems. Using Robo-AO, the first robotic adaptive optics instrument, we collected high angular resolution images with deep and well-defined detection limits in the Sloan Digital Sky Survey i' band. A total of 695 components belonging to 595 systems were observed. We prioritized observations of faint secondary components with separations over 10'' to quantify the still poorly constrained frequency of their subsystems. Of the 214 secondaries observed, 39 containmore » such subsystems; 19 of those were discovered with Robo-AO. The selection-corrected frequency of secondary subsystems with periods from 10{sup 3.5} to 10{sup 5} days is 0.12 ± 0.03, the same as the frequency of such companions to the primary. Half of the secondary pairs belong to quadruple systems where the primary is also a close pair, showing that the presence of subsystems in both components of the outer binary is correlated. The relatively large abundance of 2+2 quadruple systems is a new finding, and will require more exploration of the formation mechanism of multiple star systems. We also targeted close binaries with periods less than 100 yr, searching for their distant tertiary components, and discovered 17 certain and 2 potential new triples. In a subsample of 241 close binaries, 71 have additional outer companions. The overall frequency of tertiary components is not enhanced, compared to all (non-binary) targets, but in the range of outer periods from 10{sup 6} to 10{sup 7.5} days (separations on the order of 500 AU), the frequency of tertiary components is 0.16 ± 0.03, exceeding the frequency of similar systems among all targets (0.09) by almost a factor of two. Measurements of binary stars with Robo-AO allowed us to compute first orbits for 9 pairs and to improve orbits of another 11 pairs.« less

Fundamental parameters of massive stars in multiple systems: The cases of HD 17505A and HD 206267A

NASA Astrophysics Data System (ADS)

Raucq, F.; Rauw, G.; Mahy, L.; Simón-Díaz, S.

2018-06-01

Context. Many massive stars are part of binary or higher multiplicity systems. The present work focusses on two higher multiplicity systems: HD 17505A and HD 206267A. Aims: Determining the fundamental parameters of the components of the inner binary of these systems is mandatory to quantify the impact of binary or triple interactions on their evolution. Methods: We analysed high-resolution optical spectra to determine new orbital solutions of the inner binary systems. After subtracting the spectrum of the tertiary component, a spectral disentangling code was applied to reconstruct the individual spectra of the primary and secondary. We then analysed these spectra with the non-LTE model atmosphere code CMFGEN to establish the stellar parameters and the CNO abundances of these stars. Results: The inner binaries of these systems have eccentric orbits with e 0.13 despite their relatively short orbital periods of 8.6 and 3.7 days for HD 17505Aa and HD 206267Aa, respectively. Slight modifications of the CNO abundances are found in both components of each system. The components of HD 17505Aa are both well inside their Roche lobe, whilst the primary of HD 206267Aa nearly fills its Roche lobe around periastron passage. Whilst the rotation of the primary of HD 206267Aa is in pseudo-synchronization with the orbital motion, the secondary displays a rotation rate that is higher. Conclusions: The CNO abundances and properties of HD 17505Aa can be explained by single star evolutionary models accounting for the effects of rotation, suggesting that this system has not yet experienced binary interaction. The properties of HD 206267Aa suggest that some intermittent binary interaction might have taken place during periastron passages, but is apparently not operating anymore. Based on observations collected with the TIGRE telescope (La Luz, Mexico), the 1.93 m telescope at Observatoire de Haute Provence (France), the Nordic Optical Telescope at the Observatorio del Roque de los Muchachos (La Palma, Spain), and the Canada-France-Hawaii telescope (Mauna Kea, Hawaii).

Association of Brain-Derived Neurotrophic Factor and Vitamin D with Depression and Obesity: A Population-Based Study.

PubMed

Goltz, Annemarie; Janowitz, Deborah; Hannemann, Anke; Nauck, Matthias; Hoffmann, Johanna; Seyfart, Tom; Völzke, Henry; Terock, Jan; Grabe, Hans Jörgen

2018-06-19

Depression and obesity are widespread and closely linked. Brain-derived neurotrophic factor (BDNF) and vitamin D are both assumed to be associated with depression and obesity. Little is known about the interplay between vitamin D and BDNF. We explored the putative associations and interactions between serum BDNF and vitamin D levels with depressive symptoms and abdominal obesity in a large population-based cohort. Data were obtained from the population-based Study of Health in Pomerania (SHIP)-Trend (n = 3,926). The associations of serum BDNF and vitamin D levels with depressive symptoms (measured using the Patient Health Questionnaire) were assessed with binary and multinomial logistic regression models. The associations of serum BDNF and vitamin D levels with obesity (measured by the waist-to-hip ratio [WHR]) were assessed with binary logistic and linear regression models with restricted cubic splines. Logistic regression models revealed inverse associations of vitamin D with depression (OR = 0.966; 95% CI 0.951-0.981) and obesity (OR = 0.976; 95% CI 0.967-0.985). No linear association of serum BDNF with depression or obesity was found. However, linear regression models revealed a U-shaped association of BDNF with WHR (p < 0.001). Vitamin D was inversely associated with depression and obesity. BDNF was associated with abdominal obesity, but not with depression. At the population level, our results support the relevant roles of vitamin D and BDNF in mental and physical health-related outcomes. © 2018 S. Karger AG, Basel.

Binary variable multiple-model multiple imputation to address missing data mechanism uncertainty: Application to a smoking cessation trial

PubMed Central

Siddique, Juned; Harel, Ofer; Crespi, Catherine M.; Hedeker, Donald

2014-01-01

The true missing data mechanism is never known in practice. We present a method for generating multiple imputations for binary variables that formally incorporates missing data mechanism uncertainty. Imputations are generated from a distribution of imputation models rather than a single model, with the distribution reflecting subjective notions of missing data mechanism uncertainty. Parameter estimates and standard errors are obtained using rules for nested multiple imputation. Using simulation, we investigate the impact of missing data mechanism uncertainty on post-imputation inferences and show that incorporating this uncertainty can increase the coverage of parameter estimates. We apply our method to a longitudinal smoking cessation trial where nonignorably missing data were a concern. Our method provides a simple approach for formalizing subjective notions regarding nonresponse and can be implemented using existing imputation software. PMID:24634315

Synthetic Survey of the Kepler Field

NASA Astrophysics Data System (ADS)

Wells, Mark; Prša, Andrej

2018-01-01

In the era of large scale surveys, including LSST and Gaia, binary population studies will flourish due to the large influx of data. In addition to probing binary populations as a function of galactic latitude, under-sampled groups such as low mass binaries will be observed at an unprecedented rate. To prepare for these missions, binary population simulations need to be carried out at high fidelity. These simulations will enable the creation of simulated data and, through comparison with real data, will allow the underlying binary parameter distributions to be explored. In order for the simulations to be considered robust, they should reproduce observed distributions accurately. To this end we have developed a simulator which takes input models and creates a synthetic population of eclipsing binaries. Starting from a galactic single star model, implemented using Galaxia, a code by Sharma et al. (2011), and applying observed multiplicity, mass-ratio, period, and eccentricity distributions, as reported by Raghavan et al. (2010), Duchêne & Kraus (2013), and Moe & Di Stefano (2017), we are able to generate synthetic binary surveys that correspond to any survey cadences. In order to calibrate our input models we compare the results of our synthesized eclipsing binary survey to the Kepler Eclipsing Binary catalog.

Effect of Placenta Previa on Preeclampsia

PubMed Central

Ying, Hao; Lu, Yi; Dong, Yi-Nuo; Wang, De-Fen

2016-01-01

Background The correlation between gestational hypertension-preeclampsia (GH-PE) and placenta previa (PP) is controversial. Specifically, it is unknown whether placenta previa has any effect on the various types of preeclampsia (PE), and the role PP with concurrent placenta accreta (PA) play in the occurrence of GH-PE are not well understood. Objective The aim of this study was to identify the effects of PP on GH, mild and severe preeclampsia (MPE and SPE), and early- and late-onset preeclampsia (EPE and LPE). Another aim of the study was to determine if concurrent PA impacts the relationship between PP and GH-PE. Methods A retrospective single-center study of 1,058 patients having singleton pregnancies with PP was performed, and 2,116 pregnant women were randomly included as controls. These cases were collected from a tertiary hospital and met the inclusion criteria for the study. Clinical information, including PP and the gestational age at the onset of GH-PE were collected. Binary and multiple logistic regression analyses were conducted after the confounding variables were controlled to assess the effects of PP on different types of GH-PE. Results There were 155 patients with GH-PE in the two groups. The incidences of GH-PE in the PP group and the control group were 2.5% (26/1058) and 6.1% (129/2116), respectively (P = 0.000). Binary and multiple regression analyses were conducted after controlling for confounding variables. Compared to the control group, in the PP group, the risk of GH-PE was reduced significantly by 78% (AOR: 0.216; 95% CI: 0.135–0.345); the risks of GH and PE were reduced by 55% (AOR: 0.451; 95% CI: 0.233–0.873) and 86% (AOR: 0.141; 95% CI: 0.073–0.271), respectively; the risks of MPE and SPE were reduced by 73% (AOR: 0.269; 95% CI: 0.087–0828) and 88% (AOR: 0.123; 95% CI: 0.055–0.279), respectively; and the risks of EPE and LPE were reduced by 95% (AOR: 0.047; 95% CI: 0.012–0.190) and 67% (AOR: 0.330; 95% CI: 0.153–0.715), respectively. The incidence of concurrent PA in women with PP was 5.86%; PP with PA did not significantly further reduce the incidence of GH-PE compared with PP without PA (1.64% vs. 2.51%, P>0.05). Binary logistic regression analyses were conducted after controlling for confounding variables, compared with the non-PP + GH-PE group, and the AOR of FGR in the non-PP + non-GH-PE group was 0.206 (0.124–0.342). Compared with the PP + GH-PE group, the AOR of FGR in the PP + non-GH-PE group was 0.430 (0.123–1.500). Conclusion PP is not only associated with a significant reduction in the incidence of GH-PE, but also is associated with a reduction in incidence of various types of PE. Concurrent PA and PP do not show association with a reduction in incidence of GH-PE. PMID:26731265

Predicting the occurrence of wildfires with binary structured additive regression models.

PubMed

Ríos-Pena, Laura; Kneib, Thomas; Cadarso-Suárez, Carmen; Marey-Pérez, Manuel

2017-02-01

Wildfires are one of the main environmental problems facing societies today, and in the case of Galicia (north-west Spain), they are the main cause of forest destruction. This paper used binary structured additive regression (STAR) for modelling the occurrence of wildfires in Galicia. Binary STAR models are a recent contribution to the classical logistic regression and binary generalized additive models. Their main advantage lies in their flexibility for modelling non-linear effects, while simultaneously incorporating spatial and temporal variables directly, thereby making it possible to reveal possible relationships among the variables considered. The results showed that the occurrence of wildfires depends on many covariates which display variable behaviour across space and time, and which largely determine the likelihood of ignition of a fire. The joint possibility of working on spatial scales with a resolution of 1 × 1 km cells and mapping predictions in a colour range makes STAR models a useful tool for plotting and predicting wildfire occurrence. Lastly, it will facilitate the development of fire behaviour models, which can be invaluable when it comes to drawing up fire-prevention and firefighting plans. Copyright © 2016 Elsevier Ltd. All rights reserved.

A fast and high performance multiple data integration algorithm for identifying human disease genes

PubMed Central

2015-01-01

Background Integrating multiple data sources is indispensable in improving disease gene identification. It is not only due to the fact that disease genes associated with similar genetic diseases tend to lie close with each other in various biological networks, but also due to the fact that gene-disease associations are complex. Although various algorithms have been proposed to identify disease genes, their prediction performances and the computational time still should be further improved. Results In this study, we propose a fast and high performance multiple data integration algorithm for identifying human disease genes. A posterior probability of each candidate gene associated with individual diseases is calculated by using a Bayesian analysis method and a binary logistic regression model. Two prior probability estimation strategies and two feature vector construction methods are developed to test the performance of the proposed algorithm. Conclusions The proposed algorithm is not only generated predictions with high AUC scores, but also runs very fast. When only a single PPI network is employed, the AUC score is 0.769 by using F2 as feature vectors. The average running time for each leave-one-out experiment is only around 1.5 seconds. When three biological networks are integrated, the AUC score using F3 as feature vectors increases to 0.830, and the average running time for each leave-one-out experiment takes only about 12.54 seconds. It is better than many existing algorithms. PMID:26399620

Multilevel joint competing risk models

NASA Astrophysics Data System (ADS)

Karunarathna, G. H. S.; Sooriyarachchi, M. R.

2017-09-01

Joint modeling approaches are often encountered for different outcomes of competing risk time to event and count in many biomedical and epidemiology studies in the presence of cluster effect. Hospital length of stay (LOS) has been the widely used outcome measure in hospital utilization due to the benchmark measurement for measuring multiple terminations such as discharge, transferred, dead and patients who have not completed the event of interest at the follow up period (censored) during hospitalizations. Competing risk models provide a method of addressing such multiple destinations since classical time to event models yield biased results when there are multiple events. In this study, the concept of joint modeling has been applied to the dengue epidemiology in Sri Lanka, 2006-2008 to assess the relationship between different outcomes of LOS and platelet count of dengue patients with the district cluster effect. Two key approaches have been applied to build up the joint scenario. In the first approach, modeling each competing risk separately using the binary logistic model, treating all other events as censored under the multilevel discrete time to event model, while the platelet counts are assumed to follow a lognormal regression model. The second approach is based on the endogeneity effect in the multilevel competing risks and count model. Model parameters were estimated using maximum likelihood based on the Laplace approximation. Moreover, the study reveals that joint modeling approach yield more precise results compared to fitting two separate univariate models, in terms of AIC (Akaike Information Criterion).

Determination of riverbank erosion probability using Locally Weighted Logistic Regression

NASA Astrophysics Data System (ADS)

Ioannidou, Elena; Flori, Aikaterini; Varouchakis, Emmanouil A.; Giannakis, Georgios; Vozinaki, Anthi Eirini K.; Karatzas, George P.; Nikolaidis, Nikolaos

2015-04-01

Riverbank erosion is a natural geomorphologic process that affects the fluvial environment. The most important issue concerning riverbank erosion is the identification of the vulnerable locations. An alternative to the usual hydrodynamic models to predict vulnerable locations is to quantify the probability of erosion occurrence. This can be achieved by identifying the underlying relations between riverbank erosion and the geomorphological or hydrological variables that prevent or stimulate erosion. Thus, riverbank erosion can be determined by a regression model using independent variables that are considered to affect the erosion process. The impact of such variables may vary spatially, therefore, a non-stationary regression model is preferred instead of a stationary equivalent. Locally Weighted Regression (LWR) is proposed as a suitable choice. This method can be extended to predict the binary presence or absence of erosion based on a series of independent local variables by using the logistic regression model. It is referred to as Locally Weighted Logistic Regression (LWLR). Logistic regression is a type of regression analysis used for predicting the outcome of a categorical dependent variable (e.g. binary response) based on one or more predictor variables. The method can be combined with LWR to assign weights to local independent variables of the dependent one. LWR allows model parameters to vary over space in order to reflect spatial heterogeneity. The probabilities of the possible outcomes are modelled as a function of the independent variables using a logistic function. Logistic regression measures the relationship between a categorical dependent variable and, usually, one or several continuous independent variables by converting the dependent variable to probability scores. Then, a logistic regression is formed, which predicts success or failure of a given binary variable (e.g. erosion presence or absence) for any value of the independent variables. The erosion occurrence probability can be calculated in conjunction with the model deviance regarding the independent variables tested. The most straightforward measure for goodness of fit is the G statistic. It is a simple and effective way to study and evaluate the Logistic Regression model efficiency and the reliability of each independent variable. The developed statistical model is applied to the Koiliaris River Basin on the island of Crete, Greece. Two datasets of river bank slope, river cross-section width and indications of erosion were available for the analysis (12 and 8 locations). Two different types of spatial dependence functions, exponential and tricubic, were examined to determine the local spatial dependence of the independent variables at the measurement locations. The results show a significant improvement when the tricubic function is applied as the erosion probability is accurately predicted at all eight validation locations. Results for the model deviance show that cross-section width is more important than bank slope in the estimation of erosion probability along the Koiliaris riverbanks. The proposed statistical model is a useful tool that quantifies the erosion probability along the riverbanks and can be used to assist managing erosion and flooding events. Acknowledgements This work is part of an on-going THALES project (CYBERSENSORS - High Frequency Monitoring System for Integrated Water Resources Management of Rivers). The project has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: THALES. Investing in knowledge society through the European Social Fund.

Predicting High School Students' Interest in Majoring in a STEM Field: Insight into High School Students' Postsecondary Plans

ERIC Educational Resources Information Center

Lichtenberger, Eric; George-Jackson, Casey

2013-01-01

This study examined how various individual, family, and school level contextual factors impact the likelihood of planning to major in one of the science, technology, engineering, or mathematics (STEM) fields for high school students. A binary logistic regression model was developed to determine the extent to which each of the covariates helped to…

Community-Based Juvenile Reentry Services: The Effects of Service Dosage on Juvenile and Adult Recidivism

ERIC Educational Resources Information Center

Abrams, Laura S.; Terry, Diane; Franke, Todd M.

2011-01-01

In this study the authors examined the influence of length of participation in a community-based reentry program on the odds of reconviction in the juvenile and adult criminal justice systems. A structured telephone survey of reentry program alumni was conducted with 75 transition-age (18-25 year-old) young men. Binary logistic regression analysis…

Predicators of Success for Undergraduate Students Reinstated after an Academic Dismissal at a Small Midwest Private University Campus

ERIC Educational Resources Information Center

Meador, Ryan E.

2012-01-01

This study examined students who successfully applied for reinstatement after being academically dismissed for the first time in order to discover indicators of future success. This study examined 666 students' appeals filed at the DeVry University Kansas City campus between 2004 and 2009. Binary logistic regression was used to discover if a…

Experiences That Predict Early Career Teacher Commitment to and Retention in High-Poverty Urban Schools

ERIC Educational Resources Information Center

Whipp, Joan L.; Geronime, Lara

2017-01-01

Correlation analysis was used to analyze what experiences before and during teacher preparation for 72 graduates of an urban teacher education program were associated with urban commitment, first job location, and retention in urban schools for 3 or more years. Binary logistic regression was then used to analyze whether urban K-12 schooling,…

Won't You Be My Neighbor? Using an Ecological Approach to Examine the Impact of Community on Revictimization

ERIC Educational Resources Information Center

Obasaju, Mayowa A.; Palin, Frances L.; Jacobs, Carli; Anderson, Page; Kaslow, Nadine J.

2009-01-01

An ecological model is used to explore the moderating effects of community-level variables on the relation between childhood sexual, physical, and emotional abuse and adult intimate partner violence (IPV) within a sample of 98 African American women from low incomes. Results from hierarchical, binary logistics regressions analyses show that…

The cost of acquiring public hunting access on family forests lands

Treesearch

Michael A. Kilgore; Stephanie A. Snyder; Joesph M. Schertz; Steven J. Taff

2008-01-01

To address the issue of declining access to private forest land in the United States for hunting, over 1,000 Minnesota family forest owners were surveyed to estimate the cost of acquiring non-exclusive public hunting access rights. The results indicate landowner interest in selling access rights is extremely modest. Using binary logistic regression, the mean annual...

Bayesian Analysis of Item Response Curves. Research Report 84-1. Mathematical Sciences Technical Report No. 132.

ERIC Educational Resources Information Center

Tsutakawa, Robert K.; Lin, Hsin Ying

Item response curves for a set of binary responses are studied from a Bayesian viewpoint of estimating the item parameters. For the two-parameter logistic model with normally distributed ability, restricted bivariate beta priors are used to illustrate the computation of the posterior mode via the EM algorithm. The procedure is illustrated by data…

Understanding the Gap between Cognitive Abilities and Daily Living Skills in Adolescents with Autism Spectrum Disorders with Average Intelligence

ERIC Educational Resources Information Center

Duncan, Amie W.; Bishop, Somer L.

2015-01-01

Daily living skills standard scores on the Vineland Adaptive Behavior Scales-2nd edition were examined in 417 adolescents from the Simons Simplex Collection. All participants had at least average intelligence and a diagnosis of autism spectrum disorder. Descriptive statistics and binary logistic regressions were used to examine the prevalence and…

Sociodemographic Barriers to Early Detection of Autism: Screening and Evaluation Using the M-CHAT, M-CHAT-R, and Follow-Up

ERIC Educational Resources Information Center

Khowaja, Meena K.; Hazzard, Ann P.; Robins, Diana L.

2015-01-01

Parents (n = 11,845) completed the Modified Checklist for Autism in Toddlers (or its latest revision) at pediatric visits. Using sociodemographic predictors of maternal education and race, binary logistic regressions were utilized to examine differences in autism screening, diagnostic evaluation participation rates and outcomes, and reasons for…

The Effect of Participating in Indiana's Twenty-First Century Scholars Program on College Enrollments

ERIC Educational Resources Information Center

Toutkoushian, Robert K.; Hossler, Don; DesJardins, Stephen L.; McCall, Brian; Gonzalez Canche, Manuel S.

2015-01-01

Our study adds to prior work on Indiana's Twenty-first Century Scholars(TFCS) program by focusing on whether participating in--rather than completing--the program affects the likelihood of students going to college and where they initially enrolled. We first employ binary and multinomial logistic regression to obtain estimates of the impact of the…

Evolving binary classifiers through parallel computation of multiple fitness cases.

PubMed

Cagnoni, Stefano; Bergenti, Federico; Mordonini, Monica; Adorni, Giovanni

2005-06-01

This paper describes two versions of a novel approach to developing binary classifiers, based on two evolutionary computation paradigms: cellular programming and genetic programming. Such an approach achieves high computation efficiency both during evolution and at runtime. Evolution speed is optimized by allowing multiple solutions to be computed in parallel. Runtime performance is optimized explicitly using parallel computation in the case of cellular programming or implicitly taking advantage of the intrinsic parallelism of bitwise operators on standard sequential architectures in the case of genetic programming. The approach was tested on a digit recognition problem and compared with a reference classifier.

Sample size adjustments for varying cluster sizes in cluster randomized trials with binary outcomes analyzed with second-order PQL mixed logistic regression.

PubMed

Candel, Math J J M; Van Breukelen, Gerard J P

2010-06-30

Adjustments of sample size formulas are given for varying cluster sizes in cluster randomized trials with a binary outcome when testing the treatment effect with mixed effects logistic regression using second-order penalized quasi-likelihood estimation (PQL). Starting from first-order marginal quasi-likelihood (MQL) estimation of the treatment effect, the asymptotic relative efficiency of unequal versus equal cluster sizes is derived. A Monte Carlo simulation study shows this asymptotic relative efficiency to be rather accurate for realistic sample sizes, when employing second-order PQL. An approximate, simpler formula is presented to estimate the efficiency loss due to varying cluster sizes when planning a trial. In many cases sampling 14 per cent more clusters is sufficient to repair the efficiency loss due to varying cluster sizes. Since current closed-form formulas for sample size calculation are based on first-order MQL, planning a trial also requires a conversion factor to obtain the variance of the second-order PQL estimator. In a second Monte Carlo study, this conversion factor turned out to be 1.25 at most. (c) 2010 John Wiley & Sons, Ltd.

Risk Factors of Subacute Thrombosis After Intracranial Stenting for Symptomatic Intracranial Arterial Stenosis.

PubMed

Sun, Xuan; Tong, Xu; Lo, Wai Ting; Mo, Dapeng; Gao, Feng; Ma, Ning; Wang, Bo; Miao, Zhongrong

2017-03-01

We aimed to explore the risk factors of subacute thrombosis (SAT) after intracranial stenting for patients with symptomatic intracranial arterial stenosis. From January to December 2013, all symptomatic intracranial arterial stenosis patients who underwent intracranial stenting in Beijing Tiantan Hospital were prospectively registered into this study. Baseline clinical features and operative data were compared in patients who developed SAT with those who did not. Binary logistic regression model was used to determine the risk factors associated with SAT. Of the 221 patients enrolled, 9 (4.1%) cases had SAT 2 to 8 days after stenting. Binary logistic analysis showed that SAT was related with tandem stenting (odds ratio [OR], 11.278; 95% confidence interval [CI], 2.422-52.519) and antiplatelet resistance (aspirin resistance: OR, 6.267; 95% CI, 1.574-24.952; clopidogrel resistance: OR, 15.526; 95% CI, 3.105-77.626; aspirin and clopidogrel resistance: OR, 12.246; 95% CI, 2.932-51.147; and aspirin or clopidogrel resistance: OR, 11.340; 95% CI, 2.282-56.344). Tandem stenting and antiplatelet resistance might contribute to the development of SAT after intracranial stenting in patients with symptomatic intracranial arterial stenosis. © 2017 American Heart Association, Inc.

Predicting the "graduate on time (GOT)" of PhD students using binary logistics regression model

NASA Astrophysics Data System (ADS)

Shariff, S. Sarifah Radiah; Rodzi, Nur Atiqah Mohd; Rahman, Kahartini Abdul; Zahari, Siti Meriam; Deni, Sayang Mohd

2016-10-01

Malaysian government has recently set a new goal to produce 60,000 Malaysian PhD holders by the year 2023. As a Malaysia's largest institution of higher learning in terms of size and population which offers more than 500 academic programmes in a conducive and vibrant environment, UiTM has taken several initiatives to fill up the gap. Strategies to increase the numbers of graduates with PhD are a process that is challenging. In many occasions, many have already identified that the struggle to get into the target set is even more daunting, and that implementation is far too ideal. This has further being progressing slowly as the attrition rate increases. This study aims to apply the proposed models that incorporates several factors in predicting the number PhD students that will complete their PhD studies on time. Binary Logistic Regression model is proposed and used on the set of data to determine the number. The results show that only 6.8% of the 2014 PhD students are predicted to graduate on time and the results are compared wih the actual number for validation purpose.

The likelihood of achieving quantified road safety targets: a binary logistic regression model for possible factors.

PubMed

Sze, N N; Wong, S C; Lee, C Y

2014-12-01

In past several decades, many countries have set quantified road safety targets to motivate transport authorities to develop systematic road safety strategies and measures and facilitate the achievement of continuous road safety improvement. Studies have been conducted to evaluate the association between the setting of quantified road safety targets and road fatality reduction, in both the short and long run, by comparing road fatalities before and after the implementation of a quantified road safety target. However, not much work has been done to evaluate whether the quantified road safety targets are actually achieved. In this study, we used a binary logistic regression model to examine the factors - including vehicle ownership, fatality rate, and national income, in addition to level of ambition and duration of target - that contribute to a target's success. We analyzed 55 quantified road safety targets set by 29 countries from 1981 to 2009, and the results indicate that targets that are in progress and with lower level of ambitions had a higher likelihood of eventually being achieved. Moreover, possible interaction effects on the association between level of ambition and the likelihood of success are also revealed. Copyright © 2014 Elsevier Ltd. All rights reserved.

A measurement of disorder in binary sequences

NASA Astrophysics Data System (ADS)

Gong, Longyan; Wang, Haihong; Cheng, Weiwen; Zhao, Shengmei

2015-03-01

We propose a complex quantity, AL, to characterize the degree of disorder of L-length binary symbolic sequences. As examples, we respectively apply it to typical random and deterministic sequences. One kind of random sequences is generated from a periodic binary sequence and the other is generated from the logistic map. The deterministic sequences are the Fibonacci and Thue-Morse sequences. In these analyzed sequences, we find that the modulus of AL, denoted by |AL | , is a (statistically) equivalent quantity to the Boltzmann entropy, the metric entropy, the conditional block entropy and/or other quantities, so it is a useful quantitative measure of disorder. It can be as a fruitful index to discern which sequence is more disordered. Moreover, there is one and only one value of |AL | for the overall disorder characteristics. It needs extremely low computational costs. It can be easily experimentally realized. From all these mentioned, we believe that the proposed measure of disorder is a valuable complement to existing ones in symbolic sequences.

A new method for constructing networks from binary data

NASA Astrophysics Data System (ADS)

van Borkulo, Claudia D.; Borsboom, Denny; Epskamp, Sacha; Blanken, Tessa F.; Boschloo, Lynn; Schoevers, Robert A.; Waldorp, Lourens J.

2014-08-01

Network analysis is entering fields where network structures are unknown, such as psychology and the educational sciences. A crucial step in the application of network models lies in the assessment of network structure. Current methods either have serious drawbacks or are only suitable for Gaussian data. In the present paper, we present a method for assessing network structures from binary data. Although models for binary data are infamous for their computational intractability, we present a computationally efficient model for estimating network structures. The approach, which is based on Ising models as used in physics, combines logistic regression with model selection based on a Goodness-of-Fit measure to identify relevant relationships between variables that define connections in a network. A validation study shows that this method succeeds in revealing the most relevant features of a network for realistic sample sizes. We apply our proposed method to estimate the network of depression and anxiety symptoms from symptom scores of 1108 subjects. Possible extensions of the model are discussed.

Deficit of Wide Binaries in the η Chamaeleontis Young Cluster

NASA Astrophysics Data System (ADS)

Brandeker, Alexis; Jayawardhana, Ray; Khavari, Parandis; Haisch, Karl E., Jr.; Mardones, Diego

2006-12-01

We have carried out a sensitive high-resolution imaging survey of stars in the young (6-8 Myr), nearby (97 pc) compact cluster around η Chamaeleontis to search for stellar and substellar companions. Our data were obtained using the NACO adaptive optics system on the ESO Very Large Telescope (VLT). Given its youth and proximity, any substellar companions are expected to be luminous, especially in the near-infrared, and thus easier to detect next to their parent stars. Here, we present VLT NACO adaptive optics imaging with companion detection limits for 17 η Cha cluster members, and follow-up VLT ISAAC near-infrared spectroscopy for companion candidates. The widest binary detected is ~0.2", corresponding to the projected separation 20 AU, despite our survey being sensitive down to substellar companions outside 0.3", and planetary-mass objects outside 0.5". This implies that the stellar companion probability outside 0.3" and the brown dwarf companion probability outside 0.5" are less than 0.16 with 95% confidence. We compare the wide binary frequency of η Cha to that of the similarly aged TW Hydrae association and estimate the statistical likelihood that the wide binary probability is equal in both groups to be less than 2×10-4. Even though the η Cha cluster is relatively dense, stellar encounters in its present configuration cannot account for the relative deficit of wide binaries. We thus conclude that the difference in wide binary probability in these two groups provides strong evidence for multiplicity properties being dependent on environment. In two appendices we derive the projected separation probability distribution for binaries, used to constrain physical separations from observed projected separations, and summarize statistical tools useful for multiplicity studies.

The self-calibration method for multiple systems at the CHARA Array

NASA Astrophysics Data System (ADS)

O'Brien, David

The self-calibration method, a new interferometric technique at the CHARA Array, has been used to derive orbits for several spectroscopic binaries. This method uses the wide component of a hierarchical triple system to calibrate visibility measurements of the triple's close binary system. At certain baselines and separations, the calibrator in one of these systems can be observed quasi-simultaneously with the target. Depending on the orientation of the CHARA observation baseline relative to the orientation of the wide orbit of the triple system, separated fringe packets may be observed. A sophisticated observing scheme must be put in place to ensure the existence of separated fringe packets on nights of observation. Prior to the onset of this project, the reduction of separated fringe packet data had never included the goal of deriving visibilities for both fringe packets, so new data reduction software has been written. Visibilities obtained with separated fringe packet data for the target close binary are run through both Monte Carlo simulations and grid search programs in order to determine the best-fit orbital elements of the close binary. Several targets have been observed in this fashion, and orbits have been derived for seven targets, including three new orbits. Derivation of the orbit of the close pair in a triple system allows for the calculation of the mutual inclination, which is the angle between the planes of the wide and close orbit. Knowledge of this quantity may give insight into the formation processes that create multiple star systems. INDEX WORDS: Long-baseline interferometry, Self calibration, Separated fringe packets, Triple systems, Close binaries, Multiple systems, Orbital parameters, Near-infrared interferometry

Optical gravitational lensing experiment: OGLE-1999-BUL-19 - the first multipeak parallax event

NASA Astrophysics Data System (ADS)

Smith, Martin C.; Mao, Shude; Woźniak, P.; Udalski, A.; Szymański, M.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Żebruń, K.

2002-10-01

We describe a highly unusual microlensing event, OGLE-1999-BUL-19. Unlike most standard microlensing events, this event exhibits multiple peaks in its light curve. The Einstein radius crossing time for this event is approximately 1 yr, which is unusually long. We show that the additional peaks in the light curve can be caused by the very small value for the relative transverse velocity of the lens projected on to the observer plane (). Since this value is significantly less than the speed of the orbit of the Earth around the Sun (v⊕~ 30km s-1), the motion of the Earth induces these multiple peaks in the light curve. This value for is the lowest velocity so far published and we believe that this is the first multiple-peak parallax event ever observed. We also found that the event can be somewhat better fitted by a rotating binary-source model, although this is to be expected since every parallax microlensing event can be exactly reproduced by a suitable binary-source model. A face-on rotating binary-lens model was also identified, but this provides a significantly worse fit. We conclude that the most likely cause for this multipeak behaviour is parallax microlensing rather than microlensing by a binary source. However, this event may be exhibiting a slight binary-source signature in addition to these parallax-induced multiple peaks. With spectroscopic observations it is possible to test this `parallax plus binary-source' hypothesis and (in the instance that the hypothesis turns out to be correct) to simultaneously fit both models and obtain a measurement of the lens mass. Furthermore, spectroscopic observations could also supply information regarding the lens properties, possibly providing another avenue for determining the lens mass. We also investigated the nature of the blending for this event, and found that the majority of the I-band blending is contributed by a source roughly aligned with the lensed source. This implies that most of the I-band blending is caused by light from the lens or a binary companion to the source. However, in the V band, there appears to be a second blended source 0.35 arcsec away from the lensed source. Hubble Space Telescope observations will be very useful for understanding the nature of the blends. We also suggest that a radial velocity survey of all parallax events will be very useful for further constraining the lensing kinematics and understanding the origins of these events and the excess of long events toward the bulge.

Categorical QSAR models for skin sensitization based on local lymph node assay measures and both ground and excited state 4D-fingerprint descriptors

NASA Astrophysics Data System (ADS)

Liu, Jianzhong; Kern, Petra S.; Gerberick, G. Frank; Santos-Filho, Osvaldo A.; Esposito, Emilio X.; Hopfinger, Anton J.; Tseng, Yufeng J.

2008-06-01

In previous studies we have developed categorical QSAR models for predicting skin-sensitization potency based on 4D-fingerprint (4D-FP) descriptors and in vivo murine local lymph node assay (LLNA) measures. Only 4D-FP derived from the ground state (GMAX) structures of the molecules were used to build the QSAR models. In this study we have generated 4D-FP descriptors from the first excited state (EMAX) structures of the molecules. The GMAX, EMAX and the combined ground and excited state 4D-FP descriptors (GEMAX) were employed in building categorical QSAR models. Logistic regression (LR) and partial least square coupled logistic regression (PLS-CLR), found to be effective model building for the LLNA skin-sensitization measures in our previous studies, were used again in this study. This also permitted comparison of the prior ground state models to those involving first excited state 4D-FP descriptors. Three types of categorical QSAR models were constructed for each of the GMAX, EMAX and GEMAX datasets: a binary model (2-state), an ordinal model (3-state) and a binary-binary model (two-2-state). No significant differences exist among the LR 2-state model constructed for each of the three datasets. However, the PLS-CLR 3-state and 2-state models based on the EMAX and GEMAX datasets have higher predictivity than those constructed using only the GMAX dataset. These EMAX and GMAX categorical models are also more significant and predictive than corresponding models built in our previous QSAR studies of LLNA skin-sensitization measures.

Catalogue of Exoplanets in Multiple-Star-Systems

NASA Astrophysics Data System (ADS)

Schwarz, Richard; Funk, Barbara; Bazsó, Ákos; Pilat-Lohinger, Elke

2017-07-01

Cataloguing the data of exoplanetary systems becomes more and more important, due to the fact that they conclude the observations and support the theoretical studies. Since 1995 there is a database which list most of the known exoplanets (The Extrasolar Planets Encyclopaedia is available at http://exoplanet.eu/ and described at Schneider et al. 2011). With the growing number of detected exoplanets in binary and multiple star systems it became more important to mark and to separate them into a new database. Therefore we started to compile a catalogue for binary and multiple star systems. Since 2013 the catalogue can be found at http://www.univie.ac.at/adg/schwarz/multiple.html (description can be found at Schwarz et al. 2016) which will be updated regularly and is linked to the Extrasolar Planets Encyclopaedia. The data of the binary catalogue can be downloaded as a file (.csv) and used for statistical purposes. Our database is divided into two parts: the data of the stars and the planets, given in a separate list. Every columns of the list can be sorted in two directions: ascending, meaning from the lowest value to the highest, or descending. In addition an introduction and help is also given in the menu bar of the catalogue including an example list.

Improving Predictions of Multiple Binary Models in ILP

PubMed Central

2014-01-01

Despite the success of ILP systems in learning first-order rules from small number of examples and complexly structured data in various domains, they struggle in dealing with multiclass problems. In most cases they boil down a multiclass problem into multiple black-box binary problems following the one-versus-one or one-versus-rest binarisation techniques and learn a theory for each one. When evaluating the learned theories of multiple class problems in one-versus-rest paradigm particularly, there is a bias caused by the default rule toward the negative classes leading to an unrealistic high performance beside the lack of prediction integrity between the theories. Here we discuss the problem of using one-versus-rest binarisation technique when it comes to evaluating multiclass data and propose several methods to remedy this problem. We also illustrate the methods and highlight their link to binary tree and Formal Concept Analysis (FCA). Our methods allow learning of a simple, consistent, and reliable multiclass theory by combining the rules of the multiple one-versus-rest theories into one rule list or rule set theory. Empirical evaluation over a number of data sets shows that our proposed methods produce coherent and accurate rule models from the rules learned by the ILP system of Aleph. PMID:24696657

Brown Dwarf Companion Frequencies and Dynamical Interactions

NASA Astrophysics Data System (ADS)

Sterzik, Michael F.; Durisen, Richard H.

2003-06-01

Numerical simulations are used to explore how gravitational interactions within young multiple star systems may determine the binary properties of brown dwarfs. We compare different scenarios for cluster formation and decay and find that brown dwarf binaries, although possible, generally have a low frequency. We also discuss the frequencies of brown dwarf companions to normal stars expected from these models.

Redundant binary number representation for an inherently parallel arithmetic on optical computers.

PubMed

De Biase, G A; Massini, A

1993-02-10

A simple redundant binary number representation suitable for digital-optical computers is presented. By means of this representation it is possible to build an arithmetic with carry-free parallel algebraic sums carried out in constant time and parallel multiplication in log N time. This redundant number representation naturally fits the 2's complement binary number system and permits the construction of inherently parallel arithmetic units that are used in various optical technologies. Some properties of this number representation and several examples of computation are presented.

Canonical multi-valued input Reed-Muller trees and forms

NASA Technical Reports Server (NTRS)

Perkowski, M. A.; Johnson, P. D.

1991-01-01

There is recently an increased interest in logic synthesis using EXOR gates. The paper introduces the fundamental concept of Orthogonal Expansion, which generalizes the ring form of the Shannon expansion to the logic with multiple-valued (mv) inputs. Based on this concept we are able to define a family of canonical tree circuits. Such circuits can be considered for binary and multiple-valued input cases. They can be multi-level (trees and DAG's) or flattened to two-level AND-EXOR circuits. Input decoders similar to those used in Sum of Products (SOP) PLA's are used in realizations of multiple-valued input functions. In the case of the binary logic the family of flattened AND-EXOR circuits includes several forms discussed by Davio and Green. For the case of the logic with multiple-valued inputs, the family of the flattened mv AND-EXOR circuits includes three expansions known from literature and two new expansions.

Singular Isothermal Disks and the Formation of Multiple Stars

NASA Technical Reports Server (NTRS)

Galli, Daniele; Shu, Frank H.; Laughlin, Gregory; Lizano, Susana; DeVincenzi, Donald (Technical Monitor)

2000-01-01

A crucial missing ingredient in previous theoretical studies of fragmentation is the inclusion of dynamically important levels of magnetic fields. As a minimal model for a candidate presursor to the formation of binary and multiple stars, we therefore consider the equilibrium configuration of isopedically magnetized, scale-free, singular isothermal disks, without the assumption of axial symmetry. We find that lopsided (M = 1) configurations exist at any dimensionless rotation rate, including zero. Multiple-lobed (M = 2, 3, 4, ...) configurations bifurcate from an underlying axisymmetric sequence at progressively higher dimensionless rates of rotation, but such nonaxisymmetric sequences always terminate in shockwaves before they have a chance to fission into separate bodies. We advance the hypothesis that binary and multiple star-formation from smooth (i.e., not highly turbulent) starting states that are supercritical but in unstable mechanical balance requires the rapid (i.e., dynamical) loss of magnetic flux at some stage of the ensuing gravitational collapse.

Keck Adaptive Optics Imaging of Nearby Young Stars: Detection of Close Multiple Systems

NASA Astrophysics Data System (ADS)

Brandeker, Alexis; Jayawardhana, Ray; Najita, Joan

2003-10-01

Using adaptive optics on the Keck II 10 m telescope on Mauna Kea, we have surveyed 24 of the nearest young stars known in search of close companions. Our sample includes members of the MBM 12 and TW Hydrae young associations and the classical T Tauri binary UY Aurigae in the Taurus star-forming region. We present relative photometry and accurate astrometry for 10 close multiple systems. The multiplicity frequency in the TW Hydrae and MBM 12 groups are high in comparison to other young regions, although the significance of this result is low because of the small number statistics. We resolve S18 into a triple system, including a tight 63 mas (projected separation of 17 AU at a distance of 275 pc) binary, for the first time, with a hierarchical configuration reminiscent of VW Chamaeleontis and T Tauri. Another tight binary in our sample-TWA 5Aab (54 mas or 3 AU at 55 pc)-offers the prospect of dynamical mass measurement using astrometric observations within a few years and thus could be important for testing pre-main-sequence evolutionary models. Our observations confirm with 9 σ confidence that the brown dwarf TWA 5B is bound to TWA 5A. We find that the flux ratio of UY Aur has changed dramatically, by more than a magnitude in the H band, possibly as a result of variable extinction. With the smaller flux difference, the system may once again become detectable as an optical binary, as it was at the time of its discovery in 1944. Taken together, our results demonstrate that adaptive optics on large telescopes is a powerful tool for detecting tight companions and thus exploring the frequency and configurations of close multiple systems.

A generation at risk: a cross-sectional study on HIV/AIDS knowledge, exposure to mass media, and stigmatizing behaviors among young women aged 15-24 years in Ghana.

PubMed

Asamoah, Charity Konadu; Asamoah, Benedict Oppong; Agardh, Anette

2017-01-01

HIV/AIDS stigmatizing behaviors are a huge barrier to early detection and treatment of individuals with the AIDS virus. HIV/AIDS stigma and related consequences are debilitating, especially for vulnerable populations. This study sought to assess whether young women's HIV/AIDS knowledge levels and exposure to mass media (television and radio) have an influence on their stigmatizing behaviors and role as agents of stigma towards individuals living with HIV and AIDS. The data used for this study originated from the Ghana Multiple Indicator Cluster Survey 2011. Binary and multiple (stepwise) logistic regression analyses were used to examine the associations between HIV/AIDS knowledge, frequency of exposure to mass media, and HIV/AIDS stigmatizing behaviors among young women aged 15-24 years in Ghana. Of the 3573 young women, 80% of 15-19-year-olds and 76% of 20-24-year-olds had at least one stigmatizing behavior towards persons living with HIV/AIDS (PLHA). Young women with increased knowledge regarding HIV/AIDS and frequent exposure to mass media (television and radio) had lesser tendency to stigmatize or act as agents of stigma towards PLHA (proportion with at least one stigmatizing behavior per subgroup - HIV/AIDS knowledge: those with highest knowledge score 579 [70.1%], those with lowest knowledge score 28 [90.3%]; mass media: those with daily exposure 562 [73.4%], those not exposed at all 249 [89.2%]). There was a graded negative 'exposure-response' association between the ranked variables: HIV/AIDS knowledge, mass media, and HIV/AIDS stigmatizing behaviors. The significant inverse association between HIV/AIDS knowledge, frequency of exposure to mass media, and HIV/AIDS stigmatizing behaviors persisted even after adjusting for all other covariates in the multiple logistic regression models. It is extremely important to increase HIV/AIDS-related knowledge and reduce stigma among young women in Ghana through targeted HIV/AIDS factual knowledge transfer. The use of mass media for communication of issues regarding HIV/AIDS, its mode of transmission, and associated stigma should be emphasized among women in Ghana.

The early-type multiple system QZ Carinae

NASA Astrophysics Data System (ADS)

Mayer, P.; Lorenz, R.; Drechsel, H.; Abseim, A.

2001-02-01

We present an analysis of the early-type quadruple system QZ Car, consisting of an eclipsing and a non-eclipsing binary. The spectroscopic investigation is based on new high dispersion echelle and CAT/CES spectra of H and He lines. The elements for the orbit of the non-eclipsing pair could be refined. Lines of the brighter component of the eclipsing binary were detected in near-quadrature spectra, while signatures of the fainter component could be identified in only few spectra. Lines of the primary component of the non-eclipsing pair and of both components of the eclipsing pair were found to be variable in position and strength; in particular, the He ii 4686 emission line of the brighter eclipsing component is strongly variable. An ephemeris for the eclipsing binary QZ Car valid at present was derived Prim. Min. = hel. JD 2448687.16 + 5fd9991 * E. The relative orbit of the two binary constituents of the multiple system is discussed. In contrast to earlier investigations we found radial velocity changes of the systemic velocities of both binaries, which were used - together with an O-C analysis of the expected light-time effect - to derive approximate parameters of the mutual orbit of the two pairs. It is shown that this orbit and the distance to QZ Car can be further refined by minima timing and interferometry. Based on observations collected at the European Southern Observatory, La Silla, Chile.

Use of conservative and surgical foot care in an inception cohort of patients with rheumatoid arthritis.

PubMed

Backhouse, Michael R; Keenan, Anne-Maree; Hensor, Elizabeth M A; Young, Adam; James, David; Dixey, Josh; Williams, Peter; Prouse, Peter; Gough, Andrew; Helliwell, Philip S; Redmond, Anthony C

2011-09-01

To describe conservative and surgical foot care in patients with RA in England and explore factors that predict the type of foot care received. Use of podiatry and type of foot surgery were outcomes recorded in an inception cohort involving nine rheumatology centres that recruited patients with RA between 1986 and 1998 across England. Associations between patient-specific factors and service use were identified using univariate logistic regression analyses. The independence of these associations was then verified through multiple binary logistic regression modelling. Data were collected on 1237 patients with RA [66.9% females, mean (s.d.) age at disease onset = 54.36 (14.18) years, median DAS = 4.09 (1st quartile = 3.04, 3rd quartile = 5.26), median HAQ = 1 (0.50, 1.63)]. Interventions involving the feet in the cohort were low with only 364 (30%) out of 1218 receiving podiatry and 47 (4%) out of 1237 patients having surgery. At baseline, female gender, increasing age at onset, being RF positive and higher DAS scores were each independently associated with increased odds of seeing a podiatrist. Gender, age of onset and baseline DAS were independently associated with the odds of having foot surgery. Despite the known high prevalence of foot pathologies in RA, only one-third of this cohort accessed podiatry. While older females were more likely to access podiatry care and younger patients surgery, the majority of the RA population did not access any foot care.

Deep Hashing for Scalable Image Search.

PubMed

Lu, Jiwen; Liong, Venice Erin; Zhou, Jie

2017-05-01

In this paper, we propose a new deep hashing (DH) approach to learn compact binary codes for scalable image search. Unlike most existing binary codes learning methods, which usually seek a single linear projection to map each sample into a binary feature vector, we develop a deep neural network to seek multiple hierarchical non-linear transformations to learn these binary codes, so that the non-linear relationship of samples can be well exploited. Our model is learned under three constraints at the top layer of the developed deep network: 1) the loss between the compact real-valued code and the learned binary vector is minimized, 2) the binary codes distribute evenly on each bit, and 3) different bits are as independent as possible. To further improve the discriminative power of the learned binary codes, we extend DH into supervised DH (SDH) and multi-label SDH by including a discriminative term into the objective function of DH, which simultaneously maximizes the inter-class variations and minimizes the intra-class variations of the learned binary codes with the single-label and multi-label settings, respectively. Extensive experimental results on eight widely used image search data sets show that our proposed methods achieve very competitive results with the state-of-the-arts.

Star formation history: Modeling of visual binaries

NASA Astrophysics Data System (ADS)

Gebrehiwot, Y. M.; Tessema, S. B.; Malkov, O. Yu.; Kovaleva, D. A.; Sytov, A. Yu.; Tutukov, A. V.

2018-05-01

Most stars form in binary or multiple systems. Their evolution is defined by masses of components, orbital separation and eccentricity. In order to understand star formation and evolutionary processes, it is vital to find distributions of physical parameters of binaries. We have carried out Monte Carlo simulations in which we simulate different pairing scenarios: random pairing, primary-constrained pairing, split-core pairing, and total and primary pairing in order to get distributions of binaries over physical parameters at birth. Next, for comparison with observations, we account for stellar evolution and selection effects. Brightness, radius, temperature, and other parameters of components are assigned or calculated according to approximate relations for stars in different evolutionary stages (main-sequence stars, red giants, white dwarfs, relativistic objects). Evolutionary stage is defined as a function of system age and component masses. We compare our results with the observed IMF, binarity rate, and binary mass-ratio distributions for field visual binaries to find initial distributions and pairing scenarios that produce observed distributions.

Magnetic Fields and Multiple Protostar Formation

NASA Astrophysics Data System (ADS)

Boss, A. P.

2001-12-01

Recent observations of star-forming regions suggest that binary and multiple young stars are the rule rather than the exception, and implicate fragmentation as the likely mechanism for their formation. Most numerical hydrodynamical calculations of fragmentation have neglected the possibly deleterious effects of magnetic fields, in spite of ample evidence for the importance of magnetic support of pre-collapse clouds. We present here the first numerical hydrodynamical survey of the full effects of magnetic fields on the collapse and fragmentation of dense cloud cores. The models are calculated with a three dimensional, finite differences code which solves the equations of hydrodynamics, gravitation, and radiative transfer in the Eddington and diffusion approximations. Magnetic field effects are included through two simple approximations: magnetic pressure is added to the gas pressure, and magnetic tension is approximated by gravity dilution once collapse is well underway. Ambipolar diffusion of the magnetic field leading to cloud collapse is treated approximately as well. Models are calculated for a variety of initial cloud density profiles, shapes, and rotation rates. We find that in spite of the inclusion of magnetic field effects, dense cloud cores are capable of fragmenting into binary and multiple protostar systems. Initially prolate clouds tend to fragment into binary protostars, while initially oblate clouds tend to fragment into multiple protostar systems containing a small number (of order four) of fragments. The latter are likely to be subject to rapid orbital evolution, with close encounters possibly leading to the ejection of fragments. Contrary to expectation, magnetic tension effects appear to enhance fragmentation, allowing lower mass fragments to form than would otherwise be possible, because magnetic tension helps to prevent a central density singularity from forming and producing a dominant single object. Magnetically-supported dense cloud cores thus seem to be capable of collapsing and fragmenting into sufficient numbers of binary and multiple protostar systems to be compatible with observations of the relative rarity of single protostars. This work was partially supported by NSF grants AST-9983530 and MRI-9976645.

Collapse and Fragmentation of Molecular Cloud Cores. VII. Magnetic Fields and Multiple Protostar Formation

NASA Astrophysics Data System (ADS)

Boss, Alan P.

2002-04-01

Recent observations of star-forming regions suggest that binary and multiple young stars are the rule rather than the exception and implicate fragmentation as the likely mechanism for their formation. Most numerical hydrodynamic calculations of fragmentation have neglected the possibly deleterious effects of magnetic fields, despite ample evidence for the importance of magnetic support of precollapse clouds. We present here the first numerical hydrodynamic survey of the collapse and fragmentation of initially magnetically supported clouds that takes into account several magnetic field effects in an approximate manner. The models are calculated with a three-dimensional, finite differences code that solves the equations of hydrodynamics, gravitation, and radiative transfer in the Eddington and diffusion approximations. Magnetic field effects are included through two simple approximations: magnetic pressure is added to the gas pressure, and magnetic tension is approximated by gravity dilution once collapse is well underway. Ambipolar diffusion of the magnetic field leading to cloud collapse is treated approximately as well. Models are calculated for a variety of initial cloud density profiles, shapes, and rotation rates. We find that in spite of the inclusion of magnetic field effects, dense cloud cores are capable of fragmenting into binary and multiple protostar systems. Initially prolate clouds tend to fragment into binary protostars, while initially oblate clouds tend to fragment into multiple protostar systems containing a small number (of the order of 4) of fragments. The latter are likely to be subject to rapid orbital evolution, with close encounters possibly leading to the ejection of fragments. Contrary to expectation, magnetic tension effects appear to enhance fragmentation, allowing lower mass fragments to form than would otherwise be possible, because magnetic tension helps to prevent a central density singularity from forming and producing a dominant single object. Magnetically supported dense cloud cores thus seem to be capable of collapsing and fragmenting into sufficient numbers of binary and multiple protostar systems to be compatible with observations of the relative rarity of single protostars.

Development of the gateway recycling cloning system for multiple linking of expression cassettes in a defined order, and direction on gateway compatible binary vectors.

PubMed

Kimura, Tetsuya; Nakao, Akihide; Murata, Sachiko; Kobayashi, Yasuyuki; Tanaka, Yuji; Shibahara, Kenta; Kawazu, Tetsu; Nakagawa, Tsuyoshi

2013-01-01

We developed the Gateway recycling cloning system, which allows multiple linking of expression cassettes by multiple rounds of the Gateway LR reaction. Employing this system, the recycling donor vector pRED419 was subjected to the first LR reaction with an attR1-attR2 type destination vector. Then conversion vector pCON was subjected to an LR reaction to restore the attR1-attR2 site on the destination vector for the next cloning cycle. By repetition of these two simple steps, we linked four expression cassettes of a reporter gene in Gateway binary vector pGWB1, introduced the constructs into tobacco BY-2 cells, and observed the expression of transgenes.

Logistic Stick-Breaking Process

PubMed Central

Ren, Lu; Du, Lan; Carin, Lawrence; Dunson, David B.

2013-01-01

A logistic stick-breaking process (LSBP) is proposed for non-parametric clustering of general spatially- or temporally-dependent data, imposing the belief that proximate data are more likely to be clustered together. The sticks in the LSBP are realized via multiple logistic regression functions, with shrinkage priors employed to favor contiguous and spatially localized segments. The LSBP is also extended for the simultaneous processing of multiple data sets, yielding a hierarchical logistic stick-breaking process (H-LSBP). The model parameters (atoms) within the H-LSBP are shared across the multiple learning tasks. Efficient variational Bayesian inference is derived, and comparisons are made to related techniques in the literature. Experimental analysis is performed for audio waveforms and images, and it is demonstrated that for segmentation applications the LSBP yields generally homogeneous segments with sharp boundaries. PMID:25258593

Estimating the Probability of Rare Events Occurring Using a Local Model Averaging.

PubMed

Chen, Jin-Hua; Chen, Chun-Shu; Huang, Meng-Fan; Lin, Hung-Chih

2016-10-01

In statistical applications, logistic regression is a popular method for analyzing binary data accompanied by explanatory variables. But when one of the two outcomes is rare, the estimation of model parameters has been shown to be severely biased and hence estimating the probability of rare events occurring based on a logistic regression model would be inaccurate. In this article, we focus on estimating the probability of rare events occurring based on logistic regression models. Instead of selecting a best model, we propose a local model averaging procedure based on a data perturbation technique applied to different information criteria to obtain different probability estimates of rare events occurring. Then an approximately unbiased estimator of Kullback-Leibler loss is used to choose the best one among them. We design complete simulations to show the effectiveness of our approach. For illustration, a necrotizing enterocolitis (NEC) data set is analyzed. © 2016 Society for Risk Analysis.

Completing the Remedial Sequence and College-Level Credit-Bearing Math: Comparing Binary, Cumulative, and Continuation Ratio Logistic Regression Models

ERIC Educational Resources Information Center

Davidson, J. Cody

2016-01-01

Mathematics is the most common subject area of remedial need and the majority of remedial math students never pass a college-level credit-bearing math class. The majorities of studies that investigate this phenomenon are conducted at community colleges and use some type of regression model; however, none have used a continuation ratio model. The…

Modeling Student Performance in Mathematics Using Binary Logistic Regression at Selected Secondary Schools a Case Study of Mtwara Municipality and Ilemela District

ERIC Educational Resources Information Center

Mabula, Salyungu

2015-01-01

This study investigated the performance of secondary school students in Mathematics at the Selected Secondary Schools in Mtwara Municipality and Ilemela District by Absenteeism, Conduct, Type of School and Gender as explanatory Factors. The data used in the study was collected from documented records of 250 form three students with 1:1 gender…

User’s Guide to Southeast Asia Combat Data

DTIC Science & Technology

1976-06-01

North latitude Binary coded decimal Bomb damage assessment Battle Damage Assessment and Reporting Team Brigade Basic encyclopedia A University of...and movement routes Bomb wing CALCOMP CANDLESTICK CAP CAP CAS CAS CAVD CBU , CBS California Computer Products, Inc. Call sign...Special Studies Group (a high-level Washington committee) WAC WBLC WIA WOLF WSE3 WWDMS WWMCCS W X World Aeronautical Chart Waterborne logistic

Factors That Contributed to Gifted Students' Success on STEM Pathways: The Role of Race, Personal Interests, and Aspects of High School Experience

ERIC Educational Resources Information Center

Steenbergen-Hu, Saiying; Olszewski-Kubilius, Paula

2017-01-01

In this study, we conducted binary logistic regression on survey data collected from 244 past participants of a Talent Search program who attended regular high schools but supplemented their regular high school education with enriched or accelerated math and science learning activities. The participants completed an online survey 4 to 6 years…

Sample size calculations for case-control studies

Cancer.gov

This R package can be used to calculate the required samples size for unconditional multivariate analyses of unmatched case-control studies. The sample sizes are for a scalar exposure effect, such as binary, ordinal or continuous exposures. The sample sizes can also be computed for scalar interaction effects. The analyses account for the effects of potential confounder variables that are also included in the multivariate logistic model.

Association Between Socio-Demographic Background and Self-Esteem of University Students.

PubMed

Haq, Muhammad Ahsan Ul

2016-12-01

The purpose of this study was to scrutinize self-esteem of university students and explore association of self-esteem with academic achievement, gender and other factors. A sample of 346 students was selected from Punjab University, Lahore Pakistan. Rosenberg self-esteem scale with demographic variables was used for data collection. Besides descriptive statistics, binary logistic regression and t test were used for analysing the data. Significant gender difference was observed, self-esteem was significantly higher in males than females. Logistic regression indicates that age, medium of instruction, family income, student monthly expenditures, GPA and area of residence has direct effect on self-esteem; while number of siblings showed an inverse effect.

glmnetLRC f/k/a lrc package: Logistic Regression Classification

DOE Office of Scientific and Technical Information (OSTI.GOV)

2016-06-09

Methods for fitting and predicting logistic regression classifiers (LRC) with an arbitrary loss function using elastic net or best subsets. This package adds additional model fitting features to the existing glmnet and bestglm R packages. This package was created to perform the analyses described in Amidan BG, Orton DJ, LaMarche BL, et al. 2014. Signatures for Mass Spectrometry Data Quality. Journal of Proteome Research. 13(4), 2215-2222. It makes the model fitting available in the glmnet and bestglm packages more general by identifying optimal model parameters via cross validation with an customizable loss function. It also identifies the optimal threshold formore » binary classification.« less

Is parenting style a predictor of suicide attempts in a representative sample of adolescents?

PubMed

Donath, Carolin; Graessel, Elmar; Baier, Dirk; Bleich, Stefan; Hillemacher, Thomas

2014-04-26

Suicidal ideation and suicide attempts are serious but not rare conditions in adolescents. However, there are several research and practical suicide-prevention initiatives that discuss the possibility of preventing serious self-harm. Profound knowledge about risk and protective factors is therefore necessary. The aim of this study is a) to clarify the role of parenting behavior and parenting styles in adolescents' suicide attempts and b) to identify other statistically significant and clinically relevant risk and protective factors for suicide attempts in a representative sample of German adolescents. In the years 2007/2008, a representative written survey of N = 44,610 students in the 9th grade of different school types in Germany was conducted. In this survey, the lifetime prevalence of suicide attempts was investigated as well as potential predictors including parenting behavior. A three-step statistical analysis was carried out: I) As basic model, the association between parenting and suicide attempts was explored via binary logistic regression controlled for age and sex. II) The predictive values of 13 additional potential risk/protective factors were analyzed with single binary logistic regression analyses for each predictor alone. Non-significant predictors were excluded in Step III. III) In a multivariate binary logistic regression analysis, all significant predictor variables from Step II and the parenting styles were included after testing for multicollinearity. Three parental variables showed a relevant association with suicide attempts in adolescents - (all protective): mother's warmth and father's warmth in childhood and mother's control in adolescence (Step I). In the full model (Step III), Authoritative parenting (protective: OR: .79) and Rejecting-Neglecting parenting (risk: OR: 1.63) were identified as significant predictors (p < .001) for suicidal attempts. Seven further variables were interpreted to be statistically significant and clinically relevant: ADHD, female sex, smoking, Binge Drinking, absenteeism/truancy, migration background, and parental separation events. Parenting style does matter. While children of Authoritative parents profit, children of Rejecting-Neglecting parents are put at risk - as we were able to show for suicide attempts in adolescence. Some of the identified risk factors contribute new knowledge and potential areas of intervention for special groups such as migrants or children diagnosed with ADHD.

Clostridium difficile binary toxin CDT

PubMed Central

Gerding, Dale N; Johnson, Stuart; Rupnik, Maja; Aktories, Klaus

2014-01-01

Binary toxin (CDT) is frequently observed in Clostridium difficile strains associated with increased severity of C. difficile infection (CDI). CDT belongs to the family of binary ADP-ribosylating toxins consisting of two separate toxin components: CDTa, the enzymatic ADP-ribosyltransferase which modifies actin, and CDTb which binds to host cells and translocates CDTa into the cytosol. CDTb is activated by serine proteases and binds to lipolysis stimulated lipoprotein receptor. ADP-ribosylation induces depolymerization of the actin cytoskeleton. Toxin-induced actin depolymerization also produces microtubule-based membrane protrusions which form a network on epithelial cells and increase bacterial adherence. Multiple clinical studies indicate an association between binary toxin genes in C. difficile and increased 30-d CDI mortality independent of PCR ribotype. Further studies including measures of binary toxin in stool, analyses of CDI mortality caused by CDT-producing strains, and examination of the relationship of CDT expression to TcdA and TcdB toxin variants and PCR ribotypes are needed. PMID:24253566

SPECKLE INTERFEROMETRY AT SOAR IN 2014

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokovinin, Andrei; Mason, Brian D.; Hartkopf, William I.

2015-08-15

The results of speckle interferometric observations at the Southern Astrophysical Research Telescope (SOAR) telescope in 2014 are given. A total of 1641 observations were taken, yielding 1636 measurements of 1218 resolved binary and multiple stars and 577 non-resolutions of 441 targets. We resolved for the first time 56 pairs, including some nearby astrometric or spectroscopic binaries and ten new subsystems in previously known visual binaries. The calibration of the data is checked by linear fits to the positions of 41 wide binaries observed at SOAR over several seasons. The typical calibration accuracy is 0.°1 in angle and 0.3% in pixelmore » scale, while the measurement errors are on the order of 3 mas. The new data are used here to compute 194 binary star orbits, 148 of which are improvements on previous orbital solutions and 46 are first-time orbits.« less

Equivalency for Father and Mother Ratings of the ADHD Symptoms

ERIC Educational Resources Information Center

Gomez, Rapson

2010-01-01

The study used multiple-group confirmatory factor analysis (CFA) and multiple indicators multiple causes (MIMIC) procedures to examine the measurement and construct equivalencies for father and mother ratings of ADHD symptoms, recoded as binary scores. Fathers (N = 387) and mothers (N = 411) rated their primary school-aged children on the…

A multiple maximum scatter difference discriminant criterion for facial feature extraction.

PubMed

Song, Fengxi; Zhang, David; Mei, Dayong; Guo, Zhongwei

2007-12-01

Maximum scatter difference (MSD) discriminant criterion was a recently presented binary discriminant criterion for pattern classification that utilizes the generalized scatter difference rather than the generalized Rayleigh quotient as a class separability measure, thereby avoiding the singularity problem when addressing small-sample-size problems. MSD classifiers based on this criterion have been quite effective on face-recognition tasks, but as they are binary classifiers, they are not as efficient on large-scale classification tasks. To address the problem, this paper generalizes the classification-oriented binary criterion to its multiple counterpart--multiple MSD (MMSD) discriminant criterion for facial feature extraction. The MMSD feature-extraction method, which is based on this novel discriminant criterion, is a new subspace-based feature-extraction method. Unlike most other subspace-based feature-extraction methods, the MMSD computes its discriminant vectors from both the range of the between-class scatter matrix and the null space of the within-class scatter matrix. The MMSD is theoretically elegant and easy to calculate. Extensive experimental studies conducted on the benchmark database, FERET, show that the MMSD out-performs state-of-the-art facial feature-extraction methods such as null space method, direct linear discriminant analysis (LDA), eigenface, Fisherface, and complete LDA.

Adolescents’ internalizing problems following traumatic brain injury are related to parents’ psychiatric symptoms

PubMed Central

Peterson, Robin L.; Kirkwood, Michael W.; Taylor, H. Gerry; Stancin, Terry; Brown, Tanya M.; Wade, Shari L.

2013-01-01

Background A small body of previous research has demonstrated that pediatric traumatic brain injury increases risk for internalizing problems, but findings have varied regarding their predictors and correlates. Methods We examined the level and correlates of internalizing symptoms in 130 teens who had sustained a complicated mild to severe TBI within the past 1 to 6 months. Internalizing problems were measured via both maternal and paternal report Child Behavior Checklist. We also measured family functioning, parent psychiatric symptoms, and post-injury teen neurocognitive function. Results Mean parental ratings of internalizing problems were within the normal range. Depending on informant, 22–26% of the sample demonstrated clinically elevated internalizing problems. In multiple and binary logistic regression models, only parent psychiatric symptoms consistently provided unique prediction of teen internalizing symptoms. For maternal but not paternal report, female gender was associated with greater internalizing problems. Conclusion Parent and teen emotional problems are associated following adolescent TBI. Possible reasons for this relationship, including the effects of TBI on the family unit, are discussed. PMID:22935574

Disparities in Confidence to Manage Chronic Diseases in Men.

PubMed

Elder, Keith; Gilbert, Keon; Hanke, Louise Meret; Dean, Caress; Rice, Shahida; Johns, Marquisha; Piper, Crystal; Wiltshire, Jacqueline; Moore, Tondra; Wang, Jing

2014-01-01

Chronic diseases are highly prevalent among men in the United States and chronic disease management is problematic for men, particularly for racial and ethnic minority men. This study examined the association between health information seeking and confidence to manage chronic diseases among men. Study data were drawn from the 2007 Health Tracking Household Survey and analyzed using multiple binary logistic regressions. The analytical sample included 2,653 men, 18 years and older with a chronic illness. Results: Health information seeking was not associated with confidence to manage chronic illnesses. African-American men had lower odds than White men to agree to take actions to prevent symptoms with their health. Hispanic men had lower odds than White men to agree to tell a doctor concerns they have, even when not asked. Racial and ethnic minority men with a chronic condition appear to be less confident to manage their health compared to white men. Chronic disease management needs greater exploration to understand the best ways to help racial and ethnic minority men successfully manage their chronic condition.

Cumulative traumas and psychosis: an analysis of the national comorbidity survey and the British Psychiatric Morbidity Survey.

PubMed

Shevlin, Mark; Houston, James E; Dorahy, Martin J; Adamson, Gary

2008-01-01

Previous research has shown that traumatic life events are associated with a diagnosis of psychosis. Rather than focus on particular events, this study aimed to estimate the effect of cumulative traumatic experiences on psychosis. The study was based on 2 large community samples (The National Comorbidity Survey [NCS], The British Psychiatric Morbidity Survey [BPMS]). All analyses were conducted using hierarchical binary logistic regression, with psychosis diagnosis as the dependent variable. Background demographic variables were included in the first block, in addition to alcohol/drug dependence and depression. A variable indicating the number of traumas experienced was entered in the second block. Experiencing 2 or more trauma types significantly predicted psychosis, and there appeared to be a dose-response type relationship. Particular traumatic experiences have been implicated in the etiology of psychosis. Consistent with previous research, molestation and physical abuse were significant predictors of psychosis using the NCS, whereas for the BPMS, serious injury or assault and violence in the home were statistically significant. This study indicated the added risk of multiple traumatic experiences.

Cumulative Traumas and Psychosis: an Analysis of the National Comorbidity Survey and the British Psychiatric Morbidity Survey

PubMed Central

Shevlin, Mark; Houston, James E.; Dorahy, Martin J.; Adamson, Gary

2008-01-01

Previous research has shown that traumatic life events are associated with a diagnosis of psychosis. Rather than focus on particular events, this study aimed to estimate the effect of cumulative traumatic experiences on psychosis. The study was based on 2 large community samples (The National Comorbidity Survey [NCS], The British Psychiatric Morbidity Survey [BPMS]). All analyses were conducted using hierarchical binary logistic regression, with psychosis diagnosis as the dependent variable. Background demographic variables were included in the first block, in addition to alcohol/drug dependence and depression. A variable indicating the number of traumas experienced was entered in the second block. Experiencing 2 or more trauma types significantly predicted psychosis, and there appeared to be a dose-response type relationship. Particular traumatic experiences have been implicated in the etiology of psychosis. Consistent with previous research, molestation and physical abuse were significant predictors of psychosis using the NCS, whereas for the BPMS, serious injury or assault and violence in the home were statistically significant. This study indicated the added risk of multiple traumatic experiences. PMID:17586579

Race, gender, class, and sexual orientation: intersecting axes of inequality and self-rated health in Canada

PubMed Central

2011-01-01

Background Intersectionality theory, a way of understanding social inequalities by race, gender, class, and sexuality that emphasizes their mutually constitutive natures, possesses potential to uncover and explicate previously unknown health inequalities. In this paper, the intersectionality principles of "directionality," "simultaneity," "multiplicativity," and "multiple jeopardy" are applied to inequalities in self-rated health by race, gender, class, and sexual orientation in a Canadian sample. Methods The Canadian Community Health Survey 2.1 (N = 90,310) provided nationally representative data that enabled binary logistic regression modeling on fair/poor self-rated health in two analytical stages. The additive stage involved regressing self-rated health on race, gender, class, and sexual orientation singly and then as a set. The intersectional stage involved consideration of two-way and three-way interaction terms between the inequality variables added to the full additive model created in the previous stage. Results From an additive perspective, poor self-rated health outcomes were reported by respondents claiming Aboriginal, Asian, or South Asian affiliations, lower class respondents, and bisexual respondents. However, each axis of inequality interacted significantly with at least one other: multiple jeopardy pertained to poor homosexuals and to South Asian women who were at unexpectedly high risks of fair/poor self-rated health and mitigating effects were experienced by poor women and by poor Asian Canadians who were less likely than expected to report fair/poor health. Conclusions Although a variety of intersections between race, gender, class, and sexual orientation were associated with especially high risks of fair/poor self-rated health, they were not all consistent with the predictions of intersectionality theory. I conclude that an intersectionality theory well suited for explicating health inequalities in Canada should be capable of accommodating axis intersections of multiple kinds and qualities. PMID:21241506

The Clustering of Lifestyle Behaviours in New Zealand and their Relationship with Optimal Wellbeing.

PubMed

Prendergast, Kate B; Mackay, Lisa M; Schofield, Grant M

2016-10-01

The purpose of this research was to determine (1) associations between multiple lifestyle behaviours and optimal wellbeing and (2) the extent to which five lifestyle behaviours-sleep, physical activity, sedentary behaviour, sugary drink consumption, and fruit and vegetable intake-cluster in a national sample. A national sample of New Zealand adults participated in a web-based wellbeing survey. Five lifestyle behaviours-sleep, physical activity, sedentary behaviour, sugary drink consumption, and fruit and vegetable intake-were dichotomised into healthy (meets recommendations) and unhealthy (does not meet recommendations) categories. Optimal wellbeing was calculated using a multi-dimensional flourishing scale, and binary logistic regression analysis was used to calculate the relationship between multiple healthy behaviours and optimal wellbeing. Clustering was examined by comparing the observed and expected prevalence rates (O/E) of healthy and unhealthy two-, three-, four-, and five-behaviour combinations. Data from 9425 participants show those engaging in four to five healthy behaviours (23 %) were 4.7 (95 % confidence interval (CI) 3.8-5.7) times more likely to achieve optimal wellbeing compared to those engaging in zero to one healthy behaviour (21 %). Clustering was observed for healthy (5 %, O/E 2.0, 95 % CI 1.8-2.2) and unhealthy (5 %, O/E 2.1, 95 % CI 1.9-2.3) five-behaviour combinations and for four- and three-behaviour combinations. At the two-behaviour level, healthy fruit and vegetable intake clustered with all behaviours, except sleep which did not cluster with any behaviour. Multiple lifestyle behaviours were positively associated with optimal wellbeing. The results show lifestyle behaviours cluster, providing support for multiple behaviour lifestyle-based interventions for optimising wellbeing.

Extreme gravity tests with gravitational waves from compact binary coalescences: (II) ringdown

NASA Astrophysics Data System (ADS)

Berti, Emanuele; Yagi, Kent; Yang, Huan; Yunes, Nicolás

2018-05-01

The LIGO/Virgo detections of binary black hole mergers marked a watershed moment in astronomy, ushering in the era of precision tests of Kerr dynamics. We review theoretical and experimental challenges that must be overcome to carry out black hole spectroscopy with present and future gravitational wave detectors. Among other topics, we discuss quasinormal mode excitation in binary mergers, astrophysical event rates, tests of black hole dynamics in modified theories of gravity, parameterized "post-Kerr" ringdown tests, exotic compact objects, and proposed data analysis methods to improve spectroscopic tests of Kerr dynamics by stacking multiple events.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokovinin, Andrei; Horch, Elliott P., E-mail: atokovinin@ctio.noao.edu, E-mail: horche2@southernct.edu

Statistical characterization of secondary subsystems in binaries helps to distinguish between various scenarios of multiple-star formation. The Differential Speckle Survey Instrument was used at the Gemini-N telescope for several hours in 2015 July to probe the binarity of 25 secondary components in nearby solar-type binaries. Six new subsystems were resolved, with meaningful detection limits for the remaining targets. The large incidence of secondary subsystems agrees with other similar studies. The newly resolved subsystem HIP 115417 Ba,Bb causes deviations in the observed motion of the outer binary from which an astrometric orbit of Ba,Bb with a period of 117 years ismore » deduced.« less

Close Binaries in the η Chamaeleontis Cluster

NASA Astrophysics Data System (ADS)

Köhler, Rainer; Petr-Gotzens, Monika G.

2002-11-01

We have used speckle interferometry and adaptive optics observations to search for multiple systems among 13 stars in the η Chamaeleontis cluster. We discovered two previously unknown subarcsecond binaries. Placing the components in infrared color-magnitude diagrams shows that most members of η Cha are coeval. Repeated observations of the binary RECX 1 allow us to determine a preliminary orbit and derive a system mass of about 2 Msolar. Based on observations obtained at the European Southern Observatory, La Silla, proposals 56.E-0197, 62.I-0399, 65.I-0350, 65.I-0086, 67.C-0354, and 68.C-0539.

Using a binary logistic regression method and GIS for evaluating and mapping the groundwater spring potential in the Sultan Mountains (Aksehir, Turkey)

NASA Astrophysics Data System (ADS)

Ozdemir, Adnan

2011-07-01

SummaryThe purpose of this study is to produce a groundwater spring potential map of the Sultan Mountains in central Turkey, based on a logistic regression method within a Geographic Information System (GIS) environment. Using field surveys, the locations of the springs (440 springs) were determined in the study area. In this study, 17 spring-related factors were used in the analysis: geology, relative permeability, land use/land cover, precipitation, elevation, slope, aspect, total curvature, plan curvature, profile curvature, wetness index, stream power index, sediment transport capacity index, distance to drainage, distance to fault, drainage density, and fault density map. The coefficients of the predictor variables were estimated using binary logistic regression analysis and were used to calculate the groundwater spring potential for the entire study area. The accuracy of the final spring potential map was evaluated based on the observed springs. The accuracy of the model was evaluated by calculating the relative operating characteristics. The area value of the relative operating characteristic curve model was found to be 0.82. These results indicate that the model is a good estimator of the spring potential in the study area. The spring potential map shows that the areas of very low, low, moderate and high groundwater spring potential classes are 105.586 km 2 (28.99%), 74.271 km 2 (19.906%), 101.203 km 2 (27.14%), and 90.05 km 2 (24.671%), respectively. The interpretations of the potential map showed that stream power index, relative permeability of lithologies, geology, elevation, aspect, wetness index, plan curvature, and drainage density play major roles in spring occurrence and distribution in the Sultan Mountains. The logistic regression approach has not yet been used to delineate groundwater potential zones. In this study, the logistic regression method was used to locate potential zones for groundwater springs in the Sultan Mountains. The evolved model was found to be in strong agreement with the available groundwater spring test data. Hence, this method can be used routinely in groundwater exploration under favourable conditions.

Relationship between serum bilirubin concentrations and diabetic nephropathy in Shanghai Han's patients with type 1 diabetes mellitus.

PubMed

Li, Xu; Zhang, Lei; Chen, Haibing; Guo, Kaifeng; Yu, Haoyong; Zhou, Jian; Li, Ming; Li, Qing; Li, Lianxi; Yin, Jun; Liu, Fang; Bao, Yuqian; Han, Junfeng; Jia, Weiping

2017-03-31

Recent studies highlight a negative association between total bilirubin concentrations and albuminuria in patients with type 2 diabetes mellitus. Our study evaluated the relationship between bilirubin concentrations and the prevalence of diabetic nephropathy (DN) in Chinese patients with type 1 diabetes mellitus (T1DM). A total of 258 patients with T1DM were recruited and bilirubin concentrations were compared between patients with or without diabetic nephropathy. Multiple stepwise regression analysis was used to examine the relationship between bilirubin concentrations and 24 h urinary microalbumin. Binary logistic regression analysis was performed to assess independent risk factors for diabetic nephropathy. Participants were divided into four groups according to the quartile of total bilirubin concentrations (Q1, 0.20-0.60; Q2, 0.60-0.80; Q3, 0.80-1.00; Q4, 1.00-1.90 mg/dL) and the chi-square test was used to compare the prevalence of DN in patients with T1DM. The median bilirubin level was 0.56 (interquartile: 0.43-0.68 mg/dL) in the DN group, significantly lower than in the non-DN group (0.70 [interquartile: 0.58-0.89 mg/dL], P < 0.001). Spearman's correlational analysis showed bilirubin concentrations were inversely correlated with 24 h urinary microalbumin (r = -0.13, P < 0.05) and multiple stepwise regression analysis showed bilirubin concentrations were independently associated with 24 h urinary microalbumin. In logistic regression analysis, bilirubin concentrations were significantly inversely associated with nephropathy. In addition, in stratified analysis, from the first to the fourth quartile group, increased bilirubin concentrations were associated with decreased prevalence of DN from 21.90% to 2.00%. High bilirubin concentrations are independently and negatively associated with albuminuria and the prevalence of DN in patients with T1DM.

Risk factors for porcine reproductive and respiratory syndrome outbreaks in Vietnamese small stock farms.

PubMed

Truong, V M; Gummow, B

2014-07-01

To examine risk factors that could have played a role in the 2010 porcine reproductive and respiratory syndrome (PRRS) outbreak in Yenhung district, Quangninh province, North-Vietnam, with the purpose of establishing why existing control measures implemented after previous outbreaks had failed to prevent further outbreaks. A case-control study was carried out in Yenhung district. Data were obtained by an interview-based questionnaire survey. The sampling unit was households, which equated to small-scale pig farms. A total of 150 case and 150 control households were selected at communes affected by the 2010 PRRS epidemic during April to June. Risk factors were analysed using binary logistic regression and unconditional multiple logistic regression. Households infected with PRRS were significantly associated with multiple variables belonging to three main groups: (1) location of the farms: i.e. farms positioned <1,000 m from a pig abattoir or within 500 m of local markets or 100 m of main roads; (2) farm management: i.e. where there was non-application of weekly farm disinfection, feeding uncooked swill, new introduction of purchased pigs without isolation, or usage of water from irrigation systems for raising pigs; (3) people and animal contact: i.e. where households kept animals with either no confinement or partial confinement, had visits by family members to other affected farms or had frequent visits by neighbours. The use of water from irrigation systems was found to be the risk factor most strongly associated with infected households in the 2010 outbreak (OR=22; 95% CI=12-42). The results show that the epidemiology of PRRS in Quangninh province was linked to sociological and cultural practices, and that effective PRRS control needs an integrated approach coupled with behavioural changes in the pig raising practices of the general public. Failure to recognise this could explain why further outbreaks have occurred.

The relationship between hemoglobin level and the type 1 diabetic nephropathy in Anhui Han's patients.

PubMed

Jiang, Jun; Lei, Lan; Zhou, Xiaowan; Li, Peng; Wei, Ren

2018-02-20

Recent studies have shown that low hemoglobin (Hb) level promote the progression of chronic kidney disease. This study assessed the relationship between Hb level and type 1 diabetic nephropathy (DN) in Anhui Han's patients. There were a total of 236 patients diagnosed with type 1 diabetes mellitus and (T1DM) seen between January 2014 and December 2016 in our centre. Hemoglobin levels in patients with DN were compared with those without DN. The relationship between Hb level and the urinary albumin-creatinine ratio (ACR) was examined by Spearman's correlational analysis and multiple stepwise regression analysis. The binary logistic multivariate regression analysis was performed to analyze the correlated factors for type 1 DN, calculate the Odds Ratio (OR) and 95%confidence interval (CI). The predicting value of Hb level for DN was evaluated by area under receiver operation characteristic curve (AUROC) for discrimination and Hosmer-Lemeshow goodness-of-fit test for calibration. The average Hb levels in the DN group (116.1 ± 20.8 g/L) were significantly lower than the non-DN group (131.9 ± 14.4 g/L) , P < 0.001. Hb levels were independently correlated with the urinary ACR in multiple stepwise regression analysis. The logistic multivariate regression analysis showed that the Hb level (OR: 0.936, 95% CI: 0.910 to 0.963, P < 0.001) was inversely correlated with DN in patients with T1DM. In sub-analysis, low Hb level (Hb < 120g/L in female, Hb < 130g/L in male) was still negatively associated with DN in patients with T1DM. The AUROC was 0.721 (95% CI: 0.655 to 0.787) in assessing the discrimination of the Hb level for DN. The value of P was 0.593 in Hosmer-Lemeshow goodness-of-fit test. In Anhui Han's patients with T1DM, the Hb level is inversely correlated with urinary ACR and DN. This article is protected by copyright. All rights reserved.

Singular Isothermal Disks. Paper 2; Nonaxiymmetric Bifurcations and Equilibria

NASA Technical Reports Server (NTRS)

Galli, Danielle; Shu, Frank H.; Laughlin, Gregory; Lizano, Susana

2000-01-01

We review the difficulties of the classical fission and fragmentation hypotheses for the formation of binary and multiple stars. A crucial missing ingredient in previous theoretical studies is the inclusion of dynamically important levels of magnetic fields. As a minimal model for a candidate presursor to the formation of binary and multiple stars, we therefore formulate and solve the problem of the equilibria of isopedically magnetized, singular isothermal disks, without the assumption of axial symmetry. Considerable analytical progress can be made if we restrict our attention to models that are scale-free, i.e., that have surface densities that vary inversely with distance omega from the rotation axis of the system. In agreement with earlier analysis by Syer and Tremaine, we find that lopsided (M = 1) configurations exist at any dimensionless rotation rate, including zero. Multiple-lobed (M = 2, 3, 4, ...) configurations bifurcate from an underlying axisymmetric sequence at progressively higher dimensionless rates of rotation, but such nonaxisymmetric sequences always terminate in shockwaves before they have a chance to fission into M = 2, 3, 4, ... separate bodies. On the basis of our experience in this paper, we advance the hypothesis that binary and multiple star-formation from smooth (i.e., not highly turbulent) starting states that are supercritical but in unstable mechanical balance requires the rapid (i.e., dynamical) loss of magnetic flux at some stage of the ensuing gravitational collapse.

Noise exposure-response relationships established from repeated binary observations: Modeling approaches and applications.

PubMed

Schäffer, Beat; Pieren, Reto; Mendolia, Franco; Basner, Mathias; Brink, Mark

2017-05-01

Noise exposure-response relationships are used to estimate the effects of noise on individuals or a population. Such relationships may be derived from independent or repeated binary observations, and modeled by different statistical methods. Depending on the method by which they were established, their application in population risk assessment or estimation of individual responses may yield different results, i.e., predict "weaker" or "stronger" effects. As far as the present body of literature on noise effect studies is concerned, however, the underlying statistical methodology to establish exposure-response relationships has not always been paid sufficient attention. This paper gives an overview on two statistical approaches (subject-specific and population-averaged logistic regression analysis) to establish noise exposure-response relationships from repeated binary observations, and their appropriate applications. The considerations are illustrated with data from three noise effect studies, estimating also the magnitude of differences in results when applying exposure-response relationships derived from the two statistical approaches. Depending on the underlying data set and the probability range of the binary variable it covers, the two approaches yield similar to very different results. The adequate choice of a specific statistical approach and its application in subsequent studies, both depending on the research question, are therefore crucial.

An appraisal of convergence failures in the application of logistic regression model in published manuscripts.

PubMed

Yusuf, O B; Bamgboye, E A; Afolabi, R F; Shodimu, M A

2014-09-01

Logistic regression model is widely used in health research for description and predictive purposes. Unfortunately, most researchers are sometimes not aware that the underlying principles of the techniques have failed when the algorithm for maximum likelihood does not converge. Young researchers particularly postgraduate students may not know why separation problem whether quasi or complete occurs, how to identify it and how to fix it. This study was designed to critically evaluate convergence issues in articles that employed logistic regression analysis published in an African Journal of Medicine and medical sciences between 2004 and 2013. Problems of quasi or complete separation were described and were illustrated with the National Demographic and Health Survey dataset. A critical evaluation of articles that employed logistic regression was conducted. A total of 581 articles was reviewed, of which 40 (6.9%) used binary logistic regression. Twenty-four (60.0%) stated the use of logistic regression model in the methodology while none of the articles assessed model fit. Only 3 (12.5%) properly described the procedures. Of the 40 that used the logistic regression model, the problem of convergence occurred in 6 (15.0%) of the articles. Logistic regression tends to be poorly reported in studies published between 2004 and 2013. Our findings showed that the procedure may not be well understood by researchers since very few described the process in their reports and may be totally unaware of the problem of convergence or how to deal with it.

Risk of Recurrence in Operated Parasagittal Meningiomas: A Logistic Binary Regression Model.

PubMed

Escribano Mesa, José Alberto; Alonso Morillejo, Enrique; Parrón Carreño, Tesifón; Huete Allut, Antonio; Narro Donate, José María; Méndez Román, Paddy; Contreras Jiménez, Ascensión; Pedrero García, Francisco; Masegosa González, José

2018-02-01

Parasagittal meningiomas arise from the arachnoid cells of the angle formed between the superior sagittal sinus (SSS) and the brain convexity. In this retrospective study, we focused on factors that predict early recurrence and recurrence times. We reviewed 125 patients with parasagittal meningiomas operated from 1985 to 2014. We studied the following variables: age, sex, location, laterality, histology, surgeons, invasion of the SSS, Simpson removal grade, follow-up time, angiography, embolization, radiotherapy, recurrence and recurrence time, reoperation, neurologic deficit, degree of dependency, and patient status at the end of follow-up. Patients ranged in age from 26 to 81 years (mean 57.86 years; median 60 years). There were 44 men (35.2%) and 81 women (64.8%). There were 57 patients with neurologic deficits (45.2%). The most common presenting symptom was motor deficit. World Health Organization grade I tumors were identified in 104 patients (84.6%), and the majority were the meningothelial type. Recurrence was detected in 34 cases. Time of recurrence was 9 to 336 months (mean: 84.4 months; median: 79.5 months). Male sex was identified as an independent risk for recurrence with relative risk 2.7 (95% confidence interval 1.21-6.15), P = 0.014. Kaplan-Meier curves for recurrence had statistically significant differences depending on sex, age, histologic type, and World Health Organization histologic grade. A binary logistic regression was made with the Hosmer-Lemeshow test with P > 0.05; sex, tumor size, and histologic type were used in this model. Male sex is an independent risk factor for recurrence that, associated with other factors such tumor size and histologic type, explains 74.5% of all cases in a binary regression model. Copyright © 2017 Elsevier Inc. All rights reserved.

Measurement of the Tidal Dissipation in Multiple Stars

NASA Astrophysics Data System (ADS)

Tokovinin, Andrei

2007-08-01

Considerable effort has been spent to date in measuring the period of tidal circularisation in close binaries as a function of age, in order to constrain the tidal dissipation theory. Here we evaluate a new, direct method of measuring the tidal dissipation by precise timings of periastron passages in a very eccentric binary. The example of the 41 Dra system is studied in some detail.

Vestibular evoked myogenic potentials and MRI in early multiple sclerosis: Validation of the VEMP score.

PubMed

Crnošija, Luka; Krbot Skorić, Magdalena; Gabelić, Tereza; Adamec, Ivan; Habek, Mario

2017-01-15

To validate the VEMP score as a measure of brainstem dysfunction in patients with the first symptom of multiple sclerosis (MS) (clinically isolated syndrome (CIS)) and to investigate the correlation between VEMP and brainstem MRI results. 121 consecutive CIS patients were enrolled and brainstem functional system score (BSFS) was determined. Ocular VEMP (oVEMP) and cervical VEMP (cVEMP) were analyzed for latencies, conduction block and amplitude asymmetry ratio and the VEMP score was calculated. MRI was analyzed for the presence of brainstem lesions as a whole and separately for the presence of pontine, midbrain and medulla oblongata lesions. Patients with signs of brainstem involvement during the neurological examination (with BSFS ≥1) had a higher oVEMP score compared to patients with no signs of brainstem involvement. A binary logistic regression model showed that patients with brainstem lesion on the MRI are 6.780 times more likely to have BSFS ≥1 (p=0.001); and also, a higher VEMP score is associated with BSFS ≥1 (p=0.042). Furthermore, significant correlations were found between clinical brainstem involvement and brainstem and pontine MRI lesions, and prolonged latencies and/or absent VEMP responses. The VEMP score is a valuable tool in evaluation of brainstem involvement in patients with early MS. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation on occupant injury severity in rear-end crashes involving trucks as the front vehicle in Beijing area, China.

PubMed

Yuan, Quan; Lu, Meng; Theofilatos, Athanasios; Li, Yi-Bing

2017-02-01

Rear-end crashes attribute to a large portion of total crashes in China, which lead to many casualties and property damage, especially when involving commercial vehicles. This paper aims to investigate the critical factors for occupant injury severity in the specific rear-end crash type involving trucks as the front vehicle (FV). This paper investigated crashes occurred from 2011 to 2013 in Beijing area, China and selected 100 qualified cases i.e., rear-end crashes involving trucks as the FV. The crash data were supplemented with interviews from police officers and vehicle inspection. A binary logistic regression model was used to build the relationship between occupant injury severity and corresponding affecting factors. Moreover, a multinomial logistic model was used to predict the likelihood of fatal or severe injury or no injury in a rear-end crash. The results provided insights on the characteristics of driver, vehicle and environment, and the corresponding influences on the likelihood of a rear-end crash. The binary logistic model showed that drivers' age, weight difference between vehicles, visibility condition and lane number of road significantly increased the likelihood for severe injury of rear-end crash. The multinomial logistic model and the average direct pseudo-elasticity of variables showed that night time, weekdays, drivers from other provinces and passenger vehicles as rear vehicles significantly increased the likelihood of rear drivers being fatal. All the abovementioned significant factors should be improved, such as the conditions of lighting and the layout of lanes on roads. Two of the most common driver factors are drivers' age and drivers' original residence. Young drivers and outsiders have a higher injury severity. Therefore it is imperative to enhance the safety education and management on the young drivers who steer heavy duty truck from other cities to Beijing on weekdays. Copyright © 2016 Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. Production and hosting by Elsevier B.V. All rights reserved.

Young Binaries and Early Stellar Evolution

NASA Astrophysics Data System (ADS)

Brandner, Wolfgang

1996-07-01

Most main-sequence stars are members of binary or multiple systems. The same is true for pre-main-sequence (PMS) stars, as recent surveys have shown. Therefore studying star formation means to a large extent studying the formation of binary systems. Similarly, studying early stellar evolution primarily involves PMS binary systems. In this thesis I have studied the binary frequency among ROSAT selected T Tauri stars in the Chamaeleon T association and the Scorpius-Centaurus OB association, and the evolutionary status of Hα-selected PMS binaries in the T associations of Chamaeleon, Lupus, and ρ Ophiuchi. The direct imaging and spectroscopic observations in the optical have been carried out under subarcsec seeing conditions at the ESO New Technology Telescope (NTT) at La Silla. Furthermore, high-spatial resolution images of selected PMS stars in the near infrared were obtained with the ESO adaptive optics system COME-ON+/ADONIS. Among 195 T Tauri stars observed using direct imaging 31 binaries could be identified, 12 of them with subarcsec separation. Based on statistical arguments alone I conclude that almost all of them are indeed physical (i.e. gravitationally bound) binary or multiple systems. Using astrometric measurements of some binaries I showed that the components of these binaries are common proper motion pairs, very likely in a gravitationally bound orbit around each other. The overall binary frequency among T Tauri stars with a range of separations between 120 and 1800 AU is in agreement with the binary frequency observed among main-sequence stars in the solar neighbourhood. However, within individual regions the spatial distribution of binaries is non-uniform. In particular, in Upper Scorpius, weak-line T Tauri stars in the vicinity of early type stars seem to be almost devoid of multiple systems, whereas in another area in Upper Scorpius half of all weak-line T Tauri stars have a companion in a range of separation between 0.''7 and 3.''0. For a sample of 14 spatially resolved PMS binaries (separations 0.''6 to 1.prime'7) located in the above mentioned T associations both photometric and spectroscopic information has been analyzed. All binaries (originally unresolved) were identified as PMS stars based on their strong Hα emission and their association with dark clouds. Using the spectral A index, which measures the strength of the CaH band at 697.5nm relative to the nearby continuum as a luminosity class indicator, I showed that the classical T Tauri stars in the sample tend to be close to luminosity class V. Eight out of the 14 pairs could be placed on an H--R diagram. When comparing with theoretical PMS evolutionary tracks the individual components of all pairs appear to be coeval within the observational errors. This result is similar to Hartigan et al. (1994) who found two thirds of the wider pairs with separations from 400 AU to 6000 AU to be coeval. However, unlike Hartigan et al.'s finding for the wider pairs, I find no non-coeval pairs. One of the presumed binaries in our sample (ESO Hα 281) turned out to be a likely chance projection with the ``primary'' showing neither Hα emission nor Li absorption. Finally, using adaptive optics at the ESO 3.6m telescope, diffraction-limited JHK images of the region around the Herbig AeBe star NX Pup were obtained. The close companion (sep. 0.''128) to NX Pup -- originally discovered by HST -- was clearly resolved and its JHK magnitudes were determined. A third object at a separation of 7.''0 from NX Pup was identified as a classical T Tauri star so that NX Pup may in fact form a hierarchical triple system. I discuss the evolutionary status of these stars and derive estimates for their spectral types, luminosities, masses, and ages. My conclusions are that binarity is established very early in stellar evolution, that the orbital parameters of wide binaries (a >= 120AU) remain virtually unchanged during their PMS evolution, and that the components of the wide binaries were formed at the same time --- perhaps either through collisional fragmentation or fragmentation of rotating filaments. (Copies of the thesis (written in German) and related pre-/reprints are available from the author upon request.)

Classifying machinery condition using oil samples and binary logistic regression

NASA Astrophysics Data System (ADS)

Phillips, J.; Cripps, E.; Lau, John W.; Hodkiewicz, M. R.

2015-08-01

The era of big data has resulted in an explosion of condition monitoring information. The result is an increasing motivation to automate the costly and time consuming human elements involved in the classification of machine health. When working with industry it is important to build an understanding and hence some trust in the classification scheme for those who use the analysis to initiate maintenance tasks. Typically "black box" approaches such as artificial neural networks (ANN) and support vector machines (SVM) can be difficult to provide ease of interpretability. In contrast, this paper argues that logistic regression offers easy interpretability to industry experts, providing insight to the drivers of the human classification process and to the ramifications of potential misclassification. Of course, accuracy is of foremost importance in any automated classification scheme, so we also provide a comparative study based on predictive performance of logistic regression, ANN and SVM. A real world oil analysis data set from engines on mining trucks is presented and using cross-validation we demonstrate that logistic regression out-performs the ANN and SVM approaches in terms of prediction for healthy/not healthy engines.

A hybrid binary particle swarm optimization for large capacitated multi item multi level lot sizing (CMIMLLS) problem

NASA Astrophysics Data System (ADS)

Mishra, S. K.; Sahithi, V. V. D.; Rao, C. S. P.

2016-09-01

The lot sizing problem deals with finding optimal order quantities which minimizes the ordering and holding cost of product mix. when multiple items at multiple levels with all capacity restrictions are considered, the lot sizing problem become NP hard. Many heuristics were developed in the past have inevitably failed due to size, computational complexity and time. However the authors were successful in the development of PSO based technique namely iterative improvement binary particles swarm technique to address very large capacitated multi-item multi level lot sizing (CMIMLLS) problem. First binary particle Swarm Optimization algorithm is used to find a solution in a reasonable time and iterative improvement local search mechanism is employed to improvise the solution obtained by BPSO algorithm. This hybrid mechanism of using local search on the global solution is found to improve the quality of solutions with respect to time thus IIBPSO method is found best and show excellent results.

Multiple mating and its relationship to brood size in pregnant fishes versus pregnant mammals and other viviparous vertebrates

PubMed Central

Avise, John C.; Liu, Jin-Xian

2011-01-01

We summarize the literature on rates of multiple paternity and sire numbers per clutch in viviparous fishes vs. mammals, two vertebrate groups in which pregnancy is common but entails very different numbers of embryos (for species surveyed, piscine broods averaged >10-fold larger than mammalian litters). As deduced from genetic parentage analyses, multiple mating by the pregnant sex proved to be common in assayed species but averaged significantly higher in fish than mammals. However, within either of these groups we found no significant correlations between brood size and genetically deduced incidence of multiple mating by females. Overall, these findings offer little support for the hypothesis that clutch size in pregnant species predicts the outcome of selection for multiple mating by brooders. Instead, whatever factors promote multiple mating by members of the gestating sex seem to do so in surprisingly similar ways in live-bearing vertebrates otherwise as different as fish and mammals. Similar conclusions emerged when we extended the survey to viviparous amphibians and reptiles. One notion consistent with these empirical observations is that although several fitness benefits probably accrue from multiple mating, logistical constraints on mate-encounter rates routinely truncate multiple mating far below levels that otherwise could be accommodated, especially in species with larger broods. We develop this concept into a “logistical constraint hypothesis” that may help to explain these mating outcomes in viviparous vertebrates. Under the logistical constraint hypothesis, propensities for multiple mating in each species register a balance between near-universal fitness benefits from multiple mating and species-idiosyncratic logistical limits on polygamy. PMID:21482777

On the Occurrence of Wide Binaries in the Local Disk and Halo Populations

NASA Astrophysics Data System (ADS)

Hartman, Zachary; Lepine, Sebastien

2018-01-01

We present results from our search for wide binaries in the SUPERBLINK+GAIA all-sky catalog of 2.8 million high proper motion stars (μ>40 mas/yr). Through a Bayesian analysis of common proper motion pairs, we have identified highly probable wide binary/multiple systems based on statistics of their proper motion differences and angular separations. Using a reduced proper motion diagram, we determine whether these wide are part of the young disk, old disk, or Galactic halo population. We examine the relative occurrence rate for very wide companions in these respective populations. All groups are found to contain a significant number of wide binary systems, with about 1 percent of the stars in each group having pairs with separations >1,000 AU.

DISTINGUISHING COMPACT BINARY POPULATION SYNTHESIS MODELS USING GRAVITATIONAL WAVE OBSERVATIONS OF COALESCING BINARY BLACK HOLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stevenson, Simon; Ohme, Frank; Fairhurst, Stephen, E-mail: simon.stevenson@ligo.org

2015-09-01

The coalescence of compact binaries containing neutron stars or black holes is one of the most promising signals for advanced ground-based laser interferometer gravitational-wave (GW) detectors, with the first direct detections expected over the next few years. The rate of binary coalescences and the distribution of component masses is highly uncertain, and population synthesis models predict a wide range of plausible values. Poorly constrained parameters in population synthesis models correspond to poorly understood astrophysics at various stages in the evolution of massive binary stars, the progenitors of binary neutron star and binary black hole systems. These include effects such asmore » supernova kick velocities, parameters governing the energetics of common envelope evolution and the strength of stellar winds. Observing multiple binary black hole systems through GWs will allow us to infer details of the astrophysical mechanisms that lead to their formation. Here we simulate GW observations from a series of population synthesis models including the effects of known selection biases, measurement errors and cosmology. We compare the predictions arising from different models and show that we will be able to distinguish between them with observations (or the lack of them) from the early runs of the advanced LIGO and Virgo detectors. This will allow us to narrow down the large parameter space for binary evolution models.« less

Evolutionary Pathways for Asteroid Satellites

NASA Astrophysics Data System (ADS)

Jacobson, Seth Andrew

2015-08-01

The YORP-induced rotational fission hypothesis is a proposed mechanism for the creation of small asteroid binaries, which make up approximately 1/6-th of the near-Earth asteroid and small Main Belt asteroid populations. The YORP effect is a radiative torque that rotationally accelerates asteroids on timescales of thousands to millions of years. As asteroids rotationally accelerate, centrifugal accelerations on material within the body can match gravitational accelerations holding that material in place. When this occurs, that material goes into orbit. Once in orbit that material coalesces into a companion that undergoes continued dynamical evolution.Observations with radar, photometric and direct imaging techniques reveal a diverse array of small asteroid satellites. These systems can be sorted into a number of morphologies according to size, multiplicity of members, dynamical orbit and spin states, and member shapes. For instance, singly synchronous binaries have short separation distances between the two members, rapidly rotating oblate primary members, and tidally locked prolate secondary members. Other confirmed binary morphologies include doubly synchronous, tight asynchronous and wide asynchronous binaries. Related to these binary morphologies are unbound paired asteroid systems and bi-lobate contact binaries.A critical test for the YORP-induced rotational fission hypothesis is whether the binary asteroids produced evolve to the observed binary and related systems. In this talk I will review how this evolution is believed to occur according to gravitational dynamics, mutual body tides and the binary YORP effect.

The multiplicity of T Tauri stars in the star forming regions Taurus-Auriga and Ophiuchus-Scorpius: A 2.2 micron speckle imaging survey

NASA Technical Reports Server (NTRS)

Ghez, A. M.; Neugebauer, G.; Matthews, K.

1993-01-01

We present the results of a magnitude limited (K less than = 8.5 mag) speckle imaging survey of 69 T Tauri stars in the star forming regions Taurus-Auriga and Ophiuchus-Scorpius. Thirty-three companion stars were found with separations ranging from 0.07 sec to 2.5 sec, nine are new detections. This survey reveals a distinction between the classical T Tauri stars (CTTS) and the weak-lined T Tauri stars (WTTS) based on the binary star frequency as a function of separation: the WTTS binary star distribution is enhanced at the closer separations (less than 50 AU) relative to the CTTS binary star distribution. We suggest that the nearby companion stars shorten the accretion time scale in multiple star systems, thereby accounting for the presence of WTTS that are coeval with many CTTS. The binary star frequency in the projected linear separation range 16 to 252 AU for T Tauri stars (60 (+/- 17)%) is a factor of 4 greater than that of the solar-type main-sequence stars (16(+/- 3)%). Given the limited separation range of this survey, the rate at which binaries are detected suggests that most, if not all, T Tauri stars have companions. We propose that the observed overabundance of companions of T Tauri stars is an evolutionary effect, in which triple and higher order T Tauri stars are disrupted by close encounters with another star or system of stars.

Cost-Sensitive Local Binary Feature Learning for Facial Age Estimation.

PubMed

Lu, Jiwen; Liong, Venice Erin; Zhou, Jie

2015-12-01

In this paper, we propose a cost-sensitive local binary feature learning (CS-LBFL) method for facial age estimation. Unlike the conventional facial age estimation methods that employ hand-crafted descriptors or holistically learned descriptors for feature representation, our CS-LBFL method learns discriminative local features directly from raw pixels for face representation. Motivated by the fact that facial age estimation is a cost-sensitive computer vision problem and local binary features are more robust to illumination and expression variations than holistic features, we learn a series of hashing functions to project raw pixel values extracted from face patches into low-dimensional binary codes, where binary codes with similar chronological ages are projected as close as possible, and those with dissimilar chronological ages are projected as far as possible. Then, we pool and encode these local binary codes within each face image as a real-valued histogram feature for face representation. Moreover, we propose a cost-sensitive local binary multi-feature learning method to jointly learn multiple sets of hashing functions using face patches extracted from different scales to exploit complementary information. Our methods achieve competitive performance on four widely used face aging data sets.

Self-Supervised Video Hashing With Hierarchical Binary Auto-Encoder.

PubMed

Song, Jingkuan; Zhang, Hanwang; Li, Xiangpeng; Gao, Lianli; Wang, Meng; Hong, Richang

2018-07-01

Existing video hash functions are built on three isolated stages: frame pooling, relaxed learning, and binarization, which have not adequately explored the temporal order of video frames in a joint binary optimization model, resulting in severe information loss. In this paper, we propose a novel unsupervised video hashing framework dubbed self-supervised video hashing (SSVH), which is able to capture the temporal nature of videos in an end-to-end learning to hash fashion. We specifically address two central problems: 1) how to design an encoder-decoder architecture to generate binary codes for videos and 2) how to equip the binary codes with the ability of accurate video retrieval. We design a hierarchical binary auto-encoder to model the temporal dependencies in videos with multiple granularities, and embed the videos into binary codes with less computations than the stacked architecture. Then, we encourage the binary codes to simultaneously reconstruct the visual content and neighborhood structure of the videos. Experiments on two real-world data sets show that our SSVH method can significantly outperform the state-of-the-art methods and achieve the current best performance on the task of unsupervised video retrieval.

How do binary separations depend on cloud initial conditions?

NASA Astrophysics Data System (ADS)

Sterzik, M. F.; Durisen, R. H.; Zinnecker, H.

2003-11-01

We explore the consequences of a star formation scenario in which the isothermal collapse of a rotating, star-forming core is followed by prompt fragmentation into a cluster containing a small number (N <~ 10) of protostars and/or substellar objects. The subsequent evolution of the cluster is assumed to be dominated by dynamical interactions among cluster members, and this establishes the final properties of the binary and multiple systems. The characteristic scale of the fragmenting core is determined by the cloud initial conditions (such as temperature, angular momentum and mass), and we are able to relate the separation distributions of the final binary population to the properties of the star-forming core. Because the fragmentation scale immediately after the isothermal collapse is typically a factor of 3-10 too large, we conjecture that fragmentation into small clusters followed by dynamical evolution is required to account for the observed binary separation distributions. Differences in the environmental properties of the cores are expected to imprint differences on the characteristic dimensions of the binary systems they form. Recent observations of hierarchical systems, differences in binary characteristics among star forming regions and systematic variations in binary properties with primary mass can be interpreted in the context of this scenario.

Self-Supervised Video Hashing With Hierarchical Binary Auto-Encoder

NASA Astrophysics Data System (ADS)

Song, Jingkuan; Zhang, Hanwang; Li, Xiangpeng; Gao, Lianli; Wang, Meng; Hong, Richang

2018-07-01

Existing video hash functions are built on three isolated stages: frame pooling, relaxed learning, and binarization, which have not adequately explored the temporal order of video frames in a joint binary optimization model, resulting in severe information loss. In this paper, we propose a novel unsupervised video hashing framework dubbed Self-Supervised Video Hashing (SSVH), that is able to capture the temporal nature of videos in an end-to-end learning-to-hash fashion. We specifically address two central problems: 1) how to design an encoder-decoder architecture to generate binary codes for videos; and 2) how to equip the binary codes with the ability of accurate video retrieval. We design a hierarchical binary autoencoder to model the temporal dependencies in videos with multiple granularities, and embed the videos into binary codes with less computations than the stacked architecture. Then, we encourage the binary codes to simultaneously reconstruct the visual content and neighborhood structure of the videos. Experiments on two real-world datasets (FCVID and YFCC) show that our SSVH method can significantly outperform the state-of-the-art methods and achieve the currently best performance on the task of unsupervised video retrieval.

Binary Logistic Regression Analysis in Assessment and Identifying Factors That Influence Students' Academic Achievement: The Case of College of Natural and Computational Science, Wolaita Sodo University, Ethiopia

ERIC Educational Resources Information Center

Zewude, Bereket Tessema; Ashine, Kidus Meskele

2016-01-01

An attempt has been made to assess and identify the major variables that influence student academic achievement at college of natural and computational science of Wolaita Sodo University in Ethiopia. Study time, peer influence, securing first choice of department, arranging study time outside class, amount of money received from family, good life…

The Impact of Additional Weekdays of Active Commuting to School on Children Achieving a Criterion of 300+ Minutes of Moderate-to-Vigorous Physical Activity

ERIC Educational Resources Information Center

Daly-Smith, Andy J. W.; McKenna, Jim; Radley, Duncan; Long, Jonathan

2011-01-01

Objective: To investigate the value of additional days of active commuting for meeting a criterion of 300+ minutes of moderate-to-vigorous physical activity (MVPA; 60+ mins/day x 5) during the school week. Methods: Based on seven-day diaries supported by teachers, binary logistic regression analyses were used to predict achievement of MVPA…

Prevalence and determinants of cardiovascular disease risk factors among the residents of urban community housing projects in Malaysia.

PubMed

Amiri, Mohammadreza; Majid, Hazreen Abdul; Hairi, FarizahMohd; Thangiah, Nithiah; Bulgiba, Awang; Su, Tin Tin

2014-01-01

The objectives are to assess the prevalence and determinants of cardiovascular disease (CVD) risk factors among the residents of Community Housing Projects in metropolitan Kuala Lumpur, Malaysia. By using simple random sampling, we selected and surveyed 833 households which comprised of 3,722 individuals. Out of the 2,360 adults, 50.5% participated in blood sampling and anthropometric measurement sessions. Uni and bivariate data analysis and multivariate binary logistic regression were applied to identify demographic and socioeconomic determinants of the existence of having at least one CVD risk factor. As a Result, while obesity (54.8%), hypercholesterolemia (51.5%), and hypertension (39.3%) were the most common CVD risk factors among the low-income respondents, smoking (16.3%), diabetes mellitus (7.8%) and alcohol consumption (1.4%) were the least prevalent. Finally, the results from the multivariate binary logistic model illustrated that compared to the Malays, the Indians were 41% less likely to have at least one of the CVD risk factors (OR = 0.59; 95% CI: 0.37 - 0.93). In Conclusion, the low-income individuals were at higher risk of developing CVDs. Prospective policies addressing preventive actions and increased awareness focusing on low-income communities are highly recommended and to consider age, gender, ethnic backgrounds, and occupation classes.

Social Impact of Stigma Regarding Tuberculosis Hindering Adherence to Treatment: A Cross Sectional Study Involving Tuberculosis Patients in Rajshahi City, Bangladesh.

PubMed

Chowdhury, Md Rocky Khan; Rahman, Md Shafiur; Mondal, Md Nazrul Islam; Sayem, Abu; Billah, Baki

2015-01-01

Stigma, considered a social disease, is more apparent in developing societies which are driven by various social affairs, and influences adherence to treatment. The aim of the present study was to examine levels of social stigma related to tuberculosis (TB) in sociodemographic context and identify the effects of sociodemographic factors on stigma. The study sample consisted of 372 TB patients. Data were collected using stratified sampling with simple random sampling techniques. T tests, chi-square tests, and binary logistic regression analysis were performed to examine correlations between stigma and sociodemographic variables. Approximately 85.9% of patients had experienced stigma. The most frequent indicator of the stigma experienced by patients involved problems taking part in social programs (79.5%). Mean levels of stigma were significantly higher in women (55.5%), illiterate individuals (60.8%), and villagers (60.8%) relative to those of other groups. Chi-square tests revealed that education, monthly family income, and type of patient (pulmonary and extrapulmonary) were significantly associated with stigma. Binary logistic regression analysis demonstrated that stigma was influenced by sex, education, and type of patient. Stigma is one of the most important barriers to treatment adherence. Therefore, in interventions that aim to reduce stigma, strong collaboration between various institutions is essential.

A cross-sectional assessment of health-related quality of life in Chinese patients with chronic hepatitis c virus infection with EQ-5D.

PubMed

Huang, Rui; Rao, Huiying; Shang, Jia; Chen, Hong; Li, Jun; Xie, Qing; Gao, Zhiliang; Wang, Lei; Wei, Jia; Jiang, Jianning; Sun, Jian; Jiang, Jiaji; Wei, Lai

2018-06-15

Hepatitis C virus (HCV) infection is one of the most common liver infections, with a decrement in HRQoL of HCV patients. This study aims to assess Health-related quality of life (HRQoL) in Chinese patients with chronic HCV infection, and to identify significant predictors of the HRQoL in these patients of China. In this cross-sectional observational study, treatment-naïve Han ethnic adults with chronic HCV infection were enrolled. Adopting European Quality of Life scale (EQ-5D) and EuroQOL visual analogue scale (EQ-VAS) were used to qualify HRQoL. Results were reported in descriptive analyses to describe sociodemographic and clinical characteristics. Multiple linear regression analysis was applied to investigate the associations of these variables with HRQoL. Binary logistic regression analysis was performed to identify associations of these variables with HRQoL by dimensions of EQ-5D. Nine hundred ninety-seven patients were enrolled in the study [median age 46.0 (37.0, 56.0) years; male 54.8%]. Mean EQ-5D index and EQ-VAS score were 0.780 ± 0.083 and 77.2 ± 14.8. Multiple Linear regression analysis showed that income (< 2000 RMB, β = - 0.134; 2000-4999 RMB, β = - 0.085), moderate or severe symptoms of discomfort (more than one symptoms, β = - 0.090), disease profile (cirrhosis, β = - 0.114), hyperlipidemia (β = - 0.065) and depression (β = - 0.065) were independently associated with EQ-5D index. Residence (the west, β = 0.087), income (< 2000 RMB, β = - 0.129; 2000-4999 RMB, β = - 0.052), moderate or severe symptoms of discomfort (more than one symptoms, β = - 0.091), disease profile and depression (β = - 0.316) were the influencing factors on EQ-VAS. Binary logistic regression indicated that disease profile and clinical depression were the major influencing factors on all five dimensions of EQ-5D. In this cross-sectional assessment of HCV patients in China, we indicated HRQoL of Chinese HCV patients. Significant negative associations between HRQoL and sociodemographic and clinical factors such as moderate or severe symptoms of discomfort, disease profile and depression emerged. We have to focus on optimally managing care of HCV patients and improving their HRQoL. ClinicalTrials.gov identifier NCT01293279. Date of registration: February 10, 2011.

The Evolution of the Multiplicity of Embedded Protostars. II. Binary Separation Distribution and Analysis

NASA Astrophysics Data System (ADS)

Connelley, Michael S.; Reipurth, Bo; Tokunaga, Alan T.

2008-06-01

We present the Class I protostellar binary separation distribution based on the data tabulated in a companion paper. We verify the excess of Class I binary stars over solar-type main-sequence stars in the separation range from 500 AU to 4500 AU. Although our sources are in nearby star-forming regions distributed across the entire sky (including Orion), none of our objects are in a high stellar density environment. A log-normal function, used by previous authors to fit the main-sequence and T Tauri binary separation distributions, poorly fits our data, and we determine that a log-uniform function is a better fit. Our observations show that the binary separation distribution changes significantly during the Class I phase, and that the binary frequency at separations greater than 1000 AU declines steadily with respect to spectral index. Despite these changes, the binary frequency remains constant until the end of the Class I phase, when it drops sharply. We propose a scenario to account for the changes in the Class I binary separation distribution. This scenario postulates that a large number of companions with a separation greater than ~1000 AU were ejected during the Class 0 phase, but remain gravitationally bound due to the significant mass of the Class I envelope. As the envelope dissipates, these companions become unbound and the binary frequency at wide separations declines. Circumstellar and circumbinary disks are expected to play an important role in the orbital evolution at closer separations. This scenario predicts that a large number of Class 0 objects should be non-hierarchical multiple systems, and that many Class I young stellar objects (YSOs) with a widely separated companion should also have a very close companion. We also find that Class I protostars are not dynamically pristine, but have experienced dynamical evolution before they are visible as Class I objects. Our analysis shows that the Class I binary frequency and the binary separation distribution strongly depend on the star-forming environment. The Infrared Telescope Facility is operated by the University of Hawaii under Cooperative Agreement no. NCC 5-538 with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program. The United Kingdom Infrared Telescope is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the U.K. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Dynamics of rotationally fissioned asteroids: Source of observed small asteroid systems

NASA Astrophysics Data System (ADS)

Jacobson, Seth A.; Scheeres, Daniel J.

2011-07-01

We present a model of near-Earth asteroid (NEA) rotational fission and ensuing dynamics that describes the creation of synchronous binaries and all other observed NEA systems including: doubly synchronous binaries, high- e binaries, ternary systems, and contact binaries. Our model only presupposes the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, "rubble pile" asteroid geophysics, and gravitational interactions. The YORP effect torques a "rubble pile" asteroid until the asteroid reaches its fission spin limit and the components enter orbit about each other (Scheeres, D.J. [2007]. Icarus 189, 370-385). Non-spherical gravitational potentials couple the spin states to the orbit state and chaotically drive the system towards the observed asteroid classes along two evolutionary tracks primarily distinguished by mass ratio. Related to this is a new binary process termed secondary fission - the secondary asteroid of the binary system is rotationally accelerated via gravitational torques until it fissions, thus creating a chaotic ternary system. The initially chaotic binary can be stabilized to create a synchronous binary by components of the fissioned secondary asteroid impacting the primary asteroid, solar gravitational perturbations, and mutual body tides. These results emphasize the importance of the initial component size distribution and configuration within the parent asteroid. NEAs may go through multiple binary cycles and many YORP-induced rotational fissions during their approximately 10 Myr lifetime in the inner Solar System. Rotational fission and the ensuing dynamics are responsible for all NEA systems including the most commonly observed synchronous binaries.

Constrained binary classification using ensemble learning: an application to cost-efficient targeted PrEP strategies.

PubMed

Zheng, Wenjing; Balzer, Laura; van der Laan, Mark; Petersen, Maya

2018-01-30

Binary classification problems are ubiquitous in health and social sciences. In many cases, one wishes to balance two competing optimality considerations for a binary classifier. For instance, in resource-limited settings, an human immunodeficiency virus prevention program based on offering pre-exposure prophylaxis (PrEP) to select high-risk individuals must balance the sensitivity of the binary classifier in detecting future seroconverters (and hence offering them PrEP regimens) with the total number of PrEP regimens that is financially and logistically feasible for the program. In this article, we consider a general class of constrained binary classification problems wherein the objective function and the constraint are both monotonic with respect to a threshold. These include the minimization of the rate of positive predictions subject to a minimum sensitivity, the maximization of sensitivity subject to a maximum rate of positive predictions, and the Neyman-Pearson paradigm, which minimizes the type II error subject to an upper bound on the type I error. We propose an ensemble approach to these binary classification problems based on the Super Learner methodology. This approach linearly combines a user-supplied library of scoring algorithms, with combination weights and a discriminating threshold chosen to minimize the constrained optimality criterion. We then illustrate the application of the proposed classifier to develop an individualized PrEP targeting strategy in a resource-limited setting, with the goal of minimizing the number of PrEP offerings while achieving a minimum required sensitivity. This proof of concept data analysis uses baseline data from the ongoing Sustainable East Africa Research in Community Health study. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

NASA's Kepler Mission Discovers Multiple Planets Orbiting Twin Suns (Reporter Pkg)

NASA Image and Video Library

2012-08-28

NASA's Kepler mission has discovered the first transiting circumbinary system -- multiple planets orbiting two suns -- 4,900 light-years from Earth, in the constellation Cygnus, proving that more than one planets can form and survive in orbit around a binary star.

Radial velocities of southern visual multiple stars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokovinin, Andrei; Pribulla, Theodor; Fischer, Debra, E-mail: atokovinin@ctio.noao.edu, E-mail: pribulla@ta3.sk, E-mail: debra.fischer@gmail.com

2015-01-01

High-resolution spectra of visual multiple stars were taken in 2008–2009 to detect or confirm spectroscopic subsystems and to determine their orbits. Radial velocities of 93 late-type stars belonging to visual multiple systems were measured by numerical cross-correlation. We provide the individual velocities, the width, and the amplitude of the Gaussians that approximate the correlations. The new information on the multiple systems resulting from these data is discussed. We discovered double-lined binaries in HD 41742B, HD 56593C, and HD 122613AB, confirmed several other known subsystems, and constrained the existence of subsystems in some visual binaries where both components turned out tomore » have similar velocities. The orbits of double-lined subsystems with periods of 148 and 13 days are computed for HD 104471 Aa,Ab and HD 210349 Aa,Ab, respectively. We estimate individual magnitudes and masses of the components in these triple systems and update the outer orbit of HD 104471 AB.« less

[Application of SAS macro to evaluated multiplicative and additive interaction in logistic and Cox regression in clinical practices].

PubMed

Nie, Z Q; Ou, Y Q; Zhuang, J; Qu, Y J; Mai, J Z; Chen, J M; Liu, X Q

2016-05-01

Conditional logistic regression analysis and unconditional logistic regression analysis are commonly used in case control study, but Cox proportional hazard model is often used in survival data analysis. Most literature only refer to main effect model, however, generalized linear model differs from general linear model, and the interaction was composed of multiplicative interaction and additive interaction. The former is only statistical significant, but the latter has biological significance. In this paper, macros was written by using SAS 9.4 and the contrast ratio, attributable proportion due to interaction and synergy index were calculated while calculating the items of logistic and Cox regression interactions, and the confidence intervals of Wald, delta and profile likelihood were used to evaluate additive interaction for the reference in big data analysis in clinical epidemiology and in analysis of genetic multiplicative and additive interactions.

Formation of Kuiper-belt binaries through multiple chaotic scattering encounters with low-mass intruders

NASA Astrophysics Data System (ADS)

Astakhov, Sergey A.; Lee, Ernestine A.; Farrelly, David

2005-06-01

The discovery that many trans-Neptunian objects exist in pairs, or binaries, is proving invaluable for shedding light on the formation, evolution and structure of the outer Solar system. Based on recent systematic searches it has been estimated that up to 10 per cent of Kuiper-belt objects might be binaries. However, all examples discovered to date are unusual, as compared with near-Earth and main-belt asteroid binaries, for their mass ratios of the order of unity and their large, eccentric orbits. In this article we propose a common dynamical origin for these compositional and orbital properties based on four-body simulations in the Hill approximation. Our calculations suggest that binaries are produced through the following chain of events. Initially, long-lived quasi-bound binaries form by two bodies getting entangled in thin layers of dynamical chaos produced by solar tides within the Hill sphere. Next, energy transfer through gravitational scattering with a low-mass intruder nudges the binary into a nearby non-chaotic, stable zone of phase space. Finally, the binary hardens (loses energy) through a series of relatively gentle gravitational scattering encounters with further intruders. This produces binary orbits that are well fitted by Kepler ellipses. Dynamically, the overall process is strongly favoured if the original quasi-bound binary contains comparable masses. We propose a simplified model of chaotic scattering to explain these results. Our findings suggest that the observed preference for roughly equal-mass ratio binaries is probably a real effect; that is, it is not primarily due to an observational bias for widely separated, comparably bright objects. Nevertheless, we predict that a sizeable population of very unequal-mass Kuiper-belt binaries is probably awaiting discovery.

Equilibrium points and associated periodic orbits in the gravity of binary asteroid systems: (66391) 1999 KW4 as an example

NASA Astrophysics Data System (ADS)

Shi, Yu; Wang, Yue; Xu, Shijie

2018-04-01

The motion of a massless particle in the gravity of a binary asteroid system, referred as the restricted full three-body problem (RF3BP), is fundamental, not only for the evolution of the binary system, but also for the design of relevant space missions. In this paper, equilibrium points and associated periodic orbit families in the gravity of a binary system are investigated, with the binary (66391) 1999 KW4 as an example. The polyhedron shape model is used to describe irregular shapes and corresponding gravity fields of the primary and secondary of (66391) 1999 KW4, which is more accurate than the ellipsoid shape model in previous studies and provides a high-fidelity representation of the gravitational environment. Both of the synchronous and non-synchronous states of the binary system are considered. For the synchronous binary system, the equilibrium points and their stability are determined, and periodic orbit families emanating from each equilibrium point are generated by using the shooting (multiple shooting) method and the homotopy method, where the homotopy function connects the circular restricted three-body problem and RF3BP. In the non-synchronous binary system, trajectories of equivalent equilibrium points are calculated, and the associated periodic orbits are obtained by using the homotopy method, where the homotopy function connects the synchronous and non-synchronous systems. Although only the binary (66391) 1999 KW4 is considered, our methods will also be well applicable to other binary systems with polyhedron shape data. Our results on equilibrium points and associated periodic orbits provide general insights into the dynamical environment and orbital behaviors in proximity of small binary asteroids and enable the trajectory design and mission operations in future binary system explorations.

Logistic random effects regression models: a comparison of statistical packages for binary and ordinal outcomes.

PubMed

Li, Baoyue; Lingsma, Hester F; Steyerberg, Ewout W; Lesaffre, Emmanuel

2011-05-23

Logistic random effects models are a popular tool to analyze multilevel also called hierarchical data with a binary or ordinal outcome. Here, we aim to compare different statistical software implementations of these models. We used individual patient data from 8509 patients in 231 centers with moderate and severe Traumatic Brain Injury (TBI) enrolled in eight Randomized Controlled Trials (RCTs) and three observational studies. We fitted logistic random effects regression models with the 5-point Glasgow Outcome Scale (GOS) as outcome, both dichotomized as well as ordinal, with center and/or trial as random effects, and as covariates age, motor score, pupil reactivity or trial. We then compared the implementations of frequentist and Bayesian methods to estimate the fixed and random effects. Frequentist approaches included R (lme4), Stata (GLLAMM), SAS (GLIMMIX and NLMIXED), MLwiN ([R]IGLS) and MIXOR, Bayesian approaches included WinBUGS, MLwiN (MCMC), R package MCMCglmm and SAS experimental procedure MCMC.Three data sets (the full data set and two sub-datasets) were analysed using basically two logistic random effects models with either one random effect for the center or two random effects for center and trial. For the ordinal outcome in the full data set also a proportional odds model with a random center effect was fitted. The packages gave similar parameter estimates for both the fixed and random effects and for the binary (and ordinal) models for the main study and when based on a relatively large number of level-1 (patient level) data compared to the number of level-2 (hospital level) data. However, when based on relatively sparse data set, i.e. when the numbers of level-1 and level-2 data units were about the same, the frequentist and Bayesian approaches showed somewhat different results. The software implementations differ considerably in flexibility, computation time, and usability. There are also differences in the availability of additional tools for model evaluation, such as diagnostic plots. The experimental SAS (version 9.2) procedure MCMC appeared to be inefficient. On relatively large data sets, the different software implementations of logistic random effects regression models produced similar results. Thus, for a large data set there seems to be no explicit preference (of course if there is no preference from a philosophical point of view) for either a frequentist or Bayesian approach (if based on vague priors). The choice for a particular implementation may largely depend on the desired flexibility, and the usability of the package. For small data sets the random effects variances are difficult to estimate. In the frequentist approaches the MLE of this variance was often estimated zero with a standard error that is either zero or could not be determined, while for Bayesian methods the estimates could depend on the chosen "non-informative" prior of the variance parameter. The starting value for the variance parameter may be also critical for the convergence of the Markov chain.

Computing all hybridization networks for multiple binary phylogenetic input trees.

PubMed

Albrecht, Benjamin

2015-07-30

The computation of phylogenetic trees on the same set of species that are based on different orthologous genes can lead to incongruent trees. One possible explanation for this behavior are interspecific hybridization events recombining genes of different species. An important approach to analyze such events is the computation of hybridization networks. This work presents the first algorithm computing the hybridization number as well as a set of representative hybridization networks for multiple binary phylogenetic input trees on the same set of taxa. To improve its practical runtime, we show how this algorithm can be parallelized. Moreover, we demonstrate the efficiency of the software Hybroscale, containing an implementation of our algorithm, by comparing it to PIRNv2.0, which is so far the best available software computing the exact hybridization number for multiple binary phylogenetic trees on the same set of taxa. The algorithm is part of the software Hybroscale, which was developed specifically for the investigation of hybridization networks including their computation and visualization. Hybroscale is freely available(1) and runs on all three major operating systems. Our simulation study indicates that our approach is on average 100 times faster than PIRNv2.0. Moreover, we show how Hybroscale improves the interpretation of the reported hybridization networks by adding certain features to its graphical representation.

Multiple logistic regression model of signalling practices of drivers on urban highways

NASA Astrophysics Data System (ADS)

Puan, Othman Che; Ibrahim, Muttaka Na'iya; Zakaria, Rozana

2015-05-01

Giving signal is a way of informing other road users, especially to the conflicting drivers, the intention of a driver to change his/her movement course. Other users are exposed to hazard situation and risks of accident if the driver who changes his/her course failed to give signal as required. This paper describes the application of logistic regression model for the analysis of driver's signalling practices on multilane highways based on possible factors affecting driver's decision such as driver's gender, vehicle's type, vehicle's speed and traffic flow intensity. Data pertaining to the analysis of such factors were collected manually. More than 2000 drivers who have performed a lane changing manoeuvre while driving on two sections of multilane highways were observed. Finding from the study shows that relatively a large proportion of drivers failed to give any signals when changing lane. The result of the analysis indicates that although the proportion of the drivers who failed to provide signal prior to lane changing manoeuvre is high, the degree of compliances of the female drivers is better than the male drivers. A binary logistic model was developed to represent the probability of a driver to provide signal indication prior to lane changing manoeuvre. The model indicates that driver's gender, type of vehicle's driven, speed of vehicle and traffic volume influence the driver's decision to provide a signal indication prior to a lane changing manoeuvre on a multilane urban highway. In terms of types of vehicles driven, about 97% of motorcyclists failed to comply with the signal indication requirement. The proportion of non-compliance drivers under stable traffic flow conditions is much higher than when the flow is relatively heavy. This is consistent with the data which indicates a high degree of non-compliances when the average speed of the traffic stream is relatively high.

Influence of landscape-scale factors in limiting brook trout populations in Pennsylvania streams

USGS Publications Warehouse

Kocovsky, P.M.; Carline, R.F.

2006-01-01

Landscapes influence the capacity of streams to produce trout through their effect on water chemistry and other factors at the reach scale. Trout abundance also fluctuates over time; thus, to thoroughly understand how spatial factors at landscape scales affect trout populations, one must assess the changes in populations over time to provide a context for interpreting the importance of spatial factors. We used data from the Pennsylvania Fish and Boat Commission's fisheries management database to investigate spatial factors that affect the capacity of streams to support brook trout Salvelinus fontinalis and to provide models useful for their management. We assessed the relative importance of spatial and temporal variation by calculating variance components and comparing relative standard errors for spatial and temporal variation. We used binary logistic regression to predict the presence of harvestable-length brook trout and multiple linear regression to assess the mechanistic links between landscapes and trout populations and to predict population density. The variance in trout density among streams was equal to or greater than the temporal variation for several streams, indicating that differences among sites affect population density. Logistic regression models correctly predicted the absence of harvestable-length brook trout in 60% of validation samples. The r 2-value for the linear regression model predicting density was 0.3, indicating low predictive ability. Both logistic and linear regression models supported buffering capacity against acid episodes as an important mechanistic link between landscapes and trout populations. Although our models fail to predict trout densities precisely, their success at elucidating the mechanistic links between landscapes and trout populations, in concert with the importance of spatial variation, increases our understanding of factors affecting brook trout abundance and will help managers and private groups to protect and enhance populations of wild brook trout. ?? Copyright by the American Fisheries Society 2006.

Explaining Match Outcome During The Men’s Basketball Tournament at The Olympic Games

PubMed Central

Leicht, Anthony S.; Gómez, Miguel A.; Woods, Carl T.

2017-01-01

In preparation for the Olympics, there is a limited opportunity for coaches and athletes to interact regularly with team performance indicators providing important guidance to coaches for enhanced match success at the elite level. This study examined the relationship between match outcome and team performance indicators during men’s basketball tournaments at the Olympic Games. Twelve team performance indicators were collated from all men’s teams and matches during the basketball tournament of the 2004-2016 Olympic Games (n = 156). Linear and non-linear analyses examined the relationship between match outcome and team performance indicator characteristics; namely, binary logistic regression and a conditional interference (CI) classification tree. The most parsimonious logistic regression model retained ‘assists’, ‘defensive rebounds’, ‘field-goal percentage’, ‘fouls’, ‘fouls against’, ‘steals’ and ‘turnovers’ (delta AIC <0.01; Akaike weight = 0.28) with a classification accuracy of 85.5%. Conversely, four performance indicators were retained with the CI classification tree with an average classification accuracy of 81.4%. However, it was the combination of ‘field-goal percentage’ and ‘defensive rebounds’ that provided the greatest probability of winning (93.2%). Match outcome during the men’s basketball tournaments at the Olympic Games was identified by a unique combination of performance indicators. Despite the average model accuracy being marginally higher for the logistic regression analysis, the CI classification tree offered a greater practical utility for coaches through its resolution of non-linear phenomena to guide team success. Key points A unique combination of team performance indicators explained 93.2% of winning observations in men’s basketball at the Olympics. Monitoring of these team performance indicators may provide coaches with the capability to devise multiple game plans or strategies to enhance their likelihood of winning. Incorporation of machine learning techniques with team performance indicators may provide a valuable and strategic approach to explain patterns within multivariate datasets in sport science. PMID:29238245

Forecast Modelling via Variations in Binary Image-Encoded Information Exploited by Deep Learning Neural Networks.

PubMed

Liu, Da; Xu, Ming; Niu, Dongxiao; Wang, Shoukai; Liang, Sai

2016-01-01

Traditional forecasting models fit a function approximation from dependent invariables to independent variables. However, they usually get into trouble when date are presented in various formats, such as text, voice and image. This study proposes a novel image-encoded forecasting method that input and output binary digital two-dimensional (2D) images are transformed from decimal data. Omitting any data analysis or cleansing steps for simplicity, all raw variables were selected and converted to binary digital images as the input of a deep learning model, convolutional neural network (CNN). Using shared weights, pooling and multiple-layer back-propagation techniques, the CNN was adopted to locate the nexus among variations in local binary digital images. Due to the computing capability that was originally developed for binary digital bitmap manipulation, this model has significant potential for forecasting with vast volume of data. The model was validated by a power loads predicting dataset from the Global Energy Forecasting Competition 2012.

Multiclass Reduced-Set Support Vector Machines

NASA Technical Reports Server (NTRS)

Tang, Benyang; Mazzoni, Dominic

2006-01-01

There are well-established methods for reducing the number of support vectors in a trained binary support vector machine, often with minimal impact on accuracy. We show how reduced-set methods can be applied to multiclass SVMs made up of several binary SVMs, with significantly better results than reducing each binary SVM independently. Our approach is based on Burges' approach that constructs each reduced-set vector as the pre-image of a vector in kernel space, but we extend this by recomputing the SVM weights and bias optimally using the original SVM objective function. This leads to greater accuracy for a binary reduced-set SVM, and also allows vectors to be 'shared' between multiple binary SVMs for greater multiclass accuracy with fewer reduced-set vectors. We also propose computing pre-images using differential evolution, which we have found to be more robust than gradient descent alone. We show experimental results on a variety of problems and find that this new approach is consistently better than previous multiclass reduced-set methods, sometimes with a dramatic difference.

Forecast Modelling via Variations in Binary Image-Encoded Information Exploited by Deep Learning Neural Networks

PubMed Central

Xu, Ming; Niu, Dongxiao; Wang, Shoukai; Liang, Sai

2016-01-01

Traditional forecasting models fit a function approximation from dependent invariables to independent variables. However, they usually get into trouble when date are presented in various formats, such as text, voice and image. This study proposes a novel image-encoded forecasting method that input and output binary digital two-dimensional (2D) images are transformed from decimal data. Omitting any data analysis or cleansing steps for simplicity, all raw variables were selected and converted to binary digital images as the input of a deep learning model, convolutional neural network (CNN). Using shared weights, pooling and multiple-layer back-propagation techniques, the CNN was adopted to locate the nexus among variations in local binary digital images. Due to the computing capability that was originally developed for binary digital bitmap manipulation, this model has significant potential for forecasting with vast volume of data. The model was validated by a power loads predicting dataset from the Global Energy Forecasting Competition 2012. PMID:27281032

(3749) BALAM: A VERY YOUNG MULTIPLE ASTEROID SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vokrouhlicky, David, E-mail: vokrouhl@cesnet.c

2009-11-20

Binaries and multiple systems among small bodies in the solar system have received wide attention over the past decade. This is because their observations provide a wealth of data otherwise inaccessible for single objects. We use numerical integration to prove that the multiple asteroid system (3749) Balam is very young, in contrast to its previously assumed age of 0.5-1 Gyr related to the formation of the Flora family. This work is enabled by a fortuitous discovery of a paired component to (3749) Balam. We first show that the proximity of the (3749) Balam and 2009 BR60 orbits is not amore » statistical fluke of otherwise quasi-uniform distribution. Numerical integrations then strengthen the case and allow us to prove that 2009 BR60 separated from the Balam system less than a million years ago. This is the first time the age of a binary asteroid can be estimated with such accuracy.« less

On Bayesian Rules for Selecting 3PL Binary Items for Criterion-Referenced Interpretations and Creating Booklets for Bookmark Standard Setting.

ERIC Educational Resources Information Center

Huynh, Huynh

By noting that a Rasch or two parameter logistic (2PL) item belongs to the exponential family of random variables and that the probability density function (pdf) of the correct response (X=1) and the incorrect response (X=0) are symmetric with respect to the vertical line at the item location, it is shown that the conjugate prior for ability is…

A combination chaotic system and application in color image encryption

NASA Astrophysics Data System (ADS)

Parvaz, R.; Zarebnia, M.

2018-05-01

In this paper, by using Logistic, Sine and Tent systems we define a combination chaotic system. Some properties of the chaotic system are studied by using figures and numerical results. A color image encryption algorithm is introduced based on new chaotic system. Also this encryption algorithm can be used for gray scale or binary images. The experimental results of the encryption algorithm show that the encryption algorithm is secure and practical.

Use of conservative and surgical foot care in an inception cohort of patients with rheumatoid arthritis

PubMed Central

Keenan, Anne-Maree; Hensor, Elizabeth M. A.; Young, Adam; James, David; Dixey, Josh; Williams, Peter; Prouse, Peter; Gough, Andrew; Helliwell, Philip S.; Redmond, Anthony C.

2011-01-01

Objectives. To describe conservative and surgical foot care in patients with RA in England and explore factors that predict the type of foot care received. Methods. Use of podiatry and type of foot surgery were outcomes recorded in an inception cohort involving nine rheumatology centres that recruited patients with RA between 1986 and 1998 across England. Associations between patient-specific factors and service use were identified using univariate logistic regression analyses. The independence of these associations was then verified through multiple binary logistic regression modelling. Results. Data were collected on 1237 patients with RA [66.9% females, mean (s.d.) age at disease onset = 54.36 (14.18) years, median DAS = 4.09 (1st quartile = 3.04, 3rd quartile = 5.26), median HAQ = 1 (0.50, 1.63)]. Interventions involving the feet in the cohort were low with only 364 (30%) out of 1218 receiving podiatry and 47 (4%) out of 1237 patients having surgery. At baseline, female gender, increasing age at onset, being RF positive and higher DAS scores were each independently associated with increased odds of seeing a podiatrist. Gender, age of onset and baseline DAS were independently associated with the odds of having foot surgery. Conclusions. Despite the known high prevalence of foot pathologies in RA, only one-third of this cohort accessed podiatry. While older females were more likely to access podiatry care and younger patients surgery, the majority of the RA population did not access any foot care. PMID:21504991

Joint and fascial chronic graft-vs-host disease: correlations with clinical and laboratory parameters

PubMed Central

Vukić, Tamara; Smith, Sean Robinson; Ljubas Kelečić, Dina; Desnica, Lana; Prenc, Ema; Pulanić, Dražen; Vrhovac, Radovan; Nemet, Damir; Pavletic, Steven Z.

2016-01-01

Aim To determine if there are correlations between joint and fascial chronic graft-vs-host disease (cGVHD) with clinical findings, laboratory parameters, and measures of functional capacity. Methods 29 patients were diagnosed with cGVHD based on National Institutes of Health (NIH) Consensus Criteria at the University Hospital Centre Zagreb from October 2013 to October 2015. Physical examination, including functional measures such as 2-minute walk test and hand grip strength, as well as laboratory tests were performed. The relationship between these evaluations and the severity of joint and fascial cGVHD was tested by logistical regression analysis. Results 12 of 29 patients (41.3%) had joint and fascial cGVHD diagnosed according to NIH Consensus Criteria. There was a significant positive correlation of joint and fascial cGVHD and skin cGVHD (P < 0.001), serum C3 complement level (P = 0.045), and leukocytes (P = 0.032). There was a significant negative correlation between 2-minute walk test (P = 0.016), percentage of cytotoxic T cells CD3+/CD8+ (P = 0.022), serum albumin (P = 0.047), and Karnofsky score (P < 0.001). Binary logistic regression model found that a significant predictor for joint and fascial cGVHD was cGVHD skin involvement (odds ratio, 7.79; 95 confidence interval 1.87-32.56; P = 0.005). Conclusion Joint and fascial cGVHD manifestations correlated with multiple laboratory measurements, clinical features, and cGVHD skin involvement, which was a significant predictor for joint and fascial cGVHD. PMID:27374828

Extension of the Peters–Belson method to estimate health disparities among multiple groups using logistic regression with survey data

PubMed Central

Li, Y.; Graubard, B. I.; Huang, P.; Gastwirth, J. L.

2015-01-01

Determining the extent of a disparity, if any, between groups of people, for example, race or gender, is of interest in many fields, including public health for medical treatment and prevention of disease. An observed difference in the mean outcome between an advantaged group (AG) and disadvantaged group (DG) can be due to differences in the distribution of relevant covariates. The Peters–Belson (PB) method fits a regression model with covariates to the AG to predict, for each DG member, their outcome measure as if they had been from the AG. The difference between the mean predicted and the mean observed outcomes of DG members is the (unexplained) disparity of interest. We focus on applying the PB method to estimate the disparity based on binary/multinomial/proportional odds logistic regression models using data collected from complex surveys with more than one DG. Estimators of the unexplained disparity, an analytic variance–covariance estimator that is based on the Taylor linearization variance–covariance estimation method, as well as a Wald test for testing a joint null hypothesis of zero for unexplained disparities between two or more minority groups and a majority group, are provided. Simulation studies with data selected from simple random sampling and cluster sampling, as well as the analyses of disparity in body mass index in the National Health and Nutrition Examination Survey 1999–2004, are conducted. Empirical results indicate that the Taylor linearization variance–covariance estimation is accurate and that the proposed Wald test maintains the nominal level. PMID:25382235

Sequence analysis to assess labour market participation following vocational rehabilitation: an observational study among patients sick-listed with low back pain from a randomised clinical trial in Denmark

PubMed Central

Lindholdt, Louise; Labriola, Merete; Nielsen, Claus Vinther; Horsbøl, Trine Allerslev; Lund, Thomas

2017-01-01

Introduction The return-to-work (RTW) process after long-term sickness absence is often complex and long and implies multiple shifts between different labour market states for the absentee. Standard methods for examining RTW research typically rely on the analysis of one outcome measure at a time, which will not capture the many possible states and transitions the absentee can go through. The purpose of this study was to explore the potential added value of sequence analysis in supplement to standard regression analysis of a multidisciplinary RTW intervention among patients with low back pain (LBP). Methods The study population consisted of 160 patients randomly allocated to either a hospital-based brief or a multidisciplinary intervention. Data on labour market participation following intervention were obtained from a national register and analysed in two ways: as a binary outcome expressed as active or passive relief at a 1-year follow-up and as four different categories for labour market participation. Logistic regression and sequence analysis were performed. Results The logistic regression analysis showed no difference in labour market participation for patients in the two groups after 1 year. Applying sequence analysis showed differences in subsequent labour market participation after 2 years after baseline in favour of the brief intervention group versus the multidisciplinary intervention group. Conclusion The study indicated that sequence analysis could provide added analytical value as a supplement to traditional regression analysis in prospective studies of RTW among patients with LBP. PMID:28729315

Predictors of meaningful improvement in quality of life after temporal lobe epilepsy surgery: A prospective study.

PubMed

Pauli, Carla; Schwarzbold, Marcelo Liborio; Diaz, Alexandre Paim; de Oliveira Thais, Maria Emilia Rodrigues; Kondageski, Charles; Linhares, Marcelo Neves; Guarnieri, Ricardo; de Lemos Zingano, Bianca; Ben, Juliana; Nunes, Jean Costa; Markowitsch, Hans Joachim; Wolf, Peter; Wiebe, Samuel; Lin, Katia; Walz, Roger

2017-05-01

To investigate prospectively the independent predictors of a minimum clinically important change (MCIC) in quality of life (QOL) after anterior temporal lobectomy (ATL) for drug-resistant mesial temporal lobe epilepsy related to hippocampal sclerosis (MTLE-HS) in Brazilian patients. Multiple binary logistic regression analysis was performed to identify the clinical, demographic, radiologic, and electrophysiologic variables independently associated with MCIC in the Quality of Life in Epilepsy-31 Inventory (QOLIE-31) overall score 1 year after ATL in 77 consecutive patients with unilateral MTLE-HS. The overall QOLIE-31 score and all its subscale scores increased significantly (p < 0.0001) 1 year after ATL. In the final logistic regression model, absence of presurgical diagnosis of depression (adjusted odds ratio [OR] 4.4, 95% confidence interval [CI] 1.1-16.1, p = 0.02) and a complete postoperative seizure control (adjusted OR 4.1, 95% CI 1.2-14.5, p = 0.03) were independently associated with improvement equal to or greater than the MCIC in QOL after ATL. The overall model accuracy for MCIC improvement in the QOL was 85.6%, with a 95.2% of sensitivity and 46.7% of specificity. These results in Brazilian patients reinforce the external validation of previous findings in Canadian patients showing that presurgical depression and complete seizure control after surgery are independent predictors for meaningful improvement in QOL after ATL, and have implications for the surgical management of MTLE patients. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

[Relationship between family functioning and lifestyle in school-age adolescents].

PubMed

Lima-Serrano, Marta; Guerra-Martín, María Dolores; Lima-Rodríguez, Joaquín Salvador

Risk behaviors in adolescents can lead to serious disorders, therefore the objectives of this work are to characterize the lifestyles of teenagers about substance use, sex, and road safety, and to meet socio-demographic factors associated with these. A cross-sectional, descriptive and correlational study was conducted with 204 school-age-children from 12 to 17 years, in 2013. They were given a validated questionnaire about sociodemographic, family functioning, and lifestyles such as substance abuse, sexual intercourse and road safety. A descriptive and multivariate analysis was performed by using multiple linear regression in the case of quantitative dependent variables, and binary logistic regression models in the case of binary categories. Data analysis was based on SPSS 20.0, with a significance level of p<0.05. 32.4% of students had smoked, and 61.3% had drunk alcohol. 26% of adolescent between 14-17 years had sexual intercourse; the average age of the first sexual intercourse was 14.9 years. 85.2% used condoms. 94.6% respected traffic signs, 77.5% used to wear a seat belt and 81.9% a helmet. Family functioning, as protective factor, was the variable more frequently associated to risk behaviour: smoking (OR=7.06, p=.000), alcohol drinking (OR=3.97, p=.008), sexual intercourse (OR=3.67, p=.041), and road safety (β=1.82, p=.000). According the results, age, gender and family functioning are the main factors associated with the adoption of risk behaviors. This information is important for the development of public health policies, for instance health promotion at schools. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

The VLT-FLAMES Tarantula Survey. VIII. Multiplicity properties of the O-type star population

NASA Astrophysics Data System (ADS)

Sana, H.; de Koter, A.; de Mink, S. E.; Dunstall, P. R.; Evans, C. J.; Hénault-Brunet, V.; Maíz Apellániz, J.; Ramírez-Agudelo, O. H.; Taylor, W. D.; Walborn, N. R.; Clark, J. S.; Crowther, P. A.; Herrero, A.; Gieles, M.; Langer, N.; Lennon, D. J.; Vink, J. S.

2013-02-01

Context. The Tarantula Nebula in the Large Magellanic Cloud is our closest view of a starburst region and is the ideal environment to investigate important questions regarding the formation, evolution and final fate of the most massive stars. Aims: We analyze the multiplicity properties of the massive O-type star population observed through multi-epoch spectroscopy in the framework of the VLT-FLAMES Tarantula Survey. With 360 O-type stars, this is the largest homogeneous sample of massive stars analyzed to date. Methods: We use multi-epoch spectroscopy and variability analysis to identify spectroscopic binaries. We also use a Monte-Carlo method to correct for observational biases. By modeling simultaneously the observed binary fraction, the distributions of the amplitudes of the radial velocity variations and the distribution of the time scales of these variations, we constrain the intrinsic current binary fraction and period and mass-ratio distributions. Results: We observe a spectroscopic binary fraction of 0.35 ± 0.03, which corresponds to the fraction of objects displaying statistically significant radial velocity variations with an amplitude of at least 20 km s-1. We compute the intrinsic binary fraction to be 0.51 ± 0.04. We adopt power-laws to describe the intrinsic period and mass-ratio distributions: f(log 10P/d) ~ (log 10P/d)π (with log 10P/d in the range 0.15-3.5) and f(q) ~ qκ with 0.1 ≤ q = M2/M1 ≤ 1.0. The power-law indexes that best reproduce the observed quantities are π = -0.45 ± 0.30 and κ = -1.0 ± 0.4. The period distribution that we obtain thus favours shorter period systems compared to an Öpik law (π = 0). The mass ratio distribution is slightly skewed towards low mass ratio systems but remains incompatible with a random sampling of a classical mass function (κ = -2.35). The binary fraction seems mostly uniform across the field of view and independent of the spectral types and luminosity classes. The binary fraction in the outer region of the field of view (r > 7.8', i.e. ≈117 pc) and among the O9.7 I/II objects are however significantly lower than expected from statistical fluctuations. The observed and intrinsic binary fractions are also lower for the faintest objects in our sample (Ks > 15.5 mag), which results from observational effects and the fact that our O star sample is not magnitude-limited but is defined by a spectral-type cutoff. We also conclude that magnitude-limited investigations are biased towards larger binary fractions. Conclusions: Using the multiplicity properties of the O stars in the Tarantula region and simple evolutionary considerations, we estimate that over 50% of the current O star population will exchange mass with its companion within a binary system. This shows that binary interaction is greatly affecting the evolution and fate of massive stars, and must be taken into account to correctly interpret unresolved populations of massive stars. Based on observations collected at the European Southern Observatory under program ID 182.D-0222.Full Tables 1-3 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A107Appendices are available in electronic form at http://www.aanda.org

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhuang Quntao; Gao Xun; Yu Qingjuan, E-mail: yuqj@pku.edu.cn

In this paper, we study possible signatures of binary planets or exomoons on the Rossiter-McLaughlin (R-M) effect. Our analyses show that the R-M effect for a binary planet or an exomoon during its complete transit phase can be divided into two parts. The first is the conventional one similar to the R-M effect from the transit of a single planet, of which the mass and the projected area are the combinations of the binary components; the second is caused by the orbital rotation of the binary components, which may add a sine- or linear-mode deviation to the stellar radial velocitymore » curve. We find that the latter effect can be up to several ten m s{sup -1}. Our numerical simulations as well as analyses illustrate that the distribution and dispersion of the latter effects obtained from multiple transit events can be used to constrain the dynamical configuration of the binary planet, such as how the inner orbit of the binary planet is inclined to its orbit rotating around the central star. We find that the signatures caused by the orbital rotation of the binary components are more likely to be revealed if the two components of a binary planet have different masses and mass densities, especially if the heavy one has a high mass density and the light one has a low density. Similar signatures on the R-M effect may also be revealed in a hierarchical triple star system containing a dark compact binary and a tertiary star.« less

The cross-validated AUC for MCP-logistic regression with high-dimensional data.

PubMed

Jiang, Dingfeng; Huang, Jian; Zhang, Ying

2013-10-01

We propose a cross-validated area under the receiving operator characteristic (ROC) curve (CV-AUC) criterion for tuning parameter selection for penalized methods in sparse, high-dimensional logistic regression models. We use this criterion in combination with the minimax concave penalty (MCP) method for variable selection. The CV-AUC criterion is specifically designed for optimizing the classification performance for binary outcome data. To implement the proposed approach, we derive an efficient coordinate descent algorithm to compute the MCP-logistic regression solution surface. Simulation studies are conducted to evaluate the finite sample performance of the proposed method and its comparison with the existing methods including the Akaike information criterion (AIC), Bayesian information criterion (BIC) or Extended BIC (EBIC). The model selected based on the CV-AUC criterion tends to have a larger predictive AUC and smaller classification error than those with tuning parameters selected using the AIC, BIC or EBIC. We illustrate the application of the MCP-logistic regression with the CV-AUC criterion on three microarray datasets from the studies that attempt to identify genes related to cancers. Our simulation studies and data examples demonstrate that the CV-AUC is an attractive method for tuning parameter selection for penalized methods in high-dimensional logistic regression models.

Be discs in coplanar circular binaries: Phase-locked variations of emission lines

NASA Astrophysics Data System (ADS)

Panoglou, Despina; Faes, Daniel M.; Carciofi, Alex C.; Okazaki, Atsuo T.; Baade, Dietrich; Rivinius, Thomas; Borges Fernandes, Marcelo

2018-01-01

In this paper, we present the first results of radiative transfer calculations on decretion discs of binary Be stars. A smoothed particle hydrodynamics code computes the structure of Be discs in coplanar circular binary systems for a range of orbital and disc parameters. The resulting disc configuration consists of two spiral arms, and this can be given as input into a Monte Carlo code, which calculates the radiative transfer along the line of sight for various observational coordinates. Making use of the property of steady disc structure in coplanar circular binaries, observables are computed as functions of the orbital phase. Some orbital-phase series of line profiles are given for selected parameter sets under various viewing angles, to allow comparison with observations. Flat-topped profiles with and without superimposed multiple structures are reproduced, showing, for example, that triple-peaked profiles do not have to be necessarily associated with warped discs and misaligned binaries. It is demonstrated that binary tidal effects give rise to phase-locked variability of the violet-to-red (V/R) ratio of hydrogen emission lines. The V/R ratio exhibits two maxima per cycle; in certain cases those maxima are equal, leading to a clear new V/R cycle every half orbital period. This study opens a way to identifying binaries and to constraining the parameters of binary systems that exhibit phase-locked variations induced by tidal interaction with a companion star.

Cognitive Code-Division Channelization

DTIC Science & Technology

2011-04-01

22] G. N. Karystinos and D. A. Pados, “New bounds on the total squared correlation and optimum design of DS - CDMA binary signature sets,” IEEE Trans...Commun., vol. 51, pp. 48-51, Jan. 2003. [23] C. Ding, M. Golin, and T. Klve, “Meeting the Welch and Karystinos- Pados bounds on DS - CDMA binary...receiver pair coexisting with a primary code-division multiple-access ( CDMA ) system. Our objective is to find the optimum transmitting power and code

Deletion Diagnostics for Alternating Logistic Regressions

PubMed Central

Preisser, John S.; By, Kunthel; Perin, Jamie; Qaqish, Bahjat F.

2013-01-01

Deletion diagnostics are introduced for the regression analysis of clustered binary outcomes estimated with alternating logistic regressions, an implementation of generalized estimating equations (GEE) that estimates regression coefficients in a marginal mean model and in a model for the intracluster association given by the log odds ratio. The diagnostics are developed within an estimating equations framework that recasts the estimating functions for association parameters based upon conditional residuals into equivalent functions based upon marginal residuals. Extensions of earlier work on GEE diagnostics follow directly, including computational formulae for one-step deletion diagnostics that measure the influence of a cluster of observations on the estimated regression parameters and on the overall marginal mean or association model fit. The diagnostic formulae are evaluated with simulations studies and with an application concerning an assessment of factors associated with health maintenance visits in primary care medical practices. The application and the simulations demonstrate that the proposed cluster-deletion diagnostics for alternating logistic regressions are good approximations of their exact fully iterated counterparts. PMID:22777960

An Experimental Realization of a Chaos-Based Secure Communication Using Arduino Microcontrollers.

PubMed

Zapateiro De la Hoz, Mauricio; Acho, Leonardo; Vidal, Yolanda

2015-01-01

Security and secrecy are some of the important concerns in the communications world. In the last years, several encryption techniques have been proposed in order to improve the secrecy of the information transmitted. Chaos-based encryption techniques are being widely studied as part of the problem because of the highly unpredictable and random-look nature of the chaotic signals. In this paper we propose a digital-based communication system that uses the logistic map which is a mathematically simple model that is chaotic under certain conditions. The input message signal is modulated using a simple Delta modulator and encrypted using a logistic map. The key signal is also encrypted using the same logistic map with different initial conditions. In the receiver side, the binary-coded message is decrypted using the encrypted key signal that is sent through one of the communication channels. The proposed scheme is experimentally tested using Arduino shields which are simple yet powerful development kits that allows for the implementation of the communication system for testing purposes.

A simple and reliable multi-gene transformation method for switchgrass.

PubMed

Ogawa, Yoichi; Shirakawa, Makoto; Koumoto, Yasuko; Honda, Masaho; Asami, Yuki; Kondo, Yasuhiro; Hara-Nishimura, Ikuko

2014-07-01

A simple and reliable Agrobacterium -mediated transformation method was developed for switchgrass. Using this method, many transgenic plants carrying multiple genes-of-interest could be produced without untransformed escape. Switchgrass (Panicum virgatum L.) is a promising biomass crop for bioenergy. To obtain transgenic switchgrass plants carrying a multi-gene trait in a simple manner, an Agrobacterium-mediated transformation method was established by constructing a Gateway-based binary vector, optimizing transformation conditions and developing a novel selection method. A MultiRound Gateway-compatible destination binary vector carrying the bar selectable marker gene, pHKGB110, was constructed to introduce multiple genes of interest in a single transformation. Two reporter gene expression cassettes, GUSPlus and gfp, were constructed independently on two entry vectors and then introduced into a single T-DNA region of pHKGB110 via sequential LR reactions. Agrobacterium tumefaciens EHA101 carrying the resultant binary vector pHKGB112 and caryopsis-derived compact embryogenic calli were used for transformation experiments. Prolonged cocultivation for 7 days followed by cultivation on media containing meropenem improved transformation efficiency without overgrowth of Agrobacterium, which was, however, not inhibited by cefotaxime or Timentin. In addition, untransformed escape shoots were completely eliminated during the rooting stage by direct dipping the putatively transformed shoots into the herbicide Basta solution for a few seconds, designated as the 'herbicide dipping method'. It was also demonstrated that more than 90 % of the bar-positive transformants carried both reporters delivered from pHKGB112. This simple and reliable transformation method, which incorporates a new selection technique and the use of a MultiRound Gateway-based binary vector, would be suitable for producing a large number of transgenic lines carrying multiple genes.

Gaia Assorted Mass Binaries Long Excluded from SLoWPoKES (GAMBLES): Identifying Ultra-wide Binary Pairs with Components of Diverse Mass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oelkers, Ryan J.; Stassun, Keivan G.; Dhital, Saurav, E-mail: ryan.j.oelkers@vanderbilt.edu

The formation and evolution of binary star systems are some of the remaining key questions in modern astronomy. Wide binary pairs (separations >10{sup 3} au) are particularly intriguing because their low binding energies make it difficult for the stars to stay gravitationally bound over extended timescales, and thus to probe the dynamics of binary formation and dissolution. Our previous SLoWPoKES catalogs, I and II, provided the largest and most complete sample of wide-binary pairs of low masses. Here we present an extension of these catalogs to a broad range of stellar masses: the Gaia Assorted Mass Binaries Long Excluded frommore » SloWPoKES (GAMBLES), comprising 8660 statistically significant wide pairs that we make available in a living online database. Within this catalog we identify a subset of 543 long-lived (dissipation timescale >1.5 Gyr) candidate binary pairs, of assorted mass, with typical separations between 10{sup 3} and 10{sup 5.5} au (0.002–1.5 pc), using the published distances and proper motions from the Tycho -Gaia Astrometric Solution and Sloan Digital Sky Survey photometry. Each pair has at most a false positive probability of 0.05; the total expectation is 2.44 false binaries in our sample. Among these, we find 22 systems with 3 components, 1 system with 4 components, and 15 pairs consisting of at least 1 possible red giant. We find the largest long-lived binary separation to be nearly 3.2 pc; even so, >76% of GAMBLES long-lived binaries have large binding energies and dissipation lifetimes longer than 1.5 Gyr. Finally, we find that the distribution of binary separations is clearly bimodal, corroborating the findings from SloWPoKES and suggesting multiple pathways for the formation and dissipation of the widest binaries in the Galaxy.« less

Gaia Assorted Mass Binaries Long Excluded from SLoWPoKES (GAMBLES): Identifying Ultra-wide Binary Pairs with Components of Diverse Mass

NASA Astrophysics Data System (ADS)

Oelkers, Ryan J.; Stassun, Keivan G.; Dhital, Saurav

2017-06-01

The formation and evolution of binary star systems are some of the remaining key questions in modern astronomy. Wide binary pairs (separations >103 au) are particularly intriguing because their low binding energies make it difficult for the stars to stay gravitationally bound over extended timescales, and thus to probe the dynamics of binary formation and dissolution. Our previous SLoWPoKES catalogs, I and II, provided the largest and most complete sample of wide-binary pairs of low masses. Here we present an extension of these catalogs to a broad range of stellar masses: the Gaia Assorted Mass Binaries Long Excluded from SloWPoKES (GAMBLES), comprising 8660 statistically significant wide pairs that we make available in a living online database. Within this catalog we identify a subset of 543 long-lived (dissipation timescale >1.5 Gyr) candidate binary pairs, of assorted mass, with typical separations between 103 and 105.5 au (0.002-1.5 pc), using the published distances and proper motions from the Tycho-Gaia Astrometric Solution and Sloan Digital Sky Survey photometry. Each pair has at most a false positive probability of 0.05; the total expectation is 2.44 false binaries in our sample. Among these, we find 22 systems with 3 components, 1 system with 4 components, and 15 pairs consisting of at least 1 possible red giant. We find the largest long-lived binary separation to be nearly 3.2 pc even so, >76% of GAMBLES long-lived binaries have large binding energies and dissipation lifetimes longer than 1.5 Gyr. Finally, we find that the distribution of binary separations is clearly bimodal, corroborating the findings from SloWPoKES and suggesting multiple pathways for the formation and dissipation of the widest binaries in the Galaxy.

Low Complexity Track Initialization and Fusion for Multi-Modal Sensor Networks

DTIC Science & Technology

2012-11-08

feature was demonstrated via the simulations. Aerospace 2011work further documents our investigation of multiple target tracking filters in...bounds that determine how well a sensor network can resolve and localize multiple targets as a function of the operating parameters such as sensor...probability density (PHD) filter for binary measurements using proximity sensors. 15. SUBJECT TERMS proximity sensors, PHD filter, multiple

Planet Formation in Binaries

NASA Astrophysics Data System (ADS)

Thebault, P.; Haghighipour, N.

Spurred by the discovery of numerous exoplanets in multiple systems, binaries have become in recent years one of the main topics in planet formation research. Numerous studies have investigated to what extent the presence of a stellar companion can affect the planet formation process. Such studies have implications that can reach beyond the sole context of binaries, as they allow to test certain aspects of the planet formation scenario by submitting them to extreme environments. We review here the current understanding on this complex problem. We show in particular how each of the different stages of the planet-formation process is affected differently by binary perturbations. We focus especially on the intermediate stage of kilometre-sized planetesimal accretion, which has proven to be the most sensitive to binarity and for which the presence of some exoplanets observed in tight binaries is difficult to explain by in-situ formation following the "standard" planet-formation scenario. Some tentative solutions to this apparent paradox are presented. The last part of our review presents a thorough description of the problem of planet habitability, for which the binary environment creates a complex situation because of the presence of two irradation sources of varying distance.

Performance Analysis of New Binary User Codes for DS-CDMA Communication

NASA Astrophysics Data System (ADS)

Usha, Kamle; Jaya Sankar, Kottareddygari

2016-03-01

This paper analyzes new binary spreading codes through correlation properties and also presents their performance over additive white Gaussian noise (AWGN) channel. The proposed codes are constructed using gray and inverse gray codes. In this paper, a n-bit gray code appended by its n-bit inverse gray code to construct the 2n-length binary user codes are discussed. Like Walsh codes, these binary user codes are available in sizes of power of two and additionally code sets of length 6 and their even multiples are also available. The simple construction technique and generation of code sets of different sizes are the salient features of the proposed codes. Walsh codes and gold codes are considered for comparison in this paper as these are popularly used for synchronous and asynchronous multi user communications respectively. In the current work the auto and cross correlation properties of the proposed codes are compared with those of Walsh codes and gold codes. Performance of the proposed binary user codes for both synchronous and asynchronous direct sequence CDMA communication over AWGN channel is also discussed in this paper. The proposed binary user codes are found to be suitable for both synchronous and asynchronous DS-CDMA communication.

On the gravitational wave background from black hole binaries after the first LIGO detections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cholis, Ilias, E-mail: icholis1@jhu.edu

The detection of gravitational waves from the merger of binary black holes by the LIGO Collaboration has opened a new window to astrophysics. With the sensitivities of ground based detectors in the coming years, we will principally detect local binary black hole mergers. The integrated merger rate can instead be probed by the gravitational-wave background, the incoherent superposition of the released energy in gravitational waves during binary-black-hole coalescence. Through that, the properties of the binary black holes can be studied. In this work we show that by measuring the energy density Ω{sub GW} (in units of the cosmic critical density)more » of the gravitational-wave background, we can search for the rare ∼ 100 M {sub ⊙} massive black holes formed in the Universe. In addition, we can answer how often the least massive BHs of mass ≳ 3 M {sub ⊙} form. Finally, if there are multiple channels for the formation of binary black holes and if any of them predicts a narrow mass range for the black holes, then the total Ω{sub GW} spectrum may have features that with the future Einstein Telescope can be detected.« less

Nonparametric statistical modeling of binary star separations

NASA Technical Reports Server (NTRS)

Heacox, William D.; Gathright, John

1994-01-01

We develop a comprehensive statistical model for the distribution of observed separations in binary star systems, in terms of distributions of orbital elements, projection effects, and distances to systems. We use this model to derive several diagnostics for estimating the completeness of imaging searches for stellar companions, and the underlying stellar multiplicities. In application to recent imaging searches for low-luminosity companions to nearby M dwarf stars, and for companions to young stars in nearby star-forming regions, our analyses reveal substantial uncertainty in estimates of stellar multiplicity. For binary stars with late-type dwarf companions, semimajor axes appear to be distributed approximately as a(exp -1) for values ranging from about one to several thousand astronomical units. About one-quarter of the companions to field F and G dwarf stars have semimajor axes less than 1 AU, and about 15% lie beyond 1000 AU. The geometric efficiency (fraction of companions imaged onto the detector) of imaging searches is nearly independent of distances to program stars and orbital eccentricities, and varies only slowly with detector spatial limitations.

Searching for Partners of Cool Senior Citizens

NASA Astrophysics Data System (ADS)

Jao, Wei-Chun; Henry, T. J.

2012-01-01

Mass is one of the most fundamental parameters in stellar astronomy. In order to measure dynamical masses, one needs to find nearby binary systems that can be resolved and monitored, ideally with orbital periods that completely wrap in a reasonable amount of time. Many surveys have been made of nearby main sequence dwarfs, and their mass-luminosity relation is well established. As part of our Cool Subdwarf Investigations (CSI) program, we are searching for subdwarf binaries of spectral types K and M within 60 parsecs to measure their multiplicity rate and to reveal binaries appropriate for mass determinations. Here we present results of our CSI work using HST's Fine Guidance Sensors. When combined with previous CSI work and results in the literature, we find the multiplicity rate of subdwarfs, 21%, to be surprisingly low compared to that of similar main sequence K and M stars, 37%. This work has several implications, including that the star formation and/or evolution history of subdwarfs is different than for dwarfs, and that ideal systems for subdwarf mass determinations are difficult to find. This work is supported by HST grant GO-11943.

The L dwarf/T dwarf transition: Multiplicity, magnetic activity and mineral meteorology across the hydrogen burning limit

NASA Astrophysics Data System (ADS)

Burgasser, A. J.

2013-02-01

The transition between the L dwarf and T dwarf spectral classes is one of the most remarkable along the stellar/brown dwarf main sequence, separating sources with photospheres containing mineral condensate clouds from those containing methane and ammonia gases. Unusual characteristics of this transition include a 1 μm brightening between late L and early T dwarfs observed in both parallax samples and coeval binaries; a spike in the multiplicity fraction; evidence of increased photometric variability, possibly arising from patchy cloud structures; and a delayed transition for young, planetary-mass objects. All of these features can be explained if this transition is governed by the ``rapid'' (nonequlibrium) rainout of clouds from the photosphere, triggered by temperature, surface gravity, metallicity and (perhaps) rotational effects. While the underlying mechanism of this rainout remains under debate, the transition is now being exploited to discover and precisely characterize tight (<1 AU) very low-mass binaries that can be used to test brown dwarf evolutionary and atmospheric theories, and resolved binaries that further constrain the properties of this remarkable transition.

Numerical Modelling of Tertiary Tides

NASA Astrophysics Data System (ADS)

Gao, Yan; Correia, Alexandre C. M.; Eggleton, Peter P.; Han, Zhanwen

2018-06-01

Stellar systems consisting of multiple stars tend to undergo tidal interactions when the separations between the stars are short. While tidal phenomena have been extensively studied, a certain tidal effect exclusive to hierarchical triples (triples in which one component star has a much wider orbit than the others) has hardly received any attention, mainly due to its complexity and consequent resistance to being modelled. This tidal effect is the tidal perturbation of the tertiary by the inner binary, which in turn depletes orbital energy from the inner binary, causing the inner binary separation to shrink. In this paper, we develop a fully numerical simulation of these "tertiary tides" by modifying established tidal models. We also provide general insight as to how close a hierarchical triple needs to be in order for such an effect to take place, and demonstrate that our simulations can effectively retrieve the orbital evolution for such systems. We conclude that tertiary tides are a significant factor in the evolution of close hierarchical triples, and strongly influence at least ˜1% of all multiple star systems.

A Multiple-star Combined Solution Program - Application to the Population II Binary μ Cas

NASA Astrophysics Data System (ADS)

Gudehus, D. H.

2001-05-01

A multiple-star combined-solution computer program which can simultaneously fit astrometric, speckle, and spectroscopic data, and solve for the orbital parameters, parallax, proper motion, and masses has been written and is now publicly available. Some features of the program are the ability to scale the weights at run time, hold selected parameters constant, handle up to five spectroscopic subcomponents for the primary and the secondary each, account for the light travel time across the system, account for apsidal motion, plot the results, and write the residuals in position to a standard file for further analysis. The spectroscopic subcomponent data can be represented by reflex velocities and/or by independent measurements. A companion editing program which can manage the data files is included in the package. The program has been applied to the Population II binary μ Cas to derive improved masses and an estimate of the primordial helium abundance. The source code, executables, sample data files, and documentation for OpenVMS and Unix, including Linux, are available at http://www.chara.gsu.edu/\\rlap\\ \\ gudehus/binary.html.

Three quantitative approaches to the diagnosis of abdominal pain in children: practical applications of decision theory.

PubMed

Klein, M D; Rabbani, A B; Rood, K D; Durham, T; Rosenberg, N M; Bahr, M J; Thomas, R L; Langenburg, S E; Kuhns, L R

2001-09-01

The authors compared 3 quantitative methods for assisting clinicians in the differential diagnosis of abdominal pain in children, where the most common important endpoint is whether the patient has appendicitis. Pretest probability in different age and sex groups were determined to perform Bayesian analysis, binary logistic regression was used to determine which variables were statistically significantly likely to contribute to a diagnosis, and recursive partitioning was used to build decision trees with quantitative endpoints. The records of all children (1,208) seen at a large urban emergency department (ED) with a chief complaint of abdominal pain were immediately reviewed retrospectively (24 to 72 hours after the encounter). Attempts were made to contact all the patients' families to determine an accurate final diagnosis. A total of 1,008 (83%) families were contacted. Data were analyzed by calculation of the posttest probability, recursive partitioning, and binary logistic regression. In all groups the most common diagnosis was abdominal pain (ICD-9 Code 789). After this, however, the order of the most common final diagnoses for abdominal pain varied significantly. The entire group had a pretest probability of appendicitis of 0.06. This varied with age and sex from 0.02 in boys 2 to 5 years old to 0.16 in boys older than 12 years. In boys age 5 to 12, recursive partitioning and binary logistic regression agreed on guarding and anorexia as important variables. Guarding and tenderness were important in girls age 5 to 12. In boys age greater than 12, both agreed on guarding and anorexia. Using sensitivities and specificities from the literature, computed tomography improved the posttest probability for the group from.06 to.33; ultrasound improved it from.06 to.48; and barium enema improved it from.06 to.58. Knowing the pretest probabilities in a specific population allows the physician to evaluate the likely diagnoses first. Other quantitative methods can help judge how much importance a certain criterion should have in the decision making and how much a particular test is likely to influence the probability of a correct diagnosis. It now should be possible to make these sophisticated quantitative methods readily available to clinicians via the computer. Copyright 2001 by W.B. Saunders Company.

Is parenting style a predictor of suicide attempts in a representative sample of adolescents?

PubMed Central

2014-01-01

Background Suicidal ideation and suicide attempts are serious but not rare conditions in adolescents. However, there are several research and practical suicide-prevention initiatives that discuss the possibility of preventing serious self-harm. Profound knowledge about risk and protective factors is therefore necessary. The aim of this study is a) to clarify the role of parenting behavior and parenting styles in adolescents’ suicide attempts and b) to identify other statistically significant and clinically relevant risk and protective factors for suicide attempts in a representative sample of German adolescents. Methods In the years 2007/2008, a representative written survey of N = 44,610 students in the 9th grade of different school types in Germany was conducted. In this survey, the lifetime prevalence of suicide attempts was investigated as well as potential predictors including parenting behavior. A three-step statistical analysis was carried out: I) As basic model, the association between parenting and suicide attempts was explored via binary logistic regression controlled for age and sex. II) The predictive values of 13 additional potential risk/protective factors were analyzed with single binary logistic regression analyses for each predictor alone. Non-significant predictors were excluded in Step III. III) In a multivariate binary logistic regression analysis, all significant predictor variables from Step II and the parenting styles were included after testing for multicollinearity. Results Three parental variables showed a relevant association with suicide attempts in adolescents – (all protective): mother’s warmth and father’s warmth in childhood and mother’s control in adolescence (Step I). In the full model (Step III), Authoritative parenting (protective: OR: .79) and Rejecting-Neglecting parenting (risk: OR: 1.63) were identified as significant predictors (p < .001) for suicidal attempts. Seven further variables were interpreted to be statistically significant and clinically relevant: ADHD, female sex, smoking, Binge Drinking, absenteeism/truancy, migration background, and parental separation events. Conclusions Parenting style does matter. While children of Authoritative parents profit, children of Rejecting-Neglecting parents are put at risk – as we were able to show for suicide attempts in adolescence. Some of the identified risk factors contribute new knowledge and potential areas of intervention for special groups such as migrants or children diagnosed with ADHD. PMID:24766881

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokovinin, Andrei, E-mail: atokovinin@ctio.noao.edu

To improve the statistics of hierarchical multiplicity, secondary components of wide nearby binaries with solar-type primaries were surveyed at the SOAR telescope for evaluating the frequency of subsystems. Images of 17 faint secondaries were obtained with the SOAR Adaptive Module that improved the seeing; one new 0.''2 binary was detected. For all targets, photometry in the g', i', z' bands is given. Another 46 secondaries were observed by speckle interferometry, resolving 7 close subsystems. Adding literature data, the binarity of 95 secondary components is evaluated. We found that the detection-corrected frequency of secondary subsystems with periods in the well-surveyed rangemore » from 10{sup 3} to 10{sup 5} days is 0.21 ± 0.06—same as the normal frequency of such binaries among solar-type stars, 0.18. This indicates that wide binaries are unlikely to be produced by dynamical evolution of N-body systems, but are rather formed by fragmentation.« less

Anomalies in the Spectra of the Uncorrelated Components of the Electric Field of the Earth at Frequencies that are Multiples of the Frequencies of Rotation of Relativistic Binary Star Systems

NASA Astrophysics Data System (ADS)

Grunskaya, L. V.; Isakevich, V. V.; Isakevich, D. V.

2018-05-01

A system is constructed, which, on the basis of extensive experimental material and the use of eigenoscopy, has allowed us to detect anomalies in the spectra of uncorrelated components localized near the rotation frequencies and twice the rotation frequencies of relativistic binary star systems with vanishingly low probability of false alarm, not exceeding 10-17.

Controlling total spot power from holographic laser by superimposing a binary phase grating.

PubMed

Liu, Xiang; Zhang, Jian; Gan, Yu; Wu, Liying

2011-04-25

By superimposing a tunable binary phase grating with a conventional computer-generated hologram, the total power of multiple holographic 3D spots can be easily controlled by changing the phase depth of grating with high accuracy to a random power value for real-time optical manipulation without extra power loss. Simulation and experiment results indicate that a resolution of 0.002 can be achieved at a lower time cost for normalized total spot power.

First trimester vaginal bleeding and adverse pregnancy outcomes among Chinese women: from a large cohort study in China.

PubMed

Sun, Lu; Tao, Fangbiao; Hao, Jiahu; Su, Puyu; Liu, Fang; Xu, Rong

2012-08-01

To examine the effect of first trimester vaginal bleeding on adverse pregnancy outcomes including preterm delivery, low birth weight and small for gestational age. This is a prospective population-based cohort study. A questionnaire survey was conducted on 4342 singleton pregnancies by trained doctors. Binary logistic regression was used to estimate risk ratios (RRs) and 95% confidence intervals (95% CI). Vaginal bleeding occurred among 1050 pregnant women, the incidence of vaginal bleeding was 24.2%, 37.4% of whom didn't see a doctor, 62.6% of whom saw a doctor for vaginal bleeding. Binary logistic regression demonstrated that bleeding with seeing a doctor was significantly associated with preterm birth (RR 1.84, 95% CI 1.25-2.69) and bleeding without seeing a doctor was related to increased of low birth weight (RR 2.52, 95% CI 1.34-4.75) and was 1.97-fold increased of small for gestational age (RR 1.97, 95% CI 1.19-3.25). These results suggest that first trimester vaginal bleeding is an increased risk of low birth weight, preterm delivery and small for gestational age. Find ways to reduce the risk of vaginal bleeding and lower vaginal bleeding rate may be helpful to reduce the incidence of preterm birth, low birth weight and small for gestational age.

National health insurance subscription and maternal healthcare utilisation across mothers' wealth status in Ghana.

PubMed

Ameyaw, Edward Kwabena; Kofinti, Raymond Elikplim; Appiah, Francis

2017-12-01

This study is against the backdrop that despite the forty-nine percent decline in Maternal Mortality Rate in Ghana, the situation still remains high averaging 319 per 100,000 live births between 2011 and 2015. To examine the relationship between National Health Insurance and maternal healthcare utilisation across three main wealth quintiles (Poor, Middle and Rich). The study employed data from the 2014 Ghana Demographic and Health Survey. Both descriptive analysis and binary logistic regression were conducted. Descriptively, rich women had high antenatal attendance and health facility deliveries represented by 96.5% and 95.6% respectively. However, the binary logistic regression results revealed that poor women owning NHIS are 7% (CI = 1.76-2.87) more likely to make at least four antenatal care visits compared to women in the middle wealth quintile (5%, CI = 2.12-4.76) and rich women (2%, CI = 1.14-4.14). Similarly, poor women who owned the NHIS are 14% (CI = 1.42-2.13) likely to deliver in health facility than women in the middle and rich wealth quintile. The study has vindicated the claim that NHIS Scheme is pro-poor in Ghana. The Ministry of Health should target women in the rural area to be enrolled on the NHIS to improve maternal healthcare utilisation since poverty is principally a rural phenomenon in Ghana.

Prevalence and determinants of cardiovascular disease risk factors among the residents of urban community housing projects in Malaysia

PubMed Central

2014-01-01

Objectives The objectives are to assess the prevalence and determinants of cardiovascular disease (CVD) risk factors among the residents of Community Housing Projects in metropolitan Kuala Lumpur, Malaysia. Method By using simple random sampling, we selected and surveyed 833 households which comprised of 3,722 individuals. Out of the 2,360 adults, 50.5% participated in blood sampling and anthropometric measurement sessions. Uni and bivariate data analysis and multivariate binary logistic regression were applied to identify demographic and socioeconomic determinants of the existence of having at least one CVD risk factor. Results As a Result, while obesity (54.8%), hypercholesterolemia (51.5%), and hypertension (39.3%) were the most common CVD risk factors among the low-income respondents, smoking (16.3%), diabetes mellitus (7.8%) and alcohol consumption (1.4%) were the least prevalent. Finally, the results from the multivariate binary logistic model illustrated that compared to the Malays, the Indians were 41% less likely to have at least one of the CVD risk factors (OR = 0.59; 95% CI: 0.37 - 0.93). Conclusion In Conclusion, the low-income individuals were at higher risk of developing CVDs. Prospective policies addressing preventive actions and increased awareness focusing on low-income communities are highly recommended and to consider age, gender, ethnic backgrounds, and occupation classes. PMID:25436515

Portugal and Angola: similarities and differences in Toxoplasma gondii seroprevalence and risk factors in pregnant women.

PubMed

Lobo, M L; Patrocinio, G; Sevivas, T; DE Sousa, B; Matos, O

2017-01-01

In this study we determined the presence of IgM/IgG antibodies to Toxoplasma gondii in sera of 155 and 300 pregnant women from Lisbon (Portugal) and Luanda (Angola), respectively, and evaluated the potential risk factors associated with this infection. DNA detection was performed by PCR assays targeting T. gondii regions (RE/B1). Overall, 21·9% (10·9% IgG, 10·9% IgG/IgM) of the Lisbon women and 27·3% (23·7%, IgG, 2% IgM, 1·7% IgG/IgM) of the Luanda women had antibodies to T. gondii. Single variable and binary logistic regression analyses were conducted. Based on the latter, contacts with cats (family/friends), and having more than two births were identified as risk factors for Toxoplasma infection in Lisbon women. In Luanda, the risk factors for T. gondii infection suggested by the single variable analysis (outdoor contact with cats and consumption of pasteurized milk/dairy products) were not confirmed by binary logistic regression. This study shows original data from Angola, and updated data from Portugal in the study of infection by T. gondii in pregnant women, indicating that the prevalence of anti-Toxoplasma antibodies is high enough to alert the government health authorities and implement appropriate measures to control this infection.

Exploring stop-go decision zones at rural high-speed intersections with flashing green signal and insufficient yellow time in China.

PubMed

Tang, Keshuang; Xu, Yanqing; Wang, Fen; Oguchi, Takashi

2016-10-01

The objective of this study is to empirically analyze and model the stop-go decision behavior of drivers at rural high-speed intersections in China, where a flashing green signal of 3s followed by a yellow signal of 3s is commonly applied to end a green phase. 1, 186 high-resolution vehicle trajectories were collected at four typical high-speed intersection approaches in Shanghai and used for the identification of actual stop-go decision zones and the modeling of stop-go decision behavior. Results indicate that the presence of flashing green significantly changed the theoretical decision zones based on the conventional Dilemma Zone theory. The actual stop-go decision zones at the study intersections were thus formulated and identified based on the empirical data. Binary Logistic model and Fuzzy Logic model were then developed to further explore the impacts of flashing green on the stop-go behavior of drivers. It was found that the Fuzzy Logic model could produce comparably good estimation results as compared to the traditional Binary Logistic models. The findings of this study could contribute the development of effective dilemma zone protection strategies, the improvement of stop-go decision model embedded in the microscopic traffic simulation software and the proper design of signal change and clearance intervals at high-speed intersections in China. Copyright © 2016 Elsevier Ltd. All rights reserved.

Depression and incident dementia. An 8-year population-based prospective study.

PubMed

Luppa, Melanie; Luck, Tobias; Ritschel, Franziska; Angermeyer, Matthias C; Villringer, Arno; Riedel-Heller, Steffi G

2013-01-01

The aim of the study was to investigate the impact of depression (categorical diagnosis; major depression, MD) and depressive symptoms (dimensional diagnosis and symptom patterns) on incident dementia in the German general population. Within the Leipzig Longitudinal Study of the Aged (LEILA 75+), a representative sample of 1,265 individuals aged 75 years and older were interviewed every 1.5 years over 8 years (mean observation time 4.3 years; mean number of visits 4.2). Cox proportional hazards and binary logistic regressions were used to estimate the effect of baseline depression and depressive symptoms on incident dementia. The incidence of dementia was 48 per 1,000 person-years (95% confidence interval (CI) 45-51). Depressive symptoms (Hazard ratio HR 1.03, 95% CI 1.01-1.05), and in particular mood-related symptoms (HR 1.08, 95% CI 1.03-1.14), showed a significant impact on the incidence of dementia only in univariate analysis, but not after adjustment for cognitive and functional impairment. MD showed only a significant impact on incidence of dementia in Cox proportional hazards regression, but not in binary logistic regression models. The present study using different diagnostic measures of depression on future dementia found no clear significant associations of depression and incident dementia. Further in-depth investigation would help to understand the nature of depression in the context of incident dementia.

Prevalence and Extrinsic Risk Factors for Dental Erosion in Adolescents.

PubMed

Mafla, Ana C; Cerón-Bastidas, Ximena A; Munoz-Ceballos, Maria E; Vallejo-Bravo, Diana C; Fajardo-Santacruz, Maria C

This manuscript examined the prevalence and extrinsic risk factors for dental erosion (DE) in early and middle adolescents in Pasto, Colombia. Dental erosion was evaluated in a random sample of 384 individuals aged 10-15 years attending three primary and high schools in this cross-sectional study. Clinical dental assessment for DE was done using O'Sullivan index. Data on general sociodemographic variables and extrinsic risks factors were obtained. Descriptive and univariate binary logistic regression analyses were performed. Dental erosion was observed in 57.3% of individuals. The univariate binary logistic regression analysis showed that frequency of drinking natural fruit juices (OR 2.670, 95% CI 1.346 - 5.295, P=0.004) and their pH (OR 2.303, 95% CI 1.292 - 4.107, P=0.004) were more associated with the odd of DE in early adolescence. However, a high SES (OR 10.360, 95% CI 3.700 - 29.010, P<0.001) and frequency of snacks with artificial lemon taste (OR 3.659, 95% CI 1.506 - 8.891, P=0.003) were highly associated with the risk of DE in middle adolescence. The results suggest that DE is a prevalent condition in adolescents living in a city in southern Colombia. The transition from early to middle adolescence implies new bio-psychosocial changes, which increase the risk for DE.

Cerebrovascular risk factors for patients with cerebral watershed infarction: A case-control study based on computed tomography angiography in a population from Southwest China.

PubMed

Dong, Mei-Xue; Hu, Ling; Huang, Yuan-Jun; Xu, Xiao-Min; Liu, Yang; Wei, You-Dong

2017-07-01

To determine cerebrovascular risk factors for patients with cerebral watershed infarction (CWI) from Southwest China.Patients suffering from acute ischemic stroke were categorized into internal CWI (I-CWI), external CWI (E-CWI), or non-CWI (patients without CWI) groups. Clinical data were collected and degrees of steno-occlusion of all cerebral arteries were scored. Arteries associated with the circle of Willis were also assessed. Data were compared using Pearson chi-squared tests for categorical data and 1-way analysis of variance with Bonferroni post hoc tests for continuous data, as appropriate. Multivariate binary logistic regression analysis was performed to determine independent cerebrovascular risk factors for CWI.Compared with non-CWI, I-CWI had higher degrees of steno-occlusion of the ipsilateral middle cerebral artery, ipsilateral carotid artery, and contralateral middle cerebral artery. E-CWI showed no significant differences. All the 3 arteries were independent cerebrovascular risk factors for I-CWI confirmed by multivariate binary logistic regression analysis. I-CWI had higher degrees of steno-occlusion of the ipsilateral middle cerebral artery compared with E-CWI. No significant differences were found among arteries associated with the circle of Willis.The ipsilateral middle cerebral artery, carotid artery, and contralateral middle cerebral artery were independent cerebrovascular risk factors for I-CWI. No cerebrovascular risk factor was identified for E-CWI.

A binary logistic regression model with complex sampling design of unmet need for family planning among all women aged (15-49) in Ethiopia.

PubMed

Workie, Demeke Lakew; Zike, Dereje Tesfaye; Fenta, Haile Mekonnen; Mekonnen, Mulusew Admasu

2017-09-01

Unintended pregnancy related to unmet need is a worldwide problem that affects societies. The main objective of this study was to identify the prevalence and determinants of unmet need for family planning among women aged (15-49) in Ethiopia. The Performance Monitoring and Accountability2020/Ethiopia was conducted in April 2016 at round-4 from 7494 women with two-stage-stratified sampling. Bi-variable and multi-variable binary logistic regression model with complex sampling design was fitted. The prevalence of unmet-need for family planning was 16.2% in Ethiopia. Women between the age range of 15-24 years were 2.266 times more likely to have unmet need family planning compared to above 35 years. Women who were currently married were about 8 times more likely to have unmet need family planning compared to never married women. Women who had no under-five child were 0.125 times less likely to have unmet need family planning compared to those who had more than two-under-5. The key determinants of unmet need family planning in Ethiopia were residence, age, marital-status, education, household members, birth-events and number of under-5 children. Thus the Government of Ethiopia would take immediate steps to address the causes of high unmet need for family planning among women.

Psychological trauma symptoms and Type 2 diabetes prevalence, glucose control, and treatment modality among American Indians in the Strong Heart Family Study

PubMed Central

Jacob, Michelle M.; Gonzales, Kelly L.; Calhoun, Darren; Beals, Janette; Muller, Clemma Jacobsen; Goldberg, Jack; Nelson, Lonnie; Welty, Thomas K.; Howard, Barbara V.

2013-01-01

Aims The aims of this paper are to examine the relationship between psychological trauma symptoms and Type 2 diabetes prevalence, glucose control, and treatment modality among 3,776 American Indians in Phase V of the Strong Heart Family Study. Methods This cross-sectional analysis measured psychological trauma symptoms using the National Anxiety Disorder Screening Day instrument, diabetes by American Diabetes Association criteria, and treatment modality by four categories: no medication, oral medication only, insulin only, or both oral medication and insulin. We used binary logistic regression to evaluate the association between psychological trauma symptoms and diabetes prevalence. We used ordinary least squares regression to evaluate the association between psychological trauma symptoms and glucose control. We used binary logistic regression to model the association of psychological trauma symptoms with treatment modality. Results Neither diabetes prevalence (22-31%; p = 0.19) nor control (8.0-8.6; p = 0.25) varied significantly by psychological trauma symptoms categories. However, diabetes treatment modality was associated with psychological trauma symptoms categories, as people with greater burden used either no medication, or both oral and insulin medications (odds ratio = 3.1, p < 0.001). Conclusions The positive relationship between treatment modality and psychological trauma symptoms suggests future research investigate patient and provider treatment decision making. PMID:24051029

Secular dynamics of hierarchical multiple systems composed of nested binaries, with an arbitrary number of bodies and arbitrary hierarchical structure - II. External perturbations: flybys and supernovae

NASA Astrophysics Data System (ADS)

Hamers, Adrian S.

2018-05-01

We extend the formalism of a previous paper to include the effects of flybys and instantaneous perturbations such as supernovae on the long-term secular evolution of hierarchical multiple systems with an arbitrary number of bodies and hierarchy, provided that the system is composed of nested binary orbits. To model secular encounters, we expand the Hamiltonian in terms of the ratio of the separation of the perturber with respect to the barycentre of the multiple system, to the separation of the widest orbit. Subsequently, we integrate over the perturber orbit numerically or analytically. We verify our method for secular encounters and illustrate it with an example. Furthermore, we describe a method to compute instantaneous orbital changes to multiple systems, such as asymmetric supernovae and impulsive encounters. The secular code, with implementation of the extensions described in this paper, is publicly available within AMUSE, and we provide a number of simple example scripts to illustrate its usage for secular and impulsive encounters and asymmetric supernovae. The extensions presented in this paper are a next step towards efficiently modelling the evolution of complex multiple systems embedded in star clusters.

Mediation Analysis with Multiple Mediators

PubMed Central

VanderWeele, T.J.; Vansteelandt, S.

2014-01-01

Recent advances in the causal inference literature on mediation have extended traditional approaches to direct and indirect effects to settings that allow for interactions and non-linearities. In this paper, these approaches from causal inference are further extended to settings in which multiple mediators may be of interest. Two analytic approaches, one based on regression and one based on weighting are proposed to estimate the effect mediated through multiple mediators and the effects through other pathways. The approaches proposed here accommodate exposure-mediator interactions and, to a certain extent, mediator-mediator interactions as well. The methods handle binary or continuous mediators and binary, continuous or count outcomes. When the mediators affect one another, the strategy of trying to assess direct and indirect effects one mediator at a time will in general fail; the approach given in this paper can still be used. A characterization is moreover given as to when the sum of the mediated effects for multiple mediators considered separately will be equal to the mediated effect of all of the mediators considered jointly. The approach proposed in this paper is robust to unmeasured common causes of two or more mediators. PMID:25580377

Mediation Analysis with Multiple Mediators.

PubMed

VanderWeele, T J; Vansteelandt, S

2014-01-01

Recent advances in the causal inference literature on mediation have extended traditional approaches to direct and indirect effects to settings that allow for interactions and non-linearities. In this paper, these approaches from causal inference are further extended to settings in which multiple mediators may be of interest. Two analytic approaches, one based on regression and one based on weighting are proposed to estimate the effect mediated through multiple mediators and the effects through other pathways. The approaches proposed here accommodate exposure-mediator interactions and, to a certain extent, mediator-mediator interactions as well. The methods handle binary or continuous mediators and binary, continuous or count outcomes. When the mediators affect one another, the strategy of trying to assess direct and indirect effects one mediator at a time will in general fail; the approach given in this paper can still be used. A characterization is moreover given as to when the sum of the mediated effects for multiple mediators considered separately will be equal to the mediated effect of all of the mediators considered jointly. The approach proposed in this paper is robust to unmeasured common causes of two or more mediators.

Walking Performance: Correlation between Energy Cost of Walking and Walking Participation. New Statistical Approach Concerning Outcome Measurement

PubMed Central

Franceschini, Marco; Rampello, Anais; Agosti, Maurizio; Massucci, Maurizio; Bovolenta, Federica; Sale, Patrizio

2013-01-01

Walking ability, though important for quality of life and participation in social and economic activities, can be adversely affected by neurological disorders, such as Spinal Cord Injury, Stroke, Multiple Sclerosis or Traumatic Brain Injury. The aim of this study is to evaluate if the energy cost of walking (CW), in a mixed group of chronic patients with neurological diseases almost 6 months after discharge from rehabilitation wards, can predict the walking performance and any walking restriction on community activities, as indicated by Walking Handicap Scale categories (WHS). One hundred and seven subjects were included in the study, 31 suffering from Stroke, 26 from Spinal Cord Injury and 50 from Multiple Sclerosis. The multivariable binary logistical regression analysis has produced a statistical model with good characteristics of fit and good predictability. This model generated a cut-off value of.40, which enabled us to classify correctly the cases with a percentage of 85.0%. Our research reveal that, in our subjects, CW is the only predictor of the walking performance of in the community, to be compared with the score of WHS. We have been also identifying a cut-off value of CW cost, which makes a distinction between those who can walk in the community and those who cannot do it. In particular, these values could be used to predict the ability to walk in the community when discharged from the rehabilitation units, and to adjust the rehabilitative treatment to improve the performance. PMID:23468871

Locally Weighted Score Estimation for Quantile Classification in Binary Regression Models

PubMed Central

Rice, John D.; Taylor, Jeremy M. G.

2016-01-01

One common use of binary response regression methods is classification based on an arbitrary probability threshold dictated by the particular application. Since this is given to us a priori, it is sensible to incorporate the threshold into our estimation procedure. Specifically, for the linear logistic model, we solve a set of locally weighted score equations, using a kernel-like weight function centered at the threshold. The bandwidth for the weight function is selected by cross validation of a novel hybrid loss function that combines classification error and a continuous measure of divergence between observed and fitted values; other possible cross-validation functions based on more common binary classification metrics are also examined. This work has much in common with robust estimation, but diers from previous approaches in this area in its focus on prediction, specifically classification into high- and low-risk groups. Simulation results are given showing the reduction in error rates that can be obtained with this method when compared with maximum likelihood estimation, especially under certain forms of model misspecification. Analysis of a melanoma data set is presented to illustrate the use of the method in practice. PMID:28018492

Predictive factors for moderate or severe exacerbations in asthma patients receiving outpatient care.

PubMed

Gutiérrez, Francisco Javier Álvarez; Galván, Marta Ferrer; Gallardo, Juan Francisco Medina; Mancera, Marta Barrera; Romero, Beatriz Romero; Falcón, Auxiliadora Romero

2017-05-02

Asthma exacerbations are important events that affect disease control, but predictive factors for severe or moderate exacerbations are not known. The objective was to study the predictive factors for moderate (ME) and severe (SE) exacerbations in asthma patients receiving outpatient care. Patients aged > 12 years with asthma were included in the study and followed-up at 4-monthly intervals over a 12-month period. Clinical (severity, level of control, asthma control test [ACT]), atopic, functional, inflammatory, SE and ME parameters were recorded. Univariate analysis was used to compare data from patients presenting at least 1 SE or ME during the follow-up period vs no exacerbations. Statistically significant (p <0.1) factors were then subjected to multiple analysis by binary logistic regression. A total of 330 patients completed the study, most of whom were atopic (76%), women (nearly 70%), with moderate and mild persistent asthma (>80%). Twenty-seven patients (8%) had a SE and 183 had a ME (58.5%) during follow-up. In the case of SEs, the only predictive factor identified in the multiple analysis was previous SE (baseline visit OR 4.218 95% CI 1.53-11.58, 4-month follow-up OR 6.88 95% CI 2.018-23.51) and inhalation technique (OR 3.572 95% CI 1.324-9.638). In the case of MEs, the only predictive factor found in the multiple analysis were previous ME (baseline visit OR 2.90 95% CI 1.54-5.48, 4-month follow- up OR 1.702 95% CI 1.146-2.529). The primary predictive factor for SE or ME is prior SE or ME, respectively. SEs seem to constitute a specific patient "phenotype", in which the sole predictive factor is prior SEs.

Natural history of multiple sclerosis from the Indian perspective: Experience from a tertiary care hospital.

PubMed

Jena, Subhransu S; Alexander, Mathew; Aaron, Sanjith; Mathew, Vivek; Thomas, Maya Mary; Patil, Anil K; Sivadasan, Ajith; Muthusamy, Karthik; Mani, Sunithi; Rebekah, J Grace

2015-01-01

Multiple sclerosis (MS) has a spectrum of heterogeneity, as seen in western and eastern hemispheres, in the clinical features, topography of involvement and differences in natural history. To study the clinical spectrum, imaging, and electrophysiological as well as cerebrospinal fluid (CSF) characteristics and correlate them with outcome. Retrospective analysis of MS patients during a period of 20 years. Cases were selected according to recent McDonald's criteria (2010), They were managed in the Department of Neurology, Christian Medical College, Vellore. Chi-square and Fisher's exact tests were used for categorical variables. Multiple binary logistic regressions were done to assess significance. Kaplan-Meier curves were drawn to estimate the time to irreversible disability. A total of 157 patients with female preponderance (55%) were included. The inter quartile range duration of follow-up was 9.1 (8.2, 11) years for 114 patients, who were included for final outcome analysis. Relapsing remitting MS (RRMS) (54.1%) was the most common type of MS seen. RRMS had a significantly better outcome (odds ratio: 0.12, 95% confidence interval: 0.02-0.57, P = 0.008) compared to progressive form of MS (primary progressive, secondary progressive). The Expanded Disability Status Scale score of patients at presentation and at final follow-up was 4.4 ± 1.31 and 4.1 ± 2.31, respectively. During the first presentation, polysymptomatic manifestations like motor and sphincteric involvement, incomplete recovery from the first attack; and, during the disease course, bowel, bladder, cerebellar and pyramidal affliction, predicted a worse outcome. A high incidence of optico-spinal presentation, predominance of RRMS and a low yield on cerebrospinal fluid (CSF) studies are the major findings of our study. A notable feature was the analysis of prognostic markers of disability.

Multiplicity of the Galactic Senior Citizens: A High-resolution Search for Cool Subdwarf Companions

NASA Astrophysics Data System (ADS)

Ziegler, Carl; Law, Nicholas M.; Baranec, Christoph; Riddle, Reed L.; Fuchs, Joshua T.

2015-05-01

Cool subdwarfs are the oldest members of the low-mass stellar population. Mostly present in the galactic halo, subdwarfs are characterized by their low-metallicity. Measuring their binary fraction and comparing it to solar-metallicity stars could give key insights into the star formation process early in the Milky Way’s history. However, because of their low luminosity and relative rarity in the solar neighborhood, binarity surveys of cool subdwarfs have suffered from small sample sizes and incompleteness. Previous surveys have suggested that the binary fraction of red subdwarfs is much lower than for their main-sequence cousins. Using the highly efficient Robo-AO system, we present the largest high-resolution survey of subdwarfs, sensitive to angular separations (ρ ≥slant 0.″ 15) and contrast ratios ({Δ }{{m}i} ≤slant 6) invisible in past surveys. Of 344 target cool subdwarfs, 43 are in multiple systems, 19 of which are newly discovered, for a binary fraction of 12.5 ± 1.9%. We also discovered seven triple star systems for a triplet fraction of 2.0 ± 0.8%. Comparisons to similar surveys of solar-metallicity dwarf stars gives a ∼3σ disparity in luminosity between companion stars, with subdwarfs displaying a shortage of low-contrast companions. We also observe a lack of close subdwarf companions in comparison to similar-mass dwarf multiple systems.

Adaptive Digital Signature Design and Short-Data-Record Adaptive Filtering

DTIC Science & Technology

2008-04-01

rate BPSK binary phase shift keying CA − CFAR cell averaging− constant false alarm rate CDMA code − division multiple − access CFAR constant false...Cotae, “Spreading sequence design for multiple cell synchronous DS-CDMA systems under total weighted squared correlation criterion,” EURASIP Journal...415-428, Mar. 2002. [6] P. Cotae, “Spreading sequence design for multiple cell synchronous DS-CDMA systems under total weighted squared correlation

Dynamical Formation Signatures of Black Hole Binaries in the First Detected Mergers by LIGO

NASA Astrophysics Data System (ADS)

O'Leary, Ryan M.; Meiron, Yohai; Kocsis, Bence

2016-06-01

The dynamical formation of stellar-mass black hole-black hole binaries has long been a promising source of gravitational waves for the Laser Interferometer Gravitational-Wave Observatory (LIGO). Mass segregation, gravitational focusing, and multibody dynamical interactions naturally increase the interaction rate between the most massive black holes in dense stellar systems, eventually leading them to merge. We find that dynamical interactions, particularly three-body binary formation, enhance the merger rate of black hole binaries with total mass M tot roughly as \\propto {M}{{tot}}β , with β ≳ 4. We find that this relation holds mostly independently of the initial mass function, but the exact value depends on the degree of mass segregation. The detection rate of such massive black hole binaries is only further enhanced by LIGO’s greater sensitivity to massive black hole binaries with M tot ≲ 80 {M}⊙ . We find that for power-law BH mass functions dN/dM ∝ M -α with α ≤ 2, LIGO is most likely to detect black hole binaries with a mass twice that of the maximum initial black hole mass and a mass ratio near one. Repeated mergers of black holes inside the cluster result in about ˜5% of mergers being observed between two and three times the maximum initial black hole mass. Using these relations, one may be able to invert the observed distribution to the initial mass function with multiple detections of merging black hole binaries.

Sulfide Generated by Sulfate Reduction is a Primary Controller of the Occurrence of Wild Rice (Zizania palustris) in Shallow Aquatic Ecosystems

NASA Astrophysics Data System (ADS)

Myrbo, A.; Swain, E. B.; Engstrom, D. R.; Coleman Wasik, J.; Brenner, J.; Dykhuizen Shore, M.; Peters, E. B.; Blaha, G.

2017-11-01

Field observations suggest that surface water sulfate concentrations control the distribution of wild rice, an aquatic grass (Zizania palustris). However, hydroponic studies show that sulfate is not toxic to wild rice at even unrealistically high concentrations. To determine how sulfate might directly or indirectly affect wild rice, potential wild rice habitat was characterized for 64 chemical and physical variables in over 100 sites spanning a relatively steep climatic and geological gradient in Minnesota. Habitat suitability was assessed by comparing the occurrence of wild rice with the field variables, through binary logistic regression. This analysis demonstrated that sulfide in sediment pore water, generated by the microbial reduction of sulfate that diffuses or advects into the sediment, is the primary control of wild rice occurrence. Water temperature and water transparency independently control the suitability of habitat for wild rice. In addition to generating phytotoxic sulfide, sulfate reduction also supports anaerobic decomposition of organic matter, releasing nutrients that can compound the harm of direct sulfide toxicity. These results are important because they show that increases in sulfate loading to surface water can have multiple negative consequences for ecosystems, even though sulfate itself is relatively benign.

Using machine learning to explore the long-term evolution of GRS 1915+105

NASA Astrophysics Data System (ADS)

Huppenkothen, Daniela; Heil, Lucy M.; Hogg, David W.; Mueller, Andreas

2017-04-01

Among the population of known Galactic black hole X-ray binaries, GRS 1915+105 stands out in multiple ways. It has been in continuous outburst since 1992, and has shown a wide range of different states that can be distinguished by their timing and spectral properties. These states, also observed in IGR J17091-3624, have in the past been linked to accretion dynamics. Here, we present the first comprehensive study into the long-term evolution of GRS 1915+105, using the entire data set observed with Rossi X-ray Timing Explorer over its 16-yr lifetime. We develop a set of descriptive features allowing for automatic separation of states, and show that supervised machine learning in the form of logistic regression and random forests can be used to efficiently classify the entire data set. For the first time, we explore the duty cycle and time evolution of states over the entire 16-yr time span, and find that the temporal distribution of states has likely changed over the span of the observations. We connect the machine classification with physical interpretations of the phenomenology in terms of chaotic and stochastic processes.

School Collective Efficacy and Bullying Behaviour: A Multilevel Study.

PubMed

Olsson, Gabriella; Låftman, Sara Brolin; Modin, Bitte

2017-12-20

As with other forms of violent behaviour, bullying is the result of multiple influences acting on different societal levels. Yet the majority of studies on bullying focus primarily on the characteristics of individual bullies and bullied. Fewer studies have explored how the characteristics of central contexts in young people's lives are related to bullying behaviour over and above the influence of individual-level characteristics. This study explores how teacher-rated school collective efficacy is related to student-reported bullying behaviour (traditional and cyberbullying victimization and perpetration). A central focus is to explore if school collective efficacy is related similarly to both traditional bullying and cyberbullying. Analyses are based on combined information from two independent data collections conducted in 2016 among 11th grade students ( n = 6067) and teachers ( n = 1251) in 58 upper secondary schools in Stockholm. The statistical method used is multilevel modelling, estimating two-level binary logistic regression models. The results demonstrate statistically significant between-school differences in all outcomes, except traditional bullying perpetration. Strong school collective efficacy is related to less traditional bullying perpetration and less cyberbullying victimization and perpetration, indicating that collective norm regulation and school social cohesion may contribute to reducing the occurrence of bullying.

School Collective Efficacy and Bullying Behaviour: A Multilevel Study

PubMed Central

Olsson, Gabriella; Låftman, Sara Brolin; Modin, Bitte

2017-01-01

As with other forms of violent behaviour, bullying is the result of multiple influences acting on different societal levels. Yet the majority of studies on bullying focus primarily on the characteristics of individual bullies and bullied. Fewer studies have explored how the characteristics of central contexts in young people’s lives are related to bullying behaviour over and above the influence of individual-level characteristics. This study explores how teacher-rated school collective efficacy is related to student-reported bullying behaviour (traditional and cyberbullying victimization and perpetration). A central focus is to explore if school collective efficacy is related similarly to both traditional bullying and cyberbullying. Analyses are based on combined information from two independent data collections conducted in 2016 among 11th grade students (n = 6067) and teachers (n = 1251) in 58 upper secondary schools in Stockholm. The statistical method used is multilevel modelling, estimating two-level binary logistic regression models. The results demonstrate statistically significant between-school differences in all outcomes, except traditional bullying perpetration. Strong school collective efficacy is related to less traditional bullying perpetration and less cyberbullying victimization and perpetration, indicating that collective norm regulation and school social cohesion may contribute to reducing the occurrence of bullying. PMID:29261114

Factors associated with self-reported health: implications for ...

EPA Pesticide Factsheets

BACKGROUND: Advocates for environmental justice, local, state, and national public health officials, exposure scientists, need broad-based heath indices to identify vulnerable communities. Longitudinal studies show that perception of current health status predicts subsequent mortality, suggesting that self-reported health (SRH) may be useful in screening-level community assessments. This paper evaluates whether SRH is an appropriate surrogate indicator of health status by evaluating relationships between SRH and sociodemographic, lifestyle, and health care factors as well as serological indicators of nutrition, health risk, and environmental exposures.METHODS: Data were combined from the 2003-2006 National Health and Nutrition Examination Surveys for 1372 nonsmoking 20-50 year olds. Ordinal and binary logistic regression was used to estimate odds ratios and 95 % confidence intervals of reporting poorer health based on measures of nutrition, health condition, environmental contaminants, and sociodemographic, health care, and lifestyle factors.RESULTS: Poorer SRH was associated with several serological measures of nutrition, health condition, and biomarkers of toluene, cadmium, lead, and mercury exposure. Race/ethnicity, income, education, access to health care, food security, exercise, poor mental and physical health, prescription drug use, and multiple health outcome measures (e.g., diabetes, thyroid problems, asthma) were also associated with poorer SRH.CONCLUS

Mobility one week after a hip fracture - can it be predicted?

PubMed

Fitzgerald, Michelle; Blake, Catherine; Askin, David; Quinlan, John; Coughlan, Tara; Cunningham, Caitriona

2018-05-01

Better patient outcomes and more efficient healthcare could be achieved by predicting post hip fracture function at an early stage. This study aimed to identify independent predictors of mobility outcome one week post hip fracture surgery. All hip fracture inpatients (n=77) were included in this 6 month prospective observational cohort study. Predictor variables were obtained on the first postoperative day and included premorbid function using the New Mobility Score (NMS). Mobility outcome measures one week postoperatively included the Cumulated Ambulatory Score (CAS). Data were analysed with SPSS using binary multiple logistic regression analysis RESULTS: Patients who fell outdoors (OR 3.848; 95% CI, 1.053-14.061), had no delay to surgery (OR 5.472; 95% CI, 1.073-27.907) and had high pre-fracture function (OR3.366; 95% CI, 1.042-10.879) were predicted to achieve independent mobility (CAS = 6) one week postoperatively. Fall location, time to surgery and baseline function predict independent mobility one week after hip fracture, and can be used for early rehabilitation stratification. The NMS and CAS are recommended as standardised hip fracture clinical measures. Orthogeriatric and physiotherapy service initiatives may improve early functional outcome. Copyright © 2017. Published by Elsevier Ltd.

Religion and attitudes toward same-sex marriage among U.S. Latinos.

PubMed

Ellison, Christopher G; Acevedo, Gabriel A; Ramos-Wada, Aida I

2011-01-01

Objectives. This study examines links between multiple aspects of religious involvement and attitudes toward same-sex marriage among U.S. Latinos. The primary focus is on variations by affiliation and participation, but the possible mediating roles of biblical beliefs, clergy cues, and the role of religion in shaping political views are also considered.Methods. We use binary logistic regression models to analyze data from a large nationwide sample of U.S. Latinos conducted by the Pew Hispanic Forum in late 2006.Results. Findings highlight the strong opposition to same-sex marriage among Latino evangelical (or conservative) Protestants and members of sectarian groups (e.g., LDS), even compared with devout Catholics. Although each of the hypothesized mediators is significantly linked with attitudes toward same-sex marriage, for the most part controlling for them does not alter the massive affiliation/attendance differences in attitudes toward same-sex marriage.Conclusions. This study illustrates the importance of religious cleavages in public opinion on social issues within the diverse U.S. Latino population. The significance of religious variations in Hispanic civic life is likely to increase with the growth of the Latino population and the rising numbers of Protestants and sectarians among Latinos.

The Rings Around the Egg Nebula

NASA Technical Reports Server (NTRS)

Harpaz, Amos; Rappaport, Saul; Soker, Noam

1997-01-01

We present an eccentric binary model for the formation of the proto-planetary nebula CRL 2688 (the Egg Nebula) that exhibits multiple concentric shells. Given the apparent regularity of the structure in the Egg Nebula, we postulate that the shells are caused by the periodic passages of a companion star. Such an orbital period would have to lie in the range of 100-500 yr, the apparent time that corresponds to the spacing between the rings. We assume, in this model, that an asymptotic giant branch (AGB) star, which is the origin of the matter within the planetary nebula, loses mass in a spherically symmetric wind. We further suppose that the AGB star has an extended atmosphere (out to approximately 10 stellar radii) in which the outflow speed is less than the escape speed; still farther out, grains form and radiation pressure accelerates the grains along with the trapped gas to the escape speed. Once escape speed has been attained, the presence of a companion star will not significantly affect the trajectories of the matter leaving in the wind and the mass loss will be approximately spherically symmetric. On the other hand, if the companion star is sufficiently close that the Roche lobe of the AGB star moves inside the extended atmosphere, then the slowly moving material will be forced to flow approximately along the critical potential surface (i.e., the Roche lobe) until it flows into the potential lobe of the companion star. Therefore, in our model, the shells are caused by periodic cessations of the isotropic wind rather than by any periodic enhancement in the mass-loss process. We carry out detailed binary evolution calculations within the context of this scenario, taking into account the nuclear evolution and stellar wind losses of the giant as well as the effects of mass loss and mass transfer on the evolution of the eccentric binary orbit. From the initial binary parameters that we find are required to produce a multiple concentric shell nebula and the known properties of primordial binaries, we conclude that approximately 0.3% of all planetaries should go through a phase with multiple concentric shells.

Context-Aware Local Binary Feature Learning for Face Recognition.

PubMed

Duan, Yueqi; Lu, Jiwen; Feng, Jianjiang; Zhou, Jie

2018-05-01

In this paper, we propose a context-aware local binary feature learning (CA-LBFL) method for face recognition. Unlike existing learning-based local face descriptors such as discriminant face descriptor (DFD) and compact binary face descriptor (CBFD) which learn each feature code individually, our CA-LBFL exploits the contextual information of adjacent bits by constraining the number of shifts from different binary bits, so that more robust information can be exploited for face representation. Given a face image, we first extract pixel difference vectors (PDV) in local patches, and learn a discriminative mapping in an unsupervised manner to project each pixel difference vector into a context-aware binary vector. Then, we perform clustering on the learned binary codes to construct a codebook, and extract a histogram feature for each face image with the learned codebook as the final representation. In order to exploit local information from different scales, we propose a context-aware local binary multi-scale feature learning (CA-LBMFL) method to jointly learn multiple projection matrices for face representation. To make the proposed methods applicable for heterogeneous face recognition, we present a coupled CA-LBFL (C-CA-LBFL) method and a coupled CA-LBMFL (C-CA-LBMFL) method to reduce the modality gap of corresponding heterogeneous faces in the feature level, respectively. Extensive experimental results on four widely used face datasets clearly show that our methods outperform most state-of-the-art face descriptors.

Very massive runaway stars from three-body encounters

NASA Astrophysics Data System (ADS)

Gvaramadze, Vasilii V.; Gualandris, Alessia

2011-01-01

Very massive stars preferentially reside in the cores of their parent clusters and form binary or multiple systems. We study the role of tight very massive binaries in the origin of the field population of very massive stars. We performed numerical simulations of dynamical encounters between single (massive) stars and a very massive binary with parameters similar to those of the most massive known Galactic binaries, WR 20a and NGC 3603-A1. We found that these three-body encounters could be responsible for the origin of high peculiar velocities (≥70 km s-1) observed for some very massive (≥60-70 M⊙) runaway stars in the Milky Way and the Large Magellanic Cloud (e.g. λ Cep, BD+43°3654, Sk -67°22, BI 237, 30 Dor 016), which can hardly be explained within the framework of the binary-supernova scenario. The production of high-velocity massive stars via three-body encounters is accompanied by the recoil of the binary in the opposite direction to the ejected star. We show that the relative position of the very massive binary R145 and the runaway early B-type star Sk-69°206 on the sky is consistent with the possibility that both objects were ejected from the central cluster, R136, of the star-forming region 30 Doradus via the same dynamical event - a three-body encounter.

The Overall Odds Ratio as an Intuitive Effect Size Index for Multiple Logistic Regression: Examination of Further Refinements

ERIC Educational Resources Information Center

Le, Huy; Marcus, Justin

2012-01-01

This study used Monte Carlo simulation to examine the properties of the overall odds ratio (OOR), which was recently introduced as an index for overall effect size in multiple logistic regression. It was found that the OOR was relatively independent of study base rate and performed better than most commonly used R-square analogs in indexing model…

The KOI 425 Multi-star System

NASA Astrophysics Data System (ADS)

Hughes, Anna; Boley, Aaron C.

2017-10-01

Kepler Object of Interest 425 (KOI 425) is an eclipsing binary with periodic features in addition to the known primary and secondary transits. This KOI has been observed by Saterne et al. 2012 with SOPHIE, who found its phase variance to be indicative of a diluted eclipsing binary, likely produced by a multi-star system. We analyze the complete set of Kepler archival data for this system along with the published SOPHIE results to assess the multiplicity and the dynamics of the system.

Second catalog of interferometric measurements of binary stars (McAlister and Hartkopf 1988): Documentation for the machine-readable version

NASA Technical Reports Server (NTRS)

Warren, Wayne H., Jr.

1989-01-01

The machine-readable version of the catalog, as it is currently being distributed from the Astronomical Data Center, is described. The catalog is a compilation of measurements of binary- and multiple-star systems obtained by speckle interferometric techniques; this version supersedes a previous edition of the catalog published in 1985. Stars that have been examined for multiplicity with negative results are included, in which case upper limits for the separation are given. The second version is expanded from the first in that a file of newly resolved systems and six cross-index files of alternate designations are included. The data file contains alternate identifications for the observed systems, epochs of observation, reported errors in position angles and separation, and bibliographical references.

Logistic random effects regression models: a comparison of statistical packages for binary and ordinal outcomes

PubMed Central

2011-01-01

Background Logistic random effects models are a popular tool to analyze multilevel also called hierarchical data with a binary or ordinal outcome. Here, we aim to compare different statistical software implementations of these models. Methods We used individual patient data from 8509 patients in 231 centers with moderate and severe Traumatic Brain Injury (TBI) enrolled in eight Randomized Controlled Trials (RCTs) and three observational studies. We fitted logistic random effects regression models with the 5-point Glasgow Outcome Scale (GOS) as outcome, both dichotomized as well as ordinal, with center and/or trial as random effects, and as covariates age, motor score, pupil reactivity or trial. We then compared the implementations of frequentist and Bayesian methods to estimate the fixed and random effects. Frequentist approaches included R (lme4), Stata (GLLAMM), SAS (GLIMMIX and NLMIXED), MLwiN ([R]IGLS) and MIXOR, Bayesian approaches included WinBUGS, MLwiN (MCMC), R package MCMCglmm and SAS experimental procedure MCMC. Three data sets (the full data set and two sub-datasets) were analysed using basically two logistic random effects models with either one random effect for the center or two random effects for center and trial. For the ordinal outcome in the full data set also a proportional odds model with a random center effect was fitted. Results The packages gave similar parameter estimates for both the fixed and random effects and for the binary (and ordinal) models for the main study and when based on a relatively large number of level-1 (patient level) data compared to the number of level-2 (hospital level) data. However, when based on relatively sparse data set, i.e. when the numbers of level-1 and level-2 data units were about the same, the frequentist and Bayesian approaches showed somewhat different results. The software implementations differ considerably in flexibility, computation time, and usability. There are also differences in the availability of additional tools for model evaluation, such as diagnostic plots. The experimental SAS (version 9.2) procedure MCMC appeared to be inefficient. Conclusions On relatively large data sets, the different software implementations of logistic random effects regression models produced similar results. Thus, for a large data set there seems to be no explicit preference (of course if there is no preference from a philosophical point of view) for either a frequentist or Bayesian approach (if based on vague priors). The choice for a particular implementation may largely depend on the desired flexibility, and the usability of the package. For small data sets the random effects variances are difficult to estimate. In the frequentist approaches the MLE of this variance was often estimated zero with a standard error that is either zero or could not be determined, while for Bayesian methods the estimates could depend on the chosen "non-informative" prior of the variance parameter. The starting value for the variance parameter may be also critical for the convergence of the Markov chain. PMID:21605357

Vehicle coordinated transportation dispatching model base on multiple crisis locations

NASA Astrophysics Data System (ADS)

Tian, Ran; Li, Shanwei; Yang, Guoying

2018-05-01

Many disastrous events are often caused after unconventional emergencies occur, and the requirements of disasters are often different. It is difficult for a single emergency resource center to satisfy such requirements at the same time. Therefore, how to coordinate the emergency resources stored by multiple emergency resource centers to various disaster sites requires the coordinated transportation of emergency vehicles. In this paper, according to the problem of emergency logistics coordination scheduling, based on the related constraints of emergency logistics transportation, an emergency resource scheduling model based on multiple disasters is established.

Implementing transmission eigenchannels of disordered media by a binary-control digital micromirror device

NASA Astrophysics Data System (ADS)

Kim, Donggyu; Choi, Wonjun; Kim, Moonseok; Moon, Jungho; Seo, Keumyoung; Ju, Sanghyun; Choi, Wonshik

2014-11-01

We report a method for measuring the transmission matrix of a disordered medium using a binary-control of a digital micromirror device (DMD). With knowledge of the measured transmission matrix, we identified the transmission eigenchannels of the medium. We then used binary control of the DMD to shape the wavefront of incident waves and to experimentally couple light to individual eigenchannels. When the wave was coupled to the eigenchannel with the largest eigenvalue, in particular, we were able to achieve about two times more energy transmission than the mean transmittance of the medium. Our study provides an elaborated use of the DMD as a high-speed wavefront shaping device for controlling the multiple scattering of waves in highly scattering media.

On the Possibility of Habitable Trojan Planets in Binary Star Systems.

PubMed

Schwarz, Richard; Funk, Barbara; Bazsó, Ákos

2015-12-01

Approximately 60% of all stars in the solar neighbourhood (up to 80% in our Milky Way) are members of binary or multiple star systems. This fact led to the speculations that many more planets may exist in binary systems than are currently known. To estimate the habitability of exoplanetary systems, we have to define the so-called habitable zone (HZ). The HZ is defined as a region around a star where a planet would receive enough radiation to maintain liquid water on its surface and to be able to build a stable atmosphere. We search for new dynamical configurations-where planets may stay in stable orbits-to increase the probability to find a planet like the Earth.

Multivariate meta-analysis using individual participant data

PubMed Central

Riley, R. D.; Price, M. J.; Jackson, D.; Wardle, M.; Gueyffier, F.; Wang, J.; Staessen, J. A.; White, I. R.

2016-01-01

When combining results across related studies, a multivariate meta-analysis allows the joint synthesis of correlated effect estimates from multiple outcomes. Joint synthesis can improve efficiency over separate univariate syntheses, may reduce selective outcome reporting biases, and enables joint inferences across the outcomes. A common issue is that within-study correlations needed to fit the multivariate model are unknown from published reports. However, provision of individual participant data (IPD) allows them to be calculated directly. Here, we illustrate how to use IPD to estimate within-study correlations, using a joint linear regression for multiple continuous outcomes and bootstrapping methods for binary, survival and mixed outcomes. In a meta-analysis of 10 hypertension trials, we then show how these methods enable multivariate meta-analysis to address novel clinical questions about continuous, survival and binary outcomes; treatment–covariate interactions; adjusted risk/prognostic factor effects; longitudinal data; prognostic and multiparameter models; and multiple treatment comparisons. Both frequentist and Bayesian approaches are applied, with example software code provided to derive within-study correlations and to fit the models. PMID:26099484

A Method for Calculating the Probability of Successfully Completing a Rocket Propulsion Ground Test

NASA Technical Reports Server (NTRS)

Messer, Bradley P.

2004-01-01

Propulsion ground test facilities face the daily challenges of scheduling multiple customers into limited facility space and successfully completing their propulsion test projects. Due to budgetary and schedule constraints, NASA and industry customers are pushing to test more components, for less money, in a shorter period of time. As these new rocket engine component test programs are undertaken, the lack of technology maturity in the test articles, combined with pushing the test facilities capabilities to their limits, tends to lead to an increase in facility breakdowns and unsuccessful tests. Over the last five years Stennis Space Center's propulsion test facilities have performed hundreds of tests, collected thousands of seconds of test data, and broken numerous test facility and test article parts. While various initiatives have been implemented to provide better propulsion test techniques and improve the quality, reliability, and maintainability of goods and parts used in the propulsion test facilities, unexpected failures during testing still occur quite regularly due to the harsh environment in which the propulsion test facilities operate. Previous attempts at modeling the lifecycle of a propulsion component test project have met with little success. Each of the attempts suffered form incomplete or inconsistent data on which to base the models. By focusing on the actual test phase of the tests project rather than the formulation, design or construction phases of the test project, the quality and quantity of available data increases dramatically. A logistic regression model has been developed form the data collected over the last five years, allowing the probability of successfully completing a rocket propulsion component test to be calculated. A logistic regression model is a mathematical modeling approach that can be used to describe the relationship of several independent predictor variables X(sub 1), X(sub 2),..,X(sub k) to a binary or dichotomous dependent variable Y, where Y can only be one of two possible outcomes, in this case Success or Failure. Logistic regression has primarily been used in the fields of epidemiology and biomedical research, but lends itself to many other applications. As indicated the use of logistic regression is not new, however, modeling propulsion ground test facilities using logistic regression is both a new and unique application of the statistical technique. Results from the models provide project managers with insight and confidence into the affectivity of rocket engine component ground test projects. The initial success in modeling rocket propulsion ground test projects clears the way for more complex models to be developed in this area.

Binary Trees and Parallel Scheduling Algorithms.

DTIC Science & Technology

1980-09-01

been pro- cessed for p. time units. If a job does not complete by its due time, it is tardy. In a nonpreemptive schedule, job i is scheduled to process...the preemptive schedule obtained by the algorithm of section 2.1.2 also minimizes 5Ti, this problem is easily solved in parallel. When lci is to e...August 1978, pp. 657-661. 14. Horn, W. A., "Some simple scheduling algorithms," Naval Res. Logist . Qur., Vol. 21, pp. 177-185, 1974. i5. Hforowitz, E

Binary Sequences for Spread-Spectrum Multiple-Access Communication

DTIC Science & Technology

1977-08-01

Massey, J. L., and Uhran, J. J., Jr., "Sub-baud coding," Proceedings of the Thirteenth Annual Allerton Conference on Circuit and System Theory, pp. 539...sequences in a multipl.e access environment," Proceedings of the Thirteenth Annual AIlerton Conference on Circuit and System Theory, pp. 21-27, October...34 Proceedings of the Thirteenth Annual Allertcn Conference on Circuit and System Theory, pp. 548-559, October 1975. Yao, K., *Performance bounds on

Time-series Photometry of the Pre-Main Sequence Binary V4046 Sgr: Testing the Accretion Stream Theory

NASA Astrophysics Data System (ADS)

Tofflemire, Benjamin M.; Mathieu, Robert D.; Ardila, David R.; Ciardi, David R.

2015-01-01

Most stars are born in binaries, and the evolution of protostellar disks in pre-main sequence (PMS) binary stars is a current frontier of star formation research. PMS binary stars can have up to three accretion disks: two circumstellar disks and a circumbinary disk separated by a dynamically cleared gap. Theory suggests that mass may periodically flow in an accretion stream from a circumbinary disk across the gap onto circumstellar disks or stellar surfaces. Thus, accretion in PMS binaries is controlled by not only radiation, disk viscosity, and magnetic fields, but also by orbital dynamics.As part of a larger, ongoing effort to characterize mass accretion in young binary systems, we test the predictions of the binary accretion stream theory through continuous, multi-orbit, multi-color optical and near-infrared (NIR) time-series photometry. Observations such as these are capable of detecting and characterizing these modulated accretion streams, if they are generally present. Broad-band blue and ultraviolet photometry trace the accretion luminosity and photospheric temperature while NIR photometry provide a measurement of warm circumstellar material, all as a function of orbital phase. The predicted phase and magnitude of enhanced accretion are highly dependent on the binary orbital parameters and as such, our campaign focuses on 10 PMS binaries of varying periods and eccentricities. Here we present multi-color optical (U, B,V, R), narrowband (Hα), and multi-color NIR (J, H) lightcurves of the PMS binary V4046 Sgr (P=2.42 days) obtained with the SMARTS 1.3m telescope and LCOGT 1m telescope network. These results act to showcase the quality and breadth of data we have, or are currently obtaining, for each of the PMS binaries in our sample. With the full characterization of our sample, these observations will guide an extension of the accretion paradigm from single young stars to multiple systems.

Terrestrial Planet Formation in Binary Star Systems

NASA Technical Reports Server (NTRS)

Lissauer, J. J.; Quintana, E. V.; Adams, F. C.; Chambers, J. E.

2006-01-01

Most stars reside in binary/multiple star systems; however, previous models of planet formation have studied growth of bodies orbiting an isolated single star. Disk material has been observed around one or both components of various young close binary star systems. If planets form at the right places within such disks, they can remain dynamically stable for very long times. We have simulated the late stages of growth of terrestrial planets in both circumbinary disks around 'close' binary star systems with stellar separations ($a_B$) in the range 0.05 AU $\\le a_B \\le$ 0.4 AU and binary eccentricities in the range $0 \\le e \\le 0.8$ and circumstellar disks around individual stars with binary separations of tens of AU. The initial disk of planetary embryos is the same as that used for simulating the late stages of terrestrial planet growth within our Solar System and around individual stars in the Alpha Centauri system (Quintana et al. 2002, A.J., 576, 982); giant planets analogous to Jupiter and Saturn are included if their orbits are stable. The planetary systems formed around close binaries with stellar apastron distances less than or equal to 0.2 AU with small stellar eccentricities are very similar to those formed in the Sun-Jupiter-Saturn, whereas planetary systems formed around binaries with larger maximum separations tend to be sparser, with fewer planets, especially interior to 1 AU. Likewise, when the binary periastron exceeds 10 AU, terrestrial planets can form over essentially the entire range of orbits allowed for single stars with Jupiter-like planets, although fewer terrestrial planets tend to form within high eccentricity binary systems. As the binary periastron decreases, the radial extent of the terrestrial planet systems is reduced accordingly. When the periastron is 5 AU, the formation of Earth-like planets near 1 AU is compromised.

Binary adsorption of copper(II) and cadmium(II) from aqueous solutions by biomass of marine alga Durvillaea potatorum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Q.; Kaewsarn, P.

1999-06-01

Much work on the biosorption of heavy metals by low-cost, natural biomass has been on the uptake of single metals. In practice, wastewaters often contain multiple heavy metal ions. In this paper the binary adsorption of copper(II) and cadmium(II) by a pretreated biomass of the marine alga Durvillaea potatorum from aqueous solutions was studied. The results showed that the uptake capacities for each heavy metal of the binary system were lower when compared with the single metal biosorption for copper and cadmium, respectively, but the total capacities for the binary system were similar to those obtained for single metal biosorption.more » The uptake capacities for copper and cadmium increased as the equilibrium pH increased and reached a plateau at a pH around 5.0. The uptake process was relatively fast, with 90% of the adsorption completed within 10 minutes for copper and 30 minutes for cadmium, and equilibrium reached after about 60 minutes of stirring. The biosorption isotherms of binary systems were not significantly affected by equilibrium temperature. The presence of light metal ions in solution also did not affect adsorption significantly. The binary adsorption was successfully predicted by the extended Langmuir model, using parameters and capacities obtained from single component systems.« less

THE SOLAR NEIGHBORHOOD. XXVIII. THE MULTIPLICITY FRACTION OF NEARBY STARS FROM 5 TO 70 AU AND THE BROWN DWARF DESERT AROUND M DWARFS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dieterich, Sergio B.; Henry, Todd J.; Golimowski, David A.

2012-08-15

We report on our analysis of Hubble Space Telescope/NICMOS snapshot high-resolution images of 255 stars in 201 systems within {approx}10 pc of the Sun. Photometry was obtained through filters F110W, F180M, F207M, and F222M using NICMOS Camera 2. These filters were selected to permit clear identification of cool brown dwarfs through methane contrast imaging. With a plate scale of 76 mas pixel{sup -1}, NICMOS can easily resolve binaries with subarcsecond separations in the 19.''5 Multiplication-Sign 19.''5 field of view. We previously reported five companions to nearby M and L dwarfs from this search. No new companions were discovered during themore » second phase of data analysis presented here, confirming that stellar/substellar binaries are rare. We establish magnitude and separation limits for which companions can be ruled out for each star in the sample, and then perform a comprehensive sensitivity and completeness analysis for the subsample of 138 M dwarfs in 126 systems. We calculate a multiplicity fraction of 0.0{sup +3.5}{sub -0.0}% for L companions to M dwarfs in the separation range of 5-70 AU, and 2.3{sup +5.0}{sub -0.7}% for L and T companions to M dwarfs in the separation range of 10-70 AU. We also discuss trends in the color-magnitude diagrams using various color combinations and present astrometry for 19 multiple systems in our sample. Considering these results and results from several other studies, we argue that the so-called brown dwarf desert extends to binary systems with low-mass primaries and is largely independent of primary mass, mass ratio, and separations. While focusing on companion properties, we discuss how the qualitative agreement between observed companion mass functions and initial mass functions suggests that the paucity of brown dwarfs in either population may be due to a common cause and not due to binary formation mechanisms.« less

Characterization of serum microRNAs profile of PCOS and identification of novel non-invasive biomarkers.

PubMed

Long, Wei; Zhao, Chun; Ji, Chenbo; Ding, Hongjuan; Cui, Yugui; Guo, Xirong; Shen, Rong; Liu, Jiayin

2014-01-01

Polycystic ovary syndrome (PCOS), the most common endocrinopathy in women of reproductive age, is characterized by polycystic ovaries, chronic anovulation, hyperandrogenism and insulin resistance. Despite the high prevalence of hyperandrogenemia, a definitive endocrine marker for PCOS has so far not been identified. Circulating miRNAs have recently been shown to serve as diagnostic/prognostic biomarkers in patients with cancers. Our current study focused on the altered expression of serum miRNAs and their correlation with PCOS. We systematically used the TaqMan Low Density Array followed by individual quantitative reverse transcription polymerase chain reaction assays to identify and validate the expression of serum miRNAs of PCOS patients. The expression levels of three miRNAs (miR-222, miR-146a and miR-30c) were significantly increased in PCOS patients with respect to the controls in our discovery evaluation and followed validation. The area under the receiver operating characteristic (ROC) curve (AUC) is 0.799, 0.706, and 0.688, respectively. The combination of the three miRNAs using multiple logistic regression analysis showed a larger AUC (0.852) that was more efficient for the diagnosis of PCOS. In addition, logistic binary regression analyses show miR-222 is positively associated with serum insulin, while miR-146a is negatively associated with serum testosterone. Furthermore, bioinformatics analysis indicated that the predicted targets function of the three miRNAs mainly involved in the metastasis, cell cycle, apoptosis and endocrine. Serum miRNAs are differentially expressed between PCOS patients and controls. We identified and validated a class of three serum miRNAs that could act as novel non-invasive biomarkers for diagnosis of PCOS. These miRNAs may be involved in the pathogenesis of PCOS. © 2014 S. Karger AG, Basel.

Predictors of hazardous drinking, tobacco smoking and physical inactivity in vocational school students

PubMed Central

2013-01-01

Background Tobacco smoking, hazardous drinking and physical inactivity during adolescence are risk factors that are associated with poorer health in adulthood. The identification of subgroups of young people with a high prevalence of one or more of these risk factors allows an optimised allocation of preventive measures. This study aimed at investigating hazardous drinking, tobacco smoking and physical inactivity as well as their associations and demographic predictors in vocational school students. Methods Out of 57 contacted vocational schools in Switzerland, a total of 24 schools participated in a survey assessing gender, age, immigrant background, educational attainment and vocational field as well as the above mentioned health risk factors. Out of the 2659 students present in 177 included vocational school classes, 2647 (99.5%) completed the survey. Binary logistic regression analyses were conducted to investigate the demographic predictors of each health risk factor and a multinomial logistic regression analysis was conducted to investigate predictors of different risk factor combinations. Results Of the surveyed students, 79.4% showed at least one risk factor, 43.6% showed two or more and 9.6% showed all three health risk factors. Hazardous drinking was more prevalent in male, physical inactivity was more prevalent in female vocational school students. The proportion of students with low physical activity and tobacco smoking increased with increasing age. While the combination of hazardous drinking and tobacco smoking was higher in males, the other risk factor combinations were observed particularly among females. Conclusions Multiple risk factors were ascertained in a significant proportion of vocational school students. Specifically, tobacco smoking and hazardous drinking were coexistent. The study underlines the need for preventive measures in specific subpopulations of adolescents and young adults with lower educational level. PMID:23672294

Sequence analysis to assess labour market participation following vocational rehabilitation: an observational study among patients sick-listed with low back pain from a randomised clinical trial in Denmark.

PubMed

Lindholdt, Louise; Labriola, Merete; Nielsen, Claus Vinther; Horsbøl, Trine Allerslev; Lund, Thomas

2017-07-20

The return-to-work (RTW) process after long-term sickness absence is often complex and long and implies multiple shifts between different labour market states for the absentee. Standard methods for examining RTW research typically rely on the analysis of one outcome measure at a time, which will not capture the many possible states and transitions the absentee can go through. The purpose of this study was to explore the potential added value of sequence analysis in supplement to standard regression analysis of a multidisciplinary RTW intervention among patients with low back pain (LBP). The study population consisted of 160 patients randomly allocated to either a hospital-based brief or a multidisciplinary intervention. Data on labour market participation following intervention were obtained from a national register and analysed in two ways: as a binary outcome expressed as active or passive relief at a 1-year follow-up and as four different categories for labour market participation. Logistic regression and sequence analysis were performed. The logistic regression analysis showed no difference in labour market participation for patients in the two groups after 1 year. Applying sequence analysis showed differences in subsequent labour market participation after 2 years after baseline in favour of the brief intervention group versus the multidisciplinary intervention group. The study indicated that sequence analysis could provide added analytical value as a supplement to traditional regression analysis in prospective studies of RTW among patients with LBP. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

High FIB-4 index as an independent risk factor of prevalent chronic kidney disease in patients with nonalcoholic fatty liver disease.

PubMed

Xu, Huang-Wei; Hsu, Yung-Chien; Chang, Chia-Hao; Wei, Kuo-Liang; Lin, Chun-Liang

2016-03-01

Growing evidence suggests that non-alcoholic fatty liver disease (NAFLD) is linked to an increased risk for chronic kidney disease (CKD); liver fibrosis with biopsy-proven NAFLD has also been shown to associate with an increased risk of CKD. This study compares the diagnostic performance of simple noninvasive tests in identifying prevalent CKD among individuals with ultrasonography-diagnosed NAFLD. A total of 755 with ultrasonography-diagnosed NAFLD were included. Estimated glomerular filtration rate and noninvasive markers for hepatic fibrosis: aspartate transaminase to alanine transaminase ratio (AAR), aspartate transaminase to platelet ratio index (APRI), FIB-4 score, NAFLD fibrosis score (NFS) and BARD score were assessed. Binary logistic regression to generate a propensity score and receiver operating characteristic curves were developed for each of the noninvasive markers for predicting CKD, and the area under the receiver operating characteristic curve was greatest for FIB-4 score (0.750), followed by NFS (0.710), AAR (0.594), APRI (0.587), and BARD score (0.561). A cut-off value of 1.100 for FIB-4 score gave a sensitivity of 68.85% and a specificity of 71.07% for predicting CKD. The positive predictive value and negative predictive value were 37.50 and 90.05%, respectively. In multiple logistic regression analysis, only FIB-4 score ≧1.100 (OR 2.660, 95% CI 1.201-5.889; p = .016), older age, higher diastolic blood pressure and higher uric acid were independent predictors of CKD. High noninvasive fibrosis score is associated with an increased risk of prevalent CKD; the FIB-4 is the better predictor. With a cut-off value of 1.100 for FIB-4, it is useful in excluding the presence of CKD in patients with NAFLD.

One size does not fit all: an examination of low birthweight disparities among a diverse set of racial/ethnic groups.

PubMed

Johnelle Sparks, P

2009-11-01

To examine disparities in low birthweight using a diverse set of racial/ethnic categories and a nationally representative sample. This research explored the degree to which sociodemographic characteristics, health care access, maternal health status, and health behaviors influence birthweight disparities among seven racial/ethnic groups. Binary logistic regression models were estimated using a nationally representative sample of singleton, normal for gestational age births from 2001 using the ECLS-B, which has an approximate sample size of 7,800 infants. The multiple variable models examine disparities in low birthweight (LBW) for seven racial/ethnic groups, including non-Hispanic white, non-Hispanic black, U.S.-born Mexican-origin Hispanic, foreign-born Mexican-origin Hispanic, other Hispanic, Native American, and Asian mothers. Race-stratified logistic regression models were also examined. In the full sample models, only non-Hispanic black mothers have a LBW disadvantage compared to non-Hispanic white mothers. Maternal WIC usage was protective against LBW in the full models. No prenatal care and adequate plus prenatal care increase the odds of LBW. In the race-stratified models, prenatal care adequacy and high maternal health risks are the only variables that influence LBW for all racial/ethnic groups. The race-stratified models highlight the different mechanism important across the racial/ethnic groups in determining LBW. Differences in the distribution of maternal sociodemographic, health care access, health status, and behavior characteristics by race/ethnicity demonstrate that a single empirical framework may distort associations with LBW for certain racial and ethnic groups. More attention must be given to the specific mechanisms linking maternal risk factors to poor birth outcomes for specific racial/ethnic groups.

The Orion Bullets: New GEMS MCAO images

NASA Astrophysics Data System (ADS)

Ginsburg, Adam; Bally, John; Youngblood, Allison

2013-07-01

The Orion A molecular cloud (OMC1) is the nearest site of massive star formation at a distance of 414 pc. The BN/KL region within it contains signs of a massive explosion triggered 500 years ago by decay of a non- hierarchical multiple system of massive stars. We present observations of the OMC1 core at high spatial resolution (<0.1") in narrow-band [Fe II] 1.64um and H2 S(1) 1-0 2.12um filters. The new data reveal compact (0.1" to 0.5") knots with unique excitation and chemical properties, unveiling new details about the three-dimensional structure of the explosion. Bright H2 emission from these compact, high proper-motion knots and compact [Fe II] features are consistent with scenario proposed by Bally et al. (2011) in which they are interpreted to be high density (n > 10^8 cm^{-3}) disk fragments launched from within a few AU of a massive star by a > three-body dynamical interaction that led to the ejection of the BN objects and the formation of a compact (separation < few AU) binary, most likely radio source I. The proper motions are as high as 400 km/s, hinting at the enormous energy unleashed in the explosion. The data also unveiled a population of obscured close binary systems. This new population will allow a comparison of embedded young binary systems with the older, un-obscured, visual binary population to test models of the evolution of multiplicity statistics in the Orion Nebula Cluster.

Radial Velocity Studies of Close Binary Stars. XI.

NASA Astrophysics Data System (ADS)

Pribulla, Theodor; Rucinski, Slavek M.; Lu, Wenxian; Mochnacki, Stefan W.; Conidis, George; Blake, R. M.; DeBond, Heide; Thomson, J. R.; Pych, Wojtek; Ogłoza, Waldemar; Siwak, Michal

2006-08-01

Radial-velocity measurements and sine-curve fits to orbital radial velocity variations are presented for 10 close binary systems: DU Boo, ET Boo, TX Cnc, V1073 Cyg, HL Dra, AK Her, VW LMi, V566 Oph, TV UMi, and AG Vir. With this contribution, the David Dunlap Observatory program has reached the point of 100 published radial velocity orbits. The radial velocities have been determined using an improved fitting technique that uses rotational profiles to approximate individual peaks in broadening functions. Three systems, ET Boo, VW LMi, and TV UMi, are found to be quadruple, while AG Vir appears to be a spectroscopic triple. ET Boo, a member of a close visual binary with Pvis=113 yr, was previously known to be a multiple system, but we show that the second component is actually a close, noneclipsing binary. The new observations have enabled us to determine the spectroscopic orbits of the companion, noneclipsing pairs in ET Boo and VW LMi. A particularly interesting case is VW LMi, for which the period of the mutual revolution of the two spectroscopic binaries is only 355 days. While most of the studied eclipsing pairs are contact binaries, ET Boo is composed of two double-lined detached binaries, and HL Dra is a single-lined detached or semidetached system. Five systems of this group have been observed spectroscopically before: TX Cnc, V1073 Cyg, AK Her (as a single-lined binary), V566 Oph, and AG Vir, but our new data are of much higher quality than in the previous studies. Based on data obtained at the David Dunlap Observatory, University of Toronto, Canada.

Spectroscopic binaries in the Solar Twin Planet Search program: from substellar-mass to M dwarf companions

NASA Astrophysics Data System (ADS)

dos Santos, Leonardo A.; Meléndez, Jorge; Bedell, Megan; Bean, Jacob L.; Spina, Lorenzo; Alves-Brito, Alan; Dreizler, Stefan; Ramírez, Iván; Asplund, Martin

2017-12-01

Previous studies on the rotation of Sun-like stars revealed that the rotational rates of young stars converge towards a well-defined evolution that follows a power-law decay. It seems, however, that some binary stars do not obey this relation, often by displaying enhanced rotational rates and activity. In the Solar Twin Planet Search program, we observed several solar twin binaries, and found a multiplicity fraction of 42 per cent ± 6 per cent in the whole sample; moreover, at least three of these binaries (HIP 19911, HIP 67620 and HIP 103983) clearly exhibit the aforementioned anomalies. We investigated the configuration of the binaries in the program, and discovered new companions for HIP 6407, HIP 54582, HIP 62039 and HIP 30037, of which the latter is orbited by a 0.06 M⊙ brown dwarf in a 1 m long orbit. We report the orbital parameters of the systems with well-sampled orbits and, in addition, the lower limits of parameters for the companions that only display a curvature in their radial velocities. For the linear trend binaries, we report an estimate of the masses of their companions when their observed separation is available, and a minimum mass otherwise. We conclude that solar twin binaries with low-mass stellar companions at moderate orbital periods do not display signs of a distinct rotational evolution when compared to single stars. We confirm that the three peculiar stars are double-lined binaries, and that their companions are polluting their spectra, which explains the observed anomalies.

Invited Article: Mask-modulated lensless imaging with multi-angle illuminations

NASA Astrophysics Data System (ADS)

Zhang, Zibang; Zhou, You; Jiang, Shaowei; Guo, Kaikai; Hoshino, Kazunori; Zhong, Jingang; Suo, Jinli; Dai, Qionghai; Zheng, Guoan

2018-06-01

The use of multiple diverse measurements can make lensless phase retrieval more robust. Conventional diversity functions include aperture diversity, wavelength diversity, translational diversity, and defocus diversity. Here we discuss a lensless imaging scheme that employs multiple spherical-wave illuminations from a light-emitting diode array as diversity functions. In this scheme, we place a binary mask between the sample and the detector for imposing support constraints for the phase retrieval process. This support constraint enforces the light field to be zero at certain locations and is similar to the aperture constraint in Fourier ptychographic microscopy. We use a self-calibration algorithm to correct the misalignment of the binary mask. The efficacy of the proposed scheme is first demonstrated by simulations where we evaluate the reconstruction quality using mean square error and structural similarity index. The scheme is then experimentally tested by recovering images of a resolution target and biological samples. The proposed scheme may provide new insights for developing compact and large field-of-view lensless imaging platforms. The use of the binary mask can also be combined with other diversity functions for better constraining the phase retrieval solution space. We provide the open-source implementation code for the broad research community.

CHANDRA OBSERVATIONS OF GALAXY ZOO MERGERS: FREQUENCY OF BINARY ACTIVE NUCLEI IN MASSIVE MERGERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teng, Stacy H.; Schawinski, Kevin; Urry, C. Megan

We present the results from a Chandra pilot study of 12 massive galaxy mergers selected from Galaxy Zoo. The sample includes major mergers down to a host galaxy mass of 10{sup 11} M{sub Sun} that already have optical active galactic nucleus (AGN) signatures in at least one of the progenitors. We find that the coincidences of optically selected active nuclei with mildly obscured (N{sub H} {approx}< 1.1 Multiplication-Sign 10{sup 22} cm{sup -2}) X-ray nuclei are relatively common (8/12), but the detections are too faint (<40 counts per nucleus; f{sub 2-10keV} {approx}< 1.2 Multiplication-Sign 10{sup -13} erg s{sup -1} cm{sup -2})more » to reliably separate starburst and nuclear activity as the origin of the X-ray emission. Only one merger is found to have confirmed binary X-ray nuclei, though the X-ray emission from its southern nucleus could be due solely to star formation. Thus, the occurrences of binary AGNs in these mergers are rare (0%-8%), unless most merger-induced active nuclei are very heavily obscured or Compton thick.« less

The Multiplicity of Wolf-Rayet Stars

NASA Technical Reports Server (NTRS)

Wallace, Debra J.

2004-01-01

The most massive stars drastically reconfigure their surroundings via their strong stellar winds and powerful ionizing radiation. With this mass fueling their large luminosities, these stars are frequently used as standard candles in distance determination, and as tracers of stellar evolution in different regions and epochs. In their dieing burst, some of the once massive stars will enter a Wolf-Rayet (WR) phase lasting approx.10% of the stellar lifetime. This phase is particularly useful for study because these stars have strong spectroscopic signatures that allow them to be easily identified at great distances. But how accurate are these identifications? Increasingly, the relatively nearby stars we once assumed to be single are revealing themselves to be binary or multiple. New techniques, such as high-resolution imaging and interferometry, are changing our knowledge of these objects. I will discuss recent results in the literature and how this affects the binary distribution of WR stars. I will also discuss the implications of binary vs. single star evolution on evolution through the WR phase. Finally, I will discuss the implications of these revised numbers on both massive stellar evolution itself, and the impact that this has on the role of WR stars as calibrators.

Exploring the Effects of Stellar Multiplicity on Exoplanet Occurrence Rates

NASA Astrophysics Data System (ADS)

Barclay, Thomas; Shabram, Megan

2017-06-01

Determining the frequency of habitable worlds is a key goal of the Kepler mission. During Kepler's four year investigation it detected thousands of transiting exoplanets with sizes varying from smaller than Mercury to larger than Jupiter. Finding planets was just the first step to determining frequency, and for the past few years the mission team has been modeling the reliability and completeness of the Kepler planet sample. One effect that has not typically been built into occurrence rate statistics is that of stellar multiplicity. If a planet orbits the primary star in a binary or triple star system then the transit depth will be somewhat diluted resulting in a modest underestimation in the planet size. However, if a detected planet orbits a fainter star then the error in measured planet radius can be very significant. We have taken a hypothetical star and planet population and passed that through a Kepler detection model. From this we have derived completeness corrections for a realistic case of a Universe with binary stars and compared that with a model Universe where all stars are single. We report on the impact that binaries have on exoplanet population statistics.

Imprints of dynamical interactions on brown dwarf pairing statistics and kinematics

NASA Astrophysics Data System (ADS)

Sterzik, M. F.; Durisen, R. H.

2003-03-01

We present statistically robust predictions of brown dwarf properties arising from dynamical interactions during their early evolution in small clusters. Our conclusions are based on numerical calculations of the internal cluster dynamics as well as on Monte-Carlo models. Accounting for recent observational constraints on the sub-stellar mass function and initial properties in fragmenting star forming clumps, we derive multiplicity fractions, mass ratios, separation distributions, and velocity dispersions. We compare them with observations of brown dwarfs in the field and in young clusters. Observed brown dwarf companion fractions around 15 +/- 7% for very low-mass stars as reported recently by Close et al. (\\cite{CSFB03}) are consistent with certain dynamical decay models. A significantly smaller mean separation distribution for brown dwarf binaries than for binaries of late-type stars can be explained by similar specific energy at the time of cluster formation for all cluster masses. Due to their higher velocity dispersions, brown-dwarfs and low-mass single stars will undergo time-dependent spatial segregation from higher-mass stars and multiple systems. This will cause mass functions and binary statistics in star forming regions to vary with the age of the region and the volume sampled.

A new phase encoding approach for a compact head-up display

NASA Astrophysics Data System (ADS)

Suszek, Jaroslaw; Makowski, Michal; Sypek, Maciej; Siemion, Andrzej; Kolodziejczyk, Andrzej; Bartosz, Andrzej

2008-12-01

The possibility of encoding multiple asymmetric symbols into a single thin binary Fourier hologram would have a practical application in the design of simple translucent holographic head-up displays. A Fourier hologram displays the encoded images at the infinity so this enables an observation without a time-consuming eye accommodation. Presenting a set of the most crucial signs for a driver in this way is desired, especially by older people with various eyesight disabilities. In this paper a method of holographic design is presented that assumes a combination of a spatial segmentation and carrier frequencies. It allows to achieve multiple reconstructed images selectable by the angle of the incident laser beam. In order to encode several binary symbols into a single Fourier hologram, the chessboard shaped segmentation function is used. An optimized sequence of phase encoding steps and a final direct phase binarization enables recording of asymmetric symbols into a binary hologram. The theoretical analysis is presented, verified numerically and confirmed in the optical experiment. We suggest and describe a practical and highly useful application of such holograms in an inexpensive HUD device for the use of the automotive industry. We present two alternative propositions of car viewing setups.

Analysis of the multiple system with chemically peculiar component φ Draconis

NASA Astrophysics Data System (ADS)

Liška, J.

2016-09-01

The star ϕ Dra comprises a spectroscopic binary and a third star that together form a visual triple system. It is one of the brightest chemically peculiar stars of the upper main sequence. Despite these facts, no comprehensive study of its multiplicity has been performed yet. In this work, we present a detailed analysis of the triple system based on available measurements. We use radial velocities taken from four sources in the literature in a re-analysis of the inner spectroscopic binary (Aab). An incorrect value of the orbital period of the inner system Aab about 27 d was accepted in literature more than 40 yr. A new solution of orbit with the 128-d period was determined. Relative position measurements of the outer visual binary system (AB) from Washington Double Star Catalog were compared with known orbital models. Furthermore, it was shown that astrometric motion in system AB is well described by the model of Andrade with a 308-yr orbital period. Parameters of A and B components were utilized to estimate individual brightness for all components and their masses from evolutionary tracks. Although we found several facts which support the gravitational bond between them, unbound solution cannot be fully excluded yet.

An Experimental Realization of a Chaos-Based Secure Communication Using Arduino Microcontrollers

PubMed Central

Zapateiro De la Hoz, Mauricio; Vidal, Yolanda

2015-01-01

Security and secrecy are some of the important concerns in the communications world. In the last years, several encryption techniques have been proposed in order to improve the secrecy of the information transmitted. Chaos-based encryption techniques are being widely studied as part of the problem because of the highly unpredictable and random-look nature of the chaotic signals. In this paper we propose a digital-based communication system that uses the logistic map which is a mathematically simple model that is chaotic under certain conditions. The input message signal is modulated using a simple Delta modulator and encrypted using a logistic map. The key signal is also encrypted using the same logistic map with different initial conditions. In the receiver side, the binary-coded message is decrypted using the encrypted key signal that is sent through one of the communication channels. The proposed scheme is experimentally tested using Arduino shields which are simple yet powerful development kits that allows for the implementation of the communication system for testing purposes. PMID:26413563

Discovery of wide low and very low-mass binary systems using Virtual Observatory tools

NASA Astrophysics Data System (ADS)

Gálvez-Ortiz, M. C.; Solano, E.; Lodieu, N.; Aberasturi, M.

2017-04-01

The frequency of multiple systems and their properties are key constraints of stellar formation and evolution. Formation mechanisms of very low-mass (VLM) objects are still under considerable debate, and an accurate assessment of their multiplicity and orbital properties is essential for constraining current theoretical models. Taking advantage of the virtual observatory capabilities, we looked for comoving low and VLM binary (or multiple) systems using the Large Area Survey of the UKIDSS LAS DR10, SDSS DR9 and the 2MASS Catalogues. Other catalogues (WISE, GLIMPSE, SuperCosmos, etc.) were used to derive the physical parameters of the systems. We report the identification of 36 low and VLM (˜M0-L0 spectral types) candidates to binary/multiple system (separations between 200 and 92 000 au), whose physical association is confirmed through common proper motion, distance and low probability of chance alignment. This new system list notably increases the previous sampling in their mass-separation parameter space (˜100). We have also found 50 low-mass objects that we can classify as ˜L0-T2 according to their photometric information. Only one of these objects presents a common proper motion high-mass companion. Although we could not constrain the age of the majority of the candidates, probably most of them are still bound except four that may be under disruption processes. We suggest that our sample could be divided in two populations: one tightly bound wide VLM systems that are expected to last more than 10 Gyr, and other formed by weak bound wide VLM systems that will dissipate within a few Gyr.

A Multiplicity Census of Young Stars in Chamaeleon I

NASA Astrophysics Data System (ADS)

Lafrenière, David; Jayawardhana, Ray; Brandeker, Alexis; Ahmic, Mirza; van Kerkwijk, Marten H.

2008-08-01

We present the results of a multiplicity survey of 126 stars spanning ~0.1-3 M⊙ in the ~2 Myr old Chamaeleon I star-forming region, based on adaptive optics imaging with the ESO Very Large Telescope. Our observations have revealed 30 binaries and six triples, of which 19 and four, respectively, are new discoveries. The overall multiplicity fraction we find for Cha I (~30%) is similar to those reported for other dispersed young associations, but significantly higher than seen in denser clusters and the field, for comparable samples. Both the frequency and the maximum separation of Cha I binaries decline with decreasing mass, while the mass ratios approach unity; conversely, tighter pairs are more likely to be equal mass. We confirm that brown dwarf companions to stars are rare, even at young ages at wide separations. Based on follow-up spectroscopy of two low-mass substellar companion candidates, we conclude that both are likely background stars. The overall multiplicity fraction in Cha I is in rough agreement with numerical simulations of cloud collapse and fragmentation, but its observed mass dependence is less steep than predicted. The paucity of higher order multiples, in particular, provides a stringent constraint on the simulations, and seems to indicate a low level of turbulence in the prestellar cores in Cha I.

Efficient Residue to Binary Conversion Based on a Modified Flexible Moduli Set

NASA Astrophysics Data System (ADS)

Molahosseini, Amir Sabbagh

2011-09-01

The Residue Number System (RNS) is a non-weighted number system which can perform addition (subtraction) and multiplication on residues without carry-propagation; resulting in high-speed hardware implementations of computation systems. The problem of converting residue numbers to equivalent binary weighted form has been attracted a lot of research for many years. Recently, some researchers proposed using flexible moduli sets instead of previous traditional moduli sets to enhance the performance of residue to binary converters. This paper introduces the modified flexible moduli set {22p+k. 22p+1, 2p+1, 2p-1} which is achieved from the flexible set {2p+k, 22p+1, 2p+1, 2p-1} by enhancing modulo 2p+k. Next, new Chinese remainder theorem-1 is used to design simple and efficient residue to binary converter for this modified set with better performance than the converter of the moduli set {2p+k, 22p+1, 2p+1, 2p-1}.

Time Series Observations of the 2015 Eclipse of b Persei (not beta Persei) (Abstract)

NASA Astrophysics Data System (ADS)

Collins, D. F.

2016-06-01

(Abstract only) The bright (V = 4.6) ellipsoidal variable b Persei consists of a close non-eclipsing binary pair that shows a nearly sinusoidal light curve with a ~1.5 day period. This system also contains a third star that orbits the binary pair every 702 days. AAVSO observers recently detected the first ever optical eclipse of A-B binary pair by the third star as a series of snapshots (D. Collins, R. Zavala, J. Sanborn - AAVSO Spring Meeting, 2013); abstract published in Collins, JAAVSO, 41, 2, 391 (2013); b Per mis-printed as b Per therein. A follow-up eclipse campaign in mid-January 2015 recorded time-series observations. These new time-series observations clearly show multiple ingress and egress of each component of the binary system by the third star over the eclipse duration of 2 to 3 days. A simulation of the eclipse was created. Orbital and some astrophysical parameters were adjusted within constraints to give a reasonable fit to the observed light curve.

Tidally Induced Pulsations in Kepler Eclipsing Binary KIC 3230227

NASA Astrophysics Data System (ADS)

Guo, Zhao; Gies, Douglas R.; Fuller, Jim

2017-01-01

KIC 3230227 is a short period (P ≈ 7.0 days) eclipsing binary with a very eccentric orbit (e = 0.6). From combined analysis of radial velocities and Kepler light curves, this system is found to be composed of two A-type stars, with masses of M1 = 1.84 ± 0.18 M⊙, M2 = 1.73 ± 0.17 M⊙ and radii of R1 = 2.01 ± 0.09 R⊙, R2 = 1.68 ± 0.08 R⊙ for the primary and secondary, respectively. In addition to an eclipse, the binary light curve shows a brightening and dimming near periastron, making this a somewhat rare eclipsing heartbeat star system. After removing the binary light curve model, more than 10 pulsational frequencies are present in the Fourier spectrum of the residuals, and most of them are integer multiples of the orbital frequency. These pulsations are tidally driven, and both the amplitudes and phases are in agreement with predictions from linear tidal theory for l = 2, m = -2 prograde modes.

Episodic accretion in binary protostars emerging from self-gravitating solar mass cores

NASA Astrophysics Data System (ADS)

Riaz, R.; Vanaverbeke, S.; Schleicher, D. R. G.

2018-06-01

Observations show a large spread in the luminosities of young protostars, which are frequently explained in the context of episodic accretion. We tested this scenario with numerical simulations that follow the collapse of a solar mass molecular cloud using the GRADSPH code, thereby varying the strength of the initial perturbations and temperature of the cores. A specific emphasis of this paper is to investigate the role of binaries and multiple systems in the context of episodic accretion and to compare their evolution to the evolution in isolated fragments. Our models form a variety of low-mass protostellar objects including single, binary, and triple systems in which binaries are more active in exhibiting episodic accretion than isolated protostars. We also find a general decreasing trend in the average mass accretion rate over time, suggesting that the majority of the protostellar mass is accreted within the first 105 years. This result can potentially help to explain the surprisingly low average luminosities in the majority of the protostellar population.

A Loader for Executing Multi-Binary Applications on the Thinking Machines CM-5: It's Not Just for SPMD Anymore

NASA Technical Reports Server (NTRS)

Becker, Jeffrey C.

1995-01-01

The Thinking Machines CM-5 platform was designed to run single program, multiple data (SPMD) applications, i.e., to run a single binary across all nodes of a partition, with each node possibly operating on different data. Certain classes of applications, such as multi-disciplinary computational fluid dynamics codes, are facilitated by the ability to have subsets of the partition nodes running different binaries. In order to extend the CM-5 system software to permit such applications, a multi-program loader was developed. This system is based on the dld loader which was originally developed for workstations. This paper provides a high level description of dld, and describes how it was ported to the CM-5 to provide support for multi-binary applications. Finally, it elaborates how the loader has been used to implement the CM-5 version of MPIRUN, a portable facility for running multi-disciplinary/multi-zonal MPI (Message-Passing Interface Standard) codes.

[Logistic regression model of noninvasive prediction for portal hypertensive gastropathy in patients with hepatitis B associated cirrhosis].

PubMed

Wang, Qingliang; Li, Xiaojie; Hu, Kunpeng; Zhao, Kun; Yang, Peisheng; Liu, Bo

2015-05-12

To explore the risk factors of portal hypertensive gastropathy (PHG) in patients with hepatitis B associated cirrhosis and establish a Logistic regression model of noninvasive prediction. The clinical data of 234 hospitalized patients with hepatitis B associated cirrhosis from March 2012 to March 2014 were analyzed retrospectively. The dependent variable was the occurrence of PHG while the independent variables were screened by binary Logistic analysis. Multivariate Logistic regression was used for further analysis of significant noninvasive independent variables. Logistic regression model was established and odds ratio was calculated for each factor. The accuracy, sensitivity and specificity of model were evaluated by the curve of receiver operating characteristic (ROC). According to univariate Logistic regression, the risk factors included hepatic dysfunction, albumin (ALB), bilirubin (TB), prothrombin time (PT), platelet (PLT), white blood cell (WBC), portal vein diameter, spleen index, splenic vein diameter, diameter ratio, PLT to spleen volume ratio, esophageal varices (EV) and gastric varices (GV). Multivariate analysis showed that hepatic dysfunction (X1), TB (X2), PLT (X3) and splenic vein diameter (X4) were the major occurring factors for PHG. The established regression model was Logit P=-2.667+2.186X1-2.167X2+0.725X3+0.976X4. The accuracy of model for PHG was 79.1% with a sensitivity of 77.2% and a specificity of 80.8%. Hepatic dysfunction, TB, PLT and splenic vein diameter are risk factors for PHG and the noninvasive predicted Logistic regression model was Logit P=-2.667+2.186X1-2.167X2+0.725X3+0.976X4.

Tracking Multiple People Online and in Real Time

DTIC Science & Technology

2015-12-21

NO. 0704-0188 3. DATES COVERED (From - To) - UU UU UU UU 21-12-2015 Approved for public release; distribution is unlimited. Tracking multiple people ...online and in real time We cast the problem of tracking several people as a graph partitioning problem that takes the form of an NP-hard binary...PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. Duke University 2200 West Main Street Suite 710 Durham, NC 27705 -4010 ABSTRACT Tracking multiple

Terrestrial Planet Formation Around Close Binary Stars

NASA Technical Reports Server (NTRS)

Lissauer, Jack J.; Quintana, Elisa V.

2003-01-01

Most stars reside in multiple star systems; however, virtually all models of planetary growth have assumed an isolated single star. Numerical simulations of the collapse of molecular cloud cores to form binary stars suggest that disks will form within such systems. Observations indirectly suggest disk material around one or both components within young binary star systems. If planets form at the right places within such circumstellar disks, they can remain in stable orbits within the binary star systems for eons. We are simulating the late stages of growth of terrestrial planets around close binary stars, using a new, ultrafast, symplectic integrator that we have developed for this purpose. The sum of the masses of the two stars is one solar mass, and the initial disk of planetary embryos is the same as that used for simulating the late stages of terrestrial planet growth within our Solar System and in the Alpha Centauri wide binary star system. Giant planets &are included in the simulations, as they are in most simulations of the late stages of terrestrial planet accumulation in our Solar System. When the stars travel on a circular orbit with semimajor axis of up to 0.1 AU about their mutual center of mass, the planetary embryos grow into a system of terrestrial planets that is statistically identical to those formed about single stars, but a larger semimajor axis and/or a significantly eccentric binary orbit can lead to significantly more dynamically hot terrestrial planet systems.

A SEARCH FOR X-RAY EMISSION FROM COLLIDING MAGNETOSPHERES IN YOUNG ECCENTRIC STELLAR BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Getman, Konstantin V.; Broos, Patrick S.; Kóspál, Ágnes

Among young binary stars whose magnetospheres are expected to collide, only two systems have been observed near periastron in the X-ray band: the low-mass DQ Tau and the older and more massive HD 152404. Both exhibit elevated levels of X-ray emission at periastron. Our goal is to determine whether colliding magnetospheres in young high-eccentricity binaries commonly produce elevated average levels of X-ray activity. This work is based on Chandra snapshots of multiple periastron and non-periastron passages in four nearby young eccentric binaries (Parenago 523, RX J1622.7-2325 Nw, UZ Tau E, and HD 152404). We find that for the merged samplemore » of all four binaries the current X-ray data show an increasing average X-ray flux near periastron (at a ∼2.5-sigma level). Further comparison of these data with the X-ray properties of hundreds of young stars in the Orion Nebula Cluster, produced by the Chandra Orion Ultradeep Project (COUP), indicates that the X-ray emission from the merged sample of our binaries cannot be explained within the framework of the COUP-like X-ray activity. However, due to the inhomogeneities of the merged binary sample and the relatively low statistical significance of the detected flux increase, these findings are regarded as tentative only. More data are needed to prove that the flux increase is real and is related to the processes of colliding magnetospheres.« less

The massive star binary fraction in young open clusters - II. NGC6611 (Eagle Nebula)

NASA Astrophysics Data System (ADS)

Sana, H.; Gosset, E.; Evans, C. J.

2009-12-01

Based on a set of over 100 medium- to high-resolution optical spectra collected from 2003 to 2009, we investigate the properties of the O-type star population in NGC6611 in the core of the Eagle Nebula (M16). Using a much more extended data set than previously available, we revise the spectral classification and multiplicity status of the nine O-type stars in our sample. We confirm two suspected binaries and derive the first SB2 orbital solutions for two systems. We further report that two other objects are displaying a composite spectrum, suggesting possible long-period binaries. Our analysis is supported by a set of Monte Carlo simulations, allowing us to estimate the detection biases of our campaign and showing that the latter do not affect our conclusions. The absolute minimal binary fraction in our sample is fmin = 0.44 but could be as high as 0.67 if all the binary candidates are confirmed. As in NGC6231 (see Paper I), up to 75 per cent of the O star population in NGC6611 are found in an O+OB system, thus implicitly excluding random pairing from a classical IMF as a process to describe the companion association in massive binaries. No statistical difference could be further identified in the binary fraction, mass-ratio and period distributions between NGC6231 and NGC 6611, despite the difference in age and environment of the two clusters.

A Search For X-Ray Emission From Colliding Magnetospheres In Young Eccentric Stellar Binaries

NASA Astrophysics Data System (ADS)

Getman, Konstantin V.; Broos, Patrick S.; Kóspál, Ágnes; Salter, Demerese M.; Garmire, Gordon P.

2016-12-01

Among young binary stars whose magnetospheres are expected to collide, only two systems have been observed near periastron in the X-ray band: the low-mass DQ Tau and the older and more massive HD 152404. Both exhibit elevated levels of X-ray emission at periastron. Our goal is to determine whether colliding magnetospheres in young high-eccentricity binaries commonly produce elevated average levels of X-ray activity. This work is based on Chandra snapshots of multiple periastron and non-periastron passages in four nearby young eccentric binaries (Parenago 523, RX J1622.7-2325 Nw, UZ Tau E, and HD 152404). We find that for the merged sample of all four binaries the current X-ray data show an increasing average X-ray flux near periastron (at a ˜2.5-sigma level). Further comparison of these data with the X-ray properties of hundreds of young stars in the Orion Nebula Cluster, produced by the Chandra Orion Ultradeep Project (COUP), indicates that the X-ray emission from the merged sample of our binaries cannot be explained within the framework of the COUP-like X-ray activity. However, due to the inhomogeneities of the merged binary sample and the relatively low statistical significance of the detected flux increase, these findings are regarded as tentative only. More data are needed to prove that the flux increase is real and is related to the processes of colliding magnetospheres.

The Log-Linear Cognitive Diagnostic Model (LCDM) as a Special Case of The General Diagnostic Model (GDM). Research Report. ETS RR-14-40

ERIC Educational Resources Information Center

von Davier, Matthias

2014-01-01

Diagnostic models combine multiple binary latent variables in an attempt to produce a latent structure that provides more information about test takers' performance than do unidimensional latent variable models. Recent developments in diagnostic modeling emphasize the possibility that multiple skills may interact in a conjunctive way within the…

Fast Exact Search in Hamming Space With Multi-Index Hashing.

PubMed

Norouzi, Mohammad; Punjani, Ali; Fleet, David J

2014-06-01

There is growing interest in representing image data and feature descriptors using compact binary codes for fast near neighbor search. Although binary codes are motivated by their use as direct indices (addresses) into a hash table, codes longer than 32 bits are not being used as such, as it was thought to be ineffective. We introduce a rigorous way to build multiple hash tables on binary code substrings that enables exact k-nearest neighbor search in Hamming space. The approach is storage efficient and straight-forward to implement. Theoretical analysis shows that the algorithm exhibits sub-linear run-time behavior for uniformly distributed codes. Empirical results show dramatic speedups over a linear scan baseline for datasets of up to one billion codes of 64, 128, or 256 bits.

Targeted numerical simulations of binary black holes for GW170104

NASA Astrophysics Data System (ADS)

Healy, J.; Lange, J.; O'Shaughnessy, R.; Lousto, C. O.; Campanelli, M.; Williamson, A. R.; Zlochower, Y.; Calderón Bustillo, J.; Clark, J. A.; Evans, C.; Ferguson, D.; Ghonge, S.; Jani, K.; Khamesra, B.; Laguna, P.; Shoemaker, D. M.; Boyle, M.; García, A.; Hemberger, D. A.; Kidder, L. E.; Kumar, P.; Lovelace, G.; Pfeiffer, H. P.; Scheel, M. A.; Teukolsky, S. A.

2018-03-01

In response to LIGO's observation of GW170104, we performed a series of full numerical simulations of binary black holes, each designed to replicate likely realizations of its dynamics and radiation. These simulations have been performed at multiple resolutions and with two independent techniques to solve Einstein's equations. For the nonprecessing and precessing simulations, we demonstrate the two techniques agree mode by mode, at a precision substantially in excess of statistical uncertainties in current LIGO's observations. Conversely, we demonstrate our full numerical solutions contain information which is not accurately captured with the approximate phenomenological models commonly used to infer compact binary parameters. To quantify the impact of these differences on parameter inference for GW170104 specifically, we compare the predictions of our simulations and these approximate models to LIGO's observations of GW170104.

Multiplicity At Early Stages Of Star Formation, Small Clusters. Observations Overview

NASA Astrophysics Data System (ADS)

Saito, Masao

2017-07-01

The SOLA (Soul of Lupus with ALMA) project is conducting comprehensive studies of the Lupus Molecular Clouds and their star formation processes covering 10-10^4 AU scale. Our goal is to exploit ALMA and other facilities over a wide wavelength range to establish a prototypical low-mass star forming scenario based on the Lupus region. In the presentation, we will focus on angular momentum in dense cores in a filament, molecular outflows from young stars, and Class 0/I binary survey in Lupus as well as overview of our projects. Our binary survey was conducted in ALMA cycle 2 and achieved at 0.2-0.3 arcsec resolution discovering new binary systems in Lupus. At the same time, we obtained EX Lup, EXor type burst source, data in ALMA Cycle 3.

Multiplicity at Early Stages of Star Formation, Small Clusters. Observations Overview

NASA Astrophysics Data System (ADS)

Saito, Masao

2017-06-01

The SOLA (Soul of Lupus with ALMA) project is conducting comprehensive studies of the Lupus Molecular Clouds and their star formation processes covering 10-10^4 AU scale. Our goal is to exploit ALMA and other facilities over a wide wavelength range to establish a prototypical low-mass star forming scenario based on the Lupus region. In the presentation, we will focus on angular momentum in dense cores in a filament, molecular outflows from young stars, and Class 0/I binary survey in Lupus as well as overview of our projects. Our binary survey was conducted in ALMA cycle 2 and achieved at 0.2-0.3 arcsec resolution discovering new binary systems in Lupus. At the same time, we obtained EX Lup, EXor type burst source, data in ALMA Cycle 3.

Quantum memory receiver for superadditive communication using binary coherent states

NASA Astrophysics Data System (ADS)

Klimek, Aleksandra; Jachura, Michał; Wasilewski, Wojciech; Banaszek, Konrad

2016-11-01

We propose a simple architecture based on multimode quantum memories for collective readout of classical information keyed using a pair coherent states, exemplified by the well-known binary phase shift keying format. Such a configuration enables demonstration of the superadditivity effect in classical communication over quantum channels, where the transmission rate becomes enhanced through joint detection applied to multiple channel uses. The proposed scheme relies on the recently introduced idea to prepare Hadamard sequences of input symbols that are mapped by a linear optical transformation onto the pulse position modulation format [Guha, S. Phys. Rev. Lett. 2011, 106, 240502]. We analyze two versions of readout based on direct detection and an optional Dolinar receiver which implements the minimum-error measurement for individual detection of a binary coherent state alphabet.

Quantum memory receiver for superadditive communication using binary coherent states.

PubMed

Klimek, Aleksandra; Jachura, Michał; Wasilewski, Wojciech; Banaszek, Konrad

2016-11-12

We propose a simple architecture based on multimode quantum memories for collective readout of classical information keyed using a pair coherent states, exemplified by the well-known binary phase shift keying format. Such a configuration enables demonstration of the superadditivity effect in classical communication over quantum channels, where the transmission rate becomes enhanced through joint detection applied to multiple channel uses. The proposed scheme relies on the recently introduced idea to prepare Hadamard sequences of input symbols that are mapped by a linear optical transformation onto the pulse position modulation format [Guha, S. Phys. Rev. Lett. 2011 , 106 , 240502]. We analyze two versions of readout based on direct detection and an optional Dolinar receiver which implements the minimum-error measurement for individual detection of a binary coherent state alphabet.

Speckle Interferometry at SOAR in 2014

NASA Astrophysics Data System (ADS)

Tokovinin, Andrei; Mason, Brian D.; Hartkopf, William I.; Mendez, Rene A.; Horch, Elliott P.

2015-08-01

The results of speckle interferometric observations at the Southern Astrophysical Research Telescope (SOAR) telescope in 2014 are given. A total of 1641 observations were taken, yielding 1636 measurements of 1218 resolved binary and multiple stars and 577 non-resolutions of 441 targets. We resolved for the first time 56 pairs, including some nearby astrometric or spectroscopic binaries and ten new subsystems in previously known visual binaries. The calibration of the data is checked by linear fits to the positions of 41 wide binaries observed at SOAR over several seasons. The typical calibration accuracy is 0.°1 in angle and 0.3% in pixel scale, while the measurement errors are on the order of 3 mas. The new data are used here to compute 194 binary star orbits, 148 of which are improvements on previous orbital solutions and 46 are first-time orbits. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

Systematic approach for simultaneously correcting the band-gap and p - d separation errors of common cation III-V or II-VI binaries in density functional theory calculations within a local density approximation

DOE PAGES

Wang, Jianwei; Zhang, Yong; Wang, Lin-Wang

2015-07-31

We propose a systematic approach that can empirically correct three major errors typically found in a density functional theory (DFT) calculation within the local density approximation (LDA) simultaneously for a set of common cation binary semiconductors, such as III-V compounds, (Ga or In)X with X = N,P,As,Sb, and II-VI compounds, (Zn or Cd)X, with X = O,S,Se,Te. By correcting (1) the binary band gaps at high-symmetry points , L, X, (2) the separation of p-and d-orbital-derived valence bands, and (3) conduction band effective masses to experimental values and doing so simultaneously for common cation binaries, the resulting DFT-LDA-based quasi-first-principles methodmore » can be used to predict the electronic structure of complex materials involving multiple binaries with comparable accuracy but much less computational cost than a GW level theory. This approach provides an efficient way to evaluate the electronic structures and other material properties of complex systems, much needed for material discovery and design.« less

Numerical relativity simulations of precessing binary neutron star mergers

NASA Astrophysics Data System (ADS)

Dietrich, Tim; Bernuzzi, Sebastiano; Brügmann, Bernd; Ujevic, Maximiliano; Tichy, Wolfgang

2018-03-01

We present the first set of numerical relativity simulations of binary neutron mergers that include spin precession effects and are evolved with multiple resolutions. Our simulations employ consistent initial data in general relativity with different spin configurations and dimensionless spin magnitudes ˜0.1 . They start at a gravitational-wave frequency of ˜392 Hz and cover more than 1 precession period and about 15 orbits up to merger. We discuss the spin precession dynamics by analyzing coordinate trajectories, quasilocal spin measurements, and energetics, by comparing spin aligned, antialigned, and irrotational configurations. Gravitational waveforms from different spin configuration are compared by calculating the mismatch between pairs of waveforms in the late inspiral. We find that precession effects are not distinguishable from nonprecessing configurations with aligned spins for approximately face-on binaries, while the latter are distinguishable from nonspinning configurations. Spin precession effects are instead clearly visible for approximately edge-on binaries. For the parameters considered here, precession does not significantly affect the characteristic postmerger gravitational-wave frequencies nor the mass ejection. Our results pave the way for the modeling of spin precession effects in the gravitational waveform from binary neutron star events.

Mesoscopic Community Structure of Financial Markets Revealed by Price and Sign Fluctuations.

PubMed

Almog, Assaf; Besamusca, Ferry; MacMahon, Mel; Garlaschelli, Diego

2015-01-01

The mesoscopic organization of complex systems, from financial markets to the brain, is an intermediate between the microscopic dynamics of individual units (stocks or neurons, in the mentioned cases), and the macroscopic dynamics of the system as a whole. The organization is determined by "communities" of units whose dynamics, represented by time series of activity, is more strongly correlated internally than with the rest of the system. Recent studies have shown that the binary projections of various financial and neural time series exhibit nontrivial dynamical features that resemble those of the original data. This implies that a significant piece of information is encoded into the binary projection (i.e. the sign) of such increments. Here, we explore whether the binary signatures of multiple time series can replicate the same complex community organization of the financial market, as the original weighted time series. We adopt a method that has been specifically designed to detect communities from cross-correlation matrices of time series data. Our analysis shows that the simpler binary representation leads to a community structure that is almost identical with that obtained using the full weighted representation. These results confirm that binary projections of financial time series contain significant structural information.

COLLISIONAL EVOLUTION OF ULTRA-WIDE TRANS-NEPTUNIAN BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parker, Alex H.; Kavelaars, J. J., E-mail: alexhp@uvic.ca

2012-01-10

The widely separated, near-equal mass binaries hosted by the cold classical Kuiper Belt are delicately bound and subject to disruption by many perturbing processes. We use analytical arguments and numerical simulations to determine their collisional lifetimes given various impactor size distributions and include the effects of mass loss and multiple impacts over the lifetime of each system. These collisional lifetimes constrain the population of small (R {approx}> 1 km) objects currently residing in the Kuiper Belt and confirm that the size distribution slope at small size cannot be excessively steep-likely q {approx}< 3.5. We track mutual semimajor axis, inclination, andmore » eccentricity evolution through our simulations and show that it is unlikely that the wide binary population represents an evolved tail of the primordially tight binary population. We find that if the wide binaries are a collisionally eroded population, their primordial mutual orbit planes must have preferred to lie in the plane of the solar system. Finally, we find that current limits on the size distribution at small radii remain high enough that the prospect of detecting dust-producing collisions in real time in the Kuiper Belt with future optical surveys is feasible.« less

Systematic approach for simultaneously correcting the band-gap and p -d separation errors of common cation III-V or II-VI binaries in density functional theory calculations within a local density approximation

NASA Astrophysics Data System (ADS)

Wang, Jianwei; Zhang, Yong; Wang, Lin-Wang

2015-07-01

We propose a systematic approach that can empirically correct three major errors typically found in a density functional theory (DFT) calculation within the local density approximation (LDA) simultaneously for a set of common cation binary semiconductors, such as III-V compounds, (Ga or In)X with X =N ,P ,As ,Sb , and II-VI compounds, (Zn or Cd)X , with X =O ,S ,Se ,Te . By correcting (1) the binary band gaps at high-symmetry points Γ , L , X , (2) the separation of p -and d -orbital-derived valence bands, and (3) conduction band effective masses to experimental values and doing so simultaneously for common cation binaries, the resulting DFT-LDA-based quasi-first-principles method can be used to predict the electronic structure of complex materials involving multiple binaries with comparable accuracy but much less computational cost than a GW level theory. This approach provides an efficient way to evaluate the electronic structures and other material properties of complex systems, much needed for material discovery and design.

Do classic blood biomarkers of JSLE identify active lupus nephritis? Evidence from the UK JSLE Cohort Study.

PubMed

Smith, E M D; Jorgensen, A L; Beresford, M W

2017-10-01

Background Lupus nephritis (LN) affects up to 80% of juvenile-onset systemic lupus erythematosus (JSLE) patients. The value of commonly available biomarkers, such as anti-dsDNA antibodies, complement (C3/C4), ESR and full blood count parameters in the identification of active LN remains uncertain. Methods Participants from the UK JSLE Cohort Study, aged <16 years at diagnosis, were categorized as having active or inactive LN according to the renal domain of the British Isles Lupus Assessment Group score. Classic biomarkers: anti-dsDNA, C3, C4, ESR, CRP, haemoglobin, total white cells, neutrophils, lymphocytes, platelets and immunoglobulins were assessed for their ability to identify active LN using binary logistic regression modeling, with stepAIC function applied to select a final model. Receiver-operating curve analysis was used to assess diagnostic accuracy. Results A total of 370 patients were recruited; 191 (52%) had active LN and 179 (48%) had inactive LN. Binary logistic regression modeling demonstrated a combination of ESR, C3, white cell count, neutrophils, lymphocytes and IgG to be best for the identification of active LN (area under the curve 0.724). Conclusions At best, combining common classic blood biomarkers of lupus activity using multivariate analysis provides a 'fair' ability to identify active LN. Urine biomarkers were not included in these analyses. These results add to the concern that classic blood biomarkers are limited in monitoring discrete JSLE manifestations such as LN.

The rate of adherence to urate-lowering therapy and associated factors in Chinese gout patients: a cross-sectional study.

PubMed

Yin, Rulan; Cao, Haixia; Fu, Ting; Zhang, Qiuxiang; Zhang, Lijuan; Li, Liren; Gu, Zhifeng

2017-07-01

The aim of this study was to assess adherence rate and predictors of non-adherence with urate-lowering therapy (ULT) in Chinese gout patients. A cross-sectional study was administered to 125 gout patients using the Compliance Questionnaire on Rheumatology (CQR) for adherence to ULT. Patients were asked to complete the Treatment Satisfaction Questionnaire for Medication version II, Health Assessment Questionnaire, Confidence in Gout Treatment Questionnaire, Gout Knowledge Questionnaire, Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, and 36-Item Short Form Health Survey. Data were analyzed by independent sample t test, rank sum test, Chi-square analysis as well as binary stepwise logistic regression modeling. The data showed that the rate of adherence (CQR ≥80%) to ULT was 9.6% in our investigated gout patients. Adherence was associated with functional capacity, gout-related knowledge, satisfaction with medication, confidence in gout treatment and mental components summary. Multivariable analysis of binary stepwise logistic regression identified gout-related knowledge and satisfaction of effectiveness with medication was the independent risk factors of medication non-adherence. Patients unaware of gout-related knowledge, or with low satisfaction of effectiveness with medication, were more likely not to adhere to ULT. Non-adherence to ULT among gout patients is exceedingly common, particularly in patients unaware of gout-related knowledge, or with low satisfaction of effectiveness with medication. These findings could help medical personnel develop useful interventions to improve gout patients' medication adherence.

Financial performance monitoring of the technical efficiency of critical access hospitals: a data envelopment analysis and logistic regression modeling approach.

PubMed

Wilson, Asa B; Kerr, Bernard J; Bastian, Nathaniel D; Fulton, Lawrence V

2012-01-01

From 1980 to 1999, rural designated hospitals closed at a disproportionally high rate. In response to this emergent threat to healthcare access in rural settings, the Balanced Budget Act of 1997 made provisions for the creation of a new rural hospital--the critical access hospital (CAH). The conversion to CAH and the associated cost-based reimbursement scheme significantly slowed the closure rate of rural hospitals. This work investigates which methods can ensure the long-term viability of small hospitals. This article uses a two-step design to focus on a hypothesized relationship between technical efficiency of CAHs and a recently developed set of financial monitors for these entities. The goal is to identify the financial performance measures associated with efficiency. The first step uses data envelopment analysis (DEA) to differentiate efficient from inefficient facilities within a data set of 183 CAHs. Determining DEA efficiency is an a priori categorization of hospitals in the data set as efficient or inefficient. In the second step, DEA efficiency is the categorical dependent variable (efficient = 0, inefficient = 1) in the subsequent binary logistic regression (LR) model. A set of six financial monitors selected from the array of 20 measures were the LR independent variables. We use a binary LR to test the null hypothesis that recently developed CAH financial indicators had no predictive value for categorizing a CAH as efficient or inefficient, (i.e., there is no relationship between DEA efficiency and fiscal performance).

Predictors associated with the willingness to take human papilloma virus vaccination.

PubMed

Naing, Cho; Pereira, Joanne; Abe, Tatsuki; Eh Zhen Wei, Daniel; Rahman Bajera, Ibrizah Binti Abdul; Kavinda Perera, Undugodage Heshan

2012-04-01

Human papilloma virus vaccine is considered to be the primary form of cervical cancer prevention. The objectives were (1) to determine knowledge about, and perception of human papilloma virus infection in relation to cervical cancer, (2) to explore the intention of the community to be vaccinated with human papilloma virus vaccine, and (3) to identify variables that could predict the likelihood of uptake of the vaccine. A cross-sectional survey was carried out in a semi-urban Town of Malaysia, using a pre-tested structured questionnaire. Summary statistics, Pearson chi-square test and a binary logistic regression were used for data analysis. A total of 232 respondents were interviewed. Overall, only a few had good knowledge related to human papilloma virus (14%) or vaccination (8%). Many had misconceptions that it could be transmitted through blood transfusion (57%). Sixty percent had intention to take vaccination. In the binary logistic model, willingness to take vaccination was significant with 'trusts that vaccination would be effective for prevention of cervical cancer' (P = 0.001), 'worries for themselves' (P < 0.001) or 'their family members' (P = 0.003) and 'being Indian ethnicity' (P = 0.024). The model could fairly predict the likelihood of uptake of the vaccine (Cox & Snell R(2) = .415; Nagelkerke R(2) = 0.561). Results indicate that intensive health education dispelling misconception and risk perception towards human papilloma virus infection and cervical cancer would be helpful to increase the acceptability of vaccination program.

Socioeconomic and Demographic Disparities in Knowledge of Reproductive Healthcare among Female University Students in Bangladesh

PubMed Central

Islam Mondal, Md. Nazrul; Nasir Ullah, Md. Monzur Morshad; Khan, Md. Nuruzzaman; Islam, Mohammad Zamirul; Islam, Md. Nurul; Moni, Sabiha Yasmin; Hoque, Md. Nazrul; Rahman, Md. Mashiur

2015-01-01

Background: Reproductive health (RH) is a critical component of women’s health and overall well-being around the world, especially in developing countries. We examine the factors that determine knowledge of RH care among female university students in Bangladesh. Methods: Data on 300 female students were collected from Rajshahi University, Bangladesh through a structured questionnaire using purposive sampling technique. The data were used for univariate analysis, to carry out the description of the variables; bivariate analysis was used to examine the associations between the variables; and finally, multivariate analysis (binary logistic regression model) was used to examine and fit the model and interpret the parameter estimates, especially in terms of odds ratios. Results: The results revealed that more than one-third (34.3%) respondents do not have sufficient knowledge of RH care. The χ2-test identified the significant (p < 0.05) associations between respondents’ knowledge of RH care with respondents’ age, education, family type, watching television; and knowledge about pregnancy, family planning, and contraceptive use. Finally, the binary logistic regression model identified respondents’ age, education, family type; and knowledge about family planning, and contraceptive use as the significant (p < 0.05) predictors of RH care. Conclusions and Global Health Implications: Knowledge of RH care among female university students was found unsatisfactory. Government and concerned organizations should promote and strengthen various health education programs to focus on RH care especially for the female university students in Bangladesh. PMID:27622005

Factors associated with trait anger level of juvenile offenders in Hubei province: A binary logistic regression analysis.

PubMed

Tang, Li-Na; Ye, Xiao-Zhou; Yan, Qiu-Ge; Chang, Hong-Juan; Ma, Yu-Qiao; Liu, De-Bin; Li, Zhi-Gen; Yu, Yi-Zhen

2017-02-01

The risk factors of high trait anger of juvenile offenders were explored through questionnaire study in a youth correctional facility of Hubei province, China. A total of 1090 juvenile offenders in Hubei province were investigated by self-compiled social-demographic questionnaire, Childhood Trauma Questionnaire (CTQ), and State-Trait Anger Expression Inventory-II (STAXI-II). The risk factors were analyzed by chi-square tests, correlation analysis, and binary logistic regression analysis with SPSS 19.0. A total of 1082 copies of valid questionnaires were collected. High trait anger group (n=316) was defined as those who scored in the upper 27th percentile of STAXI-II trait anger scale (TAS), and the rest were defined as low trait anger group (n=766). The risk factors associated with high level of trait anger included: childhood emotional abuse, childhood sexual abuse, step family, frequent drug abuse, and frequent internet using (P<0.05 or P<0.01). Birth sequence, number of sibling, ranking in the family, identity of the main care-taker, the education level of care-taker, educational style of care-taker, family income, relationship between parents, social atmosphere of local area, frequent drinking, and frequent smoking did not predict to high level of trait anger (P>0.05). It was suggested that traumatic experience in childhood and unhealthy life style may significantly increase the level of trait anger in adulthood. The risk factors of high trait anger and their effects should be taken into consideration seriously.

Depression and associated variables in people over 50 years in Spain.

PubMed

Portellano-Ortiz, Cristina; Garre-Olmo, Josep; Calvó-Perxas, Laia; Conde-Sala, Josep Lluís

2016-12-06

Depression is a common and disabling psychiatric disorder in adulthood and is associated with higher mortality and functional disability. To determine the association between clinical and sociodemographic variables with depression in a sample of people over 50 years old living in Spain, and compare the prevalence of depression with the other Survey of Health, Ageing and Retirement (SHARE) countries. There were 5,830 participants in the Spanish sample of the Wave 5, 2013, of SHARE. Tools used: EURO-D (Depression) and CASP-12 (Quality of Life). Bivariate, and binary logistic. The variables associated with depression in the binary logistic regression (EURO-D ≥4) were poor self-perceived physical health (OR=13.34; 95% CI: 9.74-18.27), having more than 2 difficulties in Activities of Daily Living (ADL) (OR=4.46; 95% CI: 3.13-6.34) and female gender (OR=2.16; 95% CI: 1.83-2.56). Depression was more common among participants with Alzheimer (76.4%), emotional disorders (73.9%), Parkinson (57.4%), hip fracture (55.4%), and rheumatism (50.9%). Compared with other European countries, Spain had a percentage of people with depression (29.3%) that was higher than the European average (27.9%). The most important variables associated with depression were poor perceived physical health, presence of difficulties in ADL, and female gender. Copyright © 2016 SEP y SEPB. Publicado por Elsevier España, S.L.U. All rights reserved.

Predictors of postoperative outcomes of cubital tunnel syndrome treatments using multiple logistic regression analysis.

PubMed

Suzuki, Taku; Iwamoto, Takuji; Shizu, Kanae; Suzuki, Katsuji; Yamada, Harumoto; Sato, Kazuki

2017-05-01

This retrospective study was designed to investigate prognostic factors for postoperative outcomes for cubital tunnel syndrome (CubTS) using multiple logistic regression analysis with a large number of patients. Eighty-three patients with CubTS who underwent surgeries were enrolled. The following potential prognostic factors for disease severity were selected according to previous reports: sex, age, type of surgery, disease duration, body mass index, cervical lesion, presence of diabetes mellitus, Workers' Compensation status, preoperative severity, and preoperative electrodiagnostic testing. Postoperative severity of disease was assessed 2 years after surgery by Messina's criteria which is an outcome measure specifically for CubTS. Bivariate analysis was performed to select candidate prognostic factors for multiple linear regression analyses. Multiple logistic regression analysis was conducted to identify the association between postoperative severity and selected prognostic factors. Both bivariate and multiple linear regression analysis revealed only preoperative severity as an independent risk factor for poor prognosis, while other factors did not show any significant association. Although conflicting results exist regarding prognosis of CubTS, this study supports evidence from previous studies and concludes early surgical intervention portends the most favorable prognosis. Copyright © 2017 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

Binary Sources and Binary Lenses in Microlensing Surveys of MACHOs

NASA Astrophysics Data System (ADS)

Petrovic, N.; Di Stefano, R.; Perna, R.

2003-12-01

Microlensing is an intriguing phenomenon which may yield information about the nature of dark matter. Early observational searches identified hundreds of microlensing light curves. The data set consisted mainly of point-lens light curves and binary-lens events in which the light curves exhibit caustic crossings. Very few mildly perturbed light curves were observed, although this latter type should constitute the majority of binary lens light curves. Di Stefano (2001) has suggested that the failure to take binary effects into account may have influenced the estimates of optical depth derived from microlensing surveys. The work we report on here is the first step in a systematic analysis of binary lenses and binary sources and their impact on the results of statistical microlensing surveys. In order to asses the problem, we ran Monte-Carlo simulations of various microlensing events involving binary stars (both as the source and as the lens). For each event with peak magnification > 1.34, we sampled the characteristic light curve and recorded the chi squared value when fitting the curve with a point lens model; we used this to asses the perturbation rate. We also recorded the parameters of each system, the maximum magnification, the times at which each light curve started and ended and the number of caustic crossings. We found that both the binarity of sources and the binarity of lenses increased the lensing rate. While the binarity of sources had a negligible effect on the perturbation rates of the light curves, the binarity of lenses had a notable effect. The combination of binary sources and binary lenses produces an observable rate of interesting events exhibiting multiple "repeats" in which the magnification rises above and dips below 1.34 several times. Finally, the binarity of lenses impacted both the durations of the events and the maximum magnifications. This work was supported in part by the SAO intern program (NSF grant AST-9731923) and NASA contracts NAS8-39073 and NAS8-38248 (CXC).

Gender differences in depressive symptom profiles and patterns of psychotropic drug usage in Asian patients with depression: Findings from the Research on Asian Psychotropic Prescription Patterns for Antidepressants study.

PubMed

Park, Seon-Cheol; Lee, Min-Soo; Shinfuku, Naotaka; Sartorius, Norman; Park, Yong Chon

2015-09-01

The purpose of this study was to investigate whether there were gender-specific depressive symptom profiles or gender-specific patterns of psychotropic agent usage in Asian patients with depression. Clinical data from the Research on Asian Psychotropic Prescription Patterns for Antidepressant study (1171 depressed patients) were used to determine gender differences by analysis of covariates for continuous variables and by logistic regression analysis for discrete variables. In addition, a binary logistic regression model was fitted to identify independent clinical correlates of the gender-specific pattern on psychotropic drug usage. Men were more likely than women to have loss of interest (adjusted odds ratio = 1.379, p = 0.009), fatigue (adjusted odds ratio = 1.298, p = 0.033) and concurrent substance abuse (adjusted odds ratio = 3.793, p = 0.008), but gender differences in other symptom profiles and clinical features were not significant. Men were also more likely than women to be prescribed adjunctive therapy with a second-generation antipsychotic (adjusted odds ratio = 1.320, p = 0.044). However, men were less likely than women to have suicidal thoughts/acts (adjusted odds ratio = 0.724, p = 0.028). Binary logistic regression models revealed that lower age (odds ratio = 0.986, p = 0.027) and current hospitalization (odds ratio = 3.348, p < 0.0001) were independent clinical correlates of use of second-generation antipsychotics as adjunctive therapy for treating depressed Asian men. Unique gender-specific symptom profiles and gender-specific patterns of psychotropic drug usage can be identified in Asian patients with depression. Hence, ethnic and cultural influences on the gender preponderance of depression should be considered in the clinical psychiatry of Asian patients. © The Royal Australian and New Zealand College of Psychiatrists 2015.

A wide deep infrared look at the Pleiades with UKIDSS: new constraints on the substellar binary fraction and the low-mass initial mass function

NASA Astrophysics Data System (ADS)

Lodieu, N.; Dobbie, P. D.; Deacon, N. R.; Hodgkin, S. T.; Hambly, N. C.; Jameson, R. F.

2007-09-01

We present the results of a deep wide-field near-infrared survey of 12 deg2 of the Pleiades conducted as part of the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Galactic Cluster Survey (GCS). We have extracted over 340 high-probability proper motion (PM) members down to 0.03 Msolar using a combination of UKIDSS photometry and PM measurements obtained by cross-correlating the GCS with data from the Two Micron All Sky Survey, the Isaac Newton Telescope and the Canada-France-Hawaii Telescope. Additionally, we have unearthed 73 new candidate brown dwarf (BD) members on the basis of five-band UKIDSS photometry alone. We have identified 23 substellar multiple system candidates out of 63 candidate BDs from the (Y - K, Y) and (J - K, J) colour-magnitude diagrams, yielding a binary frequency of 28-44 per cent in the 0.075-0.030 Msolar mass range. Our estimate is three times larger than the binary fractions reported from high-resolution imaging surveys of field ultracool dwarfs and Pleiades BDs. However, it is marginally consistent with our earlier `peculiar' photometric binary fraction of 50 +/- 10 per cent presented by Pinfield et al., in good agreement with the 32-45 per cent binary fraction derived from the recent Monte Carlo simulations of Maxted & Jeffries and compatible with the 26 +/- 10 per cent frequency recently estimated by Basri & Reiners. A tentative estimate of the mass ratios from photometry alone seems to support the hypothesis that binary BDs tend to reside in near equal-mass ratio systems. In addition, the recovery of four Pleiades members targeted by high-resolution imaging surveys for multiplicity studies suggests that half of the binary candidates may have separations below the resolution limit of the Hubble Space Telescope or current adaptive optics facilities at the distance of the Pleiades (a ~7 au). Finally, we have derived luminosity and mass functions from the sample of photometric candidates with membership probabilities. The mass function is well modelled by a lognormal peaking at 0.24Msolar and is in agreement with previous studies in the Pleiades. Based on observations made with the United Kingdom Infrared Telescope, operated by the Joint Astronomy Centre on behalf of the UK Particle Physics and Astronomy Research Council. E-mail: nlodieu@iac.es

Accretion and Outflows in X-ray Binaries: What's Really Going on During X-ray Quiescence

NASA Astrophysics Data System (ADS)

MacDonald, Rachel K. D.; Bailyn, Charles D.; Buxton, Michelle

2015-01-01

X-ray binaries, consisting of a star and a stellar-mass black hole, are wonderful laboratories for studying accretion and outflows. They evolve on timescales quite accessible to us, unlike their supermassive cousins, and allow the possibility of gaining a deeper understanding of these two common astrophysical processes. Different wavelength regimes reveal different aspects of the systems: radio emission is largely generated by outflows and jets, X-ray emission by inner accretion flows, and optical/infrared (OIR) emission by the outer disk and companion star. The search for relationships between these different wavelengths is thus an area of active research, aiming to reveal deeper connections between accretion and outflows.Initial evidence for a strong, tight correlation between radio and X-ray emission has weakened as further observations and newly-discovered sources have been obtained. This has led to discussions of multiple tracks or clusters, or the possibility that no overall relation exists for the currently-known population of X-ray binaries. Our ability to distinguish among these options is hampered by a relative lack of observations at lower luminosities, and especially of truly X-ray quiescent (non-outbursting) systems. Although X-ray binaries spend the bulk of their existence in quiescence, few quiescent sources have been observed and multiple observations of individual sources are largely nonexistent. Here we discuss new observations of the lowest-luminosity quiescent X-ray binary, A0620-00, and the place this object occupies in investigations of the radio/X-ray plane. For the first time, we also incorporate simultaneous OIR data with the radio and X-ray data.In December 2013 we took simultaneous observations of A0620-00 in the X-ray (Chandra), the radio (EVLA), and the OIR (SMARTS 1.3m). These X-ray and radio data allowed us to investigate similarities among quiescent X-ray binaries, and changes over time for this individual object, in the radio/X-ray plane. In addition, our OIR observations allowed us to examine the radio and X-ray information in relation to the different OIR states of behavior (passive and active) known to exist during X-ray quiescence.

Super-massive binary black holes in galaxies. Dynamical models and observed structures in Arp 5, 87, 214, 240, and NGC 4027, 6946

NASA Astrophysics Data System (ADS)

Anosova, Joanna P.

2017-06-01

On 14 Sept, 2015 The LIGO reported the first direct detection of gravitational waves and the first direct observation of a binary black hole. These observations demonstrate the existence of binary black holes in stellar systems predicted by Einstein in his general theory of relativity a century earlier.A lot of violent and complicated phenomena take place on different scales in the Universe. Many of them may be caused by multiple centers of gravitational attraction: planetary rings, accretion discs of various scales, peculiar structures of single galaxies and interacting galaxies. In this work, we show that various features of celestial objects can be understood by assuming the existence of two dominant centers of gravity in stellar systems.We study numerically the dynamical evolution of models with the central super-massive binary black holes and extended shells with numerous low-mass particles inside and around the orbits of binaries. These particles could be star clusters or gas and dust complexes. We consider several tens of thousands of initial conditions for the general three-body problem and compile them. We studied the dynamical evolution of all spherical shells together and separately. Our method permits us to study the individual trajectories of particles, their close double and triple approaches, and inspect the time-depending structures in the models. Multiple runs of the models allow us to classify the numerous strong triple interactions of the binary components with low-mass particles; frequently, the "gravitational slingshot" effect occurs in the center of systems. Such strong interactions of bodies are results in various structures with "dumb-bell" bars, close and open spirals, different types of flows, jets etc. These structures are often very similar the observed structures of galaxies.We found some combinations of the initial conditions and model parameters that produce at some time similar structures as that found in the galaxies Arp 5, 87, 214, 240, and NGC 4027, 6946. Our Figures show results of such comparison and the past and future evolution of our models.

Accounting for informatively missing data in logistic regression by means of reassessment sampling.

PubMed

Lin, Ji; Lyles, Robert H

2015-05-20

We explore the 'reassessment' design in a logistic regression setting, where a second wave of sampling is applied to recover a portion of the missing data on a binary exposure and/or outcome variable. We construct a joint likelihood function based on the original model of interest and a model for the missing data mechanism, with emphasis on non-ignorable missingness. The estimation is carried out by numerical maximization of the joint likelihood function with close approximation of the accompanying Hessian matrix, using sharable programs that take advantage of general optimization routines in standard software. We show how likelihood ratio tests can be used for model selection and how they facilitate direct hypothesis testing for whether missingness is at random. Examples and simulations are presented to demonstrate the performance of the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.

Comparison of arboreal beetle catches in wet and dry collection cups with lindgren multiple funnel traps

Treesearch

Daniel R. Miller; Donald A. Duerr

2008-01-01

We compared the effectiveness of a dry collection cup (with an insecticide killing strip) to a wet collection cup (containing antifreeze) for use with Lindgren multiple-funnel traps in catching several common species of bark and wood-boring beetles, and their associates in southern pine forests. All traps were baited with either the binary combination of ethanol and...

Adherence to multiple micronutrient powders and associated factors in children aged 6 to 35 months treated in sentinel health facilities, Ministry of Health of Peru.

PubMed

Munares-García, Oscar; Gómez-Guizado, Guillermo

2016-01-01

Anemia in children is a public health issue, and the current strategies include treatment and iron supplementation, but their level of adherence or compliance is unknown. To consider the adherence to multiple micronutrient powders and the associated factors. Epidemiological study of active surveillance through sentinel facilities in 2,024 children aged 6 to 35 months treated in health facilities of the Ministry of Health of Peru, from October to December 2014. Household visits were conducted in which counting of multiple micronutrient powders was applied and determined an adherence of consumption ≥ 90% envelopes, besides a form on the associated factors (anemia knowledge, iron-rich food, side effects, dosage regimen, drugs used, and motivation) was applied. Descriptive statistics, χ² test, Odds Ratio with a 95% confidence interval (CI), and binary logistic regression or adjusted Odds Ratio (aOR) were used. Of all, 79.1% participants were aged 6 to 23 months; 75.9% received multiple micronutrient powders; and the adherence was equivalent to 24.4% (95%CI 22.3 - 26.6). The factors: continue supplementation (OR = 3.5; 95%CI 1.7 - 7.5); no nausea (OR = 3.0; 95%CI 2.0 - 4.3); no use of antibiotics (OR = 2.5; 95%CI 1.7 - 3.6); and intention to continue treatment (OR = 2.3; 95%CI 1.3 - 4.1) were associated with adherence. The variables: thought of continuing treatment (aOR = 2.6; 95%CI 1.1 - 6.1); presence of side effects, but no discontinuation of the treatment (aOR = 2.5; 95%CI 1.4 - 4.3); no use of antibiotics (aOR = 2.0; 95%CI 1.1 - 3.4); and belief that not only drugs cure anemia (aOR = 1.6; 95%CI 1.0 - 2.6) were associated in the multivariate analysis. There was a low prevalence of adherence to a demanding cut-off point (≥ 90% of envelopes of multiple micronutrient powders), and the associated factors are associated with absence of infections, side effects, and mother's beliefs.

Multivariate meta-analysis using individual participant data.

PubMed

Riley, R D; Price, M J; Jackson, D; Wardle, M; Gueyffier, F; Wang, J; Staessen, J A; White, I R

2015-06-01

When combining results across related studies, a multivariate meta-analysis allows the joint synthesis of correlated effect estimates from multiple outcomes. Joint synthesis can improve efficiency over separate univariate syntheses, may reduce selective outcome reporting biases, and enables joint inferences across the outcomes. A common issue is that within-study correlations needed to fit the multivariate model are unknown from published reports. However, provision of individual participant data (IPD) allows them to be calculated directly. Here, we illustrate how to use IPD to estimate within-study correlations, using a joint linear regression for multiple continuous outcomes and bootstrapping methods for binary, survival and mixed outcomes. In a meta-analysis of 10 hypertension trials, we then show how these methods enable multivariate meta-analysis to address novel clinical questions about continuous, survival and binary outcomes; treatment-covariate interactions; adjusted risk/prognostic factor effects; longitudinal data; prognostic and multiparameter models; and multiple treatment comparisons. Both frequentist and Bayesian approaches are applied, with example software code provided to derive within-study correlations and to fit the models. © 2014 The Authors. Research Synthesis Methods published by John Wiley & Sons, Ltd.

Binaries and triples among asteroid pairs

NASA Astrophysics Data System (ADS)

Pravec, Petr; Scheirich, Peter; Kušnirák, Peter; Hornoch, Kamil; Galád, Adrián

2015-08-01

Despite major achievements obtained during the past two decades, our knowledge of the population and properties of small binary and multiple asteroid systems is still far from advanced. There is a numerous indirect evidence for that most small asteroid systems were formed by rotational fission of cohesionless parent asteroids that were spun up to the critical frequency presumably by YORP, but details of the process are lacking. Furthermore, as we proceed with observations of more and more binary and paired asteroids, we reveal new facts that substantially refine and sometimes change our understanding of the asteroid systems. One significant new finding we have recently obtained is that primaries of many asteroid pairs are actually binary or triple systems. The first such case found is (3749) Balam (Vokrouhlický, ApJL 706, L37, 2009). We have found 9 more binary systems among asteroid pairs within our ongoing NEOSource photometric project since October 2012. They are (6369) 1983 UC, (8306) Shoko, (9783) Tensho-kan, (10123) Fideoja, (21436) Chaoyichi, (43008) 1999 UD31, (44620) 1999 RS43, (46829) 1998 OS14 and (80218) 1999 VO123. We will review their characteristics. These paired binaries as we call them are mostly similar to binaries in the general ("background") population (of unpaired asteroids), but there are a few trends. The paired binaries tend to have larger secondaries with D_2/D_1 = 0.3 to 0.5 and they also tend to be wider systems with 8 of the 10 having orbital periods between 30 and 81 hours, than average among binaries in the general population. There may be also a larger fraction of triples; (3749) Balam is a confirmed triple, having a larger close and a smaller distant satellite, and (8306) Shoko and (10123) Fideoja are suspect triples as they show additional rotational lightcurve components with periods of 61 and 38.8 h that differ from the orbital period of 36.2 and 56.5 h, respectively. The unbound secondaries tend to be of the same size or smaller (with one exception) than the bound orbiting secondaries. I will compare the observed properties of the paired binaries to predictions from theories of formation of asteroid binaries and pairs.

Aligning Metabolic Pathways Exploiting Binary Relation of Reactions.

PubMed

Huang, Yiran; Zhong, Cheng; Lin, Hai Xiang; Huang, Jing

2016-01-01

Metabolic pathway alignment has been widely used to find one-to-one and/or one-to-many reaction mappings to identify the alternative pathways that have similar functions through different sets of reactions, which has important applications in reconstructing phylogeny and understanding metabolic functions. The existing alignment methods exhaustively search reaction sets, which may become infeasible for large pathways. To address this problem, we present an effective alignment method for accurately extracting reaction mappings between two metabolic pathways. We show that connected relation between reactions can be formalized as binary relation of reactions in metabolic pathways, and the multiplications of zero-one matrices for binary relations of reactions can be accomplished in finite steps. By utilizing the multiplications of zero-one matrices for binary relation of reactions, we efficiently obtain reaction sets in a small number of steps without exhaustive search, and accurately uncover biologically relevant reaction mappings. Furthermore, we introduce a measure of topological similarity of nodes (reactions) by comparing the structural similarity of the k-neighborhood subgraphs of the nodes in aligning metabolic pathways. We employ this similarity metric to improve the accuracy of the alignments. The experimental results on the KEGG database show that when compared with other state-of-the-art methods, in most cases, our method obtains better performance in the node correctness and edge correctness, and the number of the edges of the largest common connected subgraph for one-to-one reaction mappings, and the number of correct one-to-many reaction mappings. Our method is scalable in finding more reaction mappings with better biological relevance in large metabolic pathways.

Is stellar multiplicity universal? Tight stellar binaries in the Orion Nebula Cluster

NASA Astrophysics Data System (ADS)

Duchêne, Gaspard; Lacour, S.; Moraux, E.; Goodwin, S.; Bouvier, J.

2018-05-01

We present a survey for the tightest visual binaries among 0.3-2 M⊙ members the Orion Nebula Cluster (ONC). Among 42 targets, we discovered 13 new 0{^''.}025-0{^''.}15 companions. Accounting for the Branch bias, we find a companion star fraction (CSF) in the 10-60 au range of 21^{+8}_{-5}%, consistent with that observed in other star-forming regions (SFRs) and twice as high as among field stars; this excess is found with a high level of confidence. Since our sample is dominated by disk-bearing targets, this indicates that disk disruption by close binaries is inefficient, or has not yet taken place, in the ONC. The resulting separation distribution in the ONC drops sharply outside 60 au. These findings are consistent with a scenario in which the initial multiplicity properties, set by the star formation process itself, are identical in the ONC and in other SFRs and subsequently altered by the cluster's dynamical evolution. This implies that the fragmentation process does not depend on the global properties of a molecular cloud, but on the local properties of prestellar cores, and that the latter are self-regulated to be nearly identical in a wide range of environments. These results, however, raise anew the question of the origin of field stars as the tight binaries we have discovered will not be destroyed as the ONC dissolves into the galactic field. It thus appears that most field stars formed in regions that differ from well-studied SFRs in the Solar neighborhood, possibly due to changes in core fragmentation on Gyr timescales.

Interactions between multiple supermassive black holes in galactic nuclei: a solution to the final parsec problem

NASA Astrophysics Data System (ADS)

Ryu, Taeho; Perna, Rosalba; Haiman, Zoltán; Ostriker, Jeremiah P.; Stone, Nicholas C.

2018-01-01

Using few-body simulations, we investigate the evolution of supermassive black holes (SMBHs) in galaxies (M* = 1010-1012 M⊙ at z = 0) at 0 < z < 4. Following galaxy merger trees from the Millennium simulation, we model BH mergers with two extreme binary decay scenarios for the 'hard binary' stage: a full or an empty loss cone. These two models should bracket the true evolution, and allow us to separately explore the role of dynamical friction and that of multibody BH interactions on BH mergers. Using the computed merger rates, we infer the stochastic gravitational wave background (GWB). Our dynamical approach is a first attempt to study the dynamical evolution of multiple SMBHs in the host galaxies undergoing mergers with various mass ratios (10-4 < q* < 1). Our main result demonstrates that SMBH binaries are able to merge in both scenarios. In the empty loss cone case, we find that BHs merge via multibody interactions, avoiding the 'final parsec' problem, and entering the pulsar timing arrays band with substantial orbital eccentricity. Our full loss cone treatment, albeit more approximate, suggests that the eccentricity becomes even higher when GWs become dominant, leading to rapid coalescences (binary lifetime ≲1 Gyr). Despite the lower merger rates in the empty loss cone case, due to their higher mass ratios and lower redshifts, the GWB in the full/empty loss cone models are comparable (0.70 × 10-15 and 0.53 × 10-15 at a frequency of 1 yr-1, respectively). Finally, we compute the effects of high eccentricities on the GWB spectrum.

4-D Imaging and Modeling of Eta Carinae's Inner Fossil Wind Structures

NASA Astrophysics Data System (ADS)

Madura, Thomas I.; Gull, Theodore; Teodoro, Mairan; Clementel, Nicola; Corcoran, Michael; Damineli, Augusto; Groh, Jose; Hamaguchi, Kenji; Hillier, D. John; Moffat, Anthony; Richardson, Noel; Weigelt, Gerd; Lindler, Don; Feggans, Keith

2017-11-01

Eta Carinae is the most massive active binary within 10,000 light-years and is famous for the largest non-terminal stellar explosion ever recorded. Observations reveal that the supermassive (~120 M⊙) binary, consisting of an LBV and either a WR or extreme O star, undergoes dramatic changes every 5.54 years due to the stars' very eccentric orbits (e ~ 0.9). Many of these changes are caused by a dynamic wind-wind collision region (WWCR) between the stars, plus expanding fossil WWCRs formed one, two, and three 5.54-year cycles ago. The fossil WWCRs can be spatially and spectrally resolved by the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS). Starting in June 2009, we used the HST/STIS to spatially map Eta Carinae's fossil WWCRs across one full orbit, following temporal changes in several forbidden emission lines (e.g. [Feiii] 4659 Å, [Feii] 4815 Å), creating detailed data cubes at multiple epochs. Multiple wind structures were imaged, revealing details about the binary's orbital motion, photoionization properties, and recent (~5 - 15 year) mass-loss history. These observations allow us to test 3-D hydrodynamical and radiative-transfer models of the interacting winds. Our observations and models strongly suggest that the wind and photoionization properties of Eta Carinae's binary have not changed substantially over the past several orbital cycles. They also provide a baseline for following future changes in Eta Carinae, essential for understanding the late-stage evolution of this nearby supernova progenitor. For more details, see Gull et al. (2016) and references therein.

A Fast EM Algorithm for Fitting Joint Models of a Binary Response and Multiple Longitudinal Covariates Subject to Detection Limits

PubMed Central

Bernhardt, Paul W.; Zhang, Daowen; Wang, Huixia Judy

2014-01-01

Joint modeling techniques have become a popular strategy for studying the association between a response and one or more longitudinal covariates. Motivated by the GenIMS study, where it is of interest to model the event of survival using censored longitudinal biomarkers, a joint model is proposed for describing the relationship between a binary outcome and multiple longitudinal covariates subject to detection limits. A fast, approximate EM algorithm is developed that reduces the dimension of integration in the E-step of the algorithm to one, regardless of the number of random effects in the joint model. Numerical studies demonstrate that the proposed approximate EM algorithm leads to satisfactory parameter and variance estimates in situations with and without censoring on the longitudinal covariates. The approximate EM algorithm is applied to analyze the GenIMS data set. PMID:25598564

VizieR Online Data Catalog: Massive stars in 30 Dor (Schneider+, 2018)

NASA Astrophysics Data System (ADS)

Schneider, F. R. N.; Sana, H.; Evans, C. J.; Bestenlehner, J. M.; Castro, N.; Fossati, L.; Grafener, G.; Langer, N.; Ramirez-Agudelo, O. H.; Sabin-Sanjulian, C.; Simon-Diaz, S.; Tramper, F.; Crowther, P. A.; de Koter, A.; de Mink, S. E.; Dufton, P. L.; Garcia, M.; Gieles, M.; Henault-Brunet, V.; Herrero, A.; Izzard, R. G.; Kalari, V.; Lennon, D. J.; Apellaniz, J. M.; Markova, N.; Najarro, F.; Podsiadlowski, P.; Puls, J.; Taylor, W. D.; van Loon, J. T.; Vink, J. S.; Norman, C.

2018-02-01

Through the use of the Fibre Large Array Multi Element Spectrograph (FLAMES) on the Very Large Telescope (VLT), the VLT-FLAMES Tarantula Survey (VFTS) has obtained optical spectra of ~800 massive stars in 30 Dor, avoiding the core region of the dense star cluster R136 because of difficulties with crowding. Repeated observations at multiple epochs allow determination of the orbital motion of potentially binary objects. For a sample of 452 apparently single stars, robust stellar parameters-such as effective temperatures, luminosities, surface gravities, and projected rotational velocities-are determined by modeling the observed spectra. Composite spectra of visual multiple systems and spectroscopic binaries are not considered here because their parameters cannot be reliably inferred from the VFTS data. To match the derived atmospheric parameters of the apparently single VFTS stars to stellar evolutionary models, we use the Bayesian code Bonnsai. (2 data files).

Analysis of factors influencing organic fruit and vegetable purchasing in Istanbul, Turkey.

PubMed

Oraman, Yasemin; Unakitan, Gökhan

2010-01-01

This article examines the influences on the purchasing decisions of fruit and vegetable consumers and presents findings from a survey conducted with 385 respondents living in urban areas in Istanbul, Turkey. It uses a binary logistic model to estimate factor effects in organic fruit and vegetable purchasing in Turkey. The results indicate that concern for human health and safety is a key factor that influences consumer preferences for organic food. Findings will help organic product suppliers understand the key factors influencing consumer purchasing and consumption behaviors.

Iron K lines from low-mass X-ray binaries

NASA Technical Reports Server (NTRS)

Kallman, T.; White, N. E.

1989-01-01

Models are presented for the 6-7 keV iron line emission from low-mass X-ray binaries. A simplified model for an accretion disk corona is used to examine the dependence of the observable line properties, line width and mean energy, on the radial distance of the emission region from the X-ray source, and on the fraction of the X-rays from the source which reach the disk surface. The effects of blending of multiple line components and of Comptonization of the line profile are included in numerical calculations of the emitted profile shape. The results of these calculations, when compared with the line properties observed from several low-mass X-ray binaries, suggest that the broadening is dominated either by rotation or by Compton scattering through a greater optical depth than is expected from an accretion disk corona.

Advances in Black-Hole Mergers: Spins and Unequal Masses

NASA Technical Reports Server (NTRS)

Kelly, Bernard

2007-01-01

The last two years have seen incredible development in numerical relativity: from fractions of an orbit, evolutions of an equal-mass binary have reached multiple orbits, and convergent gravitational waveforms have been produced from several research groups and numerical codes. We are now able to move our attention from pure numerics to astrophysics, and address scenarios relevant to current and future gravitational-wave detectors.Over the last 12 months at NASA Goddard, we have extended the accuracy of our Hahn-Dol code, and used it to move toward these goals. We have achieved high-accuracy simulations of black-hole binaries of low initial eccentricity, with enough orbits of inspiral before merger to allow us to produce hybrid waveforms that reflect accurately the entire lifetime of the BH binary. We are extending this work, looking at the effects of unequal masses and spins.

Bit-Table Based Biclustering and Frequent Closed Itemset Mining in High-Dimensional Binary Data

PubMed Central

Király, András; Abonyi, János

2014-01-01

During the last decade various algorithms have been developed and proposed for discovering overlapping clusters in high-dimensional data. The two most prominent application fields in this research, proposed independently, are frequent itemset mining (developed for market basket data) and biclustering (applied to gene expression data analysis). The common limitation of both methodologies is the limited applicability for very large binary data sets. In this paper we propose a novel and efficient method to find both frequent closed itemsets and biclusters in high-dimensional binary data. The method is based on simple but very powerful matrix and vector multiplication approaches that ensure that all patterns can be discovered in a fast manner. The proposed algorithm has been implemented in the commonly used MATLAB environment and freely available for researchers. PMID:24616651

Measuring In-Plane Displacements with Variable Sensitivity Using Diffractive Optic Interferometry

NASA Technical Reports Server (NTRS)

Shepherd, Robert L.; Gilbert, John A.; Cole, Helen J.; Ashley, Paul R.

1998-01-01

This paper introduces a method called diffractive optic interferometry (DOI) which allows in-plane displacement components to be measured with variable sensitivity. DOI relies on binary optical elements fabricated as phase-type Dammann gratings which produce multiple diffraction orders of nearly equal intensity. Sensitivity is varied by combining the different wavefronts produced by a conjugate pair of these binary optical elements; a transmission element is used to produce several illumination beams while a reflective element, replicated on the surface of a specimen, provides the reference for the undeformed state. The steps taken to design and fabricate these binary optical elements are described. The specimen grating is characterized, and tested on a disk subjected to diametrical compression. Overall, the results are excellent, with experimental data agreeing to within a few percent of the theoretical predictions.

The Formation and Gravitational-wave Detection of Massive Stellar Black Hole Binaries

NASA Astrophysics Data System (ADS)

Belczynski, Krzysztof; Buonanno, Alessandra; Cantiello, Matteo; Fryer, Chris L.; Holz, Daniel E.; Mandel, Ilya; Miller, M. Coleman; Walczak, Marek

2014-07-01

If binaries consisting of two ~100 M ⊙ black holes exist, they would serve as extraordinarily powerful gravitational-wave sources, detectable to redshifts of z ~ 2 with the advanced LIGO/Virgo ground-based detectors. Large uncertainties about the evolution of massive stars preclude definitive rate predictions for mergers of these massive black holes. We show that rates as high as hundreds of detections per year, or as low as no detections whatsoever, are both possible. It was thought that the only way to produce these massive binaries was via dynamical interactions in dense stellar systems. This view has been challenged by the recent discovery of several >~ 150 M ⊙ stars in the R136 region of the Large Magellanic Cloud. Current models predict that when stars of this mass leave the main sequence, their expansion is insufficient to allow common envelope evolution to efficiently reduce the orbital separation. The resulting black hole-black hole binary remains too wide to be able to coalesce within a Hubble time. If this assessment is correct, isolated very massive binaries do not evolve to be gravitational-wave sources. However, other formation channels exist. For example, the high multiplicity of massive stars, and their common formation in relatively dense stellar associations, opens up dynamical channels for massive black hole mergers (e.g., via Kozai cycles or repeated binary-single interactions). We identify key physical factors that shape the population of very massive black hole-black hole binaries. Advanced gravitational-wave detectors will provide important constraints on the formation and evolution of very massive stars.

Hydrodynamical simulations of the tidal stripping of binary stars by massive black holes

NASA Astrophysics Data System (ADS)

Mainetti, Deborah; Lupi, Alessandro; Campana, Sergio; Colpi, Monica

2016-04-01

In a galactic nucleus, a star on a low angular momentum orbit around the central massive black hole can be fully or partially disrupted by the black hole tidal field, lighting up the compact object via gas accretion. This phenomenon can repeat if the star, not fully disrupted, is on a closed orbit. Because of the multiplicity of stars in binary systems, also binary stars may experience in pairs such a fate, immediately after being tidally separated. The consumption of both the binary components by the black hole is expected to power a double-peaked flare. In this paper, we perform for the first time, with GADGET2, a suite of smoothed particle hydrodynamics simulations of binary stars around a galactic central black hole in the Newtonian regime. We show that accretion luminosity light curves from double tidal disruptions reveal a more prominent knee, rather than a double peak, when decreasing the impact parameter of the encounter and when elevating the difference between the mass of the star which leaves the system after binary separation and the mass of the companion. The detection of a knee can anticipate the onset of periodic accretion luminosity flares if one of the stars, only partially disrupted, remains bound to the black hole after binary separation. Thus knees could be precursors of periodic flares, which can then be predicted, followed up and better modelled. Analytical estimates in the black hole mass range 105-108 M⊙ show that the knee signature is enhanced in the case of black holes of mass 106-107 M⊙.

Discovery and characterization of 3000+ main-sequence binaries from APOGEE spectra

NASA Astrophysics Data System (ADS)

El-Badry, Kareem; Ting, Yuan-Sen; Rix, Hans-Walter; Quataert, Eliot; Weisz, Daniel R.; Cargile, Phillip; Conroy, Charlie; Hogg, David W.; Bergemann, Maria; Liu, Chao

2018-05-01

We develop a data-driven spectral model for identifying and characterizing spatially unresolved multiple-star systems and apply it to APOGEE DR13 spectra of main-sequence stars. Binaries and triples are identified as targets whose spectra can be significantly better fit by a superposition of two or three model spectra, drawn from the same isochrone, than any single-star model. From an initial sample of ˜20 000 main-sequence targets, we identify ˜2500 binaries in which both the primary and secondary stars contribute detectably to the spectrum, simultaneously fitting for the velocities and stellar parameters of both components. We additionally identify and fit ˜200 triple systems, as well as ˜700 velocity-variable systems in which the secondary does not contribute detectably to the spectrum. Our model simplifies the process of simultaneously fitting single- or multi-epoch spectra with composite models and does not depend on a velocity offset between the two components of a binary, making it sensitive to traditionally undetectable systems with periods of hundreds or thousands of years. In agreement with conventional expectations, almost all the spectrally identified binaries with measured parallaxes fall above the main sequence in the colour-magnitude diagram. We find excellent agreement between spectrally and dynamically inferred mass ratios for the ˜600 binaries in which a dynamical mass ratio can be measured from multi-epoch radial velocities. We obtain full orbital solutions for 64 systems, including 14 close binaries within hierarchical triples. We make available catalogues of stellar parameters, abundances, mass ratios, and orbital parameters.

Sub-1% accuracy in fundamental stellar parameters from triply eclipsing systems

NASA Astrophysics Data System (ADS)

Prsa, Andrej

The current state-of-the-art level of accuracy in fundamental stellar parameters from eclipsing binary stars is 2-3%. Here we propose to use eclipsing triple stars to reduce the error bars by an entire order of magnitude, i.e. to 0.2-0.3%. This can be done because a presence of the third component breaks most of the degeneracy inherent in binary systems between the inclination and stellar sizes. We detail the feasibility arguments and foresee that these results will provide exceptional benchmark objects for stringent tests of stellar evolution and population models. The formation channel of close binary stars (with separations of several stellar radii) is a matter of debate. It is clear that close binaries cannot form in situ because (1) the physical radius of a star shrinks by a large factor between birth and the main sequence, yet many main-sequence stars have companions orbiting at a distance of only a few stellar radii, and (2) in current theories of planet formation, the region within 0.1 AU of a protostar is too hot and rarefied for a Jupiter-mass planet to form, yet many hot jupiters are observed at such distances. Current theories of dynamic orbital evolution attribute orbital shrinking to Kozai cycles and tidal friction, which are long-lasting, perturbative effects that take Gyrs to shrink orbits by 1-2 orders of magnitude. This implies that, if a binary star system has a tertiary companion, it will be in a hierarchical structure, and any disruptive orbital encounters should be exceedingly rare after a certain period. The Kepler satellite observed continuously over 2800 eclipsing binary stars over 4 years of its mission lifetime. The ultra-high precision photometry and essentially uninterrupted time coverage enables us to time the eclipses to a 6 second precision. Because of the well understood physics that governs the orbital motion of two bodies around the center of mass, the expected times of eclipses can be predicted to a fraction of a second. When other physical processes interplay, such as apsidal motion, mass transfer or third body interactions, the times of eclipses deviate from predictions: they either come early or late. These deviations are called eclipse timing variations (ETVs) and can range from a few seconds to a few hours. Our team measured ETVs for the entire Kepler data-set of eclipsing binaries and found 516 that demonstrate significant deviations. Of those, 16 show strong interactions between the binary system and the tertiary component that significantly affects the binary orbit within a single encounter. This observed rate of dynamical perturbation events is unexpectedly high and at odds with current theories. We propose to study these objects in great detail: (1) to apply a developed photodynamical code to model multiple body interactions; (2) to fully solve orbital dynamics of these interacting bodies using all available Kepler data, deriving masses of all objects to better than 1%; (3) to measure the occurrence rate of strong orbital interactions in multiple systems and compare it to the predicted rates; (4) to hypothesize and simulate additional evolution channels that could potentially lead to such a high occurrence rate of disruptive events; and (5) to integrate these systems over time and test whether this dynamic evolution can cause efficient orbital tightening and the creation of short period binaries. The team consists of a PI who has experience with Kepler satellite's idiosyncrasies, two postdoctoral fellows, one graduate student, and six undergraduate students that will invest their summer months to learn about multiple body interactions. The proposed study has far-reaching research goals in stellar and planetary science astrophysics, a strong educational/training component and is aligned with NASA's objectives as outlined in the NRA call. Kepler is the only instrument that can provide the accuracy and temporal coverage required for the execution of this project.

CARMENES input catalogue of M dwarfs. II. High-resolution imaging with FastCam

NASA Astrophysics Data System (ADS)

Cortés-Contreras, M.; Béjar, V. J. S.; Caballero, J. A.; Gauza, B.; Montes, D.; Alonso-Floriano, F. J.; Jeffers, S. V.; Morales, J. C.; Reiners, A.; Ribas, I.; Schöfer, P.; Quirrenbach, A.; Amado, P. J.; Mundt, R.; Seifert, W.

2017-01-01

Aims: We search for low-mass companions of M dwarfs and characterize their multiplicity fraction with the purpose of helping in the selection of the most appropriate targets for the CARMENES exoplanet survey. Methods: We obtained high-resolution images in the I band with the lucky imaging instrument FastCam at the 1.5 m Telescopio Carlos Sánchez for 490 mid- to late-M dwarfs. For all the detected binaries, we measured angular separations, position angles, and magnitude differences in the I band. We also calculated the masses of each individual component and estimated orbital periods, using the available magnitude and colour relations for M dwarfs and our own MJ-spectral type and mass-MI relations. To avoid biases in our sample selection, we built a volume-limited sample of M0.0-M5.0 dwarfs that is complete up to 86% within 14 pc. Results: From the 490 observed stars, we detected 80 companions in 76 systems, of which 30 are new discoveries. Another six companion candidates require additional astrometry to confirm physical binding. The multiplicity fraction in our observed sample is 16.7 ± 2.0%. The bias-corrected multiplicity fraction in our volume-limited sample is 19.5 ± 2.3% for angular separations of 0.2 to 5.0 arcsec (1.4-65.6 au), with a peak in the distribution of the projected physical separations at 2.5-7.5 au. For M0.0-M3.5 V primaries, our search is sensitive to mass ratios higher than 0.3 and there is a higher density of pairs with mass ratios over 0.8 compared to those at lower mass ratios. Binaries with projected physical separations shorter than 50 au also tend to be of equal mass. For 26 of our systems, we estimated orbital periods shorter than 50 a, 10 of which are presented here for the first time. We measured variations in angular separation and position angle that are due to orbital motions in 17 of these systems. The contribution of binaries and multiples with angular separations shorter than 0.2 arcsec, longer than 5.0 arcsec, and of spectroscopic binaries identified from previous searches, although not complete, may increase the multiplicity fraction of M dwarfs in our volume-limited sample to at least 36%. Tables A.1-A.6 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/597/A47

How I Learned to Stop Worrying and Love Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Moe, Maxwell Cassady

Relatively massive B-type stars with closely orbiting stellar companions can evolve to produce Type Ia supernovae, X-ray binaries, millisecond pulsars, mergers of neutron stars, gamma ray bursts, and sources of gravitational waves. However, the formation mechanism, intrinsic frequency, and evolutionary processes of B-type binaries are poorly understood. As of 2012, the binary statistics of massive stars had not been measured at low metallicities, extreme mass ratios, or intermediate orbital periods. This thesis utilizes large data sets of eclipsing binaries to measure the physical properties of B-type binaries in these previously unexplored portions of the parameter space. The updated binary statistics provide invaluable insight into the formation of massive stars and binaries as well as reliable initial conditions for population synthesis studies of binary star evolution. We first compare the properties of B-type eclipsing binaries in our Milky Way Galaxy and the nearby Magellanic Cloud Galaxies. We model the eclipsing binary light curves and perform detailed Monte Carlo simulations to recover the intrinsic properties and distributions of the close binary population. We find the frequency, period distribution, and mass-ratio distribution of close B-type binaries do not significantly depend on metallicity or environment. These results indicate the formation of massive binaries are relatively insensitive to their chemical abundances or immediate surroundings. Second, we search for low-mass eclipsing companions to massive B-type stars in the Large Magellanic Cloud Galaxy. In addition to finding such extreme mass-ratio binaries, we serendipitously discover a new class of eclipsing binaries. Each system comprises a massive B-type star that is fully formed and a nascent low-mass companion that is still contracting toward its normal phase of evolution. The large low-mass secondaries discernibly reflect much of the light they intercept from the hot B-type stars, thereby producing sinusoidal variations in perceived brightness as they orbit. These nascent eclipsing binaries are embedded in the hearts of star-forming emission nebulae, and therefore provide a unique snapshot into the formation and evolution of massive binaries and stellar nurseries. We next examine a large sample of B-type eclipsing binaries with intermediate orbital periods. To achieve such a task, we develop an automated pipeline to classify the eclipsing binaries, measure their physical properties from the observed light curves, and recover the intrinsic binary statistics by correcting for selection effects. We find the population of massive binaries at intermediate separations differ from those orbiting in close proximity. Close massive binaries favor small eccentricities and have correlated component masses, demonstrating they coevolved via competitive accretion during their formation in the circumbinary disk. Meanwhile, B-type binaries at slightly wider separations are born with large eccentricities and are weighted toward extreme mass ratios, indicating the components formed relatively independently and subsequently evolved to their current configurations via dynamical interactions. By using eclipsing binaries as accurate age indicators, we also reveal that the binary orbital eccentricities and the line-of-sight dust extinctions are anticorrelated with respect to time. These empirical relations provide robust constraints for tidal evolution in massive binaries and the evolution of the dust content in their surrounding environments. Finally, we compile observations of early-type binaries identified via spectroscopy, eclipses, long-baseline interferometry, adaptive optics, lucky imaging, high-contrast photometry, and common proper motion. We combine the samples from the various surveys and correct for their respective selection effects to determine a comprehensive nature of the intrinsic binary statistics of massive stars. We find the probability distributions of primary mass, secondary mass, orbital period, and orbital eccentricity are all interrelated. These updated multiplicity statistics imply a greater frequency of low-mass X-ray binaries, millisecond pulsars, and Type Ia supernovae than previously predicted.

The RECONS Hunt for Intriguing Binaries in the Solar Neighborhood

NASA Astrophysics Data System (ADS)

Bean, J. L.; Henry, T. J.; Jao, W. C.; Subasavage, J. P.

2001-12-01

As part of an effort to characterize the Sun's neighbors, photometric research was carried out on two samples of low-mass stars known or suspected to lie within 25 parsecs of the Sun. Quality filtered optical photometric data (UBVRI) from published research were merged with recently released infrared data (JHK) from the Two Micron All Sky Survey (2MASS) to create comprehensive long baseline V-I or V-K colors for more than 1400 stars. These were then combined with parallaxes from the NStars Database to create color-absolute magnitude diagrams. The results of this research include increasing the breadth of the NStars Database by adding photometric data for over 1400 stars, and identifying intriguing multiple systems (close spectroscopic binaries, BY Dra types, RS CVn systems) as well as white dwarfs and evolved stars in the solar neighborhood. More than two dozen objects have been identified as probable new multiple systems from their positions above the main sequence. Additional investigations for these intriguing systems are planned, including observations made with the GSU CHARA Array to resolve very close binary systems. This research is a continuation of the work done by RECONS (Research Consortium on Nearby Stars) based at Georgia Sate U., Johns Hopkins U., and U. Virginia, and NASA's Nearby Stars Project (NStars).

WISE Brown Dwarf Binaries: The Discovery of a T5+T5 and a T8.5+T9 System

NASA Astrophysics Data System (ADS)

Gelino, Christopher R.; Kirkpatrick, J. Davy; Cushing, Michael C.; Eisenhardt, Peter R.; Griffith, Roger L.; Mainzer, Amanda K.; Marsh, Kenneth A.; Skrutskie, Michael F.; Wright, Edward L.

2011-08-01

The multiplicity properties of brown dwarfs are critical empirical constraints for formation theories, while multiples themselves provide unique opportunities to test evolutionary and atmospheric models and examine empirical trends. Studies using high-resolution imaging cannot only uncover faint companions, but they can also be used to determine dynamical masses through long-term monitoring of binary systems. We have begun a search for the coolest brown dwarfs using preliminary processing of data from the Wide-field Infrared Survey Explorer and have confirmed many of the candidates as late-type T dwarfs. In order to search for companions to these objects, we are conducting observations using the Laser Guide Star Adaptive Optics system on Keck II. Here we present the first results of that search, including a T5 binary with nearly equal mass components and a faint companion to a T8.5 dwarf with an estimated spectral type of T9. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Matter effects on binary neutron star waveforms

NASA Astrophysics Data System (ADS)

Read, Jocelyn S.; Baiotti, Luca; Creighton, Jolien D. E.; Friedman, John L.; Giacomazzo, Bruno; Kyutoku, Koutarou; Markakis, Charalampos; Rezzolla, Luciano; Shibata, Masaru; Taniguchi, Keisuke

2013-08-01

Using an extended set of equations of state and a multiple-group multiple-code collaborative effort to generate waveforms, we improve numerical-relativity-based data-analysis estimates of the measurability of matter effects in neutron-star binaries. We vary two parameters of a parametrized piecewise-polytropic equation of state (EOS) to analyze the measurability of EOS properties, via a parameter Λ that characterizes the quadrupole deformability of an isolated neutron star. We find that, to within the accuracy of the simulations, the departure of the waveform from point-particle (or spinless double black-hole binary) inspiral increases monotonically with Λ and changes in the EOS that did not change Λ are not measurable. We estimate with two methods the minimal and expected measurability of Λ in second- and third-generation gravitational-wave detectors. The first estimate using numerical waveforms alone shows that two EOSs which vary in radius by 1.3 km are distinguishable in mergers at 100 Mpc. The second estimate relies on the construction of hybrid waveforms by matching to post-Newtonian inspiral and estimates that the same EOSs are distinguishable in mergers at 300 Mpc. We calculate systematic errors arising from numerical uncertainties and hybrid construction, and we estimate the frequency at which such effects would interfere with template-based searches.

Blue straggler formation at core collapse

NASA Astrophysics Data System (ADS)

Banerjee, Sambaran

Among the most striking feature of blue straggler stars (BSS) in globular clusters is the presence of multiple sequences of BSSs in the colour-magnitude diagrams (CMDs) of several globular clusters. It is often envisaged that such a multiple BSS sequence would arise due a recent core collapse of the host cluster, triggering a number of stellar collisions and binary mass transfers simultaneously over a brief episode of time. Here we examine this scenario using direct N-body computations of moderately-massive star clusters (of order 104 {M⊙). As a preliminary attempt, these models are initiated with ≈8-10 Gyr old stellar population and King profiles of high concentrations, being ``tuned'' to undergo core collapse quickly. BSSs are indeed found to form in a ``burst'' at the onset of the core collapse and several of such BS-bursts occur during the post-core-collapse phase. In those models that include a few percent primordial binaries, both collisional and binary BSSs form after the onset of the (near) core-collapse. However, there is as such no clear discrimination between the two types of BSSs in the corresponding computed CMDs. We note that this may be due to the less number of BSSs formed in these less massive models than that in actual globular clusters.

London Measure of Unplanned Pregnancy: guidance for its use as an outcome measure

PubMed Central

Hall, Jennifer A; Barrett, Geraldine; Copas, Andrew; Stephenson, Judith

2017-01-01

Background The London Measure of Unplanned Pregnancy (LMUP) is a psychometrically validated measure of the degree of intention of a current or recent pregnancy. The LMUP is increasingly being used worldwide, and can be used to evaluate family planning or preconception care programs. However, beyond recommending the use of the full LMUP scale, there is no published guidance on how to use the LMUP as an outcome measure. Ordinal logistic regression has been recommended informally, but studies published to date have all used binary logistic regression and dichotomized the scale at different cut points. There is thus a need for evidence-based guidance to provide a standardized methodology for multivariate analysis and to enable comparison of results. This paper makes recommendations for the regression method for analysis of the LMUP as an outcome measure. Materials and methods Data collected from 4,244 pregnant women in Malawi were used to compare five regression methods: linear, logistic with two cut points, and ordinal logistic with either the full or grouped LMUP score. The recommendations were then tested on the original UK LMUP data. Results There were small but no important differences in the findings across the regression models. Logistic regression resulted in the largest loss of information, and assumptions were violated for the linear and ordinal logistic regression. Consequently, robust standard errors were used for linear regression and a partial proportional odds ordinal logistic regression model attempted. The latter could only be fitted for grouped LMUP score. Conclusion We recommend the linear regression model with robust standard errors to make full use of the LMUP score when analyzed as an outcome measure. Ordinal logistic regression could be considered, but a partial proportional odds model with grouped LMUP score may be required. Logistic regression is the least-favored option, due to the loss of information. For logistic regression, the cut point for un/planned pregnancy should be between nine and ten. These recommendations will standardize the analysis of LMUP data and enhance comparability of results across studies. PMID:28435343

Agreeableness and pregnancy: Relations with coping and psychiatric symptoms, a longitudinal study on Spanish pregnant women.

PubMed

Peñacoba, Cecilia; Rodríguez, Laura; Carmona, Javier; Marín, Dolores

2018-02-01

Agreeableness is associated with good mental health during pregnancy. Although different studies have indicated that agreeableness is related to adaptive coping, this relation has scarcely been studied in pregnant women. The aim of this study was to analyze the possible differences between high and low agreeableness in relation to coping strategies and psychiatric symptoms in pregnant women. We conducted a longitudinal prospective study between October 2009 and January 2013. Pregnant women (n = 285) were assessed in the first trimester of pregnancy, and 122 of them were assessed during the third. Data were collected using the Coping Strategies Questionnaire, the Symptom Check List 90-R, and the agreeableness subscale of the NEO-FFI. Using the SPSS 21 statistics package, binary logistic regression, two-way mixed analysis of variance, and multiple regression analyses and a Sobel test were conducted. Higher levels of agreeableness were associated with positive reappraisal and problem-solving, and lower levels of agreeableness were associated with overt emotional expression and negative self-focused coping. Women with low agreeableness had poorer mental health, especially in the first trimester. These findings should be taken into account to improve women's experiences during pregnancy. Nevertheless, given the scarcity of data, additional studies are needed.

Contribution of primary care to health: an individual level analysis from Tibet, China.

PubMed

Wang, Wenhua; Shi, Leiyu; Yin, Aitian; Mao, Zongfu; Maitland, Elizabeth; Nicholas, Stephen; Liu, Xiaoyun

2015-11-30

There have been significant improvements in health outcomes in Tibet, health disparities between Tibet and the rest of China has been greatly reduced. This paper tests whether there was a positive association between good primary care and better health outcomes in Tibet. A validated Tibetan version of the Primary Care Assessment Tool (PCAT-T) was used to collect data on 1386 patients aged over 18 years old accessing primary care. Self-rated health (SRH) was employed to measure health outcomes. A multiple binary logistic regression model was used to explore the association between primary care quality and self-rated health status after controlling for socio-demographic and lifestyle variables. This study found that primary care quality had a significant positive association with self-rated health status. Among the nine domains of PCAT-T, family centeredness domain had the highest Odds Ratio (OR = 1.013) with SRH. Patients located in rural area, with higher education levels, without depression, and less frequent drinking were more likely to self-rate as "good health" compared with the reference group. In Tibet, higher quality primary care was associated with better self-rated health status. Primary care should be much strengthened in future health system reform in Tibet.

The relationship between lifestyle factors and clinical symptoms of bipolar disorder patients in a Chinese population.

PubMed

Huang, Jia; Yuan, Cheng Mei; Xu, Xian Rong; Wang, Yong; Hong, Wu; Wang, Zuo Wei; Su, You Song; Hu, Ying Yan; Cao, Lan; Wang, Yu; Chen, Jun; Fang, Yi Ru

2018-05-06

There is evidence that bipolar disorder (BD) patients with an unhealthy lifestyle have a worse course of illness. This study was designed to examine the extent to which lifestyle could influence the severity of clinical symptoms associated with BD. A total of 113 BD patients were recruited in this study. The lifestyle information including data on dietary patterns, physical activity, and sleep quality were collected using a self-rated questionnaire. The results showed that the consumption of whole grain, seafood, and dairy products were significantly negatively correlated with the 17-item Hamilton Rating Scale for Depression (HAMD-17) total score. The consumption of sugar, soft drinks, and alcohol as well as being a current smoker were positively correlated with the severity of clinical symptoms. Multiple linear regression and binary logistic regression analyses demonstrated an independent negative correlation between both whole grain and dairy product consumption with the HAMD-17 score. The results from the current study suggested that lifestyle factors, especially dietary patterns, might be associated with clinical symptoms of BD. The association between the consumption of specific foods and severity of depressive symptoms may offer some useful information and further understanding of the role of lifestyle factors in the development of BD. Copyright © 2018. Published by Elsevier B.V.

Relationship between Dietary Fat Intake, Its Major Food Sources and Assisted Reproduction Parameters

PubMed Central

Kazemi, Ashraf; Ramezanzadeh, Fatemeh; Nasr-Esfahani, Mohammad Hosein

2014-01-01

Background High dietary fat consumption may alter oocyte development and embryonic development. This prospective study was conducted to determine the relation between dietary fat consumption level, its food sources and the assisted reproduction parameters. Methods A prospective study was conducted on 240 infertile women. In assisted reproduction treatment cycle, fat consumption and major food sources over the previous three months were identified. The number of retrieved oocytes, metaphase ΙΙ stage oocytes numbers, fertilization rate, embryo quality and clinical pregnancy rate were also determined. The data were analyzed using multiple regression, binary logistic regression, chi-square and t-test. The p-value of less than 0.05 was considered significant. Results Total fat intake adjusted for age, body mass index, physical activity and etiology of infertility was positively associated with the number of retrieved oocytes and inversely associated with the high embryo quality rate. An inverse association was observed between sausage and turkey ham intake and the number of retrieved oocytes. Also, oil intake level had an inverse association with good cleavage rate. Conclusion The results revealed that higher levels of fat consumption tend to increase the number of retrieved oocytes and were adversely related to embryonic development. Among food sources of fat, vegetable oil, sausage and turkey ham intake may adversely affect assisted reproduction parameters. PMID:25473630

Obesity Increases Prevalence of Colonic Adenomas at Screening Colonoscopy: A Canadian Community-Based Study

PubMed Central

Chen, Grant I.; Devlin, Tim; Gibbs, Alison; Murray, Iain C.; Tran, Stanley; Weigensberg, Corey

2017-01-01

Background and Aims Obesity is a risk factor for colorectal neoplasia. We examined the influence of obesity and metabolic syndrome (MetS) on prevalence of neoplasia at screening colonoscopy. Methods We evaluated 2020 subjects undergoing first screening colonoscopy. Body mass index (BMI) was calculated at enrolment. Hyperlipidemia (HL), hypertension (HT), and diabetes mellitus (DM) were identified. Details of colonoscopy, polypectomy, and histology were recorded. Odds for adenomas (A) and advanced adenomas (ADV) in overweight (BMI 25.1–30) and obese (BMI > 30) subjects were assessed by multinomial regression, adjusted for covariates. Analyses included relationships between HL, HT, DM, age, tobacco usage, and neoplasia. Discriminatory power of HT, HL, DM, and BMI for neoplasia was assessed by binary logistic regression. Odds were calculated for neoplasia in each colonic segment related to BMI. Results A and ADV were commoner in overweight and obese males, obese females, older subjects, and smokers. HL, HT, and DM were associated with increased odds for neoplasia, significantly for A with hypertension. BMI alone predicted neoplasia as well as HT, HL, DM, or combinations thereof. All segments of the colon were affected. Multiple polyps were particularly prevalent in the obese. Conclusions Obesity and MetS are risk factors for colonic neoplasia in a Canadian population. PMID:28781966

A multicenter study on the audiometric findings of styrene-exposed workers.

PubMed

Morata, Thais C; Sliwinska-Kowalska, Mariola; Johnson, Ann-Christin; Starck, Jukka; Pawlas, Krystyna; Zamyslowska-Szmytke, Ewa; Nylen, Per; Toppila, Esko; Krieg, Edward; Pawlas, Natalia; Prasher, Deepak

2011-10-01

The objective of this study was to evaluate hearing loss among workers exposed to styrene, alone or with noise. This cross-sectional study was conducted as part of NoiseChem, a European Commission 5th Framework Programme research project, by occupational health institutes in Finland, Sweden, and Poland. Participants' ages ranged from 18-72 years (n = 1620 workers). Participants exposed to styrene, alone or with noise, were from reinforced fiberglass products manufacturing plants (n = 862). Comparison groups were comprised of workers noise-exposed (n = 400) or controls (n = 358). Current styrene exposures ranged from 0 to 309 mg/m(3), while mean current noise levels ranged from 70-84 dB(A). Hearing thresholds of styrene-exposed participants were compared with Annexes A and B from ANSI S3.44, 1996. The audiometric thresholds of styrene exposed workers were significantly poorer than those in published standards. Age, gender, and styrene exposure met the significance level criterion in the multiple logistic regression for the binary outcome 'hearing loss' (P = 0.0000). Exposure to noise (<85 dBA p = 0.0001; ≥85 dB(A) p = 0.0192) interacted significantly with styrene exposure. Occupational exposure to styrene is a risk factor for hearing loss, and styrene-exposed workers should be included in hearing loss prevention programs.

Access to continued-use medication among older adults, Brazil

PubMed Central

Viana, Karynna Pimentel; Brito, Alexandre dos Santos; Rodrigues, Claudia Soares; Luiz, Ronir Raggio

2015-01-01

OBJECTIVE To determine the prevalence and associated access factors for all continued-use prescription drugs and the ways in which they can be obtained. METHODS Data was obtained from the 2008 Household National Survey. The sample comprised 27,333 individuals above 60 years who reported that they used continued-use prescription drugs. A descriptive analysis and binary and multiple multinomial logistic regressions were performed. RESULTS 86.0% of the older adults had access to all the medication they needed, and among them, 50.7% purchased said medication. Those who obtained medication from the public health system were younger (60-64 years), did not have health insurance plans, and belonged to the lower income groups. It is remarkable that 14.0% of the subjects still had no access to any continued-use medication, and for those with more than four chronic diseases, this amount reached 22.0%. Those with a greater number of chronic diseases ran a higher risk of not having access to all the medication they needed. CONCLUSIONS There are some groups of older adults with an increased risk of not obtaining all the medication they need and of purchasing it. The results of this study are expected to contribute to guide programs and plans for access to medication in Brazil. PMID:25741646

Correlates of self-injurious, aggressive and destructive behaviour in children under five who are at risk of developmental delay.

PubMed

Petty, J L; Bacarese-Hamilton, M; Davies, L E; Oliver, C

2014-01-01

Several behavioural correlates of self-injury, aggression and destructive behaviour have been identified in children and young adults with intellectual disabilities. This cross-sectional study aimed to further explore these correlates in very young children with developmental delay. Parents of 56 children (40 male) under the age of five years (mean age 2 years 10 months) completed a questionnaire about their child's behaviour and the presence of behavioural correlates, including repetitive, over-active or impulsive behaviour and more severe developmental delay. Parents reported very high prevalence of self-injurious, aggressive and destructive behaviour: 51%, 64% and 51%, respectively. A binary logistic regression revealed that a higher score on a measure of overactive and impulsive behaviour significantly predicted the presence of destructive behaviour. A multiple linear regression revealed that both repetitive behaviour and number of health problems approached significance as independent predictors of severe self-injurious behaviour. Despite the very small sample, several factors emerged as potential predictors of self-injurious, aggressive and destructive behaviour. These findings support the need for further investigation in a larger sample. Confirmation in this age group could help guide the development of targeted early intervention for these behaviours by identifying behavioural risk markers. Copyright © 2013 Elsevier Ltd. All rights reserved.

Vegetarian diets and depressive symptoms among men.

PubMed

Hibbeln, Joseph R; Northstone, Kate; Evans, Jonathan; Golding, Jean

2018-01-01

Vegetarian diets are associate with cardiovascular and other health benefits, but little is known about mental health benefits or risks. To determine whether self-identification of vegetarian dietary habits is associated with significant depressive symptoms in men. Self-report data from 9668 adult male partners of pregnant women in the Avon Longitudinal Study of Parents and Children (ALSPAC) included identification as vegetarian or vegan, dietary frequency data and the Edinburgh Post Natal Depression Scale (EPDS). Continuous and binary outcomes were assessed using multiple linear and logistic regression taking account of potential confounding variables including: age, marital status, employment status, housing tenure, number of children in the household, religion, family history of depression previous childhood psychiatric contact, cigarette and alcohol consumption. Vegetarians [n = 350 (3.6% of sample)], had higher depression scores on average than non-vegetarians (mean difference 0.96 points [95%CI + 0.53, + 1.40]) and a greater risk for EPDS scores above 10 (adjusted OR = 1.67 [95% CI: 1.14,2.44]) than non-vegetarians after adjustment for potential confounding factors. Vegetarian men have more depressive symptoms after adjustment for socio-demographic factors. Nutritional deficiencies (e.g. in cobalamin or iron) are a possible explanation for these findings, however reverse causation cannot be ruled out. Copyright © 2017. Published by Elsevier B.V.

Development and validation of a pre-hospital "Red Flag" alert for activation of intra-hospital haemorrhage control response in blunt trauma.

PubMed

Hamada, Sophie Rym; Rosa, Anne; Gauss, Tobias; Desclefs, Jean-Philippe; Raux, Mathieu; Harrois, Anatole; Follin, Arnaud; Cook, Fabrice; Boutonnet, Mathieu; Attias, Arie; Ausset, Sylvain; Boutonnet, Mathieu; Dhonneur, Gilles; Duranteau, Jacques; Langeron, Olivier; Paugam-Burtz, Catherine; Pirracchio, Romain; de St Maurice, Guillaume; Vigué, Bernard; Rouquette, Alexandra; Duranteau, Jacques

2018-05-05

Haemorrhagic shock is the leading cause of early preventable death in severe trauma. Delayed treatment is a recognized prognostic factor that can be prevented by efficient organization of care. This study aimed to develop and validate Red Flag, a binary alert identifying blunt trauma patients with high risk of severe haemorrhage (SH), to be used by the pre-hospital trauma team in order to trigger an adequate intra-hospital standardized haemorrhage control response: massive transfusion protocol and/or immediate haemostatic procedures. A multicentre retrospective study of prospectively collected data from a trauma registry (Traumabase®) was performed. SH was defined as: packed red blood cell (RBC) transfusion in the trauma room, or transfusion ≥ 4 RBC in the first 6 h, or lactate ≥ 5 mmol/L, or immediate haemostatic surgery, or interventional radiology and/or death of haemorrhagic shock. Pre-hospital characteristics were selected using a multiple logistic regression model in a derivation cohort to develop a Red Flag binary alert whose performances were confirmed in a validation cohort. Among the 3675 patients of the derivation cohort, 672 (18%) had SH. The final prediction model included five pre-hospital variables: Shock Index ≥ 1, mean arterial blood pressure ≤ 70 mmHg, point of care haemoglobin ≤ 13 g/dl, unstable pelvis and pre-hospital intubation. The Red Flag alert was triggered by the presence of any combination of at least two criteria. Its predictive performances were sensitivity 75% (72-79%), specificity 79% (77-80%) and area under the receiver operating characteristic curve 0.83 (0.81-0.84) in the derivation cohort, and were not significantly different in the independent validation cohort of 2999 patients. The Red Flag alert developed and validated in this study has high performance to accurately predict or exclude SH.

Methods for estimation of radiation risk in epidemiological studies accounting for classical and Berkson errors in doses.

PubMed

Kukush, Alexander; Shklyar, Sergiy; Masiuk, Sergii; Likhtarov, Illya; Kovgan, Lina; Carroll, Raymond J; Bouville, Andre

2011-02-16

With a binary response Y, the dose-response model under consideration is logistic in flavor with pr(Y=1 | D) = R (1+R)(-1), R = λ(0) + EAR D, where λ(0) is the baseline incidence rate and EAR is the excess absolute risk per gray. The calculated thyroid dose of a person i is expressed as Dimes=fiQi(mes)/Mi(mes). Here, Qi(mes) is the measured content of radioiodine in the thyroid gland of person i at time t(mes), Mi(mes) is the estimate of the thyroid mass, and f(i) is the normalizing multiplier. The Q(i) and M(i) are measured with multiplicative errors Vi(Q) and ViM, so that Qi(mes)=Qi(tr)Vi(Q) (this is classical measurement error model) and Mi(tr)=Mi(mes)Vi(M) (this is Berkson measurement error model). Here, Qi(tr) is the true content of radioactivity in the thyroid gland, and Mi(tr) is the true value of the thyroid mass. The error in f(i) is much smaller than the errors in ( Qi(mes), Mi(mes)) and ignored in the analysis. By means of Parametric Full Maximum Likelihood and Regression Calibration (under the assumption that the data set of true doses has lognormal distribution), Nonparametric Full Maximum Likelihood, Nonparametric Regression Calibration, and by properly tuned SIMEX method we study the influence of measurement errors in thyroid dose on the estimates of λ(0) and EAR. The simulation study is presented based on a real sample from the epidemiological studies. The doses were reconstructed in the framework of the Ukrainian-American project on the investigation of Post-Chernobyl thyroid cancers in Ukraine, and the underlying subpolulation was artificially enlarged in order to increase the statistical power. The true risk parameters were given by the values to earlier epidemiological studies, and then the binary response was simulated according to the dose-response model.

Predictive Risk Factors in the Development of Intraoperative Hyperkalemia in Adult Living Donor Liver Transplantation.

PubMed

Juang, S-E; Huang, C-E; Chen, C-L; Wang, C-H; Huang, C-J; Cheng, K-W; Wu, S-C; Shih, T-H; Yang, S-C; Wong, Z-W; Jawan, B; Lee, Y-E

2016-05-01

Hyperkalemia, defined as a serum potassium level higher than 5 mEq/L, is common in the liver transplantation setting. Severe hyperkalemia may induce fatal cardiac arrhythmias; therefore, it should be monitored and treated accordingly. The aim of the current retrospective study is to evaluate and indentify the predictive risk factors of hyperkalemia during living-donor liver transplantation (LDLT). Four hundred eighty-seven adult LDLT patients were included in the study. Intraoperative serum potassium levels were monitored at least five times during LDLT; patients with a potassium level higher than 5 mEq/L were included in group 1, and the others with normokalemia in group 2. Patients' categorical characteristics and intraoperative numeric variables with a P value <.1 were selected into a multiple binary logistic regression model. In multivariate analysis, a P value of <.05 is regarded as a risk factor in the development of hyperkalemia. Fifty-one of 487 (10.4%) patients had hyperkalemia with a serum potassium level higher than 5.0 mEq/L during LDLT. Predictive factors with P < .1 in univariate analysis (Table 1), such as anesthesia time, preoperative albumin level, Model for End-stage Liver Disease score, preoperative bilirubin level, amount of blood loss, red blood cell (RBC) and fresh frozen plasma transfused, 5% albumin administered, hemoglobin at the end of surgery, and the amount of furosemide used, were further analyzed by multivariate binary regression. Results show that the anesthesia time, preoperative serum albumin level, and RBC count are determinant risk factors in the development of the hyperkalemia in our LDLT serials. Prolonged anesthesia time, preoperative serum albumin level, and intraoperative RBC transfusion are three determinant factors in the development of intraoperative hyperkalemia, and close monitoring of serum potassium levels in patients with abovementioned risk factors are recommended. Copyright © 2016 Elsevier Inc. All rights reserved.

Combinations of Multiple Neuroimaging Markers using Logistic Regression for Auxiliary Diagnosis of Alzheimer Disease and Mild Cognitive Impairment.

PubMed

Mao, Nini; Liu, Yunting; Chen, Kewei; Yao, Li; Wu, Xia

2018-06-05

Multiple neuroimaging modalities have been developed providing various aspects of information on the human brain. Used together and properly, these complementary multimodal neuroimaging data integrate multisource information which can facilitate a diagnosis and improve the diagnostic accuracy. In this study, 3 types of brain imaging data (sMRI, FDG-PET, and florbetapir-PET) were fused in the hope to improve diagnostic accuracy, and multivariate methods (logistic regression) were applied to these trimodal neuroimaging indices. Then, the receiver-operating characteristic (ROC) method was used to analyze the outcomes of the logistic classifier, with either each index, multiples from each modality, or all indices from all 3 modalities, to investigate their differential abilities to identify the disease. With increasing numbers of indices within each modality and across modalities, the accuracy of identifying Alzheimer disease (AD) increases to varying degrees. For example, the area under the ROC curve is above 0.98 when all the indices from the 3 imaging data types are combined. Using a combination of different indices, the results confirmed the initial hypothesis that different biomarkers were potentially complementary, and thus the conjoint analysis of multiple information from multiple sources would improve the capability to identify diseases such as AD and mild cognitive impairment. © 2018 S. Karger AG, Basel.

Mathematical Magnitude.

ERIC Educational Resources Information Center

Griffin, Joseph

1978-01-01

Addition, multiplication, and exponentiation form the beginning of a natural hierarchy of binary operations on the positive integers. By employing operations above exponentiation in this hierarchy, it is possible to obtain large numbers as an immediate result of combining small familiar numbers. (Author/MP)

Multiple IMU system hardware interface design, volume 2

NASA Technical Reports Server (NTRS)

Landey, M.; Brown, D.

1975-01-01

The design of each system component is described. Emphasis is placed on functional requirements unique in this system, including data bus communication, data bus transmitters and receivers, and ternary-to-binary torquing decision logic. Mechanization drawings are presented.

The High Angular Resolution Multiplicity of Massive Stars

DTIC Science & Technology

2009-02-01

binaries: visual – stars: early-type – stars: individual ( iota Ori, delta Ori, delta Sco) – techniques: interferometric Online-only material...STATEMENT Approved for public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY

PARALLAX AND ORBITAL EFFECTS IN ASTROMETRIC MICROLENSING WITH BINARY SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nucita, A. A.; Paolis, F. De; Ingrosso, G.

2016-06-01

In gravitational microlensing, binary systems may act as lenses or sources. Identifying lens binarity is generally easy, in particular in events characterized by caustic crossing since the resulting light curve exhibits strong deviations from a smooth single-lensing light curve. In contrast, light curves with minor deviations from a Paczyński behavior do not allow one to identify the source binarity. A consequence of gravitational microlensing is the shift of the position of the multiple image centroid with respect to the source star location — the so-called astrometric microlensing signal. When the astrometric signal is considered, the presence of a binary sourcemore » manifests with a path that largely differs from that expected for single source events. Here, we investigate the astrometric signatures of binary sources taking into account their orbital motion and the parallax effect due to the Earth’s motion, which turn out not to be negligible in most cases. We also show that considering the above-mentioned effects is important in the analysis of astrometric data in order to correctly estimate the lens-event parameters.« less

Practical low-cost visual communication using binary images for deaf sign language.

PubMed

Manoranjan, M D; Robinson, J A

2000-03-01

Deaf sign language transmitted by video requires a temporal resolution of 8 to 10 frames/s for effective communication. Conventional videoconferencing applications, when operated over low bandwidth telephone lines, provide very low temporal resolution of pictures, of the order of less than a frame per second, resulting in jerky movement of objects. This paper presents a practical solution for sign language communication, offering adequate temporal resolution of images using moving binary sketches or cartoons, implemented on standard personal computer hardware with low-cost cameras and communicating over telephone lines. To extract cartoon points an efficient feature extraction algorithm adaptive to the global statistics of the image is proposed. To improve the subjective quality of the binary images, irreversible preprocessing techniques, such as isolated point removal and predictive filtering, are used. A simple, efficient and fast recursive temporal prefiltering scheme, using histograms of successive frames, reduces the additive and multiplicative noise from low-cost cameras. An efficient three-dimensional (3-D) compression scheme codes the binary sketches. Subjective tests performed on the system confirm that it can be used for sign language communication over telephone lines.

Binary encoding of multiplexed images in mixed noise.

PubMed

Lalush, David S

2008-09-01

Binary coding of multiplexed signals and images has been studied in the context of spectroscopy with models of either purely constant or purely proportional noise, and has been shown to result in improved noise performance under certain conditions. We consider the case of mixed noise in an imaging system consisting of multiple individually-controllable sources (X-ray or near-infrared, for example) shining on a single detector. We develop a mathematical model for the noise in such a system and show that the noise is dependent on the properties of the binary coding matrix and on the average number of sources used for each code. Each binary matrix has a characteristic linear relationship between the ratio of proportional-to-constant noise and the noise level in the decoded image. We introduce a criterion for noise level, which is minimized via a genetic algorithm search. The search procedure results in the discovery of matrices that outperform the Hadamard S-matrices at certain levels of mixed noise. Simulation of a seven-source radiography system demonstrates that the noise model predicts trends and rank order of performance in regions of nonuniform images and in a simple tomosynthesis reconstruction. We conclude that the model developed provides a simple framework for analysis, discovery, and optimization of binary coding patterns used in multiplexed imaging systems.

Effects of variability of X-ray binaries on the X-ray luminosity functions of Milky Way

NASA Astrophysics Data System (ADS)

Islam, Nazma; Paul, Biswajit

2016-08-01

The X-ray luminosity functions of galaxies have become a useful tool for population studies of X-ray binaries in them. The availability of long term light-curves of X-ray binaries with the All Sky X-ray Monitors opens up the possibility of constructing X-ray luminosity functions, by also including the intensity variation effects of the galactic X-ray binaries. We have constructed multiple realizations of the X-ray luminosity functions (XLFs) of Milky Way, using the long term light-curves of sources obtained in the 2-10 keV energy band with the RXTE-ASM. The observed spread seen in the value of slope of both HMXB and LMXB XLFs are due to inclusion of variable luminosities of X-ray binaries in construction of these XLFs as well as finite sample effects. XLFs constructed for galactic HMXBs in the luminosity range 1036-1039 erg/sec is described by a power-law model with a mean power-law index of -0.48 and a spread due to variability of HMXBs as 0.19. XLFs constructed for galactic LMXBs in the luminosity range 1036-1039 erg/sec has a shape of cut-off power-law with mean power-law index of -0.31 and a spread due to variability of LMXBs as 0.07.

Mesoscopic Community Structure of Financial Markets Revealed by Price and Sign Fluctuations

PubMed Central

Almog, Assaf; Besamusca, Ferry; MacMahon, Mel; Garlaschelli, Diego

2015-01-01

The mesoscopic organization of complex systems, from financial markets to the brain, is an intermediate between the microscopic dynamics of individual units (stocks or neurons, in the mentioned cases), and the macroscopic dynamics of the system as a whole. The organization is determined by “communities” of units whose dynamics, represented by time series of activity, is more strongly correlated internally than with the rest of the system. Recent studies have shown that the binary projections of various financial and neural time series exhibit nontrivial dynamical features that resemble those of the original data. This implies that a significant piece of information is encoded into the binary projection (i.e. the sign) of such increments. Here, we explore whether the binary signatures of multiple time series can replicate the same complex community organization of the financial market, as the original weighted time series. We adopt a method that has been specifically designed to detect communities from cross-correlation matrices of time series data. Our analysis shows that the simpler binary representation leads to a community structure that is almost identical with that obtained using the full weighted representation. These results confirm that binary projections of financial time series contain significant structural information. PMID:26226226

hamlet, a binary genetic switch between single- and multiple- dendrite neuron morphology.

PubMed

Moore, Adrian W; Jan, Lily Yeh; Jan, Yuh Nung

2002-08-23

The dendritic morphology of neurons determines the number and type of inputs they receive. In the Drosophila peripheral nervous system (PNS), the external sensory (ES) neurons have a single nonbranched dendrite, whereas the lineally related multidendritic (MD) neurons have extensively branched dendritic arbors. We report that hamlet is a binary genetic switch between these contrasting morphological types. In hamlet mutants, ES neurons are converted to an MD fate, whereas ectopic hamlet expression in MD precursors results in transformation of MD neurons into ES neurons. Moreover, hamlet expression induced in MD neurons undergoing dendrite outgrowth drastically reduces arbor branching.

Negative base encoding in optical linear algebra processors

NASA Technical Reports Server (NTRS)

Perlee, C.; Casasent, D.

1986-01-01

In the digital multiplication by analog convolution algorithm, the bits of two encoded numbers are convolved to form the product of the two numbers in mixed binary representation; this output can be easily converted to binary. Attention is presently given to negative base encoding, treating base -2 initially, and then showing that the negative base system can be readily extended to any radix. In general, negative base encoding in optical linear algebra processors represents a more efficient technique than either sign magnitude or 2's complement encoding, when the additions of digitally encoded products are performed in parallel.

Parallel point-multiplication architecture using combined group operations for high-speed cryptographic applications

PubMed Central

Saeedi, Ehsan; Kong, Yinan

2017-01-01

In this paper, we propose a novel parallel architecture for fast hardware implementation of elliptic curve point multiplication (ECPM), which is the key operation of an elliptic curve cryptography processor. The point multiplication over binary fields is synthesized on both FPGA and ASIC technology by designing fast elliptic curve group operations in Jacobian projective coordinates. A novel combined point doubling and point addition (PDPA) architecture is proposed for group operations to achieve high speed and low hardware requirements for ECPM. It has been implemented over the binary field which is recommended by the National Institute of Standards and Technology (NIST). The proposed ECPM supports two Koblitz and random curves for the key sizes 233 and 163 bits. For group operations, a finite-field arithmetic operation, e.g. multiplication, is designed on a polynomial basis. The delay of a 233-bit point multiplication is only 3.05 and 3.56 μs, in a Xilinx Virtex-7 FPGA, for Koblitz and random curves, respectively, and 0.81 μs in an ASIC 65-nm technology, which are the fastest hardware implementation results reported in the literature to date. In addition, a 163-bit point multiplication is also implemented in FPGA and ASIC for fair comparison which takes around 0.33 and 0.46 μs, respectively. The area-time product of the proposed point multiplication is very low compared to similar designs. The performance (1Area×Time=1AT) and Area × Time × Energy (ATE) product of the proposed design are far better than the most significant studies found in the literature. PMID:28459831

Parallel point-multiplication architecture using combined group operations for high-speed cryptographic applications.

PubMed

Hossain, Md Selim; Saeedi, Ehsan; Kong, Yinan

2017-01-01

In this paper, we propose a novel parallel architecture for fast hardware implementation of elliptic curve point multiplication (ECPM), which is the key operation of an elliptic curve cryptography processor. The point multiplication over binary fields is synthesized on both FPGA and ASIC technology by designing fast elliptic curve group operations in Jacobian projective coordinates. A novel combined point doubling and point addition (PDPA) architecture is proposed for group operations to achieve high speed and low hardware requirements for ECPM. It has been implemented over the binary field which is recommended by the National Institute of Standards and Technology (NIST). The proposed ECPM supports two Koblitz and random curves for the key sizes 233 and 163 bits. For group operations, a finite-field arithmetic operation, e.g. multiplication, is designed on a polynomial basis. The delay of a 233-bit point multiplication is only 3.05 and 3.56 μs, in a Xilinx Virtex-7 FPGA, for Koblitz and random curves, respectively, and 0.81 μs in an ASIC 65-nm technology, which are the fastest hardware implementation results reported in the literature to date. In addition, a 163-bit point multiplication is also implemented in FPGA and ASIC for fair comparison which takes around 0.33 and 0.46 μs, respectively. The area-time product of the proposed point multiplication is very low compared to similar designs. The performance ([Formula: see text]) and Area × Time × Energy (ATE) product of the proposed design are far better than the most significant studies found in the literature.

Rotational Synchronization May Enhance Habitability for Circumbinary Planets: Kepler Binary Case Studies

NASA Astrophysics Data System (ADS)

Mason, Paul A.; Zuluaga, Jorge I.; Clark, Joni M.; Cuartas-Restrepo, Pablo A.

2013-09-01

We report a mechanism capable of reducing (or increasing) stellar activity in binary stars, thereby potentially enhancing (or destroying) circumbinary habitability. In single stars, stellar aggression toward planetary atmospheres causes mass-loss, which is especially detrimental for late-type stars, because habitable zones are very close and activity is long lasting. In binaries, tidal rotational breaking reduces magnetic activity, thus reducing harmful levels of X-ray and ultraviolet (XUV) radiation and stellar mass-loss that are able to erode planetary atmospheres. We study this mechanism for all confirmed circumbinary (p-type) planets. We find that main sequence twins provide minimal flux variation and in some cases improved environments if the stars rotationally synchronize within the first Gyr. Solar-like twins, like Kepler 34 and Kepler 35, provide low habitable zone XUV fluxes and stellar wind pressures. These wide, moist, habitable zones may potentially support multiple habitable planets. Solar-type stars with lower mass companions, like Kepler 47, allow for protected planets over a wide range of secondary masses and binary periods. Kepler 38 and related binaries are marginal cases. Kepler 64 and analogs have dramatically reduced stellar aggression due to synchronization of the primary, but are limited by the short lifetime. Kepler 16 appears to be inhospitable to planets due to extreme XUV flux. These results have important implications for estimates of the number of stellar systems containing habitable planets in the Galaxy and allow for the selection of binaries suitable for follow-up searches for habitable planets.

Photometric Determination of Binary Mass Ratios in the WIYN Open Cluster Study (WOCS) Using Theoretical Isochrones

NASA Astrophysics Data System (ADS)

Cai, K.; Durisen, R. H.; Deliyannis, C. P.

2003-05-01

Binary stars in Galactic open clusters are difficult to detect without spectroscopic observations. However, from theoretical isochrones, we find that binary stars with different primary masses M1 and mass ratios q = M2/M1 have measurably different behaviors in various UBVRI color-magnitude and color-color diagrams. By using appropriate Yonsei-Yale Isochrones, in the best cases we can evaluate M1 and q to within about +/- 0.1Msun and +/- 0.1, respectively, for individual proper-motion members that have multiple WOCS UBVRI measurements of high quality. The cluster metallicity, reddening, and distance modulus and best-fit isochrones are determined self-consistently from the same WOCS data. This technique allows us to detect binaries and determine their mass ratios in open clusters without time-consuming spectrocopy, which is only sensitive to a limited range of binary separations. We will report results from this photometric technique for WOCS cluster M35 for M1 in the range of 1 to 4 Msun. For the lower main sequence, we used the empirical colors to reduce the error introduced by the problematic color transformations of Y2 Isochrones. In addition to other sources of uncertainty, we have considered effects of rapid rotation and pulsational instability. We plan to apply our method to other WOCS clusters in the future and explore differences in binary fractions and/or mass ratio distributions as a function of cluster age, metallicity, and other parameters.

Coupled binary embedding for large-scale image retrieval.

PubMed

Zheng, Liang; Wang, Shengjin; Tian, Qi

2014-08-01

Visual matching is a crucial step in image retrieval based on the bag-of-words (BoW) model. In the baseline method, two keypoints are considered as a matching pair if their SIFT descriptors are quantized to the same visual word. However, the SIFT visual word has two limitations. First, it loses most of its discriminative power during quantization. Second, SIFT only describes the local texture feature. Both drawbacks impair the discriminative power of the BoW model and lead to false positive matches. To tackle this problem, this paper proposes to embed multiple binary features at indexing level. To model correlation between features, a multi-IDF scheme is introduced, through which different binary features are coupled into the inverted file. We show that matching verification methods based on binary features, such as Hamming embedding, can be effectively incorporated in our framework. As an extension, we explore the fusion of binary color feature into image retrieval. The joint integration of the SIFT visual word and binary features greatly enhances the precision of visual matching, reducing the impact of false positive matches. Our method is evaluated through extensive experiments on four benchmark datasets (Ukbench, Holidays, DupImage, and MIR Flickr 1M). We show that our method significantly improves the baseline approach. In addition, large-scale experiments indicate that the proposed method requires acceptable memory usage and query time compared with other approaches. Further, when global color feature is integrated, our method yields competitive performance with the state-of-the-arts.

The Prevalence of Antenatal Depression and its Related Factors in Chinese Pregnant Women who Present with Obstetrical Complications.

PubMed

Zhao, Ying; Kane, Irene; Mao, Liping; Shi, Shenxun; Wang, Jing; Lin, Qiping; Luo, Jianfeng

2016-06-01

The psychological status of Chinese pregnant women who present with obstetrical complications is concerning to Chinese health professionals. This study aimed to investigate the prevalence of antenatal depression and analyzed related risk factors in a population of high-risk Chinese women. A large sample size, cross-sectional study. A total of 842 pregnant women with complications completed the Chinese version of the Postpartum Depression Screen Scale (PDSS) in this cross-sectional study. t-Test, ANOVA and Binary logistic regression tests were used in data analysis of antenatal depression and risk factors. The prevalence of major or minor depression in high-risk Chinese pregnant women during antenatal period was 8.3% and 28.9%, respectively. Independent-sample t-test and two-way analysis of variance (ANOVA) indicated significant differences in age, education, occupation and the number of complications (P<0.05). Binary logistic regression analysis indicated a significant negative association between depression and education (P<0.01) with lower educational level (OR: 0.590; 95% CI: 0.424-0.820) associated with a higher risk for depression. A significant positive association was observed between depression and age (P<0.05) with higher age (OR: 1.338; 95% CI: 1.008-1.774) correlated with a higher risk for depression. Women who experienced obstetric complications presented with higher PDSS depression scores. Screening for antenatal depression in high-risk pregnant women to promote early detection of depression and reduce health risks for universal health promotion is recommended. Copyright © 2015 Elsevier Inc. All rights reserved.

Nurses’ knowledge on phlebotomy in tertiary hospitals in China: a cross-sectional multicentric survey

PubMed Central

Cai, Qian; Zhou, Yunxian; Yang, Dangan

2017-01-01

Introduction In China, phlebotomy practice is mostly executed by nurses instead of phlebotomists. Our hypothesis was that these nurses may lack of knowledge on phlebotomy, especially factors influencing quality of blood samples. This study aims to assess the overall nurses’ knowledge on phlebotomy to provide reference for improving blood sampling practice in China. Materials and methods A survey was conducted involving nurses from 4 regions and 13 hospitals in China. A phlebotomy knowledge questionnaire was designed based on the Clinical and Laboratory Standards Institute H3-A6 guidelines, combining with the situations in China. Descriptive analysis and binary logistic regression analysis were used to analyze the knowledge level and its influencing factors. Results A total of 3400 questionnaires were distributed and 3077 valid questionnaires were returned, with an effective return rate of 90.5%. The correct rates of patient identification, hand sanitization, patient assessment, tube mixing time, needle disposing location and tube labelling were greater than 90%. However, the correct rates of order of draw (15.5%), definition of an inversion (22.5%), time to release tourniquet (18.5%) and time to change tube (28.5%) were relatively low. Binary logistic regression analysis showed that the correct rates of the aforementioned four questions were mainly related to the regional distribution of the hospitals (P < 0.001). Conclusions The knowledge level on phlebotomy among Chinese nurses was found unsatisfactory in some areas. An education program on phlebotomy should be developed for Chinese nurses to improve the consistency among different regions and to enhance nurse’s knowledge level on phlebotomy. PMID:29187796

Hopelessness and Suicidal Ideation among Patients with Depression and Neurotic Disorders Attending a Tertiary Care Centre at Eastern Nepal.

PubMed

Pokharel, R; Lama, S; Adhikari, B R

2016-09-01

Hopelessness is thought to result from a negative appraisal system and interacts with, and worsens, appraisals of defeat and trap which in turn interact with suicide schema and lead to suicidal behaviour. This study was intended to assess hopelessness and suicidal ideation among patients with depression and neurotic disorders at tertiary care centre of eastern Nepal. A cross sectional design included 70 respondents by purposive sampling technique. Beck Hopelessness Scale and Scale of Suicidal Ideation were used to measure hopelessness and suicidal ideation, respectively. Data were analyzed using SPSS statistical software. Pearson chi-square, binary logistic regression and Spearmans' rho, test were applied at 95% confidence interval. Mean ± SD age was 32.8 ± 13.5 years. Most (62.8%) of the patients were female and with the diagnosis of depression. Majority (66%) of the patients had hopelessness. There was no significant difference in hopelessness among patients with depression and neurotic disorders. About 17% respondents had suicidal ideation, among them 82.4% were female. There was no significant difference of suicidal ideation among patients with depression and neurotic disorders (p=0.013). Significant positive correlation between hopelessness and suicidal ideation was found (p=0.001). Binary logistic regression revealed hopelessness was independently related to income and family history of mental illness. Similarly, suicidal ideation was independently related to depression and family history of mental illness. Female respondents, people living under poverty and positive family history of mental illness had more hopelessness and suicidal ideation.

Quality management and job related factors predicting satisfaction of dental clinic staff in Estonia.

PubMed

Merisalu, Eda; Männik, Georg; Põlluste, Kaja

2014-01-01

The aim of the study was to explore the role of managerial style, work environment factors and burnout in determining job satisfaction during the implementation of quality improvement activities in a dental clinic. Quantitative research was carried out using a prestructured anonymous questionnaire to survey 302 respondents in Kaarli Dental Clinic, Estonia. Dental clinic staff assessed job satisfaction, managerial style, work stress and burnout levels through the implementation period of ISO 9000 quality management system in 2003 and annually during 2006-2009. Binary logistic regression was used to explain the impact of satisfaction with management and work organisation, knowledge about managerial activities, work environment and psychosocial stress and burnout on job satisfaction. The response rate limits were between 60% and 89.6%. Job satisfaction increased significantly from 2003 to 2006 and the percentage of very satisfied staff increased from 17 to 38 (p<0.01) over this period. In 2007, the proportion of very satisfied people dropped to 21% before increasing again in 2008-2009 (from 24% to 35%). Binary logistic regression analysis resulted in a model that included five groups of factors: managerial support, information about results achieved and progress to goals, work organisation and working environment, as well as factors related to career, security and planning. The average scores of emotional exhaustion showed significant decrease, correlating negatively with job satisfaction (p<0.05). The implementation of quality improvement activities in the Kaarli Dental Clinic has improved the work environment by decreasing burnout symptoms and increased job satisfaction in staff.

Injury risk functions for frontal oblique collisions.

PubMed

Andricevic, Nino; Junge, Mirko; Krampe, Jonas

2018-03-09

The objective of this article was the construction of injury risk functions (IRFs) for front row occupants in oblique frontal crashes and a comparison to IRF of nonoblique frontal crashes from the same data set. Crashes of modern vehicles from GIDAS (German In-Depth Accident Study) were used as the basis for the construction of a logistic injury risk model. Static deformation, measured via displaced voxels on the postcrash vehicles, was used to calculate the energy dissipated in the crash. This measure of accident severity was termed objective equivalent speed (oEES) because it does not depend on the accident reconstruction and thus eliminates reconstruction biases like impact direction and vehicle model year. Imputation from property damage cases was used to describe underrepresented low-severity crashes-a known shortcoming of GIDAS. Binary logistic regression was used to relate the stimuli (oEES) to the binary outcome variable (injured or not injured). IRFs for the oblique frontal impact and nonoblique frontal impact were computed for the Maximum Abbreviated Injury Scale (MAIS) 2+ and 3+ levels for adults (18-64 years). For a given stimulus, the probability of injury for a belted driver was higher in oblique crashes than in nonoblique frontal crashes. For the 25% injury risk at MAIS 2+ level, the corresponding stimulus for oblique crashes was 40 km/h but it was 64 km/h for nonoblique frontal crashes. The risk of obtaining MAIS 2+ injuries is significantly higher in oblique crashes than in nonoblique crashes. In the real world, most MAIS 2+ injuries occur in an oEES range from 30 to 60 km/h.

Mental health, employment and gender. Cross-sectional evidence in a sample of refugees from Bosnia-Herzegovina living in two Swedish regions.

PubMed

Blight, Karin Johansson; Ekblad, Solvig; Persson, Jan-Olov; Ekberg, Jan

2006-04-01

Large regional differences regarding access to employment have been observed amongst persons from Bosnia-Herzegovina coming to Sweden in 1993-1994. This has led to questions about the role of mental health. To explore this further, postal survey questionnaires were distributed to a community sample (N = 650) that was stratified and, within strata, randomly selected from a sampling frame of persons coming to Sweden from Bosnia-Herzegovina in 1993-1994. Four hundred and thirteen persons returned the questionnaire providing a response rate of 63.5%. The aim was to increase knowledge about the relationship between mental health and employment in the chosen population. The main mental health outcome measure was the Göteborg Quality of Life instrument from which 360 respondents were grouped according to low or high symptom levels. Data were cross tabulated (chi2-tested) against background variables such as age, gender and occupational status, and then tested using binary logistic regression. Binary logistic regression revealed unemployed men but not women, and women who had been working for longer periods during 1993-1999, to be associated with high levels of symptoms of poor mental health. Women living in the urban region were also overrepresented in the high symptom group. These findings indicate that, job occupancy is important to the health of men in the study. However, for the women, further understanding is needed, as job occupancy at some level as well as living in the urban region appear to be associated with poor mental health.

A predictive model for diagnosing bipolar disorder based on the clinical characteristics of major depressive episodes in Chinese population.

PubMed

Gan, Zhaoyu; Diao, Feici; Wei, Qinling; Wu, Xiaoli; Cheng, Minfeng; Guan, Nianhong; Zhang, Ming; Zhang, Jinbei

2011-11-01

A correct timely diagnosis of bipolar depression remains a big challenge for clinicians. This study aimed to develop a clinical characteristic based model to predict the diagnosis of bipolar disorder among patients with current major depressive episodes. A prospective study was carried out on 344 patients with current major depressive episodes, with 268 completing 1-year follow-up. Data were collected through structured interviews. Univariate binary logistic regression was conducted to select potential predictive variables among 19 initial variables, and then multivariate binary logistic regression was performed to analyze the combination of risk factors and build a predictive model. Receiver operating characteristic (ROC) curve was plotted. Of 19 initial variables, 13 variables were preliminarily selected, and then forward stepwise exercise produced a final model consisting of 6 variables: age at first onset, maximum duration of depressive episodes, somatalgia, hypersomnia, diurnal variation of mood, irritability. The correct prediction rate of this model was 78% (95%CI: 75%-86%) and the area under the ROC curve was 0.85 (95%CI: 0.80-0.90). The cut-off point for age at first onset was 28.5 years old, while the cut-off point for maximum duration of depressive episode was 7.5 months. The limitations of this study include small sample size, relatively short follow-up period and lack of treatment information. Our predictive models based on six clinical characteristics of major depressive episodes prove to be robust and can help differentiate bipolar depression from unipolar depression. Copyright © 2011 Elsevier B.V. All rights reserved.

Analysis of Radiation Effects in Digital Subtraction Angiography of Intracranial Artery Stenosis.

PubMed

Guo, Chaoqun; Shi, Xiaolei; Ding, Xianhui; Zhou, Zhiming

2018-04-21

Intracranial artery stenosis (IAS) is the most common cause for acute cerebral accidents. Digital subtraction angiography (DSA) is the gold standard to detect IAS and usually brings excess radiation exposure to examinees and examiners. The artery pathology might influence the interventional procedure, causing prolonged radiation effects. However, no studies on the association between IAS pathology and operational parameters are available. A retrospective analysis was conducted on 93 patients with first-ever stroke/transient ischemic attack, who received DSA examination within 3 months from onset in this single center. Comparison of baseline characteristics was determined by 2-tailed Student's t-test or the chi-square test between subjects with and without IAS. A binary logistic regression analysis was performed to determine the association between IAS pathology and the items with a P value <0.05 in Student's t-test or chi-square test. There were 93 candidates (42 with IAS and 51 without IAS) in this study. The 2 groups shared no significance of the baseline characteristics (P > 0.05). We found a significantly higher total time, higher kerma area product, greater total dose, and greater DSA dose in the IAS group than in those without IAS (P < 0.05). A binary logistic regression analysis indicated the significant association between total time and IAS pathology (P < 0.05) but no significance in kerma area product, radiation dose, and DSA dose (P > 0.05). IAS pathology would indicate a prolonged total time of DSA procedure in clinical practice. However, the radiation effects would not change with pathologic changes. Copyright © 2018 Elsevier Inc. All rights reserved.