Predicting Treatment Effect from Surrogate Endpoints and Historical Trials | Division of Cancer Prevention

Cancer.gov

By Stuart G. Baker, 2017 Introduction This software fits a zero-intercept random effects linear model to data on surrogate and true endpoints in previous trials. Requirement:  Mathematica Version 11 or later. |

Prediction of random-regression coefficient for daily milk yield after 305 days in milk by using the regression-coefficient estimates from the first 305 days.

PubMed

Yamazaki, Takeshi; Takeda, Hisato; Hagiya, Koichi; Yamaguchi, Satoshi; Sasaki, Osamu

2018-03-13

Because lactation periods in dairy cows lengthen with increasing total milk production, it is important to predict individual productivities after 305 days in milk (DIM) to determine the optimal lactation period. We therefore examined whether the random regression (RR) coefficient from 306 to 450 DIM (M2) can be predicted from those during the first 305 DIM (M1) by using a random regression model. We analyzed test-day milk records from 85690 Holstein cows in their first lactations and 131727 cows in their later (second to fifth) lactations. Data in M1 and M2 were analyzed separately by using different single-trait RR animal models. We then performed a multiple regression analysis of the RR coefficients of M2 on those of M1 during the first and later lactations. The first-order Legendre polynomials were practical covariates of random regression for the milk yields of M2. All RR coefficients for the additive genetic (AG) effect and the intercept for the permanent environmental (PE) effect of M2 had moderate to strong correlations with the intercept for the AG effect of M1. The coefficients of determination for multiple regression of the combined intercepts for the AG and PE effects of M2 on the coefficients for the AG effect of M1 were moderate to high. The daily milk yields of M2 predicted by using the RR coefficients for the AG effect of M1 were highly correlated with those obtained by using the coefficients of M2. Milk production after 305 DIM can be predicted by using the RR coefficient estimates of the AG effect during the first 305 DIM.

Isolating the cow-specific part of residual energy intake in lactating dairy cows using random regressions.

PubMed

Fischer, A; Friggens, N C; Berry, D P; Faverdin, P

2018-07-01

The ability to properly assess and accurately phenotype true differences in feed efficiency among dairy cows is key to the development of breeding programs for improving feed efficiency. The variability among individuals in feed efficiency is commonly characterised by the residual intake approach. Residual feed intake is represented by the residuals of a linear regression of intake on the corresponding quantities of the biological functions that consume (or release) energy. However, the residuals include both, model fitting and measurement errors as well as any variability in cow efficiency. The objective of this study was to isolate the individual animal variability in feed efficiency from the residual component. Two separate models were fitted, in one the standard residual energy intake (REI) was calculated as the residual of a multiple linear regression of lactation average net energy intake (NEI) on lactation average milk energy output, average metabolic BW, as well as lactation loss and gain of body condition score. In the other, a linear mixed model was used to simultaneously fit fixed linear regressions and random cow levels on the biological traits and intercept using fortnight repeated measures for the variables. This method split the predicted NEI in two parts: one quantifying the population mean intercept and coefficients, and one quantifying cow-specific deviations in the intercept and coefficients. The cow-specific part of predicted NEI was assumed to isolate true differences in feed efficiency among cows. NEI and associated energy expenditure phenotypes were available for the first 17 fortnights of lactation from 119 Holstein cows; all fed a constant energy-rich diet. Mixed models fitting cow-specific intercept and coefficients to different combinations of the aforementioned energy expenditure traits, calculated on a fortnightly basis, were compared. The variance of REI estimated with the lactation average model represented only 8% of the variance of measured NEI. Among all compared mixed models, the variance of the cow-specific part of predicted NEI represented between 53% and 59% of the variance of REI estimated from the lactation average model or between 4% and 5% of the variance of measured NEI. The remaining 41% to 47% of the variance of REI estimated with the lactation average model may therefore reflect model fitting errors or measurement errors. In conclusion, the use of a mixed model framework with cow-specific random regressions seems to be a promising method to isolate the cow-specific component of REI in dairy cows.

Application of random effects to the study of resource selection by animals

USGS Publications Warehouse

Gillies, C.S.; Hebblewhite, M.; Nielsen, S.E.; Krawchuk, M.A.; Aldridge, Cameron L.; Frair, J.L.; Saher, D.J.; Stevens, C.E.; Jerde, C.L.

2006-01-01

1. Resource selection estimated by logistic regression is used increasingly in studies to identify critical resources for animal populations and to predict species occurrence.2. Most frequently, individual animals are monitored and pooled to estimate population-level effects without regard to group or individual-level variation. Pooling assumes that both observations and their errors are independent, and resource selection is constant given individual variation in resource availability.3. Although researchers have identified ways to minimize autocorrelation, variation between individuals caused by differences in selection or available resources, including functional responses in resource selection, have not been well addressed.4. Here we review random-effects models and their application to resource selection modelling to overcome these common limitations. We present a simple case study of an analysis of resource selection by grizzly bears in the foothills of the Canadian Rocky Mountains with and without random effects.5. Both categorical and continuous variables in the grizzly bear model differed in interpretation, both in statistical significance and coefficient sign, depending on how a random effect was included. We used a simulation approach to clarify the application of random effects under three common situations for telemetry studies: (a) discrepancies in sample sizes among individuals; (b) differences among individuals in selection where availability is constant; and (c) differences in availability with and without a functional response in resource selection.6. We found that random intercepts accounted for unbalanced sample designs, and models with random intercepts and coefficients improved model fit given the variation in selection among individuals and functional responses in selection. Our empirical example and simulations demonstrate how including random effects in resource selection models can aid interpretation and address difficult assumptions limiting their generality. This approach will allow researchers to appropriately estimate marginal (population) and conditional (individual) responses, and account for complex grouping, unbalanced sample designs and autocorrelation.

Application of random effects to the study of resource selection by animals.

PubMed

Gillies, Cameron S; Hebblewhite, Mark; Nielsen, Scott E; Krawchuk, Meg A; Aldridge, Cameron L; Frair, Jacqueline L; Saher, D Joanne; Stevens, Cameron E; Jerde, Christopher L

2006-07-01

1. Resource selection estimated by logistic regression is used increasingly in studies to identify critical resources for animal populations and to predict species occurrence. 2. Most frequently, individual animals are monitored and pooled to estimate population-level effects without regard to group or individual-level variation. Pooling assumes that both observations and their errors are independent, and resource selection is constant given individual variation in resource availability. 3. Although researchers have identified ways to minimize autocorrelation, variation between individuals caused by differences in selection or available resources, including functional responses in resource selection, have not been well addressed. 4. Here we review random-effects models and their application to resource selection modelling to overcome these common limitations. We present a simple case study of an analysis of resource selection by grizzly bears in the foothills of the Canadian Rocky Mountains with and without random effects. 5. Both categorical and continuous variables in the grizzly bear model differed in interpretation, both in statistical significance and coefficient sign, depending on how a random effect was included. We used a simulation approach to clarify the application of random effects under three common situations for telemetry studies: (a) discrepancies in sample sizes among individuals; (b) differences among individuals in selection where availability is constant; and (c) differences in availability with and without a functional response in resource selection. 6. We found that random intercepts accounted for unbalanced sample designs, and models with random intercepts and coefficients improved model fit given the variation in selection among individuals and functional responses in selection. Our empirical example and simulations demonstrate how including random effects in resource selection models can aid interpretation and address difficult assumptions limiting their generality. This approach will allow researchers to appropriately estimate marginal (population) and conditional (individual) responses, and account for complex grouping, unbalanced sample designs and autocorrelation.

Risk and Protective Effects of Sibling Relationships among African American Adolescents

ERIC Educational Resources Information Center

Soli, Anna R.; McHale, Susan M.; Feinberg, Mark E.

2009-01-01

This study investigated associations between sibling relationships and adjustment among 179 African American adolescent siblings (controlling for family factors) and tested moderating effects of familism values and birth order. Two-level random intercept models revealed that familism values moderated sibling relationship-adjustment linkages,…

Further discussions on the relationship between cumulated intercepted solar radiation and crop growth

USGS Publications Warehouse

Demetriades-Shah, T.H.; Fuchs, M.; Kanemasu, E.T.; Flitcroft, I.D.

1994-01-01

A strong correlation exists between intercepted solar radiation and crop growth. We cautioned that many derivations of the functional relationship between solar energy and biomass use cumulated data, and therefore have logical and arithmetic weaknesses. We examined the growth response of plants to solar energy by using rates of change, of both interception and growth. Our analysis revealed that measurements of light interception can only establish the relationship a posteriori. Replacing interception data with normalized random numbers did not change the quality of the relations. Several scientists have contested our views. This article reconfirms the general validity of our analysis and of our conclusions, that it is not possible to determine plant growth on the sole basis of intercepted solar energy.

Model selection for logistic regression models

NASA Astrophysics Data System (ADS)

Duller, Christine

2012-09-01

Model selection for logistic regression models decides which of some given potential regressors have an effect and hence should be included in the final model. The second interesting question is whether a certain factor is heterogeneous among some subsets, i.e. whether the model should include a random intercept or not. In this paper these questions will be answered with classical as well as with Bayesian methods. The application show some results of recent research projects in medicine and business administration.

Mixed-effects models for estimating stand volume by means of small footprint airborne laser scanner data.

Treesearch

J. Breidenbach; E. Kublin; R. McGaughey; H.-E. Andersen; S. Reutebuch

2008-01-01

For this study, hierarchical data sets--in that several sample plots are located within a stand--were analyzed for study sites in the USA and Germany. The German data had an additional hierarchy as the stands are located within four distinct public forests. Fixed-effects models and mixed-effects models with a random intercept on the stand level were fit to each data...

Schema generation in recurrent neural nets for intercepting a moving target.

PubMed

Fleischer, Andreas G

2010-06-01

The grasping of a moving object requires the development of a motor strategy to anticipate the trajectory of the target and to compute an optimal course of interception. During the performance of perception-action cycles, a preprogrammed prototypical movement trajectory, a motor schema, may highly reduce the control load. Subjects were asked to hit a target that was moving along a circular path by means of a cursor. Randomized initial target positions and velocities were detected in the periphery of the eyes, resulting in a saccade toward the target. Even when the target disappeared, the eyes followed the target's anticipated course. The Gestalt of the trajectories was dependent on target velocity. The prediction capability of the motor schema was investigated by varying the visibility range of cursor and target. Motor schemata were determined to be of limited precision, and therefore visual feedback was continuously required to intercept the moving target. To intercept a target, the motor schema caused the hand to aim ahead and to adapt to the target trajectory. The control of cursor velocity determined the point of interception. From a modeling point of view, a neural network was developed that allowed the implementation of a motor schema interacting with feedback control in an iterative manner. The neural net of the Wilson type consists of an excitation-diffusion layer allowing the generation of a moving bubble. This activation bubble runs down an eye-centered motor schema and causes a planar arm model to move toward the target. A bubble provides local integration and straightening of the trajectory during repetitive moves. The schema adapts to task demands by learning and serves as forward controller. On the basis of these model considerations the principal problem of embedding motor schemata in generalized control strategies is discussed.

Multilevel Models for Intensive Longitudinal Data with Heterogeneous Autoregressive Errors: The Effect of Misspecification and Correction with Cholesky Transformation

PubMed Central

Jahng, Seungmin; Wood, Phillip K.

2017-01-01

Intensive longitudinal studies, such as ecological momentary assessment studies using electronic diaries, are gaining popularity across many areas of psychology. Multilevel models (MLMs) are most widely used analytical tools for intensive longitudinal data (ILD). Although ILD often have individually distinct patterns of serial correlation of measures over time, inferences of the fixed effects, and random components in MLMs are made under the assumption that all variance and autocovariance components are homogenous across individuals. In the present study, we introduced a multilevel model with Cholesky transformation to model ILD with individually heterogeneous covariance structure. In addition, the performance of the transformation method and the effects of misspecification of heterogeneous covariance structure were investigated through a Monte Carlo simulation. We found that, if individually heterogeneous covariances are incorrectly assumed as homogenous independent or homogenous autoregressive, MLMs produce highly biased estimates of the variance of random intercepts and the standard errors of the fixed intercept and the fixed effect of a level 2 covariate when the average autocorrelation is high. For intensive longitudinal data with individual specific residual covariance, the suggested transformation method showed lower bias in those estimates than the misspecified models when the number of repeated observations within individuals is 50 or more. PMID:28286490

Comparison of risk factors for seropositivity to feline immunodeficiency virus and feline leukemia virus among cats: a case-case study.

PubMed

Chhetri, Bimal K; Berke, Olaf; Pearl, David L; Bienzle, Dorothee

2015-02-10

Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are reported to have similar risk factors and similar recommendations apply to manage infected cats. However, some contrasting evidence exists in the literature with regard to commonly reported risk factors. In this study, we investigated whether the known risk factors for FIV and FeLV infections have a stronger effect for either infection. This retrospective study included samples from 696 cats seropositive for FIV and 593 cats seropositive for FeLV from the United States and Canada. Data were collected during two cross sectional studies, where cats were tested using IDEXX FIV/FeLV ELISA kits. To compare the effect of known risk factors for FIV infection compared to FeLV, using a case-case study design, random intercept logistic regression models were fit including cats' age, sex, neuter status, outdoor exposure, health status and type of testing facility as independent variables. A random intercept for testing facility was included to account for clustering expected in testing practices at the individual clinics and shelters. In the multivariable random intercept model, the odds of FIV compared to FeLV positive ELISA results were greater for adults (OR = 2.09, CI: 1.50-2.92), intact males (OR = 3.14, CI: 1.85-3.76), neutered males (OR = 2.68, CI: 1.44- 3.14), cats with outdoor access (OR = 2.58, CI: 1.85-3.76) and lower for cats with clinical illness (OR = 0.60, 95% CI: 0.52-0.90). The variance components obtained from the model indicated clustering at the testing facility level. Risk factors that have a greater effect on FIV seropositivity include adulthood, being male (neutered or not) and having access to outdoors, while clinical illness was a stronger predictor for FeLV seropositivity. Further studies are warranted to assess the implications of these results for the management and control of these infections.

Causal mediation analysis for longitudinal data with exogenous exposure

PubMed Central

Bind, M.-A. C.; Vanderweele, T. J.; Coull, B. A.; Schwartz, J. D.

2016-01-01

Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation. PMID:26272993

[Canopy interception characteristics of main vegetation types in Liupan Mountains of China].

PubMed

Xu, Li-hong; Shi, Zhong-jie; Wang, Yan-hui; Xiong, Wei; Yu, Peng-tao

2010-10-01

Based on field observation and modeling analysis, this paper studied the canopy interception, interception capacity, and some parameters for interception modeling of main forest types in Liupan Mountains of China. For the test main forest types, the ratio of their canopy interception to precipitation ranged from 8.59% to 17.94%, throughfall was more than 80%, and stemflow ranged from 0.23% to 3.10%. The canopy interception capacity was 0.78-1.88 mm, among which, leaf interception capacity was 0.62-1.63 mm, and stem interception capacity was 0.13-0.29 mm. Conifer forest had a higher canopy interception capacity than broad-leaved forest. The modified model considering the change of leaf area index, which was used in this paper, had a higher simulating precision than the interception model used before. The simulation results for Betula albo-sinensis forest, Pinus armandii forest, Prunus shrub, and Quercus liaotungensis-Tilia paucicostata forest were good, but those for Quercus liaotungensis forest, Pinus tabulaeformis forest, and Acer tetramerum and Euonymus sanguineus shrub were bad, which might be related to the differences in canopy structure, leaf area index, and precipitation characteristics.

A Multilevel AR(1) Model: Allowing for Inter-Individual Differences in Trait-Scores, Inertia, and Innovation Variance.

PubMed

Jongerling, Joran; Laurenceau, Jean-Philippe; Hamaker, Ellen L

2015-01-01

In this article we consider a multilevel first-order autoregressive [AR(1)] model with random intercepts, random autoregression, and random innovation variance (i.e., the level 1 residual variance). Including random innovation variance is an important extension of the multilevel AR(1) model for two reasons. First, between-person differences in innovation variance are important from a substantive point of view, in that they capture differences in sensitivity and/or exposure to unmeasured internal and external factors that influence the process. Second, using simulation methods we show that modeling the innovation variance as fixed across individuals, when it should be modeled as a random effect, leads to biased parameter estimates. Additionally, we use simulation methods to compare maximum likelihood estimation to Bayesian estimation of the multilevel AR(1) model and investigate the trade-off between the number of individuals and the number of time points. We provide an empirical illustration by applying the extended multilevel AR(1) model to daily positive affect ratings from 89 married women over the course of 42 consecutive days.

Generalized SAMPLE SIZE Determination Formulas for Investigating Contextual Effects by a Three-Level Random Intercept Model.

PubMed

Usami, Satoshi

2017-03-01

Behavioral and psychological researchers have shown strong interests in investigating contextual effects (i.e., the influences of combinations of individual- and group-level predictors on individual-level outcomes). The present research provides generalized formulas for determining the sample size needed in investigating contextual effects according to the desired level of statistical power as well as width of confidence interval. These formulas are derived within a three-level random intercept model that includes one predictor/contextual variable at each level to simultaneously cover various kinds of contextual effects that researchers can show interest. The relative influences of indices included in the formulas on the standard errors of contextual effects estimates are investigated with the aim of further simplifying sample size determination procedures. In addition, simulation studies are performed to investigate finite sample behavior of calculated statistical power, showing that estimated sample sizes based on derived formulas can be both positively and negatively biased due to complex effects of unreliability of contextual variables, multicollinearity, and violation of assumption regarding the known variances. Thus, it is advisable to compare estimated sample sizes under various specifications of indices and to evaluate its potential bias, as illustrated in the example.

Fitting rainfall interception models to forest ecosystems of Mexico

NASA Astrophysics Data System (ADS)

Návar, José

2017-05-01

Models that accurately predict forest interception are essential both for water balance studies and for assessing watershed responses to changes in land use and the long-term climate variability. This paper compares the performance of four rainfall interception models-the sparse Gash (1995), Rutter et al. (1975), Liu (1997) and two new models (NvMxa and NvMxb)-using data from four spatially extensive, structurally diverse forest ecosystems in Mexico. Ninety-eight case studies measuring interception in tropical dry (25), arid/semi-arid (29), temperate (26), and tropical montane cloud forests (18) were compiled and analyzed. Coefficients derived from raw data or published statistical relationships were used as model input to evaluate multi-storm forest interception at the case study scale. On average empirical data showed that, tropical montane cloud, temperate, arid/semi-arid and tropical dry forests intercepted 14%, 18%, 22% and 26% of total precipitation, respectively. The models performed well in predicting interception, with mean deviations between measured and modeled interception as a function of total precipitation (ME) generally <5.8% and Nash-Sutcliffe efficiency E estimators >0.66. Model fitting precision was dependent on the forest ecosystem. Arid/semi-arid forests exhibited the smallest, while tropical montane cloud forest displayed the largest ME deviations. Improved agreement between measured and modeled data requires modification of in-storm evaporation rate in the Liu; the canopy storage in the sparse Gash model; and the throughfall coefficient in the Rutter and the NvMx models. This research concludes on recommending the wide application of rainfall interception models with some caution as they provide mixed results. The extensive forest interception data source, the fitting and testing of four models, the introduction of a new model, and the availability of coefficient values for all four forest ecosystems are an important source of information and a benchmark for future investigations in this area of hydrology.

Genetic Parameter Estimates for Metabolizing Two Common Pharmaceuticals in Swine.

PubMed

Howard, Jeremy T; Ashwell, Melissa S; Baynes, Ronald E; Brooks, James D; Yeatts, James L; Maltecca, Christian

2018-01-01

In livestock, the regulation of drugs used to treat livestock has received increased attention and it is currently unknown how much of the phenotypic variation in drug metabolism is due to the genetics of an animal. Therefore, the objective of the study was to determine the amount of phenotypic variation in fenbendazole and flunixin meglumine drug metabolism due to genetics. The population consisted of crossbred female and castrated male nursery pigs ( n = 198) that were sired by boars represented by four breeds. The animals were spread across nine batches. Drugs were administered intravenously and blood collected a minimum of 10 times over a 48 h period. Genetic parameters for the parent drug and metabolite concentration within each drug were estimated based on pharmacokinetics (PK) parameters or concentrations across time utilizing a random regression model. The PK parameters were estimated using a non-compartmental analysis. The PK model included fixed effects of sex and breed of sire along with random sire and batch effects. The random regression model utilized Legendre polynomials and included a fixed population concentration curve, sex, and breed of sire effects along with a random sire deviation from the population curve and batch effect. The sire effect included the intercept for all models except for the fenbendazole metabolite (i.e., intercept and slope). The mean heritability across PK parameters for the fenbendazole and flunixin meglumine parent drug (metabolite) was 0.15 (0.18) and 0.31 (0.40), respectively. For the parent drug (metabolite), the mean heritability across time was 0.27 (0.60) and 0.14 (0.44) for fenbendazole and flunixin meglumine, respectively. The errors surrounding the heritability estimates for the random regression model were smaller compared to estimates obtained from PK parameters. Across both the PK and plasma drug concentration across model, a moderate heritability was estimated. The model that utilized the plasma drug concentration across time resulted in estimates with a smaller standard error compared to models that utilized PK parameters. The current study found a low to moderate proportion of the phenotypic variation in metabolizing fenbendazole and flunixin meglumine that was explained by genetics in the current study.

Genetic Parameter Estimates for Metabolizing Two Common Pharmaceuticals in Swine

PubMed Central

Howard, Jeremy T.; Ashwell, Melissa S.; Baynes, Ronald E.; Brooks, James D.; Yeatts, James L.; Maltecca, Christian

2018-01-01

In livestock, the regulation of drugs used to treat livestock has received increased attention and it is currently unknown how much of the phenotypic variation in drug metabolism is due to the genetics of an animal. Therefore, the objective of the study was to determine the amount of phenotypic variation in fenbendazole and flunixin meglumine drug metabolism due to genetics. The population consisted of crossbred female and castrated male nursery pigs (n = 198) that were sired by boars represented by four breeds. The animals were spread across nine batches. Drugs were administered intravenously and blood collected a minimum of 10 times over a 48 h period. Genetic parameters for the parent drug and metabolite concentration within each drug were estimated based on pharmacokinetics (PK) parameters or concentrations across time utilizing a random regression model. The PK parameters were estimated using a non-compartmental analysis. The PK model included fixed effects of sex and breed of sire along with random sire and batch effects. The random regression model utilized Legendre polynomials and included a fixed population concentration curve, sex, and breed of sire effects along with a random sire deviation from the population curve and batch effect. The sire effect included the intercept for all models except for the fenbendazole metabolite (i.e., intercept and slope). The mean heritability across PK parameters for the fenbendazole and flunixin meglumine parent drug (metabolite) was 0.15 (0.18) and 0.31 (0.40), respectively. For the parent drug (metabolite), the mean heritability across time was 0.27 (0.60) and 0.14 (0.44) for fenbendazole and flunixin meglumine, respectively. The errors surrounding the heritability estimates for the random regression model were smaller compared to estimates obtained from PK parameters. Across both the PK and plasma drug concentration across model, a moderate heritability was estimated. The model that utilized the plasma drug concentration across time resulted in estimates with a smaller standard error compared to models that utilized PK parameters. The current study found a low to moderate proportion of the phenotypic variation in metabolizing fenbendazole and flunixin meglumine that was explained by genetics in the current study. PMID:29487615

Intercepted photosynthetically active radiation in wheat canopies estimated by spectral reflectance. [Phoenix, Arizona

NASA Technical Reports Server (NTRS)

Hatfield, J. L.; Asrar, G.; Kanemasu, E. T.

1982-01-01

The interception of photosynthetically active radiation (PAR) was evaluated relative to greenness and normalized difference (MSS 7-5/7+5) for five planting dates of wheat for 1978-79 and 1979-80 in Phoenix. Intercepted PAR was calculated from a model driven by leaf area index and stage of growth. Linear relationships were found between greenness and normalized difference with a separate model representing growth and senescence of the crop. Normalized difference was a significantly better model and would be easier to apply than the empirically derived greenness parameter. For the leaf area growth portion of the season the model between PAR interception and normalized difference was the same over years, however, for the leaf senescence the models showed more variability due to the lack of data on measured interception in sparse canopies. Normalized difference could be used to estimate PAR interception directly for crop growth models.

Causal mediation analysis for longitudinal data with exogenous exposure.

PubMed

Bind, M-A C; Vanderweele, T J; Coull, B A; Schwartz, J D

2016-01-01

Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Estimating Vegetation Rainfall Interception Using Remote Sensing Observations at Very High Resolution

NASA Astrophysics Data System (ADS)

Cui, Y.; Zhao, P.; Hong, Y.; Fan, W.; Yan, B.; Xie, H.

2017-12-01

Abstract: As an important compont of evapotranspiration, vegetation rainfall interception is the proportion of gross rainfall that is intercepted, stored and subsequently evaporated from all parts of vegetation during or following rainfall. Accurately quantifying the vegetation rainfall interception at a high resolution is critical for rainfall-runoff modeling and flood forecasting, and is also essential for understanding its further impact on local, regional, and even global water cycle dynamics. In this study, the Remote Sensing-based Gash model (RS-Gash model) is developed based on a modified Gash model for interception loss estimation using remote sensing observations at the regional scale, and has been applied and validated in the upper reach of the Heihe River Basin of China for different types of vegetation. To eliminate the scale error and the effect of mixed pixels, the RS-Gash model is applied at a fine scale of 30 m with the high resolution vegetation area index retrieved by using the unified model of bidirectional reflectance distribution function (BRDF-U) for the vegetation canopy. Field validation shows that the RMSE and R2 of the interception ratio are 3.7% and 0.9, respectively, indicating the model's strong stability and reliability at fine scale. The temporal variation of vegetation rainfall interception loss and its relationship with precipitation are further investigated. In summary, the RS-Gash model has demonstrated its effectiveness and reliability in estimating vegetation rainfall interception. When compared to the coarse resolution results, the application of this model at 30-m fine resolution is necessary to resolve the scaling issues as shown in this study. Keywords: rainfall interception; remote sensing; RS-Gash analytical model; high resolution

Internal models of target motion: expected dynamics overrides measured kinematics in timing manual interceptions.

PubMed

Zago, Myrka; Bosco, Gianfranco; Maffei, Vincenzo; Iosa, Marco; Ivanenko, Yuri P; Lacquaniti, Francesco

2004-04-01

Prevailing views on how we time the interception of a moving object assume that the visual inputs are informationally sufficient to estimate the time-to-contact from the object's kinematics. Here we present evidence in favor of a different view: the brain makes the best estimate about target motion based on measured kinematics and an a priori guess about the causes of motion. According to this theory, a predictive model is used to extrapolate time-to-contact from expected dynamics (kinetics). We projected a virtual target moving vertically downward on a wide screen with different randomized laws of motion. In the first series of experiments, subjects were asked to intercept this target by punching a real ball that fell hidden behind the screen and arrived in synchrony with the visual target. Subjects systematically timed their motor responses consistent with the assumption of gravity effects on an object's mass, even when the visual target did not accelerate. With training, the gravity model was not switched off but adapted to nonaccelerating targets by shifting the time of motor activation. In the second series of experiments, there was no real ball falling behind the screen. Instead the subjects were required to intercept the visual target by clicking a mousebutton. In this case, subjects timed their responses consistent with the assumption of uniform motion in the absence of forces, even when the target actually accelerated. Overall, the results are in accord with the theory that motor responses evoked by visual kinematics are modulated by a prior of the target dynamics. The prior appears surprisingly resistant to modifications based on performance errors.

Intercepting a moving target: On-line or model-based control?

PubMed

Zhao, Huaiyong; Warren, William H

2017-05-01

When walking to intercept a moving target, people take an interception path that appears to anticipate the target's trajectory. According to the constant bearing strategy, the observer holds the bearing direction of the target constant based on current visual information, consistent with on-line control. Alternatively, the interception path might be based on an internal model of the target's motion, known as model-based control. To investigate these two accounts, participants walked to intercept a moving target in a virtual environment. We degraded the target's visibility by blurring the target to varying degrees in the midst of a trial, in order to influence its perceived speed and position. Reduced levels of visibility progressively impaired interception accuracy and precision; total occlusion impaired performance most and yielded nonadaptive heading adjustments. Thus, performance strongly depended on current visual information and deteriorated qualitatively when it was withdrawn. The results imply that locomotor interception is normally guided by current information rather than an internal model of target motion, consistent with on-line control.

Longitudinal Change of Self-Perceptions of Aging and Mortality

PubMed Central

2014-01-01

Objective. To understand the association between self-perceptions of aging (SPA) and mortality in late life. Method. The sample (n = 1,507) was drawn from the Australian Longitudinal Study of Aging (baseline age = 65–103 years). We used joint growth curve and survival models on 5 waves of data for a period of 16 years to investigate the random intercept and slope of SPA for predicting all-cause mortality. Results. The unadjusted model revealed that poor SPA at baseline, as well as decline in SPA, increased the risk of mortality (SPA intercept hazard ratio [HR] = 1.21, 95% confidence interval [CI] = 1.13, 1.31; SPA slope HR = 1.17, 95% CI = 1.02, 1.33). This relationship remained significant for the SPA intercept after adjusting for other risk factors including demographics, physical health, cognitive functioning, and well-being. Conclusion. These findings suggest that a single measurement of SPA in late life may be very informative of future long-term vulnerability to health decline and mortality. Furthermore, a dynamic measure of SPA may be indicative of adaptation to age-related changes. This supports a “self-fulfilling” hypothesis, whereby SPA is a lens through which age-related changes are interpreted, and these interpretations can affect future health and health behaviors. PMID:23419867

Simplified large African carnivore density estimators from track indices.

PubMed

Winterbach, Christiaan W; Ferreira, Sam M; Funston, Paul J; Somers, Michael J

2016-01-01

The range, population size and trend of large carnivores are important parameters to assess their status globally and to plan conservation strategies. One can use linear models to assess population size and trends of large carnivores from track-based surveys on suitable substrates. The conventional approach of a linear model with intercept may not intercept at zero, but may fit the data better than linear model through the origin. We assess whether a linear regression through the origin is more appropriate than a linear regression with intercept to model large African carnivore densities and track indices. We did simple linear regression with intercept analysis and simple linear regression through the origin and used the confidence interval for ß in the linear model y  =  αx  + ß, Standard Error of Estimate, Mean Squares Residual and Akaike Information Criteria to evaluate the models. The Lion on Clay and Low Density on Sand models with intercept were not significant ( P  > 0.05). The other four models with intercept and the six models thorough origin were all significant ( P  < 0.05). The models using linear regression with intercept all included zero in the confidence interval for ß and the null hypothesis that ß = 0 could not be rejected. All models showed that the linear model through the origin provided a better fit than the linear model with intercept, as indicated by the Standard Error of Estimate and Mean Square Residuals. Akaike Information Criteria showed that linear models through the origin were better and that none of the linear models with intercept had substantial support. Our results showed that linear regression through the origin is justified over the more typical linear regression with intercept for all models we tested. A general model can be used to estimate large carnivore densities from track densities across species and study areas. The formula observed track density = 3.26 × carnivore density can be used to estimate densities of large African carnivores using track counts on sandy substrates in areas where carnivore densities are 0.27 carnivores/100 km 2 or higher. To improve the current models, we need independent data to validate the models and data to test for non-linear relationship between track indices and true density at low densities.

Random effects coefficient of determination for mixed and meta-analysis models

PubMed Central

Demidenko, Eugene; Sargent, James; Onega, Tracy

2011-01-01

The key feature of a mixed model is the presence of random effects. We have developed a coefficient, called the random effects coefficient of determination, Rr2, that estimates the proportion of the conditional variance of the dependent variable explained by random effects. This coefficient takes values from 0 to 1 and indicates how strong the random effects are. The difference from the earlier suggested fixed effects coefficient of determination is emphasized. If Rr2 is close to 0, there is weak support for random effects in the model because the reduction of the variance of the dependent variable due to random effects is small; consequently, random effects may be ignored and the model simplifies to standard linear regression. The value of Rr2 apart from 0 indicates the evidence of the variance reduction in support of the mixed model. If random effects coefficient of determination is close to 1 the variance of random effects is very large and random effects turn into free fixed effects—the model can be estimated using the dummy variable approach. We derive explicit formulas for Rr2 in three special cases: the random intercept model, the growth curve model, and meta-analysis model. Theoretical results are illustrated with three mixed model examples: (1) travel time to the nearest cancer center for women with breast cancer in the U.S., (2) cumulative time watching alcohol related scenes in movies among young U.S. teens, as a risk factor for early drinking onset, and (3) the classic example of the meta-analysis model for combination of 13 studies on tuberculosis vaccine. PMID:23750070

Interception loss, throughfall and stemflow in a maritime pine stand. II. An application of Gash's analytical model of interception

NASA Astrophysics Data System (ADS)

Loustau, D.; Berbigier, P.; Granier, A.

1992-10-01

Interception, throughfall and stemflow were determined in an 18-year-old maritime pine stand for a period of 30 months. This involved 71 rainfall events, each corresponding either to a single storm or to several storms. Gash's analytical model of interception was used to estimate the sensitivity of interception to canopy structure and climatic parameters. The seasonal cumulative interception loss corresponded to 12.6-21.0% of the amount of rainfall, whereas throughfall and stemflow accounted for 77-83% and 1-6%, respectively. On a seasonal basis, simulated data fitted the measured data satisfactorily ( r2 = 0.75). The rainfall partitioning between interception, throughfall and stemflow was shown to be sensitive to (1) the rainfall regime, i.e. the relative importance of light storms to total rainfall, (2) the climatic parameters, rainfall rate and average evaporation rate during storms, and (3) the canopy structure parameters of the model. The low interception rate of the canopy was attributed primarily to the low leaf area index of the stand.

Randomized Clinical Trial of Interceptive and Comprehensive Orthodontics

PubMed Central

King, G.J.; Spiekerman, C.F.; Greenlee, G.M.; Huang, G.J.

2012-01-01

Focusing public insurance programs on interceptive orthodontics (IO) may increase access for low-income children. This report presents outcomes from a randomized clinical trial (RCT) comparing IO with comprehensive orthodontics (CO) in Medicaid patients. One hundred seventy pre-adolescents with Medicaid-eligible malocclusions were randomized to IO (n = 86) followed by observation (OBS) or OBS followed by CO (n = 84). One hundred thirty-four completed the trial. Models at pre-treatment (baseline) and following ≤ 2 years of intervention and 2 years of OBS (48 mos) were scored by calibrated examiners using the Peer Assessment Rating (PAR) and Index of Complexity, Outcome and Need (ICON). Overall outcomes and clinically meaningful categorical ICON data on need/acceptability, complexity, and improvement were compared. At baseline, groups were balanced by age, gender, ethnicity, and PAR/ICON scores. Most were minorities. Most (77%) were rated as difficult-to-very difficult. Scores improved significantly for both groups, but CO more than IO (PAR, 18.6 [95%CI 15.1, 22.1] vs.10.1 [95%CI 6.7, 13.4]; ICON, 44.8 [95% CI 39.7, 49.9] vs. 35.2 [95%CI 29.7, 40.6], respectively). On average, IO is effective at reducing malocclusions in Medicaid patients, but less than CO. (ClinicalTrials.gov number CT00067379) PMID:22699670

A Three-dimensional Statistical Reconstruction Model of Grapevine (Vitis vinifera) Simulating Canopy Structure Variability within and between Cultivar/Training System Pairs

PubMed Central

Louarn, Gaëtan; Lecoeur, Jérémie; Lebon, Eric

2008-01-01

Background and Aims In grapevine, canopy-structure-related variations in light interception and distribution affect productivity, yield and the quality of the harvested product. A simple statistical model for reconstructing three-dimensional (3D) canopy structures for various cultivar–training system (C × T) pairs has been implemented with special attention paid to balance the time required for model parameterization and accuracy of the representations from organ to stand scales. Such an approach particularly aims at overcoming the weak integration of interplant variability using the usual direct 3D measurement methods. Model This model is original in combining a turbid-medium-like envelope enclosing the volume occupied by vine shoots with the use of discrete geometric polygons representing leaves randomly located within this volume to represent plant structure. Reconstruction rules were adapted to capture the main determinants of grapevine shoot architecture and their variability. Using a simplified set of parameters, it was possible to describe (1) the 3D path of the main shoot, (2) the volume occupied by the foliage around this path and (3) the orientation of individual leaf surfaces. Model parameterization (estimation of the probability distribution for each parameter) was carried out for eight contrasting C × T pairs. Key Results and Conclusions The parameter values obtained in each situation were consistent with our knowledge of grapevine architecture. Quantitative assessments for the generated virtual scenes were carried out at the canopy and plant scales. Light interception efficiency and local variations of light transmittance within and between experimental plots were correctly simulated for all canopies studied. The approach predicted these key ecophysiological variables significantly more accurately than the classical complete digitization method with a limited number of plants. In addition, this model accurately reproduced the characteristics of a wide range of individual digitized plants. Simulated leaf area density and the distribution of light interception among leaves were consistent with measurements. However, at the level of individual organs, the model tended to underestimate light interception. PMID:18202006

Intercepting virtual balls approaching under different gravity conditions: evidence for spatial prediction.

PubMed

Russo, Marta; Cesqui, Benedetta; La Scaleia, Barbara; Ceccarelli, Francesca; Maselli, Antonella; Moscatelli, Alessandro; Zago, Myrka; Lacquaniti, Francesco; d'Avella, Andrea

2017-10-01

To accurately time motor responses when intercepting falling balls we rely on an internal model of gravity. However, whether and how such a model is also used to estimate the spatial location of interception is still an open question. Here we addressed this issue by asking 25 participants to intercept balls projected from a fixed location 6 m in front of them and approaching along trajectories with different arrival locations, flight durations, and gravity accelerations (0 g and 1 g ). The trajectories were displayed in an immersive virtual reality system with a wide field of view. Participants intercepted approaching balls with a racket, and they were free to choose the time and place of interception. We found that participants often achieved a better performance with 1 g than 0 g balls. Moreover, the interception points were distributed along the direction of a 1 g path for both 1 g and 0 g balls. In the latter case, interceptions tended to cluster on the upper half of the racket, indicating that participants aimed at a lower position than the actual 0 g path. These results suggest that an internal model of gravity was probably used in predicting the interception locations. However, we found that the difference in performance between 1 g and 0 g balls was modulated by flight duration, the difference being larger for faster balls. In addition, the number of peaks in the hand speed profiles increased with flight duration, suggesting that visual information was used to adjust the motor response, correcting the prediction to some extent. NEW & NOTEWORTHY Here we show that an internal model of gravity plays a key role in predicting where to intercept a fast-moving target. Participants also assumed an accelerated motion when intercepting balls approaching in a virtual environment at constant velocity. We also show that the role of visual information in guiding interceptive movement increases when more time is available. Copyright © 2017 the American Physiological Society.

Modelling rainfall interception by a lowland tropical rain forest in northeastern Puerto Rico

NASA Astrophysics Data System (ADS)

Schellekens, J.; Scatena, F. N.; Bruijnzeel, L. A.; Wickel, A. J.

1999-12-01

Recent surveys of tropical forest water use suggest that rainfall interception by the canopy is largest in wet maritime locations. To investigate the underlying processes at one such location—the Luquillo Experimental Forest in eastern Puerto Rico—66 days of detailed throughfall and above-canopy climatic data were collected in 1996 and analysed using the Rutter and Gash models of rainfall interception. Throughfall occurred on 80% of the days distributed over 80 rainfall events. Measured interception loss was 50% of gross precipitation. When Penman-Monteith based estimates for the wet canopy evaporation rate (0.11 mm h -1 on average) and a canopy storage of 1.15 mm were used, both models severely underestimated measured interception loss. A detailed analysis of four storms using the Rutter model showed that optimizing the model for the wet canopy evaporation component yielded much better results than increasing the canopy storage capacity. However, the Rutter model failed to properly estimate throughfall amounts during an exceptionally large event. The analytical model, on the other hand, was capable of representing interception during the extreme event, but once again optimizing wet canopy evaporation rates produced a much better fit than optimizing the canopy storage capacity. As such, the present results support the idea that it is primarily a high rate of evaporation from a wet canopy that is responsible for the observed high interception losses.

Low Probability of Intercept Waveforms via Intersymbol Dither Performance Under Multiple Conditions

DTIC Science & Technology

2009-03-01

United States Air Force, Department of Defense, or the United States Government . AFIT/GE/ENG/09-23 Low Probability of Intercept Waveforms via...21 D random variable governing the distribution of dither values 21 p (ct) D (t) probability density function of the...potential performance loss of a non-cooperative receiver compared to a cooperative receiver designed to account for ISI and multipath. 1.3 Thesis

Low Probability of Intercept Waveforms via Intersymbol Dither Performance Under Multipath Conditions

DTIC Science & Technology

2009-03-01

United States Air Force, Department of Defense, or the United States Government . AFIT/GE/ENG/09-23 Low Probability of Intercept Waveforms via...21 D random variable governing the distribution of dither values 21 p (ct) D (t) probability density function of the...potential performance loss of a non-cooperative receiver compared to a cooperative receiver designed to account for ISI and multipath. 1.3 Thesis

Random effects coefficient of determination for mixed and meta-analysis models.

PubMed

Demidenko, Eugene; Sargent, James; Onega, Tracy

2012-01-01

The key feature of a mixed model is the presence of random effects. We have developed a coefficient, called the random effects coefficient of determination, [Formula: see text], that estimates the proportion of the conditional variance of the dependent variable explained by random effects. This coefficient takes values from 0 to 1 and indicates how strong the random effects are. The difference from the earlier suggested fixed effects coefficient of determination is emphasized. If [Formula: see text] is close to 0, there is weak support for random effects in the model because the reduction of the variance of the dependent variable due to random effects is small; consequently, random effects may be ignored and the model simplifies to standard linear regression. The value of [Formula: see text] apart from 0 indicates the evidence of the variance reduction in support of the mixed model. If random effects coefficient of determination is close to 1 the variance of random effects is very large and random effects turn into free fixed effects-the model can be estimated using the dummy variable approach. We derive explicit formulas for [Formula: see text] in three special cases: the random intercept model, the growth curve model, and meta-analysis model. Theoretical results are illustrated with three mixed model examples: (1) travel time to the nearest cancer center for women with breast cancer in the U.S., (2) cumulative time watching alcohol related scenes in movies among young U.S. teens, as a risk factor for early drinking onset, and (3) the classic example of the meta-analysis model for combination of 13 studies on tuberculosis vaccine.

[Canopy interception of sub-alpine dark coniferous communities in western Sichuan, China].

PubMed

Lü, Yu-liang; Liu, Shi-rong; Sun, Peng-sen; Liu, Xing-liang; Zhang, Rui-pu

2007-11-01

Based on field measurements of throughfall and stemflow in combination with climatic data collected from the meteorological station adjacent to the studied sub-alpine dark coniferous forest in Wolong, Sichuan Province, canopy interception of sub-alpine dark coniferous forests was analyzed and modeled at both stand scale and catchment scale. The results showed that monthly interception rate of Fargesia nitida, Bashania fangiana--Abies faxoniana old-growth ranged from 33% Grass to 72%, with the average of 48%. In growing season, there was a linear or powerful or exponential relationship between rainfall and interception an. a negative exponential relationship between rainfall and interception rate. The mean maximum canopy interception by the vegetation in the catchment of in.44 km was 1.74 ment and the significant differences among the five communities occurred in the following sequence: Moss-Fargesia nitida, Bashan afanglana-A. faxoniana stand > Grass-F. nitida, B. fangiana-A. faxoniana stand > Moss-Rhododendron spp.-A. faxoniana stand > Grass-Rh. spp.-A. faxoniana stand > Rh. spp. shrub. In addition, a close linear relationship existed between leaf area index (LAI) and maximum canopy interception. The simulated value of canopy interception rate, maximum canopy interception rate and addition interception rate of the vegetation in the catchment were 39%, 25% and 14%, respectively. Simulation of the canopy interception model was better at the overall growing season scale, that the mean relative error was 9%-14%.

On interception modelling of a lowland coastal rainforest in northern Queensland, Australia

NASA Astrophysics Data System (ADS)

Wallace, Jim; McJannet, Dave

2006-10-01

SummaryRecent studies of the water balance of tropical rainforests in northern Queensland have revealed that large fractions of rainfall, up to 30%, are intercepted by the canopy and lost as evaporation. These loss rates are much higher than those reported for continental rainforests, for example, in the Amazon basin, where interception is around 9% of rainfall. Higher interception losses have been found in coastal and mountain rainforests and substantial advection of energy during rainfall is proposed to account for these results. This paper uses a process based model of interception to analyse the interception losses at Oliver Creek, a lowland coastal rainforest site in northern Queensland with a mean annual rainfall of 3952 mm. The observed interception loss of 25% of rainfall for the period August 2001 to January 2004 can be reproduced by the model with a suitable choice of the three key controlling variables, the canopy storage capacity, mean rainfall rate and mean wet canopy evaporation rate. Our analyses suggest that the canopy storage capacity of the Oliver Creek rainforest is between 3.0 and 3.5 mm, higher than reported for most other rainforests. Despite the high canopy capacity at our site, the interception losses can only be accounted for with energy advection during rainfall in the range 40-70% of the incident energy.

Measuring and modelling interception loss by an isolated olive tree in a traditional olive grove - pasture system

NASA Astrophysics Data System (ADS)

Nóbrega, Cristina; Pereira, Fernando L.; Valente, Fernanda

2015-04-01

Water losses associated to the rainfall interception process by trees can be an important component of the local hydrologic balance and must be accounted for when implementing any sustainable water management programme. In many dry areas of the Mediterranean region where agro-forestry systems are common, those programmes are crucial to foster adequate water conservation measures. Recent studies have shown that the evaluation of interception loss in sparse forests or tree plantations should be made for individual trees, being the total value determined as the sum of the individual contributions. Following this approach, rainfall interception was measured and modelled over two years, in an isolated Olea europeaea L. tree, in a traditional low-density olive grove in Castelo Branco, central Portugal. Total interception loss over the experimental period was 243.5 mm, on a tree crown projected area basis, corresponding to 18.0% of gross rainfall (Pg). Modelling made for each rainfall event using the sparse version of the Gash model, slightly underestimated interception loss with a value of 240.5 mm, i.e., 17.8 % ofPg. Modelling quality, evaluated according to a number of criteria, was good, allowing the conclusion that the methodology used was adequate. Modelling was also made on a daily basis, i.e., assuming a single storm per rainday. In this case, interception loss was overestimated by 12%, mostly because 72% of all rainfall events lasted for more than a day.

Exploring the spatial distribution of light interception and photosynthesis of canopies by means of a functional-structural plant model.

PubMed

Sarlikioti, V; de Visser, P H B; Marcelis, L F M

2011-04-01

At present most process-based models and the majority of three-dimensional models include simplifications of plant architecture that can compromise the accuracy of light interception simulations and, accordingly, canopy photosynthesis. The aim of this paper is to analyse canopy heterogeneity of an explicitly described tomato canopy in relation to temporal dynamics of horizontal and vertical light distribution and photosynthesis under direct- and diffuse-light conditions. Detailed measurements of canopy architecture, light interception and leaf photosynthesis were carried out on a tomato crop. These data were used for the development and calibration of a functional-structural tomato model. The model consisted of an architectural static virtual plant coupled with a nested radiosity model for light calculations and a leaf photosynthesis module. Different scenarios of horizontal and vertical distribution of light interception, incident light and photosynthesis were investigated under diffuse and direct light conditions. Simulated light interception showed a good correspondence to the measured values. Explicitly described leaf angles resulted in higher light interception in the middle of the plant canopy compared with fixed and ellipsoidal leaf-angle distribution models, although the total light interception remained the same. The fraction of light intercepted at a north-south orientation of rows differed from east-west orientation by 10 % on winter and 23 % on summer days. The horizontal distribution of photosynthesis differed significantly between the top, middle and lower canopy layer. Taking into account the vertical variation of leaf photosynthetic parameters in the canopy, led to approx. 8 % increase on simulated canopy photosynthesis. Leaf angles of heterogeneous canopies should be explicitly described as they have a big impact both on light distribution and photosynthesis. Especially, the vertical variation of photosynthesis in canopy is such that the experimental approach of photosynthesis measurements for model parameterization should be revised.

Exploring the spatial distribution of light interception and photosynthesis of canopies by means of a functional–structural plant model

PubMed Central

Sarlikioti, V.; de Visser, P. H. B.; Marcelis, L. F. M.

2011-01-01

Background and Aims At present most process-based models and the majority of three-dimensional models include simplifications of plant architecture that can compromise the accuracy of light interception simulations and, accordingly, canopy photosynthesis. The aim of this paper is to analyse canopy heterogeneity of an explicitly described tomato canopy in relation to temporal dynamics of horizontal and vertical light distribution and photosynthesis under direct- and diffuse-light conditions. Methods Detailed measurements of canopy architecture, light interception and leaf photosynthesis were carried out on a tomato crop. These data were used for the development and calibration of a functional–structural tomato model. The model consisted of an architectural static virtual plant coupled with a nested radiosity model for light calculations and a leaf photosynthesis module. Different scenarios of horizontal and vertical distribution of light interception, incident light and photosynthesis were investigated under diffuse and direct light conditions. Key Results Simulated light interception showed a good correspondence to the measured values. Explicitly described leaf angles resulted in higher light interception in the middle of the plant canopy compared with fixed and ellipsoidal leaf-angle distribution models, although the total light interception remained the same. The fraction of light intercepted at a north–south orientation of rows differed from east–west orientation by 10 % on winter and 23 % on summer days. The horizontal distribution of photosynthesis differed significantly between the top, middle and lower canopy layer. Taking into account the vertical variation of leaf photosynthetic parameters in the canopy, led to approx. 8 % increase on simulated canopy photosynthesis. Conclusions Leaf angles of heterogeneous canopies should be explicitly described as they have a big impact both on light distribution and photosynthesis. Especially, the vertical variation of photosynthesis in canopy is such that the experimental approach of photosynthesis measurements for model parameterization should be revised. PMID:21355008

Automated Neuropsychological Assessment Metrics Version 4 (ANAM4): Select Psychometric Properties and Administration Procedures

DTIC Science & Technology

2012-12-01

month no- cost extension for this study was approved on 7 November 2012, extending study activities through December 2013. A modified statement of work...approved as part of the no- cost extension and currently pending approval by the USARIEM HURC (Amendment #14), is presented in Table 2. 5...ptjournal.apta.org/Downloaded from 13     time. SAS 9.2 was used to perform a mixed model analysis with random individual intercept to account for

Visual Attention to Radar Displays

NASA Technical Reports Server (NTRS)

Moray, N.; Richards, M.; Brophy, C.

1984-01-01

A model is described which predicts the allocation of attention to the features of a radar display. It uses the growth of uncertainty and the probability of near collision to call the eye to a feature of the display. The main source of uncertainty is forgetting following a fixation, which is modelled as a two dimensional diffusion process. The model was used to predict information overload in intercept controllers, and preliminary validation obtained by recording eye movements of intercept controllers in simulated and live (practice) interception.

Global canopy interception from satellite observations

USDA-ARS?s Scientific Manuscript database

A new methodology for retrieving rainfall interception rates from multi satellite observations is presented. The approach makes use of the daily productof the Global Precipitation Climatology Project (GPCP) as driving data and applies Gash’s analytical model to derive interception rates at global sc...

Internal models and prediction of visual gravitational motion.

PubMed

Zago, Myrka; McIntyre, Joseph; Senot, Patrice; Lacquaniti, Francesco

2008-06-01

Baurès et al. [Baurès, R., Benguigui, N., Amorim, M.-A., & Siegler, I. A. (2007). Intercepting free falling objects: Better use Occam's razor than internalize Newton's law. Vision Research, 47, 2982-2991] rejected the hypothesis that free-falling objects are intercepted using a predictive model of gravity. They argued instead for "a continuous guide for action timing" based on visual information updated till target capture. Here we show that their arguments are flawed, because they fail to consider the impact of sensori-motor delays on interception behaviour and the need for neural compensation of such delays. When intercepting a free-falling object, the delays can be overcome by a predictive model of the effects of gravity on target motion.

Computer-aided mathematical analysis of probability of intercept for ground-based communication intercept system

NASA Astrophysics Data System (ADS)

Park, Sang Chul

1989-09-01

We develop a mathematical analysis model to calculate the probability of intercept (POI) for the ground-based communication intercept (COMINT) system. The POI is a measure of the effectiveness of the intercept system. We define the POI as the product of the probability of detection and the probability of coincidence. The probability of detection is a measure of the receiver's capability to detect a signal in the presence of noise. The probability of coincidence is the probability that an intercept system is available, actively listening in the proper frequency band, in the right direction and at the same time that the signal is received. We investigate the behavior of the POI with respect to the observation time, the separation distance, antenna elevations, the frequency of the signal, and the receiver bandwidths. We observe that the coincidence characteristic between the receiver scanning parameters and the signal parameters is the key factor to determine the time to obtain a given POI. This model can be used to find the optimal parameter combination to maximize the POI in a given scenario. We expand this model to a multiple system. This analysis is conducted on a personal computer to provide the portability. The model is also flexible and can be easily implemented under different situations.

Study on Light Interception and Biomass Production of Different Cotton Cultivars

PubMed Central

Mao, Shuchun; Han, Yingchun; Feng, Lu; Wang, Guoping; Yang, Beifang; Zhi, Xiaoyu; Fan, Zhengyi; Lei, Yaping; Du, Wenli; Li, Yabing

2016-01-01

Identifying the characteristics of light interception and utilization is of great significance for improving the potential photosynthetic activity of plants. The present research investigates the differences in absorbing and converting photosynthetically active radiation (PAR) among various cotton cultivars. Field experiments were conducted in 2012, 2013 and 2014 in Anyang, Henan, China. Ten cultivars with different maturity and plant architectures were planted at a density of 60,000 plants ha-1 in randomized blocks, with three replicates. The spatial distribution of light in canopy was measured and quantified with a geo-statistical method, according to which the cumulative amount of intercepted radiation was calculated by Simpson 3/8 rules. Finally, light interception was analyzed in association with the biomass accumulation of different cultivars. The key results were: (1) late-maturing varieties with an incompact plant architecture captured more solar radiation throughout the whole growth period than middle varieties with columnar architecture and even more than early varieties with compact architecture, and they produced more biomass; (2) the highest PAR interception ratio and the maximum biomass accumulation rate occurred during the blossoming and boll-forming stage, when leaf area index (LAI) reached its peak; (3) the distribution within the canopy presented a significant spatial heterogeneity, and at late growing stage, the PAR was mainly intercepted by upper canopies in incompact-type plant communities, but was more homogeneous in columnar-type plants; however, the majority of radiation was transmitted through the canopy in compact-type colonies; (4) there was not a consistent variation relationship between the cumulative intercepted PAR (iPAR) and biomass among these cultivars over the three years of the study. Based on these results, we attempted to clarify the distinction in light spatial distribution within different canopies and the patterns of PAR interception in diverse cotton cultivars with different hereditary characters, thereby providing a significant basis for researchers to select cultivars with appropriate growth period and optimal plant architecture for improvement of light interception and utilization. PMID:27227675

Accounting for intracell flow in models with emphasis on water table recharge and stream-aquifer interaction: 1. Problems and concepts

USGS Publications Warehouse

Jorgensen, Donald G.; Signor, Donald C.; Imes, Jeffrey L.

1989-01-01

Intracell flow is important in modeling cells that contain both sources and sinks. Special attention is needed if recharge through the water table is a source. One method of modeling multiple sources and sinks is to determine the net recharge per cell. For example, for a model cell containing both a sink and recharge through the water table, the amount of recharge should be reduced by the ratio of the area of influence of the sink within the cell to the area of the cell. The reduction is the intercepted portion of the recharge. In a multilayer model this amount is further reduced by a proportion factor, which is a function of the depth of the flow lines from the water table boundary to the internal sink. A gaining section of a stream is a typical sink. The aquifer contribution to a gaining stream can be conceptualized as having two parts; the first part is the intercepted lateral flow from the water table and the second is the flow across the streambed due to differences in head between the water level in the stream and the aquifer below. The amount intercepted is a function of the geometry of the cell, but the amount due to difference in head across the stream bed is largely independent of cell geometry. A discharging well can intercept recharge through the water table within a model cell. The net recharge to the cell would be reduced in proportion to the area of influence of the well within the cell. The area of influence generally changes with time. Thus the amount of intercepted recharge and net recharge may not be constant with time. During periods when the well is not discharging there will be no intercepted recharge even though the area of influence from previous pumping may still exist. The reduction of net recharge per cell due to internal interception of flow will result in a model-calculated mass balance less than the prototype. Additionally the “effective transmissivity” along the intercell flow paths may be altered when flow paths are occupied by intercepted recharge.

Associations between Stress Biology Indicators and Overweight across Toddlerhood

PubMed Central

Miller, Alison L.; Kaciroti, Niko; Sturza, Julie; Retzloff, Lauren; Rosenblum, Katherine; Vazquez, Delia M.; Lumeng, Julie C.

2017-01-01

Biological stress responses are proposed as a pathway through which stress exposure can “get under the skin” and lead to health problems, specifically obesity. Yet, it is not clear when such associations may emerge or whether they are bidirectional. Cortisol and salivary alpha amylase (sAA) were considered indicators of the biological stress response. We tested the longitudinal association between cortisol and sAA and weight in 215 low-income children at ages 21, 27, and 33 months (52% male; 46% non-Hispanic white). sAA and cortisol intercept and slope (representing morning level and rate of change across the day) were calculated for each age point using random effect models. Children were weighed and length measured and categorized as overweight versus normal weight (overweight defined as weight-for-length z-score ≥ 85th percentile for age and sex). Cross-lagged models stratified by sex and controlling for birthweight z-score tested the concurrent and cross-lagged associations between each of 4 indices of stress biology individually (cortisol and sAA intercept and slope) and overweight. Overweight status was correlated across time. Cortisol and sAA were correlated across occasions of measurement, though somewhat less strongly in boys. There were no concurrent associations between stress indicators and overweight. sAA at 27 months predicted greater risk of overweight at 33 months in girls, such that both lower sAA intercept and more rapidly increasing sAA at 27 months predicted greater risk of overweight at 33 months (β=−0.64, p<.05 and β=1.09, p<.05, respectively). For boys only, overweight at 21 months predicted lower sAA intercept at 27 months (β=−0.35, p<.05). Findings suggest that longitudinal associations of stress biology and weight status may be present only on a limited basis very early in the lifespan. PMID:28273588

Development and testing of a snow interceptometer to quantify canopy water storage and interception processes in the rain/snow transition zone of the North Cascades, Washington, USA

NASA Astrophysics Data System (ADS)

Martin, Kael A.; Van Stan, John T.; Dickerson-Lange, Susan E.; Lutz, James A.; Berman, Jeffrey W.; Gersonde, Rolf; Lundquist, Jessica D.

2013-06-01

Tree canopy snow interception is a significant hydrological process, capable of removing up to 60% of snow from the ground snowpack. Our understanding of canopy interception has been limited by our ability to measure whole canopy water storage in an undisturbed forest setting. This study presents a relatively inexpensive technique for directly measuring snow canopy water storage using an interceptometer, adapted from Friesen et al. (2008). The interceptometer is composed of four linear motion position sensors distributed evenly around the tree trunk. We incorporate a trunk laser-mapping installation method for precise sensor placement to reduce signal error due to sensor misalignment. Through calibration techniques, the amount of canopy snow required to produce the measured displacements can be calculated. We demonstrate instrument performance on a western hemlock (Tsuga heterophylla) for a snow interception event in November 2011. We find a snow capture efficiency of 83 ± 15% of accumulated ground snowfall with a maximum storage capacity of 50 ± 8 mm snow water equivalent (SWE). The observed interception event is compared to simulated interception, represented by the variable infiltration capacity (VIC) hydrologic model. The model generally underreported interception magnitude by 33% using a leaf area index (LAI) of 5 and 16% using an LAI of 10. The interceptometer captured intrastorm accumulation and melt rates up to 3 and 0.75 mm SWE h-1, respectively, which the model failed to represent. While further implementation and validation is necessary, our preliminary results indicate that forest interception magnitude may be underestimated in maritime areas.

Dual-polarized feed antenna apparatus and method of use

NASA Technical Reports Server (NTRS)

Sarehraz, Mohammed (Inventor); Buckle, Kenneth A. (Inventor); Stefanakos, Elias (Inventor); Weller, Thomas (Inventor); Goswami, D. Yogi (Inventor)

2009-01-01

An antenna apparatus and method for the interception of randomly polarized electromagnetic waves utilizing a dual polarized antenna which is excited through a cross-slot aperture using two well-isolated orthogonal feeds.

Dual-polarized feed antenna apparatus and method of use

NASA Technical Reports Server (NTRS)

Sarehraz, Mohammad (Inventor); Buckle, Kenneth A. (Inventor); Stefanakos, Elias (Inventor); Weller, Thomas (Inventor); Goswami, D. Yogi (Inventor)

2008-01-01

An antenna apparatus and method for the interception of randomly polarized electromagnetic waves utilizing a dual polarized antenna which is excited through a cross-slot aperture using two well-isolated orthogonal feeds.

Visuo-motor coordination and internal models for object interception.

PubMed

Zago, Myrka; McIntyre, Joseph; Senot, Patrice; Lacquaniti, Francesco

2009-02-01

Intercepting and avoiding collisions with moving objects are fundamental skills in daily life. Anticipatory behavior is required because of significant delays in transforming sensory information about target and body motion into a timed motor response. The ability to predict the kinematics and kinetics of interception or avoidance hundreds of milliseconds before the event may depend on several different sources of information and on different strategies of sensory-motor coordination. What are exactly the sources of spatio-temporal information and what are the control strategies remain controversial issues. Indeed, these topics have been the battlefield of contrasting views on how the brain interprets visual information to guide movement. Here we attempt a synthetic overview of the vast literature on interception. We discuss in detail the behavioral and neurophysiological aspects of interception of targets falling under gravity, as this topic has received special attention in recent years. We show that visual cues alone are insufficient to predict the time and place of interception or avoidance, and they need to be supplemented by prior knowledge (or internal models) about several features of the dynamic interaction with the moving object.

Binomial outcomes in dataset with some clusters of size two: can the dependence of twins be accounted for? A simulation study comparing the reliability of statistical methods based on a dataset of preterm infants.

PubMed

Sauzet, Odile; Peacock, Janet L

2017-07-20

The analysis of perinatal outcomes often involves datasets with some multiple births. These are datasets mostly formed of independent observations and a limited number of clusters of size two (twins) and maybe of size three or more. This non-independence needs to be accounted for in the statistical analysis. Using simulated data based on a dataset of preterm infants we have previously investigated the performance of several approaches to the analysis of continuous outcomes in the presence of some clusters of size two. Mixed models have been developed for binomial outcomes but very little is known about their reliability when only a limited number of small clusters are present. Using simulated data based on a dataset of preterm infants we investigated the performance of several approaches to the analysis of binomial outcomes in the presence of some clusters of size two. Logistic models, several methods of estimation for the logistic random intercept models and generalised estimating equations were compared. The presence of even a small percentage of twins means that a logistic regression model will underestimate all parameters but a logistic random intercept model fails to estimate the correlation between siblings if the percentage of twins is too small and will provide similar estimates to logistic regression. The method which seems to provide the best balance between estimation of the standard error and the parameter for any percentage of twins is the generalised estimating equations. This study has shown that the number of covariates or the level two variance do not necessarily affect the performance of the various methods used to analyse datasets containing twins but when the percentage of small clusters is too small, mixed models cannot capture the dependence between siblings.

WATERSHED SCALE RAINFALL INTERCEPTION ON TWO FORESTED WATERSHEDS IN THE LUQUILLO MOUNTAINS OF PUERTO RICO

Treesearch

F.N. SCATENA

1990-01-01

Interception losses were monitored for one year and related to vegetation characteristics in two forested watersheds in the Luquillo Experimental Forest of Puerto Rico. Total watershed interception was then modeled by weighting values of throughfall measured in representative areas of different vegetation types by the total watershed area of that vegetation group....

First-Grade Cognitive Abilities as Long-Term Predictors of Reading Comprehension and Disability Status

PubMed Central

Fuchs, Douglas; Compton, Donald L.; Fuchs, Lynn S.; Bryant, V. Joan; Hamlett, Carol L.; Lambert, Warren

2012-01-01

In a sample of 195 first graders selected for poor reading performance, the authors explored four cognitive predictors of later reading comprehension and reading disability (RD) status. In fall of first grade, the authors measured the children’s phonological processing, rapid automatized naming (RAN), oral language comprehension, and nonverbal reasoning. Throughout first grade, they also modeled the students’ reading progress by means of weekly Word Identification Fluency (WIF) tests to derive December and May intercepts. The authors assessed their reading comprehension in the spring of Grades 1–5. With the four cognitive variables and the WIF December intercept as predictors, 50.3% of the variance in fifth-grade reading comprehension was explained: 52.1% of this 50.3% was unique to the cognitive variables, 13.1% to the WIF December intercept, and 34.8% was shared. All five predictors were statistically significant. The same four cognitive variables with the May (rather than December) WIF intercept produced a model that explained 62.1% of the variance. Of this amount, the cognitive variables and May WIF intercept accounted for 34.5% and 27.7%, respectively; they shared 37.8%. All predictors in this model were statistically significant except RAN. Logistic regression analyses indicated that the accuracy with which the cognitive variables predicted end-of-fifth-grade RD status was 73.9%. The May WIF intercept contributed reliably to this prediction; the December WIF intercept did not. Results are discussed in terms of a role for cognitive abilities in identifying, classifying, and instructing students with severe reading problems. PMID:22539057

First-grade cognitive abilities as long-term predictors of reading comprehension and disability status.

PubMed

Fuchs, Douglas; Compton, Donald L; Fuchs, Lynn S; Bryant, V Joan; Hamlett, Carol L; Lambert, Warren

2012-01-01

In a sample of 195 first graders selected for poor reading performance, the authors explored four cognitive predictors of later reading comprehension and reading disability (RD) status. In fall of first grade, the authors measured the children's phonological processing, rapid automatized naming (RAN), oral language comprehension, and nonverbal reasoning. Throughout first grade, they also modeled the students' reading progress by means of weekly Word Identification Fluency (WIF) tests to derive December and May intercepts. The authors assessed their reading comprehension in the spring of Grades 1-5. With the four cognitive variables and the WIF December intercept as predictors, 50.3% of the variance in fifth-grade reading comprehension was explained: 52.1% of this 50.3% was unique to the cognitive variables, 13.1% to the WIF December intercept, and 34.8% was shared. All five predictors were statistically significant. The same four cognitive variables with the May (rather than December) WIF intercept produced a model that explained 62.1% of the variance. Of this amount, the cognitive variables and May WIF intercept accounted for 34.5% and 27.7%, respectively; they shared 37.8%. All predictors in this model were statistically significant except RAN. Logistic regression analyses indicated that the accuracy with which the cognitive variables predicted end-of-fifth-grade RD status was 73.9%. The May WIF intercept contributed reliably to this prediction; the December WIF intercept did not. Results are discussed in terms of a role for cognitive abilities in identifying, classifying, and instructing students with severe reading problems.

The narrow-leaf syndrome: a functional and evolutionary approach to the form of fog-harvesting rosette plants.

PubMed

Martorell, Carlos; Ezcurra, Exequiel

2007-04-01

Plants that use fog as an important water-source frequently have a rosette growth habit. The performance of this morphology in relation to fog interception has not been studied. Some first-principles from physics predict that narrow leaves, together with other ancillary traits (large number and high flexibility of leaves, caudices, and/or epiphytism) which constitute the "narrow-leaf syndrome" should increase fog-interception efficiency. This was tested using aluminum models of rosettes that differed in leaf length, width and number and were exposed to artificial fog. The results were validated using seven species of Tillandsia and four species of xerophytic rosettes. The total amount of fog intercepted in rosette plants increased with total leaf area, while narrow leaves maximized interception efficiency (measured as interception per unit area). The number of leaves in the rosettes is physically constrained because wide-leafed plants can only have a few blades. At the limits of this constraint, net fog interception was independent of leaf form, but interception efficiency was maximized by large numbers of narrow leaves. Atmospheric Tillandsia species show the narrow-leaf syndrome. Their fog interception efficiencies were correlated to the ones predicted from aluminum-model data. In the larger xerophytic rosette species, the interception efficiency was greatest in plants showing the narrow-leaf syndrome. The adaptation to fog-harvesting in several narrow-leaved rosettes was tested for evolutionary convergence in 30 xerophytic rosette species using a comparative method. There was a significant evolutionary tendency towards the development of the narrow-leaf syndrome the closer the species grew to areas where fog is frequently available. This study establishes convergence in a very wide group of plants encompassing genera as contrasting as Tillandsia and Agave as a result of their dependence on fog.

Evaporation of impact water droplets in interception processes: Historical precedence of the hypothesis and a brief literature overview

NASA Astrophysics Data System (ADS)

Dunkerley, David L.

2009-10-01

SummaryIntra-storm evaporation depths exceed post-storm evaporation depths in the interception of rainfall on plant canopies. An important fraction of the intra-storm evaporation may involve the small impact (or splash) droplets produced when raindrops, and perhaps gravity drops (drips released from plant parts), collide with wet plant surfaces. This idea has been presented as a new conception by Murakami [Murakami, S., 2006. A proposal for a new forest canopy interception mechanism: splash droplet evaporation. Journal of Hydrology 319, 72-82; Murakami, S., 2007a. Application of three canopy interception models to a young stand of Japanese cypress and interpretation in terms of interception mechanism. Journal of Hydrology 342, 305-319; Murakami, S., 2007b. A follow-up for the splash droplet evaporation hypothesis of canopy interception and remaining problems: why is humidity unsaturated during rainfall? In: Proceedings of the 20th Annual Conference. Japan Society of Hydrology and Water Resources (in Japanese). < http://www.jstage.jst.go.jp/article/jshwr/20/0/20_62/_article>] but was in fact advanced by Dunin [Dunin, F.X., O'Loughlin, E.M., Reyenga, W., 1988. Interception loss from eucalypt forest: lysimeter determination of hourly rates for long term evaluation. Hydrological Processes 2, 315-329] more than 20 years ago. In addition, Dunin et al. considered that canopy ventilation might be enhanced in intense rain. This note draws attention to the historical precedence of the work of Dunin et al. and also presents a short review of literature on impact droplet production, highlighting areas where data are still required for the full exploration of the role of droplet evaporation in canopy interception. Droplet production needs to be properly parameterised and included in models of interception processes and landsurface-atmosphere interactions.

Rainfall interception from a lowland tropical rainforest in Brunei

NASA Astrophysics Data System (ADS)

Dykes, A. P.

1997-12-01

Results from a programme of throughfall measurements in a lowland tropical rainforest in Brunei, northwest Borneo, indicate that interception losses amount to 18% of the gross incident rainfall. The high annual rainfall experienced by the study area results in annual interception losses of around 800 mm, which may result in total annual evapotranspiration losses significantly higher than in other rainforest locations. An improved version of Gash's analytical interception model is tested on the available data using assumed values for the "forest" parameters, and is found to predict interception losses extremely well. The model predictions are based on an estimated evaporation rate during rainfall of 0.71 mm h -1. This is significantly higher than has been reported in other tropical studies. It is concluded that these results are distinctive when compared with previous results from rainforests, and that further, detailed work is required to establish whether the enhanced evaporation rate is due to advective effects associated with the maritime setting of the study area.

Identifying crash-prone traffic conditions under different weather on freeways.

PubMed

Xu, Chengcheng; Wang, Wei; Liu, Pan

2013-09-01

Understanding the relationships between traffic flow characteristics and crash risk under adverse weather conditions will help highway agencies develop proactive safety management strategies to improve traffic safety in adverse weather conditions. The primary objective is to develop separate crash risk prediction models for different weather conditions. The crash data, weather data, and traffic data used in this study were collected on the I-880N freeway in California in 2008 and 2010. This study considered three different weather conditions: clear weather, rainy weather, and reduced visibility weather. The preliminary analysis showed that there was some heterogeneity in the risk estimates for traffic flow characteristics by weather conditions, and that the crash risk prediction model for all weather conditions cannot capture the impacts of the traffic flow variables on crash risk under adverse weather conditions. The Bayesian random intercept logistic regression models were applied to link the likelihood of crash occurrence with various traffic flow characteristics under different weather conditions. The crash risk prediction models were compared to their corresponding logistic regression model. It was found that the random intercept model improved the goodness-of-fit of the crash risk prediction models. The model estimation results showed that the traffic flow characteristics contributing to crash risk were different across different weather conditions. The speed difference between upstream and downstream stations was found to be significant in each crash risk prediction model. Speed difference between upstream and downstream stations had the largest impact on crash risk in reduced visibility weather, followed by that in rainy weather. The ROC curves were further developed to evaluate the predictive performance of the crash risk prediction models under different weather conditions. The predictive performance of the crash risk model for clear weather was better than those of the crash risk models for adverse weather conditions. The research results could promote a better understanding of the impacts of traffic flow characteristics on crash risk under adverse weather conditions, which will help transportation professionals to develop better crash prevention strategies in adverse weather. Copyright © 2013 National Safety Council and Elsevier Ltd. All rights reserved.

Mathematical model for the contribution of individual organs to non-zero y-intercepts in single and multi-compartment linear models of whole-body energy expenditure.

PubMed

Kaiyala, Karl J

2014-01-01

Mathematical models for the dependence of energy expenditure (EE) on body mass and composition are essential tools in metabolic phenotyping. EE scales over broad ranges of body mass as a non-linear allometric function. When considered within restricted ranges of body mass, however, allometric EE curves exhibit 'local linearity.' Indeed, modern EE analysis makes extensive use of linear models. Such models typically involve one or two body mass compartments (e.g., fat free mass and fat mass). Importantly, linear EE models typically involve a non-zero (usually positive) y-intercept term of uncertain origin, a recurring theme in discussions of EE analysis and a source of confounding in traditional ratio-based EE normalization. Emerging linear model approaches quantify whole-body resting EE (REE) in terms of individual organ masses (e.g., liver, kidneys, heart, brain). Proponents of individual organ REE modeling hypothesize that multi-organ linear models may eliminate non-zero y-intercepts. This could have advantages in adjusting REE for body mass and composition. Studies reveal that individual organ REE is an allometric function of total body mass. I exploit first-order Taylor linearization of individual organ REEs to model the manner in which individual organs contribute to whole-body REE and to the non-zero y-intercept in linear REE models. The model predicts that REE analysis at the individual organ-tissue level will not eliminate intercept terms. I demonstrate that the parameters of a linear EE equation can be transformed into the parameters of the underlying 'latent' allometric equation. This permits estimates of the allometric scaling of EE in a diverse variety of physiological states that are not represented in the allometric EE literature but are well represented by published linear EE analyses.

The relationship between sense of community in the school and students' aggressive behavior: A multilevel analysis.

PubMed

Prati, Gabriele; Albanesi, Cinzia; Cicognani, Elvira

2018-06-18

School sense of community has been associated with lower levels of students' aggressive behaviors. The main aim of the study was to examine whether the magnitude of the influence of school sense of community on students' aggressive behavior is similar or different across schools with different levels of aggressive behaviors. Participants were 1,800 Italian students attending 44 middle and high schools. Using multilevel modeling (a random intercepts and slopes model), we found that the magnitude of the negative relationship between sense of community in the school and students' aggressive behaviors was stronger in schools with high levels of aggressive behavior. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Contrasting plant height can improve the control of rain-borne diseases in wheat cultivar mixture: modelling splash dispersal in 3-D canopies.

PubMed

Vidal, T; Gigot, C; de Vallavieille-Pope, C; Huber, L; Saint-Jean, S

2018-06-08

Growing cultivars differing by their disease resistance level together (cultivar mixtures) can reduce the propagation of diseases. Although architectural characteristics of cultivars are little considered in mixture design, they could have an effect on disease, in particular through spore dispersal by rain splash, which occurs over short distances. The objective of this work was to assess the impact of plant height of wheat cultivars in mixtures on splash dispersal of Zymoseptoria tritici, which causes septoria tritici leaf blotch. We used a modelling approach involving an explicit description of canopy architecture and splash dispersal processes. The dispersal model computed raindrop interception by a virtual canopy as well as the production, transport and interception of splash droplets carrying inoculum. We designed 3-D virtual canopies composed of susceptible and resistant plants, according to field measurements at the flowering stage. In numerical experiments, we tested different heights of virtual cultivars making up binary mixtures to assess the influence of this architectural trait on dispersal patterns of spore-carrying droplets. Inoculum interception decreased exponentially with the height relative to the main inoculum source (lower diseased leaves of susceptible plants), and little inoculum was intercepted further than 40 cm above the inoculum source. Consequently, tall plants intercepted less inoculum than smaller ones. Plants with twice the standard height intercepted 33 % less inoculum than standard height plants. In cases when the height of suscpeptible plants was doubled, inoculum interception by resistant leaves was 40 % higher. This physical barrier to spore-carrying droplet trajectories reduced inoculum interception by tall susceptible plants and was modulated by plant height differences between cultivars of a binary mixture. These results suggest that mixture effects on spore dispersal could be modulated by an adequate choice of architectural characteristics of cultivars. In particular, even small differences in plant height could reduce spore dispersal.

Mean-intercept anisotropy analysis of porous media. II. Conceptual shortcomings of the MIL tensor definition and Minkowski tensors as an alternative.

PubMed

Klatt, Michael A; Schröder-Turk, Gerd E; Mecke, Klaus

2017-07-01

Structure-property relations, which relate the shape of the microstructure to physical properties such as transport or mechanical properties, need sensitive measures of structure. What are suitable fabric tensors to quantify the shape of anisotropic heterogeneous materials? The mean intercept length is among the most commonly used characteristics of anisotropy in porous media, e.g., of trabecular bone in medical physics. Yet, in this series of two papers we demonstrate that it has conceptual shortcomings that limit the validity of its results. We test the validity of general assumptions regarding the properties of the mean-intercept length tensor using analytical formulas for the mean-intercept lengths in anisotropic Boolean models (derived in part I of this series), augmented by numerical simulations. We discuss in detail the functional form of the mean intercept length as a function of the test line orientations. As the most prominent result, we find that, at least for the example of overlapping grains modeling porous media, the polar plot of the mean intercept length is in general not an ellipse and hence not represented by a second-rank tensor. This is in stark contrast to the common understanding that for a large collection of grains the mean intercept length figure averages to an ellipse. The standard mean intercept length tensor defined by a least-square fit of an ellipse is based on a model mismatch, which causes an intrinsic lack of accuracy. Our analysis reveals several shortcomings of the mean intercept length tensor analysis that pose conceptual problems and limitations on the information content of this commonly used analysis method. We suggest the Minkowski tensors from integral geometry as alternative sensitive measures of anisotropy. The Minkowski tensors allow for a robust, comprehensive, and systematic approach to quantify various aspects of structural anisotropy. We show the Minkowski tensors to be more sensitive, in the sense, that they can quantify the remnant anisotropy of structures not captured by the mean intercept length analysis. If applied to porous tissue and microstructures, this improved structure characterization can yield new insights into the relationships between geometry and material properties. © 2017 American Association of Physicists in Medicine.

Satellite-based prediction of rainfall interception by tropical forest stands of a human-dominated landscape in Central Sulawesi, Indonesia

NASA Astrophysics Data System (ADS)

Nieschulze, Jens; Erasmi, Stefan; Dietz, Johannes; Hölscher, Dirk

2009-01-01

SummaryRainforest conversion to other land use types drastically alters the hydrological cycle in which changes in rainfall interception contribute significantly to the observed differences. However, little is known about the effects of more gradual changes in forest structure and at regional scales. We studied land use types ranging from natural forest over selectively-logged forest to cacao agroforest in a lower montane region in Central Sulawesi, Indonesia, and tested the suitability of high-resolution optical satellite imagery for modeling observed interception patterns. Investigated characteristics indicating canopy structure were mean and standard deviation of reflectance values, local maxima, and self-similarity measures based on the grey level co-occurrence matrix and geostatistical variogram analysis. Previously studied and published rainfall interception data comprised twelve plots and median values per land use type ranged from 30% in natural forest to 18% in cacao agroforests. A linear regression model with local maxima, mean contrast and normalized digital vegetation index (NDVI) as regressors was able to explain more than 84% ( Radj2) of the variation encountered in the data. Other investigated characteristics did not prove significant in the regression analysis. The model yielded stable results with respect to cross-validation and also produced realistic values and spatial patterns when applied at the landscape level (783.6 ha). High values of interception were rare and localized in natural forest stands distant to villages, whereas low interception characterized the intensively used sites close to settlements. We conclude that forest use intensity significantly reduced rainfall interception and satellite image analysis can successfully be applied for its regional prediction, and most forest in the study region has already been subject to human-induced structural changes.

A 3-level Bayesian mixed effects location scale model with an application to ecological momentary assessment data.

PubMed

Lin, Xiaolei; Mermelstein, Robin J; Hedeker, Donald

2018-06-15

Ecological momentary assessment studies usually produce intensively measured longitudinal data with large numbers of observations per unit, and research interest is often centered around understanding the changes in variation of people's thoughts, emotions and behaviors. Hedeker et al developed a 2-level mixed effects location scale model that allows observed covariates as well as unobserved variables to influence both the mean and the within-subjects variance, for a 2-level data structure where observations are nested within subjects. In some ecological momentary assessment studies, subjects are measured at multiple waves, and within each wave, subjects are measured over time. Li and Hedeker extended the original 2-level model to a 3-level data structure where observations are nested within days and days are then nested within subjects, by including a random location and scale intercept at the intermediate wave level. However, the 3-level random intercept model assumes constant response change rate for both the mean and variance. To account for changes in variance across waves, as well as clustering attributable to waves, we propose a more comprehensive location scale model that allows subject heterogeneity at baseline as well as across different waves, for a 3-level data structure where observations are nested within waves and waves are then further nested within subjects. The model parameters are estimated using Markov chain Monte Carlo methods. We provide details on the Bayesian estimation approach and demonstrate how the Stan statistical software can be used to sample from the desired distributions and achieve consistent estimates. The proposed model is validated via a series of simulation studies. Data from an adolescent smoking study are analyzed to demonstrate this approach. The analyses clearly favor the proposed model and show significant subject heterogeneity at baseline as well as change over time, for both mood mean and variance. The proposed 3-level location scale model can be widely applied to areas of research where the interest lies in the consistency in addition to the mean level of the responses. Copyright © 2018 John Wiley & Sons, Ltd.

Seasonality on the rainfall partitioning of a fast-growing tree plantation under Mediterranean conditions

NASA Astrophysics Data System (ADS)

molina, antonio; llorens, pilar; biel, carme

2014-05-01

Studies on rainfall interception in fast-growing tree plantations are less numerous than those in natural forests. Trees in these plantations are regularly distributed, and the canopy cover is clumped but changes quickly, resulting on high variability in the volume and composition of water that reach the soil. In addition, irrigation supply is normally required in semiarid areas to get optimal wood production; consequently, knowing rainfall interception and its yearly evolution is crucial to manage the irrigation scheme properly. This work studies the rainfall partitioning seasonality in a cherry tree (Prunus avium) plantation orientated to timber production under Mediterranean conditions. The monitoring design started on March 2012 and consists of a set of 58 throughfall tipping buckets randomly distributed (based on a 1x1 m2 grid) in a plot of 128 m2 with 8 trees. Stemflow is measured in all the trees with 2 tipping buckets and 6 accumulative collectors. Canopy cover is regularly measured throughout the study period, in leaf and leafless periods, by mean of sky-orientated photographs taken 50 cm above the center of each tipping bucket. Others tree biometrics are also measured such as diameter and leaf area index. Meteorological conditions are measured at 2 m above the forest cover. This work presents the first analyses describing the rainfall partitioning and its dependency on canopy cover, distance to tree and meteorological conditions. The modified Gash' model for rainfall interception in dispersed vegetation is also preliminary evaluated.

Intrastorm scale rainfall interception dynamics in a mature coniferous forest stand

NASA Astrophysics Data System (ADS)

Iida, Shin'ichi; Levia, Delphis F.; Shimizu, Akira; Shimizu, Takanori; Tamai, Koji; Nobuhiro, Tatsuhiko; Kabeya, Naoki; Noguchi, Shoji; Sawano, Shinji; Araki, Makoto

2017-05-01

Canopy interception of rainfall is an important process in the water balance of forests. The intrastorm dynamics of canopy interception is less well understood than event scale interception. Accordingly, armed with measurements of hourly interception intensity (i) from the field, this study is among the first to examine the differences in canopy interception dynamics between the first and second halves of rainfall events to quantify dynamic storage values for a coniferous forest in Japan. At this site, experimental results demonstrated that: (1) the relationship between interception loss (I) and gross rainfall (GR) at the event scale is better explained by a parabolic curve than a linear relationship, and there is a low correlation between rainfall intensity (gr) and i; (2) the ratio of accumulated i during the first half (IF) to that of gr (GRF) was larger than the second half (IS/GRS), with no significant correlations between potential evaporation during first half (PEF) vs IF or the second half (PES) vs IS; and (3) water storage capacity was similar to the magnitude of maximum I. By emphasizing the comparison between IF and IS, this study concludes that the water storage on tree surface is more important than losses by wet canopy evaporation and splash during rain. This study also adds insights into intrastorm interception dynamics of coniferous forests which are necessary to better model and forecast interception losses.

Modeling the rate of HIV testing from repeated binary data amidst potential never-testers.

PubMed

Rice, John D; Johnson, Brent A; Strawderman, Robert L

2018-01-04

Many longitudinal studies with a binary outcome measure involve a fraction of subjects with a homogeneous response profile. In our motivating data set, a study on the rate of human immunodeficiency virus (HIV) self-testing in a population of men who have sex with men (MSM), a substantial proportion of the subjects did not self-test during the follow-up study. The observed data in this context consist of a binary sequence for each subject indicating whether or not that subject experienced any events between consecutive observation time points, so subjects who never self-tested were observed to have a response vector consisting entirely of zeros. Conventional longitudinal analysis is not equipped to handle questions regarding the rate of events (as opposed to the odds, as in the classical logistic regression model). With the exception of discrete mixture models, such methods are also not equipped to handle settings in which there may exist a group of subjects for whom no events will ever occur, i.e. a so-called "never-responder" group. In this article, we model the observed data assuming that events occur according to some unobserved continuous-time stochastic process. In particular, we consider the underlying subject-specific processes to be Poisson conditional on some unobserved frailty, leading to a natural focus on modeling event rates. Specifically, we propose to use the power variance function (PVF) family of frailty distributions, which contains both the gamma and inverse Gaussian distributions as special cases and allows for the existence of a class of subjects having zero frailty. We generalize a computational algorithm developed for a log-gamma random intercept model (Conaway, 1990. A random effects model for binary data. Biometrics46, 317-328) to compute the exact marginal likelihood, which is then maximized to obtain estimates of model parameters. We conduct simulation studies, exploring the performance of the proposed method in comparison with competitors. Applying the PVF as well as a Gaussian random intercept model and a corresponding discrete mixture model to our motivating data set, we conclude that the group assigned to receive follow-up messages via SMS was self-testing at a significantly lower rate than the control group, but that there is no evidence to support the existence of a group of never-testers. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

DS/LPI autocorrelation detection in noise plus random-tone interference. [Direct Sequence Low-Probabilty of Intercept

NASA Technical Reports Server (NTRS)

Hinedi, S.; Polydoros, A.

1988-01-01

The authors present and analyze a frequency-noncoherent two-lag autocorrelation statistic for the wideband detection of random BPSK signals in noise-plus-random-multitone interference. It is shown that this detector is quite robust to the presence or absence of interference and its specific parameter values, contrary to the case of an energy detector. The rule assumes knowledge of the data rate and the active scenario under H0. It is concluded that the real-time autocorrelation domain and its samples (lags) are a viable approach for detecting random signals in dense environments.

Spectral estimates of solar radiation intercepted by corn canopies

NASA Technical Reports Server (NTRS)

Bauer, M. E. (Principal Investigator); Daughtry, C. S. T.; Gallo, K. P.

1982-01-01

Reflectance factor data were acquired with a Landsat band radiometer throughout two growing seasons for corn (Zea mays L.) canopies differing in planting dates, populations, and soil types. Agronomic data collected included leaf area index (LAI), biomass, development stage, and final grain yields. The spectral variable, greenness, was associated with 78 percent of the variation in LAI over all treatments. Single observations of LAI or greenness have limited value in predicting corn yields. The proportions of solar radiation intercepted (SRI) by these canopies were estimated using either measured LAI or greenness. Both SRI estimates, when accumulated over the growing season, accounted for approximately 65 percent of the variation in yields. Models which simulated the daily effects of weather and intercepted solar radiation on growth had the highest correlations to grain yields. This concept of estimating intercepted solar radiation using spectral data represents a viable approach for merging spectral and meteorological data for crop yield models.

LiDAR based prediction of forest biomass using hierarchical models with spatially varying coefficients

USGS Publications Warehouse

Babcock, Chad; Finley, Andrew O.; Bradford, John B.; Kolka, Randall K.; Birdsey, Richard A.; Ryan, Michael G.

2015-01-01

Many studies and production inventory systems have shown the utility of coupling covariates derived from Light Detection and Ranging (LiDAR) data with forest variables measured on georeferenced inventory plots through regression models. The objective of this study was to propose and assess the use of a Bayesian hierarchical modeling framework that accommodates both residual spatial dependence and non-stationarity of model covariates through the introduction of spatial random effects. We explored this objective using four forest inventory datasets that are part of the North American Carbon Program, each comprising point-referenced measures of above-ground forest biomass and discrete LiDAR. For each dataset, we considered at least five regression model specifications of varying complexity. Models were assessed based on goodness of fit criteria and predictive performance using a 10-fold cross-validation procedure. Results showed that the addition of spatial random effects to the regression model intercept improved fit and predictive performance in the presence of substantial residual spatial dependence. Additionally, in some cases, allowing either some or all regression slope parameters to vary spatially, via the addition of spatial random effects, further improved model fit and predictive performance. In other instances, models showed improved fit but decreased predictive performance—indicating over-fitting and underscoring the need for cross-validation to assess predictive ability. The proposed Bayesian modeling framework provided access to pixel-level posterior predictive distributions that were useful for uncertainty mapping, diagnosing spatial extrapolation issues, revealing missing model covariates, and discovering locally significant parameters.

Muscular Proprioception Contributes to the Control of Interceptive Actions

ERIC Educational Resources Information Center

Bastin, Julien; Calvin, Sarah; Montagne, Gilles

2006-01-01

The authors proposed a model of the control of interceptive action over a ground plane (Chardenon, Montagne, Laurent, & Bootsma, 2004). This model is based on the cancellation of the rate of change of the angle between the current position of the target and the direction of displacement (i.e., the bearing angle). While several sources of visual…

Hypothesis testing of a change point during cognitive decline among Alzheimer's disease patients.

PubMed

Ji, Ming; Xiong, Chengjie; Grundman, Michael

2003-10-01

In this paper, we present a statistical hypothesis test for detecting a change point over the course of cognitive decline among Alzheimer's disease patients. The model under the null hypothesis assumes a constant rate of cognitive decline over time and the model under the alternative hypothesis is a general bilinear model with an unknown change point. When the change point is unknown, however, the null distribution of the test statistics is not analytically tractable and has to be simulated by parametric bootstrap. When the alternative hypothesis that a change point exists is accepted, we propose an estimate of its location based on the Akaike's Information Criterion. We applied our method to a data set from the Neuropsychological Database Initiative by implementing our hypothesis testing method to analyze Mini Mental Status Exam scores based on a random-slope and random-intercept model with a bilinear fixed effect. Our result shows that despite large amount of missing data, accelerated decline did occur for MMSE among AD patients. Our finding supports the clinical belief of the existence of a change point during cognitive decline among AD patients and suggests the use of change point models for the longitudinal modeling of cognitive decline in AD research.

Effects of the interception of litterfall by the understory on carbon cycling in eucalyptus plantations of South China.

PubMed

Yang, Long; Wang, Jun; Huang, Yuhui; Hui, Dafeng; Wen, Meili

2014-01-01

For the purposes of forest restoration, carbon (C) fixation, and economic improvement, eucalyptus (Eucalyptus urophylla) has been widely planted in South China. The understory of eucalyptus plantations is often occupied by a dense community of the fern Dicranopteris dichotoma, which intercepts tree canopy leaf litter before it reaches the ground. To understand the effects of this interception of litterfall on C cycling in eucalyptus plantations, we quantified the mass of intercepted litter and the influences of litterfall interception on litter decomposition and soil respiration. The total mass of E. urophylla litterfall collected on the understory was similar to that collected by the traditional litter trap method. All of the eucalyptus litterfall is intercepted by the D. dichotoma canopy. Of the litterfall that was intercepted by D. dichotoma, 20-40% and 60-80% was intercepted by the top (50-100 cm) and bottom (0-50 cm) of the understory canopy, respectively. Intercepted litterfall decomposed faster at the bottom of understory canopy (at the base of the plants) than at the top, and decomposition was slower on the soil surface in the absence of understory than on any location in the understory canopy. Soil respiration was highest when both the understory and litter were present and was lowest when both the understory and litter were absent. These results indicate that litterfall interception changed carbon flow between aboveground and belowground through litter decomposition and soil respiration, which changed carbon cycling in eucalyptus plantations. The effects of the understory on litter decomposition and soil respiration should be considered in ecosystem carbon models.

Mathematical Model for the Contribution of Individual Organs to Non-Zero Y-Intercepts in Single and Multi-Compartment Linear Models of Whole-Body Energy Expenditure

PubMed Central

Kaiyala, Karl J.

2014-01-01

Mathematical models for the dependence of energy expenditure (EE) on body mass and composition are essential tools in metabolic phenotyping. EE scales over broad ranges of body mass as a non-linear allometric function. When considered within restricted ranges of body mass, however, allometric EE curves exhibit ‘local linearity.’ Indeed, modern EE analysis makes extensive use of linear models. Such models typically involve one or two body mass compartments (e.g., fat free mass and fat mass). Importantly, linear EE models typically involve a non-zero (usually positive) y-intercept term of uncertain origin, a recurring theme in discussions of EE analysis and a source of confounding in traditional ratio-based EE normalization. Emerging linear model approaches quantify whole-body resting EE (REE) in terms of individual organ masses (e.g., liver, kidneys, heart, brain). Proponents of individual organ REE modeling hypothesize that multi-organ linear models may eliminate non-zero y-intercepts. This could have advantages in adjusting REE for body mass and composition. Studies reveal that individual organ REE is an allometric function of total body mass. I exploit first-order Taylor linearization of individual organ REEs to model the manner in which individual organs contribute to whole-body REE and to the non-zero y-intercept in linear REE models. The model predicts that REE analysis at the individual organ-tissue level will not eliminate intercept terms. I demonstrate that the parameters of a linear EE equation can be transformed into the parameters of the underlying ‘latent’ allometric equation. This permits estimates of the allometric scaling of EE in a diverse variety of physiological states that are not represented in the allometric EE literature but are well represented by published linear EE analyses. PMID:25068692

An Efficient Ray-Tracing Method for Determining Terrain Intercepts in EDL Simulations

NASA Technical Reports Server (NTRS)

Shidner, Jeremy D.

2016-01-01

The calculation of a ray's intercept from an arbitrary point in space to a prescribed surface is a common task in computer simulations. The arbitrary point often represents an object that is moving according to the simulation, while the prescribed surface is fixed in a defined frame. For detailed simulations, this surface becomes complex, taking the form of real-world objects such as mountains, craters or valleys which require more advanced methods to accurately calculate a ray's intercept location. Incorporation of these complex surfaces has commonly been implemented in graphics systems that utilize highly optimized graphics processing units to analyze such features. This paper proposes a simplified method that does not require computationally intensive graphics solutions, but rather an optimized ray-tracing method for an assumed terrain dataset. This approach was developed for the Mars Science Laboratory mission which landed on the complex terrain of Gale Crater. First, this paper begins with a discussion of the simulation used to implement the model and the applicability of finding surface intercepts with respect to atmosphere modeling, altitude determination, radar modeling, and contact forces influencing vehicle dynamics. Next, the derivation and assumptions of the intercept finding method are presented. Key assumptions are noted making the routines specific to only certain types of surface data sets that are equidistantly spaced in longitude and latitude. The derivation of the method relies on ray-tracing, requiring discussion on the formulation of the ray with respect to the terrain datasets. Further discussion includes techniques for ray initialization in order to optimize the intercept search. Then, the model implementation for various new applications in the simulation are demonstrated. Finally, a validation of the accuracy is presented along with the corresponding data sets used in the validation. A performance summary of the method will be shown using the analysis from the Mars Science Laboratory's terminal descent sensing model. Alternate uses will also be shown for determining horizon maps and orbiter set times.

A pragmatic approach for mortality prediction after surgery in infective endocarditis: optimizing and refining EuroSCORE.

PubMed

Fernández-Hidalgo, N; Ferreria-González, I; Marsal, J R; Ribera, A; Aznar, M L; de Alarcón, A; García-Cabrera, E; Gálvez-Acebal, J; Sánchez-Espín, G; Reguera-Iglesias, J M; De La Torre-Lima, J; Lomas, J M; Hidalgo-Tenorio, C; Vallejo, N; Miranda, B; Santos-Ortega, A; Castro, M A; Tornos, P; García-Dorado, D; Almirante, B

2018-03-03

To simplify and optimize the ability of EuroSCORE I and II to predict early mortality after surgery for infective endocarditis (IE). Multicentre retrospective study (n = 775). Simplified scores, eliminating irrelevant variables, and new specific scores, adding specific IE variables, were created. The performance of the original, recalibrated and specific EuroSCOREs was assessed by Brier score, C-statistic and calibration plot in bootstrap samples. The Net Reclassification Index was quantified. Recalibrated scores including age, previous cardiac surgery, critical preoperative state, New York Heart Association >I, and emergent surgery (EuroSCORE I and II); renal failure and pulmonary hypertension (EuroSCORE I); and urgent surgery (EuroSCORE II) performed better than the original EuroSCOREs (Brier original and recalibrated: EuroSCORE I: 0.1770 and 0.1667; EuroSCORE II: 0.2307 and 0.1680). Performance improved with the addition of fistula, staphylococci and mitral location (EuroSCORE I and II) (Brier specific: EuroSCORE I 0.1587, EuroSCORE II 0.1592). Discrimination improved in specific models (C-statistic original, recalibrated and specific: EuroSCORE I: 0.7340, 0.7471 and 0.7728; EuroSCORE II: 0.7442, 0.7423 and 0.7700). Calibration improved in both EuroSCORE I models (intercept 0.295, slope 0.829 (original); intercept -0.094, slope 0.888 (recalibrated); intercept -0.059, slope 0.925 (specific)) but only in specific EuroSCORE II model (intercept 2.554, slope 1.114 (original); intercept -0.260, slope 0.703 (recalibrated); intercept -0.053, slope 0.930 (specific)). Net Reclassification Index was 5.1% and 20.3% for the specific EuroSCORE I and II CONCLUSIONS: The use of simplified EuroSCORE I and EuroSCORE II models in IE with the addition of specific variables may lead to simpler and more accurate models. Copyright © 2018 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Fractional-order information in the visual control of lateral locomotor interception.

PubMed

Bootsma, Reinoud J; Ledouit, Simon; Casanova, Remy; Zaal, Frank T J M

2016-04-01

Previous work on locomotor interception of a target moving in the transverse plane has suggested that interception is achieved by maintaining the target's bearing angle (often inadvertently confused and/or confounded with the target heading angle) at a constant value. However, dynamics-based model simulations testing the veracity of the underlying control strategy of nulling the rate of change in the bearing angle have been restricted to limited conditions of target motion, and only a few alternatives have been considered. Exploring a wide range of target motion characteristics with straight and curving ball trajectories in a virtual reality setting, we examined how soccer goalkeepers moved along the goal line to intercept long-range shots on goal, a situation in which interception is naturally constrained to movement along a single dimension. Analyses of the movement patterns suggested reliance on combinations of optical position and velocity for straight trajectories and optical velocity and acceleration for curving trajectories. As an alternative to combining such standard integer-order derivatives, we demonstrate with a simple dynamical model that nulling a single informational variable of a self-tuned fractional (rather than integer) order efficiently captures the timing and patterning of the observed interception behaviors. This new perspective could fundamentally change the conception of what perceptual systems may actually provide, both in humans and in other animals. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Rainfall interception, and its modeling, in Pine and Eucalypt stands in Portugal

NASA Astrophysics Data System (ADS)

de Coninck, H. L.; Keizer, J. J.; Coelho, C. O. A.; van Dijck, S. J. E.; Jetten, V. G.; Warmerdam, P. M. M.; Ferreira, A. J. D.; Boulet, A. K.

2003-04-01

Within the framework of the EU-funded CLIMED project (ICA3-2000-30005), concerning the water management implications of foreseeable climate and land-use changes in central Portugal and northern Africa, the event-based Limburg Soil Erosion Model (LISEM; www.geog.uu.nl/lisem) is intended to provide further insight into water yields, peak flow and timing under possible future rainfall regimes. In the Portuguese study area, LISEM is being applied to two small (< 1km2) catchments with contrasting land covers, dominated by Pinus pinaster Ait. and Eucalyptus globulus Labill. tree stands, respectively. In LISEM, cumulative interception is modelled using the empirical formula by Ashton (1979), i.e. as a function of vegetation cover and canopy storage capacity, which in turn is estimated from the Leaf Area Index using the Von Hoyningen-Huenes (1981) formula. Besides that the appropriateness of the LISEM interception module for forested areas may be questioned, its (optional) substitution in LISEM by a more process-based model like that of Rutter would be more in line with LISEM’s overall model structure. This study has as main aims to assess the suitability of (1) the Ashton formula and (2) the sparse variants of the Gash and Rutter interception models to model rainfall interception measurements carried out in a Pinus pinaster Ait. stand as well as a Eucalyptus globulus Labill. stand. Unlike in the bulk of published studies on forest interception, the experimental set-up structures the sampling space in below-canopy and gaps. The below-canopy sampling space is further divided into two classes on the basis of dendrometric data from a prior inventory of 20x20 m. The two stands are equipped with 15 below-canopy and 5 gap rainfall collectors, 3 of which are automated tipping-buckets gauges. Stemflow is measured for 10 trees per stand, which includes 2 trees with automated tipping-bucket (0.5 l/tip). Between November 2002 and the present time, 31 rainfall events totaling about 850 mm were recorded. Interestingly, these preliminary results reveal that below-canopy rainfall may exceed gap rainfall. This phenomenon can be explained by non-vertical rainfall, increasing the probability of droplets hitting the tree canopy instead of the forest floor. If further measurements confirm it to occur regularly, the suitability of not only the LISEM interception module but also the sparse Rutter and Gash models will, at least conceptually, be in doubt.

Plant light interception can be explained via computed tomography scanning: demonstration with pyramidal cedar (Thuja occidentalis, Fastigiata).

PubMed

Dutilleul, Pierre; Han, Liwen; Smith, Donald L

2008-01-01

Light interception by the leaf canopy is a key aspect of plant photosynthesis, which helps mitigate the greenhouse effect via atmospheric CO(2) recycling. The relationship between plant light interception and leaf area was traditionally modelled with the Beer-Lambert law, until the spatial distribution of leaves was incorporated through the fractal dimension of leafless plant structure photographed from the side allowing maximum appearance of branches and petioles. However, photographs of leafless plants are two-dimensional projections of three-dimensional structures, and sampled plants were cut at the stem base before leaf blades were detached manually, so canopy development could not be followed for individual plants. Therefore, a new measurement and modelling approach were developed to explain plant light interception more completely and precisely, based on appropriate processing of computed tomography (CT) scanning data collected for developing canopies. Three-dimensional images of canopies were constructed from CT scanning data. Leaf volumes (LV) were evaluated from complete canopy images, and fractal dimensions (FD) were estimated from skeletonized leafless images. The experimental plant species is pyramidal cedar (Thuja occidentalis, Fastigiata). The three-dimensional version of the Beer-Lambert law based on FD alone provided a much better explanation of plant light interception (R(2) = 0.858) than those using the product LV*FD (0.589) or LV alone (0.548). While values of all three regressors were found to increase over time, FD in the Beer-Lambert law followed the increase in light interception the most closely. The delayed increase of LV reflected the appearance of new leaves only after branches had lengthened and ramified. The very strong correlation obtained with FD demonstrates that CT scanning data contain fundamental information about the canopy architecture geometry. The model can be used to identify crops and plantation trees with improved light interception and productivity.

Plant Light Interception Can Be Explained via Computed Tomography Scanning: Demonstration with Pyramidal Cedar (Thuja occidentalis, Fastigiata)

PubMed Central

Dutilleul, Pierre; Han, Liwen; Smith, Donald L.

2008-01-01

Background and Aims Light interception by the leaf canopy is a key aspect of plant photosynthesis, which helps mitigate the greenhouse effect via atmospheric CO2 recycling. The relationship between plant light interception and leaf area was traditionally modelled with the Beer–Lambert law, until the spatial distribution of leaves was incorporated through the fractal dimension of leafless plant structure photographed from the side allowing maximum appearance of branches and petioles. However, photographs of leafless plants are two-dimensional projections of three-dimensional structures, and sampled plants were cut at the stem base before leaf blades were detached manually, so canopy development could not be followed for individual plants. Therefore, a new measurement and modelling approach were developed to explain plant light interception more completely and precisely, based on appropriate processing of computed tomography (CT) scanning data collected for developing canopies. Methods Three-dimensional images of canopies were constructed from CT scanning data. Leaf volumes (LV) were evaluated from complete canopy images, and fractal dimensions (FD) were estimated from skeletonized leafless images. The experimental plant species is pyramidal cedar (Thuja occidentalis, Fastigiata). Key Results The three-dimensional version of the Beer–Lambert law based on FD alone provided a much better explanation of plant light interception (R2 = 0·858) than those using the product LV*FD (0·589) or LV alone (0·548). While values of all three regressors were found to increase over time, FD in the Beer–Lambert law followed the increase in light interception the most closely. The delayed increase of LV reflected the appearance of new leaves only after branches had lengthened and ramified. Conclusions The very strong correlation obtained with FD demonstrates that CT scanning data contain fundamental information about the canopy architecture geometry. The model can be used to identify crops and plantation trees with improved light interception and productivity. PMID:17981879

The relationship between multilevel models and non-parametric multilevel mixture models: Discrete approximation of intraclass correlation, random coefficient distributions, and residual heteroscedasticity.

PubMed

Rights, Jason D; Sterba, Sonya K

2016-11-01

Multilevel data structures are common in the social sciences. Often, such nested data are analysed with multilevel models (MLMs) in which heterogeneity between clusters is modelled by continuously distributed random intercepts and/or slopes. Alternatively, the non-parametric multilevel regression mixture model (NPMM) can accommodate the same nested data structures through discrete latent class variation. The purpose of this article is to delineate analytic relationships between NPMM and MLM parameters that are useful for understanding the indirect interpretation of the NPMM as a non-parametric approximation of the MLM, with relaxed distributional assumptions. We define how seven standard and non-standard MLM specifications can be indirectly approximated by particular NPMM specifications. We provide formulas showing how the NPMM can serve as an approximation of the MLM in terms of intraclass correlation, random coefficient means and (co)variances, heteroscedasticity of residuals at level 1, and heteroscedasticity of residuals at level 2. Further, we discuss how these relationships can be useful in practice. The specific relationships are illustrated with simulated graphical demonstrations, and direct and indirect interpretations of NPMM classes are contrasted. We provide an R function to aid in implementing and visualizing an indirect interpretation of NPMM classes. An empirical example is presented and future directions are discussed. © 2016 The British Psychological Society.

What predicts recovery orientation in county departments of mental health? A pilot study.

PubMed

Brown, Timothy T; Mahoney, Christine B; Adams, Neal; Felton, Mistique; Pareja, Candy

2010-09-01

In this pilot study we examined the determinants of recovery orientation among employees and influential stakeholders in a sample of 12 county departments of mental health in California. A two-level hierarchical linear model with random intercepts was estimated. Analyses show that recovery orientation has a U-shaped relationship with the age of staff/influential stakeholders and is negatively related to the difference between the desired level of adhocracy and the current level of adhocracy. Recovery orientation is positively related to the education level of staff/influential stakeholders, satisfying transformational leadership outcomes, and larger mental health budgets per capita. Policy implications are discussed.

MIXOR: a computer program for mixed-effects ordinal regression analysis.

PubMed

Hedeker, D; Gibbons, R D

1996-03-01

MIXOR provides maximum marginal likelihood estimates for mixed-effects ordinal probit, logistic, and complementary log-log regression models. These models can be used for analysis of dichotomous and ordinal outcomes from either a clustered or longitudinal design. For clustered data, the mixed-effects model assumes that data within clusters are dependent. The degree of dependency is jointly estimated with the usual model parameters, thus adjusting for dependence resulting from clustering of the data. Similarly, for longitudinal data, the mixed-effects approach can allow for individual-varying intercepts and slopes across time, and can estimate the degree to which these time-related effects vary in the population of individuals. MIXOR uses marginal maximum likelihood estimation, utilizing a Fisher-scoring solution. For the scoring solution, the Cholesky factor of the random-effects variance-covariance matrix is estimated, along with the effects of model covariates. Examples illustrating usage and features of MIXOR are provided.

A cross-comparison of different techniques for modeling macro-level cyclist crashes.

PubMed

Guo, Yanyong; Osama, Ahmed; Sayed, Tarek

2018-04-01

Despite the recognized benefits of cycling as a sustainable mode of transportation, cyclists are considered vulnerable road users and there are concerns about their safety. Therefore, it is essential to investigate the factors affecting cyclist safety. The goal of this study is to evaluate and compare different approaches of modeling macro-level cyclist safety as well as investigating factors that contribute to cyclist crashes using a comprehensive list of covariates. Data from 134 traffic analysis zones (TAZs) in the City of Vancouver were used to develop macro-level crash models (CM) incorporating variables related to actual traffic exposure, socio-economics, land use, built environment, and bike network. Four types of CMs were developed under a full Bayesian framework: Poisson lognormal model (PLN), random intercepts PLN model (RIPLN), random parameters PLN model (RPPLN), and spatial PLN model (SPLN). The SPLN model had the best goodness of fit, and the results highlighted the significant effects of spatial correlation. The models showed that the cyclist crashes were positively associated with bike and vehicle exposure measures, households, commercial area density, and signal density. On the other hand, negative associations were found between cyclist crashes and some bike network indicators such as average edge length, average zonal slope, and off-street bike links. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of the Interception of Litterfall by the Understory on Carbon Cycling in Eucalyptus Plantations of South China

PubMed Central

Huang, Yuhui; Hui, Dafeng; Wen, Meili

2014-01-01

For the purposes of forest restoration, carbon (C) fixation, and economic improvement, eucalyptus (Eucalyptus urophylla) has been widely planted in South China. The understory of eucalyptus plantations is often occupied by a dense community of the fern Dicranopteris dichotoma, which intercepts tree canopy leaf litter before it reaches the ground. To understand the effects of this interception of litterfall on C cycling in eucalyptus plantations, we quantified the mass of intercepted litter and the influences of litterfall interception on litter decomposition and soil respiration. The total mass of E. urophylla litterfall collected on the understory was similar to that collected by the traditional litter trap method. All of the eucalyptus litterfall is intercepted by the D. dichotoma canopy. Of the litterfall that was intercepted by D. dichotoma, 20–40% and 60–80% was intercepted by the top (50–100 cm) and bottom (0–50 cm) of the understory canopy, respectively. Intercepted litterfall decomposed faster at the bottom of understory canopy (at the base of the plants) than at the top, and decomposition was slower on the soil surface in the absence of understory than on any location in the understory canopy. Soil respiration was highest when both the understory and litter were present and was lowest when both the understory and litter were absent. These results indicate that litterfall interception changed carbon flow between aboveground and belowground through litter decomposition and soil respiration, which changed carbon cycling in eucalyptus plantations. The effects of the understory on litter decomposition and soil respiration should be considered in ecosystem carbon models. PMID:24959853

Modelling rainfall interception by forests: a new method for estimating the canopy storage capacity

NASA Astrophysics Data System (ADS)

Pereira, Fernando; Valente, Fernanda; Nóbrega, Cristina

2015-04-01

Evaporation of rainfall intercepted by forests is usually an important part of a catchment water balance. Recognizing the importance of interception loss, several models of the process have been developed. A key parameter of these models is the canopy storage capacity (S), commonly estimated by the so-called Leyton method. However, this method is somewhat subjective in the selection of the storms used to derive S, which is particularly critical when throughfall is highly variable in space. To overcome these problems, a new method for estimating S was proposed in 2009 by Pereira et al. (Agricultural and Forest Meteorology, 149: 680-688), which uses information from a larger number of storms, is less sensitive to throughfall spatial variability and is consistent with the formulation of the two most widely used rainfall interception models, Gash analytical model and Rutter model. However, this method has a drawback: it does not account for stemflow (Sf). To allow a wider use of this methodology, we propose now a revised version which makes the estimation of S independent of the importance of stemflow. For the application of this new version we only need to establish a linear regression of throughfall vs. gross rainfall using data from all storms large enough to saturate the canopy. Two of the parameters used by the Gash and the Rutter models, pd (the drainage partitioning coefficient) and S, are then derived from the regression coefficients: pd is firstly estimated allowing then the derivation of S but, if Sf is not considered, S can be estimated making pd= 0. This new method was tested using data from a eucalyptus plantation, a maritime pine forest and a traditional olive grove, all located in Central Portugal. For both the eucalyptus and the pine forests pd and S estimated by this new approach were comparable to the values derived in previous studies using the standard procedures. In the case of the traditional olive grove, the estimates obtained by this methodology for pd and S allowed interception loss to be modelled with a normalized averaged error less than 4%. Globally, these results confirm that the method is more robust and certainly less subjective, providing adequate estimates for pd and S which, in turn, are crucial for a good performance of the interception models.

A randomized, controlled study of a healthy corner store initiative on the purchases of urban, low-income youth

PubMed Central

Lent, Michelle R.; Veur, Stephanie S. Vander; McCoy, Tara A.; Wojtanowski, Alexis C.; Sandoval, Brianna; Sherman, Sandy; Komaroff, Eugene; Foster, Gary D.

2014-01-01

Objective Although many initiatives exist to improve the availability of healthy foods in corner stores, few randomized trials have assessed their effects. This study evaluated, in a randomized, controlled trial, the effects of a first-generation healthy corner store intervention on students’ food and beverage purchases over a two-year period. Design and Methods Participants (n=767) were 4th-6th grade students. Ten schools and their nearby corner stores (n=24) were randomly assigned to the healthy corner store intervention or an assessment-only control. Intercept surveys directly assessed the nutritional characteristics of students’ corner store purchases at baseline, 1 and 2 years. Students’ weight and heights were measured at baseline, 1 and 2 years. Results There were no differences in energy content per intercept purchased from control or intervention schools at year 1 (p=0.12) or 2 (p=0.58). There were no differences between control and intervention students in BMI-z score (year 1, p=0.83; year 2, p=0. 98) or obesity prevalence (year 1, p=0.96; year 2, p=0.58). Conclusions A healthy corner store initiative did not result in significant changes in the energy content of corner store purchases or in continuous or categorical measures of obesity. These data will help to inform future interventions. PMID:25311881

The value of comparative research in major day surgery.

PubMed

Llop-Gironés, Alba; Vergara-Duarte, Montse; Sánchez, Josep Anton; Tarafa, Gemma; Benach, Joan

2017-05-19

To measure time trends in major day surgery rates according to hospital ownership and other hospital characteristics among the providers of the public healthcare network of Catalonia, Spain. Data from the Statistics of Health Establishments providing Inpatient Care. A generalized linear mixed model with Gaussian response and random intercept and random slopes. The greatest growth in the rate of major day surgery was observed among private for-profit hospitals: 42.9 (SD: 22.5) in 2009 versus 2.7 (SD: 6.7) in 1996. These hospitals exhibited a significant increase in major day surgery compared to public hospitals (coefficient 2; p-value <0.01) CONCLUSIONS: The comparative evaluation of hospital performance is a decisive tool to ensure that public resources are used as rationally and efficiently as possible. Copyright © 2017 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

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.

The influence of visual motion on interceptive actions and perception.

PubMed

Marinovic, Welber; Plooy, Annaliese M; Arnold, Derek H

2012-05-01

Visual information is an essential guide when interacting with moving objects, yet it can also be deceiving. For instance, motion can induce illusory position shifts, such that a moving ball can seem to have bounced past its true point of contact with the ground. Some evidence suggests illusory motion-induced position shifts bias pointing tasks to a greater extent than they do perceptual judgments. This, however, appears at odds with other findings and with our success when intercepting moving objects. Here we examined the accuracy of interceptive movements and of perceptual judgments in relation to simulated bounces. Participants were asked to intercept a moving disc at its bounce location by positioning a virtual paddle, and then to report where the disc had landed. Results showed that interceptive actions were accurate whereas perceptual judgments were inaccurate, biased in the direction of motion. Successful interceptions necessitated accurate information concerning both the location and timing of the bounce, so motor planning evidently had privileged access to an accurate forward model of bounce timing and location. This would explain why people can be accurate when intercepting a moving object, but lack insight into the accurate information that had guided their actions when asked to make a perceptual judgment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Quantification of the effects of architectural traits on dry mass production and light interception of tomato canopy under different temperature regimes using a dynamic functional–structural plant model

PubMed Central

Chen, Tsu-Wei; Nguyen, Thi My Nguyet; Kahlen, Katrin; Stützel, Hartmut

2014-01-01

There is increasing interest in evaluating the environmental effects on crop architectural traits and yield improvement. However, crop models describing the dynamic changes in canopy structure with environmental conditions and the complex interactions between canopy structure, light interception, and dry mass production are only gradually emerging. Using tomato (Solanum lycopersicum L.) as a model crop, a dynamic functional–structural plant model (FSPM) was constructed, parameterized, and evaluated to analyse the effects of temperature on architectural traits, which strongly influence canopy light interception and shoot dry mass. The FSPM predicted the organ growth, organ size, and shoot dry mass over time with high accuracy (>85%). Analyses of this FSPM showed that, in comparison with the reference canopy, shoot dry mass may be affected by leaf angle by as much as 20%, leaf curvature by up to 7%, the leaf length:width ratio by up to 5%, internode length by up to 9%, and curvature ratios and leaf arrangement by up to 6%. Tomato canopies at low temperature had higher canopy density and were more clumped due to higher leaf area and shorter internodes. Interestingly, dry mass production and light interception of the clumped canopy were more sensitive to changes in architectural traits. The complex interactions between architectural traits, canopy light interception, dry mass production, and environmental conditions can be studied by the dynamic FSPM, which may serve as a tool for designing a canopy structure which is ‘ideal’ in a given environment. PMID:25183746

Logit-normal mixed model for Indian Monsoon rainfall extremes

NASA Astrophysics Data System (ADS)

Dietz, L. R.; Chatterjee, S.

2014-03-01

Describing the nature and variability of Indian monsoon rainfall extremes is a topic of much debate in the current literature. We suggest the use of a generalized linear mixed model (GLMM), specifically, the logit-normal mixed model, to describe the underlying structure of this complex climatic event. Several GLMM algorithms are described and simulations are performed to vet these algorithms before applying them to the Indian precipitation data procured from the National Climatic Data Center. The logit-normal model was applied with fixed covariates of latitude, longitude, elevation, daily minimum and maximum temperatures with a random intercept by weather station. In general, the estimation methods concurred in their suggestion of a relationship between the El Niño Southern Oscillation (ENSO) and extreme rainfall variability estimates. This work provides a valuable starting point for extending GLMM to incorporate the intricate dependencies in extreme climate events.

Examining the canopy interception at a forest field site using cosmic-ray neutron detection

NASA Astrophysics Data System (ADS)

Andreasen, M.; Looms, M.; Christiansen, J. R.; Sonnenborg, T. O.; Stisen, S.; Jensen, K. H.

2017-12-01

Canopy interception, the amount of precipitation captured by the surface of plants and trees, is a key component of the water cycle as it constrains the water flux to the ground below vegetation. Forests have especially high interception capacities and therefore the interception loss often forms a considerable part of the total evapotranspiration. The canopy interception capacity is dependent on the size and structure of the vegetation, and the interception loss can vary substantial in time and space. Measuring the canopy interception loss directly is challenging and current methodologies only represent small areas and rely on indirect approaches. Improving methods to estimate canopy interception loss directly will forward the basic understanding of how vegetation structure interacts with the water cycle and hence prediction of evapotranspiration. The intensity of low-energy neutrons produced by cosmic-rays, measured above the ground surface, is sensitive to the hydrogen content in the upper decimeters of the ground and hence the soil moisture content from a radius of hundreds of meters in the horizontal direction. In order to advance the cosmic-ray neutron (CRN) soil moisture method and extend the application of the CRN method more research has recently focused on the signal of other hydrogen pools on the neutron intensity (e.g., vegetation and canopy interception). A recent study, based on neutron transport modeling, found that the ground level thermal neutron intensity (energy < 1 eV), and as a consequence also the thermal-to-epithermal neutron (T/E) ratio (epithermal energy > 1 eV), increased with increasing canopy interception. In this study, we test whether CRN measurements can be used to provide a direct measure of the canopy interception. Four sets of CR2000/B systems were installed below the canopy in an oak forest stand in Denmark. Each system holds a bare (primarily measuring thermal neutrons) and a moderated detector (primarily measuring epithermal neutrons). The measured T/E ratios are compared to independent canopy interception measurements, obtained from throughfall and precipitation measurements. Furthermore, T/E ratios are related to measurements from leaf wetness sensors, CRN soil moisture estimates, and the biomass density in the canopy derived from a mobile terrestrial laser scanner.

The relationship between energy expenditure and speed during pedestrian locomotion in birds: a morphological basis for the elevated y-intercept?

PubMed

Halsey, Lewis G

2013-06-01

The slope of the typically linear relationship between metabolic rate and walking speed represents the net cost of transport (NCOT). The extrapolated y-intercept is often greater than resting metabolic rate, thus representing a fixed cost associated with pedestrian transport including body maintenance costs. The full cause of the elevated y-intercept remains elusive and it could simply represent experimental stresses. The present literature-based study compares the mass-independent energetic cost of pedestrian locomotion in birds (excluding those with an upright posture, i.e. penguins), represented by the y-intercept, to a known predictor of cost of transport, hip height. Both phylogenetically informed and non-phylogenetically informed analyses were undertaken to determine if patterns of association between hip height, body mass, and the y-intercept are robust with respect to the method of analysis. Body mass and hip height were significant predictors of the y-intercept in the best phylogenetically-informed and non-phylogenetically informed models. Thus there is evidence that, in birds at least, the elevated y-intercept is a legitimate component of locomotion energy expenditure. Hip height is probably a good proxy of effective limb length and thus perhaps birds with greater hip heights have lower y-intercepts because their longer legs more efficiently accommodate body motion and/or because their limbs are more aligned with the ground reaction forces. Copyright © 2013 Elsevier Inc. All rights reserved.

Using a generalized linear mixed model approach to explore the role of age, motor proficiency, and cognitive styles in children's reach estimation accuracy.

PubMed

Caçola, Priscila M; Pant, Mohan D

2014-10-01

The purpose was to use a multi-level statistical technique to analyze how children's age, motor proficiency, and cognitive styles interact to affect accuracy on reach estimation tasks via Motor Imagery and Visual Imagery. Results from the Generalized Linear Mixed Model analysis (GLMM) indicated that only the 7-year-old age group had significant random intercepts for both tasks. Motor proficiency predicted accuracy in reach tasks, and cognitive styles (object scale) predicted accuracy in the motor imagery task. GLMM analysis is suitable to explore age and other parameters of development. In this case, it allowed an assessment of motor proficiency interacting with age to shape how children represent, plan, and act on the environment.

A new terminal guidance sensor system for asteroid intercept or rendezvous missions

NASA Astrophysics Data System (ADS)

Lyzhoft, Joshua; Basart, John; Wie, Bong

2016-02-01

This paper presents the initial conceptual study results of a new terminal guidance sensor system for asteroid intercept or rendezvous missions, which explores the use of visual, infrared, and radar devices. As was demonstrated by NASA's Deep Impact mission, visual cameras can be effectively utilized for hypervelocity intercept terminal guidance for a 5 kilometer target. Other systems such as Raytheon's EKV (Exoatmospheric Kill Vehicle) employ a different scheme that utilizes infrared target information to intercept ballistic missiles. Another example that uses infrared information is the NEOWISE telescope, which is used for asteroid detection and tracking. This paper describes the signal-to-noise ratio estimation problem for infrared sensors, minimum and maximum range of detection, and computational validation using GPU accelerated simulations. Small targets (50-100 m in diameter) are considered, and scaled polyhedron models of known objects, such as the Rosetta mission's Comet 67P/Churyumov-Gerasimenko, 101,955 Bennu, target of the OSIRIS-REx mission, and asteroid 433 Eros, are utilized. A parallelized ray tracing algorithm to simulate realistic surface-to-surface shadowing of a given celestial body is developed. By using the simulated models and parameters given from the formulation of the different sensors, impact mission scenarios are used to verify the feasibility for intercepting a small target.

Modelling the control of interceptive actions.

PubMed Central

Beek, P J; Dessing, J C; Peper, C E; Bullock, D

2003-01-01

In recent years, several phenomenological dynamical models have been formulated that describe how perceptual variables are incorporated in the control of motor variables. We call these short-route models as they do not address how perception-action patterns might be constrained by the dynamical properties of the sensory, neural and musculoskeletal subsystems of the human action system. As an alternative, we advocate a long-route modelling approach in which the dynamics of these subsystems are explicitly addressed and integrated to reproduce interceptive actions. The approach is exemplified through a discussion of a recently developed model for interceptive actions consisting of a neural network architecture for the online generation of motor outflow commands, based on time-to-contact information and information about the relative positions and velocities of hand and ball. This network is shown to be consistent with both behavioural and neurophysiological data. Finally, some problems are discussed with regard to the question of how the motor outflow commands (i.e. the intended movement) might be modulated in view of the musculoskeletal dynamics. PMID:14561342

The importance of radiation for semiempirical water-use efficiency models

NASA Astrophysics Data System (ADS)

Boese, Sven; Jung, Martin; Carvalhais, Nuno; Reichstein, Markus

2017-06-01

Water-use efficiency (WUE) is a fundamental property for the coupling of carbon and water cycles in plants and ecosystems. Existing model formulations predicting this variable differ in the type of response of WUE to the atmospheric vapor pressure deficit of water (VPD). We tested a representative WUE model on the ecosystem scale at 110 eddy covariance sites of the FLUXNET initiative by predicting evapotranspiration (ET) based on gross primary productivity (GPP) and VPD. We found that introducing an intercept term in the formulation increases model performance considerably, indicating that an additional factor needs to be considered. We demonstrate that this intercept term varies seasonally and we subsequently associate it with radiation. Replacing the constant intercept term with a linear function of global radiation was found to further improve model predictions of ET. Our new semiempirical ecosystem WUE formulation indicates that, averaged over all sites, this radiation term accounts for up to half (39-47 %) of transpiration. These empirical findings challenge the current understanding of water-use efficiency on the ecosystem scale.

The influence of sugarcane crop development on rainfall interception losses

NASA Astrophysics Data System (ADS)

Fernandes, Rafael Pires; Silva, Robson Willians da Costa; Salemi, Luiz Felippe; Andrade, Tatiana Morgan Berteli de; Moraes, Jorge Marcos de; Dijk, Albert I. J. M. Van; Martinelli, Luiz Antonio

2017-08-01

The expansion of sugarcane plantations in Brazil has raised concerns regarding its hydrological impacts. One of these impacts is related to rainfall interception, which can be expected to vary in response to substantial changes in canopy structure throughout the cropping cycle. We collected field measurements to determine interception losses and interpreted the observations using an adapted Gash model during different stages of a sugarcane ratoon cropping cycle. Cumulative gross rainfall (PG), throughfall (TF) and stemflow (SF) were measured biweekly, along with vegetation structure measurements of leaf area index (LAI) and plant height. For the first 300 days after the first harvest, the cumulative PG of 1095 mm was partitioned into 635 mm TF (58%) and 263 mm SF (24%). The inferred interception loss (IL) was 263 mm (24%). There was a gradual and clear increase in IL from 3% to 46% while partitioning between TF and SF also changed during ratoon regrowth. After model parameter optimisation, observed IL was simulated satisfactorily. Model estimates suggested that evaporation from the saturated canopy is the main IL pathway, followed by evaporation after storms. Plant architecture, LAI and meteorological conditions during the cropping cycle appeared the main factors determining IL.

Expected scientific results on ballistic spacecraft missions to comet Encke during the 1980 apparition

NASA Technical Reports Server (NTRS)

Mumma, M. J.

1976-01-01

Summarized are three proposed ballistic spacecraft missions to intercept P/Encke during the 1980 apparition. A baseline physical activity model for P/Encke is established and the performances of the neutral mass spectrometer and of the imaging experiment on each intercept mission are assessed.

Determination of Indicators of Ecological Change

DTIC Science & Technology

2004-09-01

simultaneously characterized parameters for more than one forest (e.g., Huber and Iroume, 2001; Tobón Marin et al., 2000). As parameters (e.g...necessary to apply the revised model for use in five forest biomes , 2) use the model to predict precipitation interception and compare the measured and...larger interception losses than many other forest biomes . The within plot sampling coefficient of variation, ranging from a study average of 0.11 in

Two zero-flow pressure intercepts exist in autoregulating isolated skeletal muscle.

PubMed

Braakman, R; Sipkema, P; Westerhof, N

1990-06-01

The autoregulating vascular bed of the isolated canine extensor digitorum longus muscle was investigated for the possible existence of two positive zero-flow pressure axis intercepts, a tone-dependent one and a tone-independent one. An isolated preparation, perfused with autologous blood, was used to exclude effects of collateral flow and nervous and humoral regulation while autoregulation was left intact [mean autoregulatory gain 0.50 +/- 0.24 (SD)]. In a first series of experiments, the steady-state (zero flow) pressure axis intercept [mean 8.9 +/- 2.6 (SD) mmHg, tone independent] and the instantaneous (zero flow) pressure axis intercept [mean 28.5 +/- 9.9 (SD) mmHg, tone dependent] were determined as a function of venous pressure (range: 0-45 mmHg) and were independent of venous pressure until the venous pressure exceeded their respective values. Beyond this point the relations between the venous pressure and the steady-state and instantaneous pressure axis intercept followed the line of identity. The findings agree with the predictions of the vascular waterfall model. In a second series it was shown by means of administration of vasoactive drugs that the instantaneous pressure axis intercept is tone dependent, whereas the steady-state pressure axis intercept is not. It is concluded that there is a (proximal) tone-dependent zero-flow pressure at the arteriolar level and a (distal) tone-independent zero-flow pressure at the venous level.

A spacecraft attitude and articulation control system design for the Comet Halley intercept mission

NASA Technical Reports Server (NTRS)

Key, R. W.

1981-01-01

An attitude and articulation control system design for the Comet Halley 1986 intercept mission is presented. A spacecraft dynamics model consisting of five hinge-connected rigid bodies is used to analyze the spacecraft attitude and articulation control system performance. Inertial and optical information are combined to generate scan platform pointing commands. The comprehensive spacecraft model has been developed into a digital computer simulation program, which provides performance characteristics and insight pertaining to the control and dynamics of a Halley Intercept spacecraft. It is shown that scan platform pointing error has a maximum value of 1.8 milliradians during the four minute closest approach interval. It is also shown that the jitter or scan platform pointing rate error would have a maximum value of 2.5 milliradians/second for the nominal 1000 km closest approach distance trajectory and associated environment model.

Statistical Power for a Simultaneous Test of Factorial and Predictive Invariance

ERIC Educational Resources Information Center

Olivera-Aguilar, Margarita; Millsap, Roger E.

2013-01-01

A common finding in studies of differential prediction across groups is that although regression slopes are the same or similar across groups, group differences exist in regression intercepts. Building on earlier work by Birnbaum (1979), Millsap (1998) presented an invariant factor model that would explain such intercept differences as arising due…

Expert Anticipatory Skill in Striking Sports: A Review and a Model

ERIC Educational Resources Information Center

Muller, Sean; Abernethy, Bruce

2012-01-01

Expert performers in striking sports can hit objects moving at high speed with incredible precision. Exceptionally well developed anticipation skills are necessary to cope with the severe constraints on interception. In this paper, we provide a review of the empirical evidence regarding expert interception in striking sports and propose a…

Multilevel structural equation models for assessing moderation within and across levels of analysis.

PubMed

Preacher, Kristopher J; Zhang, Zhen; Zyphur, Michael J

2016-06-01

Social scientists are increasingly interested in multilevel hypotheses, data, and statistical models as well as moderation or interactions among predictors. The result is a focus on hypotheses and tests of multilevel moderation within and across levels of analysis. Unfortunately, existing approaches to multilevel moderation have a variety of shortcomings, including conflated effects across levels of analysis and bias due to using observed cluster averages instead of latent variables (i.e., "random intercepts") to represent higher-level constructs. To overcome these problems and elucidate the nature of multilevel moderation effects, we introduce a multilevel structural equation modeling (MSEM) logic that clarifies the nature of the problems with existing practices and remedies them with latent variable interactions. This remedy uses random coefficients and/or latent moderated structural equations (LMS) for unbiased tests of multilevel moderation. We describe our approach and provide an example using the publicly available High School and Beyond data with Mplus syntax in Appendix. Our MSEM method eliminates problems of conflated multilevel effects and reduces bias in parameter estimates while offering a coherent framework for conceptualizing and testing multilevel moderation effects. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Bias and inference from misspecified mixed-effect models in stepped wedge trial analysis.

PubMed

Thompson, Jennifer A; Fielding, Katherine L; Davey, Calum; Aiken, Alexander M; Hargreaves, James R; Hayes, Richard J

2017-10-15

Many stepped wedge trials (SWTs) are analysed by using a mixed-effect model with a random intercept and fixed effects for the intervention and time periods (referred to here as the standard model). However, it is not known whether this model is robust to misspecification. We simulated SWTs with three groups of clusters and two time periods; one group received the intervention during the first period and two groups in the second period. We simulated period and intervention effects that were either common-to-all or varied-between clusters. Data were analysed with the standard model or with additional random effects for period effect or intervention effect. In a second simulation study, we explored the weight given to within-cluster comparisons by simulating a larger intervention effect in the group of the trial that experienced both the control and intervention conditions and applying the three analysis models described previously. Across 500 simulations, we computed bias and confidence interval coverage of the estimated intervention effect. We found up to 50% bias in intervention effect estimates when period or intervention effects varied between clusters and were treated as fixed effects in the analysis. All misspecified models showed undercoverage of 95% confidence intervals, particularly the standard model. A large weight was given to within-cluster comparisons in the standard model. In the SWTs simulated here, mixed-effect models were highly sensitive to departures from the model assumptions, which can be explained by the high dependence on within-cluster comparisons. Trialists should consider including a random effect for time period in their SWT analysis model. © 2017 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd. © 2017 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd.

Bias and inference from misspecified mixed‐effect models in stepped wedge trial analysis

PubMed Central

Fielding, Katherine L.; Davey, Calum; Aiken, Alexander M.; Hargreaves, James R.; Hayes, Richard J.

2017-01-01

Many stepped wedge trials (SWTs) are analysed by using a mixed‐effect model with a random intercept and fixed effects for the intervention and time periods (referred to here as the standard model). However, it is not known whether this model is robust to misspecification. We simulated SWTs with three groups of clusters and two time periods; one group received the intervention during the first period and two groups in the second period. We simulated period and intervention effects that were either common‐to‐all or varied‐between clusters. Data were analysed with the standard model or with additional random effects for period effect or intervention effect. In a second simulation study, we explored the weight given to within‐cluster comparisons by simulating a larger intervention effect in the group of the trial that experienced both the control and intervention conditions and applying the three analysis models described previously. Across 500 simulations, we computed bias and confidence interval coverage of the estimated intervention effect. We found up to 50% bias in intervention effect estimates when period or intervention effects varied between clusters and were treated as fixed effects in the analysis. All misspecified models showed undercoverage of 95% confidence intervals, particularly the standard model. A large weight was given to within‐cluster comparisons in the standard model. In the SWTs simulated here, mixed‐effect models were highly sensitive to departures from the model assumptions, which can be explained by the high dependence on within‐cluster comparisons. Trialists should consider including a random effect for time period in their SWT analysis model. © 2017 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd. PMID:28556355

Analysis of the ecological water diversion project in Wenzhou City

NASA Astrophysics Data System (ADS)

Xu, Haibo; Fu, Lei; Lin, Tong

2018-02-01

As a developed city in China, Wenzhou City has been suffered from bad water quality for years. In order to improve the river network water quality, an ecological water diversion project was designed and executed by the regional government. In this study, an investigation and analysis of the regional ecological water diversion project is made for the purpose of examining the water quality improvements. A numerical model is also established, different water diversion flow rates and sewer interception levels are considered during the simulation. Simulation results reveal that higher flow rate and sewer interception level will greatly improve the river network water quality in Wenzhou City. The importance of the flow rate and interception level has been proved and future work will be focused on increasing the flow rate and upgrading the sewer interception level.

Impact of a social-emotional and character development program on school-level indicators of academic achievement, absenteeism, and disciplinary outcomes: A matched-pair, cluster randomized, controlled trial.

PubMed

Snyder, Frank; Flay, Brian; Vuchinich, Samuel; Acock, Alan; Washburn, Isaac; Beets, Michael; Li, Kin-Kit

2010-01-01

This paper reports the effects of a comprehensive elementary school-based social-emotional and character education program on school-level achievement, absenteeism, and disciplinary outcomes utilizing a matched-pair, cluster randomized, controlled design. The Positive Action Hawai'i trial included 20 racially/ethnically diverse schools (mean enrollment = 544) and was conducted from the 2002-03 through the 2005-06 academic years. Using school-level archival data, analyses comparing change from baseline (2002) to one-year post trial (2007) revealed that intervention schools scored 9.8% better on the TerraNova (2 nd ed.) test for reading and 8.8% on math; 20.7% better in Hawai'i Content and Performance Standards scores for reading and 51.4% better in math; and that intervention schools reported 15.2% lower absenteeism and fewer suspensions (72.6%) and retentions (72.7%). Overall, effect sizes were moderate to large (range 0.5-1.1) for all of the examined outcomes. Sensitivity analyses using permutation models and random-intercept growth curve models substantiated results. The results provide evidence that a comprehensive school-based program, specifically developed to target student behavior and character, can positively influence school-level achievement, attendance, and disciplinary outcomes concurrently.

The importance of radiation for semiempirical water-use efficiency models

DOE PAGES

Boese, Sven; Jung, Martin; Carvalhais, Nuno; ...

2017-06-22

Water-use efficiency (WUE) is a fundamental property for the coupling of carbon and water cycles in plants and ecosystems. Existing model formulations predicting this variable differ in the type of response of WUE to the atmospheric vapor pressure deficit of water (VPD). We tested a representative WUE model on the ecosystem scale at 110 eddy covariance sites of the FLUXNET initiative by predicting evapotranspiration (ET) based on gross primary productivity (GPP) and VPD. We found that introducing an intercept term in the formulation increases model performance considerably, indicating that an additional factor needs to be considered. We demonstrate that thismore » intercept term varies seasonally and we subsequently associate it with radiation. Replacing the constant intercept term with a linear function of global radiation was found to further improve model predictions of ET. Our new semiempirical ecosystem WUE formulation indicates that, averaged over all sites, this radiation term accounts for up to half (39–47 %) of transpiration. These empirical findings challenge the current understanding of water-use efficiency on the ecosystem scale.« less

Modeling snow accumulation and ablation processes in forested environments

NASA Astrophysics Data System (ADS)

Andreadis, Konstantinos M.; Storck, Pascal; Lettenmaier, Dennis P.

2009-05-01

The effects of forest canopies on snow accumulation and ablation processes can be very important for the hydrology of midlatitude and high-latitude areas. A mass and energy balance model for snow accumulation and ablation processes in forested environments was developed utilizing extensive measurements of snow interception and release in a maritime mountainous site in Oregon. The model was evaluated using 2 years of weighing lysimeter data and was able to reproduce the snow water equivalent (SWE) evolution throughout winters both beneath the canopy and in the nearby clearing, with correlations to observations ranging from 0.81 to 0.99. Additionally, the model was evaluated using measurements from a Boreal Ecosystem-Atmosphere Study (BOREAS) field site in Canada to test the robustness of the canopy snow interception algorithm in a much different climate. Simulated SWE was relatively close to the observations for the forested sites, with discrepancies evident in some cases. Although the model formulation appeared robust for both types of climates, sensitivity to parameters such as snow roughness length and maximum interception capacity suggested the magnitude of improvements of SWE simulations that might be achieved by calibration.

Interception in three dimensions - An energy formulation

NASA Technical Reports Server (NTRS)

Rajan, N.; Ardema, M. D.

1983-01-01

The problem of minimum-time interception of a target flying in three dimensional space is analyzed with the interceptor aircraft modeled through energy-state approximation. A coordinate transformation that uncouples the interceptor's extremals from the target motion in an open-loop sense is introduced, and the necessary conditions for optimality and the optimal controls are derived. Example extremals are shown.

Evaluating the Effectiveness of an Antimicrobial Stewardship Program on Reducing the Incidence Rate of Healthcare-Associated Clostridium difficile Infection: A Non-Randomized, Stepped Wedge, Single-Site, Observational Study.

PubMed

DiDiodato, Giulio; McArthur, Leslie

2016-01-01

The incidence rate of healthcare-associated Clostridium difficile infection (HA-CDI) is estimated at 1 in 100 patients. Antibiotic exposure is the most consistently reported risk factor for HA-CDI. Strategies to reduce the risk of HA-CDI have focused on reducing antibiotic utilization. Prospective audit and feedback is a commonly used antimicrobial stewardship intervention (ASi). The impact of this ASi on risk of HA-CDI is equivocal. This study examines the effectiveness of a prospective audit and feedback ASi on reducing the risk of HA-CDI. Single-site, 339 bed community-hospital in Barrie, Ontario, Canada. Primary outcome is HA-CDI incidence rate. Daily prospective and audit ASi is the exposure variable. ASi implemented across 6 wards in a non-randomized, stepped wedge design. Criteria for ASi; any intravenous antibiotic use for ≥ 48 hrs, any oral fluoroquinolone or oral second generation cephalosporin use for ≥ 48 hrs, or any antimicrobial use for ≥ 5 days. HA-CDI cases and model covariates were aggregated by ward, year and month starting September 2008 and ending February 2016. Multi-level mixed effect negative binomial regression analysis was used to model the primary outcome, with intercept and slope coefficients for ward-level random effects estimated. Other covariates tested for inclusion in the final model were derived from previously published risk factors. Deviance residuals were used to assess the model's goodness-of-fit. The dataset included 486 observation periods, of which 350 were control periods and 136 were intervention periods. After accounting for all other model covariates, the estimated overall ASi incidence rate ratio (IRR) was 0.48 (95% 0.30, 0.79). The ASi effect was independent of antimicrobial utilization. The ASi did not seem to reduce the risk of Clostridium difficile infection on the surgery wards (IRR 0.87, 95% CI 0.45, 1.69) compared to the medicine wards (IRR 0.42, 95% CI 0.28, 0.63). The ward-level burden of Clostridium difficile as measured by the ward's previous month's total CDI cases (CDI Lag) and the ward's current month's community-associated CDI cases (CA-CDI) was significantly associated with an increased risk of HA-CDI, with the estimated CDI Lag IRR of 1.21 (95% 1.15, 1.28) and the estimated CA-CDI IRR of 1.10 (95% CI 1.01, 1.20). The ward-level random intercept and slope coefficients were not significant. The final model demonstrated good fit. In this study, a daily prospective audit and feedback ASi resulted in a significant reduction in the risk of HA-CDI on the medicine wards, however, this effect was independent of an overall reduction in antibiotic utilization. In addition, the ward-level burden of Clostridium difficile was shown to significantly increase the risk of HA-CDI, reinforcing the importance of the environment as a source of HA-CDI.

The Hispanic Americans Baseline Alcohol Survey (HABLAS):Predictive invariance of Demographic Characteristics on Attitudes towards Alcohol across Hispanic National Groups#

PubMed Central

Mills, Britain A.; Caetano, Raul; Bernstein, Ira H.

2011-01-01

This study compares the demographic predictors of items assessing attitudes towards drinking across Hispanic national groups. Data were from the 2006 Hispanic Americans Baseline Alcohol Survey (HABLAS), which used a multistage cluster sample design to interview 5,224 individuals randomly selected from the household population in Miami, New York, Philadelphia, Houston, and Los Angeles. Predictive invariance of demographic predictors of alcohol attitudes over four Hispanic national groups (Puerto Rican, Cuban, Mexican, and South/Central Americans) was examined using multiple-group seemingly unrelated probit regression. The analyses examined whether the influence of various demographic predictors varied across the Hispanic national groups in their regression coefficients, item intercepts, and error correlations. The hypothesis of predictive invariance was supported. Hispanic groups did not differ in how demographic predictors related to individual attitudinal items (regression slopes were invariant). In addition, the groups did not differ in attitudinal endorsement rates once demographic covariates were taken into account (item intercepts were invariant). Although Hispanic groups have different attitudes about alcohol, the influence of multiple demographic characteristics on alcohol attitudes operates similarly across Hispanic groups. Future models of drinking behavior in adult Hispanics need not posit moderating effects of group on the relation between these background characteristics and attitudes. PMID:25379120

Fast adaptation of the internal model of gravity for manual interceptions: evidence for event-dependent learning.

PubMed

Zago, Myrka; Bosco, Gianfranco; Maffei, Vincenzo; Iosa, Marco; Ivanenko, Yuri P; Lacquaniti, Francesco

2005-02-01

We studied how subjects learn to deal with two conflicting sensory environments as a function of the probability of each environment and the temporal distance between repeated events. Subjects were asked to intercept a visual target moving downward on a screen with randomized laws of motion. We compared five protocols that differed in the probability of constant speed (0g) targets and accelerated (1g) targets. Probability ranged from 9 to 100%, and the time interval between consecutive repetitions of the same target ranged from about 1 to 20 min. We found that subjects systematically timed their responses consistent with the assumption of gravity effects, for both 1 and 0g trials. With training, subjects rapidly adapted to 0g targets by shifting the time of motor activation. Surprisingly, the adaptation rate was independent of both the probability of 0g targets and their temporal distance. Very few 0g trials sporadically interspersed as catch trials during immersive practice with 1g trials were sufficient for learning and consolidation in long-term memory, as verified by retesting after 24 h. We argue that the memory store for adapted states of the internal gravity model is triggered by individual events and can be sustained for prolonged periods of time separating sporadic repetitions. This form of event-related learning could depend on multiple-stage memory, with exponential rise and decay in the initial stages followed by a sample-and-hold module.

Time series of canopy intercepted water and dew observed in a tropical tree plantation by means of microwave radiometry

NASA Astrophysics Data System (ADS)

Schneebeli, M.; Wolf, S.; Kunert, N.; Eugster, W.; Mätzler, C.

2012-04-01

During summer and autumn 2007, a 11 GHz microwave radiometer was deployed in an experimental tree plantation in Sardinilla, Panama. With this instrument, the opacity of the tree canopy was derived from incoming brightness temperatures received on the ground. A collocated eddy-covariance flux tower measured water vapor fluxes and meteorological variables above the canopy. It was found that canopy intercepted rain and dew formation modulated the diurnal opacity cycle. With an enhanced canopy opacity model accounting for water deposited on the leaves, we quantified the influence of canopy stored water (i.e. intercepted water and dew) on the opacity. With this technique it was possible to directly monitor high resolution time series of dew formation and rain interception during a period of two weeks. In contrast to through-fall measurements, this new technique allows to determine the amount of intercepted rain more precisely and during day and night since evaporation effects do not hamper the accuracy of the method. We found that during light rainfall up to 60% of the rain amount is intercepted by the canopy whereas during periods of intense rainfall, only 4% were intercepted. On average, about 15% of the rain amount was intercepted during rainfalls of medium intensities. By comparing the interception with the water vapor flux time series it was found that intercepted water is evaporated rapidly after it is deposited on the leaves, which resulted in an enhanced water vapor flux. Our study also provides the first direct measurements and quantifications of the temporal evolution of dew formation and evaporation in a tree canopy on a diurnal base. Dew accumulated during the night and until about 2 h after sunrise, when the water vapor flux began to exceed the dew formation rate. The dew continued to evaporate for another 3.5 h until the surface of the leaves was completely dry. On average, 0.17 mm of dew was formed during the night. Dew evaporation contributed 5% to the total water vapor flux measured above the canopy.

A novel guidance law using fast terminal sliding mode control with impact angle constraints.

PubMed

Sun, Lianghua; Wang, Weihong; Yi, Ran; Xiong, Shaofeng

2016-09-01

This paper is concerned with the question of, for a missile interception with impact angle constraints, how to design a guidance law. Firstly, missile interception with impact angle constraints is modeled; secondly, a novel guidance law using fast terminal sliding mode control based on extended state observer is proposed to optimize the trajectory and time of interception; finally, for stationary targets, constant velocity targets and maneuvering targets, the guidance law and the stability of the closed loop system is analyzed and the stability of the closed loop system is analyzed, respectively. Simulation results show that when missile and target are on a collision course, the novel guidance law using fast terminal sliding mode control with extended state observer has more optimized trajectory and effectively reduces the time of interception which has a great significance in modern warfare. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Evaluating interception of larval pallid sturgeon on the Lower Missouri River- data acquisition, interpolation, and visualization

NASA Astrophysics Data System (ADS)

Bulliner, E. A., IV; Erwin, S. O.; Anderson, B. J.; Wilson, H.; Jacobson, R. B.

2016-12-01

The transition from endogenous to exogenous feeding is an important life-stage transition for many riverine fish larvae. On the Missouri River, U.S., riverine alteration has decreased connectivity between the navigation channel and complex, food-producing and foraging areas on the channel margins, namely shallow side channels and sandbar complexes. A favored hypothesis, the interception hypothesis, for recruitment failure of pallid sturgeon is that drifting larvae are not able to exit the highly engineered navigation channel, and therefore starve. We present work exploring measures of hydraulic connectivity between the navigation channel and channel margins using multiple data-collection protocols with acoustic Doppler current profilers (ADCPs). As ADCP datasets alone often do not have high enough spatial resolution to characterize interception and connectivity sufficiently at the scale of drifting sturgeon larvae, they are often supplemented with physical and empirical models. Using boat-mounted ADCPs, we collected 3-dimensional current velocities with a variety of driving techniques (specifically, regularly spaced transects, reciprocal transects, and irregular patterns) around areas of potential larval interception. We then used toolkits based in Python to interpolate 3-dimensional velocity fields at spatial scales finer than the original measurements, and visualized resultant velocity vectors and flowlines in the software package Paraview. Using these visualizations, we investigated the necessary resolution of field measurements required to model connectivity with channel margin areas on large, highly engineered river ecosystems such as the Missouri River. We anticipate that results from this work will be used to help inform models of larval interception under current conditions. Furthermore, results from this work will be useful in developing monitoring strategies to evaluate the restoration of channel complexity to support ecological functions.

Rates and Implications of Rainfall Interception in a Coastal Redwood Forest

Treesearch

Leslie M. Reid; Jack Lewis

2007-01-01

Throughfall was measured for a year at five-min intervals in 11 collectors randomly located on two plots in a second-growth redwood forest at the Caspar Creek Experimental Watersheds. Monitoring at one plot continued two more years, during which stemflow from 24 trees was also measured. Comparison of throughfall and stemflow to rainfall measured in adjacent clearings...

Promoting motivation through mode of instruction: The relationship between use of affective teaching techniques and motivation to learn science

NASA Astrophysics Data System (ADS)

Sanchez Rivera, Yamil

The purpose of this study is to add to what we know about the affective domain and to create a valid instrument for future studies. The Motivation to Learn Science (MLS) Inventory is based on Krathwohl's Taxonomy of Affective Behaviors (Krathwohl et al., 1964). The results of the Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) demonstrated that the MLS Inventory is a valid and reliable instrument. Therefore, the MLS Inventory is a uni-dimensional instrument composed of 9 items with convergent validity (no divergence). The instrument had a high Chronbach Alpha value of .898 during the EFA analysis and .919 with the CFA analysis. Factor loadings on the 9 items ranged from .617 to .800. Standardized regression weights ranged from .639 to .835 in the CFA analysis. Various indices (RMSEA = .033; NFI = .987; GFI = .985; CFI = 1.000) demonstrated a good fitness of the proposed model. Hierarchical linear modeling was used to statistical analyze data where students' motivation to learn science scores (level-1) were nested within teachers (level-2). The analysis was geared toward identifying if teachers' use of affective behavior (a level-2 classroom variable) was significantly related with students' MLS scores (level-1 criterion variable). Model testing proceeded in three phases: intercept-only model, means-as-outcome model, and a random-regression coefficient model. The intercept-only model revealed an intra-class correlation coefficient of .224 with an estimated reliability of .726. Therefore, data suggested that only 22.4% of the variance in MLS scores is between-classes and the remaining 77.6% is at the student-level. Due to the significant variance in MLS scores, X2(62.756, p<.0001), teachers' TAB scores were added as a level-2 predictor. The regression coefficient was non-significant (p>.05). Therefore, the teachers' self-reported use of affective behaviors was not a significant predictor of students' motivation to learn science.

Optimal Deployment of Unmanned Aerial Vehicles for Border Surveillance

DTIC Science & Technology

2014-06-01

and intercept intruders that are trying to trespass a border. These intruders can include terrorists, drug traffickers, smugglers, illegal immigrants...routes, altitudes, and speeds in order to maximize the probability of detecting intruders trying to trespass a given border. These models will...Border surveillance is an important concern for most nations wanting to detect and intercept intruders that are trying to trespass a border. These

When up is down in 0g: how gravity sensing affects the timing of interceptive actions.

PubMed

Senot, Patrice; Zago, Myrka; Le Séac'h, Anne; Zaoui, Mohammed; Berthoz, Alain; Lacquaniti, Francesco; McIntyre, Joseph

2012-02-08

Humans are known to regulate the timing of interceptive actions by modeling, in a simplified way, Newtonian mechanics. Specifically, when intercepting an approaching ball, humans trigger their movements a bit earlier when the target arrives from above than from below. This bias occurs regardless of the ball's true kinetics, and thus appears to reflect an a priori expectation that a downward moving object will accelerate. We postulate that gravito-inertial information is used to tune visuomotor responses to match the target's most likely acceleration. Here we used the peculiar conditions of parabolic flight--where gravity's effects change every 20 s--to test this hypothesis. We found a striking reversal in the timing of interceptive responses performed in weightlessness compared with trials performed on ground, indicating a role of gravity sensing in the tuning of this response. Parallels between these observations and the properties of otolith receptors suggest that vestibular signals themselves might plausibly provide the critical input. Thus, in addition to its acknowledged importance for postural control, gaze stabilization, and spatial navigation, we propose that detecting the direction of gravity's pull plays a role in coordinating quick reactions intended to intercept a fast-moving visual target.

Role Stress and Emotional Exhaustion Among Health Care Workers: The Buffering Effect of Supportive Coworker Climate in a Multilevel Perspective.

PubMed

Portoghese, Igor; Galletta, Maura; Burdorf, Alex; Cocco, Pierluigi; D'Aloja, Ernesto; Campagna, Marcello

2017-10-01

The aim of the study was to examine the relationship between role stress, emotional exhaustion, and a supportive coworker climate among health care workers, by adopting a multilevel perspective. Aggregated data of 738 health care workers nested within 67 teams of three Italian hospitals were collected. Multilevel regression analysis with a random intercept model was used. Hierarchical linear modeling showed that a lack of role clarity was significantly linked to emotional exhaustion at the individual level. At the unit level, the cross-level interaction revealed that a supportive coworker climate moderated the relationship between lack of role clarity and emotional exhaustion. This study supports previous results of single-level burnout studies, extending the existing literature with evidence on the multidimensional and cross-level interaction associations of a supportive coworker climate as a key aspect of job resources on burnout.

In vivo growth of 60 non-screening detected lung cancers: a computed tomography study.

PubMed

Mets, Onno M; Chung, Kaman; Zanen, Pieter; Scholten, Ernst T; Veldhuis, Wouter B; van Ginneken, Bram; Prokop, Mathias; Schaefer-Prokop, Cornelia M; de Jong, Pim A

2018-04-01

Current pulmonary nodule management guidelines are based on nodule volume doubling time, which assumes exponential growth behaviour. However, this is a theory that has never been validated in vivo in the routine-care target population. This study evaluates growth patterns of untreated solid and subsolid lung cancers of various histologies in a non-screening setting.Growth behaviour of pathology-proven lung cancers from two academic centres that were imaged at least three times before diagnosis (n=60) was analysed using dedicated software. Random-intercept random-slope mixed-models analysis was applied to test which growth pattern most accurately described lung cancer growth. Individual growth curves were plotted per pathology subgroup and nodule type.We confirmed that growth in both subsolid and solid lung cancers is best explained by an exponential model. However, subsolid lesions generally progress slower than solid ones. Baseline lesion volume was not related to growth, indicating that smaller lesions do not grow slower compared to larger ones.By showing that lung cancer conforms to exponential growth we provide the first experimental basis in the routine-care setting for the assumption made in volume doubling time analysis. Copyright ©ERS 2018.

Physical-layer security analysis of a quantum-noise randomized cipher based on the wire-tap channel model.

PubMed

Jiao, Haisong; Pu, Tao; Zheng, Jilin; Xiang, Peng; Fang, Tao

2017-05-15

The physical-layer security of a quantum-noise randomized cipher (QNRC) system is, for the first time, quantitatively evaluated with secrecy capacity employed as the performance metric. Considering quantum noise as a channel advantage for legitimate parties over eavesdroppers, the specific wire-tap models for both channels of the key and data are built with channel outputs yielded by quantum heterodyne measurement; the general expressions of secrecy capacities for both channels are derived, where the matching codes are proved to be uniformly distributed. The maximal achievable secrecy rate of the system is proposed, under which secrecy of both the key and data is guaranteed. The influences of various system parameters on secrecy capacities are assessed in detail. The results indicate that QNRC combined with proper channel codes is a promising framework of secure communication for long distance with high speed, which can be orders of magnitude higher than the perfect secrecy rates of other encryption systems. Even if the eavesdropper intercepts more signal power than the legitimate receiver, secure communication (up to Gb/s) can still be achievable. Moreover, the secrecy of running key is found to be the main constraint to the systemic maximal secrecy rate.

Genome-wide association study on legendre random regression coefficients for the growth and feed intake trajectory on Duroc Boars.

PubMed

Howard, Jeremy T; Jiao, Shihui; Tiezzi, Francesco; Huang, Yijian; Gray, Kent A; Maltecca, Christian

2015-05-30

Feed intake and growth are economically important traits in swine production. Previous genome wide association studies (GWAS) have utilized average daily gain or daily feed intake to identify regions that impact growth and feed intake across time. The use of longitudinal models in GWAS studies, such as random regression, allows for SNPs having a heterogeneous effect across the trajectory to be characterized. The objective of this study is therefore to conduct a single step GWAS (ssGWAS) on the animal polynomial coefficients for feed intake and growth. Corrected daily feed intake (DFI Adj) and average daily weight measurements (DBW Avg) on 8981 (n=525,240 observations) and 5643 (n=283,607 observations) animals were utilized in a random regression model using Legendre polynomials (order=2) and a relationship matrix that included genotyped and un-genotyped animals. A ssGWAS was conducted on the animal polynomials coefficients (intercept, linear and quadratic) for animals with genotypes (DFIAdj: n=855; DBWAvg: n=590). Regions were characterized based on the variance of 10-SNP sliding windows GEBV (WGEBV). A bootstrap analysis (n=1000) was conducted to declare significance. Heritability estimates for the traits trajectory ranged from 0.34-0.52 to 0.07-0.23 for DBWAvg and DFIAdj, respectively. Genetic correlations across age classes were large and positive for both DBWAvg and DFIAdj, albeit age classes at the beginning had a small to moderate genetic correlation with age classes towards the end of the trajectory for both traits. The WGEBV variance explained by significant regions (P<0.001) for each polynomial coefficient ranged from 0.2-0.9 to 0.3-1.01% for DBWAvg and DFIAdj, respectively. The WGEBV variance explained by significant regions for the trajectory was 1.54 and 1.95% for DBWAvg and DFIAdj. Both traits identified candidate genes with functions related to metabolite and energy homeostasis, glucose and insulin signaling and behavior. We have identified regions of the genome that have an impact on the intercept, linear and quadratic terms for DBWAvg and DFIAdj. These results provide preliminary evidence that individual growth and feed intake trajectories are impacted by different regions of the genome at different times.

Modelling subject-specific childhood growth using linear mixed-effect models with cubic regression splines.

PubMed

Grajeda, Laura M; Ivanescu, Andrada; Saito, Mayuko; Crainiceanu, Ciprian; Jaganath, Devan; Gilman, Robert H; Crabtree, Jean E; Kelleher, Dermott; Cabrera, Lilia; Cama, Vitaliano; Checkley, William

2016-01-01

Childhood growth is a cornerstone of pediatric research. Statistical models need to consider individual trajectories to adequately describe growth outcomes. Specifically, well-defined longitudinal models are essential to characterize both population and subject-specific growth. Linear mixed-effect models with cubic regression splines can account for the nonlinearity of growth curves and provide reasonable estimators of population and subject-specific growth, velocity and acceleration. We provide a stepwise approach that builds from simple to complex models, and account for the intrinsic complexity of the data. We start with standard cubic splines regression models and build up to a model that includes subject-specific random intercepts and slopes and residual autocorrelation. We then compared cubic regression splines vis-à-vis linear piecewise splines, and with varying number of knots and positions. Statistical code is provided to ensure reproducibility and improve dissemination of methods. Models are applied to longitudinal height measurements in a cohort of 215 Peruvian children followed from birth until their fourth year of life. Unexplained variability, as measured by the variance of the regression model, was reduced from 7.34 when using ordinary least squares to 0.81 (p < 0.001) when using a linear mixed-effect models with random slopes and a first order continuous autoregressive error term. There was substantial heterogeneity in both the intercept (p < 0.001) and slopes (p < 0.001) of the individual growth trajectories. We also identified important serial correlation within the structure of the data (ρ = 0.66; 95 % CI 0.64 to 0.68; p < 0.001), which we modeled with a first order continuous autoregressive error term as evidenced by the variogram of the residuals and by a lack of association among residuals. The final model provides a parametric linear regression equation for both estimation and prediction of population- and individual-level growth in height. We show that cubic regression splines are superior to linear regression splines for the case of a small number of knots in both estimation and prediction with the full linear mixed effect model (AIC 19,352 vs. 19,598, respectively). While the regression parameters are more complex to interpret in the former, we argue that inference for any problem depends more on the estimated curve or differences in curves rather than the coefficients. Moreover, use of cubic regression splines provides biological meaningful growth velocity and acceleration curves despite increased complexity in coefficient interpretation. Through this stepwise approach, we provide a set of tools to model longitudinal childhood data for non-statisticians using linear mixed-effect models.

Resolvin D1 prevents smoking-induced emphysema and promotes lung tissue regeneration.

PubMed

Kim, Kang-Hyun; Park, Tai Sun; Kim, You-Sun; Lee, Jae Seung; Oh, Yeon-Mok; Lee, Sang-Do; Lee, Sei Won

2016-01-01

Emphysema is an irreversible disease that is characterized by destruction of lung tissue as a result of inflammation caused by smoking. Resolvin D1 (RvD1), derived from docosahexaenoic acid, is a novel lipid that resolves inflammation. The present study tested whether RvD1 prevents smoking-induced emphysema and promotes lung tissue regeneration. C57BL/6 mice, 8 weeks of age, were randomly divided into four groups: control, RvD1 only, smoking only, and smoking with RvD1 administration. Four different protocols were used to induce emphysema and administer RvD1: mice were exposed to smoking for 4 weeks with poly(I:C) or to smoking only for 24 weeks, and RvD1 was injected within the smoking exposure period to prevent regeneration or after completion of smoking exposure to assess regeneration. The mean linear intercept and inflammation scores were measured in the lung tissue, and inflammatory cells and cytokines were measured in the bronchoalveolar lavage fluid. Measurements of mean linear intercept showed that RvD1 significantly attenuated smoking-induced lung destruction in all emphysema models. RvD1 also reduced smoking-induced inflammatory cell infiltration, which causes the structural derangements observed in emphysema. In the 4-week prevention model, RvD1 reduced the smoking-induced increase in eosinophils and interleukin-6 in the bronchoalveolar lavage fluid. In the 24-week prevention model, RvD1 also reduced the increased neutrophils and total cell counts induced by smoking. RvD1 attenuated smoking-induced emphysema in vivo by reducing inflammation and promoting tissue regeneration. This result suggests that RvD1 may be useful in the prevention and treatment of emphysema.

Quantifying interception associated with new urban vegetation canopies

NASA Astrophysics Data System (ADS)

Yerk, W.; Montalto, F. A.

2013-12-01

Interception of precipitation by vegetation canopies has long been recognized as an important component of the hydrologic cycle, though most research has been in closed or sparse canopy forests. Much less work has been published on interception by urban vegetation, and especially associated with the low growing shrubs commonly installed in green infrastructure program. To inform urban watershed model with vegetation-specific interception data, a field experiment was designed to directly measure canopy throughfall associated with two shrub species commonly included in urban greening programs. Data was collected at a high (e.g. five second) sampling frequency. A non-parametric Kruskal-Wallis test performed on data collected between August and October of 2012 demonstrated statistically significant (p= 0.0011) differences in recorded throughfall between two species (94% for Itea virginica, 86% for Cornus sericea). Additionally, the results suggested that the relationship of throughfall to rainfall intensity varied by species. For Itea, the ratio of throughfall to precipitation intensity was close to 1:1. However, for Cornus, the throughfall rate was on average slower (or 0.85 of the precipitation intensity). An improved and expanded set-up installed in 2013 added two additional species (Prunus laurocerasus and Hydrangea quercifolia). The 2013 results confirm interspecies differences in both throughfall amount, and in the relationship of throughfall rate to precipitation intensity. The results are discussed with respect to droplet splashing and enhanced evaporation within the canopy. Both years' findings suggest that the quantity of water intercepted by vegetation canopies exceeds the canopy storage capacity, as assumed in many conventional hydrologic models.

Measurement of snow interception and canopy effects on snow accumulation and melt in a mountainous maritime climate, Oregon, United States

NASA Astrophysics Data System (ADS)

Storck, Pascal; Lettenmaier, Dennis P.; Bolton, Susan M.

2002-11-01

The results of a 3 year field study to observe the processes controlling snow interception by forest canopies and under canopy snow accumulation and ablation in mountain maritime climates are reported. The field study was further intended to provide data to develop and test models of forest canopy effects on beneath-canopy snowpack accumulation and melt and the plot and stand scales. Weighing lysimeters, cut-tree experiments, and manual snow surveys were deployed at a site in the Umpqua National Forest, Oregon (elevation 1200 m). A unique design for a weighing lysimeter was employed that allowed continuous measurements of snowpack evolution beneath a forest canopy to be taken at a scale unaffected by variability in canopy throughfall. Continuous observations of snowpack evolution in large clearings were made coincidentally with the canopy measurements. Large differences in snow accumulation and ablation were observed at sites beneath the forest canopy and in large clearings. These differences were not well described by simple relationships between the sites. Over the study period, approximately 60% of snowfall was intercepted by the canopy (up to a maximum of about 40 mm water equivalent). Instantaneous sublimation rates exceeded 0.5 mm per hour for short periods. However, apparent average sublimation from the intercepted snow was less than 1 mm per day and totaled approximately 100 mm per winter season. Approximately 72 and 28% of the remaining intercepted snow was removed as meltwater drip and large snow masses, respectively. Observed differences in snow interception rate and maximum snow interception capacity between Douglas fir (Pseudotsuga menziesii), white fir (Abies concolor), ponderosa pine (Pinus ponderosa), and lodgepole pine (Pinus contorta) were minimal.

Unitary Suprathreshold Color-Difference Metrics of Legibility for CRT Raster Imagery.

DTIC Science & Technology

1986-09-01

observers possessing norma vision could accurately read random numeral strings of one color displayed DD J 4-73 EDITION OF C 6S IS OBSOLETE - SEURT CLSIICTO...34 Table 2, continued. SAE (L*,u*,v*) : .909 .940 Intercept 1. 8581 1. 8022 " N -0. 3980 -0.3655 m .AE 0. 1217 0. 1206-" =, E -0. 0019 -0. 0017 * all t > 3

Modelling rainfall interception by a lowland tropical rain forest in northeastern Puerto Rico

Treesearch

J. Schellekensa; F.N. Scatenab; L.A. Bruijnzeela; A.J. \\t Wickela

1999-01-01

Recent surveys of tropical forest water use suggest that rainfall interception by the canopy is largest in wet maritime locations. To investigate the underlying processes at one such location—the Luquillo Experimental Forest in eastern Puerto Rico—66 days of detailed throughfall and above-canopy climatic data were collected in 1996 and analysed using the Rutter and...

Multilevel poisson regression modelling for determining factors of dengue fever cases in bandung

NASA Astrophysics Data System (ADS)

Arundina, Davila Rubianti; Tantular, Bertho; Pontoh, Resa Septiani

2017-03-01

Scralatina or Dengue Fever is a kind of fever caused by serotype virus which Flavivirus genus and be known as Dengue Virus. Dengue Fever caused by Aedes Aegipty Mosquito bites who infected by a dengue virus. The study was conducted in 151 villages in Bandung. Health Analysts believes that there are two factors that affect the dengue cases, Internal factor (individual) and external factor (environment). The data who used in this research is hierarchical data. The method is used for hierarchical data modelling is multilevel method. Which is, the level 1 is village and level 2 is sub-district. According exploration data analysis, the suitable Multilevel Method is Random Intercept Model. Penalized Quasi Likelihood (PQL) approach on multilevel Poisson is a proper analysis to determine factors that affecting dengue cases in the city of Bandung. Clean and Healthy Behavior factor from the village level have an effect on the number of cases of dengue fever in the city of Bandung. Factor from the sub-district level has no effect.

Growth of finiteness in the third year of life: replication and predictive validity.

PubMed

Hadley, Pamela A; Rispoli, Matthew; Holt, Janet K; Fitzgerald, Colleen; Bahnsen, Alison

2014-06-01

The authors of this study investigated the validity of tense and agreement productivity (TAP) scoring in diverse sentence frames obtained during conversational language sampling as an alternative measure of finiteness for use with young children. Longitudinal language samples were used to model TAP growth from 21 to 30 months of age for 37 typically developing toddlers. Empirical Bayes (EB) linear and quadratic growth coefficients and child sex were then used to predict elicited grammar composite scores on the Test of Early Grammatical Impairment (TEGI; Rice & Wexler, 2001) at 36 months. A random-effects quadratic model with no intercept best characterized TAP growth, replicating the findings of Rispoli, Hadley, and Holt (2009). The combined regression model was significant, with the 3 variables accounting for 55.5% of the variance in the TEGI composite scores. These findings establish TAP growth as a valid metric of finiteness in the 3rd year of life. Developmental and theoretical implications are discussed.

Ultrasonic RF time series for early assessment of the tumor response to chemotherapy.

PubMed

Lin, Qingguang; Wang, Jianwei; Li, Qing; Lin, Chunyi; Guo, Zhixing; Zheng, Wei; Yan, Cuiju; Li, Anhua; Zhou, Jianhua

2018-01-05

Ultrasound radio-frequency (RF) time series have been shown to carry tissue typing information. To evaluate the potential of RF time series for early prediction of tumor response to chemotherapy, 50MCF-7 breast cancer-bearing nude mice were randomized to receive cisplatin and paclitaxel (treatment group; n = 26) or sterile saline (control group; n = 24). Sequential ultrasound imaging was performed on days 0, 3, 6, and 8 of treatment to simultaneously collect B-mode images and RF data. Six RF time series features, slope, intercept, S1, S2, S3 , and S4 , were extracted during RF data analysis and contrasted with microstructural tumor changes on histopathology. Chemotherapy administration reduced tumor growth relative to control on days 6 and 8. Compared with day 0, intercept, S1 , and S2 were increased while slope was decreased on days 3, 6, and 8 in the treatment group. Compared with the control group, intercept, S1, S2, S3 , and S4 were increased, and slope was decreased, on days 3, 6, and 8 in the treatment group. Tumor cell density decreased significantly in the latter on day 3. We conclude that ultrasonic RF time series analysis provides a simple way to noninvasively assess the early tumor response to chemotherapy.

Action-perception dissociation in response to target acceleration.

PubMed

Dubrowski, Adam; Carnahan, Heather

2002-05-01

The purpose of this study was to investigate whether information about the acceleration characteristics of a moving target can be used for both action and perception. Also of interest was whether prior movement experience altered perceptual judgements. Participants manually intercepted targets moving with various acceleration, velocity and movement time characteristics. They also made perceptual judgements about the acceleration characteristics of these targets either with or without prior manual interception experience. Results showed that while aiming kinematics were sensitive to the acceleration characteristics of the target, participants were only able to perceptually discriminate the velocity characteristics of target motion, even after performing interceptive actions to the same targets. These results are discussed in terms of a two channel (action-perception) model of visuomotor control.

The pattern of the discovery of medication errors in a tertiary hospital in Hong Kong.

PubMed

Samaranayake, N R; Cheung, S T D; Chui, W C M; Cheung, B M Y

2013-06-01

The primary goal of reducing medication errors is to eliminate those that reach the patient. We aimed to study the pattern of interceptions to tackle medication errors along the medication use processes. Tertiary care hospital in Hong Kong. The 'Swiss Cheese Model' was used to explain the interceptions targeting medication error reporting over 5 years (2006-2010). Proportions of prescribing, dispensing and drug administration errors intercepted by pharmacists and nurses; proportions of prescribing, dispensing and drug administration errors that reached the patient. Our analysis included 1,268 in-patient medication errors, of which 53.4% were related to prescribing, 29.0% to administration and 17.6% to dispensing. 34.1% of all medication errors (4.9% prescribing, 26.8% drug administration and 2.4% dispensing) were not intercepted. Pharmacy staff intercepted 85.4% of the prescribing errors. Nurses detected 83.0% of dispensing and 5.0% of prescribing errors. However, 92.4% of all drug administration errors reached the patient. Having a preventive measure at each stage of the medication use process helps to prevent most errors. Most drug administration errors reach the patient as there is no defense against these. Therefore, more interventions to prevent drug administration errors are warranted.

The perceptual control of goal-directed locomotion: a common control architecture for interception and navigation?

PubMed

Chardenon, A; Montagne, G; Laurent, M; Bootsma, R J

2004-09-01

Intercepting a moving object while locomoting is a highly complex and demanding ability. Notwithstanding the identification of several informational candidates, the role of perceptual variables in the control process underlying such skills remains an open question. In this study we used a virtual reality set-up for studying locomotor interception of a moving ball. The subject had to walk along a straight path and could freely modify forward velocity, if necessary, in order to intercept-with the head-a ball moving along a straight path that led it to cross the agent's displacement axis. In a series of experiments we manipulated a local (ball size) and a global (focus of expansion) component of the visual flow but also the egocentric orientation of the ball. The experimental observations are well captured by a dynamic model linking the locomotor acceleration to properties of both global flow and egocentric direction. More precisely the changes in locomotor velocity depend on a linear combination of the change in bearing angle and the change in egocentric orientation, allowing the emergence of adaptive behavior under a variety of circumstances. We conclude that the mechanisms underlying the control of different goal-directed locomotion tasks (i.e. steering and interceptive tasks) could share a common architecture.

New Hypervelocity Terminal Intercept Guidance Systems for Deflecting/Disrupting Hazardous Asteroids

NASA Astrophysics Data System (ADS)

Lyzhoft, Joshua Richard

Computational modeling and simulations of visual and infrared (IR) sensors are investigated for a new hypervelocity terminal guidance system of intercepting small asteroids (50 to 150 meters in diameter). Computational software tools for signal-to-noise ratio estimation of visual and IR sensors, estimation of minimum and maximum ranges of target detection, and GPU (Graphics Processing Units)-accelerated simulations of the IR-based terminal intercept guidance systems are developed. Scaled polyhedron models of known objects, such as the Rosetta mission's Comet 67P/C-G, NASA's OSIRIS-REx Bennu, and asteroid 433 Eros, are utilized in developing a GPU-based simulation tool for the IR-based terminal intercept guidance systems. A parallelized-ray tracing algorithm for simulating realistic surface-to-surface shadowing of irregular-shaped asteroids or comets is developed. Polyhedron solid-angle approximation is also considered. Using these computational models, digital image processing is investigated to determine single or multiple impact locations to assess the technical feasibility of new planetary defense mission concepts of utilizing a Hypervelocity Asteroid Intercept Vehicle (HAIV) or a Multiple Kinetic-energy Interceptor Vehicle (MKIV). Study results indicate that the IR-based guidance system outperforms the visual-based system in asteroid detection and tracking. When using an IR sensor, predicting impact locations from filtered images resulted in less jittery spacecraft control accelerations than conducting missions with a visual sensor. Infrared sensors have also the possibility to detect asteroids at greater distances, and if properly used, can aid in terminal phase guidance for proper impact location determination for the MKIV system. Emerging new topics of the Minimum Orbit Intersection Distance (MOID) estimation and the Full-Two-Body Problem (F2BP) formulation are also investigated to assess a potential near-Earth object collision risk and the proximity gravity effects of an irregular-shaped binary-asteroid target on a standoff nuclear explosion mission.

Missile Guidance Law Based on Robust Model Predictive Control Using Neural-Network Optimization.

PubMed

Li, Zhijun; Xia, Yuanqing; Su, Chun-Yi; Deng, Jun; Fu, Jun; He, Wei

2015-08-01

In this brief, the utilization of robust model-based predictive control is investigated for the problem of missile interception. Treating the target acceleration as a bounded disturbance, novel guidance law using model predictive control is developed by incorporating missile inside constraints. The combined model predictive approach could be transformed as a constrained quadratic programming (QP) problem, which may be solved using a linear variational inequality-based primal-dual neural network over a finite receding horizon. Online solutions to multiple parametric QP problems are used so that constrained optimal control decisions can be made in real time. Simulation studies are conducted to illustrate the effectiveness and performance of the proposed guidance control law for missile interception.

Comparison of the evapotranspiration and its components before and after thinning in Japanese cedar and Japanese cypress forest

NASA Astrophysics Data System (ADS)

Tateishi, Makiko; Xiang, Yang; Matsuda, Hiroki; Saito, Takami; Sun, Haotian; Otsuki, Kyoichi; Kasahara, Tamao; Onda, Yuichi

2014-05-01

Water source area of Japan is often covered by forest, and 40 % of forest cover is coniferous plantation. Thinning has become a major tool in the management of plantation in recent years, but its effects on water cycle and its components are yet to be evaluated well. In this study, we investigated the changes in evapotranspiration and its components, including stand transpiration and canopy interception loss, after thinning in 50 years old Japanese cedar and Japanese cypress plantation at Yayama experimental catchment in Fukuoka, Japan. We established study plot in each Japanese cedar and Japanese cypress stand. Sap flow measurement was conducted for evaluating stand transpiration in each plot. Through fall and stem flow were also monitored to estimate canopy interception loss. The experiments were conducted over two years. During the measurements, 50 % of trees were thinned randomly in entire catchment, which has an area of 2.98 ha. Stem density was changed from 3945 to 1977 trees per ha after thinning. The reduction of daily stand transpiration in the studied Japanese cedar and cypress stands after thinning were 31.6 % and 48.2 % under the same condition of microclimate, respectively. These values were comparable to the changes in total sapwood area, 34.2 % and 44.5 %, and sap flow density did not change after thinning. It implies that sapwood area is a primary determinant of stand transpiration. Canopy interception ratios were 27 % and 26 % for Japanese cedar and cypress before thinning, and the ratios decreased to 24 % and 21 % after thinning, respectively. Thus, we obtained the changes in annual evapotranspiration and its components at catchment scale by using observation and models. The changes in partitioning of evapotranspiration is also discussed. The evapotranspiration before and after thinning were also compared to water balance data in this study site.

Expert anticipatory skill in striking sports: a review and a model.

PubMed

Müller, Sean; Abernethy, Bruce

2012-06-01

Expert performers in striking sports can hit objects moving at high speed with incredible precision. Exceptionally well developed anticipation skills are necessary to cope with the severe constraints on interception. In this papr we provide a review of the empirical evidence regarding expert interception in striking sports and propose a preliminary model of expert anticipation. Central to the review and the model is the notion that the visual information used to guide the sequential phases of the striking action is systematically different between experts and nonexperts. Knowing the factors that contribute to expert anticipation, and how anticipation may guide skilled performance in striking sports, has practical implications for assessment and training across skill levels.

Optimal Interception of a Maneuvering Long-range Missile

NASA Astrophysics Data System (ADS)

X. Vinh, Nguyen; T. Kabamba, Pierre; Takehira, Tetsuya

2001-01-01

In a Newtonian central force field, the minimum-fuel interception of a satellite, or a ballistic missile, in elliptic trajectory can be obtained via Lawden's theory of primer vector. To secure interception when the target performs evasive maneuvers, a new control law, with explicit solutions, is implemented. It is shown that by a rotation of coordinate system, the problem of three-dimensional interception is reduced to a planar problem. The general case of planar interception of a long-range ballistic missile is then studied. Examples of interception at a specified time, head-on interception and minimum-fuel interception are presented. In each case, the requirement for the thrust acceleration is expressed explicitly as a function of time.

The evolution of trade-offs: testing predictions on response to selection and environmental variation.

PubMed

Roff, Derek A; Mostowy, Serge; Fairbairn, Daphne J

2002-01-01

The concept of phenotypic trade-offs is a central element in evolutionary theory. In general, phenotypic models assume a fixed trade-off function, whereas quantitative genetic theory predicts that the trade-off function will change as a result of selection. For a linear trade-off function selection will readily change the intercept but will have to be relatively stronger to change the slope. We test these predictions by examining the trade-off between fecundity and flight capability, as measured by dorso-longitudinal muscle mass, in four different populations of the sand cricket, Gryllus firmus. Three populations were recently derived from the wild, and the fourth had been in the laboratory for 19 years. We hypothesized that the laboratory population had most likely undergone more and different selection from the three wild populations and therefore should differ from these in respect to both slope and intercept. Because of geographic variation in selection, we predicted a general difference in intercept among the four populations. We further tested the hypothesis that this intercept will be correlated with proportion macropterous and that this relationship will itself vary with environmental conditions experienced during both the nymphal and adult period. Observed variation in the phenotypic trade-off was consistent with the predictions of the quantitative genetic model. These results point to the importance of modeling trade-offs as dynamic rather than static relationships. We discuss how phenotypic models can incorporate such variation. The phenotypic trade-off between fecundity and dorso-longitudinal muscle mass is determined in part by variation in body size, illustrating the necessity of considering trade-offs to be multi factorial rather than simply bivariate relationships.

Dynamic prediction in functional concurrent regression with an application to child growth.

PubMed

Leroux, Andrew; Xiao, Luo; Crainiceanu, Ciprian; Checkley, William

2018-04-15

In many studies, it is of interest to predict the future trajectory of subjects based on their historical data, referred to as dynamic prediction. Mixed effects models have traditionally been used for dynamic prediction. However, the commonly used random intercept and slope model is often not sufficiently flexible for modeling subject-specific trajectories. In addition, there may be useful exposures/predictors of interest that are measured concurrently with the outcome, complicating dynamic prediction. To address these problems, we propose a dynamic functional concurrent regression model to handle the case where both the functional response and the functional predictors are irregularly measured. Currently, such a model cannot be fit by existing software. We apply the model to dynamically predict children's length conditional on prior length, weight, and baseline covariates. Inference on model parameters and subject-specific trajectories is conducted using the mixed effects representation of the proposed model. An extensive simulation study shows that the dynamic functional regression model provides more accurate estimation and inference than existing methods. Methods are supported by fast, flexible, open source software that uses heavily tested smoothing techniques. © 2017 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.

15 CFR 742.13 - Communications intercepting devices; software and technology for communications intercepting...

Code of Federal Regulations, 2013 CFR

2013-01-01

...; software and technology for communications intercepting devices. 742.13 Section 742.13 Commerce and Foreign... Communications intercepting devices; software and technology for communications intercepting devices. (a) License... wire, oral, or electronic communications (ECCNs 5A001.i and 5A980); and for related “software...

Designing dual-plate meteoroid shields: A new analysis

NASA Technical Reports Server (NTRS)

Swift, H. F.; Bamford, R.; Chen, R.

1982-01-01

Physics governing ultrahigh velocity impacts onto dual-plate meteor armor is discussed. Meteoroid shield design methodologies are considered: failure mechanisms, qualitative features of effective meteoroid shield designs, evaluating/processing meteoroid threat models, and quantitative techniques for optimizing effective meteoroid shield designs. Related investigations are included: use of Kevlar cloth/epoxy panels in meteoroid shields for the Halley's Comet intercept vehicle, mirror exposure dynamics, and evaluation of ion fields produced around the Halley Intercept Mission vehicle by meteoroid impacts.

What affects response rates in primary healthcare-based programmes? An analysis of individual and unit-related factors associated with increased odds of non-response based on HCV screening in the general population in Poland

PubMed Central

Parda, Natalia; Stępień, Małgorzata; Zakrzewska, Karolina; Madaliński, Kazimierz; Kołakowska, Agnieszka; Godzik, Paulina; Rosińska, Magdalena

2016-01-01

Objectives Response rate in public health programmes may be a limiting factor. It is important to first consider their delivery and acceptability for the target. This study aimed at determining individual and unit-related factors associated with increased odds of non-response based on hepatitis C virus screening in primary healthcare. Design Primary healthcare units (PHCUs) were extracted from the Register of Health Care Centres. Each of the PHCUs was to enrol adult patients selected on a random basis. Data on the recruitment of PHCUs and patients were analysed. Multilevel modelling was applied to investigate individual and unit-related factors associated with non-response. Multilevel logistic model was developed with fixed effects and only a random intercept for the unit. Preliminary analysis included a random effect for unit and each of the individual or PHCU covariates separately. For each of the PHCU covariates, we applied a two-level model with individual covariates, unit random effect and a single fixed effect of this unit covariate. Setting This study was conducted in primary care units in selected provinces in Poland. Participants A total of 242 PHCUs and 24 480 adults were invited. Of them, 44 PHCUs and 20 939 patients agreed to participate. Both PHCUs and patients were randomly selected. Results Data on 44 PHCUs and 24 480 patients were analysed. PHCU-level factors and recruitment strategies were important predictors of non-response. Unit random effect was significant in all models. Larger and private units reported higher non-response rates, while for those with a history of running public health programmes the odds of non-response was lower. Proactive recruitment, more working hours devoted to the project and patient resulted in higher acceptance of the project. Higher number of personnel had no such effect. Conclusions Prior to the implementation of public health programme, several factors that could hinder its execution should be addressed. PMID:27927665

What affects response rates in primary healthcare-based programmes? An analysis of individual and unit-related factors associated with increased odds of non-response based on HCV screening in the general population in Poland.

PubMed

Parda, Natalia; Stępień, Małgorzata; Zakrzewska, Karolina; Madaliński, Kazimierz; Kołakowska, Agnieszka; Godzik, Paulina; Rosińska, Magdalena

2016-12-07

Response rate in public health programmes may be a limiting factor. It is important to first consider their delivery and acceptability for the target. This study aimed at determining individual and unit-related factors associated with increased odds of non-response based on hepatitis C virus screening in primary healthcare. Primary healthcare units (PHCUs) were extracted from the Register of Health Care Centres. Each of the PHCUs was to enrol adult patients selected on a random basis. Data on the recruitment of PHCUs and patients were analysed. Multilevel modelling was applied to investigate individual and unit-related factors associated with non-response. Multilevel logistic model was developed with fixed effects and only a random intercept for the unit. Preliminary analysis included a random effect for unit and each of the individual or PHCU covariates separately. For each of the PHCU covariates, we applied a two-level model with individual covariates, unit random effect and a single fixed effect of this unit covariate. This study was conducted in primary care units in selected provinces in Poland. A total of 242 PHCUs and 24 480 adults were invited. Of them, 44 PHCUs and 20 939 patients agreed to participate. Both PHCUs and patients were randomly selected. Data on 44 PHCUs and 24 480 patients were analysed. PHCU-level factors and recruitment strategies were important predictors of non-response. Unit random effect was significant in all models. Larger and private units reported higher non-response rates, while for those with a history of running public health programmes the odds of non-response was lower. Proactive recruitment, more working hours devoted to the project and patient resulted in higher acceptance of the project. Higher number of personnel had no such effect. Prior to the implementation of public health programme, several factors that could hinder its execution should be addressed. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Testing self-regulation interventions to increase walking using factorial randomized N-of-1 trials.

PubMed

Sniehotta, Falko F; Presseau, Justin; Hobbs, Nicola; Araújo-Soares, Vera

2012-11-01

To investigate the suitability of N-of-1 randomized controlled trials (RCTs) as a means of testing the effectiveness of behavior change techniques based on self-regulation theory (goal setting and self-monitoring) for promoting walking in healthy adult volunteers. A series of N-of-1 RCTs in 10 normal and overweight adults ages 19-67 (M = 36.9 years). We randomly allocated 60 days within each individual to text message-prompted daily goal-setting and/or self-monitoring interventions in accordance with a 2 (step-count goal prompt vs. alternative goal prompt) × 2 (self-monitoring: open vs. blinded Omron-HJ-113-E pedometer) factorial design. Aggregated data were analyzed using random intercept multilevel models. Single cases were analyzed individually. The primary outcome was daily pedometer step counts over 60 days. Single-case analyses showed that 4 participants significantly increased walking: 2 on self-monitoring days and 2 on goal-setting days, compared with control days. Six participants did not benefit from the interventions. In aggregated analyses, mean step counts were higher on goal-setting days (8,499.9 vs. 7,956.3) and on self-monitoring days (8,630.3 vs. 7,825.9). Multilevel analyses showed a significant effect of the self-monitoring condition (p = .01), the goal-setting condition approached significance (p = .08), and there was a small linear increase in walking over time (p = .03). N-of-1 randomized trials are a suitable means to test behavioral interventions in individual participants.

Interception of rainfall and surface runoff in the Brazilian Cerrado

NASA Astrophysics Data System (ADS)

Tarso Oliveira, Paulo; Wendland, Edson; Nearing, Mark; Perea Martins, João

2014-05-01

The Brazilian Cerrado plays a fundamental role in water resources dynamics because it distributes fresh water to the largest basins in Brazil and South America. In recent decades, the native Cerrado vegetation has increasingly been replaced by agricultural crops and pasture. These land cover and land use changes have altered the hydrological processes. Meanwhile, little is known about the components of the water balance in the Brazilian Cerrado, mainly because the experimental field studies in this region are scarce or nonexistent. The objective of this study was to evaluate two hydrological processes under native Cerrado vegetation, the canopy interception (CI) and the surface runoff (R). The Cerrado physiognomy was classified as "cerrado sensu stricto denso" with an absolute density of 15,278 trees ha-1, and a basal area of 11.44 m2 ha-1. We measured the gross rainfall (P) from an automated tipping bucket rain gauge (model TB4) located in a tower with 11 m of height on the Cerrado. Throughfall (TF) was obtained from 15 automated tipping bucket rain gauges (model Davis) spread below the Cerrado vegetation and randomly relocated every month during the wet season. Stemflow (SF) was measured on 12 trees using a plastic hose wrapped around the trees trunks, sealed with neutral silicone sealant, and a bucket to store the water. The canopy interception was computed by the difference between P and the sum of TF and SF. Surface runoff under undisturbed Cerrado was collected in three plots of 100 m2(5 x 20 m) in size and slope steepness of approximately 0.09 m m-1. The experimental study was conducted between January 2012 and November 2013. We found TF of 81.0% of P and SF of 1.6% of P, i.e. the canopy interception was calculated at 17.4% of P. There was a statistically significant correlation (p < 0.05) between gross rainfall and TF, SF, and CI with correlation coefficients r > 0.8. Our results suggest that the rainfall intensity, the characteristics of the trees trunks (crooked and twisted) and stand structure are the main factors that have influenced CI. The average surface runoff under undisturbed Cerrado was less than 1% of the P, and did not have significant correlation (p > 0.05) with P, but had a significant correlation with maximum 30 minute rainfall intensity (I30). This low value for surface runoff indicates that the forest ?oor has a strong influence over surface runoff generation under undisturbed Cerrado. This process is poorly studied; however, we believe this can be a key to understanding the surface runoff generation under undisturbed Cerrado, and in other tropical vegetation, such as the Amazon rainforest.

More Precise Estimation of Lower-Level Interaction Effects in Multilevel Models.

PubMed

Loeys, Tom; Josephy, Haeike; Dewitte, Marieke

2018-01-01

In hierarchical data, the effect of a lower-level predictor on a lower-level outcome may often be confounded by an (un)measured upper-level factor. When such confounding is left unaddressed, the effect of the lower-level predictor is estimated with bias. Separating this effect into a within- and between-component removes such bias in a linear random intercept model under a specific set of assumptions for the confounder. When the effect of the lower-level predictor is additionally moderated by another lower-level predictor, an interaction between both lower-level predictors is included into the model. To address unmeasured upper-level confounding, this interaction term ought to be decomposed into a within- and between-component as well. This can be achieved by first multiplying both predictors and centering that product term next, or vice versa. We show that while both approaches, on average, yield the same estimates of the interaction effect in linear models, the former decomposition is much more precise and robust against misspecification of the effects of cross-level and upper-level terms, compared to the latter.

15 CFR 742.13 - Communications intercepting devices; software and technology for communications intercepting...

Code of Federal Regulations, 2014 CFR

2014-01-01

...; software and technology for communications intercepting devices. 742.13 Section 742.13 Commerce and Foreign... Communications intercepting devices; software and technology for communications intercepting devices. (a) License... wire, oral, or electronic communications (ECCNs 5A001.f.1 and 5A980); and for related “software...

Rainfall interception by tree crown and leaf litter: an interactive process

Treesearch

Xiang Li; Qingfu Xiao; Jianzhi Niu; Salli Dymond; E. Gregory McPherson; Natalie van Doorn; Xinxiao Yu; Baoyuan Xie; Kebin Zhang; Jiao Li

2017-01-01

Rainfall interception research in forest ecosystems usually focuses on interception by either tree crown or leaf litter, although the 2 components interact when rainfall occurs. A process-based study was conducted to jointly measure rainfall interception by crown and litter and the interaction between the 2 interception processes for 4 tree species (...

Air - water temperature relationships in the trout streams of southeastern Minnesota’s carbonate - sandstone landscape

USGS Publications Warehouse

Krider, Lori A.; Magner, Joseph A.; Perry, Jim; Vondracek, Bruce C.; Ferrington, Leonard C.

2013-01-01

Carbonate-sandstone geology in southeastern Minnesota creates a heterogeneous landscape of springs, seeps, and sinkholes that supply groundwater into streams. Air temperatures are effective predictors of water temperature in surface-water dominated streams. However, no published work investigates the relationship between air and water temperatures in groundwater-fed streams (GWFS) across watersheds. We used simple linear regressions to examine weekly air-water temperature relationships for 40 GWFS in southeastern Minnesota. A 40-stream, composite linear regression model has a slope of 0.38, an intercept of 6.63, and R2 of 0.83. The regression models for GWFS have lower slopes and higher intercepts in comparison to surface-water dominated streams. Regression models for streams with high R2 values offer promise for use as predictive tools for future climate conditions. Climate change is expected to alter the thermal regime of groundwater-fed systems, but will do so at a slower rate than surface-water dominated systems. A regression model of intercept vs. slope can be used to identify streams for which water temperatures are more meteorologically than groundwater controlled, and thus more vulnerable to climate change. Such relationships can be used to guide restoration vs. management strategies to protect trout streams.

High-throughput estimation of incident light, light interception and radiation-use efficiency of thousands of plants in a phenotyping platform.

PubMed

Cabrera-Bosquet, Llorenç; Fournier, Christian; Brichet, Nicolas; Welcker, Claude; Suard, Benoît; Tardieu, François

2016-10-01

Light interception and radiation-use efficiency (RUE) are essential components of plant performance. Their genetic dissections require novel high-throughput phenotyping methods. We have developed a suite of methods to evaluate the spatial distribution of incident light, as experienced by hundreds of plants in a glasshouse, by simulating sunbeam trajectories through glasshouse structures every day of the year; the amount of light intercepted by maize (Zea mays) plants via a functional-structural model using three-dimensional (3D) reconstructions of each plant placed in a virtual scene reproducing the canopy in the glasshouse; and RUE, as the ratio of plant biomass to intercepted light. The spatial variation of direct and diffuse incident light in the glasshouse (up to 24%) was correctly predicted at the single-plant scale. Light interception largely varied between maize lines that differed in leaf angles (nearly stable between experiments) and area (highly variable between experiments). Estimated RUEs varied between maize lines, but were similar in two experiments with contrasting incident light. They closely correlated with measured gas exchanges. The methods proposed here identified reproducible traits that might be used in further field studies, thereby opening up the way for large-scale genetic analyses of the components of plant performance. © 2016 INRA New Phytologist © 2016 New Phytologist Trust.

New Directions in Software Quality Assurance Automation

DTIC Science & Technology

2009-06-01

generation process. 4.1 Parameterized Safety Analysis We can do a qualitative analysis as well and ask questions like “ what has contributed to this...the probability of interception p1 in the previous example, we can determine what impact those parameters have on the probability of hazardous...assumed that the AEG is traversed top-down and left-to-right and only once to produce a particular event trace Randomized decisions about what

Spectral estimates of intercepted solar radiation by corn and soybean canopies

NASA Technical Reports Server (NTRS)

Gallo, K. P.; Brooks, C. C.; Daughtry, C. S. T.; Bauer, M. E.; Vanderbilt, V. C.

1982-01-01

Attention is given to the development of methods for combining spectral and meteorological data in crop yield models which are capable of providing accurate estimates of crop condition and yields throughout the growing season. The present investigation is concerned with initial tests of these concepts using spectral and agronomic data acquired in controlled experiments. The data were acquired at the Purdue University Agronomy Farm, 10 km northwest of West Lafayette, Indiana. Data were obtained throughout several growing seasons for corn and soybeans. Five methods or models for predicting yields were examined. On the basis of the obtained results, it is concluded that estimating intercepted solar radiation using spectral data is a viable approach for merging spectral and meteorological data in crop yield models.

Accelerated longitudinal designs: An overview of modelling, power, costs and handling missing data.

PubMed

Galbraith, Sally; Bowden, Jack; Mander, Adrian

2017-02-01

Longitudinal studies are often used to investigate age-related developmental change. Whereas a single cohort design takes a group of individuals at the same initial age and follows them over time, an accelerated longitudinal design takes multiple single cohorts, each one starting at a different age. The main advantage of an accelerated longitudinal design is its ability to span the age range of interest in a shorter period of time than would be possible with a single cohort longitudinal design. This paper considers design issues for accelerated longitudinal studies. A linear mixed effect model is considered to describe the responses over age with random effects for intercept and slope parameters. Random and fixed cohort effects are used to cope with the potential bias accelerated longitudinal designs have due to multiple cohorts. The impact of other factors such as costs and the impact of dropouts on the power of testing or the precision of estimating parameters are examined. As duration-related costs increase relative to recruitment costs the best designs shift towards shorter duration and eventually cross-sectional design being best. For designs with the same duration but differing interval between measurements, we found there was a cutoff point for measurement costs relative to recruitment costs relating to frequency of measurements. Under our model of 30% dropout there was a maximum power loss of 7%.

Therapeutic alliance in a randomized clinical trial for bulimia nervosa

PubMed Central

Accurso, Erin C.; Fitzsimmons-Craft, Ellen E.; Ciao, Anna; Cao, Li; Crosby, Ross D.; Smith, Tracey L.; Klein, Marjorie H.; Mitchell, James E.; Crow, Scott J.; Wonderlich, Stephen A.; Peterson, Carol B.

2015-01-01

Objective This study examined the temporal relation between therapeutic alliance and outcome in two treatments for bulimia nervosa (BN). Method Eighty adults with BN symptoms were randomized to 21 sessions of integrative cognitive-affective therapy (ICAT) or enhanced cognitive-behavioral therapy (CBT-E). Bulimic symptoms (i.e., frequency of binge eating and purging) were assessed at each session and post-treatment. Therapeutic alliance (Working Alliance Inventory) was assessed at sessions 2, 8, 14, and post-treatment. Repeated-measures analyses using linear mixed models with random intercepts were conducted to determine differences in alliance growth by treatment and patient characteristics. Mixed-effects models examined the relation between alliance and symptom improvement. Results Overall, patients in both treatments reported strong therapeutic alliances. Regardless of treatment, greater therapeutic alliance between (but not within) subjects predicted greater reductions in bulimic behavior; reductions in bulimic behavior also predicted improved alliance. Patients with higher depression, anxiety, or emotion dysregulation had a stronger therapeutic alliance in CBT-E than ICAT, while those with more intimacy problems had greater improvement in therapeutic alliance in ICAT compared to CBT-E. Conclusions Therapeutic alliance has a unique impact on outcome, independent of the impact of symptom improvement on alliance. Within- and between-subject effects revealed that changes in alliance over time did not predict symptom improvement, but rather that individuals who had a stronger alliance overall had better bulimic symptom outcomes. These findings indicate that therapeutic alliance is an important predictor of outcome in the treatment of BN. PMID:25894667

Therapeutic alliance in a randomized clinical trial for bulimia nervosa.

PubMed

Accurso, Erin C; Fitzsimmons-Craft, Ellen E; Ciao, Anna; Cao, Li; Crosby, Ross D; Smith, Tracey L; Klein, Marjorie H; Mitchell, James E; Crow, Scott J; Wonderlich, Stephen A; Peterson, Carol B

2015-06-01

This study examined the temporal relation between therapeutic alliance and outcome in two treatments for bulimia nervosa (BN). Eighty adults with BN symptoms were randomized to 21 sessions of integrative cognitive-affective therapy (ICAT) or enhanced cognitive-behavioral therapy (CBT-E). Bulimic symptoms (i.e., frequency of binge eating and purging) were assessed at each session and posttreatment. Therapeutic alliance (Working Alliance Inventory) was assessed at Sessions 2, 8, 14, and posttreatment. Repeated-measures analyses using linear mixed models with random intercepts were conducted to determine differences in alliance growth by treatment and patient characteristics. Mixed-effects models examined the relation between alliance and symptom improvement. Overall, patients in both treatments reported strong therapeutic alliances. Regardless of treatment, greater therapeutic alliance between (but not within) subjects predicted greater reductions in bulimic behavior; reductions in bulimic behavior also predicted improved alliance. Patients with higher depression, anxiety, or emotion dysregulation had a stronger therapeutic alliance in CBT-E than ICAT, while those with more intimacy problems had greater improvement in therapeutic alliance in ICAT compared to CBT-E. Therapeutic alliance has a unique impact on outcome, independent of the impact of symptom improvement on alliance. Within- and between-subjects effects revealed that changes in alliance over time did not predict symptom improvement, but rather that individuals who had a stronger alliance overall had better bulimic symptom outcomes. These findings indicate that therapeutic alliance is an important predictor of outcome in the treatment of BN. (c) 2015 APA, all rights reserved).

Field Evaluation of Model II of the Computer-Based, Individual Trainer for the Radar Intercept Officer

DTIC Science & Technology

1974-07-01

of an (almost) completely automated CAI capability for teaching skills for the Radar Intercept Officer’s (RIO’s) job. Contributions made by this...expected) from such features. At present, the utility of developing CAI materials for teaching the utiliza- tion of the AWG-9 system for maintaining...this complexity is necessary even though the trainer -as designed to teach only basic skills used in this performance. Therefore, chc details of the

Ballistic intercept missions to Comet Encke

NASA Technical Reports Server (NTRS)

Mumma, M. (Compiler)

1975-01-01

The optimum ballistic intercept of a spacecraft with the comet Encke is determined. The following factors are considered in the analysis: energy requirements, encounter conditions, targeting error, comet activity, spacecraft engineering requirements and restraints, communications, and scientific return of the mission. A baseline model is formulated which includes the basic elements necessary to estimate the scientific return for the different missions considered. Tradeoffs which have major impact on the cost and/or scientific return of a ballistic mission to comet Encke are identified and discussed. Recommendations are included.

Eye movements and manual interception of ballistic trajectories: effects of law of motion perturbations and occlusions.

PubMed

Delle Monache, Sergio; Lacquaniti, Francesco; Bosco, Gianfranco

2015-02-01

Manual interceptions are known to depend critically on integration of visual feedback information and experience-based predictions of the interceptive event. Within this framework, coupling between gaze and limb movements might also contribute to the interceptive outcome, since eye movements afford acquisition of high-resolution visual information. We investigated this issue by analyzing subjects' head-fixed oculomotor behavior during manual interceptions. Subjects moved a mouse cursor to intercept computer-generated ballistic trajectories either congruent with Earth's gravity or perturbed with weightlessness (0 g) or hypergravity (2 g) effects. In separate sessions, trajectories were either fully visible or occluded before interception to enforce visual prediction. Subjects' oculomotor behavior was classified in terms of amounts of time they gazed at different visual targets and of overall number of saccades. Then, by way of multivariate analyses, we assessed the following: (1) whether eye movement patterns depended on targets' laws of motion and occlusions; and (2) whether interceptive performance was related to the oculomotor behavior. First, we found that eye movement patterns depended significantly on targets' laws of motion and occlusion, suggesting predictive mechanisms. Second, subjects coupled differently oculomotor and interceptive behavior depending on whether targets were visible or occluded. With visible targets, subjects made smaller interceptive errors if they gazed longer at the mouse cursor. Instead, with occluded targets, they achieved better performance by increasing the target's tracking accuracy and by avoiding gaze shifts near interception, suggesting that precise ocular tracking provided better trajectory predictions for the interceptive response.

Hair mercury concentrations and in vitro fertilization (IVF) outcomes among women from a fertility clinic

PubMed Central

Ehrlich, Shelley; Smith, Kristen; Williams, Paige L.; Chavarro, Jorge E.; Batsis, Maria; Toth, Thomas L.; Hauser, Russ

2015-01-01

Total hair mercury (Hg) was measured among 205 women undergoing in vitro fertilization (IVF) treatment and the association with prospectively collected IVF outcomes (229 IVF cycles) was evaluated. Hair Hg levels (median=0.62 ppm, range: 0.03-5.66 ppm) correlated with fish intake (r=0.59), and exceeded the recommended EPA reference of 1ppm in 33% of women. Generalized linear mixed models with random intercepts accounting for within-woman correlations across treatment cycles were used to evaluate the association of hair Hg with IVF outcomes adjusted for age, body mass index, race, smoking status, infertility diagnosis, and protocol type. Hair Hg levels were not related to ovarian stimulation outcomes (peak estradiol levels, total and mature oocyte yields) or to fertilization rate, embryo quality, clinical pregnancy rate or live birth rate. PMID:25601638

Mother and Father Adjustment during Early Parenthood: The Roles of Infant Temperament and Coparenting Relationship Quality

PubMed Central

Solmeyer, Anna; Feinberg, Mark E

2011-01-01

We explored how parent gender, infant temperament, and coparenting dynamics worked together to shape mothers’ and fathers’ depressive symptoms, stress, and parental efficacy during early parenthood. We were interested in the coparenting relationship as a context that shapes how parents respond to their infant’s temperamental qualities. Participants were 139 couples who had recently given birth to their first child. Parent reports of temperament were collected when the infant was 4–8 months old and reports of coparenting and parent adjustment were collected at 13 months. Two-level random intercept models revealed interactions among temperament and coparenting, highlighting the family system as a context for how men and women adapt to their parenting role. There was little evidence for mother-father differences in these associations. PMID:21868100

Compound simulator IR radiation characteristics test and calibration

NASA Astrophysics Data System (ADS)

Li, Yanhong; Zhang, Li; Li, Fan; Tian, Yi; Yang, Yang; Li, Zhuo; Shi, Rui

2015-10-01

The Hardware-in-the-loop simulation can establish the target/interference physical radiation and interception of product flight process in the testing room. In particular, the simulation of environment is more difficult for high radiation energy and complicated interference model. Here the development in IR scene generation produced by a fiber array imaging transducer with circumferential lamp spot sources is introduced. The IR simulation capability includes effective simulation of aircraft signatures and point-source IR countermeasures. Two point-sources as interference can move in two-dimension random directions. For simulation the process of interference release, the radiation and motion characteristic is tested. Through the zero calibration for optical axis of simulator, the radiation can be well projected to the product detector. The test and calibration results show the new type compound simulator can be used in the hardware-in-the-loop simulation trial.

The Potential for Mindfulness-Based Intervention in Workplace Mental Health Promotion: Results of a Randomized Controlled Trial

PubMed Central

Huang, Shu-Ling; Li, Ren-Hau; Huang, Feng-Ying; Tang, Feng-Cheng

2015-01-01

Objectives This study aims to intensively evaluate the effectiveness of mindfulness-based intervention (MBI) on mental illness risks (including psychological distress, prolonged fatigue, and perceived stress) and job strain (job control and job demands) for employees with poor mental health. Methods A longitudinal research design was adopted. In total, 144 participants were randomized to the intervention group or the control group. The intervention group participated in MBI for eight weeks. Measurements were collected for both groups at five time points: at pre-intervention (T1), at mid-intervention (T2), at the completion of intervention (T3), four weeks after intervention (T4), and eight weeks after intervention (T5). Data were analyzed according to the intention-to-treat principle. A linear mixed model with two levels was employed to analyze the repeated measurement data. Results Compared with the control group, the intercepts (means at T3) for the intervention group were significantly lower on psychological distress, prolonged fatigue, and perceived stress when MBI was completed. Even with the demographic variables controlled, the positive effects remained. For growth rates of prolonged fatigue and perceived stress, participants in the intervention group showed a steeper decrease than did the participants in the control group. Regarding job strain, although the intercept (mean at T3) of job demands showed a significant decline when BMI was completed, the significance disappeared when the demographic variables were controlled. Moreover, the other results for job control and job demands did not show promising findings. Conclusion As a workplace health promotion program, the MBI seems to have potential in improving mental illness risks for employees with poor mental health. However, there was insufficient evidence to support its effect on mitigating job strain. Further research on maintaining the positive effects on mental health for the long term and on developing innovative MBI to suit job strain are recommended. Trial Registration ClinicalTrials.gov NCT02241070 PMID:26367270

Digital-transport model study of Diisopropylmethylphosphonate (DIMP) ground-water contamination at the Rocky Mountain Arsenal, Colorado

USGS Publications Warehouse

Warner, James W.

1979-01-01

Diisopropylmethylphosphonate (DIMP) is an organic compound produced as a by-product of the manufacture and detoxification of GB nerve gas. Ground-water contamination by DIMP from the disposal of wastes into unlined surface ponds at the Rocky Mountain Arsenal occurred from 1952 to 1956. A digital-transport model was used to determine the effects on ground-water movement and on DIMP concentrations in the ground water of a bentonite barrier in the aquifer near the northern boundary of the arsenal. The transport model is based on an iterative-alternating-direction-implicit mathematical solution of the ground-water-flow equation coupled with a method-of-characteristics solution of the solute-transport equation. The model assumes conservative (nonreactive) transient transport of DIMP and steady-state ground-water flow. In the model simulations, a bentonite barrier was assumed that was impermeable and penetrated the entire saturated thickness of the aquifer. Ground water intercepted by the barrier was assumed to be pumped by wells located south (upgradient) of the barrier, to be treated to remove DIMP, and to be recharged by pits or wells to the aquifer north (downgradient) of the barrier. The amount of DIMP transported across the northern boundary of the arsenal was substantially reduced by a ground-water-barrier system of this type. For a 1,500-foot-long bentonite barrier located along the northern boundary of the arsenal near D Street, about 50 percent of the DIMP that would otherwise cross the boundary would be intercepted by the barrier. This barrier configuration and location were proposed by the U.S. Army. Of the ground water with DIMP concentrations greater than 500 micrograms per liter, the safe DIMP-concentration level determined by the U.S. Army, about 72 percent would be intercepted by the barrier system. The amount of DIMP underflow intercepted may be increased to 65 percent by doubling the pumpage, or to 73 percent by doubling the length of the barrier. (Kosco-USGS)

Challenges in Estimating Evapotranspiration of Young Sparse Stands in a Boreal Forest of Eastern-Canada

NASA Astrophysics Data System (ADS)

Hadiwijaya, B.; Nadeau, D.; Pépin, S.

2017-12-01

Forest evapotranspiration is the sum of transpiration, evaporation from intercepted rainfall by the canopy and soil evaporation, each component being governed by distinct time scales and mechanisms. Therefore, to develop a simple, yet realistic, model to estimate evapotranspiration over forested areas, field measurements must capture the full chronological sequence of events taking place following rainfall. This becomes a challenge in the case of young sparse forest stands due to large diversity in canopy covers and leaf area indices, which leads to strong spatial variation in intercepted rainfall by the canopy. Unfortunately, very few studies have focused on transition between the dry and wet canopy conditions. The objectives of this study are to investigate each element of rain interception and intercepted water loss, to characterize water loss partitioning processes based on precipitation rate, elapsed time and time-sequence events. To do this, we conducted a summer field campaign at Forêt Montmorency (47°N, 71°W), in southern Québec, Canada, started from early May until late October. The site is characterized by a humid continental climate, with a mean annual precipitation of 1500 mm. The site is located at the boreal forest region, in the balsam for-white birch ecosystem, whose growing season typically extends from May until October. Six measurement plots were established around two micrometeorological towers located in juvenile and sapling forest stands. Five sap flow probes to measure transpiration and a set of rainfall interception instruments (measuring throughfall, free throughfall and stemflow separately) have been deployed on each plot. Initial results presented will include the estimated evapotranspiration rate and soil evaporation measured using eddy covariance method, transpiration rate and high resolution analysis of rainfall interception.

Development of a table tennis robot for ball interception using visual feedback

NASA Astrophysics Data System (ADS)

Parnichkun, Manukid; Thalagoda, Janitha A.

2016-07-01

This paper presents a concept of intercepting a moving table tennis ball using a robot. The robot has four degrees of freedom(DOF) which are simplified in such a way that The system is able to perform the task within the bounded limit. It employs computer vision to localize the ball. For ball identification, Colour Based Threshold Segmentation(CBTS) and Background Subtraction(BS) methodologies are used. Coordinate Transformation(CT) is employed to transform the data, which is taken based on camera coordinate frame to the general coordinate frame. The sensory system consisted of two HD Web Cameras. The computation time of image processing from web cameras is long .it is not possible to intercept table tennis ball using only image processing. Therefore the projectile motion model is employed to predict the final destination of the ball.

Recovery of high speed memory scanning after transient global amnesia: a case report.

PubMed

Okura, M; Tomotake, M; Mori, K; Ikuta, T

1996-12-01

We described the case of a 59 year old female with transient global amnesia (TGA) who had been examined neuropsychologically using Sternberg's paradigm and a random number generation (RNG) task on the following day, 1 week and 4 weeks after a TGA episode. The slope value of the linear function, a measure of cognitive memory scanning speed, decreased with time and showed a marked decrease 1 week after TGA, suggesting that the stage of serial and exhaustive scanning recovered within 1 week. The zero-intercept value, on the other hand, increased during 1 week but decreased 4 weeks later and was not related directly to recovery from TGA. The performance in RNG task improved 1 week later, but deteriorated 4 weeks after the episode. Such a change in RNG was in accordance with that of the zero-intercept value, predicting a relationship. It is concluded that the subclinical memory deficit, detected with these tasks, persisted longer than clinical recovery from TGA.

REGRES: A FORTRAN-77 program to calculate nonparametric and ``structural'' parametric solutions to bivariate regression equations

NASA Astrophysics Data System (ADS)

Rock, N. M. S.; Duffy, T. R.

REGRES allows a range of regression equations to be calculated for paired sets of data values in which both variables are subject to error (i.e. neither is the "independent" variable). Nonparametric regressions, based on medians of all possible pairwise slopes and intercepts, are treated in detail. Estimated slopes and intercepts are output, along with confidence limits, Spearman and Kendall rank correlation coefficients. Outliers can be rejected with user-determined stringency. Parametric regressions can be calculated for any value of λ (the ratio of the variances of the random errors for y and x)—including: (1) major axis ( λ = 1); (2) reduced major axis ( λ = variance of y/variance of x); (3) Y on Xλ = infinity; or (4) X on Y ( λ = 0) solutions. Pearson linear correlation coefficients also are output. REGRES provides an alternative to conventional isochron assessment techniques where bivariate normal errors cannot be assumed, or weighting methods are inappropriate.

The influence of canopy shading of snow on effective albedo in forested environments

NASA Astrophysics Data System (ADS)

Webster, C.; Jonas, T.

2017-12-01

The overlap of highly reflective snow and absorbent forested areas creates strong heterogeneity in the effective surface albedo compared to forest-free areas. Current errors in calculations of effective forest snow albedo arise due to uncertainties in how models should treat masking of snow by vegetation but improvement of local and large scale models is currently limited by a lack of measurements that demonstrate both spatial and temporal variability over forests. We present above-canopy measurements of winter-time effective forest snow albedo using up- and down-looking radiometers mounted on an octocopter UAV for a total of fifteen flights on eight different days. Ground-view fractions across the flight path were between 0.12 and 0.81. Correlations between effective albedo and both ground-view fraction and canopy height were statistically significant during 14 out of 15 flights, but varied between flights due to solar angle and snow cover. Measured effective albedo across the flight path differed by up to 0.33 during snow-on canopy conditions. A comparison between maximum interception and no interception showed effective albedo varied by up 0.17, which was the same variation between effective albedo during high (46°) and low (23°) solar elevation angles. Temporal and spatial variations in effective albedo caused by canopy shading of the snow surface are therefore as important as temporal variations caused by interception of snow by the canopy. Calculation of effective albedo over forested areas therefore requires careful consideration of canopy height, canopy coverage, solar angle and interception load. The results of this study should be used to inform snow albedo and canopy structure parametrisations in local and larger scale land surface models.

Eye movement accuracy determines natural interception strategies.

PubMed

Fooken, Jolande; Yeo, Sang-Hoon; Pai, Dinesh K; Spering, Miriam

2016-11-01

Eye movements aid visual perception and guide actions such as reaching or grasping. Most previous work on eye-hand coordination has focused on saccadic eye movements. Here we show that smooth pursuit eye movement accuracy strongly predicts both interception accuracy and the strategy used to intercept a moving object. We developed a naturalistic task in which participants (n = 42 varsity baseball players) intercepted a moving dot (a "2D fly ball") with their index finger in a designated "hit zone." Participants were instructed to track the ball with their eyes, but were only shown its initial launch (100-300 ms). Better smooth pursuit resulted in more accurate interceptions and determined the strategy used for interception, i.e., whether interception was early or late in the hit zone. Even though early and late interceptors showed equally accurate interceptions, they may have relied on distinct tactics: early interceptors used cognitive heuristics, whereas late interceptors' performance was best predicted by pursuit accuracy. Late interception may be beneficial in real-world tasks as it provides more time for decision and adjustment. Supporting this view, baseball players who were more senior were more likely to be late interceptors. Our findings suggest that interception strategies are optimally adapted to the proficiency of the pursuit system.

Recurrent bridgehead effects accelerate global alien ant spread.

PubMed

Bertelsmeier, Cleo; Ollier, Sébastien; Liebhold, Andrew M; Brockerhoff, Eckehard G; Ward, Darren; Keller, Laurent

2018-05-22

Biological invasions are a major threat to biological diversity, agriculture, and human health. To predict and prevent new invasions, it is crucial to develop a better understanding of the drivers of the invasion process. The analysis of 4,533 border interception events revealed that at least 51 different alien ant species were intercepted at US ports over a period of 70 years (1914-1984), and 45 alien species were intercepted entering New Zealand over a period of 68 years (1955-2013). Most of the interceptions did not originate from species' native ranges but instead came from invaded areas. In the United States, 75.7% of the interceptions came from a country where the intercepted ant species had been previously introduced. In New Zealand, this value was even higher, at 87.8%. There was an overrepresentation of interceptions from nearby locations (Latin America for species intercepted in the United States and Oceania for species intercepted in New Zealand). The probability of a species' successful establishment in both the United States and New Zealand was positively related to the number of interceptions of the species in these countries. Moreover, species that have spread to more continents are also more likely to be intercepted and to make secondary introductions. This creates a positive feedback loop between the introduction and establishment stages of the invasion process, in which initial establishments promote secondary introductions. Overall, these results reveal that secondary introductions act as a critical driver of increasing global rates of invasions.

Trajectories of teacher-student warmth and conflict at the transition to middle school: Effects on academic engagement and achievement.

PubMed

Hughes, Jan N; Cao, Qian

2018-04-01

Using piece-wise longitudinal trajectory analysis, this study investigated trajectories of teacher-reported warmth and conflict in their relationships with students 4years prior to and 3years following the transition to middle school in a sample of 550 academically at-risk and ethnically diverse adolescents. At the transition to middle school, teacher reports of warmth showed a significant drop (shift in intercept), above age-related declines. Both warmth and conflict declined across the middle school years. Structural equation modeling (SEM) tested effects of the shifts in intercept and the post-transition slopes on reading and math achievement, teacher-rated engagement, and student-reported school belonging 3years post-transition, above pre-transition levels of the outcome. For warmth, a drop in intercept predicted lower math scores and engagement, and a more positive slope predicted higher engagement. For conflict, an increase in intercept and a negative slope predicted lower engagement. Implications of findings for reducing normative declines in academic engagement in middle school are discussed. Copyright © 2017 Society for the Study of School Psychology. Published by Elsevier Ltd. All rights reserved.

Do executive functions explain the covariance between internalizing and externalizing behaviors?

PubMed

Hatoum, Alexander S; Rhee, Soo Hyun; Corley, Robin P; Hewitt, John K; Friedman, Naomi P

2017-11-16

This study examined whether executive functions (EFs) might be common features of internalizing and externalizing behavior problems across development. We examined relations between three EF latent variables (a common EF factor and factors specific to updating working memory and shifting sets), constructed from nine laboratory tasks administered at age 17, to latent growth intercept (capturing stability) and slope (capturing change) factors of teacher- and parent-reported internalizing and externalizing behaviors in 885 individual twins aged 7 to 16 years. We then estimated the proportion of intercept-intercept and slope-slope correlations predicted by EF as well as the association between EFs and a common psychopathology factor (P factor) estimated from all 9 years of internalizing and externalizing measures. Common EF was negatively associated with the intercepts of teacher-rated internalizing and externalizing behavior in males, and explained 32% of their covariance; in the P factor model, common EF was associated with the P factor in males. Shifting-specific was positively associated with the externalizing slope across sex. EFs did not explain covariation between parent-rated behaviors. These results suggest that EFs are associated with stable problem behavior variation, explain small proportions of covariance, and are a risk factor that that may depend on gender.

Nonlinear isochrones in murine left ventricular pressure-volume loops: how well does the time-varying elastance concept hold?

PubMed

Claessens, T E; Georgakopoulos, D; Afanasyeva, M; Vermeersch, S J; Millar, H D; Stergiopulos, N; Westerhof, N; Verdonck, P R; Segers, P

2006-04-01

The linear time-varying elastance theory is frequently used to describe the change in ventricular stiffness during the cardiac cycle. The concept assumes that all isochrones (i.e., curves that connect pressure-volume data occurring at the same time) are linear and have a common volume intercept. Of specific interest is the steepest isochrone, the end-systolic pressure-volume relationship (ESPVR), of which the slope serves as an index for cardiac contractile function. Pressure-volume measurements, achieved with a combined pressure-conductance catheter in the left ventricle of 13 open-chest anesthetized mice, showed a marked curvilinearity of the isochrones. We therefore analyzed the shape of the isochrones by using six regression algorithms (two linear, two quadratic, and two logarithmic, each with a fixed or time-varying intercept) and discussed the consequences for the elastance concept. Our main observations were 1) the volume intercept varies considerably with time; 2) isochrones are equally well described by using quadratic or logarithmic regression; 3) linear regression with a fixed intercept shows poor correlation (R(2) < 0.75) during isovolumic relaxation and early filling; and 4) logarithmic regression is superior in estimating the fixed volume intercept of the ESPVR. In conclusion, the linear time-varying elastance fails to provide a sufficiently robust model to account for changes in pressure and volume during the cardiac cycle in the mouse ventricle. A new framework accounting for the nonlinear shape of the isochrones needs to be developed.

Amotosalen: Allogeneic Cellular Immunotherapies system, INTERCEPT Plasma System, INTERCEPT Platelet System, S 59.

PubMed

2003-01-01

Adis CommentsCerus Corporation is developing a variety of pathogen-inactivation systems, based on its Helinx technology. Three of the systems include amotosalen [S 59] as the inactivation compound. Amotosalen is a light-activated, DNA-, RNA-crosslinking psoralen compound, which is used to neutralise pathogens. The systems that utilise amotosalen are called the INTERCEPT Platelet System, the INTERCEPT Plasma System and the Allogeneic Cellular Immunotherapies (ACIT) system. The INTERCEPT Platelet System and INTERCEPT Plasma System are two of the systems that make up Cerus' INTERCEPT Blood Systems. The other system is the INTERCEPT Red Blood Cell System, which contains S 303 as the inactivation compound rather than amotosalen. Cerus' Helinx technology is able to prevent replication of DNA or RNA that is present in pathogens but not in the blood components being treated (e.g. platelets and plasma). When added to the blood components, the inactivation agent (in this case amotosalen) crosses the membrane or cell wall of the pathogen. When activated by light, amotosalen binds to the nucleic acid of the pathogen and prevents replication. This process prevents infection. INTERCEPT Platelet System: Cerus developed its INTERCEPT Platelet System, in collaboration with Baxter Healthcare, for use in blood centres. Platelets are an essential component of the coagulation process and may be required by patients undergoing surgery, cancer chemotherapy, transplantation or with bleeding disorders. The system is made up of an illuminator device, a compound absorption device and a processing kit containing amotosalen. In October 2002, the two companies announced that CE Mark approval had been received for the illuminator device for the INTERCEPT trade mark Blood System. Application of this technology to platelets is the first to be approved. As it is a new technology, the system is currently undergoing process validation in accordance with European Blood Bank GMP requirements. This validation process is currently being conducted in Denmark, France, Germany, Sweden and the UK. Marketing approval applications for the INTERCEPT Platelet System have also been submitted in Australia and Canada. In addition, the regulatory submission process has begun in the US. A phase III trial (EuroSPRITE) has been conducted in 103 patients in Europe with pooled random donor platelets. The platelets were collected using the buffy coat process. Another two 20-patient clinical trials have also been conducted in Europe, as well as a 40-patient trial using platelets collected by an apheresis collection system. Cerus has also conducted a phase III trial (SPRINT) in the US. The trial was conducted in 671 patients and used platelets collected by Baxter's apheresis collection system. INTERCEPT Plasma System: Cerus is also developing the INTERCEPT Plasma System in collaboration with Baxter Healthcare. The system also combines amotosalen, an illumination device and a compound absorption device. The two companies are currently preparing regulatory applications for the INTERCEPT Plasma System for the US. This application will be followed by a submission for CE Mark designation in Europe. Patients undergoing surgery, or transplantation, or with bleeding disorders, may require transfusions of plasma, often to control bleeding. The type of plasma is stored in frozen form and is called fresh frozen plasma (FFP). The INTERCEPT Plasma System is currently in phase IIIc development in the US. Patient enrolment in the trial is still ongoing. The trial is comparing INTERCEPT trade mark Plasma System treated versus untreated FFP in 30 patients with thrombotic thrombocytopenic purpura. Allogeneic Cellular Immunotherapies system: Cerus is also investigating the potential of its Helinx technology to improve the outcome of bone marrow transplantation procedures (used to treat leukaemia and lymphoma) through the treatmatment for many forms of leukaemia and is most effective when the donor is very closely matched to the patient for the major human leucocyte antigen (HLA) groups. As part of the transplant procedure, patients receive donor T cells to improve engraftment of the bone marrow transplant and strengthen the patient's immune system. However, donor T cells expose the patient to a high risk of contracting graft-versus-host disease (GVHD) caused by the proliferation of donor T cells, which attack the patient's healthy tissue. GVHD has a high mortality rate. Cerus' ACIT system has been developed to decrease the stringency of matching donors to patients and to inhibit the ability of donor T cells to cause GVHD. Light-activated amotosalen binds and permanently crosslinks DNA, preventing replication and thus stopping proliferation of donor T cells. Phase I development is currently being conducted in this area in the US using amotosalen as the neutralising agent. Cerus completed a phase I study investigating the safety and tolerability of its ACIT system in 2001. The study was conducted in patients receiving closely matched allogeneic bone marrow transplants for leukaemia. The company is currently collaborating with the National Marrow Donor Program in order to conduct further clinical studies in patients receiving bone marrow transplants from unmatched donors. Cerus has development, manufacturing and marketing agreements with Baxter covering the INTERCEPT Blood Systems, which includes the INTERCEPT Platelet system, the INTERCEPT Plasma System, and the INTERCEPT Red Blood Cell System. Under the terms of the agreements the two companies usually share the very early development activities. Cerus then conducts preclinical and clinical trials, while Baxter is responsible for the development of the systems disposables and devices. Following commercialisation Cerus will supply amotosalen and Baxter will supply the other components of the system and market, sell and distribute the system In January 2001, Cereus announced that it has entered into a collaborative agreement with the Pharmaceutical Division of Kirin Brewery in Japan to develop and market products for stem cell transplantation based on Cerus' proprietary Helinx technology. Under terms of the agreement, Cerus and Kirin will jointly develop the products. Cerus has received an initial license fee of US dollar 1 million. In addition it may receive up to US dollar 11 million in future payments upon achievement of development milestones. Kirin will also fund all development expenses for the Asia-Pacific region and a portion of Cerus' development activities aimed at obtaining product approval in the US. Kirin will market the products in the Asia-Pacific region, including Japan, China, Korea and Australia, and Cerus will receive a specified share of product revenues. Cerus will retain marketing rights in the rest of the world, including the US and Europe.

How is rainfall interception in urban area affected by meteorological parameters?

NASA Astrophysics Data System (ADS)

Zabret, Katarina; Rakovec, Jože; Mikoš, Matjaž; Šraj, Mojca

2017-04-01

Rainfall interception is part of the hydrological cycle. Precipitation, which hits vegetation, is retained on the leaves and branches, from which it eventually evaporates into the atmosphere (interception) or reaches the ground by dripping from the canopy, falling through the gaps (throughfall) and running down the stems (stemflow). The amount of rainfall reaching the ground depends on various meteorological and vegetation parameters. Rainfall, throughfall and stemflow have been measured in the city of Ljubljana, Slovenia since the beginning of 2014. Manual and automatic measurements are performed regularly under Betula pendula and Pinus nigra trees in urban area. In 2014, there were detected 178 rainfall events with total amount of 1672.1 mm. In average B. pendula intercepted 44% of rainfall and P. nigra intercepted 72% of rainfall. In 2015 we have detected 117 events with 1047.4 mm of rainfall, of which 37% was intercepted by B. pendula and 60% by P. nigra. The effect of various meteorological parameters on the rainfall interception was analysed in the study. The parameters included in the analysis were rainfall rate, rainfall duration, drop size distribution (average drop velocity and diameter), average wind speed, and average temperature. The results demonstrate decreasing rainfall interception with longer rainfall duration and higher rainfall intensity although the impact of the latter one is not statistically significant. In the case of very fast or very slow rainfall drops, the interception is higher than for the mean rain drop velocity values. In the case of P. nigra the impact of the rain drop diameter on interception is similar to the one of rain drop velocity while for B. pendula increasing of drop diameter also increases the interception. As expected, interception is higher for warmer events. This trend is more evident for P. nigra than for B. pendula. Furthermore, the amount of intercepted rainfall also increases with wind although it could be relatively high in case of very low wind speeds.

Canopy rainfall partitioning across an urbanization gradient in forest structure as characterized by terrestrial LiDAR

NASA Astrophysics Data System (ADS)

Mesta, D. C.; Van Stan, J. T., II; Yankine, S. A.; Cote, J. F.; Jarvis, M. T.; Hildebrandt, A.; Friesen, J.; Maldonado, G.

2017-12-01

As urbanization expands, greater forest area is shifting from natural stand structures to urban stand structures, like forest fragments and landscaped tree rows. Changes in forest canopy structure have been found to drastically alter the amount of rainwater reaching the surface. However, stormwater management models generally treat all forest structures (beyond needle versus broadleaved) similarly. This study examines the rainfall partitioning of Pinus spp. canopies along a natural-to-urban forest gradient and compares these to canopy structural measurements using terrestrial LiDAR. Throughfall and meteorological observations were also used to estimate parameters of the commonly-used Gash interception model. Preliminary findings indicate that as forest structure changed from natural, closed canopy conditions to semi-closed canopy fragments and, ultimately, to exposed urban landscaping tree rows, the interchange between throughfall and rainfall interception also changed. This shift in partitioning between throughfall and rainfall interception may be linked to intuitive parameters, like canopy closure and density, as well as more complex metrics, like the fine-scale patterning of gaps (ie, lacunarity). Thus, results indicate that not all forests of the same species should be treated the same by stormwater models. Rather, their canopy structural characteristics should be used to vary their hydrometeorological interactions.

Diversion at re-entry using criminogenic CBT: Review and prototypical program development.

PubMed

Heilbrun, Kirk; Pietruszka, Victoria; Thornewill, Alice; Phillips, Sarah; Schiedel, Rebecca

2017-09-01

Society and the criminal justice system prioritize the reduction of reoffending risk as part of any criminal justice intervention. The Sequential Intercept Model identifies five points of interception at which justice-involved individuals can be diverted into a more rehabilitative alternative: (1) law enforcement/emergency services; (2) booking/initial court hearings; (3) jails/courts; (4) re-entry; and (5) community corrections/community support. The present article focuses on diversion as part of Intercept 5 - re-entry planning and specialized services in the community. We describe the challenges associated with diversion at this stage, and review the relevant research. Next, we describe a "criminogenic cognitive behavioral therapy" project that has been developed and implemented as part of a federal re-entry court. Finally, we discuss the implications of the challenges of intervention at this stage, and the recently developed "Re-entry Project," for research, policy, and practice. Copyright © 2017 John Wiley & Sons, Ltd.

Estimation of Whole Plant Photosynthetic Rate of Irwin Mango under Artificial and Natural Lights Using a Three-Dimensional Plant Model and Ray-Tracing.

PubMed

Jung, Dae Ho; Lee, Joon Woo; Kang, Woo Hyun; Hwang, In Ha; Son, Jung Eek

2018-01-04

Photosynthesis is an important physiological response for determination of CO₂ fertilization in greenhouses and estimation of crop growth. In order to estimate the whole plant photosynthetic rate, it is necessary to investigate how light interception by crops changes with environmental and morphological factors. The objectives of this study were to analyze plant light interception using a three-dimensional (3D) plant model and ray-tracing, determine the spatial distribution of the photosynthetic rate, and estimate the whole plant photosynthetic rate of Irwin mango ( Mangifera indica L. cv. Irwin) grown in greenhouses. In the case of mangoes, it is difficult to measure actual light interception at the canopy level due to their vase shape. A two-year-old Irwin mango tree was used to measure the whole plant photosynthetic rate. Light interception and whole plant photosynthetic rate were measured under artificial and natural light conditions using a closed chamber (1 × 1 × 2 m). A 3D plant model was constructed and ray-tracing simulation was conducted for calculating the photosynthetic rate with a two-variable leaf photosynthetic rate model of the plant. Under artificial light, the estimated photosynthetic rate increased from 2.0 to 2.9 μmolCO₂·m -2 ·s -1 with increasing CO₂ concentration. On the other hand, under natural light, the photosynthetic rate increased from 0.2 μmolCO₂·m -2 ·s -1 at 06:00 to a maximum of 7.3 μmolCO₂·m -2 ·s -1 at 09:00, then gradually decreased to -1.0 μmolCO₂·m -2 ·s -1 at 18:00. In validation, simulation results showed good agreement with measured results with R ² = 0.79 and RMSE = 0.263. The results suggest that this method could accurately estimate the whole plant photosynthetic rate and be useful for pruning and adequate CO₂ fertilization.

Quantitative Validation of the Integrated Medical Model (IMM) for ISS Missions

NASA Technical Reports Server (NTRS)

Young, Millennia; Arellano, J.; Boley, L.; Garcia, Y.; Saile, L.; Walton, M.; Kerstman, E.; Reyes, D.; Goodenow, D. A.; Myers, J. G.

2016-01-01

Lifetime Surveillance of Astronaut Health (LSAH) provided observed medical event data on 33 ISS and 111 STS person-missions for use in further improving and validating the Integrated Medical Model (IMM). Using only the crew characteristics from these observed missions, the newest development version, IMM v4.0, will simulate these missions to predict medical events and outcomes. Comparing IMM predictions to the actual observed medical event counts will provide external validation and identify areas of possible improvement. In an effort to improve the power of detecting differences in this validation study, the total over each program ISS and STS will serve as the main quantitative comparison objective, specifically the following parameters: total medical events (TME), probability of loss of crew life (LOCL), and probability of evacuation (EVAC). Scatter plots of observed versus median predicted TMEs (with error bars reflecting the simulation intervals) will graphically display comparisons while linear regression will serve as the statistical test of agreement. Two scatter plots will be analyzed 1) where each point reflects a mission and 2) where each point reflects a condition-specific total number of occurrences. The coefficient of determination (R2) resulting from a linear regression with no intercept bias (intercept fixed at zero) will serve as an overall metric of agreement between IMM and the real world system (RWS). In an effort to identify as many possible discrepancies as possible for further inspection, the -level for all statistical tests comparing IMM predictions to observed data will be set to 0.1. This less stringent criterion, along with the multiple testing being conducted, should detect all perceived differences including many false positive signals resulting from random variation. The results of these analyses will reveal areas of the model requiring adjustment to improve overall IMM output, which will thereby provide better decision support for mission critical applications.

Extrapolation of vertical target motion through a brief visual occlusion.

PubMed

Zago, Myrka; Iosa, Marco; Maffei, Vincenzo; Lacquaniti, Francesco

2010-03-01

It is known that arbitrary target accelerations along the horizontal generally are extrapolated much less accurately than target speed through a visual occlusion. The extent to which vertical accelerations can be extrapolated through an occlusion is much less understood. Here, we presented a virtual target rapidly descending on a blank screen with different motion laws. The target accelerated under gravity (1g), decelerated under reversed gravity (-1g), or moved at constant speed (0g). Probability of each type of acceleration differed across experiments: one acceleration at a time, or two to three different accelerations randomly intermingled could be presented. After a given viewing period, the target disappeared for a brief, variable period until arrival (occluded trials) or it remained visible throughout (visible trials). Subjects were asked to press a button when the target arrived at destination. We found that, in visible trials, the average performance with 1g targets could be better or worse than that with 0g targets depending on the acceleration probability, and both were always superior to the performance with -1g targets. By contrast, the average performance with 1g targets was always superior to that with 0g and -1g targets in occluded trials. Moreover, the response times of 1g trials tended to approach the ideal value with practice in occluded protocols. To gain insight into the mechanisms of extrapolation, we modeled the response timing based on different types of threshold models. We found that occlusion was accompanied by an adaptation of model parameters (threshold time and central processing time) in a direction that suggests a strategy oriented to the interception of 1g targets at the expense of the interception of the other types of tested targets. We argue that the prediction of occluded vertical motion may incorporate an expectation of gravity effects.

Estimating correlation between multivariate longitudinal data in the presence of heterogeneity.

PubMed

Gao, Feng; Philip Miller, J; Xiong, Chengjie; Luo, Jingqin; Beiser, Julia A; Chen, Ling; Gordon, Mae O

2017-08-17

Estimating correlation coefficients among outcomes is one of the most important analytical tasks in epidemiological and clinical research. Availability of multivariate longitudinal data presents a unique opportunity to assess joint evolution of outcomes over time. Bivariate linear mixed model (BLMM) provides a versatile tool with regard to assessing correlation. However, BLMMs often assume that all individuals are drawn from a single homogenous population where the individual trajectories are distributed smoothly around population average. Using longitudinal mean deviation (MD) and visual acuity (VA) from the Ocular Hypertension Treatment Study (OHTS), we demonstrated strategies to better understand the correlation between multivariate longitudinal data in the presence of potential heterogeneity. Conditional correlation (i.e., marginal correlation given random effects) was calculated to describe how the association between longitudinal outcomes evolved over time within specific subpopulation. The impact of heterogeneity on correlation was also assessed by simulated data. There was a significant positive correlation in both random intercepts (ρ = 0.278, 95% CI: 0.121-0.420) and random slopes (ρ = 0.579, 95% CI: 0.349-0.810) between longitudinal MD and VA, and the strength of correlation constantly increased over time. However, conditional correlation and simulation studies revealed that the correlation was induced primarily by participants with rapid deteriorating MD who only accounted for a small fraction of total samples. Conditional correlation given random effects provides a robust estimate to describe the correlation between multivariate longitudinal data in the presence of unobserved heterogeneity (NCT00000125).

Quantifying dominance of intra-storm phase of interception process by small isolated canopies

NASA Astrophysics Data System (ADS)

Yerk, Walter; Montalto, Franco

2014-05-01

Precipitation interception by vegetation canopies has long been recognized as a major component of the hydrologic cycle; however, historically most research has been dedicated to closed or sparse canopy forests. The goal of our research was to quantify rainfall partitioning by small isolated canopies in an urban setting. The field experiment involved small forms of four shrub species (Prunus laurocerasus, Cornus sericea, Itea virginica and Hydrangea quercifolia) with crown heights 40 - 80 cm and diameters 35 - 60 cm. Each plant had ten rain gauges to measure throughfall with a sampling frequency of 5 seconds. An on-site automated weather station provided meteorological data. Leaf area index (LAI) was measured by manual counting. We estimated the canopy storage capacities of all four species to be less than 0.5 mm. The obtained data showed statistically significant differences in interception properties among all four species, except between Cornus and Itea. Cumulative interception loss for the period of August-December 2013 was 10% for Cornus, 16% for Itea, 29% for Hydrangea, and 49% for Prunus. The observations revealed a weak relationship between interception abilities and LAI for all four species. Throughfall and precipitation intensities (mm/hr) expressed very strong linear relationship (adjusted coefficients of determination were from 0.80 to 0.95) for the entire range of observed rainfall intensities. For Cornus the ratio of throughfall to precipitation intensity was close to 0.93:1, for Itea it was 0.82:1. The ratios were lesser for Hydrangea (0.65:1), and especially for Prunus (0.48:1). Therefore we show that reduced by the canopy, throughfall intensity results in the bulk of precipitation depth intercepted during the rain events. In contrast, the amount of water stored on the canopy and evaporated between and after rain events contributes minimally to interception. Simulations of potential evaporation based on the Penman-Monteith method showed a large underestimation of evaporation from the wet canopies during the rain events. Approaches other than energy balance models of potential evaporation from a still water surface are being discussed in order to explain large evaporation from within a wet isolated canopy.

Biomechanical factors contributing to self-organization in seagrass landscapes

USGS Publications Warehouse

Fonseca, M.S.; Koehl, M.A.R.; Kopp, B.S.

2007-01-01

Field observations have revealed that when water flow is consistently from one direction, seagrass shoots align in rows perpendicular to the primary axis of flow direction. In this study, live Zostera marina shoots were arranged either randomly or in rows perpendicular to the flow direction and tested in a seawater flume under unidirectional flow and waves to determine if shoot arrangement: a) influenced flow-induced force on individual shoots, b) differentially altered water flow through the canopy, and c) influenced light interception by the canopy. In addition, blade breaking strength was compared with flow-induced force to determine if changes in shoot arrangement might reduce the potential for damage to shoots. Under unidirectional flow, both current velocity in the canopy and force on shoots were significantly decreased when shoots were arranged in rows as compared to randomly. However, force on shoots was nearly constant with downstream distance, arising from the trade-off of shoot bending and in-canopy flow reduction. The coefficient of drag was higher for randomly-arranged shoots at low velocities (< 30 cm s- 1) but converged rapidly among the two shoot arrangements at higher velocities. Shoots arranged in rows tended to intercept slightly more light than those arranged randomly. Effects of shoot arrangement under waves were less clear, potentially because we did not achieve the proper plant size?row spacing ratio. At this point, we may only suggest that water motion, as opposed to light capture, is the dominant physical mechanism responsible for these shoot arrangements. Following a computation of the Environmental Stress Factor, we concluded that even photosynthetically active blades may be damaged or broken under frequently encountered storm conditions, irrespective of shoot arrangement. We hypothesize that when flow is generally from one direction, seagrass bed patterns over multiple scales of consideration may arise as a cumulative effect of individual shoot self-organization driven by reduced force and drag on the shoots and somewhat improved light capture.

Velocity control as a tool for optimal plume containment in the Equus Beds aquifer, Kansas

USGS Publications Warehouse

Heidari, M.; Sadeghipour, J.; Drici, O.

1987-01-01

A ground-water-management model was developed to investigate the best management options for the containment of an oil-field-brine plume in the Equus Beds aquifer in south-central Kansas. The main purpose of the management model was to find the optimal locations and minimum rates of pumpage of a set of plume-interception wells, to successfully reverse the velocity vectors at observation wells located along the plume front, and also to satisfy freshwater demands from supply wells. The effects of the calculated minimum withdrawals from the interception wells on the migration of contaminants throughout the ground-water system were evaluated utilizing a solute-transport model. This latter analysis was carried out to ensure the containment of the plume. Whereas application of the management model to the study area achieves the management objectives, the implementation of the results is believed to be impractical and expensive.

Long-term effects of adolescent marijuana use prevention on adult mental health services utilization: the midwestern prevention project.

PubMed

Riggs, Nathaniel R; Pentz, Mary Ann

2009-01-01

Evaluated were effects of a drug abuse(1) prevention program, previously shown to prevent marijuana use in adolescence, on adulthood mental health service use. Analyses were conducted on 961 6th (41%) and 7th (59%) grade participants randomly assigned to intervention or control groups at baseline in 1984. These participants were followed-up through 2003 representing 15 waves of data collection. Eighty-five percent of participants were Caucasian and 56% were female. The hypothesis was that direct program effects on early adulthood mental health service use would be mediated by program effects on high school marijuana use trajectories. Structural equation models, imputing for missing data, demonstrated that MPP (Midwestern Prevention Project) program effects on mental health were mediated by the marijuana use growth curve intercept. Findings support the role of early adolescent drug use prevention programs in impacting later mental health problems. The study's limitations are noted.

Estimation of the time since death--reconsidering the re-establishment of rigor mortis.

PubMed

Anders, Sven; Kunz, Michaela; Gehl, Axel; Sehner, Susanne; Raupach, Tobias; Beck-Bornholdt, Hans-Peter

2013-01-01

In forensic medicine, there is an undefined data background for the phenomenon of re-establishment of rigor mortis after mechanical loosening, a method used in establishing time since death in forensic casework that is thought to occur up to 8 h post-mortem. Nevertheless, the method is widely described in textbooks on forensic medicine. We examined 314 joints (elbow and knee) of 79 deceased at defined time points up to 21 h post-mortem (hpm). Data were analysed using a random intercept model. Here, we show that re-establishment occurred in 38.5% of joints at 7.5 to 19 hpm. Therefore, the maximum time span for the re-establishment of rigor mortis appears to be 2.5-fold longer than thought so far. These findings have major impact on the estimation of time since death in forensic casework.

Hair mercury concentrations and in vitro fertilization (IVF) outcomes among women from a fertility clinic.

PubMed

Wright, Diane L; Afeiche, Myriam C; Ehrlich, Shelley; Smith, Kristen; Williams, Paige L; Chavarro, Jorge E; Batsis, Maria; Toth, Thomas L; Hauser, Russ

2015-01-01

Total hair mercury (Hg) was measured among 205 women undergoing in vitro fertilization (IVF) treatment and the association with prospectively collected IVF outcomes (229 IVF cycles) was evaluated. Hair Hg levels (median=0.62ppm, range: 0.03-5.66ppm) correlated with fish intake (r=0.59), and exceeded the recommended EPA reference of 1ppm in 33% of women. Generalized linear mixed models with random intercepts accounting for within-woman correlations across treatment cycles were used to evaluate the association of hair Hg with IVF outcomes adjusted for age, body mass index, race, smoking status, infertility diagnosis, and protocol type. Hair Hg levels were not related to ovarian stimulation outcomes (peak estradiol levels, total and mature oocyte yields) or to fertilization rate, embryo quality, clinical pregnancy rate or live birth rate. Copyright © 2015 Elsevier Inc. All rights reserved.

Self-reported mobile phone use and semen parameters among men from a fertility clinic.

PubMed

Lewis, Ryan C; Mínguez-Alarcón, Lidia; Meeker, John D; Williams, Paige L; Mezei, Gabor; Ford, Jennifer B; Hauser, Russ

2017-01-01

There is increasing concern that use of mobile phones, a source of low-level radio-frequency electromagnetic fields, may be associated with poor semen quality, but the epidemiologic evidence is limited and conflicting. The relationship between mobile phone use patterns and markers of semen quality was explored in a longitudinal cohort study of 153 men that attended an academic fertility clinic in Boston, Massachusetts. Information on mobile phone use duration, headset or earpiece use, and the body location in which the mobile phone was carried was ascertained via nurse-administered questionnaire. Semen samples (n=350) were collected and analyzed onsite. To account for multiple semen samples per man, linear mixed models with random intercepts were used to investigate the association between mobile phone use and semen parameters. Overall, there was no evidence for a relationship between mobile phone use and semen quality. Copyright © 2016 Elsevier Inc. All rights reserved.

Self-reported mobile phone use and semen parameters among men from a fertility clinic

PubMed Central

Lewis, Ryan C.; Mínguez-Alarcón, Lidia; Meeker, John D.; Williams, Paige L.; Mezei, Gabor; Ford, Jennifer B.; Hauser, Russ

2017-01-01

There is increasing concern that use of mobile phones, a source of low-level radio-frequency electromagnetic fields, may be associated with poor semen quality, but the epidemiologic evidence is limited and conflicting. The relationship between mobile phone use patterns and markers of semen quality was explored in a longitudinal cohort study of 153 men that attended an academic fertility clinic in Boston, Massachusetts. Information on mobile phone use duration, headset or earpiece use, and the body location in which the mobile phone was carried was ascertained via nurse-administered questionnaire. Semen samples (n=350) were collected and analyzed onsite. To account for multiple semen samples per man, linear mixed models with random intercepts were used to investigate the association between mobile phone use and semen parameters. Overall, there was no evidence for a relationship between mobile phone use and semen quality. PMID:27838386

Geographic and temporal validity of prediction models: Different approaches were useful to examine model performance

PubMed Central

Austin, Peter C.; van Klaveren, David; Vergouwe, Yvonne; Nieboer, Daan; Lee, Douglas S.; Steyerberg, Ewout W.

2017-01-01

Objective Validation of clinical prediction models traditionally refers to the assessment of model performance in new patients. We studied different approaches to geographic and temporal validation in the setting of multicenter data from two time periods. Study Design and Setting We illustrated different analytic methods for validation using a sample of 14,857 patients hospitalized with heart failure at 90 hospitals in two distinct time periods. Bootstrap resampling was used to assess internal validity. Meta-analytic methods were used to assess geographic transportability. Each hospital was used once as a validation sample, with the remaining hospitals used for model derivation. Hospital-specific estimates of discrimination (c-statistic) and calibration (calibration intercepts and slopes) were pooled using random effects meta-analysis methods. I2 statistics and prediction interval width quantified geographic transportability. Temporal transportability was assessed using patients from the earlier period for model derivation and patients from the later period for model validation. Results Estimates of reproducibility, pooled hospital-specific performance, and temporal transportability were on average very similar, with c-statistics of 0.75. Between-hospital variation was moderate according to I2 statistics and prediction intervals for c-statistics. Conclusion This study illustrates how performance of prediction models can be assessed in settings with multicenter data at different time periods. PMID:27262237

Eye movements in interception with delayed visual feedback.

PubMed

Cámara, Clara; de la Malla, Cristina; López-Moliner, Joan; Brenner, Eli

2018-07-01

The increased reliance on electronic devices such as smartphones in our everyday life exposes us to various delays between our actions and their consequences. Whereas it is known that people can adapt to such delays, the mechanisms underlying such adaptation remain unclear. To better understand these mechanisms, the current study explored the role of eye movements in interception with delayed visual feedback. In two experiments, eye movements were recorded as participants tried to intercept a moving target with their unseen finger while receiving delayed visual feedback about their own movement. In Experiment 1, the target randomly moved in one of two different directions at one of two different velocities. The delay between the participant's finger movement and movement of the cursor that provided feedback about the finger movements was gradually increased. Despite the delay, participants followed the target with their gaze. They were quite successful at hitting the target with the cursor. Thus, they moved their finger to a position that was ahead of where they were looking. Removing the feedback showed that participants had adapted to the delay. In Experiment 2, the target always moved in the same direction and at the same velocity, while the cursor's delay varied across trials. Participants still always directed their gaze at the target. They adjusted their movement to the delay on each trial, often succeeding to intercept the target with the cursor. Since their gaze was always directed at the target, and they could not know the delay until the cursor started moving, participants must have been using peripheral vision of the delayed cursor to guide it to the target. Thus, people deal with delays by directing their gaze at the target and using both experience from previous trials (Experiment 1) and peripheral visual information (Experiment 2) to guide their finger in a way that will make the cursor hit the target.

Motivational Enhancement for Increasing Adherence to CPAP: A Randomized Controlled Trial.

PubMed

Bakker, Jessie P; Wang, Rui; Weng, Jia; Aloia, Mark S; Toth, Claudia; Morrical, Michael G; Gleason, Kevin J; Rueschman, Michael; Dorsey, Cynthia; Patel, Sanjay R; Ware, James H; Mittleman, Murray A; Redline, Susan

2016-08-01

Motivational enhancement (ME) shows promise as a means of increasing adherence to CPAP for OSA. We performed an open-label, parallel-arm, randomized controlled trial of CPAP only or CPAP + ME, recruiting individuals 45 to 75 years with moderate or severe OSA without marked sleepiness and with either established cardiovascular disease (CVD) or at risk for CVD. All participants received standardized CPAP support from a sleep technologist; those randomly assigned to CPAP + ME also received standardized ME delivered by a psychologist during two appointments and six phone calls over 32 weeks. Mixed-effect models with subject-specific intercepts and slopes were fitted to compare objective CPAP adherence between arms, adjusting for follow-up duration, randomization factors, and device manufacturer. All analyses were intention-to-treat. Overall, 83 participants (n = 42 CPAP only; n = 41 CPAP + ME) contributed 14,273 nights of data for 6 months. Participants were predominantly male (67%) and had a mean ± SD age of 63.9 ± 7.4 years, a BMI of 31.1 ± 5.2 kg/m(2), and an apnea-hypopnea index of 26.2 ± 12.9 events/h. In our fully adjusted model, average nightly adherence for 6 months was 99.0 min/night higher with CPAP + ME compared with CPAP only (P = .003; primary analysis). A subset of 52 participants remained in the study for 12 months; modeling these data yielded a consistent difference in adherence between arms of 97 min/night (P = .006) favoring CPAP + ME. ME delivered during brief appointments and phone calls resulted in a clinically significant increase in CPAP adherence. This strategy may represent a feasible approach for optimizing management of OSA. ClinicalTrials.gov; No.: NCT01261390; URL: www.clinicaltrials.gov. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Calculation of intercepted runoff depth based on stormwater quality and environmental capacity of receiving waters for initial stormwater pollution management.

PubMed

Peng, Hai-Qin; Liu, Yan; Gao, Xue-Long; Wang, Hong-Wu; Chen, Yi; Cai, Hui-Yi

2017-11-01

While point source pollutions have gradually been controlled in recent years, the non-point source pollution problem has become increasingly prominent. The receiving waters are frequently polluted by the initial stormwater from the separate stormwater system and the wastewater from sewage pipes through stormwater pipes. Consequently, calculating the intercepted runoff depth has become a problem that must be resolved immediately for initial stormwater pollution management. The accurate calculation of intercepted runoff depth provides a solid foundation for selecting the appropriate size of intercepting facilities in drainage and interception projects. This study establishes a separate stormwater system for the Yishan Building watershed of Fuzhou City using the InfoWorks Integrated Catchment Management (InfoWorks ICM), which can predict the stormwater flow velocity and the flow of discharge outlet after each rainfall. The intercepted runoff depth is calculated from the stormwater quality and environmental capacity of the receiving waters. The average intercepted runoff depth from six rainfall events is calculated as 4.1 mm based on stormwater quality. The average intercepted runoff depth from six rainfall events is calculated as 4.4 mm based on the environmental capacity of the receiving waters. The intercepted runoff depth differs when calculated from various aspects. The selection of the intercepted runoff depth depends on the goal of water quality control, the self-purification capacity of the water bodies, and other factors of the region.

Understanding the Dynamics of Soil Carbon in CMIP5 Models

NASA Astrophysics Data System (ADS)

Todd-Brown, K. E.; Luo, Y.; Randerson, J. T.; Allison, S. D.; Smith, M. J.

2014-12-01

Soil carbon stocks have the potential to be a strong source or sink for carbon dioxide over the next century, playing a critical role in climate change. These stocks are the result of small differences between much larger primary carbon fluxes: gross primary production, litter fall, autotrophic respiration and heterotrophic respiration. There was little agreement on predicted soil carbon stocks between Earth system models (ESMs) in the most recent Climate Model Intercomparison Project. Predicted present-day stocks ranged from roughly 500 Pg to over 3000 Pg and predicted changes over the 21st century ranged from -70 Pg to +250 Pg). The primary goal of this study was to understand why such large differences exist. We constructed four reduced complexity models to describe the primary carbon fluxes, making different assumptions about how soil carbon fluxes are modelled in ESMs. For each of these reduced complexity models we statistically inferred the most likely model parameters given the gridded ESM simulation outputs. Gross primary production was best explained by incoming short wave radiation, CO2 concentration, and leaf area index (global GPP comparison of simulation vs reduced complexity model of R2>0.9 (p < 1e-4) with slopes between 0.65 and 1.2 and intercepts between -13 and 67 Pg C yr-1). Autotrophic respiration was best explained as a proportion of GPP (R2 > 0.9 (p < 1e-4) with slopes between 0.78 and 1.1 and intercepts between -15 and 14 Pg C yr-1). Flux between the vegetation and soil pools were best explained as a proportion of the vegetation carbon stock (R2 > 0.9 (p < 1e-4) with slopes between 0.9 and 2.1 and intercepts between -65 and 25 Pg C yr-1). Finally heterotrophic respiration was best explained as a function of soil carbon stocks and soil temperature (R2 > 0.9 (p < 1e-4) with slopes between 0.7 and 1.5 and intercepts between -40 and 15 Pg C yr-1). This research suggests three main lines of decomposition model improvement: 1) improve connecting sub-models, 2) data integration to improve parameterization, 3) modification of model structure. The implied variation in RCM parameterization suggests that data integration could constrain model simulation results. However, the similarity in model structure may lead to systematic biases in the simulations without the introduction of new model structures.

Back-stepping active disturbance rejection control design for integrated missile guidance and control system via reduced-order ESO.

PubMed

Xingling, Shao; Honglun, Wang

2015-07-01

This paper proposes a novel composite integrated guidance and control (IGC) law for missile intercepting against unknown maneuvering target with multiple uncertainties and control constraint. First, by using back-stepping technique, the proposed IGC law design is separated into guidance loop and control loop. The unknown target maneuvers and variations of aerodynamics parameters in guidance and control loop are viewed as uncertainties, which are estimated and compensated by designed model-assisted reduced-order extended state observer (ESO). Second, based on the principle of active disturbance rejection control (ADRC), enhanced feedback linearization (FL) based control law is implemented for the IGC model using the estimates generated by reduced-order ESO. In addition, performance analysis and comparisons between ESO and reduced-order ESO are examined. Nonlinear tracking differentiator is employed to construct the derivative of virtual control command in the control loop. Third, the closed-loop stability for the considered system is established. Finally, the effectiveness of the proposed IGC law in enhanced interception performance such as smooth interception course, improved robustness against multiple uncertainties as well as reduced control consumption during initial phase are demonstrated through simulations. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Negligible impact of differential item functioning between Black and White dialysis patients on the Kidney Disease Quality of Life 36-item short form survey (KDQOLTM-36).

PubMed

Peipert, John D; Bentler, Peter; Klicko, Kristi; Hays, Ron D

2018-05-14

Black dialysis patients report better health-related quality of life (HRQOL) than White patients, which may be explained if Black and White patients respond systematically differently to HRQOL survey items. We examined differential item functioning (DIF) of the Kidney Disease Quality of Life 36-item (KDQOL TM -36) Burden of Kidney Disease, Symptoms and Problems with Kidney Disease, and Effects of Kidney Disease scales between Black (n = 18,404) and White (n = 21,439) dialysis patients. We fit multiple group confirmatory factor analysis models with increasing invariance: a Configural model (invariant factor structure), a Metric model (invariant factor loadings), and a Scalar model (invariant intercepts). Criteria for invariance included non-significant χ 2 tests, > 0.002 difference in the models' CFI, and > 0.015 difference in RMSEA and SRMR. Next, starting with a fully invariant model, we freed loadings and intercepts item-by-item to determine if DIF impacted estimated KDQOL TM -36 scale means. ΔCFI was 0.006 between the metric and scalar models but was reduced to 0.001 when we freed intercepts for the burdens and symptoms and problems of kidney disease scales. In comparison to standardized means of 0 in the White group, those for the Black group on the Burdens, Symptoms and Problems, and Effects of Kidney Disease scales were 0.218, 0.061, and 0.161, respectively. When loadings and thresholds were released sequentially, differences in means between models ranged between 0.001 and 0.048. Despite some DIF, impacts on KDQOL TM -36 responses appear to be minimal. We conclude that the KDQOL TM -36 is appropriate to make substantive comparisons of HRQOL between Black and White dialysis patients.

Implication of Intrastorm Rainfall-Canopy Interaction on Interception Performance of Broadleaf Evergreen Shrubs in Urban Setting

NASA Astrophysics Data System (ADS)

Yerk, W.; Montalto, F. A.

2014-12-01

Because of its ability to intercept a portion of rainfall, vegetated canopy has a significant influence on the urban hydrological cycle. In turn, urban watersheds, characterized by large impervious areas, have an enormous and often adverse impact on receiving waters. However, most historical interception research has been dedicated to forest canopies. The goal of our research was to quantify rainfall partitioning by isolated evergreen canopies in an urban setting. Two years of the field experiment involved three exemplars of Cherry Laurel (Prunus laurocerasus'Otto Luyken'.) Each plant had ten rain gauges to measure throughfall with a five second sampling frequency. A number of preventive techniques were introduced to minimize the gauges' errors (e.g., splash-in, splash-out and excessive wetting.) Leaf area index was measured manually. We estimated the canopy storage capacity to be less than 0.5 mm. An on-site automated weather station provided meteorological data. Cumulative interception loss for the periods of August-December 2013 and April-July 2014 was 51%. Phenological change did not show a stable pattern of influence on throughfall depths. Measurements in May and July 2014 showed a high variability of stemflow (2-16%) between rain events. Throughfall and precipitation intensities (mm/hr) expressed strong linear relationships (adjusted coefficient of determination R20.79) for the entire range of observed rainfall intensities. The ratio of throughfall to precipitation intensity was 0.49:1. The observations suggest that reduction of throughfall intensity by the canopy during a rainstorm determines the bulk of interception depth. In contrast, the amount of water stored on the canopy and evaporated between and after rain events contributes minimally to interception. Simulations of potential evaporation based on the Penman-Monteith method revealed a serious underestimation of evaporation from the wet canopy surfaces during the rain events. Mechanisms other than heat balance models of potential evaporation from a still water surface are being discussed in order to explain large intrastorm evaporation from within an isolated canopy.

Biological monitoring of environmental quality: The use of developmental instability

USGS Publications Warehouse

Freeman, D.C.; Emlen, J.M.; Graham, J.H.; Hough, R. A.; Bannon, T.A.

1994-01-01

Distributed robustness is thought to influence the buffering of random phenotypic variation through the scale-free topology of gene regulatory, metabolic, and protein-protein interaction networks. If this hypothesis is true, then the phenotypic response to the perturbation of particular nodes in such a network should be proportional to the number of links those nodes make with neighboring nodes. This suggests a probability distribution approximating an inverse power-law of random phenotypic variation. Zero phenotypic variation, however, is impossible, because random molecular and cellular processes are essential to normal development. Consequently, a more realistic distribution should have a y-intercept close to zero in the lower tail, a mode greater than zero, and a long (fat) upper tail. The double Pareto-lognormal (DPLN) distribution is an ideal candidate distribution. It consists of a mixture of a lognormal body and upper and lower power-law tails.

Measurement and modelling of rainfall interception by tropical secondary forests in upland Eastern Madagascar

NASA Astrophysics Data System (ADS)

Prasad Ghimire, Chandra; van Meerveld, Ilja H. J.; Zwartendijk, Bob W.; Ravelona, Maafaka; Lahitiana, Jaona; Lubczynski, Maciek W.; Bruijnzeel, L. Adrian

2016-04-01

Secondary forests occupy a larger area than old-growth forest in many tropical regions but their hydrological functioning is still poorly understood. As part of a larger venture investigating the "trade-off" between the possibly strongly enhanced water use of vigorously regenerating secondary forest versus likely improved infiltration compared to degraded grassland (baseline situation) in Eastern Madagascar, this presentation reports on a comparison of measured and modelled canopy interception losses for a mature (ca. 20 years; basal area BA 35.5 m2 ha-1, LAI 3.39) and a young (5-7 years; BA 6.3 m2 ha-1, LAI 1.83) secondary forest. Measurements of gross rainfall (P), throughfall (TF) and stemflow (SF) were made in both forests over a one-year period (October 2014-September 2015). Interception losses (I) from the two forests were also simulated using the revised analytical model of Gash et al. (1995), representing a first for tropical secondary forest. Overall measured TF, SF and derived I in the mature secondary forest were 71.0%, 1.7% and 27.3% of incident P, respectively. Corresponding values for the young secondary forest were 75.8%, 6.2% and 18.0%. The high SF found for the latter forest reflects the strongly upward thrusting habit of the branches of the dominant species (Psiadia altissima) which favours funneling of incident P. The presently found I for the mature forest is similar to that reported for other tropical montane rainforests not affected by fog but that for the younger forest is higher than reported for similarly aged lowland forests. These findings can be explained by the prevailing low rainfall intensities and frequent occurrence of small rainfall events (~70% < 5 mm). The Gash model was able to reproduce measured cumulative I at both sites accurately and succeeded in capturing the variability in I associated with seasonal variability in rainfall characteristics, provided the TF-based value for wet-canopy evaporation rate was used instead of that based on the Penman-Monteith equation. Key words: Secondary tropical forest, Stemflow, Throughfall, Gash's analytical interception model

Health service costs in Europe: cost and reimbursement of primary hip replacement in nine countries.

PubMed

Stargardt, Tom

2008-01-01

This paper assesses variations in the cost of primary hip replacement between and within nine member states of the European Union (EU). It also compares the cost of service with public-payer reimbursements. To do so, data on cost and reimbursement were surveyed at the micro-level in 42 hospitals in Denmark, England, France, Germany, Hungary, Italy, The Netherlands, Poland, and Spain. The total cost of treatment ranged from 1290 euros (Hungary) to 8739 euros (The Netherlands), with a mean cost of 5043 euros (STD +/- 2071 euros). The main cost drivers were found to be implants (34% of total cost on average) and ward costs (20.9% of total cost on average). A one-way random effects analysis of variance model indicated that 74.0% of variation was between and only 26% of variation was within countries. In a two-level random-intercept regression model, purchasing-power parities explained 79.4% of the explainable between-country variation, while the percentage of uncemented implants used and the number of beds explained 12.1 and 1.6% of explainable within-country variation, respectively. The large differences in cost and reimbursement between Poland, Hungary, and the other EU member states shows that primary total hip replacement is a highly relevant case for cross-border care. Copyright 2008 John Wiley & Sons, Ltd.

a Comparison Between Two Ols-Based Approaches to Estimating Urban Multifractal Parameters

NASA Astrophysics Data System (ADS)

Huang, Lin-Shan; Chen, Yan-Guang

Multifractal theory provides a new spatial analytical tool for urban studies, but many basic problems remain to be solved. Among various pending issues, the most significant one is how to obtain proper multifractal dimension spectrums. If an algorithm is improperly used, the parameter spectrums will be abnormal. This paper is devoted to investigating two ordinary least squares (OLS)-based approaches for estimating urban multifractal parameters. Using empirical study and comparative analysis, we demonstrate how to utilize the adequate linear regression to calculate multifractal parameters. The OLS regression analysis has two different approaches. One is that the intercept is fixed to zero, and the other is that the intercept is not limited. The results of comparative study show that the zero-intercept regression yields proper multifractal parameter spectrums within certain scale range of moment order, while the common regression method often leads to abnormal multifractal parameter values. A conclusion can be reached that fixing the intercept to zero is a more advisable regression method for multifractal parameters estimation, and the shapes of spectral curves and value ranges of fractal parameters can be employed to diagnose urban problems. This research is helpful for scientists to understand multifractal models and apply a more reasonable technique to multifractal parameter calculations.

Aerial surveys adjusted by ground surveys to estimate area occupied by black-tailed prairie dog colonies

USGS Publications Warehouse

Sidle, John G.; Augustine, David J.; Johnson, Douglas H.; Miller, Sterling D.; Cully, Jack F.; Reading, Richard P.

2012-01-01

Aerial surveys using line-intercept methods are one approach to estimate the extent of prairie dog colonies in a large geographic area. Although black-tailed prairie dogs (Cynomys ludovicianus) construct conspicuous mounds at burrow openings, aerial observers have difficulty discriminating between areas with burrows occupied by prairie dogs (colonies) versus areas of uninhabited burrows (uninhabited colony sites). Consequently, aerial line-intercept surveys may overestimate prairie dog colony extent unless adjusted by an on-the-ground inspection of a sample of intercepts. We compared aerial line-intercept surveys conducted over 2 National Grasslands in Colorado, USA, with independent ground-mapping of known black-tailed prairie dog colonies. Aerial line-intercepts adjusted by ground surveys using a single activity category adjustment overestimated colonies by ≥94% on the Comanche National Grassland and ≥58% on the Pawnee National Grassland. We present a ground-survey technique that involves 1) visiting on the ground a subset of aerial intercepts classified as occupied colonies plus a subset of intercepts classified as uninhabited colony sites, and 2) based on these ground observations, recording the proportion of each aerial intercept that intersects a colony and the proportion that intersects an uninhabited colony site. Where line-intercept techniques are applied to aerial surveys or remotely sensed imagery, this method can provide more accurate estimates of black-tailed prairie dog abundance and trends

Transport of intercepted snow from trees during snow storms

Treesearch

David H. Miller

1966-01-01

Five principal processes by which intercepted snow in trees is removed during snow storms are described and evaluated as far as data permit: vapor flux from melt water, vapor flux from bodies of snow, stem flow and dripping of melt water, sliding of bodies of intercepted snow from branches, and wind erosion and transport of intercepted snow. Further research is...

First-Episode Psychosis and the Criminal Justice System: Using a Sequential Intercept Framework to Highlight Risks and Opportunities.

PubMed

Wasser, Tobias; Pollard, Jessica; Fisk, Deborah; Srihari, Vinod

2017-10-01

In first-episode psychosis there is a heightened risk of aggression and subsequent criminal justice involvement. This column reviews the evidence pointing to these heightened risks and highlights opportunities, using a sequential intercept model, for collaboration between mental health services and existing diversionary programs, particularly for patients whose behavior has already brought them to the attention of the criminal justice system. Coordinating efforts in these areas across criminal justice and clinical spheres can decrease the caseload burden on the criminal justice system and optimize clinical and legal outcomes for this population.

The significance of the interception in a Thornthwaite-type monthly step water balance model in context of the climate change

NASA Astrophysics Data System (ADS)

Herceg, András; Kalicz, Péter; Kisfaludi, Balázs

2017-04-01

The hydrological impacts of the climate change can be dramatic. Our main purpose is the methodical improvement of a previously established Thornthwaite-type monthly step water balance model, which takes the interception item into account, and compare the results of the evapotranspiration and the soil moisture projections for the 21st century of the original and the upgraded models. Both of the models will be calibrated and validated (using remote-sensed actual evapotranspiration data, called CREMAP) and requires only temperature and precipitation time series as inputs. The projections based on 4 bias-corrected regional climate models databases (FORESEE), and the 3 investigation periods are: 2015-2045, 2045-2075, and 2070-2100. The key parameter is the water storage capacity of the soil, which can be also calibrated using the actual evapotranspiration data. The maximal rooting depth is determinable if the physical properties of the soil are available. The interception can be ranges from 5-40% of gross precipitation, which rate are differing in the various plant communities. Generally, the forests canopy intercepts considerable amounts of rainfall and evaporates back into the atmosphere during and after precipitation event. Leaf area index (LAI) is one of the most significant factor, which determine the canopies storage capacity. Here, MODIS sensor based LAI time series are applied to estimate the storage capacity. A forest covered experimental catchment is utilized for testing the models near to Sopron, Hungary. The projections will expected to demonstrate increasing actual evapotranspiration values, but decreasing trends for the 10 percentile minimum soil moisture values at the end of the 21st century in both model runs. The seasonal periodicity of evapotranspiration may demonstrates the maximums in June or July, while in case of the soil moisture it may shows minimum values in autumn. With the comparison of the two model runs, we expect lower soil water storage capacity (SOILMAX) values for the upgraded model and for that very reason lower soil moisture reservoir as well. Consequently, we will possess a more reliable model, which represents a closer approximation of the reality. The water stress analysis (relative extractable water and soil water deficit) may indicate that more significant water stress assumed to occur in case of the upgraded model run during the 21st century. This research has been supported by the Agroclimate.2 VKSZ_12-1-2013-0034 project, and the second author's work was also supported by the János Bolyai Scholarship of the Hungarian Academy of Sciences.

Genetic parameters for stayability to consecutive calvings in Zebu cattle.

PubMed

Silva, D O; Santana, M L; Ayres, D R; Menezes, G R O; Silva, L O C; Nobre, P R C; Pereira, R J

2017-12-22

Longer-lived cows tend to be more profitable and the stayability trait is a selection criterion correlated to longevity. An alternative to the traditional approach to evaluate stayability is its definition based on consecutive calvings, whose main advantage is the more accurate evaluation of young bulls. However, no study using this alternative approach has been conducted for Zebu breeds. Therefore, the objective of this study was to compare linear random regression models to fit stayability to consecutive calvings of Guzerá, Nelore and Tabapuã cows and to estimate genetic parameters for this trait in the respective breeds. Data up to the eighth calving were used. The models included the fixed effects of age at first calving and year-season of birth of the cow and the random effects of contemporary group, additive genetic, permanent environmental and residual. Random regressions were modeled by orthogonal Legendre polynomials of order 1 to 4 (2 to 5 coefficients) for contemporary group, additive genetic and permanent environmental effects. Using Deviance Information Criterion as the selection criterion, the model with 4 regression coefficients for each effect was the most adequate for the Nelore and Tabapuã breeds and the model with 5 coefficients is recommended for the Guzerá breed. For Guzerá, heritabilities ranged from 0.05 to 0.08, showing a quadratic trend with a peak between the fourth and sixth calving. For the Nelore and Tabapuã breeds, the estimates ranged from 0.03 to 0.07 and from 0.03 to 0.08, respectively, and increased with increasing calving number. The additive genetic correlations exhibited a similar trend among breeds and were higher for stayability between closer calvings. Even between more distant calvings (second v. eighth), stayability showed a moderate to high genetic correlation, which was 0.77, 0.57 and 0.79 for the Guzerá, Nelore and Tabapuã breeds, respectively. For Guzerá, when the models with 4 or 5 regression coefficients were compared, the rank correlations between predicted breeding values for the intercept were always higher than 0.99, indicating the possibility of practical application of the least parameterized model. In conclusion, the model with 4 random regression coefficients is recommended for the genetic evaluation of stayability to consecutive calvings in Zebu cattle.

Intercept Centering and Time Coding in Latent Difference Score Models

ERIC Educational Resources Information Center

Grimm, Kevin J.

2012-01-01

Latent difference score (LDS) models combine benefits derived from autoregressive and latent growth curve models allowing for time-dependent influences and systematic change. The specification and descriptions of LDS models include an initial level of ability or trait plus an accumulation of changes. A limitation of this specification is that the…

Mediation Analysis in a Latent Growth Curve Modeling Framework

ERIC Educational Resources Information Center

von Soest, Tilmann; Hagtvet, Knut A.

2011-01-01

This article presents several longitudinal mediation models in the framework of latent growth curve modeling and provides a detailed account of how such models can be constructed. Logical and statistical challenges that might arise when such analyses are conducted are also discussed. Specifically, we discuss how the initial status (intercept) and…

When three traits make a line: evolution of phenotypic plasticity and genetic assimilation through linear reaction norms in stochastic environments.

PubMed

Ergon, T; Ergon, R

2017-03-01

Genetic assimilation emerges from selection on phenotypic plasticity. Yet, commonly used quantitative genetics models of linear reaction norms considering intercept and slope as traits do not mimic the full process of genetic assimilation. We argue that intercept-slope reaction norm models are insufficient representations of genetic effects on linear reaction norms and that considering reaction norm intercept as a trait is unfortunate because the definition of this trait relates to a specific environmental value (zero) and confounds genetic effects on reaction norm elevation with genetic effects on environmental perception. Instead, we suggest a model with three traits representing genetic effects that, respectively, (i) are independent of the environment, (ii) alter the sensitivity of the phenotype to the environment and (iii) determine how the organism perceives the environment. The model predicts that, given sufficient additive genetic variation in environmental perception, the environmental value at which reaction norms tend to cross will respond rapidly to selection after an abrupt environmental change, and eventually becomes equal to the new mean environment. This readjustment of the zone of canalization becomes completed without changes in genetic correlations, genetic drift or imposing any fitness costs of maintaining plasticity. The asymptotic evolutionary outcome of this three-trait linear reaction norm generally entails a lower degree of phenotypic plasticity than the two-trait model, and maximum expected fitness does not occur at the mean trait values in the population. © 2016 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.

Using ecological momentary assessment to test the effectiveness of a web-based brief alcohol intervention over time among heavy-drinking students: randomized controlled trial.

PubMed

Voogt, Carmen; Kuntsche, Emmanuel; Kleinjan, Marloes; Poelen, Evelien; Engels, Rutger

2014-01-08

Web-based brief alcohol interventions are effective in reducing alcohol use among students when measured at limited follow-up time points. To date, no studies have tested Web-based brief alcohol intervention effectiveness over time by using a large number of measurements. Testing whether the What Do You Drink (WDYD) Web-based brief alcohol intervention can sustain a reduction in alcohol use among heavy-drinking students aged 18-24 years at 1-, 3-, and 6-month follow-up intervals. A purely Web-based, 2-arm, parallel-group randomized controlled trial applying an ecological momentary assessment approach with 30 weekly measurements was conducted in the Netherlands (2010-2011). Participants were recruited offline and online. A total of 907 participants were randomized into the experimental condition (n=456) including the single-session and fully automated WDYD intervention, or into the control condition (n=451) including assessment only. Weekly alcohol consumption and frequency of binge drinking were the self-assessed outcome measures. Attrition rates of the 907 participants were 110 (12.1%), 130 (14.3%), and 162 (17.9%) at 1-, 3-, and 6-month follow-up intervals, respectively. Latent growth curve analyses according to the intention-to-treat principle revealed that participants in the experimental condition had significantly lower weekly alcohol consumption compared to participants in the control condition that was sustained at 3-month follow-up (intercept=-2.60, P<.001; slope=0.16, P=.08). Additional linear regression analyses indicated that this intercept difference resulted from significantly higher levels of alcohol units per week for participants in the control condition compared to those in the experimental condition at 1-month (beta=-2.56, SE 0.74, Cohen's d=0.20, P=.001), 3-month (beta=-1.76, SE 0.60, Cohen's d=0.13, P=.003), and 6-month (beta=-1.21, SE 0.58, Cohen's d=0.09, P=.04) follow-up intervals. Latent growth curve analyses further indicated that participants in the experimental condition had a significantly lower frequency of binge drinking compared to participants in the control condition that was sustained at 6-month follow-up (intercept=-0.14, P=.01; slope=0.004, P=.19). This intercept difference resulted from higher levels in this outcome for participants in the control condition relative to participants in the experimental condition at 1-month (beta=-1.15, SE 0.06, Cohen's d=0.16, P=.01), 3-month (beta=-0.12, SE 0.05, Cohen's d=0.09, P=.01), and 6-month (beta=-0.09, SE 0.05, Cohen's d=0.03, P=.045) follow-up intervals. The WDYD intervention was shown to be effective in preventing an increase in weekly alcohol consumption and frequency of binge drinking directly after the intervention. This effect was sustained 3 and 6 months after the intervention. Netherlands Trial Register NTR2665; http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2665 (Archived by WebCite at http://webcitation.org/6LuQVn12M).

Midday Depression vs. Midday Peak in Diurnal Light Interception: Contrasting Patterns at Crown and Leaf Scales in a Tropical Evergreen Tree.

PubMed

Ventre-Lespiaucq, Agustina; Flanagan, Nicola S; Ospina-Calderón, Nhora H; Delgado, Juan A; Escudero, Adrián

2018-01-01

Crown architecture usually is heterogeneous as a result of foraging in spatially and temporally heterogeneous light environments. Ecologists are only beginning to identify the importance of temporal heterogeneity for light acquisition in plants, especially at the diurnal scale. Crown architectural heterogeneity often leads to a diurnal variation in light interception. However, maximizing light interception during midday may not be an optimal strategy in environments with excess light. Instead, long-lived plants are expected to show crown architectures and leaf positions that meet the contrasting needs of light interception and avoidance of excess light on a diurnal basis. We expected a midday depression in the diurnal course of light interception both at the whole-crown and leaf scales, as a strategy to avoid the interception of excessive irradiance. We tested this hypothesis in a population of guava trees ( Psidium guajava L.) growing in an open tropical grassland. We quantified three crown architectural traits: intra-individual heterogeneity in foliage clumping, crown openness, and leaf position angles. We estimated the diurnal course of light interception at the crown scale using hemispheric photographs, and at the leaf scale using the cosine of solar incidence. Crowns showed a midday depression in light interception, while leaves showed a midday peak. These contrasting patterns were related to architectural traits. At the crown scale, the midday depression of light interception was linked to a greater crown openness and foliage clumping in crown tops than in the lateral parts of the crown. At the leaf scale, an average inclination angle of 45° led to the midday peak in light interception, but with a huge among-leaf variation in position angles. The mismatch in diurnal course of light interception at crown and leaf scales can indicate that different processes are being optimized at each scale. These findings suggest that the diurnal course of light interception may be an important dimension of the resource acquisition strategies of long-lived woody plants. Using a temporal approach as the one applied here may improve our understanding of the diversity of crown architectures found across and within environments.

Midday Depression vs. Midday Peak in Diurnal Light Interception: Contrasting Patterns at Crown and Leaf Scales in a Tropical Evergreen Tree

PubMed Central

Ventre-Lespiaucq, Agustina; Flanagan, Nicola S.; Ospina-Calderón, Nhora H.; Delgado, Juan A.; Escudero, Adrián

2018-01-01

Crown architecture usually is heterogeneous as a result of foraging in spatially and temporally heterogeneous light environments. Ecologists are only beginning to identify the importance of temporal heterogeneity for light acquisition in plants, especially at the diurnal scale. Crown architectural heterogeneity often leads to a diurnal variation in light interception. However, maximizing light interception during midday may not be an optimal strategy in environments with excess light. Instead, long-lived plants are expected to show crown architectures and leaf positions that meet the contrasting needs of light interception and avoidance of excess light on a diurnal basis. We expected a midday depression in the diurnal course of light interception both at the whole-crown and leaf scales, as a strategy to avoid the interception of excessive irradiance. We tested this hypothesis in a population of guava trees (Psidium guajava L.) growing in an open tropical grassland. We quantified three crown architectural traits: intra-individual heterogeneity in foliage clumping, crown openness, and leaf position angles. We estimated the diurnal course of light interception at the crown scale using hemispheric photographs, and at the leaf scale using the cosine of solar incidence. Crowns showed a midday depression in light interception, while leaves showed a midday peak. These contrasting patterns were related to architectural traits. At the crown scale, the midday depression of light interception was linked to a greater crown openness and foliage clumping in crown tops than in the lateral parts of the crown. At the leaf scale, an average inclination angle of 45° led to the midday peak in light interception, but with a huge among-leaf variation in position angles. The mismatch in diurnal course of light interception at crown and leaf scales can indicate that different processes are being optimized at each scale. These findings suggest that the diurnal course of light interception may be an important dimension of the resource acquisition strategies of long-lived woody plants. Using a temporal approach as the one applied here may improve our understanding of the diversity of crown architectures found across and within environments. PMID:29904391

Context effects on smooth pursuit and manual interception of a disappearing target.

PubMed

Kreyenmeier, Philipp; Fooken, Jolande; Spering, Miriam

2017-07-01

In our natural environment, we interact with moving objects that are surrounded by richly textured, dynamic visual contexts. Yet most laboratory studies on vision and movement show visual objects in front of uniform gray backgrounds. Context effects on eye movements have been widely studied, but it is less well known how visual contexts affect hand movements. Here we ask whether eye and hand movements integrate motion signals from target and context similarly or differently, and whether context effects on eye and hand change over time. We developed a track-intercept task requiring participants to track the initial launch of a moving object ("ball") with smooth pursuit eye movements. The ball disappeared after a brief presentation, and participants had to intercept it in a designated "hit zone." In two experiments ( n = 18 human observers each), the ball was shown in front of a uniform or a textured background that either was stationary or moved along with the target. Eye and hand movement latencies and speeds were similarly affected by the visual context, but eye and hand interception (eye position at time of interception, and hand interception timing error) did not differ significantly between context conditions. Eye and hand interception timing errors were strongly correlated on a trial-by-trial basis across all context conditions, highlighting the close relation between these responses in manual interception tasks. Our results indicate that visual contexts similarly affect eye and hand movements but that these effects may be short-lasting, affecting movement trajectories more than movement end points. NEW & NOTEWORTHY In a novel track-intercept paradigm, human observers tracked a briefly shown object moving across a textured, dynamic context and intercepted it with their finger after it had disappeared. Context motion significantly affected eye and hand movement latency and speed, but not interception accuracy; eye and hand position at interception were correlated on a trial-by-trial basis. Visual context effects may be short-lasting, affecting movement trajectories more than movement end points. Copyright © 2017 the American Physiological Society.

Genome-wide association analysis to identify genotype × environment interaction for milk protein yield and level of somatic cell score as environmental descriptors in German Holsteins.

PubMed

Streit, M; Reinhardt, F; Thaller, G; Bennewitz, J

2013-01-01

Genotype by environment interaction (G × E) has been widely reported in dairy cattle. If the environment can be measured on a continuous scale, reaction norms can be applied to study G × E. The average herd milk production level has frequently been used as an environmental descriptor because it is influenced by the level of feeding or the feeding regimen. Another important environmental factor is the level of udder health and hygiene, for which the average herd somatic cell count might be a descriptor. In the present study, we conducted a genome-wide association analysis to identify single nucleotide polymorphisms (SNP) that affect intercept and slope of milk protein yield reaction norms when using the average herd test-day solution for somatic cell score as an environmental descriptor. Sire estimates for intercept and slope of the reaction norms were calculated from around 12 million daughter records, using linear reaction norm models. Sires were genotyped for ~54,000 SNP. The sire estimates were used as observations in the association analysis, using 1,797 sires. Significant SNP were confirmed in an independent validation set consisting of 500 sires. A known major gene affecting protein yield was included as a covariable in the statistical model. Sixty (21) SNP were confirmed for intercept with P ≤ 0.01 (P ≤ 0.001) in the validation set, and 28 and 11 SNP, respectively, were confirmed for slope. Most but not all SNP affecting slope also affected intercept. Comparison with an earlier study revealed that SNP affecting slope were, in general, also significant for slope when the environment was modeled by the average herd milk production level, although the two environmental descriptors were poorly correlated. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Mutual information-based LPI optimisation for radar network

NASA Astrophysics Data System (ADS)

Shi, Chenguang; Zhou, Jianjiang; Wang, Fei; Chen, Jun

2015-07-01

Radar network can offer significant performance improvement for target detection and information extraction employing spatial diversity. For a fixed number of radars, the achievable mutual information (MI) for estimating the target parameters may extend beyond a predefined threshold with full power transmission. In this paper, an effective low probability of intercept (LPI) optimisation algorithm is presented to improve LPI performance for radar network. Based on radar network system model, we first provide Schleher intercept factor for radar network as an optimisation metric for LPI performance. Then, a novel LPI optimisation algorithm is presented, where for a predefined MI threshold, Schleher intercept factor for radar network is minimised by optimising the transmission power allocation among radars in the network such that the enhanced LPI performance for radar network can be achieved. The genetic algorithm based on nonlinear programming (GA-NP) is employed to solve the resulting nonconvex and nonlinear optimisation problem. Some simulations demonstrate that the proposed algorithm is valuable and effective to improve the LPI performance for radar network.

Switchgrass leaf area index and light extinction coefficients

USDA-ARS?s Scientific Manuscript database

Biomass production simulation modeling for plant species is often dependent upon accurate simulation or measurement of canopy light interception and radiation use efficiency. With the recent interest in converting large tracts of land to biofuel species cropping, modeling vegetative yield with grea...

Interception of spray drift by border structures. Part 1: wind tunnel experiments.

PubMed

De Schampheleire, M; Nuyttens, D; Dekeyser, D; Verboven, P; Cornelis, W; Gabriels, D; Spanoghe, P

2008-01-01

This research investigated the drift-intercepting potential of structures surrounding the field borders, like artificial screens and crops, which are not yet a part of the drift mitigation measures for field crop sprayers in Belgium. Drift-interception experiments were performed in the wind tunnel of the International Centre for Eremology (Ghent University, Belgium) with various interception structures: Artificial screens with heights of 0.5, 0.75 and 1 m and screen open areas of 16, 36 and 63%; a row of plastic Christmas trees with heights of 0.5 and 0.75 m; and a potato canopy. The interception structure was positioned at 1 m from the field border. From the results it was found that type of border structure has a pronounced effect on the drift interception, while the height of the border structure had no significant effect.

Gross rainfall amount and maximum rainfall intensity in 60-minute influence on interception loss of shrubs: a 10-year observation in the Tengger Desert.

PubMed

Zhang, Zhi-Shan; Zhao, Yang; Li, Xin-Rong; Huang, Lei; Tan, Hui-Juan

2016-05-17

In water-limited regions, rainfall interception is influenced by rainfall properties and crown characteristics. Rainfall properties, aside from gross rainfall amount and duration (GR and RD), maximum rainfall intensity and rainless gap (RG), within rain events may heavily affect throughfall and interception by plants. From 2004 to 2014 (except for 2007), individual shrubs of Caragana korshinskii and Artemisia ordosica were selected to measure throughfall during 210 rain events. Various rainfall properties were auto-measured and crown characteristics, i.e., height, branch and leaf area index, crown area and volume of two shrubs were also measured. The relative interceptions of C. korshinskii and A. ordosica were 29.1% and 17.1%, respectively. Rainfall properties have more contributions than crown characteristics to throughfall and interception of shrubs. Throughfall and interception of shrubs can be explained by GR, RI60 (maximum rainfall intensities during 60 min), RD and RG in deceasing importance. However, relative throughfall and interception of two shrubs have different responses to rainfall properties and crown characteristics, those of C. korshinskii were closely related to rainfall properties, while those of A. ordosica were more dependent on crown characteristics. We highlight long-term monitoring is very necessary to determine the relationships between throughfall and interception with crown characteristics.

Estimating the price elasticity of beer: meta-analysis of data with heterogeneity, dependence, and publication bias.

PubMed

Nelson, Jon P

2014-01-01

Precise estimates of price elasticities are important for alcohol tax policy. Using meta-analysis, this paper corrects average beer elasticities for heterogeneity, dependence, and publication selection bias. A sample of 191 estimates is obtained from 114 primary studies. Simple and weighted means are reported. Dependence is addressed by restricting number of estimates per study, author-restricted samples, and author-specific variables. Publication bias is addressed using funnel graph, trim-and-fill, and Egger's intercept model. Heterogeneity and selection bias are examined jointly in meta-regressions containing moderator variables for econometric methodology, primary data, and precision of estimates. Results for fixed- and random-effects regressions are reported. Country-specific effects and sample time periods are unimportant, but several methodology variables help explain the dispersion of estimates. In models that correct for selection bias and heterogeneity, the average beer price elasticity is about -0.20, which is less elastic by 50% compared to values commonly used in alcohol tax policy simulations. Copyright © 2013 Elsevier B.V. All rights reserved.

Neighborhood influences on the association between maternal age and birthweight: a multilevel investigation of age-related disparities in health.

PubMed

Cerdá, Magdalena; Buka, Stephen L; Rich-Edwards, Janet W

2008-05-01

It was hypothesized that the relationship between maternal age and infant birthweight varies significantly across neighborhoods and that such variation can be predicted by neighborhood characteristics. We analyzed 229,613 singleton births of mothers aged 20-45 years from Chicago, USA in 1997-2002. Random coefficient models were used to estimate the between-neighborhood variation in age-birthweight slopes, and both intercepts- and-slopes-as-outcomes models were used to evaluate area-level predictors of such variation. The crude maternal age-birthweight slopes for neighborhoods ranged from a decrease of 17 g to an increase of 10 g per year of maternal age. Adjustment for individual-level covariates reduced but did not eliminate this between-neighborhood variation. Concentrated poverty was a significant neighborhood-level predictor of the age-birthweight slope, explaining 44.4% of the between-neighborhood variation in slopes. Neighborhoods of higher economic disadvantage showed a more negative age-birthweight slope. The findings support the hypothesis that the relationship between maternal age and birthweight varies between neighborhoods. Indicators of neighborhood disadvantage help to explain such differences.

Aggressive crime, alcohol and drug use, and concentrated poverty in 24 U.S. urban areas.

PubMed

Valdez, Avelardo; Kaplan, Charles D; Curtis, Russell L

2007-01-01

The nexus between substance use and aggressive crime involves a complex interrelationship among mediating individual and community-level variables. Using multilevel logistic regression models, we investigate how community-level concentration of poverty variables mediate the predictive relationships among individual level social attachment variables and substance use on aggressive crime in a large national sample of male arrestees (N = 20,602) drawn from 24 U.S. urban areas. The findings support our hypothesis that individual social attachments to marriage and the labor force (education and employment) are the principal individual-level pathway mediating the substance abuse/aggression nexus. In the random intercept model, 3.17% of the variation not explained by the individual-level predictor variables is attributable to community-level variation in urban area female-headed households and households receiving welfare. This confirms our hypothesis that social structural conditions of an urban environment differentially expose persons to conditions that predict being arrested for an aggressive crime. Our findings tend to counter the cultural theorists who argue for an indigenous culture of violence in inner-city ghettos and barrios.

The potential of detecting intermediate-scale biomass and canopy interception in a coniferous forest using cosmic-ray neutron intensity measurements and neutron transport modeling

NASA Astrophysics Data System (ADS)

Andreasen, M.; Looms, M. C.; Bogena, H. R.; Desilets, D.; Zreda, M. G.; Sonnenborg, T. O.; Jensen, K. H.

2014-12-01

The water stored in the various compartments of the terrestrial ecosystem (in snow, canopy interception, soil and litter) controls the exchange of the water and energy between the land surface and the atmosphere. Therefore, measurements of the water stored within these pools are critical for the prediction of e.g. evapotranspiration and groundwater recharge. The detection of cosmic-ray neutron intensity is a novel non-invasive method for the quantification of continuous intermediate-scale soil moisture. The footprint of the cosmic-ray neutron probe is a hemisphere of a few hectometers and subsurface depths of 10-70 cm depending on wetness. The cosmic-ray neutron method offers measurements at a scale between the point-scale measurements and large-scale satellite retrievals. The cosmic-ray neutron intensity is inversely correlated to the hydrogen stored within the footprint. Overall soil moisture represents the largest pool of hydrogen and changes in the soil moisture clearly affect the cosmic-ray neutron signal. However, the neutron intensity is also sensitive to variations of hydrogen in snow, canopy interception and biomass offering the potential to determine water content in such pools from the signal. In this study we tested the potential of determining canopy interception and biomass using cosmic-ray neutron intensity measurements within the framework of the Danish Hydrologic Observatory (HOBE) and the Terrestrial Environmental Observatories (TERENO). Continuous measurements at the ground and the canopy level, along with profile measurements were conducted at towers at forest field sites. Field experiments, including shielding the cosmic-ray neutron probes with cadmium foil (to remove lower-energy neutrons) and measuring reference intensity rates at complete water saturated conditions (on the sea close to the HOBE site), were further conducted to obtain an increased understanding of the physics controlling the cosmic-ray neutron transport and the equipment used. Additionally, neutron transport modeling, using the extended version of the Monte Carlo N-Particle Transport Code, was conducted. The responses of the reference condition, different amounts of biomass, soil moisture and canopy interception on the cosmic-ray neutron intensity were simulated and compared to the measurements.

Estimation of Stormwater Interception Rate for various LID Facilities

NASA Astrophysics Data System (ADS)

Kim, S.; Lee, O.; Choi, J.

2017-12-01

In this study, the stormwater interception rate is proposed to apply in the design of LID facilities. For this purpose, EPA-SWMM is built with some areas of Noksan National Industrial Complex where long-term observed stormwater data were monitored and stormwater interception rates for various design capacities of various LID facilities are estimated. While the sensitivity of stormwater interception rate according to design specifications of bio-retention and infiltration trench facilities is not large, the sensitivity of stormwater interception rate according to local rainfall characteristics is relatively big. As a result of comparing the present rainfall interception rate estimation method which is officially operated in Korea with the one proposed in this study, it will be presented that the present method is highly likely to overestimate the performance of the bio-retention and infiltration trench facilities. Finally, a new stormwater interception rate formulas for the bio-retention and infiltration trench LID facilities will be proposed. Acknowledgement This research was supported by a grant (2016000200002) from Public Welfare Technology Development Program funded by Ministry of Environment of Korean government.

Climbing plants in a temperate rainforest understorey: searching for high light or coping with deep shade?

PubMed

Valladares, Fernando; Gianoli, Ernesto; Saldaña, Alfredo

2011-08-01

While the climbing habit allows vines to reach well-lit canopy areas with a minimum investment in support biomass, many of them have to survive under the dim understorey light during certain stages of their life cycle. But, if the growth/survival trade-off widely reported for trees hold for climbing plants, they cannot maximize both light-interception efficiency and shade avoidance (i.e. escaping from the understorey). The seven most important woody climbers occurring in a Chilean temperate evergreen rainforest were studied with the hypothesis that light-capture efficiency of climbers would be positively associated with their abundance in the understorey. Species abundance in the understorey was quantified from their relative frequency and density in field plots, the light environment was quantified by hemispherical photography, the photosynthetic response to light was measured with portable gas-exchange analyser, and the whole shoot light-interception efficiency and carbon gain was estimated with the 3-D computer model Y-plant. Species differed in specific leaf area, leaf mass fraction, above ground leaf area ratio, light-interception efficiency and potential carbon gain. Abundance of species in the understorey was related to whole shoot features but not to leaf level features such as specific leaf area. Potential carbon gain was inversely related to light-interception efficiency. Mutual shading among leaves within a shoot was very low (<20 %). The abundance of climbing plants in this southern rainforest understorey was directly related to their capacity to intercept light efficiently but not to their potential carbon gain. The most abundant climbers in this ecosystem match well with a shade-tolerance syndrome in contrast to the pioneer-like nature of climbers observed in tropical studies. The climbers studied seem to sacrifice high-light searching for coping with the dim understorey light.

Physiological and Technical Demands of No Dribble Game Drill in Young Basketball Players.

PubMed

Conte, Daniele; Favero, Terence G; Niederhausen, Meike; Capranica, Laura; Tessitore, Antonio

2015-12-01

This study assessed the physiological and technical demands of no dribble game drill (NDGD) in comparison with a regular drill (RD). Twenty-three young basketball players performed RDs and NDGDs in a random order. All basketball rules were followed for RDs, whereas dribbling was not permitted for NDGDs. The independent variable was the drill condition, and the dependent variables were percentage of maximal heart rate (%HRmax), rate of perceived exertion (RPE), Edwards training load (TL), and the following technical actions (TAs): pass (total, correct, wrong, and percent of correct passes), shot (total, scored, missed, and percent of made shots), interception, steal, turnover, and rebound. Wilcoxon signed-rank tests were applied to assess differences between NDGD and RD conditions for each dependent variable, and the level of statistical significance was set at p ≤ 0.05. Results showed higher values for %HRmax (p = 0.007), Edwards TL (p = 0.006), and RPE (p = 0.027) in NDGD compared with RD condition. Technical action analysis revealed higher values in NDGD than RD for total (p = 0.000), correct (p = 0.000), and wrong pass (p = 0.005), and interception (p = 0.001), whereas no significant differences were found for the other TAs. The main finding of this study was that NDGD condition elicited a greater physiological demand and a higher number of passes and interceptions than the RD one. Basketball coaches should consider the NDGD as a viable method to increase the physiological load of their training sessions and to teach passing skills in a game-based situation.

Process-based rainfall interception by small trees in Northern China: The effect of rainfall traits and crown structure characteristics

Treesearch

Xiang Li; Qingfu Xiao; Jianzhi Niu; Salli Dymond; Natalie S. van Doorn; Xinxiao Yu; Baoyuan Xie; Xizhi Lv; Kebin Zhang; Jiao Li

2016-01-01

Rainfall interception by a tree's crown is one of the most important hydrological processes in an ecosystem, yet the mechanisms of interception are not well understood. A process-based experiment was conducted under five simulated rainfall intensities (from 10 to 150 mm h−1) to directly quantify tree crown interception and examine the effect...

Gross rainfall amount and maximum rainfall intensity in 60-minute influence on interception loss of shrubs: a 10-year observation in the Tengger Desert

PubMed Central

Zhang, Zhi-Shan; Zhao, Yang; Li, Xin-Rong; Huang, Lei; Tan, Hui-Juan

2016-01-01

In water-limited regions, rainfall interception is influenced by rainfall properties and crown characteristics. Rainfall properties, aside from gross rainfall amount and duration (GR and RD), maximum rainfall intensity and rainless gap (RG), within rain events may heavily affect throughfall and interception by plants. From 2004 to 2014 (except for 2007), individual shrubs of Caragana korshinskii and Artemisia ordosica were selected to measure throughfall during 210 rain events. Various rainfall properties were auto-measured and crown characteristics, i.e., height, branch and leaf area index, crown area and volume of two shrubs were also measured. The relative interceptions of C. korshinskii and A. ordosica were 29.1% and 17.1%, respectively. Rainfall properties have more contributions than crown characteristics to throughfall and interception of shrubs. Throughfall and interception of shrubs can be explained by GR, RI60 (maximum rainfall intensities during 60 min), RD and RG in deceasing importance. However, relative throughfall and interception of two shrubs have different responses to rainfall properties and crown characteristics, those of C. korshinskii were closely related to rainfall properties, while those of A. ordosica were more dependent on crown characteristics. We highlight long-term monitoring is very necessary to determine the relationships between throughfall and interception with crown characteristics. PMID:27184918

Active space of pheromone plume and its relationship to effective attraction radius in applied models.

PubMed

Byers, John A

2008-09-01

The release rate of a semiochemical lure that attracts flying insects has a specific effective attraction radius (EAR) that corresponds to the lure's orientation response strength. EAR is defined as the radius of a passive sphere that intercepts the same number of insects as a semiochemical-baited trap. It is estimated by calculating the ratio of trap catches in the field in baited and unbaited traps and the interception area of the unbaited trap. EAR serves as a standardized method for comparing the attractive strengths of lures that is independent of population density. In two-dimensional encounter rate models that are used to describe insect mass trapping and mating disruption, a circular EAR (EAR(c)) describes a key parameter that affects catch or influence by pheromone in the models. However, the spherical EAR, as measured in the field, should be transformed to an EAR(c) for appropriate predictions in such models. The EAR(c) is calculated as (pi/2EAR(2))/F (L), where F (L) is the effective thickness of the flight layer where the insect searches. F (L) was estimated from catches of insects (42 species in the orders Coleoptera, Lepidoptera, Diptera, Hemiptera, and Thysanoptera) on traps at various heights as reported in the literature. The EAR(c) was proposed further as a simple but equivalent alternative to simulations of highly complex active-space plumes with variable response surfaces that have proven exceedingly difficult to quantify in nature. This hypothesis was explored in simulations where flying insects, represented as coordinate points, moved about in a correlated random walk in an area that contained a pheromone plume, represented as a sector of active space composed of a capture probability surface of variable complexity. In this plume model, catch was monitored at a constant density of flying insects and then compared to simulations in which a circular EAR(c) was enlarged until an equivalent rate was caught. This demonstrated that there is a circular EAR(c), where all insects that enter are caught, which corresponds in catch effect to any plume. Thus, the EAR(c), based on the field-observed EAR, can be used in encounter rate models to develop effective control programs based on mass trapping and/or mating disruption.

Fog interception by Ball moss (Tillandsia recurvata)

NASA Astrophysics Data System (ADS)

Guevara-Escobar, A.; Cervantes-Jiménez, M.; Suzán-Azpiri, H.; González-Sosa, E.; Hernández-Sandoval, L.; Malda-Barrera, G.; Martínez-Díaz, M.

2011-08-01

Interception losses are a major influence in the water yield of vegetated areas. For most storms, rain interception results in less water reaching the ground. However, fog interception can increase the overall water storage capacity of the vegetation and once the storage is exceeded, fog drip is a common hydrological input. Fog interception is disregarded in water budgets of semiarid regions, but for some plant communities, it could be a mechanism offsetting evaporation losses. Tillandsia recurvata is a cosmopolitan epiphyte adapted to arid habitats where fog may be an important water source. Therefore, the interception storage capacity by T. recurvata was measured in controlled conditions and applying simulated rain or fog. Juvenile, vegetative specimens were used to determine the potential upperbound storage capacities. The storage capacity was proportional to dry weight mass. Interception storage capacity (Cmin) was 0.19 and 0.56 mm for rainfall and fog respectively. The coefficients obtained in the laboratory were used together with biomass measurements for T. recurvata in a xeric scrub to calculate the depth of water intercepted by rain. T. recurvata contributed 20 % to the rain interception capacity of their shrub hosts: Acacia farnesiana and Prosopis laevigata and; also potentially intercepted 4.8 % of the annual rainfall. Nocturnal stomatic opening in T. recurvata is not only relevant for CO2 but for water vapor, as suggested by the higher weight change of specimens wetted with fog for 1 h at dark in comparison to those wetted during daylight (543 ± 77 vs. 325 ± 56 mg, p = 0.048). The storage capacity of T. recurvata leaf surfaces could increase the amount of water available for evaporation, but as this species colonise montane forests, the effect could be negative on water recharge, because potential storage capacity is very high, in the laboratory experiments it took up to 12 h at a rate of 0.26 l h-1 to reach saturation conditions when fog was applied.

Visual perception and interception of falling objects: a review of evidence for an internal model of gravity.

PubMed

Zago, Myrka; Lacquaniti, Francesco

2005-09-01

Prevailing views on how we time the interception of a moving object assume that the visual inputs are informationally sufficient to estimate the time-to-contact from the object's kinematics. However, there are limitations in the visual system that raise questions about the general validity of these theories. Most notably, vision is poorly sensitive to arbitrary accelerations. How then does the brain deal with the motion of objects accelerated by Earth's gravity? Here we review evidence in favor of the view that the brain makes the best estimate about target motion based on visually measured kinematics and an a priori guess about the causes of motion. According to this theory, a predictive model is used to extrapolate time-to-contact from the expected kinetics in the Earth's gravitational field.

Predicting declines in perceived relationship continuity using practice deprivation scores: a longitudinal study in primary care.

PubMed

Levene, Louis S; Baker, Richard; Walker, Nicola; Williams, Christopher; Wilson, Andrew; Bankart, John

2018-06-01

Increased relationship continuity in primary care is associated with better health outcomes, greater patient satisfaction, and fewer hospital admissions. Greater socioeconomic deprivation is associated with lower levels of continuity, as well as poorer health outcomes. To investigate whether deprivation scores predicted variations in the decline over time of patient-perceived relationship continuity of care, after adjustment for practice organisational and population factors. An observational study in 6243 primary care practices with more than one GP, in England, using a longitudinal multilevel linear model, 2012-2017 inclusive. Patient-perceived relationship continuity was calculated using two questions from the GP Patient Survey. The effect of deprivation on the linear slope of continuity over time was modelled, adjusting for nine confounding variables (practice population and organisational factors). Clustering of measurements within general practices was adjusted for by using a random intercepts and random slopes model. Descriptive statistics and univariable analyses were also undertaken. Relationship continuity declined by 27.5% between 2012 and 2017, and at all deprivation levels. Deprivation scores from 2012 did not predict variations in the decline of relationship continuity at practice level, after accounting for the effects of organisational and population confounding variables, which themselves did not predict, or weakly predicted with very small effect sizes, the decline of continuity. Cross-sectionally, continuity and deprivation were negatively correlated within each year. The decline in relationship continuity of care has been marked and widespread. Measures to maximise continuity will need to be feasible for individual practices with diverse population and organisational characteristics. © British Journal of General Practice 2018.

Not accounting for interindividual variability can mask habitat selection patterns: a case study on black bears.

PubMed

Lesmerises, Rémi; St-Laurent, Martin-Hugues

2017-11-01

Habitat selection studies conducted at the population scale commonly aim to describe general patterns that could improve our understanding of the limiting factors in species-habitat relationships. Researchers often consider interindividual variation in selection patterns to control for its effects and avoid pseudoreplication by using mixed-effect models that include individuals as random factors. Here, we highlight common pitfalls and possible misinterpretations of this strategy by describing habitat selection of 21 black bears Ursus americanus. We used Bayesian mixed-effect models and compared results obtained when using random intercept (i.e., population level) versus calculating individual coefficients for each independent variable (i.e., individual level). We then related interindividual variability to individual characteristics (i.e., age, sex, reproductive status, body condition) in a multivariate analysis. The assumption of comparable behavior among individuals was verified only in 40% of the cases in our seasonal best models. Indeed, we found strong and opposite responses among sampled bears and individual coefficients were linked to individual characteristics. For some covariates, contrasted responses canceled each other out at the population level. In other cases, interindividual variability was concealed by the composition of our sample, with the majority of the bears (e.g., old individuals and bears in good physical condition) driving the population response (e.g., selection of young forest cuts). Our results stress the need to consider interindividual variability to avoid misinterpretation and uninformative results, especially for a flexible and opportunistic species. This study helps to identify some ecological drivers of interindividual variability in bear habitat selection patterns.

A critique of the cross-lagged panel model.

PubMed

Hamaker, Ellen L; Kuiper, Rebecca M; Grasman, Raoul P P P

2015-03-01

The cross-lagged panel model (CLPM) is believed by many to overcome the problems associated with the use of cross-lagged correlations as a way to study causal influences in longitudinal panel data. The current article, however, shows that if stability of constructs is to some extent of a trait-like, time-invariant nature, the autoregressive relationships of the CLPM fail to adequately account for this. As a result, the lagged parameters that are obtained with the CLPM do not represent the actual within-person relationships over time, and this may lead to erroneous conclusions regarding the presence, predominance, and sign of causal influences. In this article we present an alternative model that separates the within-person process from stable between-person differences through the inclusion of random intercepts, and we discuss how this model is related to existing structural equation models that include cross-lagged relationships. We derive the analytical relationship between the cross-lagged parameters from the CLPM and the alternative model, and use simulations to demonstrate the spurious results that may arise when using the CLPM to analyze data that include stable, trait-like individual differences. We also present a modeling strategy to avoid this pitfall and illustrate this using an empirical data set. The implications for both existing and future cross-lagged panel research are discussed. (c) 2015 APA, all rights reserved).

Rainfall interception of three trees in Oakland, California

Treesearch

Qingfu Xiao; E. Gregory McPherson

2011-01-01

A rainfall interception study was conducted in Oakland, California to determine the partitioning of rainfall and the chemical composition of precipitation, throughfall, and stemflow. Rainfall interception measurements were conducted on a gingko (Ginkgo biloba) (13.5 m tall deciduous tree), sweet gum (Liquidambar styraciflua) (8...

Effects of an Interactive School-Based Program for Preventing Adolescent Sexual Harassment: A Cluster-Randomized Controlled Evaluation Study.

PubMed

de Lijster, Gaby P A; Felten, Hanneke; Kok, Gerjo; Kocken, Paul L

2016-05-01

Many adolescents experience sexual harassment and victims of sexual harassment have higher risks regarding well-being and health behaviors such as higher risks of suicidal thoughts, suicidal ideation and feeling unsafe at school. A peer-performed play and school lessons on preventing sexual harassment behavior were presented to secondary school students. We evaluated its effectiveness, using a cluster-randomized controlled design to assign schools to an experimental condition [n = 14 schools; 431 students (51 % female)] and a control condition [n = 11 schools; 384 students (51 % female)]. To measure the effects of the intervention at first post-test and 6-month follow-up, our multilevel analyses used a two-level random intercept model. Outcome measures were sexual harassment behaviors, behavioral determinants and distal factors influencing these behaviors. At post-test, students in the experimental group reported a reduced intention to commit sexual harassment behavior and higher self-efficacy in rejecting it. At post-test and follow-up there was a significant positive effect on social norms for rejecting sexual harassment behavior. At follow-up, sexual self-esteem was higher in students in the experimental group than in the control group. Effects on these determinants will benefit adolescents' future sexual behaviors. In combination, the play and lessons, possibly together with continued sexual health education and skills programs on social-emotional learning in subsequent school years, have potential for preventing sexual harassment behavior.

Stable estimate of primary OC/EC ratios in the EC tracer method

NASA Astrophysics Data System (ADS)

Chu, Shao-Hang

In fine particulate matter studies, the primary OC/EC ratio plays an important role in estimating the secondary organic aerosol contribution to PM2.5 concentrations using the EC tracer method. In this study, numerical experiments are carried out to test and compare various statistical techniques in the estimation of primary OC/EC ratios. The influence of random measurement errors in both primary OC and EC measurements on the estimation of the expected primary OC/EC ratios is examined. It is found that random measurement errors in EC generally create an underestimation of the slope and an overestimation of the intercept of the ordinary least-squares regression line. The Deming regression analysis performs much better than the ordinary regression, but it tends to overcorrect the problem by slightly overestimating the slope and underestimating the intercept. Averaging the ratios directly is usually undesirable because the average is strongly influenced by unrealistically high values of OC/EC ratios resulting from random measurement errors at low EC concentrations. The errors generally result in a skewed distribution of the OC/EC ratios even if the parent distributions of OC and EC are close to normal. When measured OC contains a significant amount of non-combustion OC Deming regression is a much better tool and should be used to estimate both the primary OC/EC ratio and the non-combustion OC. However, if the non-combustion OC is negligibly small the best and most robust estimator of the OC/EC ratio turns out to be the simple ratio of the OC and EC averages. It not only reduces random errors by averaging individual variables separately but also acts as a weighted average of ratios to minimize the influence of unrealistically high OC/EC ratios created by measurement errors at low EC concentrations. The median of OC/EC ratios ranks a close second, and the geometric mean of ratios ranks third. This is because their estimations are insensitive to questionable extreme values. A real world example is given using the ambient data collected from an Atlanta STN site during the winter of 2001-2002.

The impact of a disease management programme for type 2 diabetes on health-related quality of life: multilevel analysis of a cluster-randomised controlled trial.

PubMed

Panisch, Sigrid; Johansson, Tim; Flamm, Maria; Winkler, Henrike; Weitgasser, Raimund; Sönnichsen, Andreas C

2018-01-01

Type 2 diabetes is a chronic disease associated with poorer health outcomes and decreased health related quality of life (HRQoL). The aim of this analysis was to explore the impact of a disease management programme (DMP) in type 2 diabetes on HRQoL. A multilevel model was used to explain the variation in EQ-VAS. A cluster-randomized controlled trial-analysis of the secondary endpoint HRQoL. Our study population were general practitioners and patients in the province of Salzburg. The DMP "Therapie-Aktiv" was implemented in the intervention group, and controls received usual care. Outcome measure was a change in EQ-VAS after 12 months. For comparison of rates, we used Fisher's Exact test; for continuous variables the independent T test or Welch test were used. In the multilevel modeling, we examined various models, continuously adding variables to explain the variation in the dependent variable, starting with an empty model, including only the random intercept. We analysed random effects parameters in order to disentangle variation of the final EQ-VAS. The EQ-VAS significantly increased within the intervention group (mean difference 2.19, p = 0.005). There was no significant difference in EQ-VAS between groups (mean difference 1.00, p = 0.339). In the intervention group the improvement was more distinct in women (2.46, p = 0.036) compared to men (1.92, p = 0.063). In multilevel modeling, sex, age, family and work circumstances, any macrovascular diabetic complication, duration of diabetes, baseline body mass index and baseline EQ-VAS significantly influence final EQ-VAS, while DMP does not. The final model explains 28.9% (EQ-VAS) of the total variance. Most of the unexplained variance was found on patient-level (95%) and less on GP-level (5%). DMP "Therapie-Aktiv" has no significant impact on final EQ-VAS. The impact of DMPs in type 2 diabetes on HRQoL is still unclear and future programmes should focus on patient specific needs and predictors in order to improve HRQoL. Trial registration Current Controlled trials Ltd., ISRCTN27414162.

Testing the Hypothesis of the Multidimensional Model of Anorexia Nervosa in Adolescents.

ERIC Educational Resources Information Center

Lyon, Maureen; Chatoor, Irene; Atkins, Darlene; Silber, Tomas; Mosimann, James; Gray, James

1997-01-01

Tested six hypothesized risk factors of a model for anorexia nervosa. Results confirmed three of the risk factors: family history of depression, feelings of ineffectiveness, and poor interceptive awareness. Alcohol and drug abuse also figured prominently in the family history of patients with anorexia nervosa. (RJM)

The Impact of Noninvariant Intercepts in Latent Means Models

ERIC Educational Resources Information Center

Whittaker, Tiffany A.

2013-01-01

Latent means methods such as multiple-indicator multiple-cause (MIMIC) and structured means modeling (SMM) allow researchers to determine whether or not a significant difference exists between groups' factor means. Strong invariance is typically recommended when interpreting latent mean differences. The extent of the impact of noninvariant…

Need for speed: evaluating slopes of OCD recovery in behavior therapy enhanced with d-cycloserine.

PubMed

Chasson, Gregory S; Buhlmann, Ulrike; Tolin, David F; Rao, Sowmya R; Reese, Hannah E; Rowley, Theresa; Welsh, Kaitlyn S; Wilhelm, Sabine

2010-07-01

Evidence suggests that the antibiotic d-cycloserine (DCS) enhances the treatment effects of exposure and response prevention (ERP) for Obsessive-Compulsive Disorder (OCD). Further, evidence suggests that the effects of DCS diminish partway through treatment, but it is unclear to what extent. In an effort to evaluate these issues, the current study re-analyzes data from a 10-session randomized controlled trial of ERP+DCS versus ERP+placebo in a sample of 22 adults with OCD. We analyzed repeated-measures mixed models with random slopes and intercepts across different intervals: sessions 1-10, 1-5, and 6-10. The results indicate that the course of ERP was 2.3 times faster over the full 10 sessions for the DCS compared to the placebo group, and nearly six times quicker in the first half of ERP. Further interpretation of the results suggests that DCS does not amplify the effects of ERP, but instead initiates treatment effects sooner in treatment. In addition, DCS does not necessarily lose its effect over repeated use, but instead may exhaust its maximum utility after effectively jump-starting ERP. Ultimately, DCS may provide a means for curtailing treatment costs, decreasing treatment dropout and refusal rates, and enhancing access to care. Copyright 2010 Elsevier Ltd. All rights reserved.

Disentangling random thermal motion of particles and collective expansion of source from transverse momentum spectra in high energy collisions

NASA Astrophysics Data System (ADS)

Wei, Hua-Rong; Liu, Fu-Hu; Lacey, Roy A.

2016-12-01

In the framework of a multisource thermal model, we describe experimental results of the transverse momentum spectra of final-state light flavor particles produced in gold-gold (Au-Au), copper-copper (Cu-Cu), lead-lead (Pb-Pb), proton-lead (p-Pb), and proton-proton (p -p) collisions at various energies, measured by the PHENIX, STAR, ALICE, and CMS Collaborations, by using the Tsallis-standard (Tsallis form of Fermi-Dirac or Bose-Einstein), Tsallis, and two- or three-component standard distributions which can be in fact regarded as different types of ‘thermometers’ or ‘thermometric scales’ and ‘speedometers’. A central parameter in the three distributions is the effective temperature which contains information on the kinetic freeze-out temperature of the emitting source and reflects the effects of random thermal motion of particles as well as collective expansion of the source. To disentangle both effects, we extract the kinetic freeze-out temperature from the intercept of the effective temperature (T) curve as a function of particle’s rest mass (m 0) when plotting T versus m 0, and the mean transverse flow velocity from the slope of the mean transverse momentum (< {p}T> ) curve as a function of mean moving mass (\\overline{m}) when plotting < {p}T> versus \\overline{m}.

Does life satisfaction change in old age: results from an 8-year longitudinal study.

PubMed

Gana, Kamel; Bailly, Nathalie; Saada, Yaël; Joulain, Michèle; Alaphilippe, Daniel

2013-07-01

The unexpected positive relationship between aging and happiness was called "the paradox of well-being," which is still a matter of debate. This study examined longitudinal change in life satisfaction (LS) in older adults. LS was assessed with the satisfaction with life scale, in a sample of individuals (N = 899; aged 62-95 years, at first occasion; M = 72.73, SD = 5.68) for a period of 8 years (5 waves of data). A multiple indicator (e.g., second order) growth modeling was used to assess change in LS. Findings from both unconditional and conditional model (in which time-invariant, i.e., age, gender, and education, and time-varying, i.e., self-perceived health, covariates were incorporated in the model) indicated a linear increase in LS for the 8-year period. As expected, the results showed significant random variation in both intercept and slope, indicating that participants start at different levels and change at different rates. Our findings contribute to the debate concerning the paradox of well-being, which calls for explanation. There are few theories that provide some explanation (e.g., the socioemotional selectivity theory). However, to enhance researchers' understanding of developmental changes that contribute to the paradox of well-being, a more integrative theoretical model is needed.

Accounting for context in studies of health inequalities: a review and comparison of analytic approaches.

PubMed

Schempf, Ashley H; Kaufman, Jay S

2012-10-01

A common epidemiologic objective is to evaluate the contribution of residential context to individual-level disparities by race or socioeconomic position. We reviewed analytic strategies to account for the total (observed and unobserved factors) contribution of environmental context to health inequalities, including conventional fixed effects (FE) and hybrid FE implemented within a random effects (RE) or a marginal model. To illustrate results and limitations of the various analytic approaches of accounting for the total contextual component of health disparities, we used data on births nested within neighborhoods as an applied example of evaluating neighborhood confounding of racial disparities in gestational age at birth, including both a continuous and a binary outcome. Ordinary and RE models provided disparity estimates that can be substantially biased in the presence of neighborhood confounding. Both FE and hybrid FE models can account for cluster level confounding and provide disparity estimates unconfounded by neighborhood, with the latter having greater flexibility in allowing estimation of neighborhood-level effects and intercept/slope variability when implemented in a RE specification. Given the range of models that can be implemented in a hybrid approach and the frequent goal of accounting for contextual confounding, this approach should be used more often. Published by Elsevier Inc.

Effects of barbell deadlift training on submaximal motor unit firing rates for the vastus lateralis and rectus femoris.

PubMed

Stock, Matt S; Thompson, Brennan J

2014-01-01

Previous investigations that have studied motor unit firing rates following strength training have been limited to small muscles, isometric training, or interventions involving exercise machines. We examined the effects of ten weeks of supervised barbell deadlift training on motor unit firing rates for the vastus lateralis and rectus femoris during a 50% maximum voluntary contraction (MVC) assessment. Twenty-four previously untrained men (mean age  = 24 years) were randomly assigned to training (n = 15) or control (n = 9) groups. Before and following the intervention, the subjects performed isometric testing of the right knee extensors while bipolar surface electromyographic signals were detected from the two muscles. The signals were decomposed into their constituent motor unit action potential trains, and motor units that demonstrated accuracy levels less than 92.0% were not considered for analysis. One thousand eight hundred ninety-two and 2,013 motor units were examined for the vastus lateralis and rectus femoris, respectively. Regression analyses were used to determine the linear slope coefficients (pulses per second [pps]/% MVC) and y-intercepts (pps) of the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. Deadlift training significantly improved knee extensor MVC force (Cohen's d = .70), but did not influence force steadiness. Training had no influence on the slopes and y-intercepts for the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. In agreement with previous cross-sectional comparisons and randomized control trials, our findings do not support the notion that strength training affects the submaximal control of motor units.

A Bayesian Hierarchical Selection Model for Academic Growth with Missing Data

ERIC Educational Resources Information Center

Allen, Jeff

2017-01-01

Using a sample of schools testing annually in grades 9-11 with a vertically linked series of assessments, a latent growth curve model is used to model test scores with student intercepts and slopes nested within school. Missed assessments can occur because of student mobility, student dropout, absenteeism, and other reasons. Missing data…

Associations between environmental quality and mortality in ...

EPA Pesticide Factsheets

BACKGROUND: Assessing cumulative effects of the multiple environmental factors influencing mortality remains a challenging task. OBJECTIVES: This study aimed to examine the associations between cumulative environmental quality and all-cause and leading cause-specific (heart disease, cancer, and stroke) mortality rates. METHODS: We used the overall Environmental Quality Index (EQI) and its five domain indices (air, water, land, built, and sociodemographic) to represent environmental exposure. Associations between the EQI and mortality rates (CDC WONDER) for counties in the contiguous United States (n = 3,109) were investigated using multiple linear regression models and random intercept and random slope hierarchical models. Urbanicity, climate, and a combination of the two were used to explore the spatial patterns in the associations. RESULTS: We found 1 standard deviation increase in the overall EQI (worse environment) was associated with a mean 3.22% (95% Cl:2.80%, 3.64%) increase in all-cause mortality, a 0.54% (95% Cl: -0.17%, 1.25%) increase in heart disease mortality, a 2.71% (95% Cl: 2.21%, 3.22%) increase in cancer mortality, and a 2.25% (95% Cl: 1.11%, 3.39%) increase in stroke mortality. Among the environmental domains, the associations ranged from -1.27% (95% Cl: -1.70%,-0.84%) to 3.37% (95% Cl:2.90%, 3.84%),for all-cause mortality, -2.62% (95% Cl: -3.52%, -1.73%) to 4.50% (95% Cl:3.73%, 5.27%) for heart disease mortality, -0.88% (95% Cl:-2.12%, 0.36%)

Sampling procedures for throughfall monitoring: A simulation study

NASA Astrophysics Data System (ADS)

Zimmermann, Beate; Zimmermann, Alexander; Lark, Richard Murray; Elsenbeer, Helmut

2010-01-01

What is the most appropriate sampling scheme to estimate event-based average throughfall? A satisfactory answer to this seemingly simple question has yet to be found, a failure which we attribute to previous efforts' dependence on empirical studies. Here we try to answer this question by simulating stochastic throughfall fields based on parameters for statistical models of large monitoring data sets. We subsequently sampled these fields with different sampling designs and variable sample supports. We evaluated the performance of a particular sampling scheme with respect to the uncertainty of possible estimated means of throughfall volumes. Even for a relative error limit of 20%, an impractically large number of small, funnel-type collectors would be required to estimate mean throughfall, particularly for small events. While stratification of the target area is not superior to simple random sampling, cluster random sampling involves the risk of being less efficient. A larger sample support, e.g., the use of trough-type collectors, considerably reduces the necessary sample sizes and eliminates the sensitivity of the mean to outliers. Since the gain in time associated with the manual handling of troughs versus funnels depends on the local precipitation regime, the employment of automatically recording clusters of long troughs emerges as the most promising sampling scheme. Even so, a relative error of less than 5% appears out of reach for throughfall under heterogeneous canopies. We therefore suspect a considerable uncertainty of input parameters for interception models derived from measured throughfall, in particular, for those requiring data of small throughfall events.

Are Evidence-based Practices Associated With Effective Prevention of Hospital-acquired Pressure Ulcers in US Academic Medical Centers?

PubMed

Padula, William V; Gibbons, Robert D; Valuck, Robert J; Makic, Mary B F; Mishra, Manish K; Pronovost, Peter J; Meltzer, David O

2016-05-01

In 2008, the Centers for Medicare and Medicaid Services (CMS) established nonpayment policies resulting from costliness of hospital-acquired pressure ulcers (HAPUs) to hospitals. This prompted hospitals to adopt quality improvement (QI) interventions that increase use of evidence-based practices (EBPs) for HAPU prevention. To evaluate the longitudinal impact of CMS policy and QI adoption on HAPU rates. We characterized longitudinal adoption of 25 QI interventions that support EBPs through hospital leadership, staff, information technology, and performance and improvement. Quarterly counts of HAPU incidence and inpatient characteristics were collected from 55 University HealthSystem Consortium hospitals between 2007 and 2012. Mixed-effects regression models tested the longitudinal association of CMS policy, HAPU coding, and QI on HAPU rates. The models assumed level-2 random intercepts and random effects for CMS policy and EBP implementation to account for between-hospital variability in HAPU incidence. Controlling for all 25 QI interventions, specific updates to EBPs for HAPU prevention had a significant, though modest reduction on HAPU rates (-1.86 cases/quarter; P=0.002) and the effect of CMS nonpayment policy on HAPU prevention was much greater (-11.32 cases/quarter; P<0.001). HAPU rates were significantly lower after changes in CMS reimbursement. Reductions are associated with hospital-wide implementation of EBPs for HAPU prevention. Given that administrative data were used, it remains unknown whether these improvements were due to changes in coding or improved quality of care.

Are Evidence-based Practices Associated with Effective Prevention of Hospital-acquired Pressure Ulcers in U.S. Academic Medical Centers?

PubMed Central

Padula, William V.; Gibbons, Robert D.; Valuck, Robert J.; Makic, Mary Beth F.; Mishra, Manish K.; Pronovost, Peter J.; Meltzer, David O.

2016-01-01

Background In 2008, the Centers for Medicare and Medicaid Services (CMS) established nonpayment policies resulting from costliness of hospital-acquired pressure ulcers (HAPUs) to hospitals. This prompted hospitals to adopt quality improvement (QI) interventions that increase use of evidence-based practices (EBPs) for HAPU prevention. Objective To evaluate the longitudinal impact of CMS policy and QI adoption on HAPU rates. Methods We characterized longitudinal adoption of 25 QI interventions that support EBPs through hospital leadership, staff, information technology, and performance and improvement. Quarterly counts of HAPU incidence and inpatient characteristics were collected from 55 UHC hospitals between 2007–2012. Mixed-effects regression models tested the longitudinal association of CMS policy, HAPU coding and QI on HAPU rates. The models assumed level-2 random-intercepts and random effects for CMS policy and EBP implementation to account for between-hospital variability in HAPU incidence. Results Controlling for all 25 QI interventions, specific updates to EBPs for HAPU prevention had a significant, though modest reduction on HAPU rates (−1.86 cases/quarter; p=0.002) and the effect of CMS nonpayment policy on HAPU prevention was much greater (−11.32 cases/quarter; p<0.001). Conclusions HAPU rates were significantly lower following changes in CMS reimbursement. Reductions are associated with hospital-wide implementation of EBPs for HAPU prevention. Given that administrative data were used, it remains unknown whether these improvements were due to changes in coding or improved quality of care. PMID:27078824

Variation of Care Time Between Nursing Units in Classification-Based Nurse-to-Resident Ratios: A Multilevel Analysis

PubMed Central

Planer, Katarina; Hagel, Anja

2018-01-01

A validity test was conducted to determine how care level–based nurse-to-resident ratios compare with actual daily care times per resident in Germany. Stability across different long-term care facilities was tested. Care level–based nurse-to-resident ratios were compared with the standard minimum nurse-to-resident ratios. Levels of care are determined by classification authorities in long-term care insurance programs and are used to distribute resources. Care levels are a powerful tool for classifying authorities in long-term care insurance. We used observer-based measurement of assignable direct and indirect care time in 68 nursing units for 2028 residents across 2 working days. Organizational data were collected at the end of the quarter in which the observation was made. Data were collected from January to March, 2012. We used a null multilevel model with random intercepts and multilevel models with fixed and random slopes to analyze data at both the organization and resident levels. A total of 14% of the variance in total care time per day was explained by membership in nursing units. The impact of care levels on care time differed significantly between nursing units. Forty percent of residents at the lowest care level received less than the standard minimum registered nursing time per day. For facilities that have been significantly disadvantaged in the current staffing system, a higher minimum standard will function more effectively than a complex classification system without scientific controls. PMID:29442533

Variation of Care Time Between Nursing Units in Classification-Based Nurse-to-Resident Ratios: A Multilevel Analysis.

PubMed

Brühl, Albert; Planer, Katarina; Hagel, Anja

2018-01-01

A validity test was conducted to determine how care level-based nurse-to-resident ratios compare with actual daily care times per resident in Germany. Stability across different long-term care facilities was tested. Care level-based nurse-to-resident ratios were compared with the standard minimum nurse-to-resident ratios. Levels of care are determined by classification authorities in long-term care insurance programs and are used to distribute resources. Care levels are a powerful tool for classifying authorities in long-term care insurance. We used observer-based measurement of assignable direct and indirect care time in 68 nursing units for 2028 residents across 2 working days. Organizational data were collected at the end of the quarter in which the observation was made. Data were collected from January to March, 2012. We used a null multilevel model with random intercepts and multilevel models with fixed and random slopes to analyze data at both the organization and resident levels. A total of 14% of the variance in total care time per day was explained by membership in nursing units. The impact of care levels on care time differed significantly between nursing units. Forty percent of residents at the lowest care level received less than the standard minimum registered nursing time per day. For facilities that have been significantly disadvantaged in the current staffing system, a higher minimum standard will function more effectively than a complex classification system without scientific controls.

Information content versus word length in random typing

NASA Astrophysics Data System (ADS)

Ferrer-i-Cancho, Ramon; Moscoso del Prado Martín, Fermín

2011-12-01

Recently, it has been claimed that a linear relationship between a measure of information content and word length is expected from word length optimization and it has been shown that this linearity is supported by a strong correlation between information content and word length in many languages (Piantadosi et al 2011 Proc. Nat. Acad. Sci. 108 3825). Here, we study in detail some connections between this measure and standard information theory. The relationship between the measure and word length is studied for the popular random typing process where a text is constructed by pressing keys at random from a keyboard containing letters and a space behaving as a word delimiter. Although this random process does not optimize word lengths according to information content, it exhibits a linear relationship between information content and word length. The exact slope and intercept are presented for three major variants of the random typing process. A strong correlation between information content and word length can simply arise from the units making a word (e.g., letters) and not necessarily from the interplay between a word and its context as proposed by Piantadosi and co-workers. In itself, the linear relation does not entail the results of any optimization process.

Equations based on anthropometry to predict body fat measured by absorptiometry in schoolchildren and adolescents.

PubMed

Ortiz-Hernández, Luis; Vega López, A Valeria; Ramos-Ibáñez, Norma; Cázares Lara, L Joana; Medina Gómez, R Joab; Pérez-Salgado, Diana

To develop and validate equations to estimate the percentage of body fat of children and adolescents from Mexico using anthropometric measurements. A cross-sectional study was carried out with 601 children and adolescents from Mexico aged 5-19 years. The participants were randomly divided into the following two groups: the development sample (n=398) and the validation sample (n=203). The validity of previously published equations (e.g., Slaughter) was also assessed. The percentage of body fat was estimated by dual-energy X-ray absorptiometry. The anthropometric measurements included height, sitting height, weight, waist and arm circumferences, skinfolds (triceps, biceps, subscapular, supra-iliac, and calf), and elbow and bitrochanteric breadth. Linear regression models were estimated with the percentage of body fat as the dependent variable and the anthropometric measurements as the independent variables. Equations were created based on combinations of six to nine anthropometric variables and had coefficients of determination (r 2 ) equal to or higher than 92.4% for boys and 85.8% for girls. In the validation sample, the developed equations had high r 2 values (≥85.6% in boys and ≥78.1% in girls) in all age groups, low standard errors (SE≤3.05% in boys and ≤3.52% in girls), and the intercepts were not different from the origin (p>0.050). Using the previously published equations, the coefficients of determination were lower, and/or the intercepts were different from the origin. The equations developed in this study can be used to assess the percentage of body fat of Mexican schoolchildren and adolescents, as they demonstrate greater validity and lower error compared with previously published equations. Copyright © 2017 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

The statistics of Pearce element diagrams and the Chayes closure problem

NASA Astrophysics Data System (ADS)

Nicholls, J.

1988-05-01

Pearce element ratios are defined as having a constituent in their denominator that is conserved in a system undergoing change. The presence of a conserved element in the denominator simplifies the statistics of such ratios and renders them subject to statistical tests, especially tests of significance of the correlation coefficient between Pearce element ratios. Pearce element ratio diagrams provide unambigous tests of petrologic hypotheses because they are based on the stoichiometry of rock-forming minerals. There are three ways to recognize a conserved element: 1. The petrologic behavior of the element can be used to select conserved ones. They are usually the incompatible elements. 2. The ratio of two conserved elements will be constant in a comagmatic suite. 3. An element ratio diagram that is not constructed with a conserved element in the denominator will have a trend with a near zero intercept. The last two criteria can be tested statistically. The significance of the slope, intercept and correlation coefficient can be tested by estimating the probability of obtaining the observed values from a random population of arrays. This population of arrays must satisfy two criteria: 1. The population must contain at least one array that has the means and variances of the array of analytical data for the rock suite. 2. Arrays with the means and variances of the data must not be so abundant in the population that nearly every array selected at random has the properties of the data. The population of random closed arrays can be obtained from a population of open arrays whose elements are randomly selected from probability distributions. The means and variances of these probability distributions are themselves selected from probability distributions which have means and variances equal to a hypothetical open array that would give the means and variances of the data on closure. This hypothetical open array is called the Chayes array. Alternatively, the population of random closed arrays can be drawn from the compositional space available to rock-forming processes. The minerals comprising the available space can be described with one additive component per mineral phase and a small number of exchange components. This space is called Thompson space. Statistics based on either space lead to the conclusion that Pearce element ratios are statistically valid and that Pearce element diagrams depict the processes that create chemical inhomogeneities in igneous rock suites.

Nutritional status of under-five children in Bangladesh: a multilevel analysis.

PubMed

Alom, Jahangir; Quddus, Md Abdul; Islam, Mohammad Amirul

2012-09-01

The nutritional status of under-five children is a sensitive sign of a country's health status as well as economic condition. This study investigated the differential impact of some demographic, socioeconomic, environmental and health-related factors on the nutritional status among under-five children in Bangladesh using Bangladesh Demographic and Health Survey 2007 data. Two-level random intercept binary logistic regression models were used to identify the determinants of under-five malnutrition. The analyses revealed that 16% of the children were severely stunted and 25% were moderately stunted. Among the children under five years of age 3% were severely wasted and 14% were moderately wasted. Furthermore, 11% of the children were severely underweight and 28% were moderately underweight. The main contributing factors for under-five malnutrition were found to be child's age, mother's education, father's education, father's occupation, family wealth index, currently breast-feeding, place of delivery and division. Significant community-level variations were found in the analyses.

The Association of Workplace Social Capital With Work Engagement of Employees in Health Care Settings: A Multilevel Cross-Sectional Analysis.

PubMed

Fujita, Sumiko; Kawakami, Norito; Ando, Emiko; Inoue, Akiomi; Tsuno, Kanami; Kurioka, Sumiko; Kawachi, Ichiro

2016-03-01

The aim of the study was to examine the cross-sectional multilevel association between unit-level workplace social capital and individual-level work engagement among employees in health care settings. The data were collected from employees of a Japanese health care corporation using a questionnaire. The analyses were limited to 440 respondents from 35 units comprising five or more respondents per unit. Unit-level workplace social capital was calculated as an average score of the Workplace Social Capital Scale for each unit. Multilevel regression analysis with a random intercept model was conducted. After adjusting for demographic variables, unit-level workplace social capital was significantly and positively associated with respondents' work engagement (P < 0.001). The association remained significant after additionally adjusting for individual-level perceptions of workplace social capital (P < 0.001). Workplace social capital might exert a positive contextual effect on work engagement of employees in health care settings.

High-Throughput Analysis of Age-Dependent Protein Changes in Layer II/III of the Human Orbitofrontal Cortex

NASA Astrophysics Data System (ADS)

Kapadia, Fenika

Studies on the orbitofrontal cortex (OFC) during normal aging have shown a decline in cognitive functions, a loss of spines/synapses in layer III and gene expression changes related to neural communication. Biological changes during the course of normal aging are summarized into 9 hallmarks based on aging in peripheral tissue. Whether these hallmarks apply to non-dividing brain tissue is not known. Therefore, we opted to perform large-scale proteomic profiling of the OFC layer II/III during normal aging from 15 young and 18 old male subjects. MaxQuant was utilized for label-free quantification and statistical analysis by the Random Intercept Model (RIM) identified 118 differentially expressed (DE) age-related proteins. Altered neural communication was the most represented hallmark of aging (54% of DE proteins), highlighting the importance of communication in the brain. Functional analysis showed enrichment in GABA/glutamate signaling and pro-inflammatory responses. The former may contribute to alterations in excitation/inhibition, leading to cognitive decline during aging.

The Role of Ethnicity in Father Absence and Children’s School Enrollment in Guatemala

PubMed Central

2009-01-01

Despite the historical prevalence of single motherhood in Latin America and its rise in recent years, there is limited knowledge on the magnitude and consequences of father absence as experienced by children. Using a nationally representative sample from the 2002 Guatemalan Reproductive Health Survey, this study provides unprecedented documentation on the national prevalence of children’s separate living arrangements from their biological fathers and nonresident fathers’ paternity establishment and child support payments. Using random-intercept models, this study further demonstrates that father absence has a negative effect on the school enrollment of indigenous children of both sexes and Ladino male children. Increased poverty in father-absent households explains a smaller proportion of this adverse effect on indigenous children, suggesting that their fathers, when present, play a stronger social, rather than economic, role compared to their Ladino counterparts. Finally, child support payments attenuate the negative effects of father absence, particularly among Ladino male children. PMID:20694028

Can valproic acid be an inducer of clozapine metabolism?

PubMed Central

Diaz, Francisco J.; Eap, Chin B.; Ansermot, Nicolas; Crettol, Severine; Spina, Edoardo; de Leon, Jose

2014-01-01

Introduction Prior clozapine studies indicated no effects, mild inhibition or induction of valproic acid (VPA) on clozapine metabolism. The hypotheses that 1) VPA is a net inducer of clozapine metabolism, and 2) smoking modifies this inductive effect were tested in a therapeutic drug monitoring study. Methods After excluding strong inhibitors and inducers, 353 steady-state total clozapine (clozapine plus norclozapine) concentrations provided by 151 patients were analyzed using a random intercept linear model. Results VPA appeared to be an inducer of clozapine metabolism since total plasma clozapine concentrations in subjects taking VPA were significantly lower (27% lower; 95% confidence interval, 14% to 39%) after controlling for confounding variables including smoking (35% lower, 28% to 56%). Discussion Prospective studies are needed to definitively establish that VPA may 1) be an inducer of clozapine metabolism when induction prevails over competitive inhibition, and 2) be an inducer even in smokers who are under the influence of smoking inductive effects on clozapine metabolism. PMID:24764199

Tree Canopy Light Interception Estimates in Almond and a Walnut Orchards Using Ground, Low Flying Aircraft, and Satellite Based Methods to Improve Irrigation Scheduling Programs

NASA Technical Reports Server (NTRS)

Rosecrance, Richard C.; Johnson, Lee; Soderstrom, Dominic

2016-01-01

Canopy light interception is a main driver of water use and crop yield in almond and walnut production. Fractional green canopy cover (Fc) is a good indicator of light interception and can be estimated remotely from satellite using the normalized difference vegetation index (NDVI) data. Satellite-based Fc estimates could be used to inform crop evapotranspiration models, and hence support improvements in irrigation evaluation and management capabilities. Satellite estimates of Fc in almond and walnut orchards, however, need to be verified before incorporating them into irrigation scheduling or other crop water management programs. In this study, Landsat-based NDVI and Fc from NASA's Satellite Irrigation Management Support (SIMS) were compared with four estimates of canopy cover: 1. light bar measurement, 2. in-situ and image-based dimensional tree-crown analyses, 3. high-resolution NDVI data from low flying aircraft, and 4. orchard photos obtained via Google Earth and processed by an Image J thresholding routine. Correlations between the various estimates are discussed.

Tree canopy light interception estimates in almond and a walnut orchards using ground, low flying aircraft, and satellite based methods to improve irrigation scheduling programs.

NASA Astrophysics Data System (ADS)

Rosecrance, R. C.; Johnson, L.; Soderstrom, D.

2016-12-01

Canopy light interception is a main driver of water use and crop yield in almond and walnut production. Fractional green canopy cover (Fc) is a good indicator of light interception and can be estimated remotely from satellite using the normalized difference vegetation index (NDVI) data. Satellite-based Fc estimates could be used to inform crop evapotranspiration models, and hence support improvements in irrigation evaluation and management capabilities. Satellite estimates of Fc in almond and walnut orchards, however, need to be verified before incorporating them into irrigation scheduling or other crop water management programs. In this study, Landsat-based NDVI and Fc from NASA's Satellite Irrigation Management Support (SIMS) were compared with four estimates of canopy cover: 1. light bar measurement, 2. in-situ and image-based dimensional tree-crown analyses, 3. high-resolution NDVI data from low flying aircraft, and 4. orchard photos obtained via Google Earth and processed by an Image J thresholding routine. Correlations between the various estimates are discussed.

A simplified approach to the pooled analysis of calibration of clinical prediction rules for systematic reviews of validation studies

PubMed Central

Dimitrov, Borislav D; Motterlini, Nicola; Fahey, Tom

2015-01-01

Objective Estimating calibration performance of clinical prediction rules (CPRs) in systematic reviews of validation studies is not possible when predicted values are neither published nor accessible or sufficient or no individual participant or patient data are available. Our aims were to describe a simplified approach for outcomes prediction and calibration assessment and evaluate its functionality and validity. Study design and methods: Methodological study of systematic reviews of validation studies of CPRs: a) ABCD2 rule for prediction of 7 day stroke; and b) CRB-65 rule for prediction of 30 day mortality. Predicted outcomes in a sample validation study were computed by CPR distribution patterns (“derivation model”). As confirmation, a logistic regression model (with derivation study coefficients) was applied to CPR-based dummy variables in the validation study. Meta-analysis of validation studies provided pooled estimates of “predicted:observed” risk ratios (RRs), 95% confidence intervals (CIs), and indexes of heterogeneity (I2) on forest plots (fixed and random effects models), with and without adjustment of intercepts. The above approach was also applied to the CRB-65 rule. Results Our simplified method, applied to ABCD2 rule in three risk strata (low, 0–3; intermediate, 4–5; high, 6–7 points), indicated that predictions are identical to those computed by univariate, CPR-based logistic regression model. Discrimination was good (c-statistics =0.61–0.82), however, calibration in some studies was low. In such cases with miscalibration, the under-prediction (RRs =0.73–0.91, 95% CIs 0.41–1.48) could be further corrected by intercept adjustment to account for incidence differences. An improvement of both heterogeneities and P-values (Hosmer-Lemeshow goodness-of-fit test) was observed. Better calibration and improved pooled RRs (0.90–1.06), with narrower 95% CIs (0.57–1.41) were achieved. Conclusion Our results have an immediate clinical implication in situations when predicted outcomes in CPR validation studies are lacking or deficient by describing how such predictions can be obtained by everyone using the derivation study alone, without any need for highly specialized knowledge or sophisticated statistics. PMID:25931829

47 CFR 1.20003 - Policies and procedures for employee supervision and control.

Code of Federal Regulations, 2010 CFR

2010-10-01

... or employee responsible for ensuring that any interception of communications or access to call... to implement the interception of communications or access to call-identifying information; (2) An... description of how long it will maintain its records of each interception of communications or access to call...

Internal model of gravity for hand interception: parametric adaptation to zero-gravity visual targets on Earth.

PubMed

Zago, Myrka; Lacquaniti, Francesco

2005-08-01

Internal model is a neural mechanism that mimics the dynamics of an object for sensory motor or cognitive functions. Recent research focuses on the issue of whether multiple internal models are learned and switched to cope with a variety of conditions, or single general models are adapted by tuning the parameters. Here we addressed this issue by investigating how the manual interception of a moving target changes with changes of the visual environment. In our paradigm, a virtual target moves vertically downward on a screen with different laws of motion. Subjects are asked to punch a hidden ball that arrives in synchrony with the visual target. By using several different protocols, we systematically found that subjects do not develop a new internal model appropriate for constant speed targets, but they use the default gravity model and reduce the central processing time. The results imply that adaptation to zero-gravity targets involves a compression of temporal processing through the cortical and subcortical regions interconnected with the vestibular cortex, which has previously been shown to be the site of storage of the internal model of gravity.

Exploring the potential of the cosmic-ray neutron method to measure interception storage dynamics

NASA Astrophysics Data System (ADS)

Jakobi, Jannis; Bogena, Heye; Huisman, Johan Alexander; Diekkrüger, Bernd; Vereecken, Harry

2017-04-01

Cosmic-ray neutron soil moisture probes are an emerging technology that relies on the negative correlation between near-surface fast neutron counts and soil moisture content. Hydrogen atoms in the soil, which are mainly present as water, moderate the secondary neutrons on the way back to the surface. Any application of this method needs to consider the sensitivity of the neutron counts to additional sources of hydrogen (e.g. above- and below-ground biomass, humidity of the lower atmosphere, lattice water of the soil minerals, organic matter and water in the litter layer, intercepted water in the canopy, and soil organic matter). In this study, we analyzed the effects of canopy-intercepted water on the cosmic-ray neutron counts. For this, an arable field cropped with sugar beet was instrumented with several cosmic-ray neutron probes and a wireless sensor network with more than 140 in-situ soil moisture sensors. Additionally rainfall interception was estimated using a new approach coupling throughfall measurements and leaf wetness sensors. The derived interception storage was used to correct for interception effects on cosmic ray neutrons to enhance soil water content prediction. Furthermore, the potential for a simultaneous prediction of above- and below-ground biomass, soil moisture and interception was tested.

Fog interception by Sequoia sempervirens (D. Don) crowns decouples physiology from soil water deficit.

PubMed

Simonin, Kevin A; Santiago, Louis S; Dawson, Todd E

2009-07-01

Although crown wetting events can increase plant water status, leaf wetting is thought to negatively affect plant carbon balance by depressing photosynthesis and growth. We investigated the influence of crown fog interception on the water and carbon relations of juvenile and mature Sequoia sempervirens trees. Field observations of mature trees indicated that fog interception increased leaf water potential above that of leaves sheltered from fog. Furthermore, observed increases in leaf water potential exceeded the maximum water potential predicted if soil water was the only available water source. Because field observations were limited to two mature trees, we conducted a greenhouse experiment to investigate how fog interception influences plant water status and photosynthesis. Pre-dawn and midday branchlet water potential, leaf gas exchange and chlorophyll fluorescence were measured on S. sempervirens saplings exposed to increasing soil water deficit, with and without overnight canopy fog interception. Sapling fog interception increased leaf water potential and photosynthesis above the control and soil water deficit treatments despite similar dark-acclimated leaf chlorophyll fluorescence. The field observations and greenhouse experiment show that fog interception represents an overlooked flux into the soil-plant-atmosphere continuum that temporarily, but significantly, decouples leaf-level water and carbon relations from soil water availability.

The role of stable isotopes in understanding rainfall ...

EPA Pesticide Factsheets

The isotopic composition of water transmitted by the canopy as throughfall or stemflow reflects important hydrologic processes occurring in the canopy. A synthesis of the literature shows that complex spatiotemporal variations of isotopic composition are created by canopy interception. As a whole, the studies suggest a set of controlling factors including fractionation, exchange among liquid and vapor phase water, and spatiotemporal redistribution along varying canopy flowpaths. However, our limited understanding of physical processes and water routing in the canopy limits the ability to discern all details for predicting interception isotope effects. We suggest that the isotopic composition of throughfall and stemflow may be the key to improve our understanding of water storage and transport in the canopy, similar to how isotopic analysis contributed to progress in our understanding of watershed runoff processes. While interception isotope effects have largely been studied under the premise that they are a source of error, previous works also indicate a wide range of possible interactions that intercepted water may have with the canopy and airspace. We identify new research questions that may be answered by stable isotopes as a path forward in examining and generalizing small-scale interception processes that could facilitate integration of interception into watershed ecohydrological concepts. Evaporation from forest canopies (interception loss) is a prominent

An R2 statistic for fixed effects in the linear mixed model.

PubMed

Edwards, Lloyd J; Muller, Keith E; Wolfinger, Russell D; Qaqish, Bahjat F; Schabenberger, Oliver

2008-12-20

Statisticians most often use the linear mixed model to analyze Gaussian longitudinal data. The value and familiarity of the R(2) statistic in the linear univariate model naturally creates great interest in extending it to the linear mixed model. We define and describe how to compute a model R(2) statistic for the linear mixed model by using only a single model. The proposed R(2) statistic measures multivariate association between the repeated outcomes and the fixed effects in the linear mixed model. The R(2) statistic arises as a 1-1 function of an appropriate F statistic for testing all fixed effects (except typically the intercept) in a full model. The statistic compares the full model with a null model with all fixed effects deleted (except typically the intercept) while retaining exactly the same covariance structure. Furthermore, the R(2) statistic leads immediately to a natural definition of a partial R(2) statistic. A mixed model in which ethnicity gives a very small p-value as a longitudinal predictor of blood pressure (BP) compellingly illustrates the value of the statistic. In sharp contrast to the extreme p-value, a very small R(2) , a measure of statistical and scientific importance, indicates that ethnicity has an almost negligible association with the repeated BP outcomes for the study.

Anticipation of the landing shock phenomenon in flight simulation

NASA Technical Reports Server (NTRS)

Mcfarland, Richard E.

1987-01-01

An aircraft landing may be described as a controlled crash because a runway surface is intercepted. In a simulation model the transition from aerodynamic flight to weight on wheels involves a single computational cycle during which stiff differential equations are activated; with a significant probability these initial conditions are unrealistic. This occurs because of the finite cycle time, during which large restorative forces will accompany unrealistic initial oleo compressions. This problem was recognized a few years ago at Ames Research Center during simulation studies of a supersonic transport. The mathematical model of this vehicle severely taxed computational resources, and required a large cycle time. The ground strike problem was solved by a described technique called anticipation equations. This extensively used technique has not been previously reported. The technique of anticipating a significant event is a useful tool in the general field of discrete flight simulation. For the differential equations representing a landing gear model stiffness, rate of interception and cycle time may combine to produce an unrealistic simulation of the continuum.

How price responsive is the demand for specialty care?

PubMed

Maciejewski, Matthew L; Liu, Chuan-Fen; Kavee, Andrew L; Olsen, Maren K

2012-08-01

Outpatient visit co-payments have increased in recent years. We estimate the patient response to a price change for specialty care, based on a co-payment increase from $15 to $50 per visit for veterans with hypertension. A retrospective cohort of veterans required to pay co-payments was compared with veterans exempt from co-payments whose nonequivalence was reduced via propensity score matching. Specialty care expenditures in 2000-2003 were estimated via a two-part mixed model to account for the correlation of the use and level outcomes over time, and results from this correlated two-part model were compared with an uncorrelated two-part model and a correlated random intercept two-part mixed model. A $35 specialty visit co-payment increase had no impact on the likelihood of seeking specialty care but induced lower specialty expenditures over time among users who were required to pay co-payments. The log ratio of price responsiveness (semi-elasticity) for specialty care increased from -0.25 to -0.31 after the co-payment increase. Estimates were similar across the three models. A significant increase in specialty visit co-payments reduced specialty expenditures among patients obtaining medications at the Veterans Affairs medical centers. Longitudinal expenditure analysis may be improved using recent advances in two-part model methods. Published 2011. This article is a US Government work and is in the public domain in the USA.

Predicting snowpack stratigraphy in forested environments

NASA Astrophysics Data System (ADS)

Andreadis, K. M.; Lettenmaier, D. P.

2009-04-01

The interaction of forest canopies with snow accumulation and ablation processes is critical to the hydrology of many mid- and high-latitude areas. The layered character of snowpacks increases the complexity of representing these processes and deconvolving the return signal from remote sensors. However, it offers the opportunity to infer the metamorphic signature of the snowpack and to extract additional information by combining multiple frequencies (visible and passive/active microwave). Implementation of this approach requires knowledge of the stratigraphy of snowpack microphysical properties (temperature, density, and grain size), which as a practical matter can only be produced by predictive models. A mass and energy balance model for snow accumulation and ablation processes in forested environments was developed utilizing extensive measurements of snow interception and release in a maritime mountainous site in Oregon. A multiple layer component was added to the model that also takes into account snowpack stratigraphy resulting from snow densification, vapor transport and grain growth. The model, was evaluated using two years of weighing lysimeter data and was able to reproduce the SWE evolution throughout both winters beneath the canopy as well as the nearby clearing. The model was also evaluated using measurements from a BOReal Ecosystem-Atmosphere Study (BOREAS) field site in Canada to test the robustness of the canopy snow interception algorithm in a much different climate. Simulated SWE was relatively close to the observations for the forested sites, with discrepancies evident in some cases. Although the model formulation appeared robust for both types of climates, sensitivity to parameters such as snow roughness length, maximum interception capacity and number of layers suggested the magnitude of improvements of SWE simulations that might be achieved by calibration. Finally, the model's ability to replicate large-scale snowpack layer features and their effect on passive microwave emissivity was evaluated using observations from the Cold Land Processes Experiment (CLPX).

Differential Susceptibility and the Early Development of Aggression: Interactive Effects of Respiratory Sinus Arrhythmia and Environmental Quality

PubMed Central

Eisenberg, Nancy; Sulik, Michael J.; Spinrad, Tracy L.; Edwards, Alison; Eggum, Natalie D.; Liew, Jeffrey; Sallquist, Julie; Popp, Tierney K.; Smith, Cynthia L.; Hart, Daniel

2012-01-01

The purpose of the current study was to predict the development of aggressive behavior from young children’s respiratory sinus arrhythmia (RSA) and environmental quality. In a longitudinal sample of 213 children, baseline RSA, RSA suppression in response to a film of crying babies, and a composite measure of environmental quality (incorporating socioeconomic status and marital adjustment) were measured, and parent-reported aggression was assessed from 18 to 54 months of age. Predictions based on biological sensitivity-to-context/differential susceptibility and diathesis-stress models, as well as potential moderation by child sex, were examined. The interaction of baseline RSA with environmental quality predicted the development (slope) and 54-month intercept of mothers’ reports of aggression. For girls only, the interaction between baseline RSA and environmental quality predicted the 18-month intercept of fathers’ reports. In general, significant negative relations between RSA and aggression were found primarily at high levels of environmental quality. In addition, we found a significant Sex × RSA interaction predicting the slope and 54-month intercept of fathers’ reports of aggression, such that RSA was negatively related to aggression for boys but not for girls. Contrary to predictions, no significant main effects or interactions were found for RSA suppression. The results provide mixed but not full support for differential susceptibility theory and provide little support for the diathesis-stress model. PMID:22182294

Contrasting roles of interception and transpiration in the hydrological cycle - Part 2: Moisture recycling

NASA Astrophysics Data System (ADS)

van der Ent, R. J.; Wang-Erlandsson, L.; Keys, P. W.; Savenije, H. H. G.

2014-12-01

The contribution of land evaporation to local and remote precipitation (i.e. moisture recycling) is of significant importance to sustain water resources and ecosystems. But how important are different evaporation components in sustaining precipitation? This is the first paper to present moisture recycling metrics for partitioned evaporation. In the companion paper Wang-Erlandsson et al. (2014) (hereafter Part 1), evaporation was partitioned into vegetation interception, floor interception, soil moisture evaporation and open-water evaporation (constituting the direct, purely physical fluxes, largely dominated by interception), and transpiration (delayed, biophysical flux). Here, we track these components forward as well as backward in time. We also include age tracers to study the atmospheric residence times of these evaporation components. We present a new image of the global hydrological cycle that includes quantification of partitioned evaporation and moisture recycling as well as the atmospheric residence times of all fluxes. We demonstrate that evaporated interception is more likely to return as precipitation on land than transpired water. On average, direct evaporation (essentially interception) is found to have an atmospheric residence time of 8 days, while transpiration typically resides for 9 days in the atmosphere. The process scale over which evaporation recycles is more local for interception compared to transpiration; thus interception generally precipitates closer to its evaporative source than transpiration, which is particularly pronounced outside the tropics. We conclude that interception mainly works as an intensifier of the local hydrological cycle during wet spells and wet seasons. On the other hand, transpiration remains active during dry spells and dry seasons and is transported over much larger distances downwind, where it can act as a significant source of moisture. Thus, as various land-use types can differ considerably in their partitioning between interception and transpiration, our results stress that land-use changes (e.g. forest-to-cropland conversion) do not only affect the magnitude of moisture recycling, but could also influence the moisture recycling patterns and lead to a redistribution of water resources. As such, this research highlights that land-use changes can have complex effects on the atmospheric branch of the hydrological cycle.

Contrasting roles of interception and transpiration in the hydrological cycle - Part 2: Moisture recycling

NASA Astrophysics Data System (ADS)

van der Ent, R. J.; Wang-Erlandsson, L.; Keys, P. W.; Savenije, H. H. G.

2014-03-01

The contribution of land evaporation to local and remote precipitation (i.e., moisture recycling) is of significant importance to sustain water resources and ecosystems. But how important are different evaporation components in sustaining precipitation? This is the first paper to present moisture recycling metrics for partitioned evaporation. In the companion paper, Part 1, evaporation was partitioned into vegetation interception, floor interception, soil moisture evaporation and open water evaporation (constituting the direct, purely physical fluxes, largely dominated by interception), and transpiration (delayed, biophysical flux). Here, we track these components forward as well as backward in time. We also include age tracers to study the atmospheric residence times of these evaporation components. As the main result we present a new image of the global hydrological cycle that includes quantification of partitioned evaporation and moisture recycling as well as the atmospheric residence times of all fluxes. We demonstrate that evaporated interception is more likely to return as precipitation on land than transpired water. On average, direct evaporation (essentially interception) is found to have an atmospheric residence time of eight days, while transpiration typically resides nine days in the atmosphere. Interception recycling has a much shorter local length scale than transpiration recycling, thus interception generally precipitates closer to its evaporative source than transpiration, which is particularly pronounced outside the tropics. We conclude that interception mainly works as an intensifier of the local hydrological cycle during wet spells. On the other hand, transpiration remains active during dry spells and is transported over much larger distances downwind where it can act as a significant source of moisture. Thus, as various land-use types can differ considerably in their partitioning between interception and transpiration, our results stress that land-use changes (e.g., forest to cropland conversion) do not only affect the magnitude of moisture recycling, but could also influence the moisture recycling patterns and lead to a redistribution of water resources. As such, this research highlights that land-use changes can have complex effects on the atmospheric branch of the hydrological cycle.

Reliabilities of mental rotation tasks: limits to the assessment of individual differences.

PubMed

Hirschfeld, Gerrit; Thielsch, Meinald T; Zernikow, Boris

2013-01-01

Mental rotation tasks with objects and body parts as targets are widely used in cognitive neuropsychology. Even though these tasks are well established to study between-groups differences, the reliability on an individual level is largely unknown. We present a systematic study on the internal consistency and test-retest reliability of individual differences in mental rotation tasks comparing different target types and orders of presentations. In total n = 99 participants (n = 63 for the retest) completed the mental rotation tasks with hands, feet, faces, and cars as targets. Different target types were presented in either randomly mixed blocks or blocks of homogeneous targets. Across all target types, the consistency (split-half reliability) and stability (test-retest reliabilities) were good or acceptable both for intercepts and slopes. At the level of individual targets, only intercepts showed acceptable reliabilities. Blocked presentations resulted in significantly faster and numerically more consistent and stable responses. Mental rotation tasks-especially in blocked variants-can be used to reliably assess individual differences in global processing speed. However, the assessment of the theoretically important slope parameter for individual targets requires further adaptations to mental rotation tests.

Changes in organisation of instep kicking as a function of wearing compression and textured materials.

PubMed

Hasan, Hosni; Davids, Keith; Chow, Jia Yi; Kerr, Graham

2017-04-01

This study investigated effects of wearing compression garments and textured insoles on modes of movement organisation emerging during performance of lower limb interceptive actions in association football. Participants were six skilled (age = 15.67 ± 0.74 years) and six less-skilled (age = 15.17 ± 1.1 years) football players. All participants performed 20 instep kicks with maximum velocity in four randomly organised insoles and socks conditions, (a) Smooth Socks with Smooth Insoles (SSSI); (b) Smooth Socks with Textured Insoles (SSTI); (c) Compression Socks with Smooth Insoles (CSSI); and (d), Compression Socks with Textured Insoles (CSTI). Results showed that, when wearing textured and compression materials (CSSI condition), less-skilled participants displayed significantly greater hip extension and flexion towards the ball contact phase, indicating larger ranges of motion in the kicking limb than in other conditions. Less-skilled participants also demonstrated greater variability in knee-ankle intralimb (angle-angle plots) coordination modes in the CSTI condition. Findings suggested that use of textured and compression materials increased attunement to somatosensory information from lower limb movement, to regulate performance of dynamic interceptive actions like kicking, especially in less-skilled individuals.

Understanding the City Size Wage Gap*

PubMed Central

Baum-Snow, Nathaniel; Pavan, Ronni

2013-01-01

In this paper, we decompose city size wage premia into various components. We base these decompositions on an estimated on-the-job search model that incorporates latent ability, search frictions, firm-worker match quality, human capital accumulation and endogenous migration between large, medium and small cities. Counterfactual simulations of the model indicate that variation in returns to experience and differences in wage intercepts across location type are the most important mechanisms contributing to observed city size wage premia. Variation in returns to experience is more important for generating wage premia between large and small locations while differences in wage intercepts are more important for generating wage premia betwen medium and small locations. Sorting on unobserved ability within education group and differences in labor market search frictions and distributions of firm-worker match quality contribute little to observed city size wage premia. These conclusions hold for separate samples of high school and college graduates. PMID:24273347

Understanding the City Size Wage Gap.

PubMed

Baum-Snow, Nathaniel; Pavan, Ronni

2012-01-01

In this paper, we decompose city size wage premia into various components. We base these decompositions on an estimated on-the-job search model that incorporates latent ability, search frictions, firm-worker match quality, human capital accumulation and endogenous migration between large, medium and small cities. Counterfactual simulations of the model indicate that variation in returns to experience and differences in wage intercepts across location type are the most important mechanisms contributing to observed city size wage premia. Variation in returns to experience is more important for generating wage premia between large and small locations while differences in wage intercepts are more important for generating wage premia betwen medium and small locations. Sorting on unobserved ability within education group and differences in labor market search frictions and distributions of firm-worker match quality contribute little to observed city size wage premia. These conclusions hold for separate samples of high school and college graduates.

How might Australian rainforest cloud interception respond to climate change?

NASA Astrophysics Data System (ADS)

Wallace, Jim; McJannet, Dave

2013-02-01

SummaryThe lower and upper montane rainforests in northern Queensland receive significant amounts of cloud interception that affect both in situ canopy wetness and downstream runoff. Cloud interception contributes 5-30% of the annual water input to the canopy and this increases to 40-70% of the monthly water input during the dry season. This occult water is therefore an important input to the canopy, sustaining the epiphytes, mosses and other species that depend on wet canopy conditions. The potential effect of climate change on cloud interception was examined using the relationship between cloud interception and cloud frequency derived from measurements made at four different rainforest locations. Any given change in cloud frequency produces a greater change in cloud interception and this 'amplification' increases from 1.1 to 1.7 as cloud frequency increases from 5% to 70%. This means that any changes in cloud frequency will have the greatest relative effects at the higher altitude sites where cloud interception is greatest. As cloud frequency is also a major factor affecting canopy wetness, any given change in cloud frequency will therefore have a greater impact on canopy wetness at the higher altitude sites. These changes in wetness duration will augment those due to changes in rainfall and may have important implications for the fauna and flora that depend on wet canopy conditions. We also found that the Australian rainforests may be more efficient (by ˜50% on average) in intercepting cloud water than American coniferous forests, which may be due to differences in canopy structure and exposure at the different sites.

SHIIVER (Structural Heat Intercept Insulation Vibration Evaluation Rig)

NASA Image and Video Library

2017-06-11

SHIIVER (Structural Heat Intercept Insulation Vibration Evaluation Rig) is a cryogenic test tank developed to evaluate heat intercept concepts. It arrived at Marshall Space Flight Center on August 10, 2017. The tank will receive heat sensors and spray-on foam insulation before making its way to Plum Brook station for further insulation and testing.

Gravity settling

DOEpatents

Davis, Hyman R.; Long, R. H.; Simone, A. A.

1979-01-01

Solids are separated from a liquid in a gravity settler provided with inclined solid intercepting surfaces to intercept the solid settling path to coalesce the solids and increase the settling rate. The intercepting surfaces are inverted V-shaped plates, each formed from first and second downwardly inclined upwardly curved intersecting conical sections having their apices at the vessel wall.

Artificial night light alters nocturnal prey interception outcomes for morphologically variable spiders.

PubMed

Yuen, Suet Wai; Bonebrake, Timothy C

2017-01-01

Artificial night light has the potential to significantly alter visually-dependent species interactions. However, examples of disruptions of species interactions through changes in light remain rare and how artificial night light may alter predator-prey relationships are particularly understudied. In this study, we examined whether artificial night light could impact prey attraction and interception in Nephila pilipes orb weaver spiders, conspicuous predators who make use of yellow color patterns to mimic floral resources and attract prey to their webs. We measured moth prey attraction and interception responses to treatments where we experimentally manipulated the color/contrast of spider individuals in the field (removed yellow markings) and also set up light manipulations. We found that lit webs had lower rates of moth interception than unlit webs. Spider color, however, had no clear impact on moth interception or attraction rates in lit nor unlit webs. The results show that night light can reduce prey interception for spiders. Additionally, this study highlights how environmental and morphological variation can complicate simple predictions of ecological light pollution's disruption of species interactions.

The Impact of Biofuels on Climate Change from Marginal Land over East Asia using the RegCM4

NASA Astrophysics Data System (ADS)

Kim, S.; Lee, O.; Choi, J.

2016-12-01

In this study, the stormwater interception rate is proposed to apply in the design of LID facilities. For this purpose, EPA-SWMM is built with some areas of Noksan National Industrial Complex where long-term observed stormwater data were monitored and stormwater interception rates for various design capacities of various LID facilities are estimated. While the sensitivity of stormwater interception rate according to design specifications of bio-retention and infiltration trench facilities is not large, the sensitivity of stormwater interception rate according to local rainfall characteristics is relatively big. As a result of comparing the present rainfall interception rate estimation method which is officially operated in Korea with the one proposed in this study, it will be presented that the present method is highly likely to overestimate the performance of the bio-retention and infiltration trench facilities. Finally, a new stormwater interception rate formulas for the bio-retention and infiltration trench LID facilities will be proposed. Acknowledgement This research was supported by a grant (2016000200002) from Public Welfare Technology Development Program funded by Ministry of Environment of Korean government.

Right-Sizing Statistical Models for Longitudinal Data

PubMed Central

Wood, Phillip K.; Steinley, Douglas; Jackson, Kristina M.

2015-01-01

Arguments are proposed that researchers using longitudinal data should consider more and less complex statistical model alternatives to their initially chosen techniques in an effort to “right-size” the model to the data at hand. Such model comparisons may alert researchers who use poorly fitting overly parsimonious models to more complex better fitting alternatives, and, alternatively, may identify more parsimonious alternatives to overly complex (and perhaps empirically under-identified and/or less powerful) statistical models. A general framework is proposed for considering (often nested) relationships between a variety of psychometric and growth curve models. A three-step approach is proposed in which models are evaluated based on the number and patterning of variance components prior to selection of better-fitting growth models that explain both mean and variation/covariation patterns. The orthogonal, free-curve slope-intercept (FCSI) growth model is considered as a general model which includes, as special cases, many models including the Factor Mean model (FM, McArdle & Epstein, 1987), McDonald's (1967) linearly constrained factor model, Hierarchical Linear Models (HLM), Repeated Measures MANOVA, and the Linear Slope Intercept (LinearSI) Growth Model. The FCSI model, in turn, is nested within the Tuckerized factor model. The approach is illustrated by comparing alternative models in a longitudinal study of children's vocabulary and by comparison of several candidate parametric growth and chronometric models in a Monte Carlo study. PMID:26237507

Right-sizing statistical models for longitudinal data.

PubMed

Wood, Phillip K; Steinley, Douglas; Jackson, Kristina M

2015-12-01

Arguments are proposed that researchers using longitudinal data should consider more and less complex statistical model alternatives to their initially chosen techniques in an effort to "right-size" the model to the data at hand. Such model comparisons may alert researchers who use poorly fitting, overly parsimonious models to more complex, better-fitting alternatives and, alternatively, may identify more parsimonious alternatives to overly complex (and perhaps empirically underidentified and/or less powerful) statistical models. A general framework is proposed for considering (often nested) relationships between a variety of psychometric and growth curve models. A 3-step approach is proposed in which models are evaluated based on the number and patterning of variance components prior to selection of better-fitting growth models that explain both mean and variation-covariation patterns. The orthogonal free curve slope intercept (FCSI) growth model is considered a general model that includes, as special cases, many models, including the factor mean (FM) model (McArdle & Epstein, 1987), McDonald's (1967) linearly constrained factor model, hierarchical linear models (HLMs), repeated-measures multivariate analysis of variance (MANOVA), and the linear slope intercept (linearSI) growth model. The FCSI model, in turn, is nested within the Tuckerized factor model. The approach is illustrated by comparing alternative models in a longitudinal study of children's vocabulary and by comparing several candidate parametric growth and chronometric models in a Monte Carlo study. (c) 2015 APA, all rights reserved).

Guided training relative to direct skill training for individuals with cognitive impairments after stroke: a pilot randomized trial

PubMed Central

Skidmore, Elizabeth R.; Butters, Meryl; Whyte, Ellen; Grattan, Emily; Shen, Jennifer; Terhorst, Lauren

2016-01-01

Objective To examine the effects of direct skill training and guided training for promoting independence after stroke. Design Single-blind randomized pilot study. Setting Inpatient rehabilitation facility. Participants Forty-three participants in inpatient rehabilitation with acute stroke and cognitive impairments. Interventions Participants were randomized to receive direct skill training (n=22, 10 sessions as adjunct to usual inpatient rehabilitation) or guided training (n=21, same dose). Main Outcome Measure The Functional Independence Measure assessed independence at baseline, rehabilitation discharge, and months 3, 6, and 12. Results Linear mixed models (random intercept, other effects fixed) revealed a significant intervention by time interaction (F4,150=5.11, p<0.001), a significant main effect of time (F4,150=49.25, p<0.001), and a significant effect of stroke severity (F1,150=34.46, p<.001). There was no main effect of intervention (F1,150=0.07, p=0.79). Change in Functional Independence Measures scores was greater for the DIRECT group at rehabilitation discharge (effect size of between group differences, d=0.28) and greater for the GUIDE group at months 3 (d=0.16), 6 (d=0.39), and 12 (d=0.53). The difference between groups in mean 12 month change scores was 10.57 points. Conclusions Guided training, provided in addition to usual care, offered a small advantage in the recovery of independence, relative to direct skill training. Future studies examining guided training in combination with other potentially potent intervention elements may further advise best practices in rehabilitation for individuals with cognitive impairments after acute stroke. PMID:27794487

Detection of Differential Item Functioning Using the Lasso Approach

ERIC Educational Resources Information Center

Magis, David; Tuerlinckx, Francis; De Boeck, Paul

2015-01-01

This article proposes a novel approach to detect differential item functioning (DIF) among dichotomously scored items. Unlike standard DIF methods that perform an item-by-item analysis, we propose the "LR lasso DIF method": logistic regression (LR) model is formulated for all item responses. The model contains item-specific intercepts,…

The Development and Demonstration of Multiple Regression Models for Operant Conditioning Questions.

ERIC Educational Resources Information Center

Fanning, Fred; Newman, Isadore

Based on the assumption that inferential statistics can make the operant conditioner more sensitive to possible significant relationships, regressions models were developed to test the statistical significance between slopes and Y intercepts of the experimental and control group subjects. These results were then compared to the traditional operant…

Extending the Applicability of the Generalized Likelihood Function for Zero-Inflated Data Series

NASA Astrophysics Data System (ADS)

Oliveira, Debora Y.; Chaffe, Pedro L. B.; Sá, João. H. M.

2018-03-01

Proper uncertainty estimation for data series with a high proportion of zero and near zero observations has been a challenge in hydrologic studies. This technical note proposes a modification to the Generalized Likelihood function that accounts for zero inflation of the error distribution (ZI-GL). We compare the performance of the proposed ZI-GL with the original Generalized Likelihood function using the entire data series (GL) and by simply suppressing zero observations (GLy>0). These approaches were applied to two interception modeling examples characterized by data series with a significant number of zeros. The ZI-GL produced better uncertainty ranges than the GL as measured by the precision, reliability and volumetric bias metrics. The comparison between ZI-GL and GLy>0 highlights the need for further improvement in the treatment of residuals from near zero simulations when a linear heteroscedastic error model is considered. Aside from the interception modeling examples illustrated herein, the proposed ZI-GL may be useful for other hydrologic studies, such as for the modeling of the runoff generation in hillslopes and ephemeral catchments.

Calibrated intercepts for solar radiometers used in remote sensor calibration

NASA Technical Reports Server (NTRS)

Gellman, David I.; Biggar, Stuart F.; Slater, Philip N.; Bruegge, Carol J.

1991-01-01

Calibrated solar radiometer intercepts allow spectral optical depths to be determined for days with intermittently clear skies. This is of particular importance on satellite sensor calibration days that are cloudy except at the time of image acquisition. This paper describes the calibration of four solar radiometers using the Langley-Bouguer technique for data collected on days with a clear, stable atmosphere. Intercepts are determined with an uncertainty of less than six percent, corresponding to a maximum uncertainty of 0.06 in optical depth. The spread of voltage intercepts calculated in this process is carried through three methods of radiometric calibration of satellite sensors to yield an uncertainty in radiance at the top of the atmosphere of less than one percent associated with the uncertainty in solar radiometer intercepts for a range of ground reflectances.

Linear mixed-effects models to describe length-weight relationships for yellow croaker (Larimichthys Polyactis) along the north coast of China.

PubMed

Ma, Qiuyun; Jiao, Yan; Ren, Yiping

2017-01-01

In this study, length-weight relationships and relative condition factors were analyzed for Yellow Croaker (Larimichthys polyactis) along the north coast of China. Data covered six regions from north to south: Yellow River Estuary, Coastal Waters of Northern Shandong, Jiaozhou Bay, Coastal Waters of Qingdao, Haizhou Bay, and South Yellow Sea. In total 3,275 individuals were collected during six years (2008, 2011-2015). One generalized linear model, two simply linear models and nine linear mixed effect models that applied the effects from regions and/or years to coefficient a and/or the exponent b were studied and compared. Among these twelve models, the linear mixed effect model with random effects from both regions and years fit the data best, with lowest Akaike information criterion value and mean absolute error. In this model, the estimated a was 0.0192, with 95% confidence interval 0.0178~0.0308, and the estimated exponent b was 2.917 with 95% confidence interval 2.731~2.945. Estimates for a and b with the random effects in intercept and coefficient from Region and Year, ranged from 0.013 to 0.023 and from 2.835 to 3.017, respectively. Both regions and years had effects on parameters a and b, while the effects from years were shown to be much larger than those from regions. Except for Coastal Waters of Northern Shandong, a decreased from north to south. Condition factors relative to reference years of 1960, 1986, 2005, 2007, 2008~2009 and 2010 revealed that the body shape of Yellow Croaker became thinner in recent years. Furthermore relative condition factors varied among months, years, regions and length. The values of a and relative condition factors decreased, when the environmental pollution became worse, therefore, length-weight relationships could be an indicator for the environment quality. Results from this study provided basic description of current condition of Yellow Croaker along the north coast of China.

Catching What We Can't See: Manual Interception of Occluded Fly-Ball Trajectories

PubMed Central

Bosco, Gianfranco; Delle Monache, Sergio; Lacquaniti, Francesco

2012-01-01

Control of interceptive actions may involve fine interplay between feedback-based and predictive mechanisms. These processes rely heavily on target motion information available when the target is visible. However, short-term visual memory signals as well as implicit knowledge about the environment may also contribute to elaborate a predictive representation of the target trajectory, especially when visual feedback is partially unavailable because other objects occlude the visual target. To determine how different processes and information sources are integrated in the control of the interceptive action, we manipulated a computer-generated visual environment representing a baseball game. Twenty-four subjects intercepted fly-ball trajectories by moving a mouse cursor and by indicating the interception with a button press. In two separate sessions, fly-ball trajectories were either fully visible or occluded for 750, 1000 or 1250 ms before ball landing. Natural ball motion was perturbed during the descending trajectory with effects of either weightlessness (0 g) or increased gravity (2 g) at times such that, for occluded trajectories, 500 ms of perturbed motion were visible before ball disappearance. To examine the contribution of previous visual experience with the perturbed trajectories to the interception of invisible targets, the order of visible and occluded sessions was permuted among subjects. Under these experimental conditions, we showed that, with fully visible targets, subjects combined servo-control and predictive strategies. Instead, when intercepting occluded targets, subjects relied mostly on predictive mechanisms based, however, on different type of information depending on previous visual experience. In fact, subjects without prior experience of the perturbed trajectories showed interceptive errors consistent with predictive estimates of the ball trajectory based on a-priori knowledge of gravity. Conversely, the interceptive responses of subjects previously exposed to fully visible trajectories were compatible with the fact that implicit knowledge of the perturbed motion was also taken into account for the extrapolation of occluded trajectories. PMID:23166653

Catching what we can't see: manual interception of occluded fly-ball trajectories.

PubMed

Bosco, Gianfranco; Delle Monache, Sergio; Lacquaniti, Francesco

2012-01-01

Control of interceptive actions may involve fine interplay between feedback-based and predictive mechanisms. These processes rely heavily on target motion information available when the target is visible. However, short-term visual memory signals as well as implicit knowledge about the environment may also contribute to elaborate a predictive representation of the target trajectory, especially when visual feedback is partially unavailable because other objects occlude the visual target. To determine how different processes and information sources are integrated in the control of the interceptive action, we manipulated a computer-generated visual environment representing a baseball game. Twenty-four subjects intercepted fly-ball trajectories by moving a mouse cursor and by indicating the interception with a button press. In two separate sessions, fly-ball trajectories were either fully visible or occluded for 750, 1000 or 1250 ms before ball landing. Natural ball motion was perturbed during the descending trajectory with effects of either weightlessness (0 g) or increased gravity (2 g) at times such that, for occluded trajectories, 500 ms of perturbed motion were visible before ball disappearance. To examine the contribution of previous visual experience with the perturbed trajectories to the interception of invisible targets, the order of visible and occluded sessions was permuted among subjects. Under these experimental conditions, we showed that, with fully visible targets, subjects combined servo-control and predictive strategies. Instead, when intercepting occluded targets, subjects relied mostly on predictive mechanisms based, however, on different type of information depending on previous visual experience. In fact, subjects without prior experience of the perturbed trajectories showed interceptive errors consistent with predictive estimates of the ball trajectory based on a-priori knowledge of gravity. Conversely, the interceptive responses of subjects previously exposed to fully visible trajectories were compatible with the fact that implicit knowledge of the perturbed motion was also taken into account for the extrapolation of occluded trajectories.

Performance Trends During Sleep Deprivation on a Tilt-Based Control Task.

PubMed

Bolkhovsky, Jeffrey B; Ritter, Frank E; Chon, Ki H; Qin, Michael

2018-07-01

Understanding human behavior under the effects of sleep deprivation allows for the mitigation of risk due to reduced performance. To further this goal, this study investigated the effects of short-term sleep deprivation using a tilt-based control device and examined whether existing user models accurately predict targeting performance. A task in which the user tilts a surface to roll a ball into a target was developed to examine motor performance. A model was built to predict human performance for this task under various levels of sleep deprivation. Every 2 h, 10 subjects completed the task until they reached 24 h of wakefulness. Performance measurements of this task, which were based on Fitts' law, included movement time, task throughput, and time intercept. The model predicted significant performance decrements over the 24-h period with an increase in movement time (R2 = 0.61), a decrease in throughput (R2 = 0.57), and an increase in time intercept (R2 = 0.60). However, it was found that in experimental trials there was no significant change in movement time (R2 = 0.11), throughput (R2 = 0.15), or time intercept (R2 = 0.27). The results found were unexpected as performance decrement is frequently reported during sleep deprivation. These findings suggest a reexamination of the initial thought of sleep loss leading to a decrement in all aspects of performance.Bolkovsky JB, Ritter FE, Chon KH, Qin M. Performance trends during sleep deprivation on a tilt-based control task. Aerosp Med Hum Perform. 2018; 89(7):626-633.

Perceived Social Support Change in Patients with Early-stage Breast Cancer and Controls

PubMed Central

Thompson, Tess; Rodebaugh, Thomas L.; Pérez, Maria; Schootman, Mario; Jeffe, Donna B.

2014-01-01

Objective To identify variables associated with levels of and change in social support in a cohort of early-stage breast cancer patients and age-matched controls. Methods Telephone interviews measuring perceived social support and other demographic and psychosocial variables were conducted at 4–6 weeks and 6, 12, and 24 months after surgery (patients) or a normal/benign screening mammogram (controls). A latent trajectory model was used to model the intercept (starting point) and slope (changing) aspects of social support. Results Participants included 542 controls and 541 patients (77% White, 23% African American; mean age 57.7 [SD = 10.6]). Most participants reported high social support. Patients reported significantly higher levels of social support at baseline than controls. For patients, social support had a significant negative slope that significantly varied between individuals; the intercept of social support also varied significantly. Predictors of lower social support intercept in patients included not being married/partnered, being White, having lower perceived general health, and having higher negative affect (modeled as a latent variable defined by anxiety and depression symptom severity). Patients who were African American (vs. White) or had mastectomy (vs. lumpectomy) had steeper social support declines, and participants with both these characteristics had lower starting points as well as steeper declines. Social support among controls did not change significantly. Conclusions Clinicians might consider psychosocial interventions for patients reporting low social support around the time of diagnosis and surgical treatment, and for patients at risk for steeper declines in support, such as African Americans and women undergoing mastectomy. PMID:23477582

Runaway electrons and magnetic island confinement

DOE PAGES

Boozer, Allen H.

2016-08-19

The breakup of magnetic surfaces is a central feature of ITER planning for the avoidance of damage due to runaway electrons. Rapid thermal quenches, which lead to large accelerating voltages, are thought to be due to magnetic surface breakup. Impurity injection to avoid and to mitigate both halo and runaway electron currents utilizes massive gas injection or shattered pellets. The actual deposition is away from the plasma center, and the breakup of magnetic surfaces is thought to spread the effects of the impurities across the plasma cross section. The breakup of magnetic surfaces would prevent runaway electrons from reaching relativisticmore » energies were it not for the persistence of non-intercepting flux tubes. These are tubes of magnetic field lines that do not intercept the walls. In simulations and in magnetic field models, non-intercepting flux tubes are found to persist near the magnetic axis and in the cores of magnetic islands even when a large scale magnetic surface breakup occurs. As long as a few magnetic surfaces reform before all of the non-intercepting flux tubes dissipate, energetic electrons confined and accelerated in these flux tubes can serve as the seed electrons for a transfer of the overall plasma current from thermal to relativistic carriers. The acceleration of electrons is particularly strong because of the sudden changes in the poloidal flux that naturally occur in a rapid magnetic relaxation. Furthermore, the physics of magnetic islands as non-intercepting flux tubes is studied. Expressions are derived for (1) the size of islands required to confine energetic runaway electrons, (2) the accelerating electric field in an island, (3) the increase or reduction in the size of an island by the runaway electron current, (4) the approximate magnitude of the runaway current in an island, and (5) the time scale for the evolution of an island.« less

Runaway electrons and magnetic island confinement

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

Boozer, Allen H., E-mail: ahb17@columbia.edu

The breakup of magnetic surfaces is a central feature of ITER planning for the avoidance of damage due to runaway electrons. Rapid thermal quenches, which lead to large accelerating voltages, are thought to be due to magnetic surface breakup. Impurity injection to avoid and to mitigate both halo and runaway electron currents utilizes massive gas injection or shattered pellets. The actual deposition is away from the plasma center, and the breakup of magnetic surfaces is thought to spread the effects of the impurities across the plasma cross section. The breakup of magnetic surfaces would prevent runaway electrons from reaching relativisticmore » energies were it not for the persistence of non-intercepting flux tubes. These are tubes of magnetic field lines that do not intercept the walls. In simulations and in magnetic field models, non-intercepting flux tubes are found to persist near the magnetic axis and in the cores of magnetic islands even when a large scale magnetic surface breakup occurs. As long as a few magnetic surfaces reform before all of the non-intercepting flux tubes dissipate, energetic electrons confined and accelerated in these flux tubes can serve as the seed electrons for a transfer of the overall plasma current from thermal to relativistic carriers. The acceleration of electrons is particularly strong because of the sudden changes in the poloidal flux that naturally occur in a rapid magnetic relaxation. The physics of magnetic islands as non-intercepting flux tubes is studied. Expressions are derived for (1) the size of islands required to confine energetic runaway electrons, (2) the accelerating electric field in an island, (3) the increase or reduction in the size of an island by the runaway electron current, (4) the approximate magnitude of the runaway current in an island, and (5) the time scale for the evolution of an island.« less

Runaway electrons and magnetic island confinement

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

Boozer, Allen H.

The breakup of magnetic surfaces is a central feature of ITER planning for the avoidance of damage due to runaway electrons. Rapid thermal quenches, which lead to large accelerating voltages, are thought to be due to magnetic surface breakup. Impurity injection to avoid and to mitigate both halo and runaway electron currents utilizes massive gas injection or shattered pellets. The actual deposition is away from the plasma center, and the breakup of magnetic surfaces is thought to spread the effects of the impurities across the plasma cross section. The breakup of magnetic surfaces would prevent runaway electrons from reaching relativisticmore » energies were it not for the persistence of non-intercepting flux tubes. These are tubes of magnetic field lines that do not intercept the walls. In simulations and in magnetic field models, non-intercepting flux tubes are found to persist near the magnetic axis and in the cores of magnetic islands even when a large scale magnetic surface breakup occurs. As long as a few magnetic surfaces reform before all of the non-intercepting flux tubes dissipate, energetic electrons confined and accelerated in these flux tubes can serve as the seed electrons for a transfer of the overall plasma current from thermal to relativistic carriers. The acceleration of electrons is particularly strong because of the sudden changes in the poloidal flux that naturally occur in a rapid magnetic relaxation. Furthermore, the physics of magnetic islands as non-intercepting flux tubes is studied. Expressions are derived for (1) the size of islands required to confine energetic runaway electrons, (2) the accelerating electric field in an island, (3) the increase or reduction in the size of an island by the runaway electron current, (4) the approximate magnitude of the runaway current in an island, and (5) the time scale for the evolution of an island.« less

Climbing plants in a temperate rainforest understorey: searching for high light or coping with deep shade?

PubMed Central

Valladares, Fernando; Gianoli, Ernesto; Saldaña, Alfredo

2011-01-01

Background and Aims While the climbing habit allows vines to reach well-lit canopy areas with a minimum investment in support biomass, many of them have to survive under the dim understorey light during certain stages of their life cycle. But, if the growth/survival trade-off widely reported for trees hold for climbing plants, they cannot maximize both light-interception efficiency and shade avoidance (i.e. escaping from the understorey). The seven most important woody climbers occurring in a Chilean temperate evergreen rainforest were studied with the hypothesis that light-capture efficiency of climbers would be positively associated with their abundance in the understorey. Methods Species abundance in the understorey was quantified from their relative frequency and density in field plots, the light environment was quantified by hemispherical photography, the photosynthetic response to light was measured with portable gas-exchange analyser, and the whole shoot light-interception efficiency and carbon gain was estimated with the 3-D computer model Y-plant. Key Results Species differed in specific leaf area, leaf mass fraction, above ground leaf area ratio, light-interception efficiency and potential carbon gain. Abundance of species in the understorey was related to whole shoot features but not to leaf level features such as specific leaf area. Potential carbon gain was inversely related to light-interception efficiency. Mutual shading among leaves within a shoot was very low (<20 %). Conclusions The abundance of climbing plants in this southern rainforest understorey was directly related to their capacity to intercept light efficiently but not to their potential carbon gain. The most abundant climbers in this ecosystem match well with a shade-tolerance syndrome in contrast to the pioneer-like nature of climbers observed in tropical studies. The climbers studied seem to sacrifice high-light searching for coping with the dim understorey light. PMID:21685433

A reprogrammable receiver architecture for wireless signal interception

NASA Astrophysics Data System (ADS)

Yao, Timothy S.

2003-09-01

In this paper, a re-programmable receiver architecture, based on software-defined-radio concept, for wireless signal interception is presented. The radio-frequency (RF) signal that the receiver would like to intercept may come from a terrestrial cellular network or communication satellites, which their carrier frequency are in the range from 800 MHz (civilian mobile) to 15 GHz (Ku band). To intercept signals from such a wide range of frequency in these variant communication systems, the traditional way is to deploy multiple receivers to scan and detect the desired signal. This traditional approach is obviously unattractive due to the cost, efficiency, and accuracy. Instead, we propose a universal receiver, which is software-driven and re-configurable, to intercept signals of interest. The software-defined-radio based receiver first intercepts RF energy of wide spectrum (25MHz) through antenna, performs zero-IF down conversion (homodyne architecture) to baseband, and digital channelizes the baseband signal. The channelization module is a bank of high performance digital filters. The bandwidth of the filter bank is programmable according to the wireless communication protocol under watch. In the baseband processing, high-performance digital signal processors carry out the detection process and microprocessors handle the communication protocols. The baseband processing is also re-configurable for different wireless standards and protocol. The advantages of the software-defined-radio architecture over traditional RF receiver make it a favorable technology for the communication signal interception and surveillance.

Comparison of the chemical evolution and characteristics of 495 biomass burning plumes intercepted by the NASA DC-8 aircraft during the ARCTAS/CARB-2008 field campaign

NASA Astrophysics Data System (ADS)

Hecobian, A.; Liu, Z.; Hennigan, C. J.; Huey, L. G.; Jimenez, J. L.; Cubison, M. J.; Vay, S.; Diskin, G. S.; Sachse, G. W.; Wisthaler, A.; Mikoviny, T.; Weinheimer, A. J.; Liao, J.; Knapp, D. J.; Wennberg, P. O.; Kürten, A.; Crounse, J. D.; St. Clair, J.; Wang, Y.; Weber, R. J.

2011-06-01

This paper compares measurements of gaseous and particulate emissions from a wide range of biomass-burning plumes intercepted by the NASA DC-8 research aircraft during the three phases of the ARCTAS-2008 experiment: ARCTAS-A, based out of Fairbanks, Alaska USA (3 April to 19 April 2008); ARCTAS-B based out of Cold Lake, Alberta, Canada (29 June to 13 July 2008); and ARCTAS-CARB, based out of Palmdale, California, USA (18 June to 24 June 2008). Extensive investigations of boreal fire plume evolution were undertaken during ARCTAS-B, where four distinct fire plumes that were intercepted by the aircraft over a range of down-wind distances (0.1 to 16 hr transport times) were studied in detail. Based on these analyses, there was no evidence for ozone production and a box model simulation of the data confirmed that net ozone production was slow (on average 1 ppbv h-1 in the first 3 h and much lower afterwards) due to limited NOx. Peroxyacetyl nitrate concentrations (PAN) increased with plume age and the box model estimated an average production rate of ~80 pptv h-1 in the first 3 h. Like ozone, there was also no evidence for net secondary inorganic or organic aerosol formation. There was no apparent increase in aerosol mass concentrations in the boreal fire plumes due to secondary organic aerosol (SOA) formation; however, there were indications of chemical processing of the organic aerosols. In addition to the detailed studies of boreal fire plume evolution, about 500 smoke plumes intercepted by the NASA DC-8 aircraft were segregated by fire source region. The normalized excess mixing ratios (i.e. ΔX/ΔCO) of gaseous (carbon dioxide, acetonitrile, hydrogen cyanide, toluene, benzene, methane, oxides of nitrogen (NOx), ozone, PAN) and fine aerosol particulate components (nitrate, sulfate, ammonium, chloride, organic aerosols and water soluble organic carbon) of these plumes were compared.

Gaze Behaviour during Interception in Children with Spastic Unilateral Cerebral Palsy

ERIC Educational Resources Information Center

van Kampen, P. M.; Ledebt, A.; Smorenburg, A. R. P.; Vermeulen, R. J.; Kelder, M. E.; van der Kamp, J.; Savelsbergh, G. J. P.

2012-01-01

Anticipatory gaze behaviour during interceptive movements was investigated in children with Spastic Unilateral Cerebral Palsy (SUCP), and related to the side of the intracerebral lesion. Five children with lesions of the right hemisphere (RHL) and five children with lesions of the left hemisphere (LHL) had to walk towards and intercept a ball that…

Snow catch by conifer crowns

Treesearch

Donald R. Satterlund; Harold F. Haupt

1967-01-01

Study of interception storage of snow by two species of sapling conifers in northern Idaho revealed that cumulative snow catch follows the classical law of autocatakinetic growth, or [equation - see PDF] where I, is interception storage, e is the interception storage capacity of the tree, e is the base of the natural logarithm, k is a constant expressing the rate of...

Description and Initial Evaluation of a Computer-Based Individual Trainer for the Radar Intercept Observer.

ERIC Educational Resources Information Center

Rigney, Joseph W.; And Others

An individual trainer for giving students in the radar intercept observer (RIO) schools concentrated practice in procedures for air-to-air intercepts was designed around a programmable graphics terminal with two integral minicomputers and 8k of core memory. The trainer automatically administers practice in computing values of variables in the…

Rainfall interception by annual grass and chaparral . . . losses compared

Treesearch

Edward S. Corbett; Robert P. Crouse

1968-01-01

Loss of precipitation due to interception by annual grass and grass litter was measured during three rainy seasons on the San Dimas Experimental Forest, in southern California. Interception loss from annual grass averaged 7.9 percent; that from mature chaparral cover, 12.8 percent. If chaparral stands were converted to grass, an estimated 1.3 inches of gross...

Estimating Water Storage Capacity of Existing and Potentially Restorable Wetland Depressions in a Subbasin of the Red River of the North

USGS Publications Warehouse

Gleason, Robert A.; Tangen, Brian A.; Laubhan, Murray K.; Kermes, Kevin E.; Euliss, Ned H.

2007-01-01

Executive Summary Concern over flooding along rivers in the Prairie Pothole Region has stimulated interest in developing spatially distributed hydrologic models to simulate the effects of wetland water storage on peak river flows. Such models require spatial data on the storage volume and interception area of existing and restorable wetlands in the watershed of interest. In most cases, information on these model inputs is lacking because resolution of existing topographic maps is inadequate to estimate volume and areas of existing and restorable wetlands. Consequently, most studies have relied on wetland area to volume or interception area relationships to estimate wetland basin storage characteristics by using available surface area data obtained as a product from remotely sensed data (e.g., National Wetlands Inventory). Though application of areal input data to estimate volume and interception areas is widely used, a drawback is that there is little information available to provide guidance regarding the application, limitations, and biases associated with such approaches. Another limitation of previous modeling efforts is that water stored by wetlands within a watershed is treated as a simple lump storage component that is filled prior to routing overflow to a pour point or gaging station. This approach does not account for dynamic wetland processes that influence water stored in prairie wetlands. Further, most models have not considered the influence of human-induced hydrologic changes, such as land use, that greatly influence quantity of surface water inputs and, ultimately, the rate that a wetland basin fills and spills. The goals of this study were to (1) develop and improve methodologies for estimating and spatially depicting wetland storage volumes and interceptions areas and (2) develop models and approaches for estimating/simulating the water storage capacity of potentially restorable and existing wetlands under various restoration, land use, and climatic scenarios. To address these goals, we developed models and approaches to spatially represent storage volumes and interception areas of existing and potentially restorable wetlands in the upper Mustinka subbasin within Grant County, Minn. We then developed and applied a model to simulate wetland water storage increases that would result from restoring 25 and 50 percent of the farmed and drained wetlands in the upper Mustinka subbasin. The model simulations were performed during the growing season (May-October) for relatively wet (1993; 0.79 m of precipitation) and dry (1987; 0.40 m of precipitation) years. Results from the simulations indicated that the 25 percent restoration scenario would increase water storage by 21-24 percent and that a 50 percent scenario would increase storage by 34-38 percent. Additionally, we estimated that wetlands in the subbasin have potential to store 11.57-20.98 percent of the total precipitation that fell over the entire subbasin area (52,758 ha). Our simulation results indicated that there is considerable potential to enhance water storage in the subbasin; however, evaluation and calibration of the model is necessary before simulation results can be applied to management and planning decisions. In this report we present guidance for the development and application of models (e.g., surface area-volume predictive models, hydrology simulation model) to simulate wetland water storage to provide a basis from which to understand and predict the effects of natural or human-induced hydrologic alterations. In developing these approaches, we tried to use simple and widely available input data to simulate wetland hydrology and predict wetland water storage for a specific precipitation event or a series of events. Further, the hydrology simulation model accounted for land use and soil type, which influence surface water inputs to wetlands. Although information presented in this report is specific to the Mustinka subbasin, the approaches

Canopy water balance of windward and leeward Hawaiian cloud forests on Haleakalā, Maui, Hawai'i

USGS Publications Warehouse

Giambelluca, Thomas W.; DeLay, John K.; Nullet, Michael A.; Scholl, Martha A.; Gingerich, Stephen B.

2011-01-01

The contribution of intercepted cloud water to precipitation at windward and leeward cloud forest sites on the slopes of Haleakalā, Maui was assessed using two approaches. Canopy water balance estimates based on meteorological monitoring were compared with interpretations of fog screen measurements collected over a 2-year period at each location. The annual incident rainfall was 973 mm at the leeward site (Auwahi) and 2550 mm at the windward site (Waikamoi). At the leeward, dry forest site, throughfall was less than rainfall (87%), and, at the windward, wet forest site, throughfall exceeded rainfall (122%). Cloud water interception estimated from canopy water balance was 166 mm year−1 at Auwahi and 1212 mm year−1 at Waikamoi. Annual fog screen measurements of cloud water flux, corrected for wind-blown rainfall, were 132 and 3017 mm for the dry and wet sites respectively. Event totals of cloud water flux based on fog screen measurements were poorly correlated with event cloud water interception totals derived from the canopy water balance. Hence, the use of fixed planar fog screens to estimate cloud water interception is not recommended. At the wet windward site, cloud water interception made up 32% of the total precipitation, adding to the already substantial amount of rainfall. At the leeward dry site, cloud water interception was 15% of the total precipitation. Vegetation at the dry site, where trees are more exposed and isolated, was more efficient at intercepting the available cloud water than at the rainy site, but events were less frequent, shorter in duration and lower in intensity. A large proportion of intercepted cloud water, 74% and 83%, respectively for the two sites, was estimated to become throughfall, thus adding significantly to soil water at both sites

Study on Hydrological Functions of Litter Layers in North China

PubMed Central

Li, Xiang; Niu, Jianzhi; Xie, Baoyuan

2013-01-01

Canopy interception, throughfall, stemflow, and runoff have received considerable attention during the study of water balance and hydrological processes in forested ecosystems. Past research has either neglected or underestimated the role of hydrological functions of litter layers, although some studies have considered the impact of various characteristics of rainfall and litter on litter interception. Based on both simulated rainfall and litter conditions in North China, the effect of litter mass, rainfall intensity and litter type on the maximum water storage capacity of litter (S) and litter interception storage capacity (C) were investigated under five simulated rainfall intensities and four litter masses for two litter types. The results indicated: 1) the S values increased linearly with litter mass, and the S values of broadleaf litter were on average 2.65 times larger than the S values of needle leaf litter; 2) rainfall intensity rather than litter mass determined the maximum interception storage capacity (Cmax); Cmax increased linearly with increasing rainfall intensity; by contrast, the minimum interception storage capacity (Cmin) showed a linear relationship with litter mass, but a poor correlation with rainfall intensity; 3) litter type impacted Cmax and Cmin; the values of Cmax and Cmin for broadleaf litter were larger than those of needle leaf litter, which indicated that broadleaf litter could intercepte and store more water than needle leaf litter; 4) a gap existed between Cmax and Cmin, indicating that litter played a significant role by allowing rainwater to infiltrate or to produce runoff rather than intercepting it and allowing it to evaporate after the rainfall event; 5) Cmin was always less than S at the same litter mass, which should be considered in future interception predictions. Vegetation and precipitation characteristics played important roles in hydrological characteristics. PMID:23936188

Opportunities for ballistic missions to Halley's comet

NASA Technical Reports Server (NTRS)

Farquhar, R. W.; Wooden, W. H., II

1977-01-01

Alternative strategies for ballistic missions to Halley's comet in 1985-86 are described. It is shown that a large science return would be acquired from a ballistic Halley intercept in spite of the high flyby speeds of almost 60 km/sec that are associated with this mission mode. The possibility of retargeting the cometary spacecraft to additional comets after the Halley intercept also exists. In one scenario two cometary spacecraft of identical design would be used to carry out four separate cometary encounters over a three-year period. One spacecraft would intercept Halley before its perihelion passage in December 1985 and then go on to comet Borrelly witn an encounter in January 1988. The other spacecraft would be targeted for a post-perihelion Halley intercept in March 1986 before proceeding towards an encounter with comet Tempel-2 in September 1988. The flyby speeds for the Borrelly and Tempel-2 intercepts are 21 and 13 km/sec, respectively.

Analysis of Multimode Low-Probability-of-Intercept (LPI) Communications With Atmospheric Effects

DTIC Science & Technology

1996-12-01

of the Requirements for the Degree of Master of Science in Electrical Engineering Ala Ghordlo, B.ENG Captain, Royal Jordanian Air Force December...2-10 2.1.3.5 Atmospheric Quality Factor ............... 2-10 2.2 Propagation Models And Atmospheric Models ............ 2-12 2.2.1 The...Hata Model .............................. 2-12 2.2.2 The MPM Model ....... ...................... 2-13 2.2.3 Discussion of M odels .................... 2

Is religiosity positively associated with school connectedness: evidence from high school students in Atlantic Canada?

PubMed

Azagba, Sunday; Asbridge, Mark; Langille, Donald B

2014-12-01

School connectedness (SC) is associated with decreased student risk behavior and better health and social outcomes. While a considerable body of research has examined the factors associated with SC, there is limited evidence about the particular role of religiosity in shaping levels of SC. Employing data reported by junior and senior high school students from Atlantic Canada, this study examines whether religiosity is positively associated with SC and whether such associations differ by gender. We tested the association between SC and religiosity using a random intercept multilevel logistic regression. The between-school variability in SC was first determined by our estimating a null or empty model; three different model specifications that included covariates were estimated: in Model 1 we adjusted for gender, age, academic performance, parental education, and living arrangement; in Model 2 for sensation seeking and subjective social status in addition to Model 1 variables; and in Model 3 we added substance use to the analysis. Our multilevel regression analyses showed that religiosity was protectively associated with lower SC across the three model specifications when both genders were examined together. In gender-stratified analyses we found similar protective associations of religiosity, with lower SC for both males and females in all three models. Given the overwhelming positive impact of SC on a range of health, social and school outcomes, it is important to understand the role of religiosity, among other factors, that may be modified to enhance student's connectedness to school.

Assessing Omitted Confounder Bias in Multilevel Mediation Models.

PubMed

Tofighi, Davood; Kelley, Ken

2016-01-01

To draw valid inference about an indirect effect in a mediation model, there must be no omitted confounders. No omitted confounders means that there are no common causes of hypothesized causal relationships. When the no-omitted-confounder assumption is violated, inference about indirect effects can be severely biased and the results potentially misleading. Despite the increasing attention to address confounder bias in single-level mediation, this topic has received little attention in the growing area of multilevel mediation analysis. A formidable challenge is that the no-omitted-confounder assumption is untestable. To address this challenge, we first analytically examined the biasing effects of potential violations of this critical assumption in a two-level mediation model with random intercepts and slopes, in which all the variables are measured at Level 1. Our analytic results show that omitting a Level 1 confounder can yield misleading results about key quantities of interest, such as Level 1 and Level 2 indirect effects. Second, we proposed a sensitivity analysis technique to assess the extent to which potential violation of the no-omitted-confounder assumption might invalidate or alter the conclusions about the indirect effects observed. We illustrated the methods using an empirical study and provided computer code so that researchers can implement the methods discussed.

Ground Contact Modeling for the Morpheus Test Vehicle Simulation

NASA Technical Reports Server (NTRS)

Cordova, Luis

2014-01-01

The Morpheus vertical test vehicle is an autonomous robotic lander being developed at Johnson Space Center (JSC) to test hazard detection technology. Because the initial ground contact simulation model was not very realistic, it was decided to improve the model without making it too computationally expensive. The first development cycle added capability to define vehicle attachment points (AP) and to keep track of their states in the lander reference frame (LFRAME). These states are used with a spring damper model to compute an AP contact force. The lateral force is then overwritten, if necessary, by the Coulomb static or kinetic friction force. The second development cycle added capability to use the PolySurface class as the contact surface. The class can load CAD data in STL (Stereo Lithography) format, and use the data to compute line of sight (LOS) intercepts. A polygon frame (PFRAME) is computed from the facet intercept normal and used to convert the AP state to PFRAME. Three flat plane tests validate the transitions from kinetic to static, static to kinetic, and vertical impact. The hazardous terrain test will be used to test for visual reasonableness. The improved model is numerically inexpensive, robust, and produces results that are reasonable.

Ground Contact Modeling for the Morpheus Test Vehicle Simulation

NASA Technical Reports Server (NTRS)

Cordova, Luis

2013-01-01

The Morpheus vertical test vehicle is an autonomous robotic lander being developed at Johnson Space Center (JSC) to test hazard detection technology. Because the initial ground contact simulation model was not very realistic, it was decided to improve the model without making it too computationally expensive. The first development cycle added capability to define vehicle attachment points (AP) and to keep track of their states in the lander reference frame (LFRAME). These states are used with a spring damper model to compute an AP contact force. The lateral force is then overwritten, if necessary, by the Coulomb static or kinetic friction force. The second development cycle added capability to use the PolySurface class as the contact surface. The class can load CAD data in STL (Stereo Lithography) format, and use the data to compute line of sight (LOS) intercepts. A polygon frame (PFRAME) is computed from the facet intercept normal and used to convert the AP state to PFRAME. Three flat plane tests validate the transitions from kinetic to static, static to kinetic, and vertical impact. The hazardous terrain test will be used to test for visual reasonableness. The improved model is numerically inexpensive, robust, and produces results that are reasonable.

Global environmental effects of impact-generated aerosols: Results from a general circulation model

NASA Technical Reports Server (NTRS)

Covey, Curt; Ghan, Steven J.; Walton, John J.; Weissman, Paul R.

1989-01-01

Interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet would lead to substantial land surface cooling, according to the three-dimensional atmospheric general circulation model (GCM). This result is qualitatively similar to conclusions drawn from an earlier study that employed a one-dimensional atmospheric model, but in the GCM simulation the heat capacity of the oceans, not included in the one-dimensional model, substantially mitigates land surface cooling. On the other hand, the low heat capacity of the GCM's land surface allows temperatures to drop more rapidly in the initial stages of cooling than in the one-dimensional model study. GCM-simulated climatic changes in the scenario of asteroid/comet winter are more severe than in nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on earth. Impacts of smaller objects could also lead to dramatic, though of course less severe, climatic changes, according to the GCM. An asteroid or comet impact would not lead to anything approaching complete global freezing, but quite reasonable to assume that impacts would dramatically alter the climate in at least a patchy sense.

A New High-Resolution Direction Finding Architecture Using Photonics and Neural Network Signal Processing for Miniature Air Vehicle Applications

DTIC Science & Technology

2015-09-01

3 4. Probability of Intercept .................................................................3 5. Superresolution ...intercept. This alignment gives the shortest mean-time-to-intercept and can be less than one second. 4 5. Superresolution For single signals...at each antenna element. For multiple signals, superresolution DF techniques are often used. These techniques can be broken down into beamforming

Growth in relation to canopy light interception in a red pine (Pinus resinosa) thinning study

Treesearch

Beverly E. Law; Kurt H. Riitters; Lewis F. Ohmann

1992-01-01

Growth data from the most recent 5 years of a 40-year thinning study in an even-aged red pine (Pinus resinosa) forest in cutfoot sioux experimental forest, Minnesota, were used with intercepted photosynthetically active radiation (IPAR) data to determine the relationship between light interception and growth for a range ofstand densities. Stand basal...

Interception of precipitation by northern hardwoods

Treesearch

Raymond E. Leonard

1961-01-01

When forest watershed management research was begun at the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire in 1955, we felt certain that at least one aspect of hydrology would not require study-interception. Interception has been studied for a long time, in fact, as early as 1889 (Horton, 1919). It has been well known that a certain amount of...

Intercepted Scolytidae (Coleoptera) at U.S. ports of entry: 1985-2000.

Treesearch

Robert A. Haack

2001-01-01

Since 1985, the U.S. Department of Agriculture, Animal and Plant Health Inspection Service has maintained the 'Port Information Network' (PIN) database for plant pests intercepted at the U.S. ports of entry. As of August 2001, PIN contained 6825 records of beetles (Coleoptera) in the family Scolytidae that had been intercepted during the years 1985-2000 from...

A Primer on the Statistical Modelling of Learning Curves in Health Professions Education

ERIC Educational Resources Information Center

Pusic, Martin V.; Boutis, Kathy; Pecaric, Martin R.; Savenkov, Oleksander; Beckstead, Jason W.; Jaber, Mohamad Y.

2017-01-01

Learning curves are a useful way of representing the rate of learning over time. Features include an index of baseline performance (y-intercept), the efficiency of learning over time (slope parameter) and the maximal theoretical performance achievable (upper asymptote). Each of these parameters can be statistically modelled on an individual and…

Estimating Canopy Dark Respiration for Crop Models

NASA Technical Reports Server (NTRS)

Monje Mejia, Oscar Alberto

2014-01-01

Crop production is obtained from accurate estimates of daily carbon gain.Canopy gross photosynthesis (Pgross) can be estimated from biochemical models of photosynthesis using sun and shaded leaf portions and the amount of intercepted photosyntheticallyactive radiation (PAR).In turn, canopy daily net carbon gain can be estimated from canopy daily gross photosynthesis when canopy dark respiration (Rd) is known.

Effects of Barbell Deadlift Training on Submaximal Motor Unit Firing Rates for the Vastus Lateralis and Rectus Femoris

PubMed Central

Stock, Matt S.; Thompson, Brennan J.

2014-01-01

Previous investigations that have studied motor unit firing rates following strength training have been limited to small muscles, isometric training, or interventions involving exercise machines. We examined the effects of ten weeks of supervised barbell deadlift training on motor unit firing rates for the vastus lateralis and rectus femoris during a 50% maximum voluntary contraction (MVC) assessment. Twenty-four previously untrained men (mean age  = 24 years) were randomly assigned to training (n = 15) or control (n = 9) groups. Before and following the intervention, the subjects performed isometric testing of the right knee extensors while bipolar surface electromyographic signals were detected from the two muscles. The signals were decomposed into their constituent motor unit action potential trains, and motor units that demonstrated accuracy levels less than 92.0% were not considered for analysis. One thousand eight hundred ninety-two and 2,013 motor units were examined for the vastus lateralis and rectus femoris, respectively. Regression analyses were used to determine the linear slope coefficients (pulses per second [pps]/% MVC) and y-intercepts (pps) of the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. Deadlift training significantly improved knee extensor MVC force (Cohen's d = .70), but did not influence force steadiness. Training had no influence on the slopes and y-intercepts for the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. In agreement with previous cross-sectional comparisons and randomized control trials, our findings do not support the notion that strength training affects the submaximal control of motor units. PMID:25531294

Experimental evidence for negative turgor pressure in small leaf cells of Robinia pseudoacacia L versus large cells of Metasequoia glyptostroboides Hu et W.C. Cheng. 2. Höfler diagrams below the volume of zero turgor and the theoretical implication for pressure-volume curves of living cells.

PubMed

Yang, Dongmei; Li, Junhui; Ding, Yiting; Tyree, Melvin T

2017-03-01

The physiological advantages of negative turgor pressure, P t , in leaf cells are water saving and homeostasis of reactants. This paper advances methods for detecting the occurrence of negative P t in leaves. Biomechanical models of pressure-volume (PV) curves predict that negative P t does not change the linearity of PV curve plots of inverse balance pressure, P B , versus relative water loss, but it does predict changes in either the y-intercept or the x-intercept of the plots depending on where cell collapse occurs in the P B domain because of negative P t . PV curve analysis of Robinia leaves revealed a shift in the x-intercept (x-axis is relative water loss) of PV curves, caused by negative P t of palisade cells. The low x-intercept of the PV curve was explained by the non-collapse of palisade cells in Robinia in the P B domain. Non-collapse means that P t smoothly falls from positive to negative values with decreasing cell volume without a dramatic change in slope. The magnitude of negative turgor in non-collapsing living cells was as low as -1.3 MPa and the relative volume of the non-collapsing cell equaled 58% of the total leaf cell volume. This study adds to the growing evidence for negative P t . © 2016 John Wiley & Sons Ltd.

When hawks attack: animal-borne video studies of goshawk pursuit and prey-evasion strategies

PubMed Central

Kane, Suzanne Amador; Fulton, Andrew H.; Rosenthal, Lee J.

2015-01-01

Video filmed by a camera mounted on the head of a Northern Goshawk (Accipiter gentilis) was used to study how the raptor used visual guidance to pursue prey and land on perches. A combination of novel image analysis methods and numerical simulations of mathematical pursuit models was used to determine the goshawk's pursuit strategy. The goshawk flew to intercept targets by fixing the prey at a constant visual angle, using classical pursuit for stationary prey, lures or perches, and usually using constant absolute target direction (CATD) for moving prey. Visual fixation was better maintained along the horizontal than vertical direction. In some cases, we observed oscillations in the visual fix on the prey, suggesting that the goshawk used finite-feedback steering. Video filmed from the ground gave similar results. In most cases, it showed goshawks intercepting prey using a trajectory consistent with CATD, then turning rapidly to attack by classical pursuit; in a few cases, it showed them using curving non-CATD trajectories. Analysis of the prey's evasive tactics indicated that only sharp sideways turns caused the goshawk to lose visual fixation on the prey, supporting a sensory basis for the surprising frequency and effectiveness of this tactic found by previous studies. The dynamics of the prey's looming image also suggested that the goshawk used a tau-based interception strategy. We interpret these results in the context of a concise review of pursuit–evasion in biology, and conjecture that some prey deimatic ‘startle’ displays may exploit tau-based interception. PMID:25609783

Neighbourhood social capital and adolescent self-reported wellbeing in New Zealand: a multilevel analysis.

PubMed

Aminzadeh, Kaveh; Denny, Simon; Utter, Jennifer; Milfont, Taciano L; Ameratunga, Shanthi; Teevale, Tasileta; Clark, Terryann

2013-05-01

The association between neighbourhood social capital and individual health and wellbeing has been explored mainly by focussing on adult outcomes. This study explores the relationship between neighbourhood social capital and adolescent subjective wellbeing, and its interaction with adolescents' socioeconomic status. Data was taken from a random sample of 9107 students who participated in a nationally representative health survey of high school students in New Zealand in 2007. Students' wellbeing was measured by questions on general mood, life satisfaction and WHO-5 Wellbeing Index. Neighbourhood social capital was assessed according to five indicators: neighbourhood social cohesion, facilities, physical disintegration, membership in community organisations, and residential stability. All neighbourhood measures were created based on students' responses aggregated to the neighbourhood level. Neighbourhood was defined as a Census Area Unit, with a median population of 2000 people. Analyses included only neighbourhoods with more than 10 students, and were conducted using cross-classified random intercept multilevel models controlling for students' age, sex, ethnicity and socioeconomic status, with both schools and neighbourhoods treated as random effects. A total of 5567 students within 262 neighbourhoods were considered in the analysis. Students living in neighbourhoods characterised by higher levels of social cohesion and membership in community organisations reported higher levels of wellbeing. The association between student self-reported wellbeing and neighbourhood membership in community organisations varied according to the individual socioeconomic status of students. Neighbourhood membership in community organisations showed a stronger protective effect for students who were more socioeconomically deprived. Copyright © 2013 Elsevier Ltd. All rights reserved.

Children's negative emotions and ego-resiliency: longitudinal relations with social competence.

PubMed

Taylor, Zoe E; Eisenberg, Nancy; VanSchyndel, Sarah K; Eggum-Wilkens, Natalie D; Spinrad, Tracy L

2014-04-01

We examined the relations of negative emotions in toddlerhood to the development of ego-resiliency and social competence across early childhood. Specifically, we addressed whether fear and anger/frustration in 30-month-old children (N = 213) was associated with the development of ego-resiliency across 4 time points (42 to 84 months), and, in turn, whether ego-resiliency predicted social competence at 84 months. Child anger/frustration negatively predicted the intercept of ego-resiliency at 42 months (controlling for prior ego-resiliency at 18 months) as well as the slope. Fear did not significantly predict either the intercept or slope of ego-resiliency in the structural model, although it was positively correlated with anger/frustration and was negatively related to ego-resiliency in zero-order correlations. The slope of ego-resiliency was positively related to children's social competence at 84 months; however, the intercept of ego-resiliency (set at 42 months) was not a significant predictor of later social competence. Furthermore, the slope of ego-resiliency mediated the relations between anger/frustration and children's later social competence. The results suggest that individual differences in anger/frustration might contribute to the development of ego-resiliency, which, in turn, is associated with children's social competence.

Etiology of Stability and Growth of Internalizing and Externalizing Behavior Problems Across Childhood and Adolescence.

PubMed

Hatoum, Alexander S; Rhee, Soo Hyun; Corley, Robin P; Hewitt, John K; Friedman, Naomi P

2018-04-20

Internalizing and externalizing behaviors are heritable, and show genetic stability during childhood and adolescence. Less work has explored how genes influence individual differences in developmental trajectories. We estimated ACE biometrical latent growth curve models for the Teacher Report Form (TRF) and parent Child Behavior Checklist (CBCL) internalizing and externalizing scales from ages 7 to 16 years in 408 twin pairs from the Colorado Longitudinal Twin Study. We found that Intercept factors were highly heritable for both internalizing and externalizing behaviors (a2 = .61-.92), with small and nonsignificant environmental influences for teacher-rated data but significant nonshared environmental influences for parent-rated data. There was some evidence of heritability of decline in internalizing behavior (Slopes for teacher and parent ratings), but the Slope genetic variance was almost entirely shared with that for the Intercept when different than zero. These results suggest that genetic effects on these developmental trajectories operate primarily on initial levels and stability, with no significant unique genetic influences for change. Finally, cross-rater analyses of the growth factor scores revealed moderate to large genetic and environmental associations between growth factors derived from parents' and teachers' ratings, particularly the Intercepts.

Modeling Rainfall-Runoff Dynamics in Tropical, Urban Socio-Hydrological Systems: Green Infrastructure and Variable Precipitation Interception

NASA Astrophysics Data System (ADS)

Nytch, C. J.; Meléndez-Ackerman, E. J.

2014-12-01

There is a pressing need to generate spatially-explicit models of rainfall-runoff dynamics in the urban humid tropics that can characterize flow pathways and flood magnitudes in response to erratic precipitation events. To effectively simulate stormwater runoff processes at multiple scales, complex spatio-temporal parameters such as rainfall, evapotranspiration, and antecedent soil moisture conditions must be accurately represented, in addition to uniquely urban factors including stormwater conveyance structures and connectivity between green and gray infrastructure elements. In heavily urbanized San Juan, Puerto Rico, stream flashiness and frequent flooding are major issues, yet still lacking is a hydrological analysis that models the generation and movement of fluvial and pluvial stormwater through the watershed. Our research employs a novel and multifaceted approach to dealing with this problem that integrates 1) field-based rainfall interception and infiltration methodologies to quantify the hydrologic functions of natural and built infrastructure in San Juan; 2) remote sensing analysis to produce a fine-scale typology of green and gray cover types in the city and determine patterns of spatial distribution and connectivity; 3) assessment of precipitation and streamflow variability at local and basin-wide scales using satellite and radar precipitation estimates in concert with rainfall and stream gauge point data and participatory flood mapping; 4) simulation of historical, present-day, and future stormwater runoff scenarios with a fully distributed hydrologic model that couples diverse components of urban socio-hydrological systems from formal and informal knowledge sources; and 5) bias and uncertainty analysis of parameters and model structure within a Bayesian hierarchical framework. Preliminary results from the rainfall interception study suggest that canopy structure and leaf area index of different tree species contribute to variable throughfall and stemflow responses. Additional investigations are pending. The findings from this work will help inform urban planning and design, and build adaptive capacity to reduce flood vulnerability in the context of a changing climate.

Linking ice accretion and crown structure: towards a model of the effect of freezing rain on tree canopies

PubMed Central

Nock, Charles A.; Lecigne, Bastien; Taugourdeau, Olivier; Greene, David F.; Dauzat, Jean; Delagrange, Sylvain; Messier, Christian

2016-01-01

Background and Aims Despite a longstanding interest in variation in tree species vulnerability to ice storm damage, quantitative analyses of the influence of crown structure on within-crown variation in ice accretion are rare. In particular, the effect of prior interception by higher branches on lower branch accumulation remains unstudied. The aim of this study was to test the hypothesis that intra-crown ice accretion can be predicted by a measure of the degree of sheltering by neighbouring branches. Methods Freezing rain was artificially applied to Acer platanoides L., and in situ branch-ice thickness was measured directly and from LiDAR point clouds. Two models of freezing rain interception were developed: ‘IceCube’, which uses point clouds to relate ice accretion to a voxel-based index (sheltering factor; SF) of the sheltering effect of branch elements above a measurement point; and ‘IceTree’, a simulation model for in silico evaluation of the interception pattern of freezing rain in virtual tree crowns. Key Results Intra-crown radial ice accretion varied strongly, declining from the tips to the bases of branches and from the top to the base of the crown. SF for branches varied strongly within the crown, and differences among branches were consistent for a range of model parameters. Intra-crown variation in ice accretion on branches was related to SF (R2 = 0·46), with in silico results from IceTree supporting empirical relationships from IceCube. Conclusions Empirical results and simulations confirmed a key role for crown architecture in determining intra-crown patterns of ice accretion. As suspected, the concentration of freezing rain droplets is attenuated by passage through the upper crown, and thus higher branches accumulate more ice than lower branches. This is the first step in developing a model that can provide a quantitative basis for investigating intra-crown and inter-specific variation in freezing rain damage. PMID:27107412

SHIIVER (Structural Heat Intercept Insulation Vibration Evaluation Rig)

NASA Image and Video Library

2017-06-11

SHIIVER Tank Arrives at NASA’s Marshall Center for Spray-On Foam InsulationSHIIVER (Structural Heat Intercept Insulation Vibration Evaluation Rig) is a cryogenic test tank developed to evaluate heat intercept concepts. It arrived at Marshall Space Flight Center on August 10, 2017. The tank will receive heat sensors and spray-on foam insulation before making its way to Plum Brook station for further insulation and testing.

SHIIVER (Structural Heat Intercept Insulation Vibration Evaluation Rig)

NASA Image and Video Library

2017-06-11

SHIIVER (Structural Heat Intercept Insulation Vibration Evaluation Rig) is a cryogenic test tank developed to evaluate heat intercept concepts. It arrived at Marshall Space Flight Center on August 10, 2017. The tank will receive heat sensors and spray-on foam insulation before making its way to Plum Brook station for further insulation and testing.SHIIVER Tank Arrives at NASA’s Marshall Center for Spray-On Foam Insulation

Quadrotor Intercept Trajectory Planning and Simulation

DTIC Science & Technology

2017-06-01

Figure 41. Results are grouped by geometry type and colored based on trajectory planner. Figure 41. Summary of Experimental Data Intercept Time...DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) Quadrotor drones pose a safety hazard when operated in or near controlled airspace. A hazardous...quadrotor could be intercepted and removed by another quadrotor. In this thesis, we seek to determine if optimal control methods outperform missile

Is complex allometry in field metabolic rates of mammals a statistical artifact?

PubMed

Packard, Gary C

2017-01-01

Recent reports indicate that field metabolic rates (FMRs) of mammals conform to a pattern of complex allometry in which the exponent in a simple, two-parameter power equation increases steadily as a dependent function of body mass. The reports were based, however, on indirect analyses performed on logarithmic transformations of the original data. I re-examined values for FMR and body mass for 114 species of mammal by the conventional approach to allometric analysis (to illustrate why the approach is unreliable) and by linear and nonlinear regression on untransformed variables (to illustrate the power and versatility of newer analytical methods). The best of the regression models fitted directly to untransformed observations is a three-parameter power equation with multiplicative, lognormal, heteroscedastic error and an allometric exponent of 0.82. The mean function is a good fit to data in graphical display. The significant intercept in the model may simply have gone undetected in prior analyses because conventional allometry assumes implicitly that the intercept is zero; or the intercept may be a spurious finding resulting from bias introduced by the haphazard sampling that underlies "exploratory" analyses like the one reported here. The aforementioned issues can be resolved only by gathering new data specifically intended to address the question of scaling of FMR with body mass in mammals. However, there is no support for the concept of complex allometry in the relationship between FMR and body size in mammals. Copyright © 2016 Elsevier Inc. All rights reserved.

Random phenotypic variation of yeast (Saccharomyces cerevisiae) single-gene knockouts fits a double pareto-lognormal distribution.

PubMed

Graham, John H; Robb, Daniel T; Poe, Amy R

2012-01-01

Distributed robustness is thought to influence the buffering of random phenotypic variation through the scale-free topology of gene regulatory, metabolic, and protein-protein interaction networks. If this hypothesis is true, then the phenotypic response to the perturbation of particular nodes in such a network should be proportional to the number of links those nodes make with neighboring nodes. This suggests a probability distribution approximating an inverse power-law of random phenotypic variation. Zero phenotypic variation, however, is impossible, because random molecular and cellular processes are essential to normal development. Consequently, a more realistic distribution should have a y-intercept close to zero in the lower tail, a mode greater than zero, and a long (fat) upper tail. The double Pareto-lognormal (DPLN) distribution is an ideal candidate distribution. It consists of a mixture of a lognormal body and upper and lower power-law tails. If our assumptions are true, the DPLN distribution should provide a better fit to random phenotypic variation in a large series of single-gene knockout lines than other skewed or symmetrical distributions. We fit a large published data set of single-gene knockout lines in Saccharomyces cerevisiae to seven different probability distributions: DPLN, right Pareto-lognormal (RPLN), left Pareto-lognormal (LPLN), normal, lognormal, exponential, and Pareto. The best model was judged by the Akaike Information Criterion (AIC). Phenotypic variation among gene knockouts in S. cerevisiae fits a double Pareto-lognormal (DPLN) distribution better than any of the alternative distributions, including the right Pareto-lognormal and lognormal distributions. A DPLN distribution is consistent with the hypothesis that developmental stability is mediated, in part, by distributed robustness, the resilience of gene regulatory, metabolic, and protein-protein interaction networks. Alternatively, multiplicative cell growth, and the mixing of lognormal distributions having different variances, may generate a DPLN distribution.

Estimating energy expenditure from heart rate in older adults: a case for calibration.

PubMed

Schrack, Jennifer A; Zipunnikov, Vadim; Goldsmith, Jeff; Bandeen-Roche, Karen; Crainiceanu, Ciprian M; Ferrucci, Luigi

2014-01-01

Accurate measurement of free-living energy expenditure is vital to understanding changes in energy metabolism with aging. The efficacy of heart rate as a surrogate for energy expenditure is rooted in the assumption of a linear function between heart rate and energy expenditure, but its validity and reliability in older adults remains unclear. To assess the validity and reliability of the linear function between heart rate and energy expenditure in older adults using different levels of calibration. Heart rate and energy expenditure were assessed across five levels of exertion in 290 adults participating in the Baltimore Longitudinal Study of Aging. Correlation and random effects regression analyses assessed the linearity of the relationship between heart rate and energy expenditure and cross-validation models assessed predictive performance. Heart rate and energy expenditure were highly correlated (r=0.98) and linear regardless of age or sex. Intra-person variability was low but inter-person variability was high, with substantial heterogeneity of the random intercept (s.d. =0.372) despite similar slopes. Cross-validation models indicated individual calibration data substantially improves accuracy predictions of energy expenditure from heart rate, reducing the potential for considerable measurement bias. Although using five calibration measures provided the greatest reduction in the standard deviation of prediction errors (1.08 kcals/min), substantial improvement was also noted with two (0.75 kcals/min). These findings indicate standard regression equations may be used to make population-level inferences when estimating energy expenditure from heart rate in older adults but caution should be exercised when making inferences at the individual level without proper calibration.

Sleep to the beat: A nap favours consolidation of timing.

PubMed

Verweij, Ilse M; Onuki, Yoshiyuki; Van Someren, Eus J W; Van der Werf, Ysbrand D

2016-06-01

Growing evidence suggests that sleep is important for procedural learning, but few studies have investigated the effect of sleep on the temporal aspects of motor skill learning. We assessed the effect of a 90-min day-time nap on learning a motor timing task, using 2 adaptations of a serial interception sequence learning (SISL) task. Forty-two right-handed participants performed the task before and after a 90-min period of sleep or wake. Electroencephalography (EEG) was recorded throughout. The motor task consisted of a sequential spatial pattern and was performed according to 2 different timing conditions, that is, either following a sequential or a random temporal pattern. The increase in accuracy was compared between groups using a mixed linear regression model. Within the sleep group, performance improvement was modeled based on sleep characteristics, including spindle- and slow-wave density. The sleep group, but not the wake group, showed improvement in the random temporal, but especially and significantly more strongly in the sequential temporal condition. None of the sleep characteristics predicted improvement on either general of the timing conditions. In conclusion, a daytime nap improves performance on a timing task. We show that performance on the task with a sequential timing sequence benefits more from sleep than motor timing. More important, the temporal sequence did not benefit initial learning, because differences arose only after an offline period and specifically when this period contained sleep. Sleep appears to aid in the extraction of regularities for optimal subsequent performance. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Application of a bioenergetics model for hatchery production: Largemouth bass fed commercial diets

USGS Publications Warehouse

Csargo, Isak J.; Michael L. Brown,; Chipps, Steven R.

2012-01-01

Fish bioenergetics models based on natural prey items have been widely used to address research and management questions. However, few attempts have been made to evaluate and apply bioenergetics models to hatchery-reared fish receiving commercial feeds that contain substantially higher energy densities than natural prey. In this study, we evaluated a bioenergetics model for age-0 largemouth bass Micropterus salmoidesreared on four commercial feeds. Largemouth bass (n ≈ 3,504) were reared for 70 d at 25°C in sixteen 833-L circular tanks connected in parallel to a recirculation system. Model performance was evaluated using error components (mean, slope, and random) derived from decomposition of the mean square error obtained from regression of observed on predicted values. Mean predicted consumption was only 8.9% lower than mean observed consumption and was similar to error rates observed for largemouth bass consuming natural prey. Model evaluation showed that the 97.5% joint confidence region included the intercept of 0 (−0.43 ± 3.65) and slope of 1 (1.08 ± 0.20), which indicates the model accurately predicted consumption. Moreover model error was similar among feeds (P = 0.98), and most error was probably attributable to sampling error (unconsumed feed), underestimated predator energy densities, or consumption-dependent error, which is common in bioenergetics models. This bioenergetics model could provide a valuable tool in hatchery production of largemouth bass. Furthermore, we believe that bioenergetics modeling could be useful in aquaculture production, particularly for species lacking historical hatchery constants or conventional growth models.

Two-component duality and flavoring in the P+f model

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

Dash, J.W.; Jones, S.T.; Martin, A.

We show that modern Regge fits to rising ..pi..N total cross sections sigma/sub piN/ using the Harari-Freund P+f model of diffraction are not consistent with two-component duality. If a conventional Pomeron is chosen (dominant j-plane pole plus weak cuts), the resulting f is ''dual'' to the resonances plus one-half the background. Conversely, constraining the f-pole amplitude by duality does not allow a reasonable fit to sigma/sub piN/. In contrast, the P-f identity model of diffraction is shown to satisfy a modified form of two-component duality. We show that by incorporating flavoring renormalization, the P+f picture can be made consistent withmore » duality. The unflavored P intercept is 0.91 and the flavored P intercept is 1.1. Significant absorptive j-plane cuts are also required, though these are small enough to be consistent with dominant short-range order. Thus flavoring, which is so essential in P-f identity phenomenology, seems to play a positive role in diffraction scattering generally.« less

Importance of ecohydrological modelling approaches in the prediction of plant behaviour and water balance at different scales

NASA Astrophysics Data System (ADS)

García-Arias, Alicia; Ruiz-Pérez, Guiomar; Francés, Félix

2017-04-01

Vegetation plays a main role in the water balance of most hydrological systems. However, in the past it has been barely considered the effect of the interception and evapotranspiration for hydrological modelling purposes. During the last years many authors have recognised and supported ecohydrological approaches instead of traditional strategies. This contribution is aimed to demonstrate the pivotal role of the vegetation in ecohydrological models and that a better understanding of the hydrological systems can be achieved by considering the appropriate processes related to plants. The study is performed in two scales: the plot scale and the reach scale. At plot scale, only zonal vegetation was considered while at reach scale both zonal and riparian were taken into account. In order to assure the main role of the water on the vegetation development, semiarid environments have been selected for the case studies. Results show an increase of the capabilities to predict plant behaviour and water balance when interception and evapotranspiration are taken into account in the soil water balance

Effect of poverty reduction program on nutritional status of the extreme poor in Bangladesh.

PubMed

Jalal, Chowdhury S B; Frongillo, Edward A

2013-12-01

Poverty alleviation programs for the extreme poor improve participants' economic status and may impact other important outcomes that are seldom evaluated. A program targeted to the extreme poor by BRAG, a development organization in Bangladesh, has been successful in significantly alleviating extreme poverty. We hypothesized that the program also improved the nutritional status of women and preschool children. A nonequivalent control, pre- and posttest quasi-experimental design that was longitudinal at the village level was used to test the hypotheses. Data were collected from a random sample of 4,131 children and 3,551 women from 3,409 households in 159 villages of 3 northern districts of Bangladesh in 2002 and 2006. Linear mixed random-intercept models accounted for clustering effects and potential confounders. The weight-for-height of children between 24 and 35 months of age from program households was significantly higher (p < .05) than that of children from control households. We found no significant differences between control and program households in three other growth and body-composition indicators in three other age categories of preschool children or in women. These results are important, as this is a large-scale program that has already been extended to more than half the country. The findings will contribute to judging the cost-benefit and cost-effectiveness of the program and in garnering support for the expansion of such programs.

Association Between Cognitive Decline in Older Adults and Utilization of Primary Care Physician Services in Pennsylvania

PubMed Central

Fowler, Nicole R.; Morrow, Lisa A.; Tu, Li-Chuan; Landsittel, Douglas P.; Snitz, Beth E.; Rodriquez, Eric G.; Saxton, Judith A.

2012-01-01

OBJECTIVE To assess the relationship between cognitive decline of older patients (≥65 years) and utilization of primary care physician (PCP) services over 24-months. DESIGN Retrospective analysis of prospectively collected data from a cluster randomized trial that took place from 2006 to 2010 and investigated the relationship between formal neuropsychological evaluation and patient outcomes in primary care. SETTING Twenty-four PCPs in 11 practices in southwestern Pennsylvania. Most practices were suburban and included more than 5 PCPs. PARTICIPANTS A sample of 423 primary care patients 65 years or older. MEASUREMENTS The association between the number of PCP visits and a decline in cognitive status, as determined by multivariable analyses that controlled for patient-level, physician-level, and practice-level factors (e.g., patient age, comorbidities, and symptoms of depression; practice location and size; PCP age and sex) and used a linear mixed model with a random intercept to adjust for clustering. RESULTS Over a two year follow-up, 199 patients (47.0%) experienced a decline in cognitive status. Patients with a cognitive decline had a mean of 0.69 more PCP visits than did patients without a cognitive decline (P<0.05). CONCLUSIONS Early signs of cognitive decline may be an indicator of greater utilization of primary care. Given the demographic trends, more PCPs are likely to be needed to meet the increasing needs of the older population. PMID:22798988

Examining the Predictive Relations between Two Aspects of Self-Regulation and Growth in Preschool Children’s Early Literacy Skills

PubMed Central

Lonigan, Christopher J.; Allan, Darcey M.; Phillips, Beth M.

2016-01-01

There is strong evidence that self-regulatory processes are linked to early academic skills both concurrently and longitudinally. The majority of extant longitudinal studies, however, have been conducted using autoregressive techniques that may not accurately model change across time. The purpose of this study was to examine the unique associations between two components of self-regulation, attention and executive functioning (EF), and growth in early literacy skills over the preschool year using latent-growth-curve analysis. The sample included 1,082 preschool children (M-age = 55.0 months, SD = 3.73). Children completed measures of vocabulary, syntax, phonological awareness, print knowledge, cognitive ability, and self-regulation, and children’s classroom teachers completed a behavior rating measure. To examine the independent relations of the self-regulatory skills and cognitive ability with children’s initial early literacy skills and growth across the preschool year, growth models in which the intercept and slope were simultaneously regressed on each of the predictor variables were examined. Because of the significant relation between intercept and slope for most outcomes, slope was regressed on intercept in the models to allow a determination of direct and indirect effects of the predictors on growth in children’s language and literacy skills across the preschool year. In general, both teacher-rated inattention and directly measured EF were uniquely associated with initial skills level; however, only teacher-rated inattention uniquely predicted growth in early literacy skills. These findings suggest that teacher-ratings of inattention may measure an aspect of self-regulation that is particularly associated with the acquisition of academic skills in early childhood. PMID:27854463

Differential contributions to the interception of occluded ballistic trajectories by the temporoparietal junction, area hMT/V5+, and the intraparietal cortex.

PubMed

Delle Monache, Sergio; Lacquaniti, Francesco; Bosco, Gianfranco

2017-09-01

The ability to catch objects when transiently occluded from view suggests their motion can be extrapolated. Intraparietal cortex (IPS) plays a major role in this process along with other brain structures, depending on the task. For example, interception of objects under Earth's gravity effects may depend on time-to-contact predictions derived from integration of visual signals processed by hMT/V5+ with a priori knowledge of gravity residing in the temporoparietal junction (TPJ). To investigate this issue further, we disrupted TPJ, hMT/V5+, and IPS activities with transcranial magnetic stimulation (TMS) while subjects intercepted computer-simulated projectile trajectories perturbed randomly with either hypo- or hypergravity effects. In experiment 1 , trajectories were occluded either 750 or 1,250 ms before landing. Three subject groups underwent triple-pulse TMS (tpTMS, 3 pulses at 10 Hz) on one target area (TPJ | hMT/V5+ | IPS) and on the vertex (control site), timed at either trajectory perturbation or occlusion. In experiment 2 , trajectories were entirely visible and participants received tpTMS on TPJ and hMT/V5+ with same timing as experiment 1 tpTMS of TPJ, hMT/V5+, and IPS affected differently the interceptive timing. TPJ stimulation affected preferentially responses to 1-g motion, hMT/V5+ all response types, and IPS stimulation induced opposite effects on 0-g and 2-g responses, being ineffective on 1-g responses. Only IPS stimulation was effective when applied after target disappearance, implying this area might elaborate memory representations of occluded target motion. Results are compatible with the idea that IPS, TPJ, and hMT/V5+ contribute to distinct aspects of visual motion extrapolation, perhaps through parallel processing. NEW & NOTEWORTHY Visual extrapolation represents a potential neural solution to afford motor interactions with the environment in the face of missing information. We investigated relative contributions by temporoparietal junction (TPJ), hMT/V5+, and intraparietal cortex (IPS), cortical areas potentially involved in these processes. Parallel organization of visual extrapolation processes emerged with respect to the target's motion causal nature: TPJ was primarily involved for visual motion congruent with gravity effects, IPS for arbitrary visual motion, whereas hMT/V5+ contributed at earlier processing stages. Copyright © 2017 the American Physiological Society.

Variations in canopy and litter interception across a forest chronosequence in the southern Appalachian Mountains

Treesearch

Steven T. Brantley; Paul V. Bolstad; Stephanie H. Laseter; A. Christopher Oishi; Kimberly A. Novick; Chelcy F. Miniat

2016-01-01

Variations in evapotranspiration (ET) have been well documented across a variety of forest types and climates in recent decades; however, most of these data have focused on mature, secondgrowth stands. Here we present data on two important fluxes of water, canopy interception (Ic) and forest floor litter interception (Iff), across a chronosequence of forest age in the...

An Optimal t-{Delta}v Guidance Law for Intercepting a Boosting Target

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

Ng, L.C.; Breitfeller, E.; Ledebuhr, A.G.

2002-06-30

Lawrence Livermore National Laboratory (LLNL) have developed a new missile guidance law for intercepting a missile during boost phase. Unlike other known missile guidance laws being used today, the new t-{Delta}v guidance law optimally trades an interceptor's onboard fuel capacity against time-to-go before impact. In particular, this guidance law allows a missile designer to program the interceptor to maximally impact a boosting missile before burnout or burn termination and thus negating its ability to achieve the maximum kinetic velocity. For an intercontinental range ballistic missile (ICBM), it can be shown that for every second of earlier intercept prior to burnout,more » the ICBM ground range is reduced by 350 km. Therefore, intercepting a mere 15 seconds earlier would result in amiss of 5,250 km from the intended target or approximately a distance across the continental US. This paper also shows how the t-{Delta}v guidance law can incorporate uncertainties in target burnout time, predicted intercept point (PIP) error, time-to-go error, and other track estimation errors. The authors believe that the t-{Delta}v guidance law is a step toward the development of a new and smart missile guidance law that would enhance the probability of achieving a boost phase intercept.« less

Suborbital Asteroid Intercept and Fragmentation for Very Short Warning Time Scenarios

NASA Technical Reports Server (NTRS)

Hupp, Ryan; Dewald, Spencer; Wie, Bong; Barbee, Brent W.

2015-01-01

Small near-Earth objects (NEOs) 50150 m in size are far more numerous (hundreds of thousands to millions yet to be discovered) than larger NEOs. Small NEOs, which are mostly asteroids rather than comets, are very faint in the night sky due to their small sizes, and are, therefore, difficult to discover far in advance of Earth impact. However, even small NEOs are capable of creating explosions with energies on the order of tens or hundreds of megatons (Mt).We are, therefore, motivated to prepare to respond effectively to short warning time, small NEO impact scenarios. In this paper we explore the lower bound on actionable warning time by investigating the performance of notional upgraded Intercontinental Ballistic Missiles (ICBMs) to carry Nuclear Explosive Device (NED) payloads to intercept and disrupt a fictitious incoming NEO at high altitudes (generally, at least 2500 km above Earth). We conduct this investigation by developing optimal NEO intercept trajectories for a range of cases and comparing their performances.Our results show that suborbital NEO intercepts using Minuteman III or SM-3 IIA launch vehicles could achieve NEO intercept a few minutes prior to when the NEOwould strike Earth. We also find that more powerful versions of the launch vehicles (e.g., total V 9.511 kms) could intercept incoming NEOs over a day prior to when the NEO would strike Earth, if launched at least several days prior to the time of NEO intercept. Finally, we discuss a number of limiting factors and practicalities that affect whether the notional systems we describe could become feasible.

A comparison of four-sample slope-intercept and single-sample 51Cr-EDTA glomerular filtration rate measurements.

PubMed

Porter, Charlotte A; Bradley, Kevin M; McGowan, Daniel R

2018-05-01

The aim of this study was to verify, with a large dataset of 1394 Cr-EDTA glomerular filtration rate (GFR) studies, the equivalence of slope-intercept and single-sample GFR. Raw data from 1394 patient studies were used to calculate four-sample slope-intercept GFR in addition to four individual single-sample GFR values (blood samples taken at 90, 150, 210 and 270 min after injection). The percentage differences between the four-sample slope-intercept and each of the single-sample GFR values were calculated, to identify the optimum single-sample time point. Having identified the optimum time point, the percentage difference between the slope-intercept and optimal single-sample GFR was calculated across a range of GFR values to investigate whether there was a GFR value below which the two methodologies cannot be considered equivalent. It was found that the lowest percentage difference between slope-intercept and single-sample GFR was for the third blood sample, taken at 210 min after injection. The median percentage difference was 2.5% and only 6.9% of patient studies had a percentage difference greater than 10%. Above a GFR value of 30 ml/min/1.73 m, the median percentage difference between the slope-intercept and optimal single-sample GFR values was below 10%, and so it was concluded that, above this value, the two techniques are sufficiently equivalent. This study supports the recommendation of performing single-sample GFR measurements for GFRs greater than 30 ml/min/1.73 m.

Validation of prediction models: examining temporal and geographic stability of baseline risk and estimated covariate effects

PubMed Central

Austin, Peter C.; van Klaveren, David; Vergouwe, Yvonne; Nieboer, Daan; Lee, Douglas S.; Steyerberg, Ewout W.

2018-01-01

Background Stability in baseline risk and estimated predictor effects both geographically and temporally is a desirable property of clinical prediction models. However, this issue has received little attention in the methodological literature. Our objective was to examine methods for assessing temporal and geographic heterogeneity in baseline risk and predictor effects in prediction models. Methods We studied 14,857 patients hospitalized with heart failure at 90 hospitals in Ontario, Canada, in two time periods. We focussed on geographic and temporal variation in baseline risk (intercept) and predictor effects (regression coefficients) of the EFFECT-HF mortality model for predicting 1-year mortality in patients hospitalized for heart failure. We used random effects logistic regression models for the 14,857 patients. Results The baseline risk of mortality displayed moderate geographic variation, with the hospital-specific probability of 1-year mortality for a reference patient lying between 0.168 and 0.290 for 95% of hospitals. Furthermore, the odds of death were 11% lower in the second period than in the first period. However, we found minimal geographic or temporal variation in predictor effects. Among 11 tests of differences in time for predictor variables, only one had a modestly significant P value (0.03). Conclusions This study illustrates how temporal and geographic heterogeneity of prediction models can be assessed in settings with a large sample of patients from a large number of centers at different time periods. PMID:29350215

Quantum-key-distribution protocol with pseudorandom bases

NASA Astrophysics Data System (ADS)

Trushechkin, A. S.; Tregubov, P. A.; Kiktenko, E. O.; Kurochkin, Y. V.; Fedorov, A. K.

2018-01-01

Quantum key distribution (QKD) offers a way for establishing information-theoretical secure communications. An important part of QKD technology is a high-quality random number generator for the quantum-state preparation and for post-processing procedures. In this work, we consider a class of prepare-and-measure QKD protocols, utilizing additional pseudorandomness in the preparation of quantum states. We study one of such protocols and analyze its security against the intercept-resend attack. We demonstrate that, for single-photon sources, the considered protocol gives better secret key rates than the BB84 and the asymmetric BB84 protocols. However, the protocol strongly requires single-photon sources.

Effect of Changes in Living Conditions on Well-Being: A Prospective Top-Down Bottom-Up Model

ERIC Educational Resources Information Center

Nakazato, Naoki; Schimmack, Ulrich; Oishi, Shigehiro

2011-01-01

Using the German Socio-Economic Panel, we examined life-satisfaction and housing satisfaction before and after moving (N = 3,658 participants from 2,162 households) with univariate and bivariate two-intercept two-slope latent growth models. The main findings were (a) a strong and persistent increase in average levels of housing satisfaction, (b)…

Evaluation of the "e-rater"® Scoring Engine for the "GRE"® Issue and Argument Prompts. Research Report. ETS RR-12-02

ERIC Educational Resources Information Center

Ramineni, Chaitanya; Trapani, Catherine S.; Williamson, David M.; Davey, Tim; Bridgeman, Brent

2012-01-01

Automated scoring models for the "e-rater"® scoring engine were built and evaluated for the "GRE"® argument and issue-writing tasks. Prompt-specific, generic, and generic with prompt-specific intercept scoring models were built and evaluation statistics such as weighted kappas, Pearson correlations, standardized difference in…

Aquatic Vegetation of the St. Louis River Estuary: Initial Analysis of Point-intercept Data Collected in 2010 for Restoration Modeling.

EPA Science Inventory

A new effort to model aquatic vegetation patterns in the St. Louis River Estuary was initiated in summer of 2010 for the purpose of informing wetland restoration planning in the St. Louis River Area of Concern (AOC) at 40th Avenue West in Duluth. Aquatic vascular plants were doc...

Analysis of the lettuce data from the variable pressure growth chamber at NASA Johnson Space Center: A three-stage nested design model

NASA Technical Reports Server (NTRS)

Lee, Tze-San

1992-01-01

A model of three-stage nested experimental design was applied to analyze the lettuce data obtained from the variable pressure growth chamber test bed at NASA-Johnson Space Center. From the results of an application of the analysis of variance and covariance on the data set, it was noted that all of the (uncontrollable) factors, Side, Zone, Height and (controllable) PAR (photosynthetically active radiation), had nonhomogeneous effects on the dry weight of the edible biomass of lettuce per pot. Incidentally, the variations accountable to the (uncontrollable) factorial heterogeneities are merely 9 percent and 17 percent of the total variation for both the first and second crop test, respectively. After adjusting for the PAR as a covariate in the no-intercept model, the accountable variations to all the four factors are 94 percent and 92 percent for the first and the second crop test, respectively. With the use of a no-intercept simple linear regression model, the accountable variations to the factor PAR are 92 percent and 90 percent for the first and the second crop test, respectively. Evidently, the (controllable) factor PAR is the dominating one.

Travel cost demand model based river recreation benefit estimates with on-site and household surveys: Comparative results and a correction procedure

NASA Astrophysics Data System (ADS)

Loomis, John

2003-04-01

Past recreation studies have noted that on-site or visitor intercept surveys are subject to over-sampling of avid users (i.e., endogenous stratification) and have offered econometric solutions to correct for this. However, past papers do not estimate the empirical magnitude of the bias in benefit estimates with a real data set, nor do they compare the corrected estimates to benefit estimates derived from a population sample. This paper empirically examines the magnitude of the recreation benefits per trip bias by comparing estimates from an on-site river visitor intercept survey to a household survey. The difference in average benefits is quite large, with the on-site visitor survey yielding 24 per day trip, while the household survey yields 9.67 per day trip. A simple econometric correction for endogenous stratification in our count data model lowers the benefit estimate to $9.60 per day trip, a mean value nearly identical and not statistically different from the household survey estimate.

Precambrian U-Pb zircon ages in eclogites and garnet pyroxenites from South Brittany (France): an old oceanic crust in the West European Hercynian belt?

NASA Astrophysics Data System (ADS)

Peucat, J. J.; Vidal, Ph.; Godard, G.; Postaire, B.

1982-08-01

U-Pb zircon ages have been determined for two eclogites from the Vendée and for two garnet pyroxenites from the Baie d'Audierne. In an episodic Pb loss model, the two discordia would give upper intercept ages around 1300-1250 Ma and lower intercepts ages of 436-384 Ma. Two interpretations are proposed: (1) The 1250-1300 Ma ages may reflect an unspecified upper mantle event or process; the Paleozoic ages correspond to the tectonic emplacement of an eclogitic mantle fragment into the continental crust. (2) The protolith may have been extracted from the upper mantle 1250-1300 Ma ago and stored in a crustal environment until it was metamorphosed under high-pressure conditions around 400 Ma ago. This latter model is favoured by available geologic and isotopic data. Consequently, we propose that a 1300 Ma old oceanic crust was tectonicly incorporated into a sialic basement during the Proterozoic. This mixture was subsequently subducted during the Paleozoic.

Soil radium, soil gas radon and indoor radon empirical relationships to assist in post-closure impact assessment related to near-surface radioactive waste disposal.

PubMed

Appleton, J D; Cave, M R; Miles, J C H; Sumerling, T J

2011-03-01

Least squares (LS), Theil's (TS) and weighted total least squares (WTLS) regression analysis methods are used to develop empirical relationships between radium in the ground, radon in soil and radon in dwellings to assist in the post-closure assessment of indoor radon related to near-surface radioactive waste disposal at the Low Level Waste Repository in England. The data sets used are (i) estimated ²²⁶Ra in the < 2 mm fraction of topsoils (eRa226) derived from equivalent uranium (eU) from airborne gamma spectrometry data, (ii) eRa226 derived from measurements of uranium in soil geochemical samples, (iii) soil gas radon and (iv) indoor radon data. For models comparing indoor radon and (i) eRa226 derived from airborne eU data and (ii) soil gas radon data, some of the geological groupings have significant slopes. For these groupings there is reasonable agreement in slope and intercept between the three regression analysis methods (LS, TS and WTLS). Relationships between radon in dwellings and radium in the ground or radon in soil differ depending on the characteristics of the underlying geological units, with more permeable units having steeper slopes and higher indoor radon concentrations for a given radium or soil gas radon concentration in the ground. The regression models comparing indoor radon with soil gas radon have intercepts close to 5 Bq m⁻³ whilst the intercepts for those comparing indoor radon with eRa226 from airborne eU vary from about 20 Bq m⁻³ for a moderately permeable geological unit to about 40 Bq m⁻³ for highly permeable limestone, implying unrealistically high contributions to indoor radon from sources other than the ground. An intercept value of 5 Bq m⁻³ is assumed as an appropriate mean value for the UK for sources of indoor radon other than radon from the ground, based on examination of UK data. Comparison with published data used to derive an average indoor radon: soil ²²⁶Ra ratio shows that whereas the published data are generally clustered with no obvious correlation, the data from this study have substantially different relationships depending largely on the permeability of the underlying geology. Models for the relatively impermeable geological units plot parallel to the average indoor radon: soil ²²⁶Ra model but with lower indoor radon: soil ²²⁶Ra ratios, whilst the models for the permeable geological units plot parallel to the average indoor radon: soil ²²⁶Ra model but with higher than average indoor radon: soil ²²⁶Ra ratios. Copyright © 2010 Natural Environment Research Council. Published by Elsevier Ltd.. All rights reserved.

Psychrometric measurement of soil water potential: Stability of calibration and test of pressure-plate samples

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

Jones, T.L.; Gee, G.W.; Heller, P.R.

1990-08-01

A commercially available thermocouple psychrometer sample changer (Decagon SC-10A) was used to measure the water potential of field soils ranging in texture from sand to silty clay loam over a range of {minus}0.5 to {minus}20.0 MPa. The standard error of prediction based on regression statistics was generally between 0.04 and 0.14 MPa at {minus}5 MPa. Replacing the measuring junction of the unit changed the calibration slightly; however, it did not significantly alter measurement accuracy. Calibration curves measured throughout a year of testing are consistent and indicate no systematic drift in calibration. Most measurement uncertainty is produced by shifts in themore » intercept in the calibration equation rather than the slope. Both the variability in intercept and the regression error seem to be random. Measurements taken with the SC-10A show that water potential in both sand and silt loam samples removed from 1.5-MPa pressure plates was often 0.5 to 1.0 MPa greater than the 1.5-MPa applied pressure. Limited data from 0.5-MPa pressure plates show close agreement between SC-10A measurements and pressure applied to these more permeable plates.« less

Coupling of Processes and Data in PennState Integrated Hydrologic Modeling (PIHM) System

NASA Astrophysics Data System (ADS)

Kumar, M.; Duffy, C.

2007-12-01

Full physical coupling, "natural" numerical coupling and parsimonious but accurate data coupling is needed to comprehensively and accurately capture the interaction between different components of a hydrologic continuum. Here we present a physically based, spatially distributed hydrologic model that incorporates all the three coupling strategies. Physical coupling of interception, snow melt, transpiration, overland flow, subsurface flow, river flow, macropore based infiltration and stormflow, flow through and over hydraulic structures likes weirs and dams, and evaporation from interception, ground and overland flow is performed. All the physically coupled components are numerically coupled through semi-discrete form of ordinary differential equations, that define each hydrologic process, using Finite-Volume based approach. The fully implicit solution methodology using CVODE solver solves for all the state variables simultaneously at each adaptive time steps thus providing robustness, stability and accuracy. The accurate data coupling is aided by use of constrained unstructured meshes, flexible data model and use of PIHMgis. The spatial adaptivity of decomposed domain and temporal adaptivity of the numerical solver facilitates capture of varied spatio-temporal scales that are inherent in hydrologic process interactions. The implementation of the model has been performed on a meso-scale Little-Juniata Watershed. Model results are validated by comparison of streamflow at multiple locations. We discuss some of the interesting hydrologic interactions between surface, subsurface and atmosphere witnessed during the year long simulation such as a) inverse relationship between evaporation from interception storage and transpiration b) relative influence of forcing (precipitation, temperature and radiation) and source (soil moisture and overland flow) on evaporation c) influence of local topography on gaining, loosing or "flow-through" behavior of river-aquifer interactions d) role of macropores on base flow during wetting and drying conditions. In addition to its use as a potential predictive and exploratory science tool, we present a test case for the application of model in water management by mapping of water table decline index for the whole watershed. Also discussed will be the efficient parallelization strategy of the model for high spatio-temporal resolution simulations.

Barriers and dispersal surfaces in minimum-time interception

NASA Technical Reports Server (NTRS)

Rajan, N.; Ardema, M. D.

1982-01-01

Minimum time interception of a target moving in a horizontal plane is analyzed as a one-player differential game. Dispersal points and points on the barrier are located for a class of pursuit evasion and interception problems. These points are determined by constructing cross sections of the isochrones and hence obtaining the barrier, dispersal, and control level surfaces. The game solution maps the controls as a function of the state within the capture region.

Opportunities for ballistic missions to Halley's comet

NASA Technical Reports Server (NTRS)

Farquhar, R. W.; Wooden, W. H., II

1977-01-01

Alternative strategies for ballistic missions to Halley's comet in 1985-86 are described. A large scientific return would be acquired from a ballistic Halley intercept in spite of the high flyby speeds that are associated with this mission mode. The possibility of retargeting the cometary spacecraft to additional comets after the Halley intercept also exists. Two cometary spacecraft of identical design would be used to carry out four separate cometary encounters over a 3 year period. One spacecraft would intercept Halley's comet before its perihelion passage in December 1985 and then go on to comet Borrelly with an encounter in January 1988. The other spacecraft would be targeted for a postperihelion Halley intercept in March 1986 before proceeding toward an encounter with comet Tempel 2 in September 1988.

Integrated detection, estimation, and guidance in pursuit of a maneuvering target

NASA Astrophysics Data System (ADS)

Dionne, Dany

The thesis focuses on efficient solutions of non-cooperative pursuit-evasion games with imperfect information on the state of the system. This problem is important in the context of interception of future maneuverable ballistic missiles. However, the theoretical developments are expected to find application to a broad class of hybrid control and estimation problems in industry. The validity of the results is nevertheless confirmed using a benchmark problem in the area of terminal guidance. A specific interception scenario between an incoming target with no information and a single interceptor missile with noisy measurements is analyzed in the form of a linear hybrid system subject to additive abrupt changes. The general research is aimed to achieve improved homing accuracy by integrating ideas from detection theory, state estimation theory and guidance. The results achieved can be summarized as follows. (i) Two novel maneuver detectors are developed to diagnose abrupt changes in a class of hybrid systems (detection and isolation of evasive maneuvers): a new implementation of the GLR detector and the novel adaptive- H0 GLR detector. (ii) Two novel state estimators for target tracking are derived using the novel maneuver detectors. The state estimators employ parameterized family of functions to described possible evasive maneuvers. (iii) A novel adaptive Bayesian multiple model predictor of the ballistic miss is developed which employs semi-Markov models and ideas from detection theory. (iv) A novel integrated estimation and guidance scheme that significantly improves the homing accuracy is also presented. The integrated scheme employs banks of estimators and guidance laws, a maneuver detector, and an on-line governor; the scheme is adaptive with respect to the uncertainty affecting the probability density function of the filtered state. (v) A novel discretization technique for the family of continuous-time, game theoretic, bang-bang guidance laws is introduced. The performance of the novel algorithms is assessed for the scenario of a pursuit-evasion engagement between a randomly maneuvering ballistic missile and an interceptor. Extensive Monte Carlo simulations are employed to evaluate the main statistical properties of the algorithms. (Abstract shortened by UMI.)

Analysis of Sting Balance Calibration Data Using Optimized Regression Models

NASA Technical Reports Server (NTRS)

Ulbrich, Norbert; Bader, Jon B.

2009-01-01

Calibration data of a wind tunnel sting balance was processed using a search algorithm that identifies an optimized regression model for the data analysis. The selected sting balance had two moment gages that were mounted forward and aft of the balance moment center. The difference and the sum of the two gage outputs were fitted in the least squares sense using the normal force and the pitching moment at the balance moment center as independent variables. The regression model search algorithm predicted that the difference of the gage outputs should be modeled using the intercept and the normal force. The sum of the two gage outputs, on the other hand, should be modeled using the intercept, the pitching moment, and the square of the pitching moment. Equations of the deflection of a cantilever beam are used to show that the search algorithm s two recommended math models can also be obtained after performing a rigorous theoretical analysis of the deflection of the sting balance under load. The analysis of the sting balance calibration data set is a rare example of a situation when regression models of balance calibration data can directly be derived from first principles of physics and engineering. In addition, it is interesting to see that the search algorithm recommended the same regression models for the data analysis using only a set of statistical quality metrics.

Biomarkers of collagen turnover are related to annual change in FEV1 in patients with chronic obstructive pulmonary disease within the ECLIPSE study.

PubMed

Leeming, Diana J; Byrjalsen, Inger; Sand, Jannie M B; Bihlet, Asger R; Lange, Peter; Thal-Singer, Ruth; Miller, Bruce E; Karsdal, Morten A; Vestbo, Jørgen

2017-12-04

Change in forced expiratory volume in one second (FEV 1 ) is important for defining severity of chronic obstructive pulmonary disease (COPD). Serological neoepitope markers of collagen turnover may predict rate of change in FEV 1 . One thousand COPD subjects from the observational, multicentre, three-year ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) study (NCT00292552, trial registration in February 2006) were included. Matrix metalloproteinase (MMP)-generated fragments of collagen type I, and type VI (C1M and C6M) were assessed in month six serum samples. A random-coefficient model with both a random intercept and a random slope was used to test the ability of the markers to predict post-dose bronchodilator FEV 1 (PD-FEV 1 ) change over two years adjusting for sex, age, BMI, smoking, bronchodilator reversibility, prior exacerbations, emphysema and chronic bronchitis status at baseline. Annual change of PD-FEV 1 was estimated from a linear model for the two-year study period. Serum C1M and C6M were independent predictors of lung function change (p = 0.007/0.005). Smoking, bronchodilator reversibility, plasma hsCRP and emphysema were also significant predictors. The effect estimate between annual change in PD-FEV 1 per one standard deviation (1SD) increase of C1M and C6M was +10.4 mL/yr. and +8.6 mL/yr. C1M, and C6M, had a significant association with baseline FEV 1 . We demonstrated that markers of tissue turnover were significantly associated with lung function change. These markers may function as prognostic biomarkers and possibly as efficacy biomarkers in clinical trials focusing on lung function change in COPD. NCT00292552 , Retrospectively registered, trial registration in February 2006.

Influence of rainfall microstructure on rainfall interception

NASA Astrophysics Data System (ADS)

Zabret, Katarina; Rakovec, Jože; Mikoš, Matjaž; Šraj, Mojca

2016-04-01

Rainfall interception is part of the hydrological cycle. Precipitation, which hits vegetation, is retained on the leaves and branches, from which it eventually evaporates into the atmosphere (interception) or reaches the ground by dripping from the canopy, falling through the gaps (throughfall) and running down the stems (stemflow). The process is influenced by various meteorological and vegetation parameters. Often neglected meteorological parameter influencing rainfall interception is also rainfall microstructure. Rain is a discrete process consisting of various numbers of individual raindrops with different sizes and velocities. This properties describe rainfall microstructure which is often neglected in hydrological analysis and replaced with rainfall intensity. Throughfall, stemflow and rainfall microstructure have been measured since the beginning of the year 2014 under two tree species (Betula pendula and Pinus nigra) on a study plot in Ljubljana, Slovenia. The preliminary analysis of the influence of rainfall microstructure on rainfall interception has been conducted using three events with different characteristics measured in May 2014. Event A is quite short with low rainfall amount and moderate rainfall intensity, whereas events B and C have similar length but low and high intensities, respectively. Event A was observed on the 1st of May 2014. It was 22 minutes long and delivered 1.2 mm of rainfall. The average rainfall intensity was equal to 3.27 mm/h. The event consisted of 1,350 rain drops with average diameter of 1.517 mm and average velocity of 5.110 m/s. Both Betula pendula and Pinus nigra intercepted similar amount of rainfall, 68 % and 69 %, respectively. Event B was observed in the night from the 7th to 8th of May 2014, it was 16 hours and 18 minutes long, and delivered 4.2 mm of rainfall with average intensity of 0.97 mm/h. There were 39,108 raindrops detected with average diameter of 0.858 mm and average velocity of 3.855 m/s. Betula pendula (23 %) has intercepted significantly less rainfall than Pinus nigra (85%). Event C was also observed in the night time between 11th and 12th of May 2014, it lasted 4 hours and 12 minutes and delivered 34.6 mm of rainfall with an average intensity equal to 8.24 mm/h. During the event 147,236 raindrops with average diameter of 1.020 mm and average velocity of 4.078 m/s were detected. Betula pendula has intercepted only 6 % of rainfall whereas Pinus nigra intercepted majority of rainfall, namely 85 %. In case of B. pendula rainfall interception is increasing with higher velocity whereas it is lower for medium diameters than for smaller or larger diameters. Rainfall interception under P. nigra is decreasing with higher velocities and behaving similar as under B. pendula for different diameters but with less obvious difference between diameter classes. We will continue with the measurements and further analysis of several rainfall events will be prepared.

Dropout Prevention: An Intervention Model for Today's High Schools.

ERIC Educational Resources Information Center

Maurer, Richard D.

1982-01-01

Describes Project Intercept in Ossining (New York), which cut the high school's dropout, absence, and failure rates by involving teachers, students, and families. The program uses four major strategies--teacher/staff inservice training, alternative academic programs, student training in social and interpersonal skills, and family intervention…

Parent's social status and children's nutrition influence on the university entrance of young adults in the last two decades in Brazil.

PubMed

Baraldi, Larissa Galastri; Conde, Wolney Lisboa

2014-01-01

The analysis of social indicators and health status of parents and children is a preferred way to estimate the potential for social mobility in different societies or different periods in the same society. To analyze the evolution of educational and nutritional status of the Brazilian families by an intergenerational approach. A representative sample of the Brazilian population, consisting of parents (35 to 65 years old) and young adults (20 to 24 years old) obtained from three national surveys NHNS (1989), HBS (2003 and 2009). We performed a descriptive analysis and, for the sons, we calculated the probability of starting college using the multilevel logistic regression with random intercept model. The advance of the nutritional status of young people was statistically higher than to their parents (p < 0.005). Social conditions experienced in childhood and family status had great influence on their later school success. These data indicate improvements in social status controlled by the nutritional status, initiated in the period of 1989-2003. Although inequality persists in the country, the family's influence declined in the period 2003-2009.

Immunocompromised Travelers: Demographic Characteristics, Travel Destinations, and Pretravel Health Care from the U.S. Global TravEpiNet Consortium

PubMed Central

Schwartz, Brian S.; Rosen, Jessica; Han, Pauline V.; Hynes, Noreen A.; Hagmann, Stefan H.; Rao, Sowmya R.; Jentes, Emily S.; Ryan, Edward T.; LaRocque, Regina C.

2015-01-01

An increasing number of immunocompromised individuals are pursuing international travel, and a better understanding of their international travel patterns and pretravel health care is needed. We evaluated the clinical features, itineraries, and pretravel health care of 486 immunocompromised international travelers seen at Global TravEpiNet sites from January 2009 to June 2012. We used bivariate analyses and logistic regressions using random intercept models to compare demographic and travel characteristics, vaccines administered, and medications prescribed for immunocompromised travelers versus 30,702 immunocompetent travelers. Immunocompromised travelers pursued itineraries that were largely similar to those of immunocompetent travelers, with nearly one-third of such travelers visiting countries with low human development indices. Biological agents, including tumor necrosis factor blockers, were commonly used immunosuppressive medications among immunocompromised travelers. A strong collaboration between travel-medicine specialists, primary care doctors, and specialist physicians is needed to prepare immunocompromised people for international travel. Incorporating routine questioning and planning regarding travel into the primary care visits of immunocompromised people may be useful. PMID:26304922

The relationship between organizational policies and practices and work limitations among hospital patient care workers.

PubMed

Sparer, Emily H; Boden, Leslie I; Sorensen, Glorian; Dennerlein, Jack T; Stoddard, Anne; Wagner, Gregory R; Nagler, Eve M; Hashimoto, Dean M; Hopcia, Karen; Sabbath, Erika L

2018-05-29

We examined relationships between organizational policies and practices (OPPs) (safety practices, ergonomic practices, and people-oriented culture) and work limitations in a sample of hospital workers. We used the 6-item Work Limitations Questionnaire (WLQ) to assess workers' perceptions of health-related work limitations. Self-reported OPPs and the WLQ were collected from workers in Boston, Massachusetts (n = 1277). We conducted random-intercept multi-level logistic regression models for each OPP using stepwise selection of covariates. As the unit-average ergonomic practice score increased by one, the odds of a worker reporting work limitations decreased by approximately 39% (P-value = 0.018), adjusted for job title, age, and body mass index. A similar relationship existed for people-oriented culture (P-value = 0.038). The association between safety practices and work limitations was similar, but not statistically significant. This study demonstrated the importance of workplace OPPs. OPPs that promote positive and supportive environments and that foster improvements in ergonomics may help reduce work limitations. © 2018 Wiley Periodicals, Inc.

How to Identify Success Among Networks That Promote Active Living.

PubMed

Litt, Jill; Varda, Danielle; Reed, Hannah; Retrum, Jessica; Tabak, Rachel; Gustat, Jeanette; O'Hara Tompkins, Nancy

2015-11-01

We evaluated organization- and network-level factors that influence organizations' perceived success. This is important for managing interorganizational networks, which can mobilize communities to address complex health issues such as physical activity, and for achieving change. In 2011, we used structured interview and network survey data from 22 states in the United States to estimate multilevel random-intercept models to understand organization- and network-level factors that explain perceived network success. A total of 53 of 59 "whole networks" met the criteria for inclusion in the analysis (89.8%). Coordinators identified 559 organizations, with 3 to 12 organizations from each network taking the online survey (response rate = 69.7%; range = 33%-100%). Occupying a leadership position (P < .01), the amount of time with the network (P < .05), and support from community leaders (P < .05) emerged as correlates of perceived success. Organizations' perceptions of success can influence decisions about continuing involvement and investment in networks designed to promote environment and policy change for active living. Understanding these factors can help leaders manage complex networks that involve diverse memberships, varied interests, and competing community-level priorities.

Immunocompromised Travelers: Demographic Characteristics, Travel Destinations, and Pretravel Health Care from the U.S. Global TravEpiNet Consortium.

PubMed

Schwartz, Brian S; Rosen, Jessica; Han, Pauline V; Hynes, Noreen A; Hagmann, Stefan H; Rao, Sowmya R; Jentes, Emily S; Ryan, Edward T; LaRocque, Regina C

2015-11-01

An increasing number of immunocompromised individuals are pursuing international travel, and a better understanding of their international travel patterns and pretravel health care is needed. We evaluated the clinical features, itineraries, and pretravel health care of 486 immunocompromised international travelers seen at Global TravEpiNet sites from January 2009 to June 2012. We used bivariate analyses and logistic regressions using random intercept models to compare demographic and travel characteristics, vaccines administered, and medications prescribed for immunocompromised travelers versus 30,702 immunocompetent travelers. Immunocompromised travelers pursued itineraries that were largely similar to those of immunocompetent travelers, with nearly one-third of such travelers visiting countries with low human development indices. Biological agents, including tumor necrosis factor blockers, were commonly used immunosuppressive medications among immunocompromised travelers. A strong collaboration between travel-medicine specialists, primary care doctors, and specialist physicians is needed to prepare immunocompromised people for international travel. Incorporating routine questioning and planning regarding travel into the primary care visits of immunocompromised people may be useful. © The American Society of Tropical Medicine and Hygiene.

Reaction time in ankle movements: a diffusion model analysis

PubMed Central

Michmizos, Konstantinos P.; Krebs, Hermano Igo

2015-01-01

Reaction time (RT) is one of the most commonly used measures of neurological function and dysfunction. Despite the extensive studies on it, no study has ever examined the RT in the ankle. Twenty-two subjects were recruited to perform simple, 2- and 4-choice RT tasks by visually guiding a cursor inside a rectangular target with their ankle. RT did not change with spatial accuracy constraints imposed by different target widths in the direction of the movement. RT increased as a linear function of potential target stimuli, as would be predicted by Hick–Hyman law. Although the slopes of the regressions were similar, the intercept in dorsal–plantar (DP) direction was significantly smaller than the intercept in inversion–eversion (IE) direction. To explain this difference, we used a hierarchical Bayesian estimation of the Ratcliff's (Psychol Rev 85:59, 1978) diffusion model parameters and divided processing time into cognitive components. The model gave a good account of RTs, their distribution and accuracy values, and hence provided a testimony that the non-decision processing time (overlap of posterior distributions between DP and IE < 0.045), the boundary separation (overlap of the posterior distributions < 0.1) and the evidence accumulation rate (overlap of the posterior distributions < 0.01) components of the RT accounted for the intercept difference between DP and IE. The model also proposed that there was no systematic change in non-decision processing time or drift rate when spatial accuracy constraints were altered. The results were in agreement with the memory drum hypothesis and could be further justified neurophysiologically by the larger innervation of the muscles controlling DP movements. This study might contribute to assessing deficits in sensorimotor control of the ankle and enlighten a possible target for correction in the framework of our on-going effort to develop robotic therapeutic interventions to the ankle of children with cerebral palsy. PMID:25030966

Suborbital Intercept and Fragmentation of an Asteroid with Very Short Warning Time Scenario

NASA Technical Reports Server (NTRS)

Hupp, Ryan; DeWald, Spencer; Wie, Bong; Barbee, Brent W.

2015-01-01

Small near-Earth objects (NEOs) is approx. 50-150 m in size are far more numerous (hundreds of thousands to millions yet to be discovered) than larger NEOs. Small NEOs, which are mostly asteroids rather than comets, are very faint in the night sky due to their small sizes, and are, therefore, difficult to discover far in advance of Earth impact. Furthermore, even small NEOs are capable of creating explosions with energies on the order of tens or hundreds of megatons (Mt). We are, therefore, motivated to prepare to respond effectively to short warning time, small NEO impact scenarios. In this paper we explore the lower bound on actionable warning time by investigating the performance of notional upgraded Intercontinental Ballistic Missiles (ICBMs) to carry Nuclear Explosive Device (NED) payloads to intercept and disrupt a hypothetical incoming NEO at high altitudes (generally at least 2500 km above Earth). We conduct this investigation by developing optimal NEO intercept trajectories for a range of cases and comparing their performances. Our results show that suborbital NEO intercepts using Minuteman III or SM-3 IIA launch vehicles could achieve NEO intercept a few minutes prior to when the NEO would strike Earth. We also find that more powerful versions of the launch vehicles (e.g., total deltaV is approx. 9.5-11 km/s) could intercept incoming NEOs several hours prior to when the NEO would strike Earth, if launched at least several days prior to the time of intercept. Finally, we discuss a number of limiting factors and practicalities that affect whether the notional systems we describe could become feasible.

Mission Design and Analysis for Suborbital Intercept and Fragmentation of an Asteroid with Very Short Warning Time

NASA Technical Reports Server (NTRS)

Hupp, Ryan; DeWald, Spencer; Wie, Bong; Barbee, Brent W.

2014-01-01

Small near-Earth objects (NEOs) approximately 50-150 m in size are far more numerous (hundreds of thousands to millions yet to be discovered) than larger NEOs. Small NEOs, which are mostly asteroids rather than comets, are very faint in the night sky due to their small sizes, and are, therefore, difficult to discover far in advance of Earth impact. Furthermore, even small NEOs are capable of creating explosions with energies on the order of tens or hundreds of megatons (Mt). We are, therefore, motivated to prepare to respond effectively to short warning time, small NEO impact scenarios. In this paper we explore the lower bound on actionable warning time by investigating the performance of notional upgraded Intercontinental Ballistic Missiles (ICBMs) to carry Nuclear Explosive Device (NED) payloads to intercept and disrupt a hypothetical incoming NEO at high altitudes (generally at least 2500 km above Earth). We conduct this investigation by developing optimal NEO intercept trajectories for a range of cases and comparing their performances. Our results show that suborbital NEO intercepts using Minuteman III or SM-3 IIA launch vehicles could achieve NEO intercept a few minutes prior to when the NEO would strike Earth. We also find that more powerful versions of the launch vehicles (e.g., total delta V of approximately 9.5-11 km/s) could intercept incoming NEOs several hours prior to when the NEO would strike Earth, if launched at least several days prior to the time of intercept. Finally, we discuss a number of limiting factors and practicalities that affect whether the notional systems we describe could become feasible.

Can Collimated Extraterrestrial Signals be Intercepted?

NASA Astrophysics Data System (ADS)

Forgan, D. H.

2014-06-01

The Optical Search for Extraterrestrial Intelligence (OSETI) attempts to detect collimated, narrow-band pulses of electromagnetic radiation. These pulses may either consist of signals intentionally directed at the Earth, or signals between two star systems with a vector that unintentionally intersects the Solar System, allowing Earth to intercept the communication. But should we expect to be able to intercept these unintentional signals? And what constraints can we place upon the frequency of intelligent civilisations if we do? We carry out Monte Carlo Realisation simulations of interstellar communications between civilisations in the Galactic Habitable Zone (GHZ) using collimated beams. We measure the frequency with which beams between two stars are intercepted by a third. The interception rate increases linearly with the fraction of communicating civilisations, and as the cube of the beam opening angle, which is somewhat stronger than theoretical expectations, which we argue is due to the geometry of the GHZ. We find that for an annular GHZ containing 10,000 civilisations, intersections are unlikely unless the beams are relatively uncollimated. These results indicate that optical SETI is more likely to find signals deliberately directed at the Earth than accidentally intercepting collimated communications. Equally, civilisations wishing to establish a network of communicating species may use weakly collimated beams to build up the network through interception, if they are willing to pay a cost penalty that is lower than that meted by fully isotropic beacons. Future SETI searches should consider the possibility that communicating civilisations will attempt to strike a balance between optimising costs and encouraging contact between civilisations, and look for weakly collimated pulses as well as narrow-beam pulses directed deliberately at the Earth.

Interoperability In Multi-Layered Active Defense:The Need For Commonality And Robustness Between Active Defense Weapon Systems

DTIC Science & Technology

2016-02-16

into areas where there is no access to maritime platforms. Sea-based interceptor platforms have the ability to intercept targets at each stage of the...argues that the most efficient concept for integrating active defense weapon systems is a multi- layered architecture with redundant intercept ...faster data transfer and will prevent data loss. The need for almost 100% interception successes is increasing as the threat becomes more

Size-exclusion chromatography of tea tannins and intercepting potentials of peptides for the inhibition of trypsin-caseinolytic activity by tea tannins.

PubMed

Kasai, Naoya; Nakatsubo, Genki

2006-07-12

Molecular-weight distribution and characterization of tea tannin were investigated by high-performance liquid chromatography and the equivalent preparative exclusion gel chromatography using Sephadex G-25. The characteristics of the fractions were studied regarding the amounts of terminal catechin, sugar, and gallic acid, the color reaction of the Folin-Chiocalteu reagent, the UV absorbance, and the inhibition activity for the trypsin-caseinolytic activity per weight. Furthermore, we investigated the intercepting activities of the inhibition by the amino acids, peptides, their analogues, poly(ethylene glycol)s (PEGs), and histatin 5 using the inhibition of trypsin-caseinolytic activity by tea. Arg, Lys, and their peptides had strong intercepting activities for the inhibition, but only a weak activity was detected in the Pro peptides or gelatin-like peptides of (Pro-Pro-Gly)(n) (n = 5 or 10). The guanidyl group of Arg and the amino methylene group of Lys were important for the intercepting activity, but the activity was weakly dependent upon the peptide bond formation. The intercepting activity of the peptides or PEG exponentially increased with the number of polymerizations. Histatin 5 did not have a remarkably strong intercepting activity considering the peptide length. The activity of the synthetic histatin 5 in which all of the Lys and Arg were substituted by Ala was at the same level as histatin 5.

47 CFR 0.251 - Authority delegated.

Code of Federal Regulations, 2010 CFR

2010-10-01

... interception of telephone conversations. Nothing in this paragraph, however, shall affect the authority of the Inspector General to intercept or record telephone conversations as necessary in the conduct of...

Some climatological factors of pine in the lake toba catchment area

NASA Astrophysics Data System (ADS)

Nasution, Z.

2018-02-01

The article deals with climatological factors of Pine at the Lake Toba Catchment Area also called drained basin, Pinus merkusii is a plant endemic in Sumatra. A central population of Pine in North Sumatra is located in the Tapanuli region to south of Lake Toba. Junghuhn discovered the species in the mountains range of Sipirok. He provisionally named the species as Pinus sumatrana. The article presents a detail analysis of approaches to climate factors, considers rainfall, air temperature, humidity, stemflow, throughfall and Interception following calculation of regression to determine relationship between precipitation with stemflow and interception. Stemflow, it is highly significant with significance of difference between correlation coefficients and z normal distribution. Temperature and relative humidity are the important components in the climate. These components influence the evaporation process and rainfall in the catchment. Pinus merkusii has the big crown interception. Stemflow and Interception has an opposite relation. Increasing of interception capacity will decrease stemflow. This type of Pine also has rough bark however significant channels so that, it flows water even during the wet season and caused the stemflow in Pinus merkusii relatively bigger.

Seedlings of temperate rainforest conifer and angiosperm trees differ in leaf area display.

PubMed

Lusk, Christopher H; Pérez-Millaqueo, Manuel M; Saldaña, Alfredo; Burns, Bruce R; Laughlin, Daniel C; Falster, Daniel S

2012-07-01

The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings' initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers. This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LAR(d)) was used to indicate plant light interception potential: LAR(d) is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle. Angiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LAR(d) was about twice that of conifers. Although specific leaf area was the most pervasive influence on LAR(d), differences in self-shading also significantly influenced LAR(d) of large seedlings. The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition.

Seedlings of temperate rainforest conifer and angiosperm trees differ in leaf area display

PubMed Central

Lusk, Christopher H.; Pérez-Millaqueo, Manuel M.; Saldaña, Alfredo; Burns, Bruce R.; Laughlin, Daniel C.; Falster, Daniel S.

2012-01-01

Background and Aims The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings' initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers. Methods This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LARd) was used to indicate plant light interception potential: LARd is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle. Results Angiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LARd was about twice that of conifers. Although specific leaf area was the most pervasive influence on LARd, differences in self-shading also significantly influenced LARd of large seedlings. Conclusions The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition. PMID:22585929

Temporal changes in randomness of bird communities across Central Europe.

PubMed

Renner, Swen C; Gossner, Martin M; Kahl, Tiemo; Kalko, Elisabeth K V; Weisser, Wolfgang W; Fischer, Markus; Allan, Eric

2014-01-01

Many studies have examined whether communities are structured by random or deterministic processes, and both are likely to play a role, but relatively few studies have attempted to quantify the degree of randomness in species composition. We quantified, for the first time, the degree of randomness in forest bird communities based on an analysis of spatial autocorrelation in three regions of Germany. The compositional dissimilarity between pairs of forest patches was regressed against the distance between them. We then calculated the y-intercept of the curve, i.e. the 'nugget', which represents the compositional dissimilarity at zero spatial distance. We therefore assume, following similar work on plant communities, that this represents the degree of randomness in species composition. We then analysed how the degree of randomness in community composition varied over time and with forest management intensity, which we expected to reduce the importance of random processes by increasing the strength of environmental drivers. We found that a high portion of the bird community composition could be explained by chance (overall mean of 0.63), implying that most of the variation in local bird community composition is driven by stochastic processes. Forest management intensity did not consistently affect the mean degree of randomness in community composition, perhaps because the bird communities were relatively insensitive to management intensity. We found a high temporal variation in the degree of randomness, which may indicate temporal variation in assembly processes and in the importance of key environmental drivers. We conclude that the degree of randomness in community composition should be considered in bird community studies, and the high values we find may indicate that bird community composition is relatively hard to predict at the regional scale.

Reading and lexical-decision tasks generate different patterns of individual variability as a function of condition difficulty.

PubMed

Zoccolotti, Pierluigi; De Luca, Maria; Di Filippo, Gloria; Marinelli, Chiara Valeria; Spinelli, Donatella

2018-06-01

We reanalyzed previous experiments based on lexical-decision and reading-aloud tasks in children with dyslexia and control children and tested the prediction of the difference engine model (DEM) that mean condition reaction times (RTs) and standard deviations (SDs) would be linearly related (Myerson et al., 2003). Then we evaluated the slope and the intercept with the x-axis of these linear functions in comparison with previously reported values (i.e., slope of about 0.30 and intercept of about 300 ms). In the case of lexical decision, the parameters were close to these values; by contrast, in the case of reading aloud, a much steeper slope (0.66) and a greater intercept (482.6 ms) were found. Therefore, interindividual variability grows at a much faster rate as a function of condition difficulty for reading than for lexical-decision tasks (or for other tasks reported in the literature). According to the DEM, the slope of the regression that relates means and SDs indicates the degree of correlation among the durations of the stages of processing. We propose that the need for a close coupling between orthographic and phonological processing in reading is what drives the particularly strong relationship between performance and interindividual variability that we observed in reading tasks.

Children’s Negative Emotions and Ego-Resiliency: Longitudinal Relations With Social Competence

PubMed Central

Taylor, Zoe E.; Eisenberg, Nancy; VanSchyndel, Sarah K.; Eggum-Wilkens, Natalie D.; Spinrad, Tracy L.

2015-01-01

We examined the relations of negative emotions in toddlerhood to the development of ego-resiliency and social competence across early childhood. Specifically, we addressed whether fear and anger/frustration in 30-month-old children (N = 213) was associated with the development of ego-resiliency across 4 time points (42 to 84 months), and, in turn, whether ego-resiliency predicted social competence at 84 months. Child anger/frustration negatively predicted the intercept of ego-resiliency at 42 months (controlling for prior ego-resiliency at 18 months) as well as the slope. Fear did not significantly predict either the intercept or slope of ego-resiliency in the structural model, although it was positively correlated with anger/frustration and was negatively related to ego-resiliency in zero-order correlations. The slope of ego-resiliency was positively related to children’s social competence at 84 months; however, the intercept of ego-resiliency (set at 42 months) was not a significant predictor of later social competence. Furthermore, the slope of ego-resiliency mediated the relations between anger/frustration and children’s later social competence. The results suggest that individual differences in anger/frustration might contribute to the development of ego-resiliency, which, in turn, is associated with children’s social competence. PMID:24364850

Evaluation of two least toxic integrated pest management programs for managing bed bugs (Heteroptera: Cimicidae) with discussion of a bed bug intercepting device.

PubMed

Wang, Changlu; Gibb, Timothy; Bennett, Gary W

2009-05-01

The cost and effectiveness of two bed bug (Cimex lectularius L.) integrated pest management (IPM) programs were evaluated for 10 wk. Sixteen bed bug-infested apartments were chosen from a high-rise low-income apartment building. The apartments were randomly divided into two treatment groups: diatomaceous earth dust-based IPM (D-IPM) and chlorfenapyr spray-based IPM (S-IPM). The initial median (minimum, maximum) bed bug counts (by visual inspection) of the two treatment groups were 73.5 (10, 352) and 77 (18, 3025), respectively. A seminar and an educational brochure were delivered to residents and staff. It was followed by installing encasements on mattresses and box springs and applying hot steam to bed bug-infested areas in all 16 apartments. Diatomaceous earth dust (Mother Earth-D) was applied in the D-IPM group 2 d after steaming. In addition, bed bug-intercepting devices were installed under legs of infested beds or sofas or chairs to intercept bed bugs. The S-IPM group only received 0.5% chlorfenapyr spray (Phantom) after the nonchemical treatments. All apartments were monitored bi-weekly and retreated when necessary. After 10 wk, bed bugs were eradicated from 50% of the apartments in each group. Bed bug count reduction (mean +/- SEM) was 97.6 +/- 1.6 and 89.7 +/- 7.3% in the D-IPM and S-IPM groups, respectively. Mean treatment costs in the 10-wk period were $463 and $482 per apartment in the D-IPM and S-IPM groups, respectively. Bed bug interceptors trapped an average of 219 +/- 135 bed bugs per apartment in 10 wk. The interceptors contributed to the IPM program efficacy and were much more effective than visual inspections in estimating bed bug numbers and determining the existence of bed bug infestations.

Standardization of automated 25-hydroxyvitamin D assays: How successful is it?

PubMed

Elsenberg, E H A M; Ten Boekel, E; Huijgen, H; Heijboer, A C

2017-12-01

Multiple 25(OH)D assays have recently been aligned to improve comparibility. In this study we investigated the performance of these assays using both native single-donor sera with target values certified by a reference method as well as single donor sera from a heterogeneous patient population. 25(OH)D levels were measured in twenty reference samples (Ref!25OHD; Labquality, Finland) using five automated methods (Lumipulse, Liaison, Cobas, iSYS and Access) and one aligned ID-XLC-MS/MS method (slope: 1,00; intercept: 0,00; R=0,996). Furthermore, 25(OH)D concentrations measured in 50 pregnant women and 52 random patients using the 5 automated assays were compared to the ID-XLC-MS/MS. In addition, Vitamin D binding protein (DBP) was measured. Most automated assays showed significant differences in 25(OH)D levels measured in reference samples. Slopes varied from 1,00 to 1,33, intercepts from -5.48 to -15,81nmol/L and the R from 0,971 to 0,997. This inaccuracy was even more prominent in a heterogeneous patient population. Slopes varied from 0,75 to 1,35, intercepts from -9.02 to 11,51nmol/L and the R from 0,840 to 0,949. For most assays the deviation in 25(OH)D concentration increased with elevating DBP concentrations suggesting that DBP might be one of the factors contributing to the inaccuracy in currently used automated 25(OH)D methods. Despite the use of standardized assays, we observed significant differences in 25(OH)D concentrations in some automated methods using reference material obtained from healthy single donor sera. In sera of a patient population this inaccuracy was even worse which is highly concerning as patient samples are being investigated in clinical laboratories. Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

The expression of light-related leaf functional traits depends on the location of individual leaves within the crown of isolated Olea europaea trees

PubMed Central

Escribano-Rocafort, Adrián G.; Ventre-Lespiaucq, Agustina B.; Granado-Yela, Carlos; Rubio de Casas, Rafael; Delgado, Juan A.; Balaguer, Luis

2016-01-01

Background The spatial arrangement and expression of foliar syndromes within tree crowns can reflect the coupling between crown form and function in a given environment. Isolated trees subjected to high irradiance and concomitant stress may adjust leaf phenotypes to cope with environmental gradients that are heterogeneous in space and time within the tree crown. The distinct expression of leaf phenotypes among crown positions could lead to complementary patterns in light interception at the crown scale. Methods We quantified eight light-related leaf traits across 12 crown positions of ten isolated Olea europaea trees in the field. Specifically, we investigated whether the phenotypic expression of foliar traits differed among crown sectors and layers and five periods of the day from sunrise to sunset. We investigated the consequences in terms of the exposed area of the leaves at the tree scale during a single day. Key Results All traits differed among crown positions except the length-to-width ratio of the leaves. We found a strong complementarity in the patterns of the potential exposed area of the leaves among day periods as a result of a non-random distribution of leaf angles across the crown. Leaf exposure at the outer layer was below 60 % of the displayed surface, reaching maximum interception during morning periods. Daily interception increased towards the inner layer, achieving consecutive maximization from east to west positions within the crown, matching the sun’s trajectory. Conclusions The expression of leaf traits within isolated trees of O. europaea varies continuously through the crown in a gradient of leaf morphotypes and leaf angles depending on the exposure and location of individual leaves. The distribution of light-related traits within the crown and the complementarity in the potential exposure patterns of the leaves during the day challenges the assumption of low trait variability within individuals. PMID:26944783

Networking in the Presence of Adversaries

DTIC Science & Technology

2014-09-12

a topological graph with linear algebraic constraints. As a practical example, such a model arises from an electric power system in which the power...flow is governed by the Kirchhoff law. When an adversary launches an MiM data attack, part of the sensor data are intercepted and substituted with

Apportionment of rainfall in central Himalayan forests (India)

NASA Astrophysics Data System (ADS)

Pathak, P. C.; Pandey, A. N.; Singh, J. S.

1985-02-01

The apportionment of rainfall into throughfall, stemflow and interception in certain forests of Kumaun Himalaya was assessed during the 1981 and 1982 monsoon seasons. Stemflow accounted for 0.28-0.89%, throughfall 74.7-91.5% and interception 8.1-25.0% of gross rainfall. The absolute values of throughfall, stemflow and interception were influenced by tree species. Overland flow was low for all forests, indicating that the latter are subsurface flow systems and, consequently, are specially susceptible to deforestation.

Fog interception by Ball moss (Tillandsia recurvata)

NASA Astrophysics Data System (ADS)

Guevara-Escobar, A.; Cervantes-Jiménez, M.; Suzán-Azpiri, H.; González-Sosa, E.; Hernández-Sandoval, L.; Malda-Barrera, G.; Martínez-Díaz, M.

2010-03-01

Interception losses are a major influence in the water yield of vegetated areas. For most storms, interception results in less water reaching the ground. However, fog drip or occult precipitation can result in negative interception because small drops are deposited on all plant surfaces and subsequently fall to the ground once vegetation storage capacities are exceeded. Fog drip is normally disregarded, but for some plant communities, it could be a mechanism offsetting evaporation losses. Tillandsia recurvata is a cosmopolitan epiphyte adapted to arid habitats where fog may be an important water source. Therefore, the interception storage capacity by T. recurvata was measured in controlled conditions through applying simulated rain or fog. The storage capacity was proportional to dry weight mass. Nocturnal stomatic opening in T. recurvata is not only relevant for CO2 but for water vapor, as suggested by the higher weight change of specimens wetted with fog for 1 h at dark in comparison to those wetted during daylight (543±77 vs. 325±56 mg, p=0.048). The coefficients obtained in the laboratory were used together with biomass measurements for T. recurvata in a xeric scrub to calculate the depth of water intercepted. Interception storage capacity (Cmin) was 0.19 and 0.54 mm for rainfall and fog respectively. T. recurvata contributed 20% to the rain interception of their shrub hosts: Acacia farnesiana and Prosopis laevigata. Meteorological data registered during one year at Cadereyta, México showed that radiative fog formation was possible during the dry season. The results showed the potential role of T. recurvata in capturing fog, which probably is a main source of water during the dry season that supports their reproductive and physiological activity at that time. The storage capacity of T. recurvata leaf surfaces could increase the amount of water available for evaporation, but as this species colonise montane forests, the effect could be negative on water recharge, because in the laboratory experiments it took up to 12 h to reach saturation conditions when fog was applied.

The Relationship Between Oxygen Reserve Index and Arterial Partial Pressure of Oxygen During Surgery

PubMed Central

Dorotta, Ihab L.; Wells, Briana; Juma, David; Applegate, Patricia M.

2016-01-01

BACKGROUND: The use of intraoperative pulse oximetry (Spo2) enhances hypoxia detection and is associated with fewer perioperative hypoxic events. However, Spo2 may be reported as 98% when arterial partial pressure of oxygen (Pao2) is as low as 70 mm Hg. Therefore, Spo2 may not provide advance warning of falling arterial oxygenation until Pao2 approaches this level. Multiwave pulse co-oximetry can provide a calculated oxygen reserve index (ORI) that may add to information from pulse oximetry when Spo2 is >98%. This study evaluates the ORI to Pao2 relationship during surgery. METHODS: We studied patients undergoing scheduled surgery in which arterial catheterization and intraoperative arterial blood gas analysis were planned. Data from multiple pulse co-oximetry sensors on each patient were continuously collected and stored on a research computer. Regression analysis was used to compare ORI with Pao2 obtained from each arterial blood gas measurement and changes in ORI with changes in Pao2 from sequential measurements. Linear mixed-effects regression models for repeated measures were then used to account for within-subject correlation across the repeatedly measured Pao2 and ORI and for the unequal time intervals of Pao2 determination over elapsed surgical time. Regression plots were inspected for ORI values corresponding to Pao2 of 100 and 150 mm Hg. ORI and Pao2 were compared using mixed-effects models with a subject-specific random intercept. RESULTS: ORI values and Pao2 measurements were obtained from intraoperative data collected from 106 patients. Regression analysis showed that the ORI to Pao2 relationship was stronger for Pao2 to 240 mm Hg (r2 = 0.536) than for Pao2 over 240 mm Hg (r2 = 0.0016). Measured Pao2 was ≥100 mm Hg for all ORI over 0.24. Measured Pao2 was ≥150 mm Hg in 96.6% of samples when ORI was over 0.55. A random intercept variance component linear mixed-effects model for repeated measures indicated that Pao2 was significantly related to ORI (β[95% confidence interval] = 0.002 [0.0019–0.0022]; P < 0.0001). A similar analysis indicated a significant relationship between change in Pao2 and change in ORI (β [95% confidence interval] = 0.0044 [0.0040–0.0048]; P < 0.0001). CONCLUSIONS: These findings suggest that ORI >0.24 can distinguish Pao2 ≥100 mm Hg when Spo2 is over 98%. Similarly, ORI > 0.55 appears to be a threshold to distinguish Pao2 ≥150 mm Hg. The usefulness of these values should be evaluated prospectively. Decreases in ORI to near 0.24 may provide advance indication of falling Pao2 approaching 100 mm Hg when Spo2 is >98%. The clinical utility of interventions based on continuous ORI monitoring should be studied prospectively. PMID:27007078

The Relationship Between Oxygen Reserve Index and Arterial Partial Pressure of Oxygen During Surgery.

PubMed

Applegate, Richard L; Dorotta, Ihab L; Wells, Briana; Juma, David; Applegate, Patricia M

2016-09-01

The use of intraoperative pulse oximetry (SpO2) enhances hypoxia detection and is associated with fewer perioperative hypoxic events. However, SpO2 may be reported as 98% when arterial partial pressure of oxygen (PaO2) is as low as 70 mm Hg. Therefore, SpO2 may not provide advance warning of falling arterial oxygenation until PaO2 approaches this level. Multiwave pulse co-oximetry can provide a calculated oxygen reserve index (ORI) that may add to information from pulse oximetry when SpO2 is >98%. This study evaluates the ORI to PaO2 relationship during surgery. We studied patients undergoing scheduled surgery in which arterial catheterization and intraoperative arterial blood gas analysis were planned. Data from multiple pulse co-oximetry sensors on each patient were continuously collected and stored on a research computer. Regression analysis was used to compare ORI with PaO2 obtained from each arterial blood gas measurement and changes in ORI with changes in PaO2 from sequential measurements. Linear mixed-effects regression models for repeated measures were then used to account for within-subject correlation across the repeatedly measured PaO2 and ORI and for the unequal time intervals of PaO2 determination over elapsed surgical time. Regression plots were inspected for ORI values corresponding to PaO2 of 100 and 150 mm Hg. ORI and PaO2 were compared using mixed-effects models with a subject-specific random intercept. ORI values and PaO2 measurements were obtained from intraoperative data collected from 106 patients. Regression analysis showed that the ORI to PaO2 relationship was stronger for PaO2 to 240 mm Hg (r = 0.536) than for PaO2 over 240 mm Hg (r = 0.0016). Measured PaO2 was ≥100 mm Hg for all ORI over 0.24. Measured PaO2 was ≥150 mm Hg in 96.6% of samples when ORI was over 0.55. A random intercept variance component linear mixed-effects model for repeated measures indicated that PaO2 was significantly related to ORI (β[95% confidence interval] = 0.002 [0.0019-0.0022]; P < 0.0001). A similar analysis indicated a significant relationship between change in PaO2 and change in ORI (β [95% confidence interval] = 0.0044 [0.0040-0.0048]; P < 0.0001). These findings suggest that ORI >0.24 can distinguish PaO2 ≥100 mm Hg when SpO2 is over 98%. Similarly, ORI > 0.55 appears to be a threshold to distinguish PaO2 ≥150 mm Hg. The usefulness of these values should be evaluated prospectively. Decreases in ORI to near 0.24 may provide advance indication of falling PaO2 approaching 100 mm Hg when SpO2 is >98%. The clinical utility of interventions based on continuous ORI monitoring should be studied prospectively.

Improving Elementary School Quality Through the Use of a Social-Emotional and Character Development Program: A Matched-Pair, Cluster-Randomized, Controlled Trial in Hawai’i

PubMed Central

Snyder, Frank J.; Vuchinich, Samuel; Acock, Alan; Washburn, Isaac J.; Flay, Brian R.

2012-01-01

BACKGROUND School safety and quality affect student learning and success. This study examined the effects of a comprehensive elementary school-wide social-emotional and character education program, Positive Action, on teacher, parent, and student perceptions of school safety and quality utilizing a matched-pair, cluster-randomized, controlled design. The Positive Action Hawai’i trial included 20 racially/ethnically diverse schools and was conducted from 2002–2003 through 2005–2006. METHODS School-level archival data, collected by the Hawai’i Department of Education, were used to examine program effects at 1-year post-trial. Teacher, parent, and student data were analyzed to examine indicators of school quality such as student safety and well-being, involvement, and satisfaction, as well as overall school quality. Matched-paired t-tests were used for the primary analysis, and sensitivity analyses included permutation tests and random-intercept growth curve models. RESULTS Analyses comparing change from baseline to 1-year post-trial revealed that intervention schools demonstrated significantly improved school quality compared to control schools, with 21%, 13%, and 16% better overall school quality scores as reported by teachers, parents, and students, respectively. Teacher, parent, and student reports on individual school-quality indicators showed improvement in student safety and well-being, involvement, satisfaction, quality student support, focused and sustained action, standards-based learning, professionalism and system capacity, and coordinated team work. Teacher reports also showed an improvement in the responsiveness of the system. CONCLUSIONS School quality was substantially improved, providing evidence that a school-wide social-emotional and character education program can enhance school quality and facilitate whole-school change. PMID:22142170

Improving elementary school quality through the use of a social-emotional and character development program: a matched-pair, cluster-randomized, controlled trial in Hawai'i.

PubMed

Snyder, Frank J; Vuchinich, Samuel; Acock, Alan; Washburn, Isaac J; Flay, Brian R

2012-01-01

School safety and quality affect student learning and success. This study examined the effects of a comprehensive elementary school-wide social-emotional and character education program, Positive Action, on teacher, parent, and student perceptions of school safety and quality utilizing a matched-pair, cluster-randomized, controlled design. The Positive Action Hawai'i trial included 20 racially/ethnically diverse schools and was conducted from 2002-2003 through 2005-2006. School-level archival data, collected by the Hawai'i Department of Education, were used to examine program effects at 1-year post-trial. Teacher, parent, and student data were analyzed to examine indicators of school quality such as student safety and well-being, involvement, and satisfaction, as well as overall school quality. Matched-paired t-tests were used for the primary analysis, and sensitivity analyses included permutation tests and random-intercept growth curve models. Analyses comparing change from baseline to 1-year post-trial revealed that intervention schools demonstrated significantly improved school quality compared to control schools, with 21%, 13%, and 16% better overall school quality scores as reported by teachers, parents, and students, respectively. Teacher, parent, and student reports on individual school-quality indicators showed improvement in student safety and well-being, involvement, satisfaction, quality student support, focused and sustained action, standards-based learning, professionalism and system capacity, and coordinated team work. Teacher reports also showed an improvement in the responsiveness of the system. School quality was substantially improved, providing evidence that a school-wide social-emotional and character education program can enhance school quality and facilitate whole-school change. © 2011, American School Health Association.

"Push as hard as you can" instruction for telephone cardiopulmonary resuscitation: a randomized simulation study.

PubMed

van Tulder, Raphael; Roth, Dominik; Havel, Christof; Eisenburger, Philip; Heidinger, Benedikt; Chwojka, Christof Constantin; Novosad, Heinz; Sterz, Fritz; Herkner, Harald; Schreiber, Wolfgang

2014-03-01

The medical priority dispatch system (MPDS®) assists lay rescuers in protocol-driven telephone-assisted cardiopulmonary resuscitation (CPR). Our aim was to clarify which CPR instruction leads to sufficient compression depth. This was an investigator-blinded, randomized, parallel group, simulation study to investigate 10 min of chest compressions after the instruction "push down firmly 5 cm" vs. "push as hard as you can." Primary outcome was defined as compression depth. Secondary outcomes were participants exertion measured by Borg scale, provider's systolic and diastolic blood pressure, and quality values measured by the skill-reporting program of the Resusci(®) Anne Simulator manikin. For the analysis of the primary outcome, we used a linear random intercept model to allow for the repeated measurements with the intervention as a covariate. Thirteen participants were allocated to control and intervention. One participant (intervention) dropped out after min 7 because of exhaustion. Primary outcome showed a mean compression depth of 44.1 mm, with an inter-individual standard deviation (SDb) of 13.0 mm and an intra-individual standard deviation (SDw) of 6.7 mm for the control group vs. 46.1 mm and a SDb of 9.0 mm and SDw of 10.3 mm for the intervention group (difference: 1.9; 95% confidence interval -6.9 to 10.8; p = 0.66). Secondary outcomes showed no difference for exhaustion and CPR-quality values. There is no difference in compression depth, quality of CPR, or physical strain on lay rescuers using the initial instruction "push as hard as you can" vs. the standard MPDS(®) instruction "push down firmly 5 cm." Copyright © 2014 Elsevier Inc. All rights reserved.

Response to depression treatment in the Aging Brain Care Medical Home model.

PubMed

LaMantia, Michael A; Perkins, Anthony J; Gao, Sujuan; Austrom, Mary G; Alder, Cathy A; French, Dustin D; Litzelman, Debra K; Cottingham, Ann H; Boustani, Malaz A

2016-01-01

To evaluate the effect of the Aging Brain Care (ABC) Medical Home program's depression module on patients' depression severity measurement over time. Retrospective chart review. Public hospital system. Patients enrolled in the ABC Medical Home program between October 1, 2012 and March 31, 2014. The response of 773 enrolled patients who had multiple patient health questionnaire-9 (PHQ-9) scores recorded in the ABC Medical Home program's depression care protocol was evaluated. Repeatedly measured PHQ-9 change scores were the dependent variables in the mixed effects models, and demographic and comorbid medical conditions were tested as potential independent variables while including random effects for time and intercept. Among those patients with baseline PHQ-9 scores >10, there was a significant decrease in PHQ-9 scores over time ( P <0.001); however, the effect differed by gender ( P =0.015). On average, women's scores (4.5 point drop at 1 month) improved faster than men's scores (1 point drop at 1 month). Moreover, both men and women had a predicted drop of 7 points (>50% decline from baseline) on the PHQ-9 at 6 months. These analyses demonstrate evidence for the sustained effectiveness of the ABC Medical Home program at inducing depression remission outcomes while employing clinical staff who required less formal training than earlier clinical trials.

Middle school-aged child enjoyment of food tastings predicts interest in nutrition education on osteoporosis prevention

PubMed Central

Cheng, Feon W.; Monnat, Shannon M.; Lohse, Barbara

2015-01-01

BACKGROUND NEEDs for Bones (NFB), based on the Health Belief Model, is a 4-lesson osteoporosis-prevention curriculum for 11-14 year-olds. This study examined the relationship between enjoyment of food tastings and interest in NFB. METHODS NFB was administered by teachers as part of standard practice and evaluated after the 4th lesson using a 21-item survey. Significant clustering of students within classrooms required use of random-intercept multilevel ordinal regression models in SAS proc GLIMMIX, with students nested within classrooms. Analyses considered tasting experience, eating attitudes, sex, grade, and cohort. RESULTS Students (N = 1619; 50% girls) participated from 85 4th-8th grade classrooms (47% 6th grade; 31% 7th grade) in 16 Pennsylvania SNAP-Ed eligible schools over 2 academic years. For all foods tasted, students who did not enjoy the food tasting were less interested in the lesson than students who did enjoy the food tasting (all p < .001); refried beans (OR 0.30), soy milk (OR = 0.55), cranapple juice (OR = 0.51), sunflower kernels (OR = 0.48), and Swiss cheese (OR = 0.49). CONCLUSIONS Enjoyment of food tasting activities can predict interest in nutrition education on osteoporosis prevention, supporting resource allocation and inclusion of food tasting activities in school-age nutrition education. PMID:26032277

Investigating the Associations between Ethnic Networks, Community Social Capital, and Physical Health among Marriage Migrants in Korea.

PubMed

Kim, Harris Hyun-Soo

2018-01-17

This study examines factors associated with the physical health of Korea's growing immigrant population. Specifically, it focuses on the associations between ethnic networks, community social capital, and self-rated health (SRH) among female marriage migrants. For empirical testing, secondary analysis of a large nationally representative sample (NSMF 2009) is conducted. Given the clustered data structure (individuals nested in communities), a series of two-level random intercepts and slopes models are fitted to probe the relationships between SRH and interpersonal (bonding and bridging) networks among foreign-born wives in Korea. In addition to direct effects, cross-level interaction effects are investigated using hierarchical linear modeling. While adjusting for confounders, bridging (inter-ethnic) networks are significantly linked with better health. Bonding (co-ethnic) networks, to the contrary, are negatively associated with immigrant health. Net of individual-level covariates, living in a commuijnity with more aggregate bridging social capital is positively linked with health. Community-level bonding social capital, however, is not a significant predictor. Lastly, two cross-level interaction terms are found. First, the positive relationship between bridging network and health is stronger in residential contexts with more aggregate bridging social capital. Second, it is weaker in communities with more aggregate bonding social capital.

Effect of neighborhood exposures on changes in weight among women in Cebu, Philippines (1983-2002).

PubMed

Colchero, M Arantxa; Bishai, David

2008-03-01

The authors aimed to identify the contributions of community factors to weight change in a cohort of women from Metropolitan Cebu, Philippines, between 1983 and 2002. The authors created a three-level random-intercept model to see whether mean body mass index (BMI; weight (kg)/height (m)(2)) varied by individual- and cluster-level variables and identified community characteristics associated with changes in BMI among 2,952 nonpregnant women. The average BMI among women living in places with four public amenities (telephones, electricity, mail delivery, and newspapers) was 0.16 kg/m(2) (95% confidence interval: 0.07, 0.26) higher than that of women living in places with fewer than three amenities. An increase in population density of 10,000 persons per km(2) was associated with a BMI increase of 0.09 kg/m(2) (95% confidence interval: 0.05, 0.13). A model with interactions revealed that the effect of population density increased significantly over time. These findings confirm earlier observations that in low-income countries, obesity starts among the wealthiest communities. Secondary and tertiary prevention policies designed to reduce obesity should be implemented in the most economically developed areas first. Primary prevention would be most needed in less developed areas, where the obesity epidemic is just beginning.

Statistical method to compare massive parallel sequencing pipelines.

PubMed

Elsensohn, M H; Leblay, N; Dimassi, S; Campan-Fournier, A; Labalme, A; Roucher-Boulez, F; Sanlaville, D; Lesca, G; Bardel, C; Roy, P

2017-03-01

Today, sequencing is frequently carried out by Massive Parallel Sequencing (MPS) that cuts drastically sequencing time and expenses. Nevertheless, Sanger sequencing remains the main validation method to confirm the presence of variants. The analysis of MPS data involves the development of several bioinformatic tools, academic or commercial. We present here a statistical method to compare MPS pipelines and test it in a comparison between an academic (BWA-GATK) and a commercial pipeline (TMAP-NextGENe®), with and without reference to a gold standard (here, Sanger sequencing), on a panel of 41 genes in 43 epileptic patients. This method used the number of variants to fit log-linear models for pairwise agreements between pipelines. To assess the heterogeneity of the margins and the odds ratios of agreement, four log-linear models were used: a full model, a homogeneous-margin model, a model with single odds ratio for all patients, and a model with single intercept. Then a log-linear mixed model was fitted considering the biological variability as a random effect. Among the 390,339 base-pairs sequenced, TMAP-NextGENe® and BWA-GATK found, on average, 2253.49 and 1857.14 variants (single nucleotide variants and indels), respectively. Against the gold standard, the pipelines had similar sensitivities (63.47% vs. 63.42%) and close but significantly different specificities (99.57% vs. 99.65%; p < 0.001). Same-trend results were obtained when only single nucleotide variants were considered (99.98% specificity and 76.81% sensitivity for both pipelines). The method allows thus pipeline comparison and selection. It is generalizable to all types of MPS data and all pipelines.

Global environmental effects of impact-generated aerosols: Results from a general circulation model, revision 1

NASA Technical Reports Server (NTRS)

Covey, Curt; Ghan, Steven J.; Walton, John J.; Weissman, Paul R.

1989-01-01

Interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet would lead to substantial land surface cooling, according to our three-dimensional atmospheric general circulation model (GCM). This result is qualitatively similar to conclusions drawn from an earlier study that employed a one-dimensional atmospheric model, but in the GCM simulation the heat capacity of the oceans substantially mitigates land surface cooling, an effect that one-dimensional models cannot quantify. On the other hand, the low heat capacity of the GCM's land surface allows temperatures to drop more rapidly in the initial stage of cooling than in the one-dimensional model study. These two differences between three-dimensional and one-dimensional model simulations were noted previously in studies of nuclear winter; GCM-simulated climatic changes in the Alvarez-inspired scenario of asteroid/comet winter, however, are more severe than in nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on earth. Impacts of smaller objects could also lead to dramatic, though less severe, climatic changes, according to our GCM. Our conclusion is that it is difficult to imagine an asteroid or comet impact leading to anything approaching complete global freezing, but quite reasonable to assume that impacts at the Alvarez level, or even smaller, dramatically alter the climate in at least a patchy sense.

A New Hybrid Spatio-temporal Model for Estimating Daily Multi-year PM2.5 Concentrations Across Northeastern USA Using High Resolution Aerosol Optical Depth Data

NASA Technical Reports Server (NTRS)

Kloog, Itai; Chudnovsky, Alexandra A.; Just, Allan C.; Nordio, Francesco; Koutrakis, Petros; Coull, Brent A.; Lyapustin, Alexei; Wang, Yujie; Schwartz, Joel

2014-01-01

The use of satellite-based aerosol optical depth (AOD) to estimate fine particulate matter PM(sub 2.5) for epidemiology studies has increased substantially over the past few years. These recent studies often report moderate predictive power, which can generate downward bias in effect estimates. In addition, AOD measurements have only moderate spatial resolution, and have substantial missing data. We make use of recent advances in MODIS satellite data processing algorithms (Multi-Angle Implementation of Atmospheric Correction (MAIAC), which allow us to use 1 km (versus currently available 10 km) resolution AOD data.We developed and cross validated models to predict daily PM(sub 2.5) at a 1X 1 km resolution across the northeastern USA (New England, New York and New Jersey) for the years 2003-2011, allowing us to better differentiate daily and long term exposure between urban, suburban, and rural areas. Additionally, we developed an approach that allows us to generate daily high-resolution 200 m localized predictions representing deviations from the area 1 X 1 km grid predictions. We used mixed models regressing PM(sub 2.5) measurements against day-specific random intercepts, and fixed and random AOD and temperature slopes. We then use generalized additive mixed models with spatial smoothing to generate grid cell predictions when AOD was missing. Finally, to get 200 m localized predictions, we regressed the residuals from the final model for each monitor against the local spatial and temporal variables at each monitoring site. Our model performance was excellent (mean out-of-sample R(sup 2) = 0.88). The spatial and temporal components of the out-of-sample results also presented very good fits to the withheld data (R(sup 2) = 0.87, R(sup)2 = 0.87). In addition, our results revealed very little bias in the predicted concentrations (Slope of predictions versus withheld observations = 0.99). Our daily model results show high predictive accuracy at high spatial resolutions and will be useful in reconstructing exposure histories for epidemiological studies across this region.

A New Hybrid Spatio-Temporal Model For Estimating Daily Multi-Year PM2.5 Concentrations Across Northeastern USA Using High Resolution Aerosol Optical Depth Data.

PubMed

Kloog, Itai; Chudnovsky, Alexandra A; Just, Allan C; Nordio, Francesco; Koutrakis, Petros; Coull, Brent A; Lyapustin, Alexei; Wang, Yujie; Schwartz, Joel

2014-10-01

The use of satellite-based aerosol optical depth (AOD) to estimate fine particulate matter (PM 2.5 ) for epidemiology studies has increased substantially over the past few years. These recent studies often report moderate predictive power, which can generate downward bias in effect estimates. In addition, AOD measurements have only moderate spatial resolution, and have substantial missing data. We make use of recent advances in MODIS satellite data processing algorithms (Multi-Angle Implementation of Atmospheric Correction (MAIAC), which allow us to use 1 km (versus currently available 10 km) resolution AOD data. We developed and cross validated models to predict daily PM 2.5 at a 1×1km resolution across the northeastern USA (New England, New York and New Jersey) for the years 2003-2011, allowing us to better differentiate daily and long term exposure between urban, suburban, and rural areas. Additionally, we developed an approach that allows us to generate daily high-resolution 200 m localized predictions representing deviations from the area 1×1 km grid predictions. We used mixed models regressing PM 2.5 measurements against day-specific random intercepts, and fixed and random AOD and temperature slopes. We then use generalized additive mixed models with spatial smoothing to generate grid cell predictions when AOD was missing. Finally, to get 200 m localized predictions, we regressed the residuals from the final model for each monitor against the local spatial and temporal variables at each monitoring site. Our model performance was excellent (mean out-of-sample R 2 =0.88). The spatial and temporal components of the out-of-sample results also presented very good fits to the withheld data (R 2 =0.87, R 2 =0.87). In addition, our results revealed very little bias in the predicted concentrations (Slope of predictions versus withheld observations = 0.99). Our daily model results show high predictive accuracy at high spatial resolutions and will be useful in reconstructing exposure histories for epidemiological studies across this region.

A New Hybrid Spatio-Temporal Model For Estimating Daily Multi-Year PM2.5 Concentrations Across Northeastern USA Using High Resolution Aerosol Optical Depth Data

PubMed Central

Kloog, Itai; Chudnovsky, Alexandra A.; Just, Allan C.; Nordio, Francesco; Koutrakis, Petros; Coull, Brent A.; Lyapustin, Alexei; Wang, Yujie; Schwartz, Joel

2017-01-01

Background The use of satellite-based aerosol optical depth (AOD) to estimate fine particulate matter (PM2.5) for epidemiology studies has increased substantially over the past few years. These recent studies often report moderate predictive power, which can generate downward bias in effect estimates. In addition, AOD measurements have only moderate spatial resolution, and have substantial missing data. Methods We make use of recent advances in MODIS satellite data processing algorithms (Multi-Angle Implementation of Atmospheric Correction (MAIAC), which allow us to use 1 km (versus currently available 10 km) resolution AOD data. We developed and cross validated models to predict daily PM2.5 at a 1×1km resolution across the northeastern USA (New England, New York and New Jersey) for the years 2003–2011, allowing us to better differentiate daily and long term exposure between urban, suburban, and rural areas. Additionally, we developed an approach that allows us to generate daily high-resolution 200 m localized predictions representing deviations from the area 1×1 km grid predictions. We used mixed models regressing PM2.5 measurements against day-specific random intercepts, and fixed and random AOD and temperature slopes. We then use generalized additive mixed models with spatial smoothing to generate grid cell predictions when AOD was missing. Finally, to get 200 m localized predictions, we regressed the residuals from the final model for each monitor against the local spatial and temporal variables at each monitoring site. Results Our model performance was excellent (mean out-of-sample R2=0.88). The spatial and temporal components of the out-of-sample results also presented very good fits to the withheld data (R2=0.87, R2=0.87). In addition, our results revealed very little bias in the predicted concentrations (Slope of predictions versus withheld observations = 0.99). Conclusion Our daily model results show high predictive accuracy at high spatial resolutions and will be useful in reconstructing exposure histories for epidemiological studies across this region. PMID:28966552

Barriers and dispersal surfaces in minimum-time interception. [for optimizing aircraft flight paths

NASA Technical Reports Server (NTRS)

Rajan, N.; Ardema, M. D.

1984-01-01

A method is proposed for mapping the barrier, dispersal, and control-level surfaces for a class of minimum-time interception and pursuit-evasion problems. Minimum-time interception of a target moving in a horizontal plane is formulated in a coordinate system whose origin is at the interceptor's terminal position and whose x-axis is along the terminal line of sight. This approach makes it possible to discuss the nature of the interceptor's extremals, using its extremal trajectory maps (ETMs), independently of target motion. The game surfaces are constructed by drawing sections of the isochrones, or constant minimum-time loci, from the interceptor and target ETMs. In this way, feedback solutions for the optimal controls are obtained. An example involving the interception of a target moving in a straight line at constant speed is presented.

Trajectories of Terminally Ill Patients' Cardiovascular Response to Receptive Music Therapy in Palliative Care.

PubMed

Warth, Marco; Kessler, Jens; Hillecke, Thomas K; Bardenheuer, Hubert J

2016-08-01

Relaxation interventions are frequently used to promote symptom relief in palliative care settings, but little is known about the underlying mechanisms. The present analysis aimed at examining the psychophysiological pathways of terminally ill patients' cardiovascular response to a live music therapy vs. prerecorded mindfulness exercise. Eighty-four patients of a palliative care unit were randomly assigned to either of the two interventions. Multilevel modeling was used to analyze trajectories of physiological change. Vagally mediated heart rate variability (VM-HRV) and blood volume pulse amplitude (BVP-A) served as indices of autonomic nervous system response. Participants' gender, age, baseline scores, self-rated pain, and assignment to treatment were entered to the models as predictors. Both VM-HRV and BVP-A showed significant linear and quadratic trends over time, as well as substantial heterogeneity among individuals' trajectories. Baseline scores, pain, and treatment significantly accounted for random variation in VM-HRV intercepts. BVP-A levels were significantly higher in women than in men. Moreover, assignment to treatment significantly accounted for differences in the linear slopes of peripheral blood flow. Higher levels of VM-HRV in the music therapy group highlight the importance of a therapeutic relationship for the effectiveness of relaxation interventions in end-of-life care settings. Music therapy caused significantly stronger reductions of vascular sympathetic tone and, therefore, may be indicated in the treatment of pain and stress-related symptoms in palliative care. Initial self-ratings of pain moderated patients' physiological response and need to be taken into account in clinical practice and future theory building. Copyright © 2016 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

Do HMO market level factors lead to racial/ethnic disparities in colorectal cancer screening? A comparison between high-risk Asian and Pacific Islander Americans and high-risk whites.

PubMed

Ponce, Ninez A; Huh, Soonim; Bastani, Roshan

2005-11-01

Few studies have explored health care market structure and colorectal cancer (CRC) screening test use, and little is known whether market factors contribute to racial/ethnic screening disparities. We investigated whether HMO market level factors, controlling for individual covariates, differentially impact Asian American and Pacific Islander (AAPI) subjects' access to CRC screening compared with white subjects. We used random intercept hierarchical models to predict CRC test use. Individual-level survey data was linked to market data by metropolitan statistical areas from InterStudy. Insured first-degree relatives, ages 40-80, of a random sample of colorectal cancer cases identified from the California Cancer Registry: 515 white subjects and 396 AAPI subjects residing in 36 metropolitan statistical areas (MSAs). Dependent variables were receipt of (1) annual fecal occult blood test only; (2) sigmoidoscopy in the past 5 years; (3) colonoscopy in the past 10 years; and (4) any of these tests over the recommended time interval. Market characteristics were HMO penetration, HMO competition, and proportion of staff/group/network HMOs. Market characteristics were as important as individual-level characteristics for AAPI but not for white subjects. Among AAPI subjects, a 10% increase in the percent of group/staff/network model HMO was associated with a reduction in colonoscopy use (28.9% to 20.5%) and in receipt of any of the CRC tests (53.2% to 45.4%). The prevailing organizational structure of a health care market confers a penalty on access to CRC test use among high-risk AAPI subjects but not among high-risk white subjects. Identifying the differential effect of market structure on race/ethnicity can potentially reduce the cancer burden among disadvantaged racial groups.

Moderate wine consumption is associated with lower hemostatic and inflammatory risk factors over 8 years: The study of women’s health across the nation (SWAN)

PubMed Central

Janssen, Imke; Landay, Alan L.; Ruppert, Kristine; Powell, Lynda H.

2015-01-01

Moderate wine consumption has been associated with reduced cardiovascular (CV) risk, but most investigations have been conducted in Caucasian populations. To investigate the relationship of wine consumption to CV risk markers, we studied a multi-ethnic sample of middle-aged, healthy women (N = 2900; 48% white, 28% black, 7% Hispanic, 8% Chinese, 9% Japanese) participating in SWAN over 7 years with repeated assessments of CV risk factors. Consumption of wine was stable and common with 20% reporting none, 69% light (<1/day), 7% moderate ( = 1/day), and 4% heavy (>1/day). To guard against underreporting, we took the maximum reported wine consumption over 7 years as the predictor. We used mixed models with a random intercept and random time to assess the relationship between wine consumption and CV risk factors with moderate consumption as the reference. Outcome variables were log-transformed where necessary. Longitudinal models were adjusted for ethnicity, age, and time-varying menopausal status, hormone therapy use, overall alcohol consumption, high density lipoprotein (HDL), statin use, and a healthy lifestyle score based on physical activity, not smoking, and weight maintenance. Interactions of wine consumption with time were not significant. Moderate wine consumers had significantly lower levels of C-reactive protein (CRP, p < .001), fibrinogen (p < .001), factor VII (p < .01), and plasminogen activator inhibitor (PAI-1, p < .05) than women who drank no or little wine. These associations were independent of significant effects of healthy lifestyle and overall alcohol consumption and similar across ethnic groups. Moderate wine consumption may protect against CVD via inflammatory and clotting pathways. PMID:25705320

Fermentable fibers do not affect satiety or food intake by women who do not practice restrained eating.

PubMed

Karalus, Melinda; Clark, Michelle; Greaves, Kathryn A; Thomas, William; Vickers, Zata; Kuyama, Megumi; Slavin, Joanne

2012-09-01

Fiber is thought to enhance satiety, although not all fibers are equally effective. Colonic fermentation may influence satiety and food intake. To test the satiating properties of four isolated fibers added to chocolate crisp bars. Within-subject preload design with repeated measures. Each participant completed five conditions, presented in random order. Participants were 22 adult women who do not practice restrained eating (body mass index 18 to 29). The experimental conditions were four fiber treatments: 10 g oligofructose, inulin, soluble corn fiber, or resistant wheat starch in chocolate crisp bars. A no-added-fiber bar was evaluated as the control. The night before each treatment, participants consumed a dinner bar containing 10 g of the same fiber given the next morning. Repeated ratings of feelings related to hunger and fullness at the lunch meal were the main measures. Secondary outcomes included breath hydrogen and methane, gastrointestinal symptoms, energy consumed at an ad libitum lunch, and energy from 24-hour dietary recall. Mixed-effect linear models with random intercept for participants to model within-subject correlation. All treatments were well tolerated. No differences were found in subjective satiety during the morning or food intake at lunch or over 24 hours. The oligofructose bar produced the greatest increase in breath hydrogen, and the most bloating and flatulence symptoms. Functional fibers incorporated into chocolate bars at high fiber doses produce greater gastrointestinal symptoms than control, but do not alter satiety, hunger, or food intake compared with control in the short term. Copyright © 2012 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

Factors which modulate the rates of skeletal muscle mass loss in non-small cell lung cancer patients: a pilot study.

PubMed

Atlan, Philippe; Bayar, Mohamed Amine; Lanoy, Emilie; Besse, Benjamin; Planchard, David; Ramon, Jordy; Raynard, Bruno; Antoun, Sami

2017-11-01

Advanced non-small cell lung cancer (NSCLC) is associated with weight loss which may reflect skeletal muscle mass (SMM) and/or total adipose tissue (TAT) depletion. This study aimed to describe changes in body composition (BC) parameters and to identify the factors unrelated to the tumor which modulate them. SMM, TAT, and the proportion of SMM to SMM + TAT were assessed with computed tomography. Estimates of each BC parameter at follow-up initiation and across time were derived from a mixed linear model of repeated measurements with a random intercept and a random slope. The same models were used to assess the independent effect of gender, age, body mass index (BMI), and initial values on changes in each BC parameter. Sixty-four patients with stage III or IV NSCLC were reviewed. The mean ± SD decreases in body weight and SMM were respectively 59 ± 3 g/week (P < 0.03) and 7 mm 2 /m 2 /week (P = 0.0003). During follow-up, no changes were identified in TAT nor in muscle density or in the proportion of SMM to SMM + TAT, estimated at 37 ± 2% at baseline. SMM loss was influenced by initial BMI (P < 0.0001) and SMM values (P = 0.0002): the higher the initial BMI or SMM values, the greater the loss observed. Weight loss was greater when the initial weight was heavier (P < 0.0001). Our results demonstrate that SMM wasting in NSCLC is lower when initial SMM and BMI values are low. These exploratory findings after our attempt to better understand the intrinsic factors associated with muscle mass depletion need to be confirmed in larger studies.

Vegetation pattern formation in a fog-dependent ecosystem.

PubMed

Borthagaray, Ana I; Fuentes, Miguel A; Marquet, Pablo A

2010-07-07

Vegetation pattern formation is a striking characteristic of several water-limited ecosystems around the world. Typically, they have been described on runoff-based ecosystems emphasizing local interactions between water, biomass interception, growth and dispersal. Here, we show that this situation is by no means general, as banded patterns in vegetation can emerge in areas without rainfall and in plants without functional root (the Bromeliad Tillandsia landbeckii) and where fog is the principal source of moisture. We show that a simple model based on the advection of fog-water by wind and its interception by the vegetation can reproduce banded patterns which agree with empirical patterns observed in the Coastal Atacama Desert. Our model predicts how the parameters may affect the conditions to form the banded pattern, showing a transition from a uniform vegetated state, at high water input or terrain slope to a desert state throughout intermediate banded states. Moreover, the model predicts that the pattern wavelength is a decreasing non-linear function of fog-water input and slope, and an increasing function of plant loss and fog-water flow speed. Finally, we show that the vegetation density is increased by the formation of the regular pattern compared to the density expected by the spatially homogeneous model emphasizing the importance of self-organization in arid ecosystems. (c) 2010 Elsevier Ltd. All rights reserved.

A simple method for assessment of muscle force, velocity, and power producing capacities from functional movement tasks.

PubMed

Zivkovic, Milena Z; Djuric, Sasa; Cuk, Ivan; Suzovic, Dejan; Jaric, Slobodan

2017-07-01

A range of force (F) and velocity (V) data obtained from functional movement tasks (e.g., running, jumping, throwing, lifting, cycling) performed under variety of external loads have typically revealed strong and approximately linear F-V relationships. The regression model parameters reveal the maximum F (F-intercept), V (V-intercept), and power (P) producing capacities of the tested muscles. The aim of the present study was to evaluate the level of agreement between the routinely used "multiple-load model" and a simple "two-load model" based on direct assessment of the F-V relationship from only 2 external loads applied. Twelve participants were tested on the maximum performance vertical jumps, cycling, bench press throws, and bench pull performed against a variety of different loads. All 4 tested tasks revealed both exceptionally strong relationships between the parameters of the 2 models (median R = 0.98) and a lack of meaningful differences between their magnitudes (fixed bias below 3.4%). Therefore, addition of another load to the standard tests of various functional tasks typically conducted under a single set of mechanical conditions could allow for the assessment of the muscle mechanical properties such as the muscle F, V, and P producing capacities.

Community mass treatment with azithromycin for trachoma: Factors associated with change in participation of children from the first to the second round

PubMed Central

Ssemanda, Elizabeth N.; Mkocha, Harran; Levens, Joshua; Munoz, Beatriz; West, Sheila K.

2013-01-01

Background Mass drug administration (MDA) with azithromycin is an important part of trachoma control programs. Maintaining high participation among children is challenging. Aim We assessed factors identifying households with a child who changed participation from the first MDA to the second MDA compared to households where all children participated at both MDAs. Methods Two case-control comparisons were conducted in 11 Tanzanian communities, which underwent MDA in 2008 and 2009. The first case group (n=165) was a random sample of households with a child who changed from a 2008 non-participant to a 2009 participant (delayed participant). The second case group (n=165) was a random sample of households with a child who went from a 2008 participant to a 2009 non-participant (change to non-participant). Controls (n=330) were a random sample of households where all children participated in both rounds. Risk factors were assessed using questionnaires asked of children’s guardians. Logistic models with a random-intercept were used to estimate odds ratios and 95% confidence intervals. Results Households with delayed participation were more likely to be in communities with fewer treatment days (OR=2.98, 95% CI=1.80–4.92) and assigned to Community Treatment Assistants (CTA) with a wide area to cover (OR=1.88, 95% CI=1.09–3.23). Households with change to non-participation were more likely to live further from the distribution site (OR=3.17, 95% CI=1.19–8.46), have the guardian born outside the village with short-term residency (OR=2.64, 95% CI=1.32–5.31), and be assigned to a male CTA (OR=1.75, 95% CI=1.08–2.83). Conclusions Factors related to program accessibility were associated with delayed participation and maintaining participation. PMID:26462290

Linking ice accretion and crown structure: towards a model of the effect of freezing rain on tree canopies.

PubMed

Nock, Charles A; Lecigne, Bastien; Taugourdeau, Olivier; Greene, David F; Dauzat, Jean; Delagrange, Sylvain; Messier, Christian

2016-06-01

Despite a longstanding interest in variation in tree species vulnerability to ice storm damage, quantitative analyses of the influence of crown structure on within-crown variation in ice accretion are rare. In particular, the effect of prior interception by higher branches on lower branch accumulation remains unstudied. The aim of this study was to test the hypothesis that intra-crown ice accretion can be predicted by a measure of the degree of sheltering by neighbouring branches. Freezing rain was artificially applied to Acer platanoides L., and in situ branch-ice thickness was measured directly and from LiDAR point clouds. Two models of freezing rain interception were developed: 'IceCube', which uses point clouds to relate ice accretion to a voxel-based index (sheltering factor; SF) of the sheltering effect of branch elements above a measurement point; and 'IceTree', a simulation model for in silico evaluation of the interception pattern of freezing rain in virtual tree crowns. Intra-crown radial ice accretion varied strongly, declining from the tips to the bases of branches and from the top to the base of the crown. SF for branches varied strongly within the crown, and differences among branches were consistent for a range of model parameters. Intra-crown variation in ice accretion on branches was related to SF (R(2) = 0·46), with in silico results from IceTree supporting empirical relationships from IceCube. Empirical results and simulations confirmed a key role for crown architecture in determining intra-crown patterns of ice accretion. As suspected, the concentration of freezing rain droplets is attenuated by passage through the upper crown, and thus higher branches accumulate more ice than lower branches. This is the first step in developing a model that can provide a quantitative basis for investigating intra-crown and inter-specific variation in freezing rain damage. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Indirect interception actions by blind and visually impaired perceivers: echolocation for interceptive actions.

PubMed

Vernat, Jean-Philippe; Gordon, Michael S

2010-02-01

This research examined the acoustic information used to support interceptive actions by the blind. Congenitally blind and severely visually impaired participants (all wearing an opaque, black eye-mask) were asked to listen to a target ball rolling down a track. In response, participants rolled their own ball along a perpendicular path to intercept the target. To better understand what information was used the echoic conditions and rolling dynamics of the target were varied across test sessions. In addition the rolling speed of the target and the distance of the participant from the target were varied across trials. Results demonstrated that participants tended to perform most accurately at moderate speeds and distances, overestimating the target's arrival at the fastest speed, and underestimating it at the slowest speed. However, changes to the target's dynamics, that is, the amount of deceleration it underwent on approach, did not strongly influence performance. Echoic conditions were found to affect performance, as participants were slightly more accurate in conditions with faster, higher-intensity echoes. Based on these results blind individuals in this research seemed to be using spatial and temporal cues to coordinate their interceptive actions.

Traveler information services in rural tourism areas : appendix A, tourist intercept surveys

DOT National Transportation Integrated Search

2000-06-30

This document presents documentation regarding tourist intercept surveys for traveler information services in rural areas. It documents data collection functions and information dissemination functions, and provides an interpretive description of tra...

Contaminant point source localization error estimates as functions of data quantity and model quality

NASA Astrophysics Data System (ADS)

Hansen, Scott K.; Vesselinov, Velimir V.

2016-10-01

We develop empirically-grounded error envelopes for localization of a point contamination release event in the saturated zone of a previously uncharacterized heterogeneous aquifer into which a number of plume-intercepting wells have been drilled. We assume that flow direction in the aquifer is known exactly and velocity is known to within a factor of two of our best guess from well observations prior to source identification. Other aquifer and source parameters must be estimated by interpretation of well breakthrough data via the advection-dispersion equation. We employ high performance computing to generate numerous random realizations of aquifer parameters and well locations, simulate well breakthrough data, and then employ unsupervised machine optimization techniques to estimate the most likely spatial (or space-time) location of the source. Tabulating the accuracy of these estimates from the multiple realizations, we relate the size of 90% and 95% confidence envelopes to the data quantity (number of wells) and model quality (fidelity of ADE interpretation model to actual concentrations in a heterogeneous aquifer with channelized flow). We find that for purely spatial localization of the contaminant source, increased data quantities can make up for reduced model quality. For space-time localization, we find similar qualitative behavior, but significantly degraded spatial localization reliability and less improvement from extra data collection. Since the space-time source localization problem is much more challenging, we also tried a multiple-initial-guess optimization strategy. This greatly enhanced performance, but gains from additional data collection remained limited.

Dual representation of item positions in verbal short-term memory: Evidence for two access modes.

PubMed

Lange, Elke B; Verhaeghen, Paul; Cerella, John

Memory sets of N = 1~5 digits were exposed sequentially from left-to-right across the screen, followed by N recognition probes. Probes had to be compared to memory list items on identity only (Sternberg task) or conditional on list position. Positions were probed randomly or in left-to-right order. Search functions related probe response times to set size. Random probing led to ramped, "Sternbergian" functions whose intercepts were elevated by the location requirement. Sequential probing led to flat search functions-fast responses unaffected by set size. These results suggested that items in STM could be accessed either by a slow search-on-identity followed by recovery of an associated location tag, or in a single step by following item-to-item links in study order. It is argued that this dual coding of location information occurs spontaneously at study, and that either code can be utilised at retrieval depending on test demands.

Optimal feedback strategies for pursuit-evasion and interception in a plane

NASA Technical Reports Server (NTRS)

Rajan, N.; Ardema, M. D.

1983-01-01

Variable-speed pursuit-evasion and interception for two aircraft moving in a horizontal plane are analyzed in terms of a coordinate frame fixed in the plane at termination. Each participant's optimal motion can be represented by extremal trajectory maps. These maps are used to discuss sub-optimal approximations that are independent of the other participant. A method of constructing sections of the barrier, dispersal, and control-level surfaces and thus determining feedback strategies is described. Some examples are shown for pursuit-evasion and the minimum-time interception of a straight-flying target.

Proceedings of the Near-Earth-Object Interception Workshop

NASA Technical Reports Server (NTRS)

Canavan, G. J. (Editor); Solem, J. C. (Editor); Rather, John D. G. (Editor)

1993-01-01

The National Aeronautics and Space Administration Headquarters sponsored the Near-Earth-Object Interception Workshop hosted by the Los Alamos National Laboratory on 14-16 Jan. 1992 at the J. Robert Oppenheimer Study Center in Los Alamos, New Mexico. The Workshop evaluated the issues involved in intercepting celestial objects that could hit the Earth. It covered the technologies for acquiring, tracking, and homing, as well as those for sending interceptors to inspect, rendezvous with, land on, irradiate, deflect, or destroy them. This report records the presentations and technical options reviewed.

Regression calibration for models with two predictor variables measured with error and their interaction, using instrumental variables and longitudinal data.

PubMed

Strand, Matthew; Sillau, Stefan; Grunwald, Gary K; Rabinovitch, Nathan

2014-02-10

Regression calibration provides a way to obtain unbiased estimators of fixed effects in regression models when one or more predictors are measured with error. Recent development of measurement error methods has focused on models that include interaction terms between measured-with-error predictors, and separately, methods for estimation in models that account for correlated data. In this work, we derive explicit and novel forms of regression calibration estimators and associated asymptotic variances for longitudinal models that include interaction terms, when data from instrumental and unbiased surrogate variables are available but not the actual predictors of interest. The longitudinal data are fit using linear mixed models that contain random intercepts and account for serial correlation and unequally spaced observations. The motivating application involves a longitudinal study of exposure to two pollutants (predictors) - outdoor fine particulate matter and cigarette smoke - and their association in interactive form with levels of a biomarker of inflammation, leukotriene E4 (LTE 4 , outcome) in asthmatic children. Because the exposure concentrations could not be directly observed, we used measurements from a fixed outdoor monitor and urinary cotinine concentrations as instrumental variables, and we used concentrations of fine ambient particulate matter and cigarette smoke measured with error by personal monitors as unbiased surrogate variables. We applied the derived regression calibration methods to estimate coefficients of the unobserved predictors and their interaction, allowing for direct comparison of toxicity of the different pollutants. We used simulations to verify accuracy of inferential methods based on asymptotic theory. Copyright © 2013 John Wiley & Sons, Ltd.

Association of incidental emphysema with annual lung function decline and future development of airflow limitation

PubMed Central

Koo, Hyeon-Kyoung; Jin, Kwang Nam; Kim, Deog Kyeom; Chung, Hee Soon; Lee, Chang-Hoon

2016-01-01

Objectives Emphysema is one of the prognostic factors for rapid lung function decline in patients with COPD, but the impact of incidentally detected emphysema on population without spirometric abnormalities has not been evaluated. This study aimed to determine whether emphysema detected upon computed tomography (CT) screening would accelerate the rate of lung function decline and influence the possibility of future development of airflow limitation in a population without spirometric abnormalities. Materials and methods Subjects who participated in a routine screening for health checkup and follow-up pulmonary function tests for at least 3 years between 2004 and 2010 were retrospectively enrolled. The percentage of low-attenuation area below −950 Hounsfield units (%LAA−950) was calculated automatically. A calculated value of %LAA−950 that exceeded 10% was defined as emphysema. Adjusted annual lung function decline was analyzed using random-slope, random-intercept mixed linear regression models. Results A total of 628 healthy subjects within the normal range of spriometric values were included. Multivariable analysis showed that the emphysema group exhibited a faster decline in forced vital capacity (−33.9 versus −18.8 mL/year; P=0.02). Emphysema was not associated with the development of airflow limitation during follow-up. Conclusion Incidental emphysema quantified using CT scan was significantly associated with a more rapid decline in forced vital capacity in the population with normative spirometric values. However, an association between emphysema and future development of airflow limitation was not observed. PMID:26893550

Bullying, Social Support, and Psychological Distress: Findings From RELACHS Cohorts of East London's White British and Bangladeshi Adolescents.

PubMed

Bhui, Kamaldeep; Silva, Maria Joao; Harding, Seeromanie; Stansfeld, Stephen

2017-09-01

The purpose of the study is to test whether bullying in adolescents relates to poor mental health and whether social support mitigated this effect. In 2001, 28 schools in East London were randomly selected for surveys of two representative mixed ability classes: year 7 (11-12 years) and year 9 (13-14 years). Repeated measures were obtained from the same pupils 2 years later, using the Strengths and Difficulties Questionnaire (total difficulties score [TDS]) as a measure of psychological distress. A simple one-level random intercepts model with measurements nested within pupils was used to investigate the effects of bullying and social support from friends and family on TDS. We also assessed whether culturally congruent friendships offered a mental health advantage. Bullying was associated with a higher mean TDS (coefficient, 95% confidence interval: White British: 2.15, 1.41-2.88; Bangladeshi: 1.65, .91-2.4); a high level of family social support was associated with a lower TDS (White British: -2.36, -3.33 to -1.39; Bangladeshi: -2.34, -3.15 to -.149). Social support from friends was helpful for White British adolescents (-1.06, -2.07 to -.04). Culturally congruent friendships offered no general advantage. Bullying is associated with psychological distress; family social support is independently associated with less psychological distress. Copyright © 2017 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

A note on the temporal behavior of bucket hydrologies

NASA Technical Reports Server (NTRS)

Suarez, M. J.

1984-01-01

The use of a "canopy' bucket to more accurately represent evapotranspiration over land surfaces is explained. The temporal behavior of the traditional bucket model is compared with one that mimics the effects of interception loss. Results are presented in terms of the spectral response of the parameterization to a hypothetical white noise forcing.

Does spatial arrangement of 3D plants affect light transmission and extinction coefficient within maize crops?

USDA-ARS?s Scientific Manuscript database

Row spacing effects on light interception and extinction coefficient have been inconsistent for maize (Zea mays L.) when calculated with field measurements. To avoid inconsistencies due to variable light conditions and variable leaf canopies, we used a model to describe three-dimensional (3D) shoot ...

Testing Measurement Invariance Using MIMIC: Likelihood Ratio Test with a Critical Value Adjustment

ERIC Educational Resources Information Center

Kim, Eun Sook; Yoon, Myeongsun; Lee, Taehun

2012-01-01

Multiple-indicators multiple-causes (MIMIC) modeling is often used to test a latent group mean difference while assuming the equivalence of factor loadings and intercepts over groups. However, this study demonstrated that MIMIC was insensitive to the presence of factor loading noninvariance, which implies that factor loading invariance should be…

Modeling the Interaction Between Hydraulic and Natural Fractures Using Dual-Lattice Discrete Element Method

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

Zhou, Jing; Huang, Hai; Deo, Milind

The interaction between hydraulic fractures (HF) and natural fractures (NF) will lead to complex fracture networks due to the branching and merging of natural and hydraulic fractures in unconventional reservoirs. In this paper, a newly developed hydraulic fracturing simulator based on discrete element method is used to predict the generation of complex fracture network in the presence of pre-existing natural fractures. By coupling geomechanics and reservoir flow within a dual lattice system, this simulator can effectively capture the poro-elastic effects and fluid leakoff into the formation. When HFs are intercepting single or multiple NFs, complex mechanisms such as direct crossing,more » arresting, dilating and branching can be simulated. Based on the model, the effects of injected fluid rate and viscosity, the orientation and permeability of NFs and stress anisotropy on the HF-NF interaction process are investigated. Combined impacts from multiple parameters are also examined in the paper. The numerical results show that large values of stress anisotropy, intercepting angle, injection rate and viscosity will impede the opening of NFs.« less

Investigation of Vapor Cooling Enhancements for Applications on Large Cryogenic Systems

NASA Technical Reports Server (NTRS)

Ameen, Lauren; Zoeckler, Joseph

2017-01-01

The need to demonstrate and evaluate the effectiveness of heat interception methods for use on a relevant cryogenic propulsion stage at a system level has been identified. Evolvable Cryogenics (eCryo) Structural Heat Intercept, Insulation and Vibration Evaluation Rig (SHIIVER) will be designed with vehicle specific geometries (SLS Exploration Upper Stage (EUS) as guidance) and will be subjected to simulated space environments. One method of reducing structure-born heat leak being investigated utilizes vapor-based heat interception. Vapor-based heat interception could potentially reduce heat leak into liquid hydrogen propulsion tanks, increasing potential mission length or payload capability. Due to the high number of unknowns associated with the heat transfer mechanism and integration of vapor-based heat interception on a realistic large-scale skirt design, a sub-scale investigation was developed. The sub-project effort is known as the Small-scale Laboratory Investigation of Cooling Enhancements (SLICE). The SLICE aims to study, design, and test sub-scale multiple attachments and flow configuration concepts for vapor-based heat interception of structural skirts. SLICE will focus on understanding the efficiency of the heat transfer mechanism to the boil-off hydrogen vapor by varying the fluid network designs and configurations. Various analyses were completed in MATLAB, Excel VBA, and COMSOL Multiphysics to understand the optimum flow pattern for heat transfer and fluid dynamics. Results from these analyses were used to design and fabricate test article subsections of a large forward skirt with vapor cooling applied. The SLICE testing is currently being performed to collect thermal mechanical performance data on multiple skirt heat removal designs while varying inlet vapor conditions necessary to intercept a specified amount of heat for a given system. Initial results suggest that applying vapor-cooling provides a 50 heat reduction in conductive heat transmission along the skirt to the tank. The information obtained by SLICE will be used by the SHIIVER engineering team to design and implement vapor-based heat removal technology into the SHIIVER forward skirt hardware design.

40 CFR 53.34 - Test procedure for methods for PM10 and Class I methods for PM2.5.

Code of Federal Regulations, 2011 CFR

2011-07-01

... linear regression parameters (slope, intercept, and correlation coefficient) describing the relationship... correlation coefficient. (2) To pass the test for comparability, the slope, intercept, and correlation...

Intercepting real and simulated falling objects: what is the difference?

PubMed

Baurès, Robin; Benguigui, Nicolas; Amorim, Michel-Ange; Hecht, Heiko

2009-10-30

The use of virtual reality is nowadays common in many studies in the field of human perception and movement control, particularly in interceptive actions. However, the ecological validity of the simulation is often taken for granted without having been formally established. If participants were to perceive the real situation and its virtual equivalent in a different fashion, the generalization of the results obtained in virtual reality to real life would be highly questionable. We tested the ecological validity of virtual reality in this context by comparing the timing of interceptive actions based upon actually falling objects and their simulated counterparts. The results show very limited differences as a function of whether participants were confronted with a real ball or a simulation thereof. And when present, such differences were limited to the first trial only. This result validates the use of virtual reality when studying interceptive actions of accelerated stimuli.

The use of Mediterranean shrub to flight against the land degradation. The rainfall partitioning fluxes

NASA Astrophysics Data System (ADS)

García-Estringana, Pablo; Nieves Alonso-Blazquez, M.; Alegre, Jesús; Cerdà, Artemi

2014-05-01

Desertification can be triggered by the lost of vegetation (Izzo et al., 2013). One of the impacts of the lack of vegetation is the increase in the effective rainfall and then higher soil and water losses. Vegetation can reduce the effective rainfall by interception. To recover the land that is affected by Desertification we must select plant species that will intercept the rainfall, but will not avoid the rainfall to reach the soil. This is why, studies on the plant rainfall interception are relevant to flight Land Degradation processes. Soil erosion is highly dependent on the effective rainfall (Cerdà and Lasanta, 2005; Haile and Fetene; 2012; Miao et al., 2012, Prokop and Poręba, 2012). The amount of rainfall that reaches the soil surface and can contribute to detach and transport material is determined by the interception of plants. Interception is also a key factor of the watershed hydrology (Zema et al., 2012). The importance of the rainfall partitioning fluxes is related to the climatic conditions, as climate control the plant cover and the soil properties, and then the soil losses (Cerdà, 1998). Although the shrubs has been seen as a key vegetation cover in semiarid lands to control the soil and water losses (Cerdà and Doerr, 2007) little information is available about rainfall interception in Mediterranean shrub vegetation, due to technical difficulties to measure them in such small-sized vegetation (Belmonte Serrato and Romero Diaz, 1998). The aim of this work was to assess the influence of different Mediterranean shrubs (Retama sphaerocarpa, Colutea arborescens, Dorycnium pentaphyllum, Medicago strasseri, Pistacia Lentiscus and Quercus coccifera) on rainfall partitioning fluxes (interception losses, throughfall and stemflow) in semiarid environments. The experiment was carried out under natural rainfall conditions with live specimens during two years, with automatic measurement of rainfall partitioning fluxes. In order to assess the influence of biotic and abiotic factors on rainfall partitioning fluxes and their seasonal variation, twenty rainfall events, ten small-size events (P≤10 mm) and ten major events (P>10 mm), were selected. Great differences were observed among species, with interception losses varying between 10% for R. sphaerocarpa to greater than 36% for D. pentaphyllum and M. strasseri, and with stemflow percentages changing between less than 11% for D. pentaphyllum and M. strasseri and 20% for R. sphaerocarpa (Garcia-Estringana, 2011). Pistacia Lentiscus intercepted 21 % of the rainfall and Quercus coccifera 31 %. Species was the most important biotic factor, rainfall volume was the most significant abiotic factor. Stemflow percentages increased and interception losses percentages decreased as rainfall volume increased, both until a stable value reached when rainfall volume was greater than 10 mm. Stemflow and interception losses varied greatly in small events, consequently it is difficult to predict rainfall interception fluxes in semiarid regions, where small events are the most frequent ones. Rainfall volume events greater than 10 mm are much less frequent, but more rainfall is concentrated around the stem base, being during these events when species which used stemflow as an adaptive mechanism to aridity store water in deep soil layers. Stemflow reached their maximum values in autumn and winter, and their minimum values in summer, unlike interception losses, which were higher in summer, except for M. strasseri because it sheds all its leaves. Hydrologic impact of shrubs was very variable depending on the species, and its capacity to form dense communities. Therefore it makes this type of vegetation of great interest in the Mediterranean region, not only by the effect on soil protection (Garcia-Estringana et al., 2010), but also by the effect on hydrology and water availability in a region where water is a scarce resource and shrub vegetation is proliferating as a result of agricultural abandonment. Acknowledgements TThe research projects 07 M/0077/1998, 07 M/0023/2000 and RTA01-078-C2- 2, GL2008-02879/BTE, LEDDRA243857 and RECARE FP7 project 603498 supported this research. References: Belmonte Serrato, F., Romero Díaz, A. 1998. A simple technique for measuring rainfall interception by small shrub: "interception flow collection box. Hydrological Processes 12, 471-481. Cerdà, A. 1998. Relationship between climate and soil hydrological and erosional characteristics along climatic gradients in Mediterranean limestone areas. Geomorphology, 25, 123-134. Cerdà, A., Doerr, S.H. 2007. Soil wettability, runoff and erodibility of major dry-Mediterranean land use types on calcareous soils. Hydrological Processes, 21, 2325-2336. doi: 10.1016/j.catena.2008.03.010. Cerdà, A., Lasanta, A. 2005. Long-term erosional responses after fire in the Central Spanish Pyrenees: 1. Water and sediment yield. Catena, 60, 59-80. Garcia-Estringana, P. 2011. Efectos de diferentes tipos de vegetación mediterránea sobre la hidrología y la pérdida de suelo. Tesis Doctoral, Universidad de Alcalá, Facultad de Ciencias, pp. 170. Garcia-Estringana, P., Alonso-Blázquez, N., Marques, M.J., Bienes, R., Alegre, J. 2010. Direct and indirect effects of Mediterranean vegetation on runoff and soil loss. European Journal of Soil Science 61, 174-185. Izzo, M., Araujo, N., Aucelli, P. P. C., Maratea, A., and Sánchez, A. 2013. Land sensitivity to Desertification in the Dominican Republic: an adaptation of the ESA methodology. Land Degradation & Development, 24: 486- 498. DOI 10.1002/ldr.2241 Lasanta, A., Cerdà, A. 2005. Long-term erosional responses after fire in the Central Spanish Pyrenees: 2. Solute release. Catena, 60, 80-101 Miao, C. Y., Yang, L., Chen, X. H., Gao, Y. 2012. The vegetation cover dynamics (1982-2006) in different erosion regions of the Yellow River Basin, China. Land Degradation & Development, 23: 62- 71. DOI 10.1002/ldr.1050 Prokop, P., Poręba, G. J. 2012. Soil erosion associated with an upland farming system under population pressure in Northeast India. Land Degradation & Development, 23: 310- 321. DOI 10.1002/ldr.2147 Zema, D. A., Bingner, R. L., Denisi, P., Govers, G., Licciardello, F., Zimbone, S. M. 2012. Evaluation of runoff, peak flow and sediment yield for events simulated by the AnnAGNPS model in a belgian agricultural watershed. Land Degradation & Development, 23: 205- 215. DOI 10.1002/ldr.1068

Modeling interface roughness scattering in a layered seabed for normal-incident chirp sonar signals.

PubMed

Tang, Dajun; Hefner, Brian T

2012-04-01

Downward looking sonar, such as the chirp sonar, is widely used as a sediment survey tool in shallow water environments. Inversion of geo-acoustic parameters from such sonar data precedes the availability of forward models. An exact numerical model is developed to initiate the simulation of the acoustic field produced by such a sonar in the presence of multiple rough interfaces. The sediment layers are assumed to be fluid layers with non-intercepting rough interfaces.

Factor structure and longitudinal measurement invariance of the demand control support model: an evidence from the Swedish Longitudinal Occupational Survey of Health (SLOSH).

PubMed

Chungkham, Holendro Singh; Ingre, Michael; Karasek, Robert; Westerlund, Hugo; Theorell, Töres

2013-01-01

To examine the factor structure and to evaluate the longitudinal measurement invariance of the demand-control-support questionnaire (DCSQ), using the Swedish Longitudinal Occupational Survey of Health (SLOSH). A confirmatory factor analysis (CFA) and multi-group confirmatory factor analysis (MGCFA) models within the framework of structural equation modeling (SEM) have been used to examine the factor structure and invariance across time. Four factors: psychological demand, skill discretion, decision authority and social support, were confirmed by CFA at baseline, with the best fit obtained by removing the item repetitive work of skill discretion. A measurement error correlation (0.42) between work fast and work intensively for psychological demands was also detected. Acceptable composite reliability measures were obtained except for skill discretion (0.68). The invariance of the same factor structure was established, but caution in comparing mean levels of factors over time is warranted as lack of intercept invariance was evident. However, partial intercept invariance was established for work intensively. Our findings indicate that skill discretion and decision authority represent two distinct constructs in the retained model. However removing the item repetitive work along with either work fast or work intensively would improve model fit. Care should also be taken while making comparisons in the constructs across time. Further research should investigate invariance across occupations or socio-economic classes.

Factor Structure and Longitudinal Measurement Invariance of the Demand Control Support Model: An Evidence from the Swedish Longitudinal Occupational Survey of Health (SLOSH)

PubMed Central

Chungkham, Holendro Singh; Ingre, Michael; Karasek, Robert; Westerlund, Hugo; Theorell, Töres

2013-01-01

Objectives To examine the factor structure and to evaluate the longitudinal measurement invariance of the demand-control-support questionnaire (DCSQ), using the Swedish Longitudinal Occupational Survey of Health (SLOSH). Methods A confirmatory factor analysis (CFA) and multi-group confirmatory factor analysis (MGCFA) models within the framework of structural equation modeling (SEM) have been used to examine the factor structure and invariance across time. Results Four factors: psychological demand, skill discretion, decision authority and social support, were confirmed by CFA at baseline, with the best fit obtained by removing the item repetitive work of skill discretion. A measurement error correlation (0.42) between work fast and work intensively for psychological demands was also detected. Acceptable composite reliability measures were obtained except for skill discretion (0.68). The invariance of the same factor structure was established, but caution in comparing mean levels of factors over time is warranted as lack of intercept invariance was evident. However, partial intercept invariance was established for work intensively. Conclusion Our findings indicate that skill discretion and decision authority represent two distinct constructs in the retained model. However removing the item repetitive work along with either work fast or work intensively would improve model fit. Care should also be taken while making comparisons in the constructs across time. Further research should investigate invariance across occupations or socio-economic classes. PMID:23950957

Modeling coding-sequence evolution within the context of residue solvent accessibility.

PubMed

Scherrer, Michael P; Meyer, Austin G; Wilke, Claus O

2012-09-12

Protein structure mediates site-specific patterns of sequence divergence. In particular, residues in the core of a protein (solvent-inaccessible residues) tend to be more evolutionarily conserved than residues on the surface (solvent-accessible residues). Here, we present a model of sequence evolution that explicitly accounts for the relative solvent accessibility of each residue in a protein. Our model is a variant of the Goldman-Yang 1994 (GY94) model in which all model parameters can be functions of the relative solvent accessibility (RSA) of a residue. We apply this model to a data set comprised of nearly 600 yeast genes, and find that an evolutionary-rate ratio ω that varies linearly with RSA provides a better model fit than an RSA-independent ω or an ω that is estimated separately in individual RSA bins. We further show that the branch length t and the transition-transverion ratio κ also vary with RSA. The RSA-dependent GY94 model performs better than an RSA-dependent Muse-Gaut 1994 (MG94) model in which the synonymous and non-synonymous rates individually are linear functions of RSA. Finally, protein core size affects the slope of the linear relationship between ω and RSA, and gene expression level affects both the intercept and the slope. Structure-aware models of sequence evolution provide a significantly better fit than traditional models that neglect structure. The linear relationship between ω and RSA implies that genes are better characterized by their ω slope and intercept than by just their mean ω.

Diurnal fluctuations in brain volume: Statistical analyses of MRI from large populations.

PubMed

Nakamura, Kunio; Brown, Robert A; Narayanan, Sridar; Collins, D Louis; Arnold, Douglas L

2015-09-01

We investigated fluctuations in brain volume throughout the day using statistical modeling of magnetic resonance imaging (MRI) from large populations. We applied fully automated image analysis software to measure the brain parenchymal fraction (BPF), defined as the ratio of the brain parenchymal volume and intracranial volume, thus accounting for variations in head size. The MRI data came from serial scans of multiple sclerosis (MS) patients in clinical trials (n=755, 3269 scans) and from subjects participating in the Alzheimer's Disease Neuroimaging Initiative (ADNI, n=834, 6114 scans). The percent change in BPF was modeled with a linear mixed effect (LME) model, and the model was applied separately to the MS and ADNI datasets. The LME model for the MS datasets included random subject effects (intercept and slope over time) and fixed effects for the time-of-day, time from the baseline scan, and trial, which accounted for trial-related effects (for example, different inclusion criteria and imaging protocol). The model for ADNI additionally included the demographics (baseline age, sex, subject type [normal, mild cognitive impairment, or Alzheimer's disease], and interaction between subject type and time from baseline). There was a statistically significant effect of time-of-day on the BPF change in MS clinical trial datasets (-0.180 per day, that is, 0.180% of intracranial volume, p=0.019) as well as the ADNI dataset (-0.438 per day, that is, 0.438% of intracranial volume, p<0.0001), showing that the brain volume is greater in the morning. Linearly correcting the BPF values with the time-of-day reduced the required sample size to detect a 25% treatment effect (80% power and 0.05 significance level) on change in brain volume from 2 time-points over a period of 1year by 2.6%. Our results have significant implications for future brain volumetric studies, suggesting that there is a potential acquisition time bias that should be randomized or statistically controlled to account for the day-to-day brain volume fluctuations. Copyright © 2015 Elsevier Inc. All rights reserved.

Are the average gait speeds during the 10meter and 6minute walk tests redundant in Parkinson disease?

PubMed

Duncan, Ryan P; Combs-Miller, Stephanie A; McNeely, Marie E; Leddy, Abigail L; Cavanaugh, James T; Dibble, Leland E; Ellis, Terry D; Ford, Matthew P; Foreman, K Bo; Earhart, Gammon M

2017-02-01

We investigated the relationships between average gait speed collected with the 10Meter Walk Test (Comfortable and Fast) and 6Minute Walk Test (6MWT) in 346 people with Parkinson disease (PD) and how the relationships change with increasing disease severity. Pearson correlation and linear regression analyses determined relationships between 10Meter Walk Test and 6MWT gait speed values for the entire sample and for sub-samples stratified by Hoehn & Yahr (H&Y) stage I (n=53), II (n=141), III (n=135) and IV (n=17). We hypothesized that redundant tests would be highly and significantly correlated (i.e. r>0.70, p<0.05) and would have a linear regression model slope of 1 and intercept of 0. For the entire sample, 6MWT gait speed was significantly (p<0.001) related to the Comfortable 10 Meter Walk Test (r=0.75) and Fast 10Meter Walk Test (r=0.79) gait speed, with 56% and 62% of the variance in 6MWT gait speed explained, respectively. The regression model of 6MWT gait speed predicted by Comfortable 10 Meter Walk gait speed produced slope and intercept values near 1 and 0, respectively, especially for participants in H&Y stages II-IV. In contrast, slope and intercept values were further from 1 and 0, respectively, for the Fast 10Meter Walk Test. Comfortable 10 Meter Walk Test and 6MWT gait speeds appeared to be redundant in people with moderate to severe PD, suggesting the Comfortable 10 Meter Walk Test can be used to estimate 6MWT distance in this population. Copyright © 2016 Elsevier B.V. All rights reserved.

Are the Average Gait Speeds During the 10 Meter and 6 Minute Walk Tests Redundant in Parkinson Disease?

PubMed Central

Duncan, Ryan P.; Combs-Miller, Stephanie A.; McNeely, Marie E.; Leddy, Abigail L.; Cavanaugh, James T.; Dibble, Leland E.; Ellis, Terry D.; Ford, Matthew P.; Foreman, K. Bo; Earhart, Gammon M.

2016-01-01

We investigated the relationships between average gait speed collected with the 10 Meter Walk Test (Comfortable and Fast) and 6 Minute Walk Test (6MWT) in 346 people with Parkinson disease (PD) and how the relationships change with increasing disease severity. Pearson correlation and linear regression analyses determined relationships between 10 Meter Walk Test and 6MWT gait speed values for the entire sample and for sub-samples stratified by Hoehn & Yahr (H&Y) stage I (n=53), II (n=141), III (n=135) and IV (n=17). We hypothesized that redundant tests would be highly and significantly correlated (i.e. r > 0.70, p < 0.05) and would have a linear regression model slope of 1 and intercept of 0. For the entire sample, 6MWT gait speed was significantly (p<0.001) related to the Comfortable 10 Meter Walk Test (r=0.75) and Fast 10 Meter Walk Test (r=0.79) gait speed, with 56% and 62% of the variance in 6MWT gait speed explained, respectively. The regression model of 6MWT gait speed predicted by Comfortable 10 Meter Walk gait speed produced slope and intercept values near 1 and 0, respectively, especially for participants in H&Y stages II–IV. In contrast, slope and intercept values were further from 1 and 0, respectively, for the Fast 10 Meter Walk Test. Comfortable 10 Meter Walk Test and 6MWT gait speeds appeared to be redundant in people with moderate to severe PD, suggesting the Comfortable 10 Meter Walk Test can be used to estimate 6MWT distance in this population. PMID:27915221

Evapotranspiration modelled from stands of three broad-leaved tropical trees in Costa Rica

NASA Astrophysics Data System (ADS)

Bigelow, Seth

2001-10-01

To examine the impact of tree species on the water cycle in a wet tropical region, annual evapotranspiration (ET) was estimated in Costa Rican plantations of three native, broad-leaved tree species that contrasted strongly in leaf size, leaf area and phenology. Evapotranspiration was estimated using the Penman-Monteith equation for transpiration from the dry canopy, the equilibrium equation for evaporation from the understory and a modified Rutter model of interception for evaporation of water from the canopy when wetted by rainfall. Canopy conductance was estimated from stomatal conductance, leaf area and leaf boundary-layer conductance; canopy storage capacity and filling rate were estimated from throughfall measurements. Micrometeorological instruments were mounted on a scaffolding tower.Mean stomatal conductance, which ranged from 0·1 to 0·7 mol m-2 s-1, was similar to boundary-layer conductance, 0·1 to 0·5 mol m-2 s-1, indicating decoupling of stomata from atmospheric conditions. Mean canopy conductance varied from 0·6 to 0·7 mol m-2 s-1 in the 1994 wet season then dropped to 0·3-0·4 mol m-2 s-1 in stands of the two deciduous species, Cordia and Cedrela, as a result of reduced leaf area during the dry season. Despite increased understory evaporation, dry-season ET from these stands was only 78-81% of ET in stands of the evergreen species, Hyeronima. Maximum canopy water depth varied from 0·2 to 2·2 mm, causing modelled interception to vary from 6% to 25% of annual ET. Higher dry-season transpiration rates along with high rates of evaporation of intercepted rainfall in all seasons led to 14% higher annual ET in Hyeronima stands (1509 mm) than in stands of the species with lowest ET,

Shape-preferred orientation (SPO) of oceanic gabbros at IODP Hole 1256D: Implications for magmatic processes

NASA Astrophysics Data System (ADS)

Trela, J.; Ferré, E. C.; Deans, J.; Anma, R.; Morris, A.; Expedition 335 Scientific Party

2012-04-01

Magmatic fabrics in oceanic gabbros close to the sheeted dike-gabbro transition at superfast spreading centers (>200 mm/y) remain poorly investigated. At ~1407 mbsf at IODP Hole 1256D, Expedition 312 recovered non-azimuthally oriented core samples from two gabbro bodies of undetermined shapes: Gabbro 1; 52 m-thick and Gabbro 2; 24 m-thick. Oceanic gabbros in the upper part of the plutonic complex are expected to be macroscopically isotropic, therefore investigating the existence and strength of a fabric requires a highly sensitive method. The Intercept method (Launeau and Robin, 1996), based on quantification of shape-preferred orientation (SPO) in 3-D, has a remarkably high sensitivity for shape anisotropy (0.3%). This method has been used on 33 oceanic gabbro samples from Hole 1256D as a function of depth for each mineral phase. Image analysis using the Intercept method on gabbroic fabrics provides new constraints on crustal accretion mechanisms, the timing of deformation relative to crystallization, i.e., pre-full crystallization fabric vs crystal plastic strain fabric. Observed fabrics provide constrains to test the two-end member ocean accretion models: (A) the "Gabbro Glacier" model; (B) the "Sheeted Sills" model or a hybrid model between (A) and (B). The following lines of evidence are distinct and allow testing of the two models respectively: Model A- The "Gabbro Glacier" model - Microstructures including fractured grains and mechanical twins in plagioclase grains should indicate increasing amounts of strain. SPO is expected to increase as a function of depth. A transitional zone from steeply foliated cumulate gabbros to horizontally layered gabbros is anticipated to occur below the sheeted dike complex. Model B- The "Sheeted Sills" model - No specific correlation between SPO and depth is expected unless geochemical investigations indicate Gabbros 1 and 2 were convecting. Fine-grained margins are expected to occur along the tops and bottoms of the sills. Microstructures should be equilibrated with high angle grain boundaries and should lack syn-magmatic/high-temperature plastic deformation fabrics. If sills are convection-driven then the magmatic foliation may be oblique to compositional layering. SPO image analysis has been performed for major primary silicate phases (plagioclase, orthopyroxene, clinopyroxene, and olivine) and oxides. The Intercept and Ellipsoid softwares have been used to calculate SPO tensors and errors. The results of this research will prove either the "Gabbro Glacier" model or the "Sheeted Sills" model and will provide new quantitative structural data on the mechanisms controlling magmatic accretion at the sheeted dike-plutonic transition zone.

Saccades to future ball location reveal memory-based prediction in a virtual-reality interception task.

PubMed

Diaz, Gabriel; Cooper, Joseph; Rothkopf, Constantin; Hayhoe, Mary

2013-01-16

Despite general agreement that prediction is a central aspect of perception, there is relatively little evidence concerning the basis on which visual predictions are made. Although both saccadic and pursuit eye-movements reveal knowledge of the future position of a moving visual target, in many of these studies targets move along simple trajectories through a fronto-parallel plane. Here, using a naturalistic and racquet-based interception task in a virtual environment, we demonstrate that subjects make accurate predictions of visual target motion, even when targets follow trajectories determined by the complex dynamics of physical interactions and the head and body are unrestrained. Furthermore, we found that, following a change in ball elasticity, subjects were able to accurately adjust their prebounce predictions of the ball's post-bounce trajectory. This suggests that prediction is guided by experience-based models of how information in the visual image will change over time.

Saccades to future ball location reveal memory-based prediction in a virtual-reality interception task

PubMed Central

Diaz, Gabriel; Cooper, Joseph; Rothkopf, Constantin; Hayhoe, Mary

2013-01-01

Despite general agreement that prediction is a central aspect of perception, there is relatively little evidence concerning the basis on which visual predictions are made. Although both saccadic and pursuit eye-movements reveal knowledge of the future position of a moving visual target, in many of these studies targets move along simple trajectories through a fronto-parallel plane. Here, using a naturalistic and racquet-based interception task in a virtual environment, we demonstrate that subjects make accurate predictions of visual target motion, even when targets follow trajectories determined by the complex dynamics of physical interactions and the head and body are unrestrained. Furthermore, we found that, following a change in ball elasticity, subjects were able to accurately adjust their prebounce predictions of the ball's post-bounce trajectory. This suggests that prediction is guided by experience-based models of how information in the visual image will change over time. PMID:23325347

LH Power Losses In Front of the JET Launcher

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

Jacquet, P.; Arnoux, G.; Kirov, K.

2009-11-26

In recent JET experiments, Lower Hybrid (LH) power losses in the Scrape-Off Layer (SOL) were characterized using infra-red (IR) thermography. Hot spots were observed on objects intercepting the field lines passing in front of the LH launcher, i.e. on poloidal limiters and on dumplates located at the top of the tokamak; their locations being in good agreement with magnetic field line tracing using the EFIT equilibrium code. The dumplate temperature was monitored while scanning the launcher position so that the radial distance between field lines intercepting the hot spots and the launcher was increased up to 3.5 cm. The dissipationmore » layer in front of the launcher was estimated to be at least 3.5 cm wide, in agreement with recent measurements on Tore-Supra, but not with simple models that predict a dissipation layer in the mm range.« less

[Dental alveolar bone and dental arch remodeling in children: orthodontic diagnosis and treatments based on individual child arch development].

PubMed

Xiaobing, Li

2016-12-01

The etiology of malocclusions basically involves both congenital and environmental factors. Malocclusion is the result of the abnormal development of the orofacial complex (including tooth, dental alveolar bone, upper and lower jaws). Early orthodontic interceptive treatments involve the elimination of all congenital and environmental factors that contribute to the malformation of the orofacial complex, as well as interrupt the deviated development of the orofacial complex and the occlusion. Early orthodontic interceptive treatments mainly aim to use children's growth potential to correct abnormal developments of occlusions and orthodontically treat malocclusions more efficiently. The early orthodontic interceptive treatments include correcting the child's bad oral habits, training the abnormal functioned para-oral muscles, maintaining the normal eruptions of succeeding permanent teeth, applying interceptive treatments to the mal-developed teeth, and employing functional orthopedic treatments for abnormal growths of the upper and lower jaws. In orthodontics, correcting mal-positioned teeth is called orthodontic treatment, while rectifying the abnormal relationships of the upper and lower jaws is called functional orthopedic treatment. However, no clear definition is available as regards to the early orthodontic interceptive treatment of malocclusions caused by the deviated development of the dental alveolar bone. This new theory of "early dental alveolar bone and dental arch remodeling technique" was proposed by Professor Li Xiaobing of the Department of Pediatric Dentistry, Faculty of Pediatric Dentistry and Orthodontics in West China Hospital of Stomatology through his clinical analyses and investigation of his early orthodontic interceptive treatments. He defined the early orthodontic corrections of abnormal growth of dental alveolar bone as "remodel". The "early dental alveolar bone and dental arch remodeling theory and technique" is proved useful in malocclusion diagnosis and treatment planning during early orthodontic interceptive treatment with malformed dental arch. With the development of the theory and technique, the author intended to prevent and intercept the malocclusion development more effectively and efficiently. This review presents the development and clinical usages of the theory which to provide a new vision in the analysis of malocclusions on the basis of the developmental mechanism of the alveolar bone and dental arch. With clinical case illustration, the author demonstrateshis successful orthodontic clinical practices with this theory, which may contribute to the development of contemporary orthodontic theories and techniques.

Intraoperative centration during small incision lenticule extraction (SMILE)

PubMed Central

Wong, John X.; Wong, Elizabeth P.; Htoon, Hla M.; Mehta, Jodhbir S.

2017-01-01

Abstract To evaluate intraoperative decentration from pupil center and kappa intercept during small incision lenticule extraction (SMILE) and its impact on visual outcomes. This was a retrospective noncomparative case series. A total of 164 eyes that underwent SMILE at the Singapore National Eye Center were included. Screen captures of intraoperative videos were analyzed. Preoperative and 3 month postoperative vision and refractive data were analyzed against decentration. The mean preoperative spherical equivalent (SE) was −5.84 ± 1.77. The mean decentration from the pupil center and from kappa intercept were 0.13 ± 0.06 mm and 0.47mm ± 0.25 mm, respectively. For efficacy and predictability, 69.6% and 95.0% of eyes achieved a visual acuity (VA) of 20/20 and 20/30, respectively, while 83.8% and 97.2% of eyes were within ±0.5D and ±1.0D of the targeted SE. When analyzed across 3 groups of decentration from the pupil center (<0.1 mm, 0.1–0.2 mm, and >0.2 mm), there was no statistically significant association between decentration, safety, efficacy, and predictability. When analyzed across 4 groups of decentration from kappa intercept (<0.2 mm, 0.2–<0.4 mm, 0.4–<0.6 mm, and ≥0.6 mm), there was a trend toward higher efficacy for eyes with decentration of kappa intercept between 0.4 and <0.6 mm (P = .097). A total of 85.4% of eyes in the 0.4 to <0.6 mm group had unaided distance VA of 20/20 or better, as compared to only 57.8% of eyes in ≥0.6 mm group. Decentration of 0.13 mm from the pupil center does not result in compromised visual outcomes. Decentration of greater than 0.6 mm from the kappa intercept may result in compromised visual outcomes. There was a trend toward better efficacy in eyes which had decentered treatment from 0.4 to <0.6 mm from the kappa intercept. Patients with a large kappa intercept (>0.6 mm) should have their lenticule created 0.4 to 0.6 mm from the kappa intercept and not close to the pupil. PMID:28422822

Influence of motivation, self-efficacy and situational factors on the teaching quality of clinical educators.

PubMed

Dybowski, Christoph; Sehner, Susanne; Harendza, Sigrid

2017-05-08

Being exposed to good teachers has been shown to enhance students' knowledge and their clinical performance, but little is known about the underlying psychological mechanisms that provide the basis for being an excellent medical teacher. Self-Determination Theory (SDT) postulates that more self-regulated types of motivation are associated with higher performance. Social Cognitive Theory (SCT) focuses on self-efficacy that has been shown to be positively associated with performance. To investigate the influences of different types of teaching motivation, teaching self-efficacy, and teachers' perceptions of students' skills, competencies and motivation on teaching quality. Before the winter semester 2014, physicians involved in bedside teaching in internal medicine at the University Medical Center Hamburg-Eppendorf completed a questionnaire with sociodemographic items and instruments measuring different dimensions of teaching motivation as well as teaching self-efficacy. During the semester, physicians rated their perceptions of the participating students who rated the teaching quality after each lesson. We performed a random intercept mixed-effects linear regression with students' ratings of teaching quality as the dependent variable and students' general interest in a subject as covariate. We explored potential associations between teachers' dispositions and their perceptions of students' competencies in a mixed-effects random intercept logistic regression. 94 lessons given by 55 teachers with 500 student ratings were analyzed. Neither teaching motivation nor teaching self-efficacy were directly associated with students' rating of teaching quality. Teachers' perceptions of students' competencies and students' general interest in the lesson's subject were positively associated with students' rating of teaching quality. Physicians' perceptions of their students' competencies were significantly positively predicted by their teaching self-efficacy. Teaching quality might profit from teachers who are self-efficacious and able to detect their students' competencies. Students' general interest in a lesson's subject needs to be taken into account when they are asked to evaluate teaching quality.

The Chlamydial Inclusion Preferentially Intercepts Basolaterally Directed Sphingomyelin-Containing Exocytic Vacuoles

PubMed Central

Moore, Elizabeth R.; Fischer, Elizabeth R.; Mead, David J.; Hackstadt, Ted

2010-01-01

Chlamydiae replicate intracellularly within a unique vacuole termed the inclusion. The inclusion circumvents classical endosomal/lysosomal pathways but actively intercepts a subset of Golgi-derived exocytic vesicles containing sphingomyelin (SM) and cholesterol. To further examine this interaction, we developed a polarized epithelial cell model to study vectoral trafficking of lipids and proteins to the inclusion. We examined seven epithelial cell lines for their ability to form single monolayers of polarized cells and support chlamydial development. Of these cell lines, polarized colonic mucosal C2BBe1 cells were readily infected with Chlamydia trachomatis and remained polarized throughout infection. Trafficking of (6-((N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino)hexanoyl)sphingosine) (NBD-C6-ceramide) and its metabolic derivatives, NBD-glucosylceramide (GlcCer) and NBD-SM, was analyzed. SM was retained within L2-infected cells relative to mock-infected cells, correlating with a disruption of basolateral SM trafficking. There was no net retention of GlcCer within L2-infected cells and purification of C. trachomatis elementary bodies from polarized C2BBe1 cells confirmed that bacteria retained only SM. The chlamydial inclusion thus appears to preferentially intercept basolaterally-directed SM-containing exocytic vesicles, suggesting a divergence in SM and GlcCer trafficking. The observed changes in lipid trafficking were a chlamydia-specific effect because Coxiella burnetii-infected cells revealed no changes in GlcCer or SM polarized trafficking. PMID:18778406

Transformations of snow chemistry in the boreal forest: Accumulation and volatilization

USGS Publications Warehouse

Pomeroy, J.W.; Davies, T.D.; Jones, H.G.; Marsh, P.; Peters, N.E.; Tranter, M.

1999-01-01

This paper examines the processes and dynamics of ecologically-important inorganic chemical (primarily NO3-N) accumulation and loss in boreal forest snow during the cold winter period at a northern and southern location in the boreal forest of western Canada. Field observations from Inuvik, Northwest Territories and Waskesiu, Saskatchewan, Canada were used to link chemical transformations and physical processes in boreal forest snow. Data on the disposition and overwinter transformation of snow water equivalent, NO3-, SO42- and other major ions were examined. No evidence of enhanced dry deposition of chemical species to intercepted snow was found at either site except where high atmospheric aerosol concentrations prevailed. At Inuvik, concentrations of SO42- and Cl- were five to six times higher in intercepted snow than in surface snow away from the trees. SO4-S and Cl loads at Inuvik were correspondingly enhanced three-fold within the nearest 0.5 m to individual tree stems. Measurements of snow affected by canopy interception without rapid sublimation provided no evidence of ion volatilization from intercepted snow. Where intercepted snow sublimation rates were significant, ion loads in sub-canopy snow suggested that NO3- volatized with an efficiency of about 62% per snow mass sublimated. Extrapolating this measurement from Waskesiu to sublimation losses observed in other southern boreal environments suggests that 19-25% of snow inputs of NO3- can be lost during intercepted snow sublimation. The amount of N lost during sublimation may be large in high-snowfall, high N load southern boreal forests (Quebec) where 0.42 kg NO3-N ha-1 is estimated as a possible seasonal NO3- volatilization. The sensitivity of the N fluxes to climate and forest canopy variation and implications of the winter N losses for N budgets in the boreal forest are discussed.This paper examines the processes and dynamics of ecologically-important inorganic chemical (primarily NO3-N) accumulation and loss in boreal forest snow during the cold winter period at a northern and southern location in the boreal forest of western Canada. Field observations from Inuvik. Northwest Territories and Waskesiu, Saskatchewan, Canada were used to link chemical transformations and physical processes in boreal forest snow. Data on the disposition and overwinter transformation of snow water equivalent, NO3-, SO42- and other major ions were examined. No evidence of enhanced dry deposition of chemical species to intercepted snow was found at either site except where high atmospheric aerosol concentrations prevailed. At Inuvik, concentrations of SO42- and Cl- were five to six times higher in intercepted snow than in surface snow away from the trees. SO4-S and Cl loads at Inuvik were correspondingly enhanced three-fold within the nearest 0.5 m to individual tree stems. Measurements of snow affected by canopy interception without rapid sublimation provided no evidence of ion volatilization from intercepted snow. Where intercepted snow sublimation rates were significant, ion loads in sub-canopy snow suggested that NO3- volatized with an efficiency of about 62% per snow mass sublimated. Extrapolating this measurement from Waskesiu to sublimation losses observed in other southern boreal environments suggests that 19-25% of snow inputs of NO3- can be lost during intercepted snow sublimation. The amount of N lost during sublimation may be large in high-snowfall, high N load southern boreal forests (Quebec) where 0.42 kg NO3-N ha-1 is estimated as a possible seasonal NO3- volatilization. The sensitivity of the N fluxes to climate and forest canopy variation and implications of the winter N losses for N budgets in the boreal forest are discussed.

A Refined Model for Radar Homing Intercepts.

DTIC Science & Technology

1983-10-27

Helge Toutenburq, Prior Information in Linear Models ,(Wiley, NY, 1982). 7. F. A. Graybill , Introduction to Matrices with Applications in StatisticF... linear target trajectory model z i = 0 + 1 r i + wi () where w i i=I,..., N is a sequence of uncorrelated zero-mean A noise, the general formula for...z i (i=l,..., N) at r. and a linear regression model 1 z i = a0 + a1 r i + w i =(Al) where wi is the corruption noise; the problem is to estimate a0

Ship emissions measurement in the Arctic by plume intercepts of the Canadian Coast Guard icebreaker Amundsen from the Polar 6 aircraft platform

NASA Astrophysics Data System (ADS)

Aliabadi, Amir A.; Thomas, Jennie L.; Herber, Andreas B.; Staebler, Ralf M.; Leaitch, W. Richard; Schulz, Hannes; Law, Kathy S.; Marelle, Louis; Burkart, Julia; Willis, Megan D.; Bozem, Heiko; Hoor, Peter M.; Köllner, Franziska; Schneider, Johannes; Levasseur, Maurice; Abbatt, Jonathan P. D.

2016-06-01

Decreasing sea ice and increasing marine navigability in northern latitudes have changed Arctic ship traffic patterns in recent years and are predicted to increase annual ship traffic in the Arctic in the future. Development of effective regulations to manage environmental impacts of shipping requires an understanding of ship emissions and atmospheric processing in the Arctic environment. As part of the summer 2014 NETCARE (Network on Climate and Aerosols) campaign, the plume dispersion and gas and particle emission factors of effluents originating from the Canadian Coast Guard icebreaker Amundsen operating near Resolute Bay, NU, Canada, were investigated. The Amundsen burned distillate fuel with 1.5 wt % sulfur. Emissions were studied via plume intercepts using the Polar 6 aircraft measurements, an analytical plume dispersion model, and using the FLEXPART-WRF Lagrangian particle dispersion model. The first plume intercept by the research aircraft was carried out on 19 July 2014 during the operation of the Amundsen in the open water. The second and third plume intercepts were carried out on 20 and 21 July 2014 when the Amundsen had reached the ice edge and operated under ice-breaking conditions. Typical of Arctic marine navigation, the engine load was low compared to cruising conditions for all of the plume intercepts. The measured species included mixing ratios of CO2, NOx, CO, SO2, particle number concentration (CN), refractory black carbon (rBC), and cloud condensation nuclei (CCN). The results were compared to similar experimental studies in mid-latitudes. Plume expansion rates (γ) were calculated using the analytical model and found to be γ = 0.75 ± 0.81, 0.93 ± 0.37, and 1.19 ± 0.39 for plumes 1, 2, and 3, respectively. These rates were smaller than prior studies conducted at mid-latitudes, likely due to polar boundary layer dynamics, including reduced turbulent mixing compared to mid-latitudes. All emission factors were in agreement with prior observations at low engine loads in mid-latitudes. Ice-breaking increased the NOx emission factor from EFNOx = 43.1 ± 15.2 to 71.6 ± 9.68 and 71.4 ± 4.14 g kg-diesel-1 for plumes 1, 2, and 3, likely due to changes in combustion temperatures. The CO emission factor was EFCO = 137 ± 120, 12.5 ± 3.70 and 8.13 ± 1.34 g kg-diesel-1 for plumes 1, 2, and 3. The rBC emission factor was EFrBC = 0.202 ± 0.052 and 0.202 ± 0.125 g kg-diesel-1 for plumes 1 and 2. The CN emission factor was reduced while ice-breaking from EFCN = 2.41 ± 0.47 to 0.45 ± 0.082 and 0.507 ± 0.037 × 1016 kg-diesel-1 for plumes 1, 2, and 3. At 0.6 % supersaturation, the CCN emission factor was comparable to observations in mid-latitudes at low engine loads with EFCCN = 3.03 ± 0.933, 1.39 ± 0.319, and 0.650 ± 0.136 × 1014 kg-diesel-1 for plumes 1, 2, and 3.

Modeling the isotopic evolution of snowpack and snowmelt: Testing a spatially distributed parsimonious approach.

PubMed

Ala-Aho, Pertti; Tetzlaff, Doerthe; McNamara, James P; Laudon, Hjalmar; Kormos, Patrick; Soulsby, Chris

2017-07-01

Use of stable water isotopes has become increasingly popular in quantifying water flow paths and travel times in hydrological systems using tracer-aided modeling. In snow-influenced catchments, snowmelt produces a traceable isotopic signal, which differs from original snowfall isotopic composition because of isotopic fractionation in the snowpack. These fractionation processes in snow are relatively well understood, but representing their spatiotemporal variability in tracer-aided studies remains a challenge. We present a novel, parsimonious modeling method to account for the snowpack isotope fractionation and estimate isotope ratios in snowmelt water in a fully spatially distributed manner. Our model introduces two calibration parameters that alone account for the isotopic fractionation caused by sublimation from interception and ground snow storage, and snowmelt fractionation progressively enriching the snowmelt runoff. The isotope routines are linked to a generic process-based snow interception-accumulation-melt model facilitating simulation of spatially distributed snowmelt runoff. We use a synthetic modeling experiment to demonstrate the functionality of the model algorithms in different landscape locations and under different canopy characteristics. We also provide a proof-of-concept model test and successfully reproduce isotopic ratios in snowmelt runoff sampled with snowmelt lysimeters in two long-term experimental catchment with contrasting winter conditions. To our knowledge, the method is the first such tool to allow estimation of the spatially distributed nature of isotopic fractionation in snowpacks and the resulting isotope ratios in snowmelt runoff. The method can thus provide a useful tool for tracer-aided modeling to better understand the integrated nature of flow, mixing, and transport processes in snow-influenced catchments.

An improved approach for measuring the impact of multiple CO2 conductances on the apparent photorespiratory CO2 compensation point through slope-intercept regression

USDA-ARS?s Scientific Manuscript database

Biochemical models of leaf photosynthesis, which are essential for understanding the impact of photosynthesis to changing environments, depend on accurate parameterizations. The CO2 photocompensation point can be especially difficult to determine accurately but can be measured from the intersection ...

Effects of Organizational Characteristics and Human Capital Endowments on Pay of Female and Male Middle School Principals

ERIC Educational Resources Information Center

Young, Phillip; Reimer, Don; Young, Karen Holsey

2010-01-01

Background: Studies addressing pay discrimination for females in education have relied on main effect regression models, mostly examining amount (intercept values) rather than rate of pay (slope coefficients). Purpose: The purpose is to determine if organizational characteristics and human capital endowments purported to influence pay are facially…

Ballistic Missile Intercept from UCAV

DTIC Science & Technology

2011-12-01

aerodynamic forces acting on the ballistic missile , generates a ballistic flight path of the ballistic missile target based on the model developed by...for use against ballistic missile targets) [14] Hutchins, R., ME4703 “ Missile Flight Analysis ” Course Notes, Spring 2005. [15] Stevens, B., and...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited BALLISTIC MISSILE

Physician communication coaching effects on patient experience

PubMed Central

Seiler, Adrianne; Knee, Alexander; Shaaban, Reham; Bryson, Christine; Paadam, Jasmine; Harvey, Rohini; Igarashi, Satoko; LaChance, Christopher; Benjamin, Evan; Lagu, Tara

2017-01-01

Background Excellent communication is a necessary component of high-quality health care. We aimed to determine whether a training module could improve patients’ perceptions of physician communication behaviors, as measured by change over time in domains of patient experience scores related to physician communication. Study design We designed a comprehensive physician-training module focused on improving specific “etiquette-based” physician communication skills through standardized simulations and physician coaching with structured feedback. We employed a quasi-experimental pre-post design, with an intervention group consisting of internal medicine hospitalists and residents and a control group consisting of surgeons. The outcome was percent “always” scores for questions related to patients’ perceptions of physician communication using the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey and a Non-HCAHPS Physician-Specific Patient Experience Survey (NHPPES) administered to patients cared for by hospitalists. Results A total of 128 physicians participated in the simulation. Responses from 5020 patients were analyzed using HCAHPS survey data and 1990 patients using NHPPES survey data. The intercept shift, or the degree of change from pre-intervention percent “always” responses, for the HCAHPS questions of doctors “treating patients with courtesy” “explaining things in a way patients could understand,” and “overall teamwork” showed no significant differences between surgical control and hospitalist intervention patients. Adjusted NHPPES percent excellent survey results increased significantly post-intervention for the questions of specified individual doctors “keeping patient informed” (adjusted intercept shift 9.9% P = 0.019), “overall teamwork” (adjusted intercept shift 11%, P = 0.037), and “using words the patient could understand” (adjusted intercept shift 14.8%, p = 0.001). Conclusion A simulation based physician communication coaching method focused on specific “etiquette-based” communication behaviors through a deliberate practice framework was not associated with significantly improved HCAHPS physician communication patient experience scores. Further research could reveal ways that this model affects patients’ perceptions of physician communication relating to specific physicians or behaviors. PMID:28678872

Physician communication coaching effects on patient experience.

PubMed

Seiler, Adrianne; Knee, Alexander; Shaaban, Reham; Bryson, Christine; Paadam, Jasmine; Harvey, Rohini; Igarashi, Satoko; LaChance, Christopher; Benjamin, Evan; Lagu, Tara

2017-01-01

Excellent communication is a necessary component of high-quality health care. We aimed to determine whether a training module could improve patients' perceptions of physician communication behaviors, as measured by change over time in domains of patient experience scores related to physician communication. We designed a comprehensive physician-training module focused on improving specific "etiquette-based" physician communication skills through standardized simulations and physician coaching with structured feedback. We employed a quasi-experimental pre-post design, with an intervention group consisting of internal medicine hospitalists and residents and a control group consisting of surgeons. The outcome was percent "always" scores for questions related to patients' perceptions of physician communication using the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey and a Non-HCAHPS Physician-Specific Patient Experience Survey (NHPPES) administered to patients cared for by hospitalists. A total of 128 physicians participated in the simulation. Responses from 5020 patients were analyzed using HCAHPS survey data and 1990 patients using NHPPES survey data. The intercept shift, or the degree of change from pre-intervention percent "always" responses, for the HCAHPS questions of doctors "treating patients with courtesy" "explaining things in a way patients could understand," and "overall teamwork" showed no significant differences between surgical control and hospitalist intervention patients. Adjusted NHPPES percent excellent survey results increased significantly post-intervention for the questions of specified individual doctors "keeping patient informed" (adjusted intercept shift 9.9% P = 0.019), "overall teamwork" (adjusted intercept shift 11%, P = 0.037), and "using words the patient could understand" (adjusted intercept shift 14.8%, p = 0.001). A simulation based physician communication coaching method focused on specific "etiquette-based" communication behaviors through a deliberate practice framework was not associated with significantly improved HCAHPS physician communication patient experience scores. Further research could reveal ways that this model affects patients' perceptions of physician communication relating to specific physicians or behaviors.

A study on crown interception with four dominant tree species: a direct measurement

Treesearch

Xiang Li; Jianzhi Niu; Linus Zhang; Qingfu Xiao; Gregory E. McPherson; Natalie van Doorn; Xinxiao Yu; Baoyuan Xie; Salli Dymond; Jiao Li; Chen Meng; Ziteng Luo

2016-01-01

An experiment was conducted to concentrate on the rainfall interception process of individual trees for four common species in Beijing, China, which included needle species (Platycladus orientalis and Pinus tabulaeformis) and broadleaf species (Quercus variabilis and Acer truncatum)....

The dynamics of rainfall interception by a seasonal temperate rainforest.

Treesearch

Timothy E. Link; Mike Unsworth; Danny Marks

2004-01-01

Net canopy interception (Inet) during rainfall in an old-growth Douglas-fir-western hemlock ecosystem was 22.8 and 25.0% of the gross rainfall (PG) for 1999 and 2000, respectively. The average direct throughfall proportion (p) and canopy storage capacity (

How Funding Instability Affects Army Programs

DTIC Science & Technology

2007-01-01

rocket motor, aerodynamic vane controls, and inertial guidance to navigate to an intercept point. Shortly before arrival at the intercept point, the...responsiveness. Significant features of the C-17 include: super-critical wing design and winglets to reduce drag and increase fuel efficiency and

Effects of forest structure on hydrological processes in China

NASA Astrophysics Data System (ADS)

Sun, Jiamei; Yu, Xinxiao; Wang, Henian; Jia, Guodong; Zhao, Yang; Tu, Zhihua; Deng, Wenping; Jia, Jianbo; Chen, Jungang

2018-06-01

There are serious concerns between forest and water quantity, Chinese extensive land area makes the relationship more complicated, thus, the effects of forest structure on hydrological processes in China were not fully comprehended. In this research, forest's hydrological functions, including rainfall partitioning, litter interception, evapotranspiration (ET), were analyzed in China. The results showed that throughfall was the largest proportion of gross precipitation with fraction between 69.3 ± 8.8% and 84.4 ± 5.6%. Then was canopy interception which varied from 14.6 ± 1.4% to 29.1 ± 3.3%. Throughfall was correlated with gross precipitation, canopy thickness and canopy density. Canopy interception was correlated with gross precipitation, LAI, canopy density, biomass, mixed degree, uniform angle index, aggregation index. Stemflow accounted for only 1.2 ± 0.32% of gross precipitation, with the greatest fraction of 2.1 ± 0.2% in XBH site and the least fraction of 0.3 ± 0.1% in DB site. Gross precipitation was the main factor in determining stemflow. DB site had the greatest litter interception (7.7 ± 0.8 mm) and HB site had the least (0.9 ± 0.3 mm). Litter interception had closer correlation with undecomposed litter mass (0.66) than total litter mass (0.46). Path-coefficient analysis showed that stand density, Shannon-Wiener index, litter mass, size ratio had greater impact on litter interception than other factors. ET was mainly influenced by precipitation, and it also correlated with LAI, canopy density and biomass. In north China, ET percentage (the ratio of ET and precipitation) was 82.7-109.5%, while it decreased to 63.1-88.5% in south China, ET demand in XBS site was larger than precipitation. ET percentage increased with increasing latitude and elevation, decreased with increasing temperature.

Corner store purchases made by adults, adolescents and children: items, nutritional characteristics and amount spent.

PubMed

Lent, Michelle R; Vander Veur, Stephanie; Mallya, Giridhar; McCoy, Tara A; Sanders, Timothy A; Colby, Lisa; Rauchut Tewksbury, Colleen; Lawman, Hannah G; Sandoval, Brianna; Sherman, Sandy; Wylie-Rosett, Judith; Foster, Gary D

2015-06-01

Corner stores, also known as bodegas, are prevalent in low-income urban areas and primarily stock high-energy foods and beverages. Little is known about individual-level purchases in these locations. The purpose of the present study was to assess corner store purchases (items, nutritional characteristics and amount spent) made by children, adolescents and adults in a low-income urban environment. Evaluation staff used 9238 intercept surveys to directly examine food and beverage purchases. Intercepts were collected at 192 corner stores in Philadelphia, PA, USA. Participants were adult, adolescent and child corner store shoppers. Among the 9238 intercept surveys, there were 20 244 items. On average, at each corner store visit, consumers purchased 2.2 (sd 2.1) items (1.3 (sd 2.0) foods and 0.9 (sd 0.9) beverages) that cost $US 2.74 (sd $US 3.52) and contained 2786.5 (sd 4454.2) kJ (666.0 (sd 1064.6) kcal). Whether the data were examined as a percentage of total items purchased or as a percentage of intercepts, the most common corner store purchases were beverages, chips, prepared food items, pastries and candy. Beverage purchases occurred during 65.9% of intercepts and accounted for 39.2% of all items. Regular soda was the most popular beverage purchase. Corner store purchases averaged 66.2 g of sugar, 921.1 mg of sodium and 2.5 g of fibre per intercept. Compared with children and adolescents, adults spent the most money and purchased the most energy. Urban corner store shoppers spent almost $US 3.00 for over 2700 kJ (650 kcal) per store visit. Obesity prevention efforts may benefit from including interventions aimed at changing corner store food environments in low-income, urban areas.

Evolving Concepts on Adjusting Human Resting Energy Expenditure Measurements for Body Size

PubMed Central

Heymsfield, Steven B.; Thomas, Diana; Bosy-Westphal, Anja; Shen, Wei; Peterson, Courtney M.; Müller, Manfred J.

2012-01-01

Establishing if an adult’s resting energy expenditure (REE) is high or low for their body size is a pervasive question in nutrition research. Early workers applied body mass and height as size measures and formulated the Surface Law and Kleiber’s Law, although each has limitations when adjusting REE. Body composition methods introduced during the mid-twentieth century provided a new opportunity to identify metabolically homogeneous “active” compartments. These compartments all show improved correlations with REE estimates over body mass-height approaches, but collectively share a common limitation: REE-body composition ratios are not “constant” but vary across men and women and with race, age, and body size. The now-accepted alternative to ratio-based norms is to adjust for predictors by applying regression models to calculate “residuals” that establish if a REE is relatively high or low. The distinguishing feature of statistical REE-body composition models is a “non-zero” intercept of unknown origin. The recent introduction of imaging methods has allowed development of physiological tissue-organ based REE prediction models. Herein we apply these imaging methods to provide a mechanistic explanation, supported by experimental data, for the non-zero intercept phenomenon and in that context propose future research directions for establishing between subject differences in relative energy metabolism. PMID:22863371

Modeling indoor particulate exposures in inner city school classrooms

PubMed Central

Gaffin, Jonathan M.; Petty, Carter R.; Hauptman, Marissa; Kang, Choong-Min; Wolfson, Jack M.; Awad, Yara Abu; Di, Qian; Lai, Peggy S.; Sheehan, William J.; Baxi, Sachin; Coull, Brent A.; Schwartz, Joel D.; Gold, Diane R.; Koutrakis, Petros; Phipatanakul, Wanda

2016-01-01

Outdoor air pollution penetrates buildings and contributes to total indoor exposures. We investigated the relationship of indoor to outdoor particulate matter in inner-city school classrooms. The School Inner City Asthma Study investigates the effect of classroom-based environmental exposures on students with asthma in the northeast United States. Mixed-effects linear models were used to determine the relationships between indoor PM2.5 and BC and their corresponding outdoor concentrations, and to develop a model for predicting exposures to these pollutants. The indoor-outdoor sulfur ratio was used as an infiltration factor of outdoor fine particles. Weeklong concentrations of PM2.5 and BC in 199 samples from 136 classrooms (30 school buildings) were compared to those measured at a central monitoring site averaged over the same timeframe. Mixed effects regression models found significant random intercept and slope effects, which indicate that: 1) there are important PM2.5 sources in classrooms; 2) the penetration of outdoor PM2.5 particles varies by school, and 3) the site-specific outside PM2.5 levels (inferred by the models) differ from those observed at the central monitor site. Similar results were found for BC except for lack of indoor sources. The fitted predictions from the sulfur-adjusted models were moderately predictive of observed indoor pollutant levels (Out of sample correlations: PM2.5: r2 = 0.68, BC; r2 = 0.61). Our results suggest that PM2.5 has important classroom sources, which vary by school. Furthermore, using these mixed effects models, classroom exposures can be accurately predicted for dates when central site measures are available but indoor measures are not available. PMID:27599884

Developing and validating risk prediction models in an individual participant data meta-analysis

PubMed Central

2014-01-01

Background Risk prediction models estimate the risk of developing future outcomes for individuals based on one or more underlying characteristics (predictors). We review how researchers develop and validate risk prediction models within an individual participant data (IPD) meta-analysis, in order to assess the feasibility and conduct of the approach. Methods A qualitative review of the aims, methodology, and reporting in 15 articles that developed a risk prediction model using IPD from multiple studies. Results The IPD approach offers many opportunities but methodological challenges exist, including: unavailability of requested IPD, missing patient data and predictors, and between-study heterogeneity in methods of measurement, outcome definitions and predictor effects. Most articles develop their model using IPD from all available studies and perform only an internal validation (on the same set of data). Ten of the 15 articles did not allow for any study differences in baseline risk (intercepts), potentially limiting their model’s applicability and performance in some populations. Only two articles used external validation (on different data), including a novel method which develops the model on all but one of the IPD studies, tests performance in the excluded study, and repeats by rotating the omitted study. Conclusions An IPD meta-analysis offers unique opportunities for risk prediction research. Researchers can make more of this by allowing separate model intercept terms for each study (population) to improve generalisability, and by using ‘internal-external cross-validation’ to simultaneously develop and validate their model. Methodological challenges can be reduced by prospectively planned collaborations that share IPD for risk prediction. PMID:24397587

Health Insurance: The Trade-Off Between Risk Pooling and Moral Hazard.

DTIC Science & Technology

1989-12-01

bias comes about because we suppress the intercept term in estimating VFor the power, the test is against 1, - 1. With this transform, the risk...dealing with the same utility function. As one test of whether families behave in the way economic theory suggests, we have also fitted a probit model of...nonparametric alternative to test our results’ sensitivity to the assumption of a normal error in both the theoretical and empirical models of the

Dissolution Rate, Weathering Mechanics, and Friability of TNT, Comp B, Tritonal, and Octol

DTIC Science & Technology

2010-02-01

second conceptual model also simulates dissolution of a particle that experiences constant soil moisture such as one mixed in with the soil...or are mediated by moisture on the particle surface is not yet known. The identities of these red products are also unknown as are their health...it using the outdoor data. The model assumes that raindrops intercepted by HE particles were fully saturated in HE as they dripped off. Particle

Radiative transfer in shrub savanna sites in Niger: Preliminary results from HAPEX-Sahel. Part 1: Modelling surface reflectance using a geometric-optical approach

NASA Technical Reports Server (NTRS)

Franklin, Janet; Duncan, Jeff; Huete, Alfredo R.; vanLeeuwen, W. J. D.; Li, Xiaowen; Begue, Agnes

1994-01-01

To use optical remote sensing to monitor land surface-climate interactions over large areas, algorithms must be developed to relate multispectral measurements to key variables controlling the exchange of matter (water, carbon dioxide) and energy between the land surface and the atmosphere. The proportion of the ground covered by vegetation and the interception of photosynthetically active radiation (PAR) by vegetation are examples of two variables related to evapotranspiration and primary production, respectively. An areal-proportion model of the multispectral reflectance of shrub savanna, composed of scattered shrubs with a grass, forb or soil understory, predicted the reflectance of two 0.5 km(exp 2) sites as the area-weighted average of the shrub and understory or 'background' reflectances. Although the shaded crown and shaded background have darker reflectances, ignoring them in the area-weighted model is not serious when shrub cover is low and solar zenith angle is small. A submodel predicted the reflectance of the shrub crown as a function of the foliage reflectance and amount of plant material within the crown, and the background reflectance scattered or transmitted through canopy gaps (referred to as a soil-plant 'spectral interaction' term). One may be able to combine these two models to estimate both the fraction of vegetation cover and interception of PAR by green vegetation in a shrub savanna.

Deviation from symmetrically self-similar branching in trees predicts altered hydraulics, mechanics, light interception and metabolic scaling.

PubMed

Smith, Duncan D; Sperry, John S; Enquist, Brian J; Savage, Van M; McCulloh, Katherine A; Bentley, Lisa P

2014-01-01

The West, Brown, Enquist (WBE) model derives symmetrically self-similar branching to predict metabolic scaling from hydraulic conductance, K, (a metabolism proxy) and tree mass (or volume, V). The original prediction was Kα V(0.75). We ask whether trees differ from WBE symmetry and if it matters for plant function and scaling. We measure tree branching and model how architecture influences K, V, mechanical stability, light interception and metabolic scaling. We quantified branching architecture by measuring the path fraction, Pf : mean/maximum trunk-to-twig pathlength. WBE symmetry produces the maximum, Pf = 1.0. We explored tree morphospace using a probability-based numerical model constrained only by biomechanical principles. Real tree Pf ranged from 0.930 (nearly symmetric) to 0.357 (very asymmetric). At each modeled tree size, a reduction in Pf led to: increased K; decreased V; increased mechanical stability; and decreased light absorption. When Pf was ontogenetically constant, strong asymmetry only slightly steepened metabolic scaling. The Pf ontogeny of real trees, however, was 'U' shaped, resulting in size-dependent metabolic scaling that exceeded 0.75 in small trees before falling below 0.65. Architectural diversity appears to matter considerably for whole-tree hydraulics, mechanics, photosynthesis and potentially metabolic scaling. Optimal architectures likely exist that maximize carbon gain per structural investment. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Evaluation of gene expression classification studies: factors associated with classification performance.

PubMed

Novianti, Putri W; Roes, Kit C B; Eijkemans, Marinus J C

2014-01-01

Classification methods used in microarray studies for gene expression are diverse in the way they deal with the underlying complexity of the data, as well as in the technique used to build the classification model. The MAQC II study on cancer classification problems has found that performance was affected by factors such as the classification algorithm, cross validation method, number of genes, and gene selection method. In this paper, we study the hypothesis that the disease under study significantly determines which method is optimal, and that additionally sample size, class imbalance, type of medical question (diagnostic, prognostic or treatment response), and microarray platform are potentially influential. A systematic literature review was used to extract the information from 48 published articles on non-cancer microarray classification studies. The impact of the various factors on the reported classification accuracy was analyzed through random-intercept logistic regression. The type of medical question and method of cross validation dominated the explained variation in accuracy among studies, followed by disease category and microarray platform. In total, 42% of the between study variation was explained by all the study specific and problem specific factors that we studied together.

The modifying influence of country development on the effect of individual educational attainment on self-rated health.

PubMed

van der Kooi, Anne L F; Stronks, Karien; Thompson, Caroline A; DerSarkissian, Maral; Arah, Onyebuchi A

2013-11-01

We investigated how much the Human Development Index (HDI), a global measure of development, modifies the effect of education on self-reported health. We analyzed cross-sectional World Health Survey data on 217,642 individuals from 49 countries, collected in 2002 to 2005, with random-intercept multilevel linear regression models. We observed greater positive associations between educational levels and self-reported good health with increasing HDI. The magnitude of this effect modification of the education-health relation tended to increase with educational attainment. For example, before adjustment for effect modification, at comparable HDI, on average, finishing primary school was associated with better general health (b = 1.49; 95% confidence interval [CI] = 1.18, 1.80). With adjustment for effect modification by HDI, the impact became 4.63 (95% CI = 3.63, 5.62) for every 0.1 increase in HDI. Among those who completed high school, these associations were, respectively, 5.59 (95% CI = 5.20, 5.98) and 9.95 (95% CI = 8.89, 11.00). The health benefits of educational attainment are greater in countries with greater human development. Health inequalities attributable to education are, therefore, larger in more developed countries.

Travel time to maternity care and its effect on utilization in rural Ghana: a multilevel analysis.

PubMed

Masters, Samuel H; Burstein, Roy; Amofah, George; Abaogye, Patrick; Kumar, Santosh; Hanlon, Michael

2013-09-01

Rates of neonatal and maternal mortality are high in Ghana. In-facility delivery and other maternal services could reduce this burden, yet utilization rates of key maternal services are relatively low, especially in rural areas. We tested a theoretical implication that travel time negatively affects the use of in-facility delivery and other maternal services. Empirically, we used geospatial techniques to estimate travel times between populations and health facilities. To account for uncertainty in Ghana Demographic and Health Survey cluster locations, we adopted a novel approach of treating the location selection as an imputation problem. We estimated a multilevel random-intercept logistic regression model. For rural households, we found that travel time had a significant effect on the likelihood of in-facility delivery and antenatal care visits, holding constant education, wealth, maternal age, facility capacity, female autonomy, and the season of birth. In contrast, a facility's capacity to provide sophisticated maternity care had no detectable effect on utilization. As the Ghanaian health network expands, our results suggest that increasing the availability of basic obstetric services and improving transport infrastructure may be important interventions. Copyright © 2013 Elsevier Ltd. All rights reserved.

How to Identify Success Among Networks That Promote Active Living

PubMed Central

Varda, Danielle; Reed, Hannah; Retrum, Jessica; Tabak, Rachel; Gustat, Jeanette; O'Hara Tompkins, Nancy

2015-01-01

Objectives. We evaluated organization- and network-level factors that influence organizations’ perceived success. This is important for managing interorganizational networks, which can mobilize communities to address complex health issues such as physical activity, and for achieving change. Methods. In 2011, we used structured interview and network survey data from 22 states in the United States to estimate multilevel random-intercept models to understand organization- and network-level factors that explain perceived network success. Results. A total of 53 of 59 “whole networks” met the criteria for inclusion in the analysis (89.8%). Coordinators identified 559 organizations, with 3 to 12 organizations from each network taking the online survey (response rate = 69.7%; range = 33%–100%). Occupying a leadership position (P < .01), the amount of time with the network (P < .05), and support from community leaders (P < .05) emerged as correlates of perceived success. Conclusions. Organizations’ perceptions of success can influence decisions about continuing involvement and investment in networks designed to promote environment and policy change for active living. Understanding these factors can help leaders manage complex networks that involve diverse memberships, varied interests, and competing community-level priorities. PMID:26378863