Sample records for passive gene-environment correlation

  1. Missing heritability, polygenic scores, and gene–environment correlation

    PubMed Central

    Plomin, Robert

    2013-01-01

    This special issue amply fulfils its aim of moving the study of gene × environment (GE) interplay forward constructively and creatively, exploiting contributions from diverse disciplines. Rather than discussing the many interesting findings and methods in this special issue, I will comment on two cross-cutting issues – one about genes and the other about the environment – that came to mind as I read these articles. PMID:24007418

  2. Gene-Environment Correlation Underlying the Association between Parental Negativity and Adolescent Externalizing Problems

    ERIC Educational Resources Information Center

    Marceau, Kristine; Horwitz, Briana N.; Narusyte, Jurgita; Ganiban, Jody M.; Spotts, Erica L.; Reiss, David; Neiderhiser, Jenae M.

    2013-01-01

    Studies of adolescent or parent-based twins suggest that gene-environment correlation (rGE) is an important mechanism underlying parent-adolescent relationships. However, information on how parents' and children's genes and environments influence correlated parent "and" child behaviors is needed to distinguish types of rGE. The…

  3. Latent variable models for gene-environment interactions in longitudinal studies with multiple correlated exposures.

    PubMed

    Tao, Yebin; Sánchez, Brisa N; Mukherjee, Bhramar

    2015-03-30

    Many existing cohort studies designed to investigate health effects of environmental exposures also collect data on genetic markers. The Early Life Exposures in Mexico to Environmental Toxicants project, for instance, has been genotyping single nucleotide polymorphisms on candidate genes involved in mental and nutrient metabolism and also in potentially shared metabolic pathways with the environmental exposures. Given the longitudinal nature of these cohort studies, rich exposure and outcome data are available to address novel questions regarding gene-environment interaction (G × E). Latent variable (LV) models have been effectively used for dimension reduction, helping with multiple testing and multicollinearity issues in the presence of correlated multivariate exposures and outcomes. In this paper, we first propose a modeling strategy, based on LV models, to examine the association between repeated outcome measures (e.g., child weight) and a set of correlated exposure biomarkers (e.g., prenatal lead exposure). We then construct novel tests for G × E effects within the LV framework to examine effect modification of outcome-exposure association by genetic factors (e.g., the hemochromatosis gene). We consider two scenarios: one allowing dependence of the LV models on genes and the other assuming independence between the LV models and genes. We combine the two sets of estimates by shrinkage estimation to trade off bias and efficiency in a data-adaptive way. Using simulations, we evaluate the properties of the shrinkage estimates, and in particular, we demonstrate the need for this data-adaptive shrinkage given repeated outcome measures, exposure measures possibly repeated and time-varying gene-environment association. PMID:25545894

  4. Gene–environment interdependence

    Microsoft Academic Search

    Michael Rutter

    2012-01-01

    The modern understanding of genetic influences, of environmental effects, of mental disorder, and of heritabilities is noted. The practical utility of finding susceptibility genes with a very small effect is questioned. The empirical findings and implications of developmental perturbations, epigenetics, gene–environment correlations and interactions are then discussed. It is noted that the genes involved in gene–environment interactions may be concerned

  5. Observed positive parenting behaviors and youth genotype: Evidence for gene–environment correlations and moderation by parent personality traits

    PubMed Central

    OPPENHEIMER, CAROLINE W.; HANKIN, BENJAMIN L.; JENNESS, JESSICA L.; YOUNG, JAMI F.; SMOLEN, ANDREW

    2013-01-01

    Gene–environment correlations (rGE) have been demonstrated in behavioral genetic studies, but rGE have proven elusive in molecular genetic research. Significant gene–environment correlations may be difficult to detect because potential moderators could reduce correlations between measured genetic variants and the environment. Molecular genetic studies investigating moderated rGE are lacking. This study examined associations between child catechol-O-methyltransferase genotype and aspects of positive parenting (responsiveness and warmth), and whether these associations were moderated by parental personality traits (neuroticism and extraversion) among a general community sample of third, sixth, and ninth graders (N = 263) and their parents. Results showed that parent personality traits moderated the rGE association between youths’ genotype and coded observations of positive parenting. Parents with low levels of neuroticism and high levels of extraversion exhibited greater sensitive responsiveness and warmth, respectively, to youth with the valine/valine genotype. Moreover, youth with this genotype exhibited lower levels of observed anger. There was no association between the catechol-O-methyltransferase genotype and parenting behaviors for parents high on neuroticism and low on extraversion. Findings highlight the importance of considering moderating variables that may influence child genetic effects on the rearing environment. Implications for developmental models of maladaptive and adaptive child outcomes, and interventions for psychopathology, are discussed within a developmental psychopathology framework. PMID:23398761

  6. A latent variable approach to study gene-environment interactions in the presence of multiple correlated exposures.

    PubMed

    Sánchez, Brisa N; Kang, Shan; Mukherjee, Bhramar

    2012-06-01

    Many existing cohort studies initially designed to investigate disease risk as a function of environmental exposures have collected genomic data in recent years with the objective of testing for gene-environment interaction (G × E) effects. In environmental epidemiology, interest in G × E arises primarily after a significant effect of the environmental exposure has been documented. Cohort studies often collect rich exposure data; as a result, assessing G × E effects in the presence of multiple exposure markers further increases the burden of multiple testing, an issue already present in both genetic and environment health studies. Latent variable (LV) models have been used in environmental epidemiology to reduce dimensionality of the exposure data, gain power by reducing multiplicity issues via condensing exposure data, and avoid collinearity problems due to presence of multiple correlated exposures. We extend the LV framework to characterize gene-environment interaction in presence of multiple correlated exposures and genotype categories. Further, similar to what has been done in case-control G × E studies, we use the assumption of gene-environment (G-E) independence to boost the power of tests for interaction. The consequences of making this assumption, or the issue of how to explicitly model G-E association has not been previously investigated in LV models. We postulate a hierarchy of assumptions about the LV model regarding the different forms of G-E dependence and show that making such assumptions may influence inferential results on the G, E, and G × E parameters. We implement a class of shrinkage estimators to data adaptively trade-off between the most restrictive to most flexible form of G-E dependence assumption and note that such class of compromise estimators can serve as a benchmark of model adequacy in LV models. We demonstrate the methods with an example from the Early Life Exposures in Mexico City to Neuro-Toxicants Study of lead exposure, iron metabolism genes, and birth weight. PMID:21955029

  7. A latent variable approach to study gene-environment interactions in the presence of multiple correlated exposures

    PubMed Central

    Kang, Shan; Mukherjee, Bhramar

    2015-01-01

    Summary Many existing cohort studies initially designed to investigate disease risk as a function of environmental exposures have collected genomic data in recent years with the objective of testing for gene-environment interaction (G × E) effects. In environmental epidemiology, interest in G × E arises primarily after a significant effect of the environmental exposure has been documented. Cohort studies often collect rich exposure data, as a result, assessing G × E effects in the presence of multiple exposure markers further increases the burden of multiple testing, an issue already present in both genetic and environment health studies. Latent variable (LV) models have been used in environmental epidemiology to reduce dimensionality of the exposure data, gain power by reducing multiplicity issues via condensing exposure data, and avoid collinearity problems due to presence of multiple correlated exposures. We extend the LV framework to characterize gene-environment interaction in presence of multiple correlated exposures and genotype categories. Further, similar to what has been done in case-control G × E studies, we use the assumption of gene-environment (G-E) independence to boost the power of tests for interaction. The consequences of making this assumption, or the issue of how to explicitly model G-E association has not been previously investigated in LV models. We postulate a hierarchy of assumptions about the LV model regarding the different forms of G-E dependence and show that making such assumptions may influence inferential results on the G, E, and G × E parameters. We implement a class of shrinkage estimators to data adaptively trade-off between the most restrictive to most flexible form of G-E dependence assumption and note that such class of compromise estimators can serve as a benchmark of model adequacy in LV models. We demonstrate the methods with an example from the Early Life Exposures in Mexico City to Neuro-Toxicants (ELEMENT) study of lead exposure, iron metabolism genes, and birth weight. PMID:21955029

  8. Evocative gene–environment correlation in the mother–child relationship: A twin study of interpersonal processes

    PubMed Central

    KLAHR, ASHLEA M.; THOMAS, KATHERINE M.; HOPWOOD, CHRISTOPHER J.; KLUMP, KELLY L.; BURT, S. ALEXANDRA

    2014-01-01

    The behavior genetic literature suggests that genetically influenced characteristics of the child elicit specific behaviors from the parent. However, little is known about the processes by which genetically influenced child characteristics evoke parental responses. Interpersonal theory provides a useful framework for identifying reciprocal behavioral processes between children and mothers. The theory posits that, at any given moment, interpersonal behavior varies along the orthogonal dimensions of warmth and control and that the interpersonal behavior of one individual tends to elicit corresponding or contrasting behavior from the other (i.e., warmth elicits warmth, whereas control elicits submission). The current study thus examined these dimensions of interpersonal behavior as they relate to the parent–child relationship in 546 twin families. A computer joystick was used to rate videos of mother–child interactions in real time, yielding information on mother and child levels of warmth and control throughout the interaction. Analyses indicated that maternal control, but not maternal warmth, was influenced by evocative gene–environment correlational processes, such that genetic influences on maternal control and child control were largely overlapping. Moreover, these common genetic influences were present both cross-sectionally and over the course of the interaction. Such findings not only confirm the presence of evocative gene–environment correlational processes in the mother–child relationship but also illuminate at least one of the specific interpersonal behaviors that underlie this evocative process. PMID:23398756

  9. Child-evoked maternal negativity from 9 to 27 months: Evidence of gene-environment correlation and its moderation by marital distress.

    PubMed

    Fearon, R M Pasco; Reiss, David; Leve, Leslie D; Shaw, Daniel S; Scaramella, Laura V; Ganiban, Jody M; Neiderhiser, Jenae M

    2014-09-12

    Past research has documented pervasive genetic influences on emotional and behavioral disturbance across the life span and on liability to adult psychiatric disorder. Increasingly, interest is turning to mechanisms of gene-environment interplay in attempting to understand the earliest manifestations of genetic risk. We report findings from a prospective adoption study, which aimed to test the role of evocative gene-environment correlation in early development. Included in the study were 561 infants adopted at birth and studied between 9 and 27 months, along with their adoptive parents and birth mothers. Birth mother psychiatric diagnoses and symptoms scales were used as indicators of genetic influence, and multiple self-report measures were used to index adoptive mother parental negativity. We hypothesized that birth mother psychopathology would be associated with greater adoptive parent negativity and that such evocative effects would be amplified under conditions of high adoptive family adversity. The findings suggested that genetic factors associated with birth mother externalizing psychopathology may evoke negative reactions in adoptive mothers in the first year of life, but only when the adoptive family environment is characterized by marital problems. Maternal negativity mediated the effects of genetic risk on child adjustment at 27 months. The results underscore the importance of genetically influenced evocative processes in early development. PMID:25216383

  10. Gene-environment dependence creates spurious gene-environment interaction.

    PubMed

    Dudbridge, Frank; Fletcher, Olivia

    2014-09-01

    Gene-environment interactions have the potential to shed light on biological processes leading to disease and to improve the accuracy of epidemiological risk models. However, relatively few such interactions have yet been confirmed. In part this is because genetic markers such as tag SNPs are usually studied, rather than the causal variants themselves. Previous work has shown that this leads to substantial loss of power and increased sample size when gene and environment are independent. However, dependence between gene and environment can arise in several ways including mediation, pleiotropy, and confounding, and several examples of gene-environment interaction under gene-environment dependence have recently been published. Here we show that under gene-environment dependence, a statistical interaction can be present between a marker and environment even if there is no interaction between the causal variant and the environment. We give simple conditions under which there is no marker-environment interaction and note that they do not hold in general when there is gene-environment dependence. Furthermore, the gene-environment dependence applies to the causal variant and cannot be assessed from marker data. Gene-gene interactions are susceptible to the same problem if two causal variants are in linkage disequilibrium. In addition to existing concerns about mechanistic interpretations, we suggest further caution in reporting interactions for genetic markers. PMID:25152454

  11. Genes, Environment, and Human Behavior.

    ERIC Educational Resources Information Center

    Bloom, Mark V.; Cutter, Mary Ann; Davidson, Ronald; Dougherty, Michael J.; Drexler, Edward; Gelernter, Joel; McCullough, Laurence B.; McInerney, Joseph D.; Murray, Jeffrey C.; Vogler, George P.; Zola, John

    This curriculum module explores genes, environment, and human behavior. This book provides materials to teach about the nature and methods of studying human behavior, raise some of the ethical and public policy dilemmas emerging from the Human Genome Project, and provide professional development for teachers. An extensive Teacher Background…

  12. PASSIVE SENSOR IMAGING USING CROSS CORRELATIONS OF NOISY SIGNALS IN A SCATTERING MEDIUM

    E-print Network

    Garnier, Josselin

    PASSIVE SENSOR IMAGING USING CROSS CORRELATIONS OF NOISY SIGNALS IN A SCATTERING MEDIUM JOSSELIN's function between two passive sensors can be estimated from the cross correlation of recorded signal that the travel time can be effectively estimated when the ray joining the two sensors continues into the noise

  13. Gene-Environment Interplay, Family Relationships, and Child Adjustment

    ERIC Educational Resources Information Center

    Horwitz, Briana N.; Neiderhiser, Jenae M.

    2011-01-01

    This paper reviews behavioral genetic research from the past decade that has moved beyond simply studying the independent influences of genes and environments. The studies considered in this review have instead focused on understanding gene-environment interplay, including genotype-environment correlation (rGE) and genotype x environment…

  14. Gene-Environment Interplay between Number of Friends and Prosocial Leadership Behavior in Children

    ERIC Educational Resources Information Center

    Rivizzigno, Alessandra S.; Brendgen, Mara; Feng, Bei; Vitaro, Frank; Dionne, Ginette; Tremblay, Richard E.; Boivin, Michel

    2014-01-01

    Enriched environments may moderate the effect of genetic factors on prosocial leadership (gene-environment interaction, G × E). However, positive environmental experiences may also themselves be influenced by a genetic disposition for prosocial leadership (gene-environment correlation, rGE). Relating these processes to friendships, the present…

  15. Gene-Environment Interplay between Peer Rejection and Depressive Behavior in Children

    ERIC Educational Resources Information Center

    Brendgen, Mara; Vitaro, Frank; Boivin, Michel; Girard, Alain; Bukowski, William M.; Dionne, Ginette; Tremblay, Richard E.; Perusse, Daniel

    2009-01-01

    Background: Genetic risk for depressive behavior may increase the likelihood of exposure to environmental stressors (gene-environment correlation, rGE). By the same token, exposure to environmental stressors may moderate the effect of genes on depressive behavior (gene-environment interaction, GxE). Relating these processes to a peer-related…

  16. Statistics for Testing Gene–Environment Interaction

    Microsoft Academic Search

    Momiao Xiong; Xuesen Wu

    \\u000a This chapter introduces a number of new gene–environment interaction measures and develop novel statistics that are based\\u000a on these new gene–environment interaction measures. These new statistics are simple, less computationally intensive and easy\\u000a to implement. It is hoped that these developments may open a new avenue for large-scale genome-wide gene–environment interaction\\u000a analysis, deciphering the genetic and physiological meaning of gene–environment

  17. Genes, Environments, and Behavior 1

    NSDL National Science Digital Library

    American Association for the Advancement of Science (; )

    2006-04-25

    Genes, Environment, and Behavior 1 is the first of two lessons about the field called behavioral genetics, in which scientists study the reciprocating influences of genes and environments on behavior, particularly human behavior. It provides students with a clear understanding of how behavior is defined by scientists and an overview of the genetic and environmental forces that interact to shape behavior.In this lesson, students are assigned reading materials from the book Behavioral Genetics: An introduction to how genes and environments interact through development to shape differences in mood, personality, and intelligence, published by AAAS and The Hastings Center. These chapters are character-based and have relatively easy context. Provided are quizzes that that are administered after the short readings. These quizzes foster a discussion on each topic in behavior and genetics. The titles of the chapters in this lesson are: 1) "What is behavioral genetics?", 2) "How do genes work within their environments?", 3) "How do environments impinge upon the genes?"

  18. Gene-environment interactions in mental disorders

    PubMed Central

    Tsuang, Ming T; Bar, Jessica L; Stone, William S; Faraone, Stephen V

    2004-01-01

    Research clearly shows that both nature and nurture play important roles in the genesis of psychopathology. In this paper, we focus on 'gene-environment interaction' in mental disorders, using genetic control of sensitivity to the environment as our definition of that term. We begin with an examination of methodological issues involving gene-environment interactions, with examples concerning psychiatric and neurological conditions. Then we review the interactions in psychiatric disorders using twin, adoption and association designs. Finally, we consider gene-environment interactions in selected neurodevelopmental disorders (autism and schizophrenia). PMID:16633461

  19. Gene-Environment Studies and Borderline Personality Disorder: A Review

    PubMed Central

    Carpenter, Ryan W.; Tomko, Rachel L.; Boomsma, Dorret I.

    2014-01-01

    We review recent gene-environment studies relevant to borderline personality disorder, including those focusing on impulsivity, emotion sensitivity, suicidal behavior, aggression and anger, and the borderline personality phenotype itself. Almost all the studies reviewed suffered from a number of methodological and statistical problems, limiting the conclusions that currently can be drawn. The best evidence to date supports a gene-environment correlation (rGE) model for borderline personality traits and a range of adverse life events, indicating that those at risk for BPD are also at increased risk for exposure to environments that may trigger BPD. We provide suggestions regarding future research on GxE interaction and rGE effects in borderline personality. PMID:23250817

  20. Spatial dependence of passive scalar correlation functions in

    E-print Network

    Fominov, Yakov

    solution Chaotic flow in curved pipe linear velocity profile at scales . Entropy (Kramer) function S. O^,N^ -- orthogonal matrices 0, 321321 =++>> Incompressibility of flow minimum at tii = 321 eee >>>> #12;Results, 3D-case Pair correlation function (S)aa2,a1,);( 222 2 2 R

  1. Gene-Environment Interplay Between Cannabis and Psychosis

    PubMed Central

    Henquet, Cécile; Di Forti, Marta; Morrison, Paul; Kuepper, Rebecca; Murray, Robin M.

    2008-01-01

    Cannabis use is considered a contributory cause of schizophrenia and psychotic illness. However, only a small proportion of cannabis users develop psychosis. This can partly be explained by the amount and duration of the consumption of cannabis and by its strength but also by the age at which individuals are first exposed to cannabis. Genetic factors, in particular, are likely to play a role in the short- and the long-term effects cannabis may have on psychosis outcome. This review will therefore consider the interplay between genes and exposure to cannabis in the development of psychotic symptoms and schizophrenia. Studies using genetic, epidemiological, experimental, and observational techniques will be discussed to investigate gene-environment correlation gene-environment interaction, and higher order interactions within the cannabis-psychosis association. Evidence suggests that mechanisms of gene-environment interaction are likely to underlie the association between cannabis and psychosis. In this respect, multiple variations within multiple genes—rather than single genetic polymorphisms—together with other environmental factors (eg, stress) may interact with cannabis to increase the risk of psychosis. Further research on these higher order interactions is needed to better understand the biological pathway by which cannabis use, in some individuals, may cause psychosis in the short- and long term. PMID:18723841

  2. Simulation of GPR Passive Interferometry using Cross-correlation for LNAPL Model Monitoring Application

    NASA Astrophysics Data System (ADS)

    Li, J.; Zeng, Z.; Liu, F.

    2013-12-01

    Passive interferometry is based on the relation between the reflection and the transmission responses of the subsurface. The transmission response can be received at surface in the presence of the non-artificial source in the subsurface. The reflection response can be obtained by the cross-correlation or Multi-dimensional deconvolution (MDD) of the transmission response. In this paper, we investigate the basic principles of synthesizing the virtual shot gathers record from the transmission response and design a finite-difference algorithm for the simulation of long-duration GPR measurements in the presence of passive source randomly spaced in the subsurface. The random noise sources have the characteristic including random duration time, random waveform and random position distribution. Here we apply the GPR passive interferometry in light non-aqueous phase liquid (LNAPL) model monitoring and use the cross-correlation method to retrieve the target signal. With the simulation result, we can accurately obtain the dielectric constant, EM velocity, dynamic monitoring change characteristics and other information of LNAPL model by common midpoint (CMP) velocity analysis and normal moveout correction (NMO) method. The result demonstrates that the passive GPR interferometry is feasible in subsurface LNAPL and other target monitoring. It provides an idea and foundation for real passive interferometry GPR application.

  3. Simulation of GPR Passive Interferometry using Cross-correlation for LNAPL Model Monitoring Application

    NASA Astrophysics Data System (ADS)

    Li, J.; Zeng, Z.; Liu, F.

    2011-12-01

    Passive interferometry is based on the relation between the reflection and the transmission responses of the subsurface. The transmission response can be received at surface in the presence of the non-artificial source in the subsurface. The reflection response can be obtained by the cross-correlation or Multi-dimensional deconvolution (MDD) of the transmission response. In this paper, we investigate the basic principles of synthesizing the virtual shot gathers record from the transmission response and design a finite-difference algorithm for the simulation of long-duration GPR measurements in the presence of passive source randomly spaced in the subsurface. The random noise sources have the characteristic including random duration time, random waveform and random position distribution. Here we apply the GPR passive interferometry in light non-aqueous phase liquid (LNAPL) model monitoring and use the cross-correlation method to retrieve the target signal. With the simulation result, we can accurately obtain the dielectric constant, EM velocity, dynamic monitoring change characteristics and other information of LNAPL model by common midpoint (CMP) velocity analysis and normal moveout correction (NMO) method. The result demonstrates that the passive GPR interferometry is feasible in subsurface LNAPL and other target monitoring. It provides an idea and foundation for real passive interferometry GPR application.

  4. Biological Implications of Gene-Environment Interaction

    ERIC Educational Resources Information Center

    Rutter, Michael

    2008-01-01

    Gene-environment interaction (G x E) has been treated as both a statistical phenomenon and a biological reality. It is argued that, although there are important statistical issues that need to be considered, the focus has to be on the biological implications of G x E. Four reports of G x E deriving from the Dunedin longitudinal study are used as…

  5. Gene-Environment Research and Cancer Epidemiology

    Cancer.gov

    Risk of most cancer types are determined by a complex interplay of genetic and environmental factors. Recent studies provide theoretical and empirical evidence that additional genetic and environmental factors can be identified in studies that examine gene-environment (GxE) interactions. More importantly, GxE interaction research has the potential to facilitate insights into biological mechanisms and strategies for cancer prevention and control. Despite progress, several challenges remain for performing these studies.

  6. Gene-Environment Interplay in the Link of Friends' and Nonfriends' Behaviors with Children's Social Reticence in a Competitive Situation

    ERIC Educational Resources Information Center

    Guimond, Fanny-Alexandra; Brendgen, Mara; Vitaro, Frank; Forget-Dubois, Nadine; Dionne, Ginette; Tremblay, Richard E.; Boivin, Michel

    2014-01-01

    This study used a genetically informed design to assess the effects of friends' and nonfriends' reticent and dominant behaviors on children's observed social reticence in a competitive situation. Potential gene-environment correlations (rGE) and gene-environment interactions (GxE) in the link between (a) friends' and…

  7. Gene–environment interactions in psychiatry: joining forces with neuroscience

    Microsoft Academic Search

    Avshalom Caspi; Terrie E. Moffitt

    2006-01-01

    Gene–environment interaction research in psychiatry is new, and is a natural ally of neuroscience. Mental disorders have known environmental causes, but there is heterogeneity in the response to each causal factor, which gene–environment findings attribute to genetic differences at the DNA sequence level. Such findings come from epidemiology, an ideal branch of science for showing that gene–environment interactions exist in

  8. The Role of Individual Correlates and Class Norms in Defending and Passive Bystanding Behavior in Bullying: A Multilevel Analysis

    ERIC Educational Resources Information Center

    Pozzoli, Tiziana; Gini, Gianluca; Vieno, Alessio

    2012-01-01

    This study investigates possible individual and class correlates of defending and passive bystanding behavior in bullying, in a sample of 1,825 Italian primary school (mean age = 10 years 1 month) and middle school (mean age = 13 years 2 months) students. The findings of a series of multilevel regression models show that both individual (e.g.,…

  9. Comparison of eye-safe solid state laser DIAL with passive gas filter correlation measurements from aircraft and spacecraft

    NASA Technical Reports Server (NTRS)

    Hess, Robert V.; Staton, Leo D.; Wallio, H. Andrew; Wang, Liang-Guo

    1992-01-01

    Differential Absorption Lidar (DIAL) using solid state Ti:sapphire lasers finds current application in the NASA/LASE Project for H2O vapor measurements in the approximately = 0.820 micron region for the lower and mid-troposphere and in potential future applications in planned measurements of the approximately = 0.940 micron region where both strong and weak absorption lines enables measurements throughout the troposphere and lower stratosphere. The challenge exists to perform measurements in the eye-safe greater than 1.5 micron region. A comparison between DIAL and passive Gas Filter Correlation Radiometer (GFCR) measurements is made. The essence of the differences in signal to noise ratio for DIAL and passive GFCR measurements is examined. The state of the art of lasers and optical parametric oscillators (OPO's) is discussed.

  10. Correlation between Abortion and Infertility among Nonsmoking Women with a History of Passive Smoking in Childhood and Adolescence

    PubMed Central

    Amirkhani, Jila; Yadollah-Damavandi, Soheila; Mirlohi, Seyed Mohammad-Javad; Nasiri, Seyede Mahnaz; Parsa, Yekta

    2014-01-01

    The aim of this study is to evaluate the correlation of exposing to the cigarette smoke in childhood and adolescence with infertility and abortion in women. This case-control study evaluated 178 women who had been attended to at the Amir-al-Momenin Hospital in Tehran in 2012-2013. Seventy-eight women with chief complaint of abortion, infertility, and missed abortion and 100 healthy women were considered as case and control groups, respectively. The tool was a questionnaire with two parts. In the first part demographic information was gathered and in the second part the information regarding the history of passive smoking in childhood and adolescence period, abortion, and infertility was gathered. The mean age in case and control groups was 26.24 ± 3.1 and 27.3 ± 4.2 years, respectively. The mean body mass index (BMI) was 25.74 ± 1.38?Kg/m2. Abortion rates among passive smoker and nonpassive smoker patients were statistically significant (P = 0.036). Based on findings of this study, the experience of being a passive smoker in childhood and adolescence in women will increase the risk of abortion and infertility in the future, which could be the reason to encourage the society to step back from smoking cigarettes. PMID:25763404

  11. Multispectral passive microwave correlations with an antecedent precipitation index using the Nimbus 7 SMMR 

    E-print Network

    Wilke, Gregory Delfin

    1984-01-01

    s on T ra n s f o rms Comparison of Transforms and Multiple Linear Regression . Comparison of Case Study Grid Cells Supporting Data CHAPTER V. SUMMARY AND CONCLUSIONS Summary Conclusions Recommendations for Further Research. REFERENCES 55 56 59... the soil moisture content by measuring the brightness temperature and estimating the soil surface temperature from meteorological observations. Neneely (1977) attempted to show this by using 1. 55 cm passive microwave data from the Nimbus 5 sensor...

  12. Passive advection of a vector field: Anisotropy, finite correlation time, exact solution and logarithmic corrections to ordinary scaling

    E-print Network

    N. V. Antonov; N. M. Gulitskiy

    2015-06-18

    In this work we study the generalization of the problem, considered in [{\\it Phys. Rev. E} {\\bf 91}, 013002 (2015)], to the case of {\\it finite} correlation time of the environment (velocity) field. The model describes a vector (e.g., magnetic) field, passively advected by a strongly anisotropic turbulent flow. Inertial-range asymptotic behavior is studied by means of the field theoretic renormalization group and the operator product expansion. The advecting velocity field is Gaussian, with finite correlation time and preassigned pair correlation function. Due to the presence of distinguished direction ${\\bf n}$, all the multiloop diagrams in this model are vanish, so that the results obtained are exact. The inertial-range behavior of the model is described by two regimes (the limits of vanishing or infinite correlation time) that correspond to the two nontrivial fixed points of the RG equations. Their stability depends on the relation between the exponents in the energy spectrum ${\\cal E} \\propto k_{\\bot}^{1-\\xi}$ and the dispersion law $\\omega \\propto k_{\\bot}^{2-\\eta}$. In contrast to the well known isotropic Kraichnan's model, where various correlation functions exhibit anomalous scaling behavior with infinite sets of anomalous exponents, here the corrections to ordinary scaling are polynomials of logarithms of the integral turbulence scale $L$.

  13. Gene-Environment Contributions to Young Adult Sexual Partnering

    Microsoft Academic Search

    Carolyn T. Halpern; Christine E. Kaestle; Guang Guo; Denise D. Hallfors

    2007-01-01

    To date, there has been relatively little work on gene-environment contributions to human sexuality, especially molecular\\u000a analyses examining the potential contributions of specific polymorphisms in conjunction with life experiences. Using Wave\\u000a III data from 717 heterozygous young adult sibling pairs included in the National Longitudinal Study of Adolescent Health,\\u000a this article examined the combined contributions of attendance at religious services

  14. Optical reflectometry based on correlation detection and its application to the in-service monitoring of WDM passive optical network.

    PubMed

    Takushima, Y; Chung, Y C

    2007-04-30

    We propose and demonstrate a novel technique for measuring the distribution of the reflectivity along an optical fiber transmission line. Unlike the conventional optical time-domain reflectometer (OTDR), the proposed technique utilizes the data-modulated transmitter itself instead of the optical short-pulse source, and monitors the distribution of the back-reflected light by calculating the cross-correlation of the transmitted and back-reflected signals. In this paper, we describe the operating principle of the proposed technique and discuss its potential limitation on the dynamic range. We also show that this limitation can be mitigated by using the discrete-component elimination algorithm. In addition, we experimentally demonstrate that the proposed technique can be used for the in-service monitoring of the transmission fibers in a wavelength-division multiplexed passive optical network (WDM PON). PMID:19532785

  15. Gene–Environment Interactions in Severe Mental Illness

    PubMed Central

    Uher, Rudolf

    2014-01-01

    Severe mental illness (SMI) is a broad category that includes schizophrenia, bipolar disorder, and severe depression. Both genetic disposition and environmental exposures play important roles in the development of SMI. Multiple lines of evidence suggest that the roles of genetic and environmental factors depend on each other. Gene–environment interactions may underlie the paradox of strong environmental factors for highly heritable disorders, the low estimates of shared environmental influences in twin studies of SMI, and the heritability gap between twin and molecular heritability estimates. Sons and daughters of parents with SMI are more vulnerable to the effects of prenatal and postnatal environmental exposures, suggesting that the expression of genetic liability depends on environment. In the last decade, gene–environment interactions involving specific molecular variants in candidate genes have been identified. Replicated findings include an interaction between a polymorphism in the AKT1 gene and cannabis use in the development of psychosis and an interaction between the length polymorphism of the serotonin transporter gene and childhood maltreatment in the development of persistent depressive disorder. Bipolar disorder has been underinvestigated, with only a single study showing an interaction between a functional polymorphism in the BDNF gene and stressful life events triggering bipolar depressive episodes. The first systematic search for gene–environment interactions has found that a polymorphism in CTNNA3 may sensitize the developing brain to the pathogenic effect of cytomegalovirus in utero, leading to schizophrenia in adulthood. Strategies for genome-wide investigations will likely include coordination between epidemiological and genetic research efforts, systematic assessment of multiple environmental factors in large samples, and prioritization of genetic variants. PMID:24860514

  16. A Penalized Robust Method for Identifying Gene-Environment Interactions

    PubMed Central

    Shi, Xingjie; Liu, Jin; Huang, Jian; Zhou, Yong; Xie, Yang; Ma, Shuangge

    2015-01-01

    In high-throughput studies, an important objective is to identify gene-environment interactions associated with disease outcomes and phenotypes. Many commonly adopted methods assume specific parametric or semiparametric models, which may be subject to model mis-specification. In addition, they usually use significance level as the criterion for selecting important interactions. In this study, we adopt the rank-based estimation, which is much less sensitive to model specification than some of the existing methods and includes several commonly encountered data and models as special cases. Penalization is adopted for the identification of gene-environment interactions. It achieves simultaneous estimation and identification and does not rely on significance level. For computation feasibility, a smoothed rank estimation is further proposed. Simulation shows that under certain scenarios, for example with contaminated or heavy-tailed data, the proposed method can significantly outperform the existing alternatives with more accurate identification. We analyze a lung cancer prognosis study with gene expression measurements under the AFT (accelerated failure time) model. The proposed method identifies interactions different from those using the alternatives. Some of the identified genes have important implications. PMID:24616063

  17. Gene-Environment Interactions in Asthma: Genetic and Epigenetic Effects

    PubMed Central

    Lee, Jong-Uk; Kim, Jeong Dong

    2015-01-01

    Over the past three decades, a large number of genetic studies have been aimed at finding genetic variants associated with the risk of asthma, applying various genetic and genomic approaches including linkage analysis, candidate gene polymorphism studies, and genome-wide association studies (GWAS). However, contrary to general expectation, even single nucleotide polymorphisms (SNPs) discovered by GWAS failed to fully explain the heritability of asthma. Thus, application of rare allele polymorphisms in well defined phenotypes and clarification of environmental factors have been suggested to overcome the problem of 'missing' heritability. Such factors include allergens, cigarette smoke, air pollutants, and infectious agents during pre- and post-natal periods. The first and simplest interaction between a gene and the environment is a candidate interaction of both a well known gene and environmental factor in a direct physical or chemical interaction such as between CD14 and endotoxin or between HLA and allergens. Several GWAS have found environmental interactions with occupational asthma, aspirin exacerbated respiratory disease, tobacco smoke-related airway dysfunction, and farm-related atopic diseases. As one of the mechanisms behind gene-environment interaction is epigenetics, a few studies on DNA CpG methylation have been reported on subphenotypes of asthma, pitching the exciting idea that it may be possible to intervene at the junction between the genome and the environment. Epigenetic studies are starting to include data from clinical samples, which will make them another powerful tool for research on gene-environment interactions in asthma. PMID:26069107

  18. Determining 252Cf source strength by absolute passive neutron correlation counting

    NASA Astrophysics Data System (ADS)

    Croft, S.; Henzlova, D.

    2013-06-01

    Physically small, lightly encapsulated, radionuclide sources containing 252Cf are widely used for a vast variety of industrial, medical, educational and research applications requiring a convenient source of neutrons. For many quantitative applications, such as detector efficiency calibrations, the absolute strength of the neutron emission is needed. In this work we show how, by using a neutron multiplicity counter the neutron emission rate can be obtained with high accuracy. This provides an independent and alternative way to create reference sources in-house for laboratories such as ours engaged in international safeguards metrology. The method makes use of the unique and well known properties of the 252Cf spontaneous fission system and applies advanced neutron correlation counting methods. We lay out the foundation of the method and demonstrate it experimentally. We show that accuracy comparable to the best methods currently used by national bodies to certify neutron source strengths is possible.

  19. Gene-environment interaction in posttraumatic stress disorder: an update.

    PubMed

    Koenen, Karestan C; Amstadter, Ananda B; Nugent, Nicole R

    2009-10-01

    The authors provide a detailed review of the extant gene-environment interaction (GxE) research in the etiology of posttraumatic stress disorder (PTSD). They begin with a discussion of why PTSD is uniquely fitting for the innovative framework of GxE methodology, followed by a review of the heritability and main effect molecular genetics studies of PTSD. Next, they discuss the six GxE investigations to date on PTSD. They end with a discussion of future directions and significance of this research, with an emphasis on the expansion of psychosocial factors that may be fitting environmental variables for inclusion in this new research area. The authors posit that GxE research is vital to elucidating risk and resilience following exposure to a potentially traumatic event. PMID:19743189

  20. Gene-environment Interaction in Posttraumatic Stress Disorder: An Update

    PubMed Central

    Koenen, Karestan C.; Amstadter, Ananda B.; Nugent, Nicole R.

    2009-01-01

    This article provides a detailed review of the extant gene-environment interaction (GxE) research in the etiology of posttraumatic stress disorder (PTSD). We begin by a discussion of why PTSD is uniquely fitting for the innovative framework of GxE methodology, followed by a review of the heritability and main effect molecular genetics studies of PTSD. Next, we discuss the six GxE investigations to date on PTSD. We end with a discussion of future directions and significance of this research, with an emphasis on the expansion of psychosocial factors that may be fitting ‘E’ variables for inclusion in this new research area. We posit that GxE research is vital to elucidating risk and resilience following exposure to a potentially traumatic event. PMID:19743189

  1. Risk, Resilience, and Gene-Environment Interplay in Primates

    PubMed Central

    Suomi, Stephen J.

    2011-01-01

    Objectives: The primary objectives of the body of research reported here was to demonstrate significant interactions between genetic and social environmental factors that clearly influenced both the biological and behavioral responses of rhesus monkeys to social stressors such as separation from familial and/or familiar conspecifics throughout development and to investigate possible mechanisms underlying such interactions. Methods: Prospective longitudinal studies of rhesus monkeys reared in both captive and naturalistic settings have examined individual differences in biological and behavioral responses to stress throughout the lifespan. Results: Approximately 20% of monkeys in both settings consistently display unusually fearful and anxious-like behavioral reactions to novel, mildly stressful social situations and depressive-like symptoms following repeated separations from familial and/or familiar conspecifics during their infant and juvenile years, as well as profound and prolonged activation of the hypothalamic-pituitary-adrenal (HPA) axis in both situations. Both genetic and experiential factors – as well as their interaction -- are implicated in these reactions to social stress. For example, a specific polymorphism in the serotonin transporter gene is associated with deficits in neonatal neurobehavioral functioning and in extreme behavioral and adreno-cortical responses to social separation among infant and juvenile monkeys who experienced insecure early attachments but not in monkeys who developed secure attachment relationships with their mothers during infancy (maternal “buffering”). Similar instances of maternal “buffering” have been demonstrated in significant gene-environment interplay involving several other “candidate” gene polymorphisms. Moreover, because the attachment style of a monkey mother is typically “copied” by her daughters when they become mothers themselves, similar “buffering” is likely to occur for the next generation of infants carrying so-called “risk” alleles. Conclusions: Specific gene-environment interactions can influence behavioral and biological reactions to social stress not only throughout development but also across successive generations of rhesus monkey families. PMID:22114610

  2. MAOA genotype, social exclusion and aggression: an experimental test of a gene-environment interaction.

    PubMed

    Gallardo-Pujol, D; Andrés-Pueyo, A; Maydeu-Olivares, A

    2013-02-01

    In 2002, Caspi and colleagues provided the first epidemiological evidence that genotype may moderate individuals' responses to environmental determinants. However, in a correlational study great care must be taken to ensure the proper estimation of the causal relationship. Here, a randomized experiment was performed to test the hypothesis that the MAOA gene promoter polymorphism (MAOA-LPR) interacts with environmental adversity in determining aggressive behavior using laboratory analogs of real-life conditions. A sample of 57 Caucasian male students of Catalan and Spanish origin was recruited at the University of Barcelona. Ostracism, or social exclusion, was induced as environmental adversity using the Cyberball software. Laboratory aggression was assessed with the Point Subtraction Aggression Paradigm (PSAP), which was used as an analog of antisocial behavior. We also measured aggressiveness by means of the reduced version of the Aggression Questionnaire. The MAOA-LPR polymorphism showed a significant effect on the number of aggressive responses in the PSAP (F(1,53) = 4.63, P = 0.03, partial ?(2) = 0.08), as well as social exclusion (F(1,53) = 8.03, P = 0.01, partial ?(2) = 0.13). Most notably, however, we found that the MAOA-LPR polymorphism interacts significantly with social exclusion in order to provoke aggressive behavior (F(1,53) = 4.42, P = 0.04, partial ?(2) = 0.08), remarkably, the low-activity allele of the MAOA-LPR polymorphism carriers in the ostracized group show significantly higher aggression scores than the rest. Our results support the notion that gene-environment interactions can be successfully reproduced within a laboratory using analogs and an appropriate design. We provide guidelines to test gene-environment interactions hypotheses under controlled, experimental settings. PMID:23067570

  3. Candidate gene-environment interaction research: reflections and recommendations.

    PubMed

    Dick, Danielle M; Agrawal, Arpana; Keller, Matthew C; Adkins, Amy; Aliev, Fazil; Monroe, Scott; Hewitt, John K; Kendler, Kenneth S; Sher, Kenneth J

    2015-01-01

    Studying how genetic predispositions come together with environmental factors to contribute to complex behavioral outcomes has great potential for advancing the understanding of the development of psychopathology. It represents a clear theoretical advance over studying these factors in isolation. However, research at the intersection of multiple fields creates many challenges. We review several reasons why the rapidly expanding candidate gene-environment interaction (cG×E) literature should be considered with a degree of caution. We discuss lessons learned about candidate gene main effects from the evolving genetics literature and how these inform the study of cG×E. We review the importance of the measurement of the gene and environment of interest in cG×E studies. We discuss statistical concerns with modeling cG×E that are frequently overlooked. Furthermore, we review other challenges that have likely contributed to the cG×E literature being difficult to interpret, including low power and publication bias. Many of these issues are similar to other concerns about research integrity (e.g., high false-positive rates) that have received increasing attention in the social sciences. We provide recommendations for rigorous research practices for cG×E studies that we believe will advance its potential to contribute more robustly to the understanding of complex behavioral phenotypes. PMID:25620996

  4. CD14 tobacco gene-environment interaction in atopic children.

    PubMed

    Hussein, Yousri M; Shalaby, Sally M; Zidan, Haidy E; Sabbah, Norhan A; Karam, Nehad A; Alzahrani, Saad S

    2013-01-01

    Studying gene-environment interactions may elucidate the complex origins of atopic diseases. The aim of this study was to evaluate the association of CD14 polymorphisms and atopy in Egyptian children and to study whether atopy is influenced by CD14 interaction with tobacco smoke exposure. CD14 -159 C/T and CD14 -550 C/T were genotyped in 500 asthmaic children, 150 allergic rhinitis children and 150 controls. We found that CD14 -159T allele, CD14 -550T allele and CD14 -159T/-550T haplotype were significantly associated with atopic asthma and allergic rhinitis groups. CD14 -159 TT and CD14 -550 TT genotypes associated with elevated IgE levels in children exposed to tobacco smoke. The TT genotype of CD14 -159 C/T and CD14 -550 C/T was associated with higher serum levels of sCD14. The present study indicated that CD14 gene polymorphisms may contribute to susceptibility to atopy in Egyptian children and influenced with tobacco smoke exposure. PMID:24044964

  5. Sleep Duration and Depressive Symptoms: A Gene-Environment Interaction

    PubMed Central

    Watson, Nathaniel F.; Harden, Kathryn Paige; Buchwald, Dedra; Vitiello, Michael V.; Pack, Allan I.; Strachan, Eric; Goldberg, Jack

    2014-01-01

    Objective: We used quantitative genetic models to assess whether sleep duration modifies genetic and environmental influences on depressive symptoms. Method: Participants were 1,788 adult twins from 894 same-sex twin pairs (192 male and 412 female monozygotic [MZ] pairs, and 81 male and 209 female dizygotic [DZ] pairs] from the University of Washington Twin Registry. Participants self-reported habitual sleep duration and depressive symptoms. Data were analyzed using quantitative genetic interaction models, which allowed the magnitude of additive genetic, shared environmental, and non-shared environmental influences on depressive symptoms to vary with sleep duration. Results: Within MZ twin pairs, the twin who reported longer sleep duration reported fewer depressive symptoms (ec = -0.17, SE = 0.06, P < 0.05). There was a significant gene × sleep duration interaction effect on depressive symptoms (a'c = 0.23, SE = 0.08, P < 0.05), with the interaction occurring on genetic influences that are common to both sleep duration and depressive symptoms. Among individuals with sleep duration within the normal range (7-8.9 h/night), the total heritability (h2) of depressive symptoms was approximately 27%. However, among individuals with sleep duration within the low (< 7 h/night) or high (? 9 h/night) range, increased genetic influence on depressive symptoms was observed, particularly at sleep duration extremes (5 h/night: h2 = 53%; 10 h/night: h2 = 49%). Conclusion: Genetic contributions to depressive symptoms increase at both short and long sleep durations. Citation: Watson NF; Harden KP; Buchwald D; Vitiello MV; Pack AI; Stachan E; Goldberg J. Sleep duration and depressive symptoms: a gene-environment interaction. SLEEP 2014;37(2):351-358. PMID:24497663

  6. Gene-Environment interactions in addictive disorders: epidemiological and methodological aspects.

    E-print Network

    Paris-Sud XI, Université de

    Gene-Environment interactions in addictive disorders: epidemiological and methodological aspects. Interactions gène - environnement dans les pathologies addictives: aspects méthodologiques et épidémiologiques associated to addictive behaviors. Twin studies first help to disentangle the respective role of environment

  7. A survey on OR and mathematical methods applied on gene-environment networks

    Microsoft Academic Search

    Gerhard-Wilhelm Weber; Erik Kropat; Basak Akteke-Öztürk; Zafer-Korcan Görgülü

    2009-01-01

    In this paper, we survey the recent advances and mathematical foundations of gene-environment networks. We explain their interdisciplinary\\u000a implications with special regard to human and life sciences as well as financial sciences. Special attention is paid to applications\\u000a in Operational Research and environmental protection. Originally developed in the context of modeling and prediction of gene-expression\\u000a patterns, gene-environment networks have proved

  8. The Impact of Gene–Environment Interaction on Alcohol Use Disorders

    PubMed Central

    Dick, Danielle M.; Kendler, Kenneth S.

    2012-01-01

    This article describes three types of gene–environment interactions and the challenges inherent in interpreting these interactions. It also reports on what is known about gene–environment interactions in the field of alcohol use disorders (AUDs). Twin studies of the interaction of genetic and environmental influences on AUDs have resulted in relatively consistent findings and have suggested general mechanisms for interaction effects. These studies generally find that environments that exert more social control (e.g., higher parental monitoring, less migratory neighborhoods, etc.) tend to reduce genetic influences, whereas other environments allow greater opportunity to express genetic predispositions, such as those characterized by more deviant peers and greater alcohol availability. Conversely, the gene–environment literature that has been developed surrounding specific genes has focused largely on the role of stress as a moderator of genetic effects. PMID:23134047

  9. Exploiting Gene Expression Variation to Capture Gene-Environment Interactions for Disease

    PubMed Central

    Idaghdour, Youssef; Awadalla, Philip

    2013-01-01

    Gene-environment interactions have long been recognized as a fundamental concept in evolutionary, quantitative, and medical genetics. In the genomics era, study of how environment and genome interact to shape gene expression variation is relevant to understanding the genetic architecture of complex phenotypes. While genetic analysis of gene expression variation focused on main effects, little is known about the extent of interaction effects implicating regulatory variants and their consequences on transcriptional variation. Here we survey the current state of the concept of transcriptional gene-environment interactions and discuss its utility for mapping disease phenotypes in light of the insights gained from genome-wide association studies of gene expression. PMID:23755064

  10. Can Clouds Dance? Neural Correlates of Passive Conceptual Expansion Using a Metaphor Processing Task: Implications for Creative Cognition

    ERIC Educational Resources Information Center

    Rutter, Barbara; Kroger, Soren; Stark, Rudolf; Schweckendiek, Jan; Windmann, Sabine; Hermann, Christiane; Abraham, Anna

    2012-01-01

    Creativity has emerged in the focus of neurocognitive research in the past decade. However, a heterogeneous pattern of brain areas has been implicated as underpinning the neural correlates of creativity. One explanation for these divergent findings lies in the fact that creativity is not usually investigated in terms of its many underlying…

  11. Gene-Environment Interactions in Genome-Wide Association Studies: Current Approaches and New Directions

    ERIC Educational Resources Information Center

    Winham, Stacey J.; Biernacka, Joanna M.

    2013-01-01

    Background: Complex psychiatric traits have long been thought to be the result of a combination of genetic and environmental factors, and gene-environment interactions are thought to play a crucial role in behavioral phenotypes and the susceptibility and progression of psychiatric disorders. Candidate gene studies to investigate hypothesized…

  12. Confirmatory and Competitive Evaluation of Alternative Gene-Environment Interaction Hypotheses

    ERIC Educational Resources Information Center

    Belsky, Jay; Pluess, Michael; Widaman, Keith F.

    2013-01-01

    Background: Most gene-environment interaction (GXE) research, though based on clear, vulnerability-oriented hypotheses, is carried out using exploratory rather than hypothesis-informed statistical tests, limiting power and making formal evaluation of competing GXE propositions difficult. Method: We present and illustrate a new regression technique…

  13. How Gene-Environment Interaction Affects Children's Anxious and Fearful Behavior. Science Briefs

    ERIC Educational Resources Information Center

    National Scientific Council on the Developing Child, 2007

    2007-01-01

    "Science Briefs" summarize the findings and implications of a recent study in basic science or clinical research. This brief reports on the study "Evidence for a Gene-Environment Interaction in Predicting Behavioral Inhibition in Middle Childhood" (N. A. Fox, K E. Nichols, H. A. Henderson, K. Rubin, L. Schmidt, D. Hamer, M. Ernst, and D. S.…

  14. BOGENVI: A Biomedical Ontology for Modelling Gene*Environment Interactions on Intermediate Phenotypes in Nutrigenomics Research

    Microsoft Academic Search

    Antonio Fabregat; Elisabet Barrera; María Arregui; Olga Portolés; Dolores Corella; Óscar Coltell

    2008-01-01

    Nutritional Genomics is demanding computing models and technological platforms in order to support acquisition, storage, management and presentation of all the information generated coming from heterogeneous sources: genotypes, environmental factors (diet and other life-style factors) and phenotypes (intermediate and final phenotypes). Our aim is to build a biomedical ontology in order to modelling gene*environment interactions on intermediate phenotypes by means

  15. From 'omics' to complex disease: a systems biology approach to gene-environment interactions in cancer

    Microsoft Academic Search

    Sarah S. Knox

    2010-01-01

    BACKGROUND: Cancer is a complex disease that involves a sequence of gene-environment interactions in a progressive process that cannot occur without dysfunction in multiple systems, including DNA repair, apoptotic and immune functions. Epigenetic mechanisms, responding to numerous internal and external cues in a dynamic ongoing exchange, play a key role in mediating environmental influences on gene expression and tumor development.

  16. J Epidemiol Community Health . Author manuscript Candidate gene-environment interactions

    E-print Network

    Paris-Sud XI, Université de

    to environmental tobacco smoke is related to early onset asthma, testing whether ETS exposure and 17q variant had interactive effects on early onset asthma was testing a candidate gene-environment interaction, even though ( ). Alterations in DNA methylation may partly be due to environmental factors ( ). Instances to10 11 test

  17. Gene-Gene, Gene-Environment & Multiple Interactions in Colorectal Cancer

    Microsoft Academic Search

    FARID E. AHMED

    2006-01-01

    This review comprehensively evaluates the influence of gene-gene, gene-environment and multiple interactions on the risk of colorectal cancer (CRC). Methods of studying these interactions and their limitations have been discussed herein. There is a need to develop biomarkers of exposure and of risk that are sensitive, specific, present in the pathway of the disease, and that have been clinically tested

  18. Mathematical and Data Mining Contributions to Dynamics and Optimization of Gene-Environment Networks

    Microsoft Academic Search

    Gerhard-Wilhelm Weber; Pakize Taylan; Basak Akteke

    This paper further introduces continuous optimization into the fields of computa- tional biology and environmental protection which belong to the most challenging and emerging areas of science. It refines earlier ones of our models on gene-environment patterns by the use of optimization theory. We emphasize that it bases on and presents work done in (61, 66). Furthermore, our paper tries

  19. Testing for Sufficient-Cause Gene-Environment Interactions Under the Assumptions of Independence and Hardy-Weinberg Equilibrium.

    PubMed

    Lee, Wen-Chung

    2015-07-01

    To detect gene-environment interactions, a logistic regression model is typically fitted to a set of case-control data, and the focus is on testing of the cross-product terms (gene × environment) in the model. A significant result is indicative of a gene-environment interaction under a multiplicative model for disease odds. Based on the sufficient-cause model for rates, in this paper we put forward a general approach to testing for sufficient-cause gene-environment interactions in case-control studies. The proposed tests can be tailored to detect a particular type of sufficient-cause gene-environment interaction with greater sensitivity. These tests include testing for autosomal dominant, autosomal recessive, and gene-dosage interactions. The tests can also detect trend interactions (e.g., a larger gene-environment interaction with a higher level of environmental exposure) and threshold interactions (e.g., gene-environment interaction occurs only when environmental exposure reaches a certain threshold level). Two assumptions are necessary for the validity of the tests: 1) the rare-disease assumption and 2) the no-redundancy assumption. Another 2 assumptions are optional but, if imposed correctly, can boost the statistical powers of the tests: 3) the gene-environment independence assumption and 4) the Hardy-Weinberg equilibrium assumption. SAS code (SAS Institute, Inc., Cary, North Carolina) for implementing the methods is provided. PMID:26025233

  20. Gene?environment interactions in parkinsonism and Parkinson's disease: the Geoparkinson study

    PubMed Central

    Dick, F D; De Palma, G; Ahmadi, A; Osborne, A; Scott, N W; Prescott, G J; Bennett, J; Semple, S; Dick, S; Mozzoni, P; Haites, N; Wettinger, S Bezzina; Mutti, A; Otelea, M; Seaton, A; Soderkvist, P; Felice, A

    2007-01-01

    Objectives To investigate associations of Parkinson's disease (PD) and parkinsonian syndromes with polymorphic genes that influence metabolism of either foreign chemical substances or dopamine and to seek evidence of gene?environment interaction effects that modify risk. Methods A case?control study of 959 prevalent cases of parkinsonism (767 with PD) and 1989 controls across five European centres. Occupational hygienists estimated the average annual intensity of exposure to solvents, pesticides and metals, (iron, copper, manganese), blind to disease status. CYP2D6, PON1, GSTM1, GSTT1, GSTM3, GSTP1, NQO1, CYP1B1, MAO?A, MAO?B, SOD 2, EPHX,DAT1, DRD2 and NAT2 were genotyped. Results were analysed using multiple logistic regression adjusting for key confounders. Results There was a modest but significant association between MAO?A polymorphism in males and disease risk (G vs T, OR 1.30, 95% CI 1.02 to 1.66, adjusted). The majority of gene?environment analyses did not show significant interaction effects. There were possible interaction effects between GSTM1 null genotype and solvent exposure (which were stronger when limited to PD cases only). Conclusions Many small studies have reported associations between genetic polymorphisms and PD. Fewer have examined gene?environment interactions. This large study was sufficiently powered to examine these aspects. GSTM1 null subjects heavily exposed to solvents appear to be at increased risk of PD. There was insufficient evidence that the other gene?environment combinations investigated modified disease risk, suggesting they contribute little to the burden of PD. PMID:17449559

  1. Identifying gene-environment and gene-gene interactions using a progressive penalization approach

    PubMed Central

    Zhu, Ruoqing; Zhao, Hongyu; Ma, Shuangge

    2015-01-01

    In genomic studies, identifying important gene-environment and gene-gene interactions is a challenging problem. In this study, we adopt the statistical modeling approach, where interactions are represented by product terms in regression models. For the identification of important interactions, we adopt penalization, which has been used in many genomic studies. Straightforward application of penalization does not respect the “main effect, interaction” hierarchical structure. A few recently proposed methods respect this structure by applying constrained penalization. However, they demand very complicated computational algorithms and can only accommodate a small number of genomic measurements. We propose a computationally fast penalization method that can identify important gene-environment and gene-gene interactions and respect a strong hierarchical structure. The method takes a stagewise approach and progressively expands its optimization domain to account for possible hierarchical interactions. It is applicable to multiple data types and models. A coordinate descent method is utilized to produce the entire regularized solution path. Simulation study demonstrates the superior performance of the proposed method. We analyze a lung cancer prognosis study with gene expression measurements and identify important gene-environment interactions. PMID:24723356

  2. Gene-environment interaction in panic disorder and posttraumatic stress disorder.

    PubMed

    Battaglia, Marco

    2013-02-01

    Gene-environment interaction is a form of causal interplay, whereby genetic effects on phenotypic variation change as a function of environmental exposure. While conceptually appealing, there is still much debate on the veracity and the relevance of this form of etiological interdependence for psychiatric disorders. By focusing on panic disorder (PD) and posttraumatic stress disorder (PTSD), this article outlines why gene-environment interaction is controversial, why it can be important for both researchers and clinicians, and how it is investigated by quantitative genetic, molecular genetic, and genomic strategies. It is suggested that gene-environment interaction effects are more reliable and meaningful when they can be harnessed to pinpoint specific biological pathways and mechanisms. In psychiatry, this can be guided by phenotypic dissection and realized by adopting intermediate phenotypes of a physiological nature, such as carbon dioxide sensitivity for PD, or gene expression profiling after stress for PTSD. A developmental framework of reference and the possibility of transferring the investigation to animal models are additional key elements in this debate. PMID:23442892

  3. Correlation

    NSDL National Science Digital Library

    Anderson-Cook, C.

    The applets, created by Virginia Tech's Department of Statistics, allow you to see how different bivariate data look under different correlation structures. The "Movie" applet either creates data for a particular correlation or animates a multitude data sets ranging correlations from -1 to 1. The "Creation" applet allows the user to create a data set by adding or deleting points from the screen.

  4. Genome-Wide Meta-Analysis of Joint Tests for Genetic and Gene-Environment Interaction Effects

    Microsoft Academic Search

    Hugues Aschard; Dana B. Hancock; Stephanie J. London; Peter Kraft

    2010-01-01

    Background: There is growing interest in the study of gene-environment interactions in the context of genome-wide association studies (GWASs). These studies will likely require meta-analytic approaches to have sufficient power. Methods: We describe an approach for meta-analysis of a joint test for genetic main effects and gene-environment interaction effects. Using simulation studies based on a meta-analysis of five studies (total

  5. A screening-testing approach for detecting gene-environment interactions using sequential penalized and unpenalized multiple logistic regression.

    PubMed

    Frost, H Robert; Andrew, Angeline S; Karagas, Margaret R; Moore, Jason H

    2015-01-01

    Gene-environment (G × E) interactions are biologically important for a wide range of environmental exposures and clinical outcomes. Because of the large number of potential interactions in genomewide association data, the standard approach fits one model per G × E interaction with multiple hypothesis correction (MHC) used to control the type I error rate. Although sometimes effective, using one model per candidate G × E interaction test has two important limitations: low power due to MHC and omitted variable bias. To avoid the coefficient estimation bias associated with independent models, researchers have used penalized regression methods to jointly test all main effects and interactions in a single regression model. Although penalized regression supports joint analysis of all interactions, can be used with hierarchical constraints, and offers excellent predictive performance, it cannot assess the statistical significance of G × E interactions or compute meaningful estimates of effect size. To address the challenge of low power, researchers have separately explored screening-testing, or two-stage, methods in which the set of potential G × E interactions is first filtered and then tested for interactions with MHC only applied to the tests actually performed in the second stage. Although two-stage methods are statistically valid and effective at improving power, they still test multiple separate models and so are impacted by MHC and biased coefficient estimation. To remedy the challenges of both poor power and omitted variable bias encountered with traditional G × E interaction detection methods, we propose a novel approach that combines elements of screening-testing and hierarchical penalized regression. Specifically, our proposed method uses, in the first stage, an elastic net-penalized multiple logistic regression model to jointly estimate either the marginal association filter statistic or the gene-environment correlation filter statistic for all candidate genetic markers. In the second stage, a single multiple logistic regression model is used to jointly assess marginal terms and G × E interactions for all genetic markers that pass the first stage filter. A single likelihood-ratio test is used to determine whether any of the interactions are statistically significant. We demonstrate the efficacy of our method relative to alternative G × E detection methods on a bladder cancer data set. PMID:25592580

  6. Passive euthanasia

    PubMed Central

    Garrard, E; Wilkinson, S

    2005-01-01

    The idea of passive euthanasia has recently been attacked in a particularly clear and explicit way by an "Ethics Task Force" established by the European Association of Palliative Care (EAPC) in February 2001. It claims that the expression "passive euthanasia" is a contradiction in terms and hence that there can be no such thing. This paper critically assesses the main arguments for the Task Force's view. Three arguments are considered. Firstly, an argument based on the (supposed) wrongness of euthanasia and the (supposed) permissibility of what is often called passive euthanasia. Secondly, the claim that passive euthanasia (so-called) cannot really be euthanasia because it does not cause death. And finally, a consequence based argument which appeals to the (alleged) bad consequences of accepting the category of passive euthanasia. We conclude that although healthcare professionals' nervousness about the concept of passive euthanasia is understandable, there is really no reason to abandon the category provided that it is properly and narrowly understand and provided that "euthanasia reasons" for withdrawing or withholding life-prolonging treatment are carefully distinguished from other reasons. PMID:15681666

  7. [The role of gene-environment interaction in the development of eating disorders].

    PubMed

    Gáti, Agnes; Abrahám, Ildikó

    2009-01-01

    The biological research predominant in the last decades have not brought a solution in the discovery of risk factors contributing to the development of eating disorders, and elaborating a more effective therapy. The large amount of molecular genetic studies, however, by showing the various genetic vulnerability, contributed significantly to recognizing a more specific effect of the environmental factors. The authors evaluate the genetic studies of eating disorders and present environmental factors having a role in the development of eating disorders. They report about recently published data of gene-environment interaction and conclude from the data clinically applicable consequences. PMID:19949244

  8. Using Bayesian networks to discover relations between genes, environment, and disease

    PubMed Central

    2013-01-01

    We review the applicability of Bayesian networks (BNs) for discovering relations between genes, environment, and disease. By translating probabilistic dependencies among variables into graphical models and vice versa, BNs provide a comprehensible and modular framework for representing complex systems. We first describe the Bayesian network approach and its applicability to understanding the genetic and environmental basis of disease. We then describe a variety of algorithms for learning the structure of a network from observational data. Because of their relevance to real-world applications, the topics of missing data and causal interpretation are emphasized. The BN approach is then exemplified through application to data from a population-based study of bladder cancer in New Hampshire, USA. For didactical purposes, we intentionally keep this example simple. When applied to complete data records, we find only minor differences in the performance and results of different algorithms. Subsequent incorporation of partial records through application of the EM algorithm gives us greater power to detect relations. Allowing for network structures that depart from a strict causal interpretation also enhances our ability to discover complex associations including gene-gene (epistasis) and gene-environment interactions. While BNs are already powerful tools for the genetic dissection of disease and generation of prognostic models, there remain some conceptual and computational challenges. These include the proper handling of continuous variables and unmeasured factors, the explicit incorporation of prior knowledge, and the evaluation and communication of the robustness of substantive conclusions to alternative assumptions and data manifestations. PMID:23514120

  9. Testing Gene-Environment Interaction in Large-Scale Case-Control Association Studies: Possible Choices and Comparisons

    PubMed Central

    Mukherjee, Bhramar; Ahn, Jaeil; Gruber, Stephen B.; Chatterjee, Nilanjan

    2012-01-01

    Several methods for screening gene-environment interaction have recently been proposed that address the issue of using gene-environment independence in a data-adaptive way. In this report, the authors present a comparative simulation study of power and type I error properties of 3 classes of procedures: 1) the standard 1-step case-control method; 2) the case-only method that requires an assumption of gene-environment independence for the underlying population; and 3) a variety of hybrid methods, including empirical-Bayes, 2-step, and model averaging, that aim at gaining power by exploiting the assumption of gene-environment independence and yet can protect against false positives when the independence assumption is violated. These studies suggest that, although the case-only method generally has maximum power, it has the potential to create substantial false positives in large-scale studies even when a small fraction of markers are associated with the exposure under study in the underlying population. All the hybrid methods perform well in protecting against such false positives and yet can retain substantial power advantages over standard case-control tests. The authors conclude that, for future genome-wide scans for gene-environment interactions, major power gain is possible by using alternatives to standard case-control analysis. Whether a case-only type scan or one of the hybrid methods should be used depends on the strength and direction of gene-environment interaction and association, the level of tolerance for false positives, and the nature of replication strategies. PMID:22199027

  10. Epigenetics of Stress-Related Psychiatric Disorders and Gene × Environment Interactions.

    PubMed

    Klengel, Torsten; Binder, Elisabeth B

    2015-06-17

    A deeper understanding of the pathomechanisms leading to stress-related psychiatric disorders is important for the development of more efficient preventive and therapeutic strategies. Epidemiological studies indicate a combined contribution of genetic and environmental factors in the risk for disease. The environment, particularly early life severe stress or trauma, can lead to lifelong molecular changes in the form of epigenetic modifications that can set the organism off on trajectories to health or disease. Epigenetic modifications are capable of shaping and storing the molecular response of a cell to its environment as a function of genetic predisposition. This provides a potential mechanism for gene-environment interactions. Here, we review epigenetic mechanisms associated with the response to stress and trauma exposure and the development of stress-related psychiatric disorders. We also look at how they may contribute to our understanding of the combined effects of genetic and environmental factors in shaping disease risk. PMID:26087162

  11. Gene-environment interactions, folate metabolism and the embryonic nervous system.

    PubMed

    Ross, M Elizabeth

    2010-01-01

    Formation of brain and spinal cord requires the successful closure of neural ectoderm into an embryonic neural tube. Defects in this process result in anencephaly or spina bifida, which together constitute a leading cause of mortality and morbidity in children, affecting all ethnic and socioeconomic groups. The subject of intensive research for decades, neural tube defects (NTDs), are understood to arise from complex interactions of genes and environmental conditions, though systems-level details are still elusive. Despite the variety of underlying causes, a single intervention, folic acid supplementation given in the first gestational month, can measurably reduce the occurrence of NTDs in a population. Evidence for and the scope of gene-environment interactions in the genesis of NTDs is discussed. A systems-based approach is now possible toward studies of genetic and environmental influences underlying NTDs that will enable the assessment of individual risk and personalized optimization of prevention. PMID:20836042

  12. Gene-Environment Interaction in the Etiology of Mathematical Ability Using SNP Sets

    PubMed Central

    Kovas, Yulia; Plomin, Robert

    2010-01-01

    Mathematics ability and disability is as heritable as other cognitive abilities and disabilities, however its genetic etiology has received relatively little attention. In our recent genome-wide association study of mathematical ability in 10-year-old children, 10 SNP associations were nominated from scans of pooled DNA and validated in an individually genotyped sample. In this paper, we use a ‘SNP set’ composite of these 10 SNPs to investigate gene-environment (GE) interaction, examining whether the association between the 10-SNP set and mathematical ability differs as a function of ten environmental measures in the home and school in a sample of 1888 children with complete data. We found two significant GE interactions for environmental measures in the home and the school both in the direction of the diathesis-stress type of GE interaction: The 10-SNP set was more strongly associated with mathematical ability in chaotic homes and when parents are negative. PMID:20978832

  13. An attachment perspective on borderline personality disorder: advances in gene-environment considerations.

    PubMed

    Steele, Howard; Siever, Larry

    2010-02-01

    Accumulating evidence points to severe relationship dysfunction as the core epigenetic expression of borderline personality disorder (BPD). In adulthood, BPD is typified by disorganization within and across interpersonal domains of functioning. When interacting with their infants, mothers with BPD show marked withdrawal and frightening or frightened behavior, leading to disorganized infant-mother attachments. Linked to both infant disorganization and BPD is a maternal state of mind typified by unresolved mourning regarding past loss or trauma. Early risk factors for BPD in adulthood include maternal withdrawal in infancy and separation of 1 month or more from mother in the first 5 years of life. Likely contributing biological factors include genes linked to dopamine, serotonin, the hypothalamic-pituitary-adrenal axis, and neuropeptides. The complex gene-environment picture emerging confers risk or protection against BPD pathology in ways consistent with infants varying biological sensitivity to context. This line of research may refine early risk assessment and preventive mental health services. PMID:20425312

  14. Externalizing Disorders and Environmental Risk: Mechanisms of Gene-Environment Interplay and Strategies for Intervention

    PubMed Central

    Samek, Diana R.; Hicks, Brian M.

    2014-01-01

    Summary Though heritable, externalizing disorders have a number of robust associations with several environmental risk factors, including family, school, and peer contexts. To account for these associations, we integrate a behavioral genetic perspective with principles of a developmental cascade theory of antisocial behavior. The major environmental contexts associated with child externalizing problems are reviewed, as are the processes of gene-environment interplay underlying these associations. Throughout, we discuss implications for prevention and intervention. Three major approaches designed to reduce child externalizing behavior are reviewed. Prevention and intervention programs appear to be most successful when they target individuals or communities most at risk for developing externalizing disorders, rather than applied universally. We end by commenting on areas in need of additional research concerning environmental influences on persistent externalizing behaviors. PMID:25485087

  15. MAOA, childhood maltreatment and antisocial behavior: Meta-analysis of a gene-environment interaction

    PubMed Central

    Byrd, Amy L.; Manuck, Stephen B.

    2013-01-01

    Background In a seminal study of gene-environment interaction, childhood maltreatment predicted antisocial behavior more strongly in males carrying an MAOA promoter variant of lesser, compared to higher, transcriptional efficiency. Many further investigations have been reported, including studies of other early environmental exposures and females. Here we report a meta-analysis of studies testing the interaction of MAOA genotype and childhood adversities on antisocial outcomes in predominantly non-clinical samples. Method Included were 27 peer-reviewed, English-language studies published through August, 2012, that contained indicators of maltreatment or “other” family (e.g., parenting, sociodemographic) hardships; MAOA genotype; indices of aggressive and antisocial behavior; and statistical test of genotype-environment interaction. Studies of forensic and exclusively clinical samples, clinical cohorts lacking proportionally matched controls, or outcomes non-specific for antisocial behavior were excluded. The Liptak-Stouffer weighted Z-test for meta-analysis was implemented to maximize study inclusion and calculated separately for male and female cohorts. Results Across 20 male cohorts, early adversity presaged antisocial outcomes more strongly for low, relative to high, activity MAOA genotype (P=.0044). Stratified analyses showed the interaction specific to maltreatment (P=.0000008) and robust to several sensitivity analyses. Across 11 female cohorts, MAOA did not interact with combined early life adversities, whereas maltreatment alone predicted antisocial behaviors preferentially, but weakly, in females of high activity MAOA genotype (P=.02). Conclusions We found common regulatory variation in MAOA to moderate effects of childhood maltreatment on male antisocial behaviors, confirming a sentinel finding in research on gene-environment interaction. An analogous, but less consistent, finding in females warrants further investigation. PMID:23786983

  16. Localized photoelectrochemical measurements of passive filmson titanium

    SciTech Connect

    Butler, M.A.

    1983-12-01

    Using a focused laser and a digitally controlled x-y stage, localized photoelectrochemical measurements have been made on 100A thick passive films on polycrystalline titanium. The photocurrent dependence on potential is semiquantitatively explained by a model considering trap dominated electronic charge transport in the passive film. Variations in the measured electronic properties are observed which correlate with the underlying metal grain structure. The data suggest extremely high trap densities in the passivating film.

  17. Gene-Environment Interactions across Development: Exploring DRD2 Genotype and Prenatal Smoking Effects on Self-Regulation

    ERIC Educational Resources Information Center

    Wiebe, Sandra A.; Espy, Kimberly Andrews; Stopp, Christian; Respass, Jennifer; Stewart, Peter; Jameson, Travis R.; Gilbert, David G.; Huggenvik, Jodi I.

    2009-01-01

    Genetic factors dynamically interact with both pre- and postnatal environmental influences to shape development. Considerable attention has been devoted to gene-environment interactions (G x E) on important outcomes (A. Caspi & T. E. Moffitt, 2006). It is also important to consider the possibility that these G x E effects may vary across…

  18. Gene-Environment Interaction in Externalizing Problems among Adolescents: Evidence from the Pelotas 1993 Birth Cohort Study

    ERIC Educational Resources Information Center

    Kieling, Christian; Hutz, Mara H.; Genro, Julia P.; Polanczyk, Guilherme V.; Anselmi, Luciana; Camey, Suzi; Hallal, Pedro C.; Barros, Fernando C.; Victora, Cesar G.; Menezes, Ana M. B.; Rohde, Luis Augusto

    2013-01-01

    Background: The study of gene-environment interactions (G by E) is one of the most promising strategies to uncover the origins of mental disorders. Replication of initial findings, however, is essential because there is a strong possibility of publication bias in the literature. In addition, there is a scarcity of research on the topic originated…

  19. An Interdisciplinary Approach to Studying Gene–Environment Interactions: From Twin Studies to Gene Identification and Back

    Microsoft Academic Search

    Danielle M. Dick

    2011-01-01

    There has been a surge of interest in studying gene–environment interaction; however, research in this area faces a number of challenges. Interdisciplinary collaborations are critical at this juncture. This article reviews studies that illustrate how findings across different literatures can be synthesized to characterize how genetic and environmental influences impact developmental pathways. Developmental scientists are poised to make important contributions

  20. A database of gene-environment interactions pertaining to blood lipid traits, cardiovascular disease and type 2 diabetes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As the role of the environment – diet, exercise, alcohol and tobacco use and sleep among others – is accorded a more prominent role in modifying the relationship between genetic variants and clinical measures of disease, consideration of gene-environment (GxE) interactions is a must. To facilitate i...

  1. Passive interspectroscopy

    SciTech Connect

    Bagnuolo, W.G. Jr.; Kamper, K.W. (Georgia State Univ., Atlanta (USA) David Dunlap Observatory, Richmond Hill (Canada))

    1990-03-01

    'Interspectroscopy' is a method of obtaining the separated spectra of binary (or multiple) stars too close to be resolved by conventional techniques. The method is 'passive' because, like speckle interferometry, the atmosphere provides a series of random phase variations, and no control system is used to maintain phase. Results in terms of spectral purity are given for several cases in both the pupil and image planes. It is shown that significant spectral separation can occur. Planned observations with a fiber-fed, pulse-counting spectrograph at the 1.9-m DDO telescope are discussed. 19 refs.

  2. CardioGxE, a catalog of gene-environment interactions for cardiometabolic traits

    PubMed Central

    2014-01-01

    Background Genetic understanding of complex traits has developed immensely over the past decade but remains hampered by incomplete descriptions of contribution to phenotypic variance. Gene-environment (GxE) interactions are one of these contributors and in the guise of diet and physical activity are important modulators of cardiometabolic phenotypes and ensuing diseases. Results We mined the scientific literature to collect GxE interactions from 386 publications for blood lipids, glycemic traits, obesity anthropometrics, vascular measures, inflammation and metabolic syndrome, and introduce CardioGxE, a gene-environment interaction resource. We then analyzed the genes and SNPs supporting cardiometabolic GxEs in order to demonstrate utility of GxE SNPs and to discern characteristics of these important genetic variants. We were able to draw many observations from our extensive analysis of GxEs. 1) The CardioGxE SNPs showed little overlap with variants identified by main effect GWAS, indicating the importance of environmental interactions with genetic factors on cardiometabolic traits. 2) These GxE SNPs were enriched in adaptation to climatic and geographical features, with implications on energy homeostasis and response to physical activity. 3) Comparison to gene networks responding to plasma cholesterol-lowering or regression of atherosclerotic plaques showed that GxE genes have a greater role in those responses, particularly through high-energy diets and fat intake, than do GWAS-identified genes for the same traits. Other aspects of the CardioGxE dataset were explored. Conclusions Overall, we demonstrate that SNPs supporting cardiometabolic GxE interactions often exhibit transcriptional effects or are under positive selection. Still, not all such SNPs can be assigned potential functional or regulatory roles often because data are lacking in specific cell types or from treatments that approximate the environmental factor of the GxE. With research on metabolic related complex disease risk embarking on genome-wide GxE interaction tests, CardioGxE will be a useful resource. PMID:25368670

  3. Bayesian variable selection for hierarchical gene-environment and gene-gene interactions.

    PubMed

    Liu, Changlu; Ma, Jianzhong; Amos, Christopher I

    2015-01-01

    We propose a Bayesian hierarchical mixture model framework that allows us to investigate the genetic and environmental effects, gene by gene interactions and gene by environment interactions in the same model. Our approach incorporates the natural hierarchical structure between the main effects and interaction effects into a mixture model, such that our methods tend to remove the irrelevant interaction effects more effectively, resulting in more robust and parsimonious models. We consider both strong and weak hierarchical models. For a strong hierarchical model, both the main effects between interacting factors must be present for the interactions to be considered in the model development, while for a weak hierarchical model, only one of the two main effects is required to be present for the interaction to be evaluated. Our simulation results show that the proposed strong and weak hierarchical mixture models work well in controlling false-positive rates and provide a powerful approach for identifying the predisposing effects and interactions in gene-environment interaction studies, in comparison with the naive model that does not impose this hierarchical constraint in most of the scenarios simulated. We illustrate our approach using data for lung cancer and cutaneous melanoma. PMID:25154630

  4. Gene-Environment Interaction and Covariation in Schizophrenia: The Role of Obstetric Complications

    PubMed Central

    Mittal, Vijay A.; Ellman, Lauren M.; Cannon, Tyrone D.

    2008-01-01

    While genetic factors account for a significant proportion of liability to schizophrenia, a body of evidence attests to a significant environmental contribution. Understanding the mechanisms through which genetic and environmental factors coalesce in influencing schizophrenia is critical for elucidating the pathways underlying psychotic illness and for developing primary prevention strategies. Although obstetric complications (OCs) remain among the most well-documented environmental indicators of risk for schizophrenia, the pathogenic role they play in the etiology of schizophrenia continues to remain poorly understood. A question of major importance is do these factors result from a genetic diathesis to schizophrenia (as in gene-environment covariation), act additively or interactively with predisposing genes for the disorder in influencing disease risk, or independently cause disease onset? In this review, we evaluate 3 classes of OCs commonly related to schizophrenia including hypoxia-associated OCs, maternal infection during pregnancy, and maternal stress during pregnancy. In addition, we discuss several mechanisms by which OCs impact on genetically susceptible brain regions, increasing constitutional vulnerability to neuromaturational events and stressors later in life (ie, adolescence), which may in turn contribute to triggering psychosis. PMID:18635675

  5. Gene-environment interaction in major depression: focus on experience-dependent biological systems.

    PubMed

    Lopizzo, Nicola; Bocchio Chiavetto, Luisella; Cattane, Nadia; Plazzotta, Giona; Tarazi, Frank I; Pariante, Carmine M; Riva, Marco A; Cattaneo, Annamaria

    2015-01-01

    Major depressive disorder (MDD) is a multifactorial and polygenic disorder, where multiple and partially overlapping sets of susceptibility genes interact each other and with the environment, predisposing individuals to the development of the illness. Thus, MDD results from a complex interplay of vulnerability genes and environmental factors that act cumulatively throughout individual's lifetime. Among these environmental factors, stressful life experiences, especially those occurring early in life, have been suggested to exert a crucial impact on brain development, leading to permanent functional changes that may contribute to lifelong risk for mental health outcomes. In this review, we will discuss how genetic variants (polymorphisms, SNPs) within genes operating in neurobiological systems that mediate stress response and synaptic plasticity, can impact, by themselves, the vulnerability risk for MDD; we will also consider how this MDD risk can be further modulated when gene?×?environment interaction is taken into account. Finally, we will discuss the role of epigenetic mechanisms, and in particular of DNA methylation and miRNAs expression changes, in mediating the effect of the stress on the vulnerability risk to develop MDD. Taken together, we aim to underlie the role of genetic and epigenetic processes involved in stress- and neuroplasticity-related biological systems on the development of MDD after exposure to early life stress, thereby building the basis for future research and clinical interventions. PMID:26005424

  6. Gene-Environment Interplay in the Association between Pubertal Timing and Delinquency in Adolescent Girls

    PubMed Central

    Harden, K. Paige; Mendle, Jane

    2014-01-01

    Early pubertal timing places girls at elevated risk for a breadth of negative outcomes, including involvement in delinquent behavior. While previous developmental research has emphasized the unique social challenges faced by early maturing girls, this relation is complicated by genetic influences for both delinquent behavior and pubertal timing, which are seldom controlled for in existing research. The current study uses genetically informed data on 924 female-female twin and sibling pairs drawn from the National Longitudinal Study of Adolescent Health to (1) disentangle biological versus environmental mechanisms for the effects of early pubertal timing and (2) test for gene-environment interactions. Results indicate that early pubertal timing influences girls’ delinquency through a complex interplay between biological risk and environmental experiences. Genes related to earlier age at menarche and higher perceived development significantly predict increased involvement in both non-violent and violent delinquency. Moreover, after accounting for this genetic association between pubertal timing and delinquency, the impact of non-shared environmental influences on delinquency are significantly moderated by pubertal timing, such that the non-shared environment is most important among early maturing girls. This interaction effect is particularly evident for non-violent delinquency. Overall, results suggest early maturing girls are vulnerable to an interaction between genetic and environmental risks for delinquent behavior. PMID:21668078

  7. Gene–Environment Interactions and Response to Social Intrusion in Male and Female Rhesus Macaques

    PubMed Central

    Schwandt, Melanie L.; Lindell, Stephen G.; Sjöberg, Rickard L.; Chisholm, Kelli L.; Higley, J. Dee; Suomi, Stephen J.; Heilig, Markus; Barr, Christina S.

    2010-01-01

    Background Genetic factors interact with environmental stressors to moderate risk for human psychopathology, but sex may also be an important mediating factor. Different strategies for coping with environmental stressors have evolved in males and females, and these differences may underlie the differential prevalence of certain types of psychopathology in the two sexes. In this study, we investigated the possibility of sex-specific gene–environment interactions in a nonhuman primate model of response to social threat. Methods Rhesus macaques (77 males and 106 females) were exposed to an unfamiliar conspecific. Using factor analysis, we identified three behavioral factors characterizing the response to social threat. Monkeys were genotyped for the serotonin transporter–linked polymorphism (5-HTTLPR), and the effects of genotype, early life stress, and sex on behavioral responses were evaluated. Results Factor analysis produced five factors: High-Risk Aggression, Impulsivity/Novelty-Seeking, Gregariousness/Boldness, Harm Avoidance, and Redirected Aggression. Overall, males displayed higher levels of High-Risk Aggression and Gregariousness/Boldness than females. Levels of High-Risk Aggression in males carrying the s allele were significantly higher if they were also exposed to early adversity in the form of peer rearing. Conclusions Our findings support those from studies in humans suggesting that males are more vulnerable to externalizing or aggression-related disorders. The results highlight the importance of interactions that exist among behavior, genes, and the environment and suggest that sex differences in vulnerability to psychopathology may be grounded in our evolutionary history. PMID:20015482

  8. REVIEW: Genome-wide findings in schizophrenia and the role of gene-environment interplay.

    PubMed

    Van Winkel, Ruud; Esquivel, Gabriel; Kenis, Gunter; Wichers, Marieke; Collip, Dina; Peerbooms, Odette; Rutten, Bart; Myin-Germeys, Inez; Van Os, Jim

    2010-10-01

    The recent advent of genome-wide mass-marker technology has resulted in renewed optimism to unravel the genetic architecture of psychotic disorders. Genome-wide association studies have identified a number of common polymorphisms robustly associated with schizophrenia, in ZNF804A, transcription factor 4, major histocompatibility complex, and neurogranin. In addition, copy number variants (CNVs) in 1q21.1, 2p16.3, 15q11.2, 15q13.3, 16p11.2, and 22q11.2 were convincingly implicated in schizophrenia risk. Furthermore, these studies have suggested considerable genetic overlap with bipolar disorder (particularly for common polymorphisms) and neurodevelopmental disorders such as autism (particularly for CNVs). The influence of these risk variants on relevant intermediate phenotypes needs further study. In addition, there is a need for etiological models of psychosis integrating genetic risk with environmental factors associated with the disorder, focusing specifically on environmental impact on gene expression (epigenetics) and convergence of genes and environment on common biological pathways bringing about larger effects than those of genes or environment in isolation (gene-environment interaction). Collaborative efforts that bring together expertise in statistics, genetics, epidemiology, experimental psychiatry, brain imaging, and clinical psychiatry will be required to succeed in this challenging task. PMID:20553308

  9. Gene–environment interactions: early life stress and risk for depressive and anxiety disorders

    PubMed Central

    Tyrka, Audrey R.; Carpenter, Linda L.; Price, Lawrence H.

    2013-01-01

    Rationale Prior reviews have examined how stress, broadly defined, interacts with genetic diathesis in the pathogenesis of internalizing (i.e., depressive and anxiety) disorders. Recent findings have suggested a unique role for early life stress (ELS) in the development of internalizing disorders, contributing to the rapid proliferation of research in this area. Objective This paper critically reviews studies in humans examining gene–environment interaction (GxE) effects of ELS on the risk for depression and anxiety, primarily from a candidate gene perspective. Major methodological challenges that are unique to such studies are considered. Results The majority of published studies have focused on candidates that regulate the serotonin system, especially the serotonin transporter. More recent work has addressed interactions of ELS with candidates from the hypothalamic-pituitary-adrenal axis and neurotrophin system. Available studies vary greatly with respect to definitions of ELS, examination of gene–gene interactions, consideration of gender effects, and attention to analytic limitations. Conclusions Overall, there is support for GxE effects of ELS on the risk for depressive and anxiety outcomes. Future studies of ELS in this context will require careful attention to methodologic considerations. Such studies would benefit from more systematic assessment of positive environmental factors (e.g., social support) and greater utilization of developmentally sensitive paradigms. PMID:21225419

  10. Environmental factors as modulators of neurodegeneration: insights from gene-environment interactions in Huntington's disease.

    PubMed

    Mo, Christina; Hannan, Anthony J; Renoir, Thibault

    2015-05-01

    Unlike many other neurodegenerative diseases with established gene-environment interactions, Huntington's disease (HD) is viewed as a disorder governed by genetics. The cause of the disease is a highly penetrant tandem repeat expansion encoding an extended polyglutamine tract in the huntingtin protein. In the year 2000, a pioneering study showed that the disease could be delayed in transgenic mice by enriched housing conditions. This review describes subsequent human and preclinical studies identifying environmental modulation of motor, cognitive, affective and other symptoms found in HD. Alongside the behavioral observations we also discuss potential mechanisms and the relevance to other neurodegenerative disorders, including Alzheimer's and Parkinson's disease. In mouse models of HD, increased sensorimotor and cognitive stimulation can delay or ameliorate various endophenotypes. Potential mechanisms include increased trophic support, synaptic plasticity, adult neurogenesis, and other forms of experience-dependent cellular plasticity. Subsequent clinical investigations support a role for lifetime activity levels in modulating the onset and progression of HD. Stress can accelerate memory and olfactory deficits and exacerbate cellular dysfunctions in HD mice. In the absence of effective treatments to slow the course of HD, environmental interventions offer feasible approaches to delay the disease, however further preclinical and human studies are needed in order to generate clinical recommendations. Environmental interventions could be combined with future pharmacological therapies and stimulate the identification of enviromimetics, drugs which mimic or enhance the beneficial effects of cognitive stimulation and physical activity. PMID:25770041

  11. Passive ocean acoustic tomography

    NASA Astrophysics Data System (ADS)

    Godin, O. A.; Goncharov, V. V.; Zabotin, N. A.

    2012-05-01

    The possibility to apply natural acoustic ocean noise in the ocean and noise of distant vessels as sounding signals in order to determine the physical parameters of a water layer is considered in this paper. We developed the methods making it possible to suppress the non-diffuse components of noise produced, e.g., by local vessels and to account for hydrophone motion. These methods are applied to the noise records obtained in the course of a year-long experiment on long-range sound propagation in the Pacific Ocean. We confirmed experimentally our theoretical predictions as to the possibility of retrieving deterministic acoustic ray travel times in a nonuniform environment from a mutual correlation function of imperfectly diffuse (gradually anisotropic and spatially nonuniform) noise without invoking any data on its source. We performed passive measurements of sound velocity in the ocean with a relative error of about 0.1% by correlation of noise fields recorded with vertical aerials. This accuracy approaches that needed for oceanological applications. Further investigations are necessary to study the feasibility of passive acoustic tomography and thermometry in the ocean at distances of tens and hundreds of kilometers and the possibility to use simpler arrays not equipped with hydrophone positioning systems.

  12. Identification of new genetic susceptibility loci for breast cancer through consideration of gene-environment interactions.

    PubMed

    Schoeps, Anja; Rudolph, Anja; Seibold, Petra; Dunning, Alison M; Milne, Roger L; Bojesen, Stig E; Swerdlow, Anthony; Andrulis, Irene; Brenner, Hermann; Behrens, Sabine; Orr, Nicholas; Jones, Michael; Ashworth, Alan; Li, Jingmei; Cramp, Helen; Connley, Dan; Czene, Kamila; Darabi, Hatef; Chanock, Stephen J; Lissowska, Jolanta; Figueroa, Jonine D; Knight, Julia; Glendon, Gord; Mulligan, Anna M; Dumont, Martine; Severi, Gianluca; Baglietto, Laura; Olson, Janet; Vachon, Celine; Purrington, Kristen; Moisse, Matthieu; Neven, Patrick; Wildiers, Hans; Spurdle, Amanda; Kosma, Veli-Matti; Kataja, Vesa; Hartikainen, Jaana M; Hamann, Ute; Ko, Yon-Dschun; Dieffenbach, Aida K; Arndt, Volker; Stegmaier, Christa; Malats, Núria; Arias Perez, José I; Benítez, Javier; Flyger, Henrik; Nordestgaard, Børge G; Truong, Thérèse; Cordina-Duverger, Emilie; Menegaux, Florence; dos Santos Silva, Isabel; Fletcher, Olivia; Johnson, Nichola; Häberle, Lothar; Beckmann, Matthias W; Ekici, Arif B; Braaf, Linde; Atsma, Femke; van den Broek, Alexandra J; Makalic, Enes; Schmidt, Daniel F; Southey, Melissa C; Cox, Angela; Simard, Jacques; Giles, Graham G; Lambrechts, Diether; Mannermaa, Arto; Brauch, Hiltrud; Guénel, Pascal; Peto, Julian; Fasching, Peter A; Hopper, John; Flesch-Janys, Dieter; Couch, Fergus; Chenevix-Trench, Georgia; Pharoah, Paul D P; Garcia-Closas, Montserrat; Schmidt, Marjanka K; Hall, Per; Easton, Douglas F; Chang-Claude, Jenny

    2014-01-01

    Genes that alter disease risk only in combination with certain environmental exposures may not be detected in genetic association analysis. By using methods accounting for gene-environment (G × E) interaction, we aimed to identify novel genetic loci associated with breast cancer risk. Up to 34,475 cases and 34,786 controls of European ancestry from up to 23 studies in the Breast Cancer Association Consortium were included. Overall, 71,527 single nucleotide polymorphisms (SNPs), enriched for association with breast cancer, were tested for interaction with 10 environmental risk factors using three recently proposed hybrid methods and a joint test of association and interaction. Analyses were adjusted for age, study, population stratification, and confounding factors as applicable. Three SNPs in two independent loci showed statistically significant association: SNPs rs10483028 and rs2242714 in perfect linkage disequilibrium on chromosome 21 and rs12197388 in ARID1B on chromosome 6. While rs12197388 was identified using the joint test with parity and with age at menarche (P-values = 3 × 10(-07)), the variants on chromosome 21 q22.12, which showed interaction with adult body mass index (BMI) in 8,891 postmenopausal women, were identified by all methods applied. SNP rs10483028 was associated with breast cancer in women with a BMI below 25 kg/m(2) (OR = 1.26, 95% CI 1.15-1.38) but not in women with a BMI of 30 kg/m(2) or higher (OR = 0.89, 95% CI 0.72-1.11, P for interaction = 3.2 × 10(-05)). Our findings confirm comparable power of the recent methods for detecting G × E interaction and the utility of using G × E interaction analyses to identify new susceptibility loci. PMID:24248812

  13. Study design: Evaluating gene–environment interactions in the etiology of breast cancer – the WECARE study

    PubMed Central

    Bernstein, Jonine L; Langholz, Bryan; Haile, Robert W; Bernstein, Leslie; Thomas, Duncan C; Stovall, Marilyn; Malone, Kathleen E; Lynch, Charles F; Olsen, Jørgen H; Anton-Culver, Hoda; Shore, Roy E; Boice, John D; Berkowitz, Gertrud S; Gatti, Richard A; Teitelbaum, Susan L; Smith, Susan A; Rosenstein, Barry S; Børresen-Dale, Anne-Lise; Concannon, Patrick; Thompson, W Douglas

    2004-01-01

    Introduction Deficiencies in cellular responses to DNA damage can predispose to cancer. Ionizing radiation can cause cluster damage and double-strand breaks (DSBs) that pose problems for cellular repair processes. Three genes (ATM, BRCA1, and BRCA2) encode products that are essential for the normal cellular response to DSBs, but predispose to breast cancer when mutated. Design To examine the joint roles of radiation exposure and genetic susceptibility in the etiology of breast cancer, we designed a case-control study nested within five population-based cancer registries. We hypothesized that a woman carrying a mutant allele in one of these genes is more susceptible to radiation-induced breast cancer than is a non-carrier. In our study, 700 women with asynchronous bilateral breast cancer were individually matched to 1400 controls with unilateral breast cancer on date and age at diagnosis of the first breast cancer, race, and registry region, and counter-matched on radiation therapy. Each triplet comprised two women who received radiation therapy and one woman who did not. Radiation absorbed dose to the contralateral breast after initial treatment was estimated with a comprehensive dose reconstruction approach that included experimental measurements in anthropomorphic and water phantoms applying patient treatment parameters. Blood samples were collected from all participants for genetic analyses. Conclusions Our study design improves the potential for detecting gene–environment interactions for diseases when both gene mutations and the environmental exposures of interest are rare in the general population. This is particularly applicable to the study of bilateral breast cancer because both radiation dose and genetic susceptibility have important etiologic roles, possibly by interactive mechanisms. By using counter-matching, we optimized the informativeness of the collected dosimetry data by increasing the variability of radiation dose within the case–control sets and enhanced our ability to detect radiation–genotype interactions. PMID:15084244

  14. Principal Interactions Analysis for Repeated Measures Data: Application to Gene-Gene, Gene-Environment Interactions

    PubMed Central

    Mukherjee, Bhramar; Ko, Yi-An; Vanderweele, Tyler; Roy, Anindya; Park, Sung Kyun; Chen, Jinbo

    2012-01-01

    Many existing cohorts with longitudinal data on environmental exposures, occupational history, lifestyle/behavioral characteristics and health outcomes have collected genetic data in recent years. In this paper, we consider the problem of modeling gene-gene, gene-environment interactions with repeated measures data on a quantitative trait. We review possibilities of using classical models proposed by Tukey (1949) and Mandel (1961) using the cell means of a two-way classification array for such data. Whereas these models are effective for detecting interactions in presence of main effects, they fail miserably if the interaction structure is misspecified. We explore a more robust class of interaction models that are based on a singular value decomposition of the cell means residual matrix after fitting the additive main effect terms. This class of additive main effects and multiplicative interaction (AMMI) models (Gollob, 1968) provide useful summaries for subject-specific and time-varying effects as represented in terms of their contribution to the leading eigenvalues of the interaction matrix. It also makes the interaction structure more amenable to geometric representation. We call this analysis “Principal Interactions Analysis” (PIA). While the paper primarily focusses on a cell-mean based analysis of repeated measures outcome, we also introduce resampling-based methods that appropriately recognize the unbalanced and longitudinal nature of the data instead of reducing the response to cell-means. The proposed methods are illustrated by using data from the Normative Aging Study, a longitudinal cohort study of Boston area veterans since 1963. We carry out simulation studies under an array of classical interaction models and common epistasis models to illustrate the properties of the PIA procedure in comparison to the classical alternatives. PMID:22415818

  15. A genome-wide gene-environment interaction analysis for tobacco smoke and lung cancer susceptibility.

    PubMed

    Zhang, Ruyang; Chu, Minjie; Zhao, Yang; Wu, Chen; Guo, Huan; Shi, Yongyong; Dai, Juncheng; Wei, Yongyue; Jin, Guangfu; Ma, Hongxia; Dong, Jing; Yi, Honggang; Bai, Jianling; Gong, Jianhang; Sun, Chongqi; Zhu, Meng; Wu, Tangchun; Hu, Zhibin; Lin, Dongxin; Shen, Hongbing; Chen, Feng

    2014-07-01

    Tobacco smoke is the major environmental risk factor underlying lung carcinogenesis. However, approximately one-tenth smokers develop lung cancer in their lifetime indicating there is significant individual variation in susceptibility to lung cancer. And, the reasons for this are largely unknown. In particular, the genetic variants discovered in genome-wide association studies (GWAS) account for only a small fraction of the phenotypic variations for lung cancer, and gene-environment interactions are thought to explain the missing fraction of disease heritability. The ability to identify smokers at high risk of developing cancer has substantial preventive implications. Thus, we undertook a gene-smoking interaction analysis in a GWAS of lung cancer in Han Chinese population using a two-phase designed case-control study. In the discovery phase, we evaluated all pair-wise (591 370) gene-smoking interactions in 5408 subjects (2331 cases and 3077 controls) using a logistic regression model with covariate adjustment. In the replication phase, promising interactions were validated in an independent population of 3023 subjects (1534 cases and 1489 controls). We identified interactions between two single nucleotide polymorphisms and smoking. The interaction P values are 6.73 × 10(-) (6) and 3.84 × 10(-) (6) for rs1316298 and rs4589502, respectively, in the combined dataset from the two phases. An antagonistic interaction (rs1316298-smoking) and a synergetic interaction (rs4589502-smoking) were observed. The two interactions identified in our study may help explain some of the missing heritability in lung cancer susceptibility and present strong evidence for further study of these gene-smoking interactions, which are benefit to intensive screening and smoking cessation interventions. PMID:24658283

  16. Latitudinal Body Size Clines in the Butterfly Polyommatus icarus are Shaped by Gene-Environment Interactions

    PubMed Central

    Nygren, Georg H.; Bergström, Anders; Nylin, Sören

    2008-01-01

    The study of latitudinal body size clines can illuminate processes of local adaptation, but there is a need for an increased understanding of the relative roles of genetic variation, environmental effectstions or this reason, we combined an investigation of a museum collection of the common blue butterfly Polyommatus icarus (Rottemburg) (Lycaenidae: Polyommatini) from Sweden with a common-garden experiment in the laboratory, using strains reared from individuals collected from three different latitudes. Sizes of the field-collected butterflies tended to smoothly decrease northwards in a latitudinal cline, but suddenly increase at the latitude where the life cycle changes from two to one generations per year, hence allowing more time for this single generation. Further north, the size of the field-collected butterflies again decreased with latitude (with the exception of the northernmost collection sites). This is in accordance with the “converse Bergmann” pattern and with the “saw-tooth model” suggesting that insect size is shaped by season length and number of generations along latitudinal transects. In contrast, under laboratory conditions with a constant long day-length there was a different pattern, with the butterflies pupating at a higher mass when individuals originated from southern populations under time stress to achieve a second generation. This is indirect evidence for field patterns being shaped by end-of-season cues cutting development short, and also suggests counter-gradient variation, as butterflies from the time-stressed populations over-compensated for decreasing larval development time by increasing their growth rates, thus obtaining higher mass. Hence, we found support for both adaptive phenotypic plasticity and local genetic adaptation, with gene-environment interactions explaining the observed field patterns.

  17. DISC1 mouse models as a tool to decipher gene-environment interactions in psychiatric disorders

    PubMed Central

    Cash-Padgett, Tyler; Jaaro-Peled, Hanna

    2013-01-01

    DISC1 was discovered in a Scottish pedigree in which a chromosomal translocation that breaks this gene segregates with psychiatric disorders, mainly depression and schizophrenia. Linkage and association studies in diverse populations support DISC1 as a susceptibility gene to a variety of neuropsychiatric disorders. Many Disc1 mouse models have been generated to study its neuronal functions. These mouse models display variable phenotypes, some of them relevant to schizophrenia, others to depression. The Disc1 mouse models are popular genetic models for studying gene-environment interactions in schizophrenia. Five different Disc1 models have been combined with environmental factors. The environmental stressors employed can be classified as either early immune activation or later social paradigms. These studies cover major time points along the neurodevelopmental trajectory: prenatal, early postnatal, adolescence, and adulthood. Various combinations of molecular, anatomical and behavioral methods have been used to assess the outcomes. Additionally, three of the studies sought to rescue the resulting abnormalities. Here we provide background on the environmental paradigms used, summarize the results of these studies combining Disc1 mouse models with environmental stressors and discuss what we can learn and how to proceed. A major question is how the genetic and environmental factors determine which psychiatric disorder will be clinically manifested. To address this we can take advantage of the many Disc1 models available and expose them to the same environmental stressor. The complementary experiment would be to expose the same model to different environmental stressors. DISC1 is an ideal gene for this approach, since in the Scottish pedigree the same chromosomal translocation results in different psychiatric conditions. PMID:24027503

  18. G x E: a NIAAA workshop on gene-environment interactions.

    PubMed

    Gunzerath, Lorraine; Goldman, David

    2003-03-01

    The National Institute on Alcohol Abuse and Alcoholism (NIAAA) sponsored a May 2002 workshop on gene-environment interaction (G x E) research to identify potential roadblocks to further research and to propose solutions to those roadblocks, to optimize investigative opportunities and multidisciplinary or multi-institution collaborations, and to explore ways that NIAAA can facilitate G x E studies. Sessions included panels on animal models; phenotypes; genetic findings in humans; study designs and analytical methods; and assessment of environmental risk. Key among the identified challenges to progress in G x E research were issues of study design and sampling strategies; logistic and methodological costs and constraints; availability and understanding of data analysis techniques; potential stigmatization of study populations; and organizational/bureaucratic structures that are inadequate to address the unique needs of large-scale, multicenter, longitudinal projects. Participants proposed a series of recommendations to address these issues. Session coordinators included: Gayle Boyd, Kendall Bryant, Page Chiapella, Vivian Faden, David Goldman, and Antonio Noronha. Session participants included: Laura Almasy, Henri Begleiter, Raul Caetano, Bruce Dudek, Mary Dufour, Cindy Ehlers, Mary-Anne Enoch, Joel Gelernter, David Goldman, Bridget Grant, Lorraine Gunzerath, Deborah Hasin, Andrew Heath, Victor Hesselbrock, J. Dee Higley, Shirley Hill, Kerry Jang, Raynard S. Kington, Rick Kittles, George Koob, Kenneth Leonard, Ting-Kai Li, Jeffrey Long, William McBride, Matthew McGue, Kathleen Merikangas, Tamara Phillips, Bernice Porjesz, Carol Prescott, Theodore Reich, John Rice, Richard Rose, Charmaine Royal, Arnold Sameroff, Marc Schuckit, Kenneth Sher, Renee Sieving, Robert Taylor, Michael Windle, and Robert Zucker. PMID:12658122

  19. Identification of New Genetic Susceptibility Loci for Breast Cancer Through Consideration of Gene-Environment Interactions

    PubMed Central

    Schoeps, Anja; Rudolph, Anja; Seibold, Petra; Dunning, Alison M.; Milne, Roger L.; Bojesen, Stig E.; Swerdlow, Anthony; Andrulis, Irene; Brenner, Hermann; Behrens, Sabine; Orr, Nicholas; Jones, Michael; Ashworth, Alan; Li, Jingmei; Cramp, Helen; Connley, Dan; Czene, Kamila; Darabi, Hatef; Chanock, Stephen J.; Lissowska, Jolanta; Figueroa, Jonine D.; Knight, Julia; Glendon, Gord; Mulligan, Anna M.; Dumont, Martine; Severi, Gianluca; Baglietto, Laura; Olson, Janet; Vachon, Celine; Purrington, Kristen; Moisse, Matthieu; Neven, Patrick; Wildiers, Hans; Spurdle, Amanda; Kosma, Veli-Matti; Kataja, Vesa; Hartikainen, Jaana M.; Hamann, Ute; Ko, Yon-Dschun; Dieffenbach, Aida K.; Arndt, Volker; Stegmaier, Christa; Malats, Núria; Arias Perez, JoséI.; Benítez, Javier; Flyger, Henrik; Nordestgaard, Børge G.; Truong, Théresè; Cordina-Duverger, Emilie; Menegaux, Florence; Silva, Isabel dos Santos; Fletcher, Olivia; Johnson, Nichola; Häberle, Lothar; Beckmann, Matthias W.; Ekici, Arif B.; Braaf, Linde; Atsma, Femke; van den Broek, Alexandra J.; Makalic, Enes; Schmidt, Daniel F.; Southey, Melissa C.; Cox, Angela; Simard, Jacques; Giles, Graham G.; Lambrechts, Diether; Mannermaa, Arto; Brauch, Hiltrud; Guénel, Pascal; Peto, Julian; Fasching, Peter A.; Hopper, John; Flesch-Janys, Dieter; Couch, Fergus; Chenevix-Trench, Georgia; Pharoah, Paul D. P.; Garcia-Closas, Montserrat; Schmidt, Marjanka K.; Hall, Per; Easton, Douglas F.; Chang-Claude, Jenny

    2014-01-01

    Genes that alter disease risk only in combination with certain environmental exposures may not be detected in genetic association analysis. By using methods accounting for gene-environment (G × E) interaction, we aimed to identify novel genetic loci associated with breast cancer risk. Up to 34,475 cases and 34,786 controls of European ancestry from up to 23 studies in the Breast Cancer Association Consortium were included. Overall, 71,527 single nucleotide polymorphisms (SNPs), enriched for association with breast cancer, were tested for interaction with 10 environmental risk factors using three recently proposed hybrid methods and a joint test of association and interaction. Analyses were adjusted for age, study, population stratification, and confounding factors as applicable. Three SNPs in two independent loci showed statistically significant association: SNPs rs10483028 and rs2242714 in perfect linkage disequilibrium on chromosome 21 and rs12197388 in ARID1B on chromosome 6. While rs12197388 was identified using the joint test with parity and with age at menarche (P-values = 3 × 10?07), the variants on chromosome 21 q22.12, which showed interaction with adult body mass index (BMI) in 8,891 postmenopausal women, were identified by all methods applied. SNP rs10483028 was associated with breast cancer in women with a BMI below 25 kg/m2 (OR = 1.26, 95% CI 1.15–1.38) but not in women with a BMI of 30 kg/m2 or higher (OR = 0.89, 95% CI 0.72–1.11, P for interaction = 3.2 × 10?05). Our findings confirm comparable power of the recent methods for detecting G × E interaction and the utility of using G × E interaction analyses to identify new susceptibility loci. PMID:24248812

  20. Cognitive impairment: an increasingly important complication of type 2 diabetes: the age, gene\\/environment susceptibility--Reykjavik study

    Microsoft Academic Search

    Jane S. Saczynski; Maria K. Jonsdottir; Melissa E. Garcia; Palmi V. Jonsson; Rita Peila; Gudny Eiriksdottir; Elin Olafsdottir; Tamara B. Harris; Vilmundur Gudnason; Lenore J. Launer

    2008-01-01

    Persons with type 2 diabetes are at increased risk of cognitive dysfunction. Less is known about which cognitive abilities are affected and how undiagnosed diabetes and impaired fasting glucose relate to cognitive performance. The authors explored this question using data from 1,917 nondemented men and women (average age = 76 years) in the population-based Age, Gene\\/Environment Susceptibility-Reykjavik Study (2002-2006). Glycemic

  1. Dissolution of passive zirconium in electrolyte solutions: The influence of the environment

    Microsoft Academic Search

    G. M. Florianovich; E. A. Larchenko

    1995-01-01

    The anodic behavior of passive zirconium in aqueous electrolyte solutions is studied by the radiometry technique in conjunction with a variety of electrochemical methods and Auger spectroscopy. The conclusion is made that, generally, there is no direct correlation between the composition of the passivating film on zirconium and the dissolution rate of passive zirconium. Water molecules act as a passivating

  2. 2D Raman correlation analysis of formation mechanism of passivating film on overcharged LiCoO2 electrode with additive system

    NASA Astrophysics Data System (ADS)

    Park, Yeonju; Shin, Su Hyun; Lee, Sung Man; Kim, Sung Phil; Choi, Hyun Chul; Jung, Young Mee

    2014-07-01

    The effect of vinylene carbonate (VC) as solid electrolyte interface (SEI)-forming additive on the electrochemical performance of the LiCoO2 cathode was investigated by galvanostatic charge-discharge testing as well as Raman and 2D correlation spectroscopy. It was found that VC-containing electrolyte has a positive effect on capacity fading. An analysis of the 2D Raman correlation spectra suggested that even though the same SEI components (i.e., Co3O4 and Li2O) are produced on the cathode surface, the electrochemical reaction kinetics in the cathode/electrolyte interface differ according to the non-use or use of VC: in the latter case, formation of the SEI components is delayed.

  3. Adaptive passive fathometer processing.

    PubMed

    Siderius, Martin; Song, Heechun; Gerstoft, Peter; Hodgkiss, William S; Hursky, Paul; Harrison, Chris

    2010-04-01

    Recently, a technique has been developed to image seabed layers using the ocean ambient noise field as the sound source. This so called passive fathometer technique exploits the naturally occurring acoustic sounds generated on the sea-surface, primarily from breaking waves. The method is based on the cross-correlation of noise from the ocean surface with its echo from the seabed, which recovers travel times to significant seabed reflectors. To limit averaging time and make this practical, beamforming is used with a vertical array of hydrophones to reduce interference from horizontally propagating noise. The initial development used conventional beamforming, but significant improvements have been realized using adaptive techniques. In this paper, adaptive methods for this process are described and applied to several data sets to demonstrate improvements possible as compared to conventional processing. PMID:20370000

  4. Interlanguage Passive Construction

    ERIC Educational Resources Information Center

    Simargool, Nirada

    2008-01-01

    Because the appearance of the passive construction varies cross linguistically, differences exist in the interlanguage (IL) passives attempted by learners of English. One such difference is the widely studied IL pseudo passive, as in "*new cars must keep inside" produced by Chinese speakers. The belief that this is a reflection of L1 language…

  5. Exploration of gene-environment interactions, maternal effects, and parent-of-origin effects in the etiology of hypospadias

    PubMed Central

    van der Zanden, Loes F.M.; Galesloot, Tessel E.; Feitz, Wout F.J.; Brouwers, Marijn M.; Shi, Min; Knoers, Nine V.A.M.; Franke, Barbara; Roeleveld, Nel; van Rooij, Iris A.L.M.

    2013-01-01

    Purpose Hypospadias is a common congenital malformation of the male external genitalia. Association studies for single nucleotide polymorphisms (SNPs) in genes encoding steroid-5-alpha-reductase (SRD5A2), estrogen receptors 1 (ESR1) and 2 (ESR2), and activating transcription factor 3 (ATF3) have been equivocal. The aim of this study was to examine whether non-replication of findings for four SNPs in these genes could be due to interaction with environmental exposures. Materials and Methods We genotyped 712 Dutch hypospadias case-parent triads for the four SNPs, used questionnaire information to determine exposures, and performed association tests using the log-linear approach. We studied gene-environment interactions for the four SNPs with exposure to estrogens, cytokines or cigarette smoke, multiple pregnancy, being born small for gestational age, and maternal hypertension or preeclampsia, high BMI, or primiparity. In addition, the presence of maternal genetic and parent-of-origin effects was tested. Results Gene-environment interactions were identified for rs523349 in SRD5A2 with estrogen exposure and maternal hypertension or preeclampsia, as well as for rs11119982 in ATF3 with exposure to cytokines. Both SNPs only seemed to influence hypospadias risk in exposed cases. For rs6932902 in ESR1, only maternally derived alleles appeared to increase hypospadias risk in offspring. Conclusions This study shows that interactions between genetic and environmental factors may help to explain non-replication in genetic studies of hypospadias. PMID:23088992

  6. Gene-environment interactions of CETP gene variation in a high cardiovascular risk Mediterranean population[S

    PubMed Central

    Corella, Dolores; Carrasco, Paula; Fitó, Montserrat; Martínez-González, Miguel Angel; Salas-Salvadó, Jordi; Arós, Fernando; Lapetra, José; Guillén, Marisa; Ortega-Azorín, Carolina; Warnberg, Julia; Fiol, Miquel; Ruiz-Gutierrez, Valentina; Serra-Majem, Lluís; Martínez, J. Alfredo; Ros, Emilio; Estruch, Ramón

    2010-01-01

    Genome-wide association studies show that cholesteryl ester transfer protein (CETP) single nucleotide polymorphisms (SNPs) are more strongly associated with HDL cholesterol (HDL-C) concentrations than any other loci across the genome. However, gene-environment interactions for clinical applications are still largely unknown. We studied gene-environment interactions between CETP SNPs and dietary fat intake, adherence to the Mediterranean diet, alcohol consumption, smoking, obesity, and diabetes on HDL-C in 4,210 high cardiovascular risk subjects from a Mediterranean population. We focused on the ?4,502C>T and the TaqIB SNPs in partial linkage disequilibrium (D'= 0.88; P < 0.001). They were independently associated with higher HDL-C (P < 0.001); this clinically relevant association was greater when their diplotype was considered (14% higher in TT/B2B2 vs. CC/B1B1). No gene-gene interaction was observed. We also analyzed the association of these SNPs with blood pressure, and no clinically relevant associations were detected. No statistically significant interactions of these SNPs with obesity, diabetes, and smoking in determining HDL-C concentrations were found. Likewise, alcohol, dietary fat, and adherence to the Mediterranean diet did not statistically interact with the CETP variants (independently or as diplotype) in determining HDL-C. In conclusion, the strong association of the CETP SNPs and HDL-C was not statistically modified by diet or by the other environmental factors. PMID:20581105

  7. Gene-environment interplay in Drosophila melanogaster: chronic nutritional deprivation in larval life affects adult fecal output.

    PubMed

    Urquhart-Cronish, Mackenzie; Sokolowski, Marla B

    2014-10-01

    Life history consequences of stress in early life are varied and known to have lasting impacts on the fitness of an organism. Gene-environment interactions play a large role in how phenotypic differences are mediated by stressful conditions during development. Here we use natural allelic 'rover/sitter' variants of the foraging (for) gene and chronic early life nutrient deprivation to investigate gene-environment interactions on excretion phenotypes. Excretion assay analysis and a fully factorial nutritional regimen encompassing the larval and adult life cycle of Drosophila melanogaster were used to assess the effects of larval and adult nutritional stress on adult excretion phenotypes. Natural allelic variants of for exhibited differences in the number of fecal spots when they were nutritionally deprived as larvae and well fed as adults. for mediates the excretion response to chronic early-life nutritional stress in mated female, virgin female, and male rovers and sitters. Transgenic manipulations of for in a sitter genetic background under larval but not adult food deprivation increases the number of fecal spots. Our study shows that food deprivation early in life affects adult excretion phenotypes and these excretion differences are mediated by for. PMID:24929224

  8. Passivity, complete passivity, and virtual temperatures

    NASA Astrophysics Data System (ADS)

    Skrzypczyk, Paul; Silva, Ralph; Brunner, Nicolas

    2015-05-01

    We give a simple and intuitive proof that the only states which are completely passive, i.e., those states from which work cannot be extracted even with infinitely many copies, are Gibbs states at positive temperatures. The proof makes use of the idea of virtual temperatures, i.e., the association of temperatures to pairs of energy levels (transitions). We show that (1) passive states are those where every transition is at a positive temperature and (2) completely passive states are those where every transition is at the same positive temperature.

  9. Localized photoelectrochemical measurements of passive films on titanium

    SciTech Connect

    Butler, M.A.

    1983-12-01

    Using a focused laser and a digitally controlled x-y stage, localized photoelectrochemical measurements have been made on 100A thick passive films on polycrystalline titanium. The photocurrent dependence on potential is semiquantitatively explained by a model considering trap dominated electronic charge transport in the passive film. Variations in the measured electronic properties are observed which correlate with the underlying metal grain structure. The data suggest extremely high trap densities in the passivating film.

  10. Gene–Environment Interplay Helps to Explain Influences of Family Relationships on Adolescent Adjustment and Development

    Microsoft Academic Search

    Jenae M. Neiderhiser

    \\u000a It is clear that the family relationships have important and lasting ­influences on adolescent adjustment and development.\\u000a Genetically informed ­studies have provided additional information suggesting that these influences are due, at least in part,\\u000a to the interplay of genetic and environmental factors via genotype–environment correlation and interaction. Understanding\\u000a the relative contributions of genes and environment and how they operate together

  11. Gene-environment interaction effects on lung function- a genome-wide association study within the Framingham heart study

    PubMed Central

    2013-01-01

    Background Previous studies in occupational exposure and lung function have focused only on the main effect of occupational exposure or genetics on lung function. Some disease-susceptible genes may be missed due to their low marginal effects, despite potential involvement in the disease process through interactions with the environment. Through comprehensive genome-wide gene-environment interaction studies, we can uncover these susceptibility genes. Our objective in this study was to explore gene by occupational exposure interaction effects on lung function using both the individual SNPs approach and the genetic network approach. Methods The study population comprised the Offspring Cohort and the Third Generation from the Framingham Heart Study. We used forced expiratory volume in one second (FEV1) and ratio of FEV1 to forced vital capacity (FVC) as outcomes. Occupational exposures were classified using a population-specific job exposure matrix. We performed genome-wide gene-environment interaction analysis, using the Affymetrix 550 K mapping array for genotyping. A linear regression-based generalized estimating equation was applied to account for within-family relatedness. Network analysis was conducted using results from single-nucleotide polymorphism (SNP)-level analyses and from gene expression study results. Results There were 4,785 participants in total. SNP-level analysis and network analysis identified SNP rs9931086 (Pinteraction =1.16 × 10-7) in gene SLC38A8, which may significantly modify the effects of occupational exposure on FEV1. Genes identified from the network analysis included CTLA-4, HDAC, and PPAR-alpha. Conclusions Our study implies that SNP rs9931086 in SLC38A8 and genes CTLA-4, HDAC, and PPAR-alpha, which are related to inflammatory processes, may modify the effect of occupational exposure on lung function. PMID:24289273

  12. Association of Environmental and Genetic Factors and Gene-Environment Interactions with Risk of Developing Rheumatoid Arthritis

    PubMed Central

    Karlson, Elizabeth W.; Ding, Bo; Keenan, Brendan T.; Liao, Katherine; Costenbader, Karen H.; Klareskog, Lars; Alfredsson, Lars; Chibnik, Lori B.

    2013-01-01

    Background We developed RA risk models based on validated environmental factors (E), genetic risk scores (GRS), and gene-environment interactions (GEI) to identify factors that can improve accuracy and reclassification. Methods Models including E, GRS, GEI were developed among 317 Caucasian seropositive RA cases and 551 controls from Nurses’ Health Studies (NHS) and validated in 987 Caucasian ACPA positive cases and 958 controls from the Swedish Epidemiologic Investigation of RA (EIRA), stratified by gender. Primary analyses included age, smoking, alcohol, parity, weighted GRS using 31 non-HLA alleles, 8 HLA-DRB1 alleles and HLA X smoking interaction. Expanded models included reproductive, geographic, and occupational factors, and additional GEI terms. Hierarchical models were compared for discriminative accuracy using AUC and reclassification using Integrated Discrimination Improvement (IDI) and continuous Net Reclassification Index. Results Mean (SD) age of RA diagnosis was 57 in NHS and 50 in EIRA. Primary models produced an AUC of 0.716 in NHS, 0.728 in EIRA women and 0.756 in EIRA men. Expanded models produced improvements in discrimination with AUCs of 0.738 in NHS, 0.728 in EIRA women and 0.769 in EIRA men. Models including G or G + GEI improved reclassification over E models; the full E+G+GEI model provided the optimal predictive ability by IDI analyses. Conclusions We have developed comprehensive RA risk models incorporating epidemiologic and genetic factors and gene-environment interactions that have improved discriminative accuracy for RA. Further work developing and assessing highly specific prediction models in prospective cohorts is still needed to inform primary RA prevention trials. PMID:23495093

  13. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Various Recipes of SiNx Passivated AlGaN\\/GaN High Electron Mobility Transistors in Correlation with Current Slump

    Microsoft Academic Search

    Ling Yang; Yue Hao; Xiao-Hua Ma; Si Quan; Gui-Zhou Hu; Shou-Gao Jiang; Li-Yuan Yang

    2009-01-01

    The current slump of different recipes of SiNx passivated AlGaN\\/GaN high electron mobility transistors (HEMTs) is investigated. The dc and pulsed current-voltage curves of AlGaN\\/GaN HEMTs using different recipes are analyzed. It is found that passivation leakage has a strong relationship with NH3 flow in the plasma-enhanced chemical vapor phase deposition process, which has impacted on the current collapse of

  14. Physics of passive solar buildings

    SciTech Connect

    Balcomb, J.D.

    1981-01-01

    Primary emphasis in the paper is on methods of characterizing and analyzing passive solar buildings. Simplifying assumptions are described which make this analysis tractable without compromising significant accuracy or loss of insight into the basic physics of the situation. The overall nature of the mathematical simulation approach is described. Validation procedures based on data from test rooms and monitored buildings are outlined. Issues of thermal comfort are discussed. Simplified methods of analysis based on correlation procedures are reported and the nature of the economic conservation-solar optimization process is explored. Future trends are predicted.

  15. Optimum mix of passive and active control of space structures

    NASA Technical Reports Server (NTRS)

    Rogers, Lynn; Richards, Ken

    1987-01-01

    The objective of this research was to test vibration suppression (settling time and jitter) of a large space structure (LSS) characterized by low frequency high global vibration modes. Five percent passive damping in a large truss was analyzed, tested and correlated. A representative system article re-target analysis shows that modest levels of passive damping dramatically reduce the control energy required. LSS must incorporate passive damping from the outset. The LSS system performance will not be met by either active or passive damping alone.

  16. Optimal Passive Source Localization

    Microsoft Academic Search

    Jan Neering; Marc Bordier; N. Maizi

    2007-01-01

    In order to optimize the estimation of an object's position, this paper proposes a procedure for placing acoustical sensors in 3D space, using passive source localization. A standard performance measure in estimation theory is the Cramer-Rao Lower Bound (CRLB), which describes the lower bound of the variance of unbiased estimators. In the case of passive source localization, this bound depends

  17. Chinese Passives: Transformational or Lexical?

    E-print Network

    Zhang, Jiuwu; Wen, Xiaohong

    1989-01-01

    There are two types of passive constructions in Chinese. Type I is a syntactic passive since it is derived through a transformational rule. Type II is a lexical passive. It has certain properties in common with the predicate ...

  18. How much can a large population study on genes, environments, their interactions and common diseases contribute to the health of the American people?

    Microsoft Academic Search

    Claudia Chaufan

    2007-01-01

    I offer a critical perspective on a large-scale population study on gene–environment interactions and common diseases proposed by the US Secretary of Health and Human Services’ Advisory Committee on Genetics, Health, and Society (SACGHS). I argue that for scientific and policy reasons this and similar studies have little to add to current knowledge about how to prevent, treat, or decrease

  19. Passive solar construction handbook

    SciTech Connect

    Levy, E.; Evans, D.; Gardstein, C.

    1981-08-01

    Many of the basic elements of passive solar design are reviewed. The unique design constraints presented in passive homes are introduced and many of the salient issues influencing design decisions are described briefly. Passive solar construction is described for each passive system type: direct gain, thermal storage wall, attached sunspace, thermal storage roof, and convective loop. For each system type, important design and construction issues are discussed and case studies illustrating designed and built examples of the system type are presented. Construction details are given and construction and thermal performance information is given for the materials used in collector components, storage components, and control components. Included are glazing materials, framing systems, caulking and sealants, concrete masonry, concrete, brick, shading, reflectors, and insulators. The Load Collector Ratio method for estimating passive system performance is appended, and other analysis methods are briefly summarized. (LEW)

  20. Role of gene-gene/gene-environment interaction in the etiology of eastern Indian ADHD probands.

    PubMed

    Das, Manali; Das Bhowmik, Aneek; Bhaduri, Nipa; Sarkar, Kanyakumarika; Ghosh, Paramita; Sinha, Swagata; Ray, Anirban; Chatterjee, Anindita; Mukhopadhyay, Kanchan

    2011-03-30

    Associations between attention deficit hyperactivity disorder (ADHD) and genetic polymorphisms in the dopamine receptors, transporter and metabolizing enzymes have been reported in different ethnic groups. Gene variants may affect disease outcome by acting synergistically or antagonistically and thus their combined effect becomes an important aspect to study in the disease etiology. In the present investigation, interaction between ten functional polymorphisms in DRD4, DAT1, MAOA, COMT, and DBH genes were explored in the Indo-Caucasoid population. ADHD cases were recruited based on DSM-IV criteria. Peripheral blood samples were collected from ADHD probands (N=126), their parents (N=233) and controls (N=96) after obtaining informed written consent for participation. Genomic DNA was subjected to PCR based analysis of single nucleotide polymorphisms and variable number of tandem repeats (VNTRs). Data obtained was examined for population as well as family-based association analyses. While case-control analysis revealed higher occurrence of DAT1 intron 8 VNTR 5R allele (P=0.02) in cases, significant preferential transmission of the 7R-T (DRD4 exon3 VNTR-rs1800955) and 3R-T (MAOA-u VNTR-rs6323) haplotypes were noticed from parents to probands (P=0.02 and 0.002 respectively). Gene-gene interaction analysis revealed significant additive effect of DBH rs1108580 and DRD4 rs1800955 with significant main effects of DRD4 exon3 VNTR, DAT1 3'UTR and intron 8 VNTR, MAOA u-VNTR, rs6323, COMT rs4680, rs362204, DBH rs1611115 and rs1108580 thereby pointing towards a strong association of these markers with ADHD. Correlation between gene variants, high ADHD score and low DBH enzymatic activity was also noticed, especially in male probands. From these observations, an impact of the studied sites on the disease etiology could be speculated in this ethnic group. PMID:21216270

  1. Evidence of Gene–Environment Interactions between Common Breast Cancer Susceptibility Loci and Established Environmental Risk Factors

    PubMed Central

    Nickels, Stefan; Truong, Thérèse; Hein, Rebecca; Stevens, Kristen; Buck, Katharina; Behrens, Sabine; Eilber, Ursula; Schmidt, Martina; Häberle, Lothar; Vrieling, Alina; Gaudet, Mia; Figueroa, Jonine; Schoof, Nils; Spurdle, Amanda B.; Rudolph, Anja; Fasching, Peter A.; Hopper, John L.; Makalic, Enes; Schmidt, Daniel F.; Southey, Melissa C.; Beckmann, Matthias W.; Ekici, Arif B.; Fletcher, Olivia; Gibson, Lorna; dos Santos Silva, Isabel; Peto, Julian; Humphreys, Manjeet K.; Wang, Jean; Cordina-Duverger, Emilie; Menegaux, Florence; Nordestgaard, Børge G.; Bojesen, Stig E.; Lanng, Charlotte; Anton-Culver, Hoda; Ziogas, Argyrios; Bernstein, Leslie; Clarke, Christina A.; Brenner, Hermann; Müller, Heiko; Arndt, Volker; Stegmaier, Christa; Brauch, Hiltrud; Brüning, Thomas; Harth, Volker; The GENICA Network; Mannermaa, Arto; Kataja, Vesa; Kosma, Veli-Matti; Hartikainen, Jaana M.; kConFab; Group, AOCS Management; Lambrechts, Diether; Smeets, Dominiek; Neven, Patrick; Paridaens, Robert; Flesch-Janys, Dieter; Obi, Nadia; Wang-Gohrke, Shan; Couch, Fergus J.; Olson, Janet E.; Vachon, Celine M.; Giles, Graham G.; Severi, Gianluca; Baglietto, Laura; Offit, Kenneth; John, Esther M.; Miron, Alexander; Andrulis, Irene L.; Knight, Julia A.; Glendon, Gord; Mulligan, Anna Marie; Chanock, Stephen J.; Lissowska, Jolanta; Liu, Jianjun; Cox, Angela; Cramp, Helen; Connley, Dan; Balasubramanian, Sabapathy; Dunning, Alison M.; Shah, Mitul; Trentham-Dietz, Amy; Newcomb, Polly; Titus, Linda; Egan, Kathleen; Cahoon, Elizabeth K.; Rajaraman, Preetha; Sigurdson, Alice J.; Doody, Michele M.; Guénel, Pascal; Pharoah, Paul D. P.; Schmidt, Marjanka K.; Hall, Per; Easton, Doug F.; Garcia-Closas, Montserrat; Milne, Roger L.; Chang-Claude, Jenny

    2013-01-01

    Various common genetic susceptibility loci have been identified for breast cancer; however, it is unclear how they combine with lifestyle/environmental risk factors to influence risk. We undertook an international collaborative study to assess gene-environment interaction for risk of breast cancer. Data from 24 studies of the Breast Cancer Association Consortium were pooled. Using up to 34,793 invasive breast cancers and 41,099 controls, we examined whether the relative risks associated with 23 single nucleotide polymorphisms were modified by 10 established environmental risk factors (age at menarche, parity, breastfeeding, body mass index, height, oral contraceptive use, menopausal hormone therapy use, alcohol consumption, cigarette smoking, physical activity) in women of European ancestry. We used logistic regression models stratified by study and adjusted for age and performed likelihood ratio tests to assess gene–environment interactions. All statistical tests were two-sided. We replicated previously reported potential interactions between LSP1-rs3817198 and parity (Pinteraction?=?2.4×10?6) and between CASP8-rs17468277 and alcohol consumption (Pinteraction?=?3.1×10?4). Overall, the per-allele odds ratio (95% confidence interval) for LSP1-rs3817198 was 1.08 (1.01–1.16) in nulliparous women and ranged from 1.03 (0.96–1.10) in parous women with one birth to 1.26 (1.16–1.37) in women with at least four births. For CASP8-rs17468277, the per-allele OR was 0.91 (0.85–0.98) in those with an alcohol intake of <20 g/day and 1.45 (1.14–1.85) in those who drank ?20 g/day. Additionally, interaction was found between 1p11.2-rs11249433 and ever being parous (Pinteraction?=?5.3×10?5), with a per-allele OR of 1.14 (1.11–1.17) in parous women and 0.98 (0.92–1.05) in nulliparous women. These data provide first strong evidence that the risk of breast cancer associated with some common genetic variants may vary with environmental risk factors. PMID:23544014

  2. ACR-1000 Passive Features

    SciTech Connect

    Lekakh, Boris; Hau, Ken; Ford, Steven [Atomic Energy of Canada Ltd. (Canada)

    2006-07-01

    The Advanced CANDU Reactor{sup TM} (ACR{sup TM}) is a Generation III+ pressure tube type reactor using light water coolant and heavy water moderator. The ACR-1000 reactor design is an evolutionary extension of the proven CANDU reactor design. The ACR-1000 incorporates multiple and diverse passive systems for accident mitigation. Where necessary, one or more features that are passive in nature have been included for mitigation of any postulated accident event. This paper describes how the use of passive design elements complements active features enhances reliability and improves safety margins. (authors)

  3. Gene-environment interplay in Drosophila melanogaster: chronic food deprivation in early life affects adult exploratory and fitness traits.

    PubMed

    Burns, James Geoffrey; Svetec, Nicolas; Rowe, Locke; Mery, Frederic; Dolan, Michael J; Boyce, W Thomas; Sokolowski, Marla B

    2012-10-16

    Early life adversity has known impacts on adult health and behavior, yet little is known about the gene-environment interactions (GEIs) that underlie these consequences. We used the fruit fly Drosophila melanogaster to show that chronic early nutritional adversity interacts with rover and sitter allelic variants of foraging (for) to affect adult exploratory behavior, a phenotype that is critical for foraging, and reproductive fitness. Chronic nutritional adversity during adulthood did not affect rover or sitter adult exploratory behavior; however, early nutritional adversity in the larval period increased sitter but not rover adult exploratory behavior. Increasing for gene expression in the mushroom bodies, an important center of integration in the fly brain, changed the amount of exploratory behavior exhibited by sitter adults when they did not experience early nutritional adversity but had no effect in sitters that experienced early nutritional adversity. Manipulation of the larval nutritional environment also affected adult reproductive output of sitters but not rovers, indicating GEIs on fitness itself. The natural for variants are an excellent model to examine how GEIs underlie the biological embedding of early experience. PMID:23045644

  4. Gene–environment interplay in Drosophila melanogaster: Chronic food deprivation in early life affects adult exploratory and fitness traits

    PubMed Central

    Burns, James Geoffrey; Svetec, Nicolas; Rowe, Locke; Mery, Frederic; Dolan, Michael J.; Boyce, W. Thomas; Sokolowski, Marla B.

    2012-01-01

    Early life adversity has known impacts on adult health and behavior, yet little is known about the gene–environment interactions (GEIs) that underlie these consequences. We used the fruit fly Drosophila melanogaster to show that chronic early nutritional adversity interacts with rover and sitter allelic variants of foraging (for) to affect adult exploratory behavior, a phenotype that is critical for foraging, and reproductive fitness. Chronic nutritional adversity during adulthood did not affect rover or sitter adult exploratory behavior; however, early nutritional adversity in the larval period increased sitter but not rover adult exploratory behavior. Increasing for gene expression in the mushroom bodies, an important center of integration in the fly brain, changed the amount of exploratory behavior exhibited by sitter adults when they did not experience early nutritional adversity but had no effect in sitters that experienced early nutritional adversity. Manipulation of the larval nutritional environment also affected adult reproductive output of sitters but not rovers, indicating GEIs on fitness itself. The natural for variants are an excellent model to examine how GEIs underlie the biological embedding of early experience. PMID:23045644

  5. Gene-environment interactions across development: Exploring DRD2 genotype and prenatal smoking effects on self-regulation.

    PubMed

    Wiebe, Sandra A; Espy, Kimberly Andrews; Stopp, Christian; Respass, Jennifer; Stewart, Peter; Jameson, Travis R; Gilbert, David G; Huggenvik, Jodi I

    2009-01-01

    Genetic factors dynamically interact with both pre- and postnatal environmental influences to shape development. Considerable attention has been devoted to gene-environment interactions (G x E) on important outcomes (A. Caspi & T. E. Moffitt, 2006). It is also important to consider the possibility that these G x E effects may vary across development, particularly for constructs like self-regulation that emerge slowly, depend on brain regions that change qualitatively in different developmental periods, and thus may be manifested differently. To illustrate one approach to exploring such developmental patterns, the relation between variation in the TaqIA polymorphism, related to D2 dopamine receptor expression and availability, and prenatal exposure to tobacco was examined in two exploratory studies. First, in 4-week-old neonates, genotype-exposure interactions were observed for attention and irritable reactivity, but not for stress dysregulation. Second, in preschool children, genotype was related to Preschool Trail Making Test (K. A. Espy and M. F. Cwik, 2004) task performance on conditions requiring executive control; children with both the A1+ genotype and a history of prenatal tobacco exposure displayed disproportionately poor performance. Despite study limitations, these results illustrate the importance of examining the interplay between genetic and prenatal environmental factors across development. PMID:19209988

  6. Gender-specific gene-environment interaction in alcohol dependence: the impact of daily life events and GABRA2.

    PubMed

    Perry, Brea L; Pescosolido, Bernice A; Bucholz, Kathleen; Edenberg, Howard; Kramer, John; Kuperman, Samuel; Schuckit, Marc Alan; Nurnberger, John I

    2013-09-01

    Gender-moderated gene-environment interactions are rarely explored, raising concerns about inaccurate specification of etiological models and inferential errors. The current study examined the influence of gender, negative and positive daily life events, and GABRA2 genotype (SNP rs279871) on alcohol dependence, testing two- and three-way interactions between these variables using multi-level regression models fit to data from 2,281 White participants in the Collaborative Study on the Genetics of Alcoholism. Significant direct effects of variables of interest were identified, as well as gender-specific moderation of genetic risk on this SNP by social experiences. Higher levels of positive life events were protective for men with the high-risk genotype, but not among men with the low-risk genotype or women, regardless of genotype. Our findings support the disinhibition theory of alcohol dependence, suggesting that gender differences in social norms, constraints and opportunities, and behavioral undercontrol may explain men and women's distinct patterns of association. PMID:23974430

  7. Chronic and Acute Stress, Gender, and Serotonin Transporter Gene-Environment Interactions Predicting Depression Symptoms in Youth

    PubMed Central

    Hammen, Constance; Brennan, Patricia A.; Keenan-Miller, Danielle; Hazel, Nicholas A.; Najman, Jake M.

    2010-01-01

    Background Many recent studies of serotonin transporter gene by environment effects predicting depression have used stress assessments with undefined or poor psychometric methods, possibly contributing to wide variation in findings. The present study attempted to distinguish between effects of acute and chronic stress to predict depressive symptoms at age 20 among 346 youth varying in polymorphisms of the 5HTT gene who had been assessed at ages 15 and 20. Methods Interview measures assessed major acute life events between 15 and 19, and multiple interviews and questionnaires with youths and their parents at youth age 15 provided an index of chronic family stress. Lg alleles were reclassified as S. Results Chronic family stress at age 15 predicted higher depression scores at 20 among those with one or two S alleles, and the effects of genetic moderation were significant only for females. Gene-environment interactions with acute stress were nonsignificant. Conclusions Careful measurement and separation of the effects of chronic and acute stress, and gender, are encouraged in the study of mechanisms of the stress-depression association. PMID:19811586

  8. Gene-gene, gene-environment, gene-nutrient interactions and single nucleotide polymorphisms of inflammatory cytokines.

    PubMed

    Nadeem, Amina; Mumtaz, Sadaf; Naveed, Abdul Khaliq; Aslam, Muhammad; Siddiqui, Arif; Lodhi, Ghulam Mustafa; Ahmad, Tausif

    2015-05-15

    Inflammation plays a significant role in the etiology of type 2 diabetes mellitus (T2DM). The rise in the pro-inflammatory cytokines is the essential step in glucotoxicity and lipotoxicity induced mitochondrial injury, oxidative stress and beta cell apoptosis in T2DM. Among the recognized markers are interleukin (IL)-6, IL-1, IL-10, IL-18, tissue necrosis factor-alpha (TNF-?), C-reactive protein, resistin, adiponectin, tissue plasminogen activator, fibrinogen and heptoglobins. Diabetes mellitus has firm genetic and very strong environmental influence; exhibiting a polygenic mode of inheritance. Many single nucleotide polymorphisms (SNPs) in various genes including those of pro and anti-inflammatory cytokines have been reported as a risk for T2DM. Not all the SNPs have been confirmed by unifying results in different studies and wide variations have been reported in various ethnic groups. The inter-ethnic variations can be explained by the fact that gene expression may be regulated by gene-gene, gene-environment and gene-nutrient interactions. This review highlights the impact of these interactions on determining the role of single nucleotide polymorphism of IL-6, TNF-?, resistin and adiponectin in pathogenesis of T2DM. PMID:25987962

  9. Assessing gene-environment interactions for common and rare variants with binary traits using gene-trait similarity regression.

    PubMed

    Zhao, Guolin; Marceau, Rachel; Zhang, Daowen; Tzeng, Jung-Ying

    2015-03-01

    Accounting for gene-environment (G×E) interactions in complex trait association studies can facilitate our understanding of genetic heterogeneity under different environmental exposures, improve the ability to discover susceptible genes that exhibit little marginal effect, provide insight into the biological mechanisms of complex diseases, help to identify high-risk subgroups in the population, and uncover hidden heritability. However, significant G×E interactions can be difficult to find. The sample sizes required for sufficient power to detect association are much larger than those needed for genetic main effects, and interactions are sensitive to misspecification of the main-effects model. These issues are exacerbated when working with binary phenotypes and rare variants, which bear less information on association. In this work, we present a similarity-based regression method for evaluating G×E interactions for rare variants with binary traits. The proposed model aggregates the genetic and G×E information across markers, using genetic similarity, thus increasing the ability to detect G×E signals. The model has a random effects interpretation, which leads to robustness against main-effect misspecifications when evaluating G×E interactions. We construct score tests to examine G×E interactions and a computationally efficient EM algorithm to estimate the nuisance variance components. Using simulations and data applications, we show that the proposed method is a flexible and powerful tool to study the G×E effect in common or rare variant studies with binary traits. PMID:25585620

  10. Passive microfluidic interconnects

    E-print Network

    Jonnalagadda, Aparna S

    2005-01-01

    Equipment and procedures were developed to test two passive microfluidic interconnect rings held together by the friction forces on the contact surfaces. The second design forms fluid seals by means of thin flared rings ...

  11. Acquisition of the Passive

    E-print Network

    Hill, Francine

    1998-01-01

    This single-subject pilot study, modeled after de Villiers' 1973, investigates the subject's acquisition of the passive construction (i.e., 'The boy was hit by the girl', as opposed to The girl hit the boy'). The purposes ...

  12. Hood River Passive House

    SciTech Connect

    Hales, D.

    2013-03-01

    The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to reduce home energy use by 30%-50% (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift House and compares the results of PHPP and BEopt modeling of the project.

  13. I Just Ran a Thousand Analyses: Benefits of Multiple Testing in Understanding Equivocal Evidence on Gene-Environment Interactions

    PubMed Central

    Heininga, Vera E.; Oldehinkel, Albertine J.; Veenstra, René; Nederhof, Esther

    2015-01-01

    Background In psychiatric genetics research, the volume of ambivalent findings on gene-environment interactions (G x E) is growing at an accelerating pace. In response to the surging suspicions of systematic distortion, we challenge the notion of chance capitalization as a possible contributor. Beyond qualifying multiple testing as a mere methodological issue that, if uncorrected, leads to chance capitalization, we advance towards illustrating the potential benefits of multiple tests in understanding equivocal evidence in genetics literature. Method We focused on the interaction between the serotonin-transporter-linked promotor region (5-HTTLPR) and childhood adversities with regard to depression. After testing 2160 interactions with all relevant measures available within the Dutch population study of adolescents TRAILS, we calculated percentages of significant (p < .05) effects for several subsets of regressions. Using chance capitalization (i.e. overall significance rate of 5% alpha and randomly distributed findings) as a competing hypothesis, we expected more significant effects in the subsets of regressions involving: 1) interview-based instead of questionnaire-based measures; 2) abuse instead of milder childhood adversities; and 3) early instead of later adversities. Furthermore, we expected equal significance percentages across 4) male and female subsamples, and 5) various genotypic models of 5-HTTLPR. Results We found differences in the percentages of significant interactions among the subsets of analyses, including those regarding sex-specific subsamples and genetic modeling, but often in unexpected directions. Overall, the percentage of significant interactions was 7.9% which is only slightly above the 5% that might be expected based on chance. Conclusion Taken together, multiple testing provides a novel approach to better understand equivocal evidence on G x E, showing that methodological differences across studies are a likely reason for heterogeneity in findings - but chance capitalization is at least equally plausible. PMID:26016887

  14. Meta-analysis of Gene-Environment interaction: joint estimation of SNP and SNP×Environment regression coefficients

    PubMed Central

    Manning, Alisa K.; LaValley, Michael; Liu, Ching-Ti; Rice, Ken; An, Ping; Liu, Yongmei; Miljkovic, Iva; Rasmussen-Torvik, Laura; Harris, Tamara B.; Province, Michael A.; Borecki, Ingrid B.; Florez, Jose C.; Meigs, James B.; Cupples, L. Adrienne; Dupuis, Josée

    2012-01-01

    Introduction Genetic discoveries are validated through the meta-analysis of genome-wide association scans in large international consortia. Because environmental variables may interact with genetic factors, investigation of differing genetic effects for distinct levels of an environmental exposure in these large consortia may yield additional susceptibility loci undetected by main effects analysis. We describe a method of joint meta-analysis of SNP and SNP by Environment (SNP×E) regression coefficients for use in gene-environment interaction studies. Methods In testing SNP×E interactions, one approach uses a two degree of freedom test to identify genetic variants that influence the trait of interest. This approach detects both main and interaction effects between the trait and the SNP. We propose a method to jointly meta-analyze the SNP and SNP×E coefficients using multivariate generalized least squares. This approach provides confidence intervals of the two estimates, a joint significance test for SNP and SNP×E terms, and a test of homogeneity across samples. Results We present a simulation study comparing this method to four other methods of meta-analysis and demonstrate that the joint meta-analysis performs better than the others when both main and interaction effects are present. Additionally, we implemented our methods in a meta-analysis of the association between SNPs from the type 2 diabetes-associated gene PPARG and log-transformed fasting insulin levels and interaction by body mass index in a combined sample of 19,466 individuals from 5 cohorts. PMID:21181894

  15. Gene–environment interaction in externalizing problems among adolescents: evidence from the Pelotas 1993 Birth Cohort Study

    PubMed Central

    Kieling, Christian; Hutz, Mara H; Genro, Júlia P; Polanczyk, Guilherme V; Anselmi, Luciana; Camey, Suzi; Hallal, Pedro C; Barros, Fernando C; Victora, Cesar G; Menezes, Ana M B; Rohde, Luis Augusto

    2013-01-01

    Background The study of gene–environment interactions (G × E) is one of the most promising strategies to uncover the origins of mental disorders. Replication of initial findings, however, is essential because there is a strong possibility of publication bias in the literature. In addition, there is a scarcity of research on the topic originated from low- and middle-income countries (LMIC). The aim of this study was to replicate G × E hypotheses for externalizing problems among adolescents in a middle-income country. Methods As part of the Pelotas 1993 Birth Cohort Study, 5,249 children were enrolled at birth and followed up to the age of 15 years, with an 85.7% retention rate. We sought an interaction between the homozygosity of the 10-repeat allele at the dopamine transporter (DAT1) gene and prenatal maternal smoking in the development of hyperactivity problems during adolescence assessed by the Strengths and Difficulties Questionnaire. We also tested for an interaction between the uVNTR polymorphism at the monoamine oxidase A (MAOA) and the experience of childhood maltreatment in the occurrence of conduct problems among adolescent boys. Results Although there was a clear association between prenatal maternal smoking and hyperactivity scores in adolescence (p < 0.001), no main genetic or interaction effects for the DAT1 gene were detected. Similarly, childhood maltreatment showed to be associated with conduct problems among boys (p < 0.001), with no observable main genetic or interaction effects for the MAOA gene. Conclusions In the largest mental health G × E study performed in a LMIC to date, we did not replicate previous positive findings from the literature. Despite the presence of main environmental effects, there was no evidence of effect modification by genotype status. Additional replication efforts to measure G × E are needed to better understand the origins of mental health and illness, especially in LMIC. PMID:23215821

  16. Gene-environment interactions between JAZF1 and occupational and household lead exposure in prostate cancer among African American men

    PubMed Central

    Neslund-Dudas, Christine; Levin, Albert M.; Beebe-Dimmer, Jennifer L.; Bock, Cathryn H.; Nock, Nora L.; Rundle, Andrew; Jankowski, Michelle; Krajenta, Richard; Dou, Q. Ping; Mitra, Bharati; Tang, Deliang; Rebbeck, Timothy R.; Rybicki, Benjamin A.

    2014-01-01

    Purpose A single nucleotide polymorphism, rs10486567, in JAZF1 has consistently been associated with increased risk of prostate cancer. The physical interaction of zinc finger proteins, such as JAZF1, with heavy metals may play a role in carcinogenesis. This study assessed potential gene-environment statistical interactions (GxE) between rs10486567 and heavy metals in prostate cancer. Methods In a case-only study of 228 African American prostate cancer cases, GxE between rs10486567 and sources of cadmium (Cd) and lead (Pb) were assessed. Unconditional logistic regression was used to estimate interaction odds ratios and GEE was used for models containing nested data. Case-control validation of IORs was performed, using 82 controls frequency matched to cases on age-race. Results Among cases, a potential GxE interaction was observed between rs10486567 CC genotype and living in a Census tract with a high proportion of housing built before 1950, a proxy for household Pb exposure, when compared to CT or TT carriers (OR 1.81; 95% CI 1.04-3.16; p=0.036). A stronger GxE interaction was observed when both housing and occupational Pb exposure were taken into account (OR 2.62; 95% CI 1.03-6.68; p=0.04). Case-control stratified analyses showed the odds of being a CC carrier was higher in cases compared to controls among men living in areas with older housing (OR 2.03; CI 0.99-4.19; p=0.05) or having high occupational Pb exposure (OR 2.50; CI 1.01-6.18; p=0.05). Conclusions In African American men, the association between JAZF1 rs10486567 and prostate cancer may be modified by exposure to heavy metals such as Pb. PMID:24801046

  17. Case-Only Gene–Environment Interaction Between ALAD tagSNPs and Occupational Lead Exposure in Prostate Cancer

    PubMed Central

    Neslund-Dudas, Christine; Levin, Albert M.; Rundle, Andrew; Beebe-Dimmer, Jennifer; Bock, Cathryn H.; Nock, Nora L.; Jankowski, Michelle; Datta, Indrani; Krajenta, Richard; Dou, Q. Ping; Mitra, Bharati; Tang, Deliang; Rybicki, Benjamin A.

    2014-01-01

    BACKGROUND Black men have historically had higher blood lead levels than white men in the U.S. and have the highest incidence of prostate cancer in the world. Inorganic lead has been classified as a probable human carcinogen. Lead (Pb) inhibits delta-aminolevulinic acid dehydratase (ALAD), a gene recently implicated in other genitourinary cancers. The ALAD enzyme is involved in the second step of heme biosynthesis and is an endogenous inhibitor of the 26S proteasome, a master system for protein degradation and a current target of cancer therapy. METHODS Using a case-only study design, we assessed potential gene–environment (G × E) interactions between lifetime occupational Pb exposure and 11 tagSNPs within ALAD in black (N = 260) and white (N = 343) prostate cancer cases. RESULTS Two ALAD tagSNPs in high linkage disequilibrium showed significant interaction with high Pb exposure among black cases (rs818684 interaction odds ratio or IOR = 2.73, 95% CI 1.43–5.22, P = 0.002; rs818689 IOR = 2.20, 95% CI 1.15–4.21, P = 0.017) and an additional tagSNP, rs2761016, showed G × E interaction with low Pb exposure (IOR = 2.08, 95% CI 1.13– 3.84, P = 0.019). Further, the variant allele of rs818684 was associated with a higher Gleason grade in those with high Pb exposure among both blacks (OR 3.96, 95% CI 1.01–15.46, P = 0.048) and whites (OR 2.95, 95% CI 1.18–7.39, P = 0.020). CONCLUSIONS Genetic variation in ALAD may modify associations between Pb and prostate cancer. Additional studies of ALAD, Pb, and prostate cancer are warranted and should include black men. PMID:24500903

  18. Epigenetic Genes and Emotional Reactivity to Daily Life Events: A Multi-Step Gene-Environment Interaction Study

    PubMed Central

    Pishva, Ehsan; Drukker, Marjan; Viechtbauer, Wolfgang; Decoster, Jeroen; Collip, Dina; van Winkel, Ruud; Wichers, Marieke; Jacobs, Nele; Thiery, Evert; Derom, Catherine; Geschwind, Nicole; van den Hove, Daniel; Lataster, Tineke; Myin-Germeys, Inez; van Os, Jim

    2014-01-01

    Recent human and animal studies suggest that epigenetic mechanisms mediate the impact of environment on development of mental disorders. Therefore, we hypothesized that polymorphisms in epigenetic-regulatory genes impact stress-induced emotional changes. A multi-step, multi-sample gene-environment interaction analysis was conducted to test whether 31 single nucleotide polymorphisms (SNPs) in epigenetic-regulatory genes, i.e. three DNA methyltransferase genes DNMT1, DNMT3A, DNMT3B, and methylenetetrahydrofolate reductase (MTHFR), moderate emotional responses to stressful and pleasant stimuli in daily life as measured by Experience Sampling Methodology (ESM). In the first step, main and interactive effects were tested in a sample of 112 healthy individuals. Significant associations in this discovery sample were then investigated in a population-based sample of 434 individuals for replication. SNPs showing significant effects in both the discovery and replication samples were subsequently tested in three other samples of: (i) 85 unaffected siblings of patients with psychosis, (ii) 110 patients with psychotic disorders, and iii) 126 patients with a history of major depressive disorder. Multilevel linear regression analyses showed no significant association between SNPs and negative affect or positive affect. No SNPs moderated the effect of pleasant stimuli on positive affect. Three SNPs of DNMT3A (rs11683424, rs1465764, rs1465825) and 1 SNP of MTHFR (rs1801131) moderated the effect of stressful events on negative affect. Only rs11683424 of DNMT3A showed consistent directions of effect in the majority of the 5 samples. These data provide the first evidence that emotional responses to daily life stressors may be moderated by genetic variation in the genes involved in the epigenetic machinery. PMID:24967710

  19. Powerful Tukey’s One Degree-of-Freedom Test for Detecting Gene–Gene and Gene–Environment Interactions

    PubMed Central

    Wang, Yaping; Li, Donghui; Wei, Peng

    2015-01-01

    Genome-wide association studies (GWASs) have identified thousands of single nucleotide polymorphisms (SNPs) robustly associated with hundreds of complex human diseases including cancers. However, the large number of GWAS-identified genetic loci only explains a small proportion of the disease heritability. This “missing heritability” problem has been partly attributed to the yet-to-be-identified gene–gene (G × G) and gene–environment (G × E) interactions. In spite of the important roles of G × G and G × E interactions in understanding disease mechanisms and filling in the missing heritability, straightforward GWAS scanning for such interactions has very limited statistical power, leading to few successes. Here we propose a two-step statistical approach to test G × G/G × E interactions: the first step is to perform principal component analysis (PCA) on the multiple SNPs within a gene region, and the second step is to perform Tukey’s one degree-of-freedom (1-df) test on the leading PCs. We derive a score test that is computationally fast and numerically stable for the proposed Tukey’s 1-df interaction test. Using extensive simulations we show that the proposed approach, which combines the two parsimonious models, namely, the PCA and Tukey’s 1-df form of interaction, outperforms other state-of-the-art methods. We also demonstrate the utility and efficiency gains of the proposed method with applications to testing G × G interactions for Crohn’s disease using the Wellcome Trust Case Control Consortium (WTCCC) GWAS data and testing G × E interaction using data from a case–control study of pancreatic cancer.

  20. Wireless passive radiation sensor

    DOEpatents

    Pfeifer, Kent B; Rumpf, Arthur N; Yelton, William G; Limmer, Steven J

    2013-12-03

    A novel measurement technique is employed using surface acoustic wave (SAW) devices, passive RF, and radiation-sensitive films to provide a wireless passive radiation sensor that requires no batteries, outside wiring, or regular maintenance. The sensor is small (<1 cm.sup.2), physically robust, and will operate unattended for decades. In addition, the sensor can be insensitive to measurement position and read distance due to a novel self-referencing technique eliminating the need to measure absolute responses that are dependent on RF transmitter location and power.

  1. Passive in vivo elastography from skeletal muscle noise

    SciTech Connect

    Sabra, Karim G.; Conti, Stephane; Roux, Philippe; Kuperman, W. A. [Marine Physical Laboratory, Scripps Institution of Oceanography, University of California San Diego, San Diego, California 92093-0238 (United States)

    2007-05-07

    Measuring the in vivo elastic properties of muscles (e.g., stiffness) provides a means for diagnosing and monitoring muscular activity. The authors demonstrated a passive in vivo elastography technique without an active external radiation source. This technique instead uses cross correlations of contracting skeletal muscle noise recorded with skin-mounted sensors. Each passive sensor becomes a virtual in vivo shear wave source. The results point to a low-cost, noninvasive technique for monitoring biomechanical in vivo muscle properties. The efficacy of the passive elastography technique originates from the high density of cross paths between all sensor pairs, potentially achieving the same sensitivity obtained from active elastography methods.

  2. Moving to passive designs

    Microsoft Academic Search

    Robert Rosner; Rebecca Lordan; Stephen Goldberg

    2011-01-01

    The events at Fukushima Daiichi have greatly renewed the public focus on the safety of the existing fleet of nuclear reactors, especially as many US reactors share the same fundamental design—and safety systems—as the affected Japanese reactors. The authors explore the proposition that a transition to increasingly passive safety features in new advanced reactor designs— supplementing, and in some cases

  3. Passive Dynamic Running

    Microsoft Academic Search

    Clay M. Thompson; Marc H. Raiber

    1989-01-01

    Previous work has considered how springy legs can improve the efficiency of the vertical motions of running, making them into resonant spring-mass oscillations that recycle energy from one step to the next. This paper considers how springy hips can be used to improve the efficiency of the legs' fore and aft swinging motions in running. We have studied a passive

  4. Hood River Passive House

    SciTech Connect

    Hales, D.

    2014-01-01

    The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to reduce home energy use by 30%-50% (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift House and compares the results of PHPP and BEopt modeling of the project. The design includes high R-Value assemblies, extremely tight construction, high performance doors and windows, solar thermal DHW, heat recovery ventilation, moveable external shutters and a high performance ductless mini-split heat pump. Cost analysis indicates that many of the measures implemented in this project did not meet the BA standard for cost neutrality. The ductless mini-split heat pump, lighting and advanced air leakage control were the most cost effective measures. The future challenge will be to value engineer the performance levels indicated here in modeling using production based practices at a significantly lower cost.

  5. Novel passive thermal mixer

    Microsoft Academic Search

    Stephen A. Idem; Sastry S. Munukutla

    1991-01-01

    A passive thermal mixer concept is proposed for improvement of the thermal performance of a heating tank containing heating elements attached to the top lid. The element is enclosed by a cylindrical shroud extending to the bottom without touching it. Discharge tubes extending to the bottom are connected to the shroud. As the liquid surrounding the heating element is heated,

  6. Folding in and out: passive morphing in flapping wings.

    PubMed

    Stowers, Amanda K; Lentink, David

    2015-04-01

    We present a new mechanism for passive wing morphing of flapping wings inspired by bat and bird wing morphology. The mechanism consists of an unactuated hand wing connected to the arm wing with a wrist joint. Flapping motion generates centrifugal accelerations in the hand wing, forcing it to unfold passively. Using a robotic model in hover, we made kinematic measurements of unfolding kinematics as functions of the non-dimensional wingspan fold ratio (2-2.5) and flapping frequency (5-17 Hz) using stereo high-speed cameras. We find that the wings unfold passively within one to two flaps and remain unfolded with only small amplitude oscillations. To better understand the passive dynamics, we constructed a computer model of the unfolding process based on rigid body dynamics, contact models, and aerodynamic correlations. This model predicts the measured passive unfolding within about one flap and shows that unfolding is driven by centrifugal acceleration induced by flapping. The simulations also predict that relative unfolding time only weakly depends on flapping frequency and can be reduced to less than half a wingbeat by increasing flapping amplitude. Subsequent dimensional analysis shows that the time required to unfold passively is of the same order of magnitude as the flapping period. This suggests that centrifugal acceleration can drive passive unfolding within approximately one wingbeat in small and large wings. Finally, we show experimentally that passive unfolding wings can withstand impact with a branch, by first folding and then unfolding passively. This mechanism enables flapping robots to squeeze through clutter without sophisticated control. Passive unfolding also provides a new avenue in morphing wing design that makes future flapping morphing wings possibly more energy efficient and light-weight. Simultaneously these results point to possible inertia driven, and therefore metabolically efficient, control strategies in bats and birds to morph or recover within a beat. PMID:25807583

  7. Gene-gene and gene-environment interactions in the etiology of type 2 diabetes mellitus in the population of Hyderabad, India.

    PubMed

    Uma Jyothi, Kommoju; Reddy, Battini Mohan

    2015-09-01

    Fifteen SNPs from nine different genes were genotyped on 1379 individuals, 758 T2DM patients and 621 controls, from the city of Hyderabad, India, using Sequenom Massarray platform. These data were analyzed to examine the role of gene-gene and gene-environment interactions in the manifestation of T2DM. The multivariate analysis suggests that TCF7L2, CDKAL1, IGF2BP2, HHEX and PPARG genes are significantly associated with T2DM, albeit only the first two of the above 5 were associated in the univariate analysis. Significant gene-gene and gene-environment interactions were also observed with reference to TCF7L2, CAPN10 and CDKAL1 genes, highlighting their importance in the pathophysiology of T2DM. In the analysis for cumulative effect of risk alleles, SLC30A8 steps in as significant contributor to the disease by its presence in all combinations of risk alleles. A striking difference between risk allele categories, 1-4 and 5-6, was evident in showing protective and susceptible roles, respectively, while the latter was characterized by the presence of TCF7L2 and CDKAL1 variants. Overall, these two genes TCF7L2 and CDKAL1 showed strong association with T2DM, either individually or in interaction with the other genes. However, we need further studies on gene-gene and gene-environment interactions among heterogeneous Indian populations to obtain unequivocal conclusions that are applicable for the Indian population as a whole. PMID:26042206

  8. Gene–gene and gene–environment interactions in the etiology of type 2 diabetes mellitus in the population of Hyderabad, India

    PubMed Central

    Uma Jyothi, Kommoju; Reddy, Battini Mohan

    2015-01-01

    Fifteen SNPs from nine different genes were genotyped on 1379 individuals, 758 T2DM patients and 621 controls, from the city of Hyderabad, India, using Sequenom Massarray platform. These data were analyzed to examine the role of gene–gene and gene–environment interactions in the manifestation of T2DM. The multivariate analysis suggests that TCF7L2, CDKAL1, IGF2BP2, HHEX and PPARG genes are significantly associated with T2DM, albeit only the first two of the above 5 were associated in the univariate analysis. Significant gene–gene and gene–environment interactions were also observed with reference to TCF7L2, CAPN10 and CDKAL1 genes, highlighting their importance in the pathophysiology of T2DM. In the analysis for cumulative effect of risk alleles, SLC30A8 steps in as significant contributor to the disease by its presence in all combinations of risk alleles. A striking difference between risk allele categories, 1–4 and 5–6, was evident in showing protective and susceptible roles, respectively, while the latter was characterized by the presence of TCF7L2 and CDKAL1 variants. Overall, these two genes TCF7L2 and CDKAL1 showed strong association with T2DM, either individually or in interaction with the other genes. However, we need further studies on gene–gene and gene–environment interactions among heterogeneous Indian populations to obtain unequivocal conclusions that are applicable for the Indian population as a whole. PMID:26042206

  9. Multiple Analytical Approaches Reveal Distinct Gene-Environment Interactions in Smokers and Non Smokers in Lung Cancer

    PubMed Central

    Ihsan, Rakhshan; Chauhan, Pradeep Singh; Mishra, Ashwani Kumar; Yadav, Dhirendra Singh; Kaushal, Mishi; Sharma, Jagannath Dev; Zomawia, Eric; Verma, Yogesh; Kapur, Sujala; Saxena, Sunita

    2011-01-01

    Complex disease such as cancer results from interactions of multiple genetic and environmental factors. Studying these factors singularly cannot explain the underlying pathogenetic mechanism of the disease. Multi-analytical approach, including logistic regression (LR), classification and regression tree (CART) and multifactor dimensionality reduction (MDR), was applied in 188 lung cancer cases and 290 controls to explore high order interactions among xenobiotic metabolizing genes and environmental risk factors. Smoking was identified as the predominant risk factor by all three analytical approaches. Individually, CYP1A1*2A polymorphism was significantly associated with increased lung cancer risk (OR?=?1.69;95%CI?=?1.11–2.59,p?=?0.01), whereas EPHX1 Tyr113His and SULT1A1 Arg213His conferred reduced risk (OR?=?0.40;95%CI?=?0.25–0.65,p<0.001 and OR?=?0.51;95%CI?=?0.33–0.78,p?=?0.002 respectively). In smokers, EPHX1 Tyr113His and SULT1A1 Arg213His polymorphisms reduced the risk of lung cancer, whereas CYP1A1*2A, CYP1A1*2C and GSTP1 Ile105Val imparted increased risk in non-smokers only. While exploring non-linear interactions through CART analysis, smokers carrying the combination of EPHX1 113TC (Tyr/His), SULT1A1 213GG (Arg/Arg) or AA (His/His) and GSTM1 null genotypes showed the highest risk for lung cancer (OR?=?3.73;95%CI?=?1.33–10.55,p?=?0.006), whereas combined effect of CYP1A1*2A 6235CC or TC, SULT1A1 213GG (Arg/Arg) and betel quid chewing showed maximum risk in non-smokers (OR?=?2.93;95%CI?=?1.15–7.51,p?=?0.01). MDR analysis identified two distinct predictor models for the risk of lung cancer in smokers (tobacco chewing, EPHX1 Tyr113His, and SULT1A1 Arg213His) and non-smokers (CYP1A1*2A, GSTP1 Ile105Val and SULT1A1 Arg213His) with testing balance accuracy (TBA) of 0.6436 and 0.6677 respectively. Interaction entropy interpretations of MDR results showed non-additive interactions of tobacco chewing with SULT1A1 Arg213His and EPHX1 Tyr113His in smokers and SULT1A1 Arg213His with GSTP1 Ile105Val and CYP1A1*2C in nonsmokers. These results identified distinct gene-gene and gene environment interactions in smokers and non-smokers, which confirms the importance of multifactorial interaction in risk assessment of lung cancer. PMID:22206016

  10. Passivated niobium cavities

    DOEpatents

    Myneni, Ganapati Rao (Yorktown, VA); Hjorvarsson, Bjorgvin (Lagga Arby, SE); Ciovati, Gianluigi (Newport News, VA)

    2006-12-19

    A niobium cavity exhibiting high quality factors at high gradients is provided by treating a niobium cavity through a process comprising: 1) removing surface oxides by plasma etching or a similar process; 2) removing hydrogen or other gases absorbed in the bulk niobium by high temperature treatment of the cavity under ultra high vacuum to achieve hydrogen outgassing; and 3) assuring the long term chemical stability of the niobium cavity by applying a passivating layer of a superconducting material having a superconducting transition temperature higher than niobium thereby reducing losses from electron (cooper pair) scattering in the near surface region of the interior of the niobium cavity. According to a preferred embodiment, the passivating layer comprises niobium nitride (NbN) applied by reactive sputtering.

  11. Passive fetal monitoring sensor

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J. (inventor); Hall, Earl T. (inventor); Baker, Donald A. (inventor); Bryant, Timothy D. (inventor)

    1992-01-01

    An ambulatory, passive sensor for use in a fetal monitoring system is discussed. The invention is comprised of a piezoelectric polymer film, combined with a metallic mounting plate fastened to a belt, and electrically connected to a signal processing unit by means of a shielded cable. The purpose of the sensor is to receive pressure pulses emitted by a fetus inside an expectant mother. Additionally, the monitor will filter out pressure pulses arising from other sources, such as the maternal heart.

  12. Passivation of stainless steel

    Microsoft Academic Search

    R. R Maller

    1998-01-01

    This paper, the 19th in a series of articles on the hygienic design of food processing equipment published in TIFS, introduces the first joint EHEDG\\/3-A Update article in the series, a set of guidelines for the hygienic passivation of stainless steel surfaces intended for food-contact use. These guidelines have been prepared on behalf of the US-based 3-A Steering Committee and

  13. Is the Gene-Environment Interaction Paradigm Relevant to Genome-Wide Studies? The Case of Education and Body Mass Index

    PubMed Central

    Boardman, Jason D.; Domingue, Benjamin W.; Blalock, Casey L.; Haberstick, Brett C.; Harris, Kathleen Mullan; McQueen, Matthew B.

    2014-01-01

    This study uses data from the Framingham Heart Study to examine the relevance of the gene-environment interaction paradigm for genome-wide association studies (GWAS). We use completed college education as our environmental measure and estimate the interactive effect of genotype and education on body mass index (BMI) using 260,402 single-nucleotide polymorphisms (SNPs). Our results highlight the sensitivity of parameter estimates obtained from GWAS models and the difficulty of framing genome-wide results using the existing gene-environment interaction typology. We argue that SNP-environment interactions across the human genome are not likely to provide consistent evidence regarding genetic influences on health that differ by environment. Nevertheless, genome-wide data contain rich information about individual respondents, and we demonstrate the utility of this type of data. We highlight the fact that GWAS is just one use of genome-wide data, and we encourage demographers to develop methods that incorporate this vast amount of information from respondents into their analyses. PMID:24281739

  14. Mind the gap: why many geneticists and psychological scientists have discrepant views about gene-environment interaction (G×E) research.

    PubMed

    Duncan, Laramie E; Pollastri, Alisha R; Smoller, Jordan W

    2014-04-01

    As our field seeks to elucidate the biopsychosocial etiologies of mental health disorders, many traditional psychological and social science researchers have added, or plan to add, genetic components to their programs of research. An understanding of the history, methods, and perspectives of the psychiatric genetics community is useful in this pursuit. In this article we provide a brief overview of psychiatric genetic methods and findings. This overview lays the groundwork for a more thorough review of gene-environment interaction (G×E) research and the candidate gene approach to G×E research that remains popular among many psychologists and social scientists. We describe the differences in perspective between psychiatric geneticists and psychological scientists that have contributed to a growing divide between the research cited and conducted by these two related disciplines. Finally, we outline a strategy for the future of research on gene-environment interactions that capitalizes on the relative strengths of each discipline. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24750075

  15. Discovering pure gene-environment interactions in blood pressure genome-wide association studies data: a two-step approach incorporating new statistics.

    PubMed

    Wang, Maggie Haitian; Huang, Chien-Hsun; Zheng, Tian; Lo, Shaw-Hwa; Hu, Inchi

    2014-01-01

    Environment has long been known to play an important part in disease etiology. However, not many genome-wide association studies take environmental factors into consideration. There is also a need for new methods to identify the gene-environment interactions. In this study, we propose a 2-step approach incorporating an influence measure that capturespure gene-environment effect. We found that pure gene-age interaction has a stronger association than considering the genetic effect alone for systolic blood pressure, measured by counting the number of single-nucleotide polymorphisms (SNPs)reaching a certain significance level. We analyzed the subjects by dividing them into two age groups and found no overlap in the top identified SNPs between them. This suggested that age might have a nonlinear effect on genetic association. Furthermore, the scores of the top SNPs for the two age subgroups were about 3times those obtained when using all subjects for systolic blood pressure. In addition, the scores of the older age subgroup were much higher than those for the younger group. The results suggest that genetic effects are stronger in older age and that genetic association studies should take environmental effects into consideration, especially age. PMID:25519396

  16. Optimizing passive quantum clocks

    NASA Astrophysics Data System (ADS)

    Mullan, Michael; Knill, Emanuel

    2014-10-01

    We describe protocols for passive atomic clocks based on quantum interrogation of the atoms. Unlike previous techniques, our protocols are adaptive and take advantage of prior information about the clock's state. To reduce deviations from an ideal clock, each interrogation is optimized by means of a semidefinite program for atomic state preparation and measurement whose objective function depends on the prior information. Our knowledge of the clock's state is maintained according to a Bayesian model that accounts for noise and measurement results. We implement a full simulation of a running clock with power-law noise models and find significant improvements by applying our techniques.

  17. Passive-solar construction handbook

    SciTech Connect

    Levy, E.; Evans, D.; Gardstein, C.

    1981-02-01

    Many of the basic elements of passive solar design are reviewed. Passive solar construction is covered according to system type, each system type discussion including a general discussion of the important design and construction issues which apply to the particular system and case studies illustrating designed and built examples of the system type. The three basic types of passive solar systems discussed are direct gain, thermal storage wall, and attached sunspace. Thermal performance and construction information is presented for typical materials used in passive solar collector components, storage components, and control components. Appended are an overview of analysis methods and a technique for estimating performance. (LEW)

  18. Passive-solar construction handbook

    NASA Astrophysics Data System (ADS)

    1981-09-01

    An identification and explanation of pertinent considerations in the construction of passively solar heated buildings are presented. Toward that end, the handbook discusses solar design principles, site planning and access, system components, construction details, financial considerations and other items which are essential considerations in passive solar design. The handbook was designed for a multitude of uses: as an instructional tool in workshops and seminars; as a compendium of passive solar design elements; and, as a reference guide to building trade professionals entering passive solar construction.

  19. Passivity Analysis and Passivation of Interconnected Event-Triggered Feedback

    E-print Network

    Antsaklis, Panos

    its power in compositional design of cyber-physical systems. Although passivity theory has been of energy across passive components in the circuit theory field, see e.g. Anderson and Vongpanitlerd [1973 in theory and practice, see e.g. Bao and Lee [2007], Khalil [2002], Ebenbauer et al. [2009]. The significant

  20. Passive scalar intermittency in compressible flow

    E-print Network

    A. Celani; A. Lanotte; A. Mazzino

    1999-06-07

    A compressible generalization of the Kraichnan model (Phys. Rev. Lett. 72, 1016 (1994)) of passive scalar advection is considered. The dynamical role of compressibility on the intermittency of the scalar statistics is investigated for the direct cascade regime. Simple physical arguments suggest that an enhanced intermittency should appear for increasing compressibility, due to the slowing down of Lagrangian trajectory separations. This is confirmed by a numerical study of the dependence of intermittency exponents on the degree of compressibility, by a Lagrangian method for calculating simultaneous N-point tracer correlations.

  1. Fly ash carbon passivation

    DOEpatents

    La Count, Robert B; Baltrus, John P; Kern, Douglas G

    2013-05-14

    A thermal method to passivate the carbon and/or other components in fly ash significantly decreases adsorption. The passivated carbon remains in the fly ash. Heating the fly ash to about 500 and 800 degrees C. under inert gas conditions sharply decreases the amount of surfactant adsorbed by the fly ash recovered after thermal treatment despite the fact that the carbon content remains in the fly ash. Using oxygen and inert gas mixtures, the present invention shows that a thermal treatment to about 500 degrees C. also sharply decreases the surfactant adsorption of the recovered fly ash even though most of the carbon remains intact. Also, thermal treatment to about 800 degrees C. under these same oxidative conditions shows a sharp decrease in surfactant adsorption of the recovered fly ash due to the fact that the carbon has been removed. This experiment simulates the various "carbon burnout" methods and is not a claim in this method. The present invention provides a thermal method of deactivating high carbon fly ash toward adsorption of AEAs while retaining the fly ash carbon. The fly ash can be used, for example, as a partial Portland cement replacement in air-entrained concrete, in conductive and other concretes, and for other applications.

  2. Passive-Solar-Heating Analysis: a new ASHRAE manual

    SciTech Connect

    Balcomb, J.D.

    1983-01-01

    The forthcoming ASHRAE book, Passive Solar Heating Analysis, is described. ASHRAE approval procedures are discussed. An overview of the contents is given. The development of the solar load ratio correlations is described, and the applicability of the analysis method is discussed.

  3. Passive multi-static radiometric detection of moving targets

    Microsoft Academic Search

    Krzysztof S. Kulpa

    2004-01-01

    The paper presents the concept of passive detection of moving targets based on thermal radiation in the microwave region. The fundamental problem istinction between stationary and moving targets is solved by range-Doppler correlation between signals obtained from different localizations in multi-static radiometric antenna constellations. The range equation and other limitations of the presented method are also discussed in the paper.

  4. NEXT-GENERATION ANALYSIS OF CATARACTS: DETERMINING KNOWLEDGE DRIVEN GENE-GENE INTERACTIONS USING BIOFILTER, AND GENE-ENVIRONMENT INTERACTIONS USING THE PHENX TOOLKIT*

    PubMed Central

    Pendergrass, Sarah A.; Verma, Shefali S.; Holzinger, Emily R.; Moore, Carrie B.; Wallace, John; Dudek, Scott M.; Huggins, Wayne; Kitchner, Terrie; Waudby, Carol; Berg, Richard; McCarty, Catherine A.; Ritchie, Marylyn D.

    2013-01-01

    Investigating the association between biobank derived genomic data and the information of linked electronic health records (EHRs) is an emerging area of research for dissecting the architecture of complex human traits, where cases and controls for study are defined through the use of electronic phenotyping algorithms deployed in large EHR systems. For our study, 2580 cataract cases and 1367 controls were identified within the Marshfield Personalized Medicine Research Project (PMRP) Biobank and linked EHR, which is a member of the NHGRI-funded electronic Medical Records and Genomics (eMERGE) Network. Our goal was to explore potential gene-gene and gene-environment interactions within these data for 529,431 single nucleotide polymorphisms (SNPs) with minor allele frequency > 1%, in order to explore higher level associations with cataract risk beyond investigations of single SNP-phenotype associations. To build our SNP-SNP interaction models we utilized a prior-knowledge driven filtering method called Biofilter to minimize the multiple testing burden of exploring the vast array of interaction models possible from our extensive number of SNPs. Using the Biofilter, we developed 57,376 prior-knowledge directed SNP-SNP models to test for association with cataract status. We selected models that required 6 sources of external domain knowledge. We identified 5 statistically significant models with an interaction term with p-value < 0.05, as well as an overall model with p-value < 0.05 associated with cataract status. We also conducted gene-environment interaction analyses for all GWAS SNPs and a set of environmental factors from the PhenX Toolkit: smoking, UV exposure, and alcohol use; these environmental factors have been previously associated with the formation of cataracts. We found a total of 288 models that exhibit an interaction term with a p-value ? 1×10?4 associated with cataract status. Our results show these approaches enable advanced searches for epistasis and gene-environment interactions beyond GWAS, and that the EHR based approach provides an additional source of data for seeking these advanced explanatory models of the etiology of complex disease/outcome such as cataracts. PMID:23424120

  5. Thermal desorption for passive dosimeter 

    E-print Network

    Liu, Wen-Chen

    1981-01-01

    temperature for 21 a passive dosimeter loaded vrith an organic chemical that ould provide the maximum desorption effi- ciency during thermal desorption; 2. To compare desorption efficiencies determined using thermal desorption and solvent desorption... S LIST CF FIGUHES II, THODUCT CI LIT=HATUHE BEVIES . Passive Dosimeter Activated Charcoal Theories of Adsorption Desorption IIethods Solvent Desorption Thermal Desorption Desorption Efficiency Determination Objectives NETHODOLOGY Chemicals...

  6. Passive Greenhouses and Ecological Reconstruction

    Microsoft Academic Search

    V. E. Balas; M. M. Balas; M. V. Putin-Racovita

    2008-01-01

    This paper is discussing the ecological reconstruction opportunity opened by the extended use of the energetic passive greenhouses, independent of any conventional infrastructure (water, gas, electricity). A specific passive greenhouse configuration is considered: the main heating device is a heat pump extracting energy from cold underground water. A dc wind generator is supplying the small amount of energy necessary for

  7. Surface passivation in diamond nucleation

    NASA Astrophysics Data System (ADS)

    Lee, C. H.; Lin, Z. D.; Shang, N. G.; Liao, L. S.; Bello, I.; Wang, N.; Lee, S. T.

    2000-12-01

    Surface passivation is introduced to suppress the deleterious effect of Si surface oxides and thus enhance diamond heteroepitaxial nucleation. Surface composition and diamond nucleation and growth on H-, Br-, and I-passivated Si surfaces were studied. X-ray photoelectron spectroscopy showed that the passivated Si surfaces were free of silicon oxides and carbides. Remarkable enhancement in nucleation was achieved on passivated surfaces and the nucleation density obtained on a Br-passivated Si surface reached 1010 cm-2. Programmable temperature desorption revealed that the adsorbate desorption temperature increased in the order of H, I, and Br passivation. The same order of increase was also observed in the saturation value of electron emission current from the passivated surfaces, which was related to the degree of nucleation. Nucleation enhancement was shown to be greater when the adsorbate desorption temperature is closer to the nucleation temperature, so that more adsorbate- and oxide-free Si surface area would be available for nucleation. The study established that surface passivation is potentially an effective approach for diamond heteroepitaxial nucleation.

  8. Failure Analysis of Passive Devices

    Microsoft Academic Search

    John E. Mann

    1978-01-01

    The failure analysis of passive devices requires all the skills and technology used in the failure analysis of solid state devices. Passive devices use similar manufacturing methods compared to solid state techniques to accomplish the finished device. Thin oxides, used in the manufacturing of tantalum slug capacitors, are subject to current and voltage transients which concern analysts on MOS structures.

  9. Failure analysis of passive devices

    Microsoft Academic Search

    J. E. Mann

    1978-01-01

    The failure analysis of passive devices requires all the skills and technology used in the failure analysis of solid state devices. Passive devices use similar manufacturing methods compared to solid state techniques to accomplish the finished device. Thin oxides, used in the manufacturing of tantalum slug capacitors, are subject to current and voltage transients which concern analysts on MOS structures.

  10. Empirical Hierarchical Bayes Approach to Gene-Environment Interactions: Development and Application to Genome-Wide Association Studies of Lung Cancer in TRICL

    PubMed Central

    Amos, Christopher I.; Brennan, Paul; Fehringer, Gord; Gaborieau, Valerie; Han, Younghun; Heinrich, Joachim; Chang-Claude, Jenny; Hung, Rayjean J.; Müller-Nurasyid, Martina; Risch, Angela; Thomas, Duncan; Bickeböller, Heike

    2014-01-01

    The analysis of gene-environment (GxE) interactions remains one of the greatest challenges in the post-genome-wide-association-studies (GWAS) era. Recent methods constitute a compromise between the robust but underpowered case-control and powerful case-only methods. Inferences of the latter are biased when the assumption of gene-environment (G-E) independence fails. We propose a novel empirical hierarchical Bayes approach to GxE interaction (EHB-GE), which benefits from greater power while accounting for population-based G-E dependence. Building on Lewinger et al.'s ([2007] Genet Epidemiol 31:871-882) hierarchical Bayes prioritization approach, the method utilizes posterior G-E association estimates in controls based on G-E information across the genome to adjust for it in resulting test statistics. These posteriori estimates are subtracted from the corresponding G-E association coefficients within cases. We compared EHB-GE with rival methods using simulation. EHB-GE has similar or greater rank power to detect GxE interactions in the presence of large numbers of G-E associations with weak to strong effects or only a low number of such associations with large effect. When there are no or only a few weak G-E associations, Murcray et al.'s method ([2009] Am J Epidemiol 169:219-226) identifies markers with low GxE interaction effects better. We applied EHB-GE and competing methods to four lung cancer case-control GWAS from the TRICL/ILCCO consortium with smoking as environmental factor. Genes identified by the EHB-GE approach are reasonable candidates, suggesting usefulness of the method. PMID:23893921

  11. Gene-environment interactions and obesity traits among postmenopausal African-American and Hispanic women in the Women's Health Initiative SHARe Study.

    PubMed

    Velez Edwards, Digna R; Naj, Adam C; Monda, Keri; North, Kari E; Neuhouser, Marian; Magvanjav, Oyunbileg; Kusimo, Ibukun; Vitolins, Mara Z; Manson, Joann E; O'Sullivan, Mary Jo; Rampersaud, Evadnie; Edwards, Todd L

    2013-03-01

    Genome-wide association studies (GWAS) of obesity measures have identified associations with single nucleotide polymorphisms (SNPs). However, no large-scale evaluation of gene-environment interactions has been performed. We conducted a search of gene-environment (G × E) interactions in post-menopausal African-American and Hispanic women from the Women's Health Initiative SNP Health Association Resource GWAS study. Single SNP linear regression on body mass index (BMI) and waist-to-hip circumference ratio (WHR) adjusted for multidimensional-scaling-derived axes of ancestry and age was run in race-stratified data with 871,512 SNPs available from African-Americans (N = 8,203) and 786,776 SNPs from Hispanics (N = 3,484). Tests of G × E interaction at all SNPs for recreational physical activity (m h/week), dietary energy intake (kcal/day), alcohol intake (categorical), cigarette smoking years, and cigarette smoking (ever vs. never) were run in African-Americans and Hispanics adjusted for ancestry and age at interview, followed by meta-analysis of G × E interaction terms. The strongest evidence for concordant G × E interactions in African-Americans and Hispanics was for smoking and marker rs10133840 (Q statistic P = 0.70, beta = -0.01, P = 3.81 × 10(-7)) with BMI as the outcome. The strongest evidence for G × E interaction within a cohort was in African-Americans with WHR as outcome for dietary energy intake and rs9557704 (SNP × kcal = -0.04, P = 2.17 × 10(-7)). No results exceeded the Bonferroni-corrected statistical significance threshold. PMID:23192594

  12. Passive containment cooling system

    DOEpatents

    Billig, P.F.; Cooke, F.E.; Fitch, J.R.

    1994-01-25

    A passive containment cooling system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel and is vented to the drywell. An isolation pool is disposed above the GDCS pool and includes an isolation condenser therein. The condenser has an inlet line disposed in flow communication with the drywell for receiving the non-condensable gas along with any steam released therein following a loss-of-coolant accident (LOCA). The condenser also has an outlet line disposed in flow communication with the drywell for returning to the drywell both liquid condensate produced upon cooling of the steam and the non-condensable gas for reducing pressure within the containment vessel following the LOCA. 1 figure.

  13. Passive fathometer processing.

    PubMed

    Gerstoft, Peter; Hodgkiss, William S; Siderius, Martin; Huang, Chen-Fen; Harrison, Chris H

    2008-03-01

    Ocean acoustic noise can be processed efficiently to extract Green's function information between two receivers. By using noise array-processing techniques, it has been demonstrated that a passive array can be used as a fathometer [Siderius, et al., J. Acoust. Soc. Am. 120, 1315-1323 (2006)]. Here, this approach is derived in both frequency and time domains and the output corresponds to the reflection sequence. From this reflection sequence, it is possible to extract seabed layering. In the ocean waveguide, most of the energy is horizontally propagating, whereas the bottom information is contained in the vertically propagating noise. Extracting the seabed information requires a dense array, since the resolution of the bottom layer is about half the array spacing. If velocity sensors are used instead of pressure sensors, the array spacing requirement can be relaxed and simulations show that just one vertical velocity sensor is sufficient. PMID:18345818

  14. Passive containment cooling system

    DOEpatents

    Billig, Paul F. (San Jose, CA); Cooke, Franklin E. (San Jose, CA); Fitch, James R. (San Jose, CA)

    1994-01-01

    A passive containment cooling system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel and is vented to the drywell. An isolation pool is disposed above the GDCS pool and includes an isolation condenser therein. The condenser has an inlet line disposed in flow communication with the drywell for receiving the non-condensable gas along with any steam released therein following a loss-of-coolant accident (LOCA). The condenser also has an outlet line disposed in flow communication with the drywell for returning to the drywell both liquid condensate produced upon cooling of the steam and the non-condensable gas for reducing pressure within the containment vessel following the LOCA.

  15. A short note on passivity, complete passivity and virtual temperatures

    E-print Network

    Paul Skrzypczyk; Ralph Silva; Nicolas Brunner

    2014-12-17

    We give a simple and intuitive proof that the only states which are completely passive, i.e. those states from which work cannot be extracted even with infinitely many copies, are Gibbs states at positive temperatures. The proof makes use of the idea of virtual temperatures, i.e. the association of temperatures to transitions. We show that (i) passive states are those where every transition is at a positive temperature, and (ii) completely passive states are those where every transition is at the same positive temperature.

  16. Expansion-based passive ranging

    NASA Technical Reports Server (NTRS)

    Barniv, Yair

    1993-01-01

    A new technique of passive ranging which is based on utilizing the image-plane expansion experienced by every object as its distance from the sensor decreases is described. This technique belongs in the feature/object-based family. The motion and shape of a small window, assumed to be fully contained inside the boundaries of some object, is approximated by an affine transformation. The parameters of the transformation matrix are derived by initially comparing successive images, and progressively increasing the image time separation so as to achieve much larger triangulation baseline than currently possible. Depth is directly derived from the expansion part of the transformation. To a first approximation, image-plane expansion is independent of image-plane location with respect to the focus of expansion (FOE) and of platform maneuvers. Thus, an expansion-based method has the potential of providing a reliable range in the difficult image area around the FOE. In areas far from the FOE the shift parameters of the affine transformation can provide more accurate depth information than the expansion alone, and can thus be used similarly to the way they were used in conjunction with the Inertial Navigation Unit (INU) and Kalman filtering. However, the performance of a shift-based algorithm, when the shifts are derived from the affine transformation, would be much improved compared to current algorithms because the shifts - as well as the other parameters - can be obtained between widely separated images. Thus, the main advantage of this new approach is that, allowing the tracked window to expand and rotate, in addition to moving laterally, enables one to correlate images over a very long time span which, in turn, translates into a large spatial baseline - resulting in a proportionately higher depth accuracy.

  17. Expansion-based passive ranging

    NASA Technical Reports Server (NTRS)

    Barniv, Yair

    1993-01-01

    This paper describes a new technique of passive ranging which is based on utilizing the image-plane expansion experienced by every object as its distance from the sensor decreases. This technique belongs in the feature/object-based family. The motion and shape of a small window, assumed to be fully contained inside the boundaries of some object, is approximated by an affine transformation. The parameters of the transformation matrix are derived by initially comparing successive images, and progressively increasing the image time separation so as to achieve much larger triangulation baseline than currently possible. Depth is directly derived from the expansion part of the transformation. To a first approximation, image-plane expansion is independent of image-plane location with respect to the focus of expansion (FOE) and of platform maneuvers. Thus, an expansion-based method has the potential of providing a reliable range in the difficult image area around the FOE. In areas far from the FOE the shift parameters of the affine transformation can provide more accurate depth information than the expansion alone, and can thus be used similarly to the way they have been used in conjunction with the Inertial Navigation Unit (INU) and Kalman filtering. However, the performance of a shift-based algorithm, when the shifts are derived from the affine transformation, would be much improved compared to current algorithms because the shifts--as well as the other parameters--can be obtained between widely separated images. Thus, the main advantage of this new approach is that, allowing the tracked window to expand and rotate, in addition to moving laterally, enables one to correlate images over a very long time span which, in turn, translates into a large spatial baseline resulting in a proportionately higher depth accuracy.

  18. Passive Vaporizing Heat Sink

    NASA Technical Reports Server (NTRS)

    Knowles, TImothy R.; Ashford, Victor A.; Carpenter, Michael G.; Bier, Thomas M.

    2011-01-01

    A passive vaporizing heat sink has been developed as a relatively lightweight, compact alternative to related prior heat sinks based, variously, on evaporation of sprayed liquids or on sublimation of solids. This heat sink is designed for short-term dissipation of a large amount of heat and was originally intended for use in regulating the temperature of spacecraft equipment during launch or re-entry. It could also be useful in a terrestrial setting in which there is a requirement for a lightweight, compact means of short-term cooling. This heat sink includes a hermetic package closed with a pressure-relief valve and containing an expendable and rechargeable coolant liquid (e.g., water) and a conductive carbon-fiber wick. The vapor of the liquid escapes when the temperature exceeds the boiling point corresponding to the vapor pressure determined by the setting of the pressure-relief valve. The great advantage of this heat sink over a melting-paraffin or similar phase-change heat sink of equal capacity is that by virtue of the =10x greater latent heat of vaporization, a coolant-liquid volume equal to =1/10 of the paraffin volume can suffice.

  19. [Passive smoking. Effects on health].

    PubMed

    Trédaniel, J; Zalcman, G; Boffetta, P; Hirsch, A

    1993-05-15

    Passive smoking--also called involuntary or environmental smoking--is the exposure of non-smokers to the tobacco smoke released by smokers. The physico-chemical composition of tobacco smoke, and notably its contents in toxic and carcinogenic substances, is the same in the secondary stream between puffs as in the primary stream released by the smoker. The pathogenic effects of passive smoking are increasingly well known and accepted. A high incidence of respiratory tract infections and of chronic respiratory and asthmatic symptoms is observed in children. In adults, passive smoking seems to be one of the main risk factors for cardiovascular diseases. Its repercussions on the respiratory tracts is difficult to evaluate, but there are marked by an increase of respiratory symptoms and perhaps of chronic obstructive lung diseases. Finally, it is now recognized that passive smoking is a major risk factor for primary lung cancer in non-smokers exposed to tobacco smoke. PMID:8235360

  20. Orion Passive Thermal: Control Overview

    NASA Technical Reports Server (NTRS)

    Alvarez-Hermandez, Angel; Miller, Stephen W.

    2009-01-01

    A general overview of the NASA Orion Passive Thermal Control System (PTCS) is presented. The topics include: 1) Orion in CxP Hierarchy; 2) General Orion Description/Orientation; and 3) Orion PTCS Overview.

  1. Parallel Genetic Changes and Nonparallel Gene–Environment Interactions Characterize the Evolution of Drug Resistance in Yeast

    PubMed Central

    Gerstein, Aleeza C.; Lo, Dara S.; Otto, Sarah P.

    2012-01-01

    Beneficial mutations are required for adaptation to novel environments, yet the range of mutational pathways that are available to a population has been poorly characterized, particularly in eukaryotes. We assessed the genetic changes of the first mutations acquired during adaptation to a novel environment (exposure to the fungicide, nystatin) in 35 haploid lines of Saccharomyces cerevisiae. Through whole-genome resequencing we found that the genomic scope for adaptation was narrow; all adapted lines acquired a mutation in one of four late-acting genes in the ergosterol biosynthesis pathway, with very few other mutations found. Lines that acquired different ergosterol mutations in the same gene exhibited very similar tolerance to nystatin. All lines were found to have a cost relative to wild type in an unstressful environment; the level of this cost was also strongly correlated with the ergosterol gene bearing the mutation. Interestingly, we uncovered both positive and negative effects on tolerance to other harsh environments for mutations in the different ergosterol genes, indicating that these beneficial mutations have effects that differ in sign among environmental challenges. These results demonstrate that although the genomic target was narrow, different adaptive mutations can lead populations down different evolutionary pathways, with respect to their ability to tolerate (or succumb to) other environmental challenges. PMID:22714405

  2. Passive-blind Image Forensics

    Microsoft Academic Search

    Tian-Tsong Ng; Shih-Fu Chang; Ching-Yung Lin; Qibin Sun

    2006-01-01

    In this chapter, we will review the research area of passive-blind image forensics, i.e., an form of image analysis for flnding out the condition of an image without relying on pre-registration or pre-embedded information. We consider the two main functions of passive-blind image forensics as be- ing image forgery detection and image source identiflcation. In this vein, we provide a

  3. Passive Scanning in Modbus Networks

    Microsoft Academic Search

    Jesús González; Mauricio Papa

    2007-01-01

    This paper describes the design and implementation of a passive scanner for Modbus networks. The tool integrates packet parsing\\u000a and passive scanning functionality to interpret Modbus transactions and provide accurate network representations. In particular,\\u000a the scanner monitors Modbus messages to maintain and update state table entries associated with field devices. Entries in\\u000a the state tables record important information including function

  4. Passive vapor extraction feasibility study

    SciTech Connect

    Rohay, V.J.

    1994-06-30

    Demonstration of a passive vapor extraction remediation system is planned for sites in the 200 West Area used in the past for the disposal of waste liquids containing carbon tetrachloride. The passive vapor extraction units will consist of a 4-in.-diameter pipe, a check valve, a canister filled with granular activated carbon, and a wind turbine. The check valve will prevent inflow of air that otherwise would dilute the soil gas and make its subsequent extraction less efficient. The granular activated carbon is used to adsorb the carbon tetrachloride from the air. The wind turbine enhances extraction rates on windy days. Passive vapor extraction units will be designed and operated to meet all applicable or relevant and appropriate requirements. Based on a cost analysis, passive vapor extraction was found to be a cost-effective method for remediation of soils containing lower concentrations of volatile contaminants. Passive vapor extraction used on wells that average 10-stdft{sup 3}/min air flow rates was found to be more cost effective than active vapor extraction for concentrations below 500 parts per million by volume (ppm) of carbon tetrachloride. For wells that average 5-stdft{sup 3}/min air flow rates, passive vapor extraction is more cost effective below 100 ppm.

  5. Associations of PI3KR1 and mTOR polymorphisms with esophageal squamous cell carcinoma risk and gene-environment interactions in Eastern Chinese populations.

    PubMed

    Zhu, Jinhong; Wang, Mengyun; Zhu, Meiling; He, Jin; Wang, Jiu-Cun; Jin, Li; Wang, Xiao-Feng; Xiang, Jia-Qing; Wei, Qingyi

    2015-01-01

    Single nucleotide polymorphisms (SNPs) in the PI3K/PTEN/AKT/mTOR signaling pathway may contribute to carcinogenesis. We genotyped five potentially functional PIK3R1 and mTOR SNPs in 1116 esophageal squamous cell cancer (ESCC) patients and 1117 cancer-free controls to assess their associations with ESCC risk. We observed no association with ESCC risk for any of the selected SNPs. However, the combined analysis of these SNPs revealed that subjects with one-to-three risk genotypes had an increased ESCC risk. Stratified analysis by body mass index (BMI) found that ESCC risk was significantly associated with each of three mTOR SNPs among subjects with BMI < 25.0. Specifically, we found that subjects carrying ? 1 risk genotypes had significantly increased ESCC risk, particularly for males, ever-smokers, ever-drinkers, and those with age > 60, or BMI < 25.0. Moreover, three mTOR haplotypes were associated with an increase in ESCC risk. Our meta-analysis of mTOR rs2295080 and cancer risk provided further evidence that mTOR SNPs might modulate cancer susceptibility. In this population, such risk effects might be modified by other risk factors, highlighting the importance of gene-environment interaction in esophageal carcinogenesis. Additional, larger studies are warranted to validate our findings. PMID:25654238

  6. Nevoid basal cell carcinoma syndrome with medulloblastoma in an African-American boy: A rare case illustrating gene-environment interaction

    SciTech Connect

    Korczak, J.F.; Goldstein, A.M. [National Institutes of Health, Bethesda, MD (United States)] [National Institutes of Health, Bethesda, MD (United States); Kase, R.G. [Westat Inc., Rockville, MD (United States)] [and others] [Westat Inc., Rockville, MD (United States); and others

    1997-03-31

    We present an 8-year-old African-American boy with medulloblastoma and nevoid basal cell carcinoma syndrome (NBCCS) who exhibited the radiosensitive response of basal cell carcinoma (BCC) formation in the area irradiated for medulloblastoma. Such a response is well-documented in Caucasian NBCCS patients with medulloblastoma. The propositus was diagnosed with medulloblastoma at the age of 2 years and underwent surgery, chemotherapy, and craniospinal irradiation. At the age of 6 years, he was diagnosed with NBCCS following his presentation with a large odontogenic keratocyst of the mandible, pits of the palms and soles and numerous BCCs in the area of the back and neck that had been irradiated previously for medulloblastoma. Examination of other relatives showed that the propositus mother also had NBCCS but was more mildly affected; in particular, she had no BCCs. This case illustrates complex gene-environment interaction, in that increased skin pigmentation in African-Americans is presumably protective against ultraviolet, but not ionizing, radiation. This case and other similar cases in the literature show the importance of considering NBCCS in the differential diagnosis of any patient who presents with a medulloblastoma, especially before the age of 5 years, and of examining other close relatives for signs of NBCCS to determine the patient`s at-risk status. Finally, for individuals who are radiosensitive, protocols that utilize chemotherapy in lieu of radiotherapy should be considered. 27 refs., 4 figs.

  7. Testing for measured gene-environment interaction: problems with the use of cross-product terms and a regression model reparameterization solution.

    PubMed

    Aliev, Fazil; Latendresse, Shawn J; Bacanu, Silviu-Alin; Neale, Michael C; Dick, Danielle M

    2014-03-01

    The study of gene-environment interaction (G × E) has garnered widespread attention. The most common way to assess interaction effects is in a regression model with a G × E interaction term that is a product of the values specified for the genotypic (G) and environmental (E) variables. In this paper we discuss the circumstances under which interaction can be modeled as a product term and cases in which use of a product term is inappropriate and may lead to erroneous conclusions about the presence and nature of interaction effects. In the case of a binary coded genetic variant (as used in dominant and recessive models, or where the minor allele occurs so infrequently that it is not observed in the homozygous state), the regression coefficient corresponding to a significant interaction term reflects a slope difference between the two genotype categories and appropriately characterizes the statistical interaction between the genetic and environmental variables. However, when using a three-category polymorphic genotype, as is commonly done when modeling an additive effect, both false positive and false negative results can occur, and the nature of the interaction can be misrepresented. We present a reparameterized regression equation that accurately captures interaction effects without the constraints imposed by modeling interactions using a single cross-product term. In addition, we provide a series of recommendations for making conclusions about the presence of meaningful G × E interactions, which take into account the nature of the observed interactions and whether they map onto sensible genotypic models. PMID:24531874

  8. Effects of divorce on Dutch boys' and girls' externalizing behavior in Gene × Environment perspective: diathesis stress or differential susceptibility in the Dutch Tracking Adolescents' Individual Lives Survey study?

    PubMed

    Nederhof, Esther; Belsky, Jay; Ormel, Johan; Oldehinkel, Albertine J

    2012-08-01

    The effects of divorce on children's behavioral development have proven to be quite varied across studies, and most developmental and family scholars today appreciate the great heterogeneity in divorce effects. Thus, this inquiry sought to determine whether select dopaminergic genes previously associated with externalizing behavior and/or found to moderate diverse environmental effects (dopamine receptors D2 and D4, catechol-O-methyltransferase) might moderate divorce effects on adolescent self-reported externalizing problems; and, if so, whether evidence of gene-environment (G × E) interaction would prove consistent with diathesis-stress or differential-susceptibility models of environmental action. Data from the first and third wave of the Dutch Tracking Adolescents' Individual Lives Survey (n = 1,134) revealed some evidence of G × E interaction reflecting diathesis-stress but not differential susceptibility. It is intriguing that some evidence pointed to "vantage sensitivity," which are benefits accruing to those with a specific genotype when their parents remained together, the exact opposite of diathesis-stress. The limits of this work are considered, especially with regard to the conditions for testing differential susceptibility, and future directions are outlined. PMID:22781863

  9. Passive solar design: final evaluation, the Passive Studio

    SciTech Connect

    Bremer, Duncan S.; Rose, Stuart

    1980-08-01

    The further evaluation of the workshops in passive design for practicing architects and engineers through delayed interviews with a sample of the participants is reported with particular emphasis on the extent to which the participants have practiced passive design in the three-four months since attending. Also discussed is an unsuccessful attempt to conduct a lower-cost version of the program outside of normal office hours. Finally, the follow-on programs and improvements that the interviews indicated are needed are identified. (MHR)

  10. Synthetic passive margin stratigraphy

    SciTech Connect

    Turcotte, D.L.; Kenyon, P.M.

    1984-06-01

    Synthetic stratigraphic cross sections are derived mathematically for a variety of simple conditions. The variables considered in the mathematical model include variations in sea level, rate of tectonic subsidence, rate of sedimentation, and rate of erosion. Derived stratigraphic relationships include unconformities, correlative conformities and disconformities, coastal onlap, coastal toplap, erosional truncation, pinch-out, and sigmoidal progradational clinoforms. An important conclusion is that the rate of erosion is a dominant variable in determining the type of stratigraphic section observed. The proposed approach may provide the basis for either a forward or inverse modeling of seismic stratigraphic sections.

  11. Autism risk factors: genes, environment, and gene-environment interactions

    PubMed Central

    Chaste, Pauline; Leboyer, Marion

    2012-01-01

    The aim of this review is to summarize the key findings from genetic and epidemiological research, which show that autism is a complex disorder resulting from the combination of genetic and environmental factors. Remarkable advances in the knowledge of genetic causes of autism have resulted from the great efforts made in the field of genetics. The identification of specific alleles contributing to the autism spectrum has supplied important pieces for the autism puzzle. However, many questions remain unanswered, and new questions are raised by recent results. Moreover, given the amount of evidence supporting a significant contribution of environmental factors to autism risk, it is now clear that the search for environmental factors should be reinforced. One aspect of this search that has been neglected so far is the study of interactions between genes and environmental factors. PMID:23226953

  12. All-Passive Nonreciprocal Metasurface

    E-print Network

    Mahmoud, Ahmed M; Engheta, Nader

    2014-01-01

    We introduce a systematic approach to design all-passive subwavelength high performance metasurfaces that exhibit nonreciprocal properties and achieve wave-flow isolation. Moreover we build upon those findings and propose a new paradigm for a quasi-2D metasurface that mimic the nonreciprocal property of Faraday rotation without using any magnetic or electric biasing. We envision that the proposed approaches may serve as a building block for all-passive time-reversal symmetry breaking with potential applications for future nonreciprocal systems and devices.

  13. Photonitride passivating coating for IC's

    NASA Technical Reports Server (NTRS)

    Hall, T. C.; Peters, J. W.

    1980-01-01

    Increased reliability and simplified fabrication result from postassembly preencapsulation passivation process. Photonitride reaction chamber receives silane, ammonia, and mercury from mixing manifold to form passivating coating on IC's. Photonitride layer is barrier to moisture and penetration by mobile ions, and helps to protect IC devices subjected to severe mechanical handling or circuit repair procedures. Process is compatible with variety of wire-bonded lead frame assemblies. Advantages over plasma and sputtering deposition processes are low deposition temperature and zero stray radiation and ion levels.

  14. Passivation of high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Vasquez, Richard P. (inventor)

    1991-01-01

    The surface of high temperature superconductors such as YBa2Cu3O(7-x) are passivated by reacting the native Y, Ba and Cu metal ions with an anion such as sulfate or oxalate to form a surface film that is impervious to water and has a solubility in water of no more than 10(exp -3) M. The passivating treatment is preferably conducted by immersing the surface in dilute aqueous acid solution since more soluble species dissolve into the solution. The treatment does not degrade the superconducting properties of the bulk material.

  15. Active and realistic passive marijuana exposure tested by three immunoassays and GC/MS in urine

    SciTech Connect

    Mule, S.J.; Lomax, P.; Gross, S.J.

    1988-05-01

    Human urine samples obtained before and after active and passive exposure to marijuana were analyzed by immune kits (Roche, Amersham, and Syva) and gas chromatography/mass spectrometry (GC/MS). Seven of eight subjects were positive for the entire five-day test period with one immune kit. The latter correlated with GC/MS in 98% of the samples. Passive inhalation experiments under conditions likely to reflect realistic exposure resulted consistently in less than 10 ng/mL of cannabinoids. The 10-100-ng/mL cannabinoid concentration range essential for detection of occasional and moderate marijuana users is thus unaffected by realistic passive inhalation.

  16. HCI gesture tracking using wearable passive tags

    E-print Network

    Bainbridge, Rachel M

    2010-01-01

    In this thesis. a wearable system is developed to track hand gestures with passive RFID sensor tags. This system was composed of an ultra-high frequency reader and small, passive, finger-worn tags powered by scavenged RFID ...

  17. A partial least-square approach for modeling gene-gene and gene-environment interactions when multiple markers are genotyped.

    PubMed

    Wang, Tao; Ho, Gloria; Ye, Kenny; Strickler, Howard; Elston, Robert C

    2009-01-01

    Genetic association studies achieve an unprecedented level of resolution in mapping disease genes by genotyping dense single nucleotype polymorphisms (SNPs) in a gene region. Meanwhile, these studies require new powerful statistical tools that can optimally handle a large amount of information provided by genotype data. A question that arises is how to model interactions between two genes. Simply modeling all possible interactions between the SNPs in two gene regions is not desirable because a greatly increased number of degrees of freedom can be involved in the test statistic. We introduce an approach to reduce the genotype dimension in modeling interactions. The genotype compression of this approach is built upon the information on both the trait and the cross-locus gametic disequilibrium between SNPs in two interacting genes, in such a way as to parsimoniously model the interactions without loss of useful information in the process of dimension reduction. As a result, it improves power to detect association in the presence of gene-gene interactions. This approach can be similarly applied for modeling gene-environment interactions. We compare this method with other approaches, the corresponding test without modeling any interaction, that based on a saturated interaction model, that based on principal component analysis, and that based on Tukey's one-degree-of-freedom model. Our simulations suggest that this new approach has superior power to that of the other methods. In an application to endometrial cancer case-control data from the Women's Health Initiative, this approach detected AKT1 and AKT2 as being significantly associated with endometrial cancer susceptibility by taking into account their interactions with body mass index. PMID:18615621

  18. The Effect of UGT1A and UGT2B Polymorphisms on Colorectal Cancer Risk: Haplotype Associations and Gene-Environment Interactions

    PubMed Central

    Angstadt, Andrea Y.; Hartman, Terryl J.; Lesko, Samuel M.; Muscat, Joshua E.; Zhu, Junjia; Gallagher, Carla J.; Lazarus, Philip

    2014-01-01

    UDP-glucuronosyltransferases (UGTs) play an important role in the phase II metabolism of exogenous and endogenous compounds. As colorectal cancer (CRC) etiology is thought to involve the biotransformation of dietary factors, UGT polymorphisms may affect CRC risk by altering levels of exposure. Genotyping of over 1800 Caucasian subjects was completed to identify the role of genetic variation in nine UGT1A and five UGT2B genes on CRC risk. Unconditional logistic regression and haplotype analyses were conducted to identify associations with CRC risk and potential gene-environment interactions. UGT1A haplotype analysis found that the T-G haplotype in UGT1A10 exon 1 (block 2: rs17864678, rs10929251) decreased colon cancer risk [proximal (OR = 0.28, 95% CI=0.11–0.69), distal (OR = 0.32, 95% CI=0.12–0.91)] and that the C-T-G haplotype in the 3? region flanking the UGT1A shared exons (block 11: rs7578153, rs10203853, rs6728940) increased CRC risk in males (OR = 2.56, 95% CI=1.10–5.95). A haplotype in UGT2B15 containing a functional variant (rs4148269, K523T) and an intronic SNP (rs6837575) was found to affect rectal cancer risk overall (OR = 2.57, 95% CI=1.21–5.04) and in females (OR = 3.08, 95% CI=1.08–8.74). An interaction was found between high NSAID use and the A-G-T haplotype (block 10: rs6717546, rs1500482, rs7586006) in the UGT1A shared exons that decreased CRC risk. This suggests that UGT genetic variation alters CRC risk differently by anatomical sub-site and gender and that polymorphisms in the UGT1A shared exons may have a regulatory effect on gene expression that allows for the protective effect of NSAIDs on CRC risk. PMID:24822274

  19. Serum Carboxymethyl-lysine, an Advanced Glycation End Product, and Age-Related Macular Degeneration: the Age Gene/Environment Susceptibility-Reykjavik Study

    PubMed Central

    Semba, Richard D.; Cotch, Mary Frances; Gudnason, Vilmundur; Eiríksdottir, Gudny; Harris, Tamara B.; Sun, Kai; Klein, Ronald; Jonasson, Fridbert; Ferrucci, Luigi; Schaumberg, Debra A.

    2014-01-01

    Importance Advanced glycation end products have been implicated in the pathogenesis of age-related macular degeneration (AMD). Objective To investigate the relationship between serum carboxymethyl-lysine (CML), a major circulating advanced glycation end product, and AMD in older adults. Design Cross-sectional study. Setting Population-based sample of older adults in the Age Gene/Environment Susceptibility-Reykjavik Study. Participants 4907 adults, aged ?66 years Exposure Serum CML and risk factors for AMD. Main Outcome Measures Early or late AMD, assessed through fundus images taken through dilated pupils using a 45-degree digital camera and grading for drusen size, type, area, increased retinal pigment, retinal pigment epithelial depigmentation, neovascular lesions, and geographic atrophy using the modified Wisconsin Age-Related Maculopathy Grading System. Results Of the 4907 participants, 1025 (20.9%) had early AMD and 276 (5.6%) had late AMD. Mean (standard deviation [SD]) serum CML concentrations among adults with no AMD, early AMD, and late AMD (exudative AMD and pure geographic atrophy) were 3.0 (0.9), 3.1 (1.0), and 3.1 (0.9) ?mol/L, respectively (P = 0.07). Log serum CML (per 1 log SD) was not associated with any AMD (early and late AMD) (Odds Ratio [O.R.] 0.97, 95% Confidence Interval [C.I.] 0.90, 1.04, P = 0.44) or with late AMD (O.R. = 0.94, 95% C.I. 0.82, 1.08, P = 0.36) in respective multivariable logistic regression models adjusting for age, sex, body mass index, smoking, and renal function. Conclusion Higher serum CML had no significant cross-sectional association with prevalent AMD in this large population-based cohort of older adults in Iceland. PMID:24481410

  20. Evidence of Gene?Environment Interaction for Two Genes on Chromosome 4 and Environmental Tobacco Smoke in Controlling the Risk of Nonsyndromic Cleft Palate

    PubMed Central

    Wu, Tao; Schwender, Holger; Ruczinski, Ingo; Murray, Jeffrey C.; Marazita, Mary L.; Munger, Ronald G.; Hetmanski, Jacqueline B.; Parker, Margaret M.; Wang, Ping; Murray, Tanda; Taub, Margaret; Li, Shuai; Redett, Richard J.; Fallin, M. Daniele; Liang, Kung Yee; Wu-Chou, Yah Huei; Chong, Samuel S.; Yeow, Vincent; Ye, Xiaoqian; Wang, Hong; Huang, Shangzhi; Jabs, Ethylin W.; Shi, Bing; Wilcox, Allen J.; Jee, Sun Ha; Scott, Alan F.; Beaty, Terri H.

    2014-01-01

    Nonsyndromic cleft palate (CP) is one of the most common human birth defects and both genetic and environmental risk factors contribute to its etiology. We conducted a genome-wide association study (GWAS) using 550 CP case-parent trios ascertained in an international consortium. Stratified analysis among trios with different ancestries was performed to test for GxE interactions with common maternal exposures using conditional logistic regression models. While no single nucleotide polymorphism (SNP) achieved genome-wide significance when considered alone, markers in SLC2A9 and the neighboring WDR1 on chromosome 4p16.1 gave suggestive evidence of gene-environment interaction with environmental tobacco smoke (ETS) among 259 Asian trios when the models included a term for GxE interaction. Multiple SNPs in these two genes were associated with increased risk of nonsyndromic CP if the mother was exposed to ETS during the peri-conceptual period (3 months prior to conception through the first trimester). When maternal ETS was considered, fifteen of 135 SNPs mapping to SLC2A9 and 9 of 59 SNPs in WDR1 gave P values approaching genome-wide significance (10?6

  1. Comparison of Different Haplotype-Based Haplotype-Based Association Methods for Gene-Environment (G×E) Interactions in Case-Control Studies when Haplotype-Phase Is Ambiguous

    Microsoft Academic Search

    Rebecca Hein; Lars Beckmann; Jenny Chang-Claude

    2009-01-01

    Objective: We compared four haplotype-based approaches for the analysis of gene-environment interactions when haplotype-phase is ambiguous. The methods employ different versions of the expectation maximization algorithm and differ in the choice of the reference group and in the way the risk of disease is modeled (retrospective versus prospective). Furthermore, the methods are based on distinct assumptions (such as Hardy Weinberg

  2. Passive solar roof ice melter

    Microsoft Academic Search

    Deutz

    1981-01-01

    An elongated passive solar roof ice melter is placed on top of accumulated ice and snow including an ice dam along the lower edge of a roof of a heated building and is held against longitudinal movement with respect to itself. The melter includes a bottom wall having an upper surface highly absorbent to radiant solar energy; a first window

  3. Passive Tuneable Fibers and Matrices

    Microsoft Academic Search

    Carolyn Dry

    1992-01-01

    Active smart electrorheological fluids in building materials are expensive, need to be widely dispersed, and require large amounts of electricity. These practical considerations led to the consideration of ways of having similar effects in a matrix but using different materials. Tuneable fibers is an inexpensive dispersed passive system, requiring no electricity. The modulus of elasticity of a solid-filled fiber is

  4. Monitored passive-solar buildings

    NASA Astrophysics Data System (ADS)

    Jones, R. W.

    1982-06-01

    Selected performance results from six monitored passive and hybrid solar heated buildings are presented. These employ: a two story trombe wall; a thermosyphoning solar air heater with rock bin storage; a greenhouse; a composite concrete and water trombe wall; two story sunspace; and, for a mobile/modular home, direct gain and roof pond.

  5. Security of passive access vehicle

    Microsoft Academic Search

    Ansaf Ibrahem Alrabady

    2002-01-01

    A passive vehicle system for automotive applications is an evolution of the popular remote keyless entry systems. It provides the ultimate user comfort to access the vehicle. The user no longer needs to reach for any form of mechanical or electronic key to gain access to the vehicle. The vehicle recognizes an authorized user from others by the possession of

  6. The Passive Aggressive Conflict Cycle

    ERIC Educational Resources Information Center

    Whitson, Signe

    2013-01-01

    Understanding the Passive Aggressive Conflict Cycle (PACC) helps observers to be able to look beyond behavior and better understand what is occurring beneath the surface. This article presents a real-life example of a seemingly minor conflict between a teacher and child that elicited an apparent major overreaction by the adult. Also provided is a…

  7. Passivation Of High-Temperature Superconductors

    NASA Technical Reports Server (NTRS)

    Vasquez, Richard P.

    1991-01-01

    Surfaces of high-temperature superconductors passivated with native iodides, sulfides, or sulfates formed by chemical treatments after superconductors grown. Passivating compounds nearly insoluble in and unreactive with water and protect underlying superconductors from effects of moisture. Layers of cuprous iodide and of barium sulfate grown. Other candidate passivating surface films: iodides and sulfides of bismuth, strontium, and thallium. Other proposed techniques for formation of passivating layers include deposition and gas-phase reaction.

  8. Reliability assessment of passive safety systems

    Microsoft Academic Search

    L Burgazzi; GL Fiorini; F De Magistris; W Von Lensa; M Staat; J Altes

    1998-01-01

    Innovative reactor concepts make use of passive safety features to a large extent in combination with active safety or operational systems. Following the IAEA definitions a passive component does not need external input (especially energy) to operate. This is why it is expected that passive systems combine among others the advantages of simplicity, reduction of the need for human interaction,

  9. Development of Verbal Passive in Williams Syndrome

    ERIC Educational Resources Information Center

    Perovic, Alexandra; Wexler, Kenneth

    2010-01-01

    Purpose: To experimentally investigate knowledge of passives of actional ("hold") and psychological ("love") verbs in children with Williams syndrome (WS). Passives are usually reported to be in line with mental age in WS. However, studies usually focus on passives of actional verbs only. Method: Twenty-six children with WS, ages 6-16, and 3…

  10. Antenna for passive RFID tags

    NASA Astrophysics Data System (ADS)

    Schiopu, Paul; Manea, Adrian; Cristea, Ionica; Grosu, Neculai; Vladescu, Marian; Craciun, Anca-Ileana; Craciun, Alexandru

    2015-02-01

    Minuscule devices, called RFID tags are attached to objects and persons and emit information which positioned readers may capture wirelessly. Many methods of identification have been used, but that of most common is to use a unique serial number for identification of person or object. RFID tags can be characterized as either active or passive [1,2]. Traditional passive tags are typically in "sleep" state until awakened by the reader's emitted field. In passive tags, the reader's field acts to charge the capacitor that powers the badge and this can be a combination of antenna and barcodes obtained with SAW( Surface Acoustic Wave) devices [1,2,3] . The antenna in an RFID tag is a conductive element that permits the tag to exchange data with the reader. The paper contribution are targeted to antenna for passive RFID tags. The electromagnetic field generated by the reader is somehow oriented by the reader antenna and power is induced in the tag only if the orientation of the tag antenna is appropriate. A tag placed orthogonal to the reader yield field will not be read. This is the reason that guided manufacturers to build circular polarized antenna capable of propagating a field that is alternatively polarized on all planes passing on the diffusion axis. Passive RFID tags are operated at the UHF frequencies of 868MHz (Europe) and 915MHz (USA) and at the microwave frequencies of 2,45 GHz and 5,8 GHz . Because the tags are small dimensions, in paper, we present the possibility to use circular polarization microstrip antenna with fractal edge [2].

  11. Evaluation of Alternate Surface Passivation Methods (U)

    SciTech Connect

    Clark, E

    2005-05-31

    Stainless steel containers were assembled from parts passivated by four commercial vendors using three passivation methods. The performance of these containers in storing hydrogen isotope mixtures was evaluated by monitoring the composition of initially 50% H{sub 2} 50% D{sub 2} gas with time using mass spectroscopy. Commercial passivation by electropolishing appears to result in surfaces that do not catalyze hydrogen isotope exchange. This method of surface passivation shows promise for tritium service, and should be studied further and considered for use. On the other hand, nitric acid passivation and citric acid passivation may not result in surfaces that do not catalyze the isotope exchange reaction H{sub 2} + D{sub 2} {yields} 2HD. These methods should not be considered to replace the proprietary passivation processes of the two current vendors used at the Savannah River Site Tritium Facility.

  12. Passive oscillatory heat transport systems

    NASA Astrophysics Data System (ADS)

    Weislogel, Mark M.

    2002-01-01

    An underdeveloped class of oscillatory passive heat transport cycles are discussed that have the potential to transport significantly higher heat loads than current heat pipes. Prototype cycles employing inferior working fluids have demonstrated transport of higher heat loads over significantly greater distances than similarly sized heat pipes (including CPLs and LHPs) employing ammonia. Most of the proposed cycles do not require capillary forces to circulate the working fluid. They are also relatively insensitive to gravity and might best be compared to thermal systems using mechanical pumps. The history of development to date of such cycles is presented in relation to other approaches under consideration for various semi/passive thermal control applications. Specific operational characteristics of a select loop are presented. The obvious pros and cons of these systems are discussed as well as potential applications-particularly as regards electronics cooling. .

  13. Passive Photonic Devices in Glass

    NASA Astrophysics Data System (ADS)

    Eaton, Shane M.; Herman, Peter R.

    Femtosecond laser microfabrication offers the potential for writing passive photonic circuits inside bulk glasses, for use in last-mile photonic networks, sensing, and lab-on-a-chip applications. In this chapter, the fabrication methods for writing low-loss optical waveguides along with waveguide and device characterization techniques are reviewed. The advantages and disadvantages of femtosecond laser writing are analyzed and compared with existing planar lithographic fabrication techniques.

  14. Active and passive fields in turbulent transport: the role of statistically preserved structures.

    PubMed

    Ching, Emily S C; Cohen, Yoram; Gilbert, Thomas; Procaccia, Itamar

    2003-01-01

    We have recently proposed that the statistics of active fields (which affect the velocity field itself) in well-developed turbulence are also dominated by the statistically preserved structures of auxiliary passive fields which are advected by the same velocity field. The statistically preserved structures are eigenmodes of eigenvalue 1 of an appropriate propagator of the decaying (unforced) passive field, or equivalently, the zero modes of a related operator. In this paper we investigate further this surprising finding via two examples of shell models, one akin to turbulent convection in which the temperature is the active scalar, and the other akin to magnetohydrodynamics in which the magnetic field is the active vector. In the first example, all the even correlation functions of the active and passive fields exhibit identical scaling behavior. The second example appears at first sight to be a counterexample: the statistical objects of the active and passive fields have entirely different scaling exponents. We demonstrate, nevertheless, that the statistically preserved structures of the passive vector dominate again the statistics of the active field, except that due to a dynamical conservation law the amplitude of the leading zero mode cancels exactly. The active vector is then dominated by the subleading zero mode of the passive vector. Our work thus suggests that the statistical properties of active fields in turbulence can be understood with the same generality as those of passive fields. PMID:12636599

  15. A passive sampler for ambient gaseous oxidized mercury concentrations

    NASA Astrophysics Data System (ADS)

    Lyman, Seth N.; Gustin, Mae S.; Prestbo, Eric M.

    2010-01-01

    This paper reports on the development of a passive sampler for estimating gaseous oxidized mercury concentrations. Atmospheric gaseous oxidized mercury concentrations calculated from passive sampler data were correlated with those obtained using an automated analyzer ( r2 = 0.71, p < 0.01, n = 110 for one-week deployments; r2 = 0.89, p < 0.01, n = 22 for two-week deployments). Sampler uptake was not significantly affected by changes in temperature, humidity, or ozone concentration, but it was slightly dependent on wind speed. As such, an equation for correcting data due to this factor was developed based on wind tunnel and field data. The detection limit for a two-week sampler deployment was ˜5 pg m -3. Field data collected in Nevada and the southeastern United States showed these samplers are useful for investigating spatial and temporal variability in gaseous oxidized mercury concentrations.

  16. Cellular automaton formulation of passive scalar dynamics

    NASA Technical Reports Server (NTRS)

    Chen, Hudong; Matthaeus, William H.

    1987-01-01

    Cellular automata modeling of the advection of a passive scalar in a two-dimensional flow is examined in the context of discrete lattice kinetic theory. It is shown that if the passive scalar is represented by tagging or 'coloring' automation particles a passive advection-diffusion equation emerges without use of perturbation expansions. For the specific case of the hydrodynamic lattice gas model of Frisch et al. (1986), the diffusion coefficient is calculated by perturbation.

  17. Accumulation of polycyclic aromatic hydrocarbons by lichen transplants: Comparison with gas-phase passive air samplers.

    PubMed

    Loppi, S; Pozo, K; Estellano, V H; Corsolini, S; Sardella, G; Paoli, L

    2015-09-01

    This study compared the accumulation of 16 polycyclic aromatic hydrocarbons (PAHs) in samples of the lichen Evernia prunastri exposed for 3months in and around an industrial area of S Italy with that in co-located passive gas-phase air samplers. The results showed a strong linear correlations (R=0.96, P<0.05) between total PAHs in lichens and in passive samplers, clearly indicating that lichen transplants may provide direct quantitative information on the atmospheric load by total PAHs, allowing translation of lichen values into atmospheric concentrations. To the best of our knowledge this is the first study reporting such a correlation with gas-phase passive air samplers. PMID:25911045

  18. Passive cavitation imaging with ultrasound arrays

    PubMed Central

    Salgaonkar, Vasant A.; Datta, Saurabh; Holland, Christy K.; Mast, T. Douglas

    2009-01-01

    A method is presented for passive imaging of cavitational acoustic emissions using an ultrasound array, with potential application in real-time monitoring of ultrasound ablation. To create such images, microbubble emissions were passively sensed by an imaging array and dynamically focused at multiple depths. In this paper, an analytic expression for a passive image is obtained by solving the Rayleigh–Sommerfield integral, under the Fresnel approximation, and passive images were simulated. A 192-element array was used to create passive images, in real time, from 520-kHz ultrasound scattered by a 1-mm steel wire. Azimuthal positions of this target were accurately estimated from the passive images. Next, stable and inertial cavitation was passively imaged in saline solution sonicated at 520 kHz. Bubble clusters formed in the saline samples were consistently located on both passive images and B-scans. Passive images were also created using broadband emissions from bovine liver sonicated at 2.2 MHz. Agreement was found between the images and source beam shape, indicating an ability to map therapeutic ultrasound beams in situ. The relation between these broadband emissions, sonication amplitude, and exposure conditions are discussed. PMID:20000921

  19. Passive tamper-indicating secure container

    SciTech Connect

    Bartberger, J.C.

    1993-07-01

    This paper describes a passive tamper-indicating secure container that has been designed to demonstrate concepts, features, and materials that can be used in passive container applications. (In a passive security system, physical phenomena provide visual indication of tampering.) The basic container {open_quotes}volume within a volume{close_quotes} assembly consists of a transparent plastic outer container and an aluminum inner container. Both containers incorporate passive, fingerprinted layers as part of the tamper-indicating container system. Many of the tamper-indicating features can be visually inspected without disassembling the container. The status of container development and potential applications for the container are addressed.

  20. General Corrosion and Passive Film Stability

    SciTech Connect

    Orme, C; Gray, J; Hayes, J; Wong, L; Rebak, R; Carroll, S; Harper, J; Gdowski, G

    2005-07-19

    This report summarizes both general corrosion of Alloy 22 from 60 to 220 C and the stability of the passive (oxide) film from 60 to 90 C over a range of solution compositions that are relevant to the in-drift chemical environment at the waste package surface. The general corrosion rates were determined by weight-loss measurements in a range of complex solution compositions representing the products of both the evaporation of seepage water and also the deliquescence of dust previously deposited on the waste canisters. These data represent the first weight-loss measurements performed by the program at temperatures above 90 C. The low corrosion rates of Alloy 22 are attributed to the protective oxide film that forms at the metal surface. In this report, changes in the oxide film composition are correlated with weight loss at the higher temperatures (140-220 C) where film characterization had not been previously performed. The stability of the oxide film was further analyzed by conducting a series of electrochemical tests in progressively more acidic solutions to measure the general corrosion rates in solutions that mimic crevice or pit environments.

  1. Cretaceous sequence stratigraphy of the Northern South American Passive Margin: Implications for tectonic evolution

    SciTech Connect

    Kauffman, E.G.; Villamil, T.; Johnson, C.C. (Univ. of Colorado, Boulder, CO (United States))

    1993-02-01

    The passive margin of northern South America, from Colombia to northeastern Venezuela, was relatively stable through the Cretaceous and only broadly affected by the entry of the Caribbean Plate into the Protocaribbean Basin. This region offers a unique opportunity to test the relative effects of global sealevel change, autocyclic sedimentologic processed, and regional tectonics in shaping the stratigraphic record of Cretaceous passive margins. High-resolution stratigraphic studies of Colombia and Venezuela have established a precise system of regional chronology and correlation with resolution <1 Ma (50-500 ka for the middle Cretaceous). This allows precise separation of allocyclic and autocyclic controls on facies development. This new chronology integrates assemblage zone biostratigraphy with event/cycle chronostratigraphy. Newly measured Cretaceous sections in Venezuela and throughout Colombia are calibrated to this new chronology, and sequence stratigraphic units independently defined to the third-order of resolution. Graphic correlation of all sections is used to identify sequences with regional stratigraphic expression, and those which correlate to sequence stratigraphic standards of North America, Europe and the global cycles of Hag et al. (1988). 50-60 percent of the stratigraphic sequences across the South American passive margin correlate to other continents and to the global sequence stratigraphic standard, reflecting strong eustatic influence on Cretaceous sedimentation across northern South America. The remaining sequences in this region reflect tectonic modification of the passive margin and autocyclic sedimentary processes.

  2. Auto-aligning and splicing PM-fibers of different types with a passive method

    Microsoft Academic Search

    Wenxin Zheng

    1996-01-01

    Many different types of polarization maintaining (PM) fibers and polarizing (PZ) fibers are playing important roles in most of fiber optical gyros and high speed communication networks. A new method for passively aligning and fusion- splicing those fiber types are developed with the help of the lens-effect tracing technique. Instead of calculating the correlation directly between the two POL profiles

  3. Terrain data aided passive ground target tracking

    Microsoft Academic Search

    Chang-Hwan Kim; Keeyoung Choi; Chang-Kyung Ryoo; Kyeong-Dae Park; Jin-Bok Kim; Ki-Sung Kim; Jong-Lae Jo

    2009-01-01

    The primary purpose of passive tracking function is to support weapon systems on the military aircraft. A ground-attacking aircraft must know the precise location of the target to fulfill its missions. The target tracking system must estimate location of the target passively, if the need of stealth performance is highly required. A target is designated using integrated sensors, such as

  4. Passive Safety Features for Small Modular Reactors

    Microsoft Academic Search

    Daniel T

    2010-01-01

    The rapid growth in the size and complexity of commercial nuclear power plants in the 1970s spawned an interest in smaller, simpler designs that are inherently or intrinsically safe through the use of passive design features. Several designs were developed, but none were ever built, although some of their passive safety features were incorporated into large commercial plant designs that

  5. Bond Graph Based Approach to Passive Teleoperation

    E-print Network

    Li, Perry Y.

    in which the coordination control approximates the hydraulic system by its kinematic behavior been directed toward developing passive hydraulic systems 7­11 . To enable the passivity analysis-port systems a command port and a hydraulic port with respect to the total scaled power input have been

  6. Passive Thermal Management of Foil Bearings

    NASA Technical Reports Server (NTRS)

    Bruckner, Robert J. (Inventor)

    2015-01-01

    Systems and methods for passive thermal management of foil bearing systems are disclosed herein. The flow of the hydrodynamic film across the surface of bearing compliant foils may be disrupted to provide passive cooling and to improve the performance and reliability of the foil bearing system.

  7. Passive ice freezing-releasing heat pipe

    DOEpatents

    Gorski, Anthony J. (Lemont, IL); Schertz, William W. (Batavia, IL)

    1982-01-01

    A heat pipe device has been developed which permits completely passive ice formation and periodic release of ice without requiring the ambient temperature to rise above the melting point of water. This passive design enables the maximum amount of cooling capacity to be stored in the tank.

  8. Passive radar in the high frequency band

    Microsoft Academic Search

    Giuseppe Fabrizio; Fabiola Colone; Pierfrancesco Lombardo; Alfonso Farina

    2008-01-01

    Passive radar systems using emitters of opportunity for target detection and tracking have received significant interest recently, especially those which exploit frequency modulated (FM) radio stations and TV transmitters as signal sources. This paper is concerned with passive radar systems that utilize signal sources in the high frequency (HF) band (3-30 MHz), where due to long-distance ionospheric propagation, the transmitter

  9. Passive sensor systems for nuclear material monitoring

    Microsoft Academic Search

    M. L. Simpson; L. A. Boatner; D. E. Holcomb; S. A. McElhaney; J. T. Mihalczo; J. D. Muhs; M. R. Roberts; N. W. Hill

    1993-01-01

    Passive fiber optic sensor systems capable of confirming the presence of special nuclear materials in storage or process facilities are being developed at Oak Ridge National Laboratory (ORNL). These sensors provide completely passive, remote measurement capability. No power supplies, amplifiers, or other active components that could degrade system reliability are required at the sensor location. ORNL, through its research programs

  10. Passive Solar Construction--Design and Performance.

    ERIC Educational Resources Information Center

    Conservation and Renewable Energy Inquiry and Referral Service (DOE), Silver Spring, MD.

    Presented is a list of books and reports intended to serve as technical sources of information for the building professional interested in energy conservation. These publications are grouped under these headings: (1) energy-conserving building design; (2) passive systems/design; (3) passive systems/performance; and (4) proceedings (of the American…

  11. The German Passive: Analysis and Teaching Technique.

    ERIC Educational Resources Information Center

    Griffen, T. D.

    1981-01-01

    Proposes an analysis of German passive based upon internal structure rather than translation conventions from Latin and Greek. Claims that this approach leads to a description of the perfect participle as an adjectival complement, which eliminates the classification of a passive voice for German and simplifies the learning task. (MES)

  12. EVALUATION OF PASSIVE SAMPLING DEVICES (PSDS)

    EPA Science Inventory

    The basic objectives of this study were to evaluate the performance of the EPA passive sampling device (PSD) for sampling of ambient level volatile organic compounds (VOC's); to develop an understanding of the mechanics of passive sampling using reversible adsorption; and to appl...

  13. Visuomotor learning by passive motor experience

    PubMed Central

    Sakamoto, Takashi; Kondo, Toshiyuki

    2015-01-01

    Humans can adapt to unfamiliar dynamic and/or kinematic transformations through the active motor experience. Recent studies of neurorehabilitation using robots or brain-computer interface (BCI) technology suggest that passive motor experience would play a measurable role in motor recovery, however our knowledge of passive motor learning is limited. To clarify the effects of passive motor experience on human motor learning, we performed arm reaching experiments guided by a robotic manipulandum. The results showed that the passive motor experience had an anterograde transfer effect on the subsequent motor execution, whereas no retrograde interference was confirmed in the ABA paradigm experiment. This suggests that the passive experience of the error between visual and proprioceptive sensations leads to the limited but actual compensation of behavior, although it is fragile and cannot be consolidated as a persistent motor memory. PMID:26029091

  14. Effectiveness of passivation techniques on hydrogen desorption in a tritium environment

    NASA Astrophysics Data System (ADS)

    Woodall, Steven Michael

    2009-11-01

    Tritium is a radioactive isotope of hydrogen. It is used as a fuel in fusion reactors, a booster material in nuclear weapons and as a light source in commercial applications. When tritium is used in fusion reactors, and especially when used in the manufacture of nuclear weapons, purity is critical. For U.S. Department of Energy use, tritium is recycled by Savannah River Site in South Carolina and is processed to a minimum purity of 99.5%. For use elsewhere in the country, it must be shipped and stored, while maintaining the highest purity possible. As an isotope of hydrogen it exchanges easily with the most common isotope of hydrogen, protium. Stainless steel bottles are used to transport and store tritium. Protium, present in air, becomes associated in and on the surface of stainless steel during and after the manufacture of the steel. When filled, the tritium within the bottle exchanges with the protium in and on the surface of the stainless steel, slowly contaminating the pure tritium with protium. The stainless steel is therefore passivated to minimize the protium outgrowth of the bottles into the pure tritium. This research is to determine how effective different passivation techniques are in minimizing the contamination of tritium with protium. Additionally, this research will attempt to determine a relationship between surface chemistry of passivated steels and protium contamination of tritium. The conclusions of this research found that passivated bottles by two companies which routinely provide passivated materials to the US Department of Energy provide low levels of protium outgrowth into pure tritium. A bottle passivated with a material to prevent excessive corrosion in a highly corrosive environment, and a clean and polished bottle provided outgrowth rates roughly twice those of the passivated bottles above. Beyond generally high levels of chromium, oxygen, iron and nickel in the passivated bottles, there did not appear to be a strong correlation between surface chemistry in the surface of the bottles and protium outgrowth rates.

  15. Passive Tracking System and Method

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Ngo, Phong H. (Inventor); Chen, Henry A. (Inventor); Phan, Chau T. (Inventor); Bourgeois, Brian A. (Inventor); Dusl, John (Inventor); Hill, Brent W. (Inventor)

    2005-01-01

    System and methods are disclosed for passively determining the location of a moveable transmitter utilizing a pair of phase shifts at a receiver for extracting a direction vector from a receiver to the transmitter. In a preferred embodiment, a phase difference between the transmitter and receiver is extracted utilizing a noncoherent demodulator in the receiver. The receiver includes antenna array with three antenna elements, which preferably are patch antenna elements placed apart by one-half wavelength. Three receiver channels are preferably utilized for simultaneously processing the received signal from each of the three antenna elements. Multipath transmission paths for each of the three receiver channels are indexed so that comparisons of the same multipath component are made for each of the three receiver channels. The phase difference for each received signal is determined by comparing only the magnitudes of received and stored modulation signals to determine a winning modulation symbol.

  16. Passive States for Essential Observers

    E-print Network

    Robert Strich

    2008-01-23

    The aim of this note is to present a unified approach to the results given in \\cite{bb99} and \\cite{bs04} which also covers examples of models not presented in these two papers (e.g. $d$-dimensional Minkowski space-time for $d\\geq 3$). Assuming that a state is passive for an observer travelling along certain (essential) worldlines, we show that this state is invariant under the isometry group, is a KMS-state for the observer at a temperature uniquely determined by the structure constants of the Lie algebra involved and fulfills (a variant of) the Reeh-Schlieder property. Also the modular objects associated to such a state and the observable algebra of an observer are computed and a version of weak locality is examined.

  17. Passive Tracking System and Method

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Ngo, Phong H. (Inventor); Chen, Henry A. (Inventor); Phan, Chau T. (Inventor); Bourgeois, Brian A. (Inventor); Dusl, Jon (Inventor); Hill, Brent W. (Inventor)

    2003-01-01

    Systems and methods are disclosed for passively determining the location of a moveable transmitter utilizing a pair of phase shifts at a receiver for extracting a direction vector from a receiver to the transmitter. In a preferred embodiment, a phase difference between the transmitter and receiver is extracted utilizing a noncoherent demodulator in the receiver. The receiver includes an antenna array with three antenna elements, which preferably are patch antenna elements spaced apart by one-half wavelength. Three receiver channels are preferably utilized for simultaneously processing the received signal from each of the three antenna elements. Multipath transmission paths for each of the three receiver channels are indexed so that comparisons of the same multipath component are made for each of the three receiver channels. The phase difference for each received signal is determined by comparing only the magnitudes of received and stored modulation signals to determine a winning modulation symbol.

  18. A Passive Magnetic Bearing Flywheel

    NASA Technical Reports Server (NTRS)

    Siebert, Mark; Ebihara, Ben; Jansen, Ralph; Fusaro, Robert L.; Morales, Wilfredo; Kascak, Albert; Kenny, Andrew

    2002-01-01

    A 100 percent passive magnetic bearing flywheel rig employing no active control components was designed, constructed, and tested. The suspension clothe rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm, which is 65 percent above the first critical speed of 3336 rpm. Operation was not continued beyond this point because of the excessive noise generated by the air impeller and because of inadequate containment in case of failure. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  19. Citric Acid Passivation of Stainless Steel

    NASA Technical Reports Server (NTRS)

    Yasensky, David; Reali, John; Larson, Chris; Carl, Chad

    2009-01-01

    Passivation is a process for cleaning and providing corrosion protection for stainless steel. Currently, on Kennedy Space Center (KSC), only parts passivated with nitric acid are acceptable for use. KSC disposes of approximately 125gal of concentrated nitric acid per year, and receives many parts from vendors who must also dispose of used nitric acid. Unfortunately, nitric acid presents health and environmental hazards. As a result, several recent industry studies have examined citric acid as an alternative. Implementing a citric acid-based passivation procedure would improve the health and environmental safety aspects of passivation process. However although there is a lack of published studies that conclusively prove citric acid is a technically sound passivation agent. In 2007, NASA's KSC Materials Advisory Working Group requested the evaluation of citric acid in place of nitric acid for passivation of parts at KSC. United Space Alliance Materials & Processes engineers have developed a three-phase test plan to evaluate citric acid as an alternative to nitric acid on three stainless steels commonly used at KSC: UNS S30400, S41000, and S17400. Phases 1 and 2 will produce an optimized citric acid treatment based on results from atmospheric exposure at NASA's Beach Corrosion Facility. Phase 3 will compare the optimized solution(s) with nitric acid treatments. If the results indicate that citric acid passivates as well or better than nitric acid, NASA intends to approve this method for parts used at the Kennedy Space Center.

  20. New assistive technology for passive standing.

    PubMed

    Gear, A J; Suber, F; Neal, J G; Nguyen, W D; Edlich, R F

    1999-01-01

    The anesthetic skin of patients with spinal cord injuries makes these patients a high-risk population for burn injuries. Innovations in rehabilitation engineering can now provide the disabled with mechanical devices that allow for passive standing. Passive standing has been shown to counteract many of the effects of chronic immobilization and spinal cord injury, including bone demineralization, urinary calculi, cardiovascular instability, and reduced joint range of motion and muscular tone. This article will describe several unique assistive devices that allow for passive standing and an improvement in daily living for people with disabilities. PMID:10188115

  1. Passive tick surveillance, dog seropositivity, and incidence of human Lyme disease

    USGS Publications Warehouse

    Johnson, J.L.; Ginsberg, H.S.; Zhioua, E.; Whitworth, U.G., Jr.; Markowski, D.; Hyland, K.E.; Hu, R.

    2004-01-01

    Data on nymphal Ixodes scapularis ticks submitted by the public to the University of Rhode Island Tick Research Laboratory for testing from 1991 to 2000 were compared with human case data from the Rhode Island Department of Health to determine the efficacy of passive tick surveillance at assessing human risk of Lyme disease. Numbers of ticks submitted were highly correlated with human cases by county (r = 0.998, n = 5 counties) and by town (r = 0.916, n = 37 towns), as were the numbers of positive ticks submitted (r = 0.989 by county, r = 0.787 by town). Human cases were correlated with ticks submitted by town each year, and with positive ticks in all but 2 years. Thus, passive tick surveillance effectively assessed geographical risk of human Lyme disease. In contrast, tick submissions through time were not correlated with human cases from year to year. Dog seropositivity was significantly correlated with human cases by county in both years tested, but by town in only one of two years. Numbers of ticks submitted were correlated with dog seropositivity by county but not by town, apparently because of high variability among towns with small sample sizes. Our results suggest that passive tick surveillance, using ticks submitted by the public for Lyme spirochete testing, can be used to assess the geographical distribution of Lyme disease risk, but cannot reliably predict Lyme incidence from year to year.

  2. Passive acoustics as a monitoring tool for evaluating oyster reef restoration

    NASA Astrophysics Data System (ADS)

    Zenil Becerra, Hilde P.

    Oyster reefs are biodiverse communities that provide many ecological and commercial benefits. However, oyster reefs have declined around the world from human activities. Oyster reef restoration programs have begun to limit some of the decline, but the need for determining the success of a program has been problematic. Passive acoustic techniques can use naturally occurring sounds produced by organisms to assess biodiversity. Passive acoustics was utilized to compare the sounds in natural and restored oyster reefs, with special attention on snapping shrimp (Alpheus spp.) snap sounds, in the St. Lucie Estuary, Florida over a one year period. Season, estuary region, habitat and day period had an effect on sound production Passive acoustic monitoring of snapping shrimp sound production may be a useful non-destructive technique for monitoring the progress of oyster reef restoration projects once further correlations are established between environmental effects and sound production.

  3. Passive solar roof ice melter

    SciTech Connect

    Deutz, R.T.

    1981-09-29

    An elongated passive solar roof ice melter is placed on top of accumulated ice and snow including an ice dam along the lower edge of a roof of a heated building and is held against longitudinal movement with respect to itself. The melter includes a bottom wall having an upper surface highly absorbent to radiant solar energy; a first window situated at right angles with respect to the bottom wall, and a reflecting wall connecting the opposite side edges of the bottom wall and the first window. The reflecting wall has a surface facing the bottom wall and the window which is highly reflective to radiant solar energy. Radiant solar energy passes through the first window and either strikes the highly absorbent upper surface of the bottom wall or first strikes the reflecting wall to be reflected down to the upper surface of the bottom wall. The heat generated thereby melts through the ice below the bottom wall causing the ice dam to be removed between the bottom wall and the top of the roof and immediately adjacent to the ice melter along the roof. Water dammed up by the ice dam can then flow down through this break in the dam and drain out harmlessly onto the ground. This prevents dammed water from seeping back under the shingles and into the house to damage the interior of the house.

  4. Remote electrically passive position transducer

    NASA Astrophysics Data System (ADS)

    Ducharme, Alfred D.; Markos, Constantine T.; Rieder, R. J.; Wijntjes, Geert J.

    1999-02-01

    We will report on the design and testing of a precision, remote, via fiber optics position transducer suitable for incorporation in a closed loop fly-by-light positioning system. The design is based on Visidyne developed technology for an ultra high resolution optical radar based on Continuous Wave modulated light at a frequency of 1 GHz. It produces digital position data with 12 bit precision e.g., for a travel distance, stroke of 6 inches or greater at a bandwidth, update rate of 1 KHz. The passive nature of the transducer at the actuator location and the high operating frequency makes it highly tolerant to even extreme levels of Electro Magnetic Interference and when constructed from high temperature material is can operate at temperatures well in excess of 300 degrees C. We will discuss transducer performance, precision and position stability with particular emphasis on the effects of length changes within the multi-mode optical fibers used to deliver and collect the light to and from the transducer. We will also discuss cost aspects of the design and their effect on overcoming market entry barriers.

  5. [Passive euthanasia and living will].

    PubMed

    Julesz, Máté

    2014-07-01

    This article deals with the intentional distinction between murder of first degree and passive euthanasia. In Hungary, active euthanasia is considered to be a murder of first degree, whilst the Netherlands, Belgium, Luxemburg and Switzerland have legalized the active form of mercy killing in Europe. The palliative terminal care, when e.g. giving pain-killer morphine to the patient, might result in decreasing the patient's life-span, and thus causing indirect euthanasia. However, the legal institution of living will exists in several counter-euthanasia countries. The living will allows future patients to express their decision in advance to refuse a life-sustaining treatment, e.g. in case of irreversible coma. The institution of living will exists in Germany and in Hungary too. Nevertheless, the formal criteria of living will make it hardly applicable. The patient ought to express his/her will before a notary public in advance, and he/she should hand it over when being hospitalized. If the patient is not able to present his/her living will to his/her doctor in the hospital, then his/her only hope remains that he/she has given a copy of the living will to the family doctor previously, and the family doctor will notify the hospital. PMID:24974840

  6. The Future of Passive Solar in Industry 

    E-print Network

    Wulfinghoff, D. R.

    1985-01-01

    Passive solar is a family of techniques for the direct use of sunlight for illumination and heating. Industrial facilities have characteristics which particularly favor the use of these techniques. This paper examines the applicability and economic...

  7. Defeating passive eavesdropping with quantum illumination

    E-print Network

    Shapiro, Jeffrey H.

    A two-way protocol for defeating passive eavesdropping is proposed. For each information bit, Alice sends Bob T sec of signal-beam output from a spontaneous parametric down-converter over a pure-loss channel while retaining ...

  8. Passive Limitations for a Magnetic Gravity Compensator

    NASA Astrophysics Data System (ADS)

    Janssen, Jeroen L. G.; Paulides, Johannes J. H.; Lomonova, Elena A.

    The development of sophisticated advanced vibration isolation is important because even the minutest vibrations have disastrous effects on the performance of static and moving parts in high-precision machines. This paper concerns with the isolation of these vibrations for a large static body in an advanced micro-lithographic system, where a passive/active electromagnetic solution is presented. In these configurations passive permanent magnets (PM) provide the gravity compensation and active electromagnets the accurate positioning. This paper only considers the applicability of a passive magnetic solution for this high force gravity compensation application, or, more specifically, the influence of various PM array topologies on the force density. Further, fast-solving analytical models are presented and consequently are used to illustrate the feasibility of using passive permanent magnets for gravity compensation in this demanding high precision industrial application.

  9. Passive machine augmented composite for multifunctional properties 

    E-print Network

    Kim, Jong Hyun

    2005-11-01

    This dissertation studies by experiment and numerical analysis an advanced composite material (Machine Augmented Composite or MAC) for enhancement of the passive damping while maintaining its stiffness. This MAC is composed of a pre-buckled wall...

  10. The Soil Moisture Active Passive (SMAP) Mission

    E-print Network

    Entekhabi, Dara

    The Soil Moisture Active Passive (SMAP) mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council's Decadal Survey. SMAP will make global measurements of ...

  11. Influence and Passivity in Social Media

    E-print Network

    Romero, Daniel M; Asur, Sitaram; Huberman, Bernardo A

    2010-01-01

    The ever-increasing amount of information flowing through Social Media forces the members of these networks to compete for attention and influence by relying on other people to spread their message. A large study of information propagation within Twitter reveals that the majority of users act as passive information consumers and do not forward the content to the network. Therefore, in order for individuals to become influential they must not only obtain attention and thus be popular, but also overcome user passivity. We propose an algorithm that determines the influence and passivity of users based on their information forwarding activity. An evaluation performed with a 2.5 million user dataset shows that our influence measure is a good predictor of URL clicks, outperforming several other measures that do not explicitly take user passivity into account. We also explicitly demonstrate that high popularity does not necessarily imply high influence and vice-versa.

  12. PRIMA: passive reduced-order interconnect macromodeling algorithm

    Microsoft Academic Search

    Altan Odabasioglu; Mustafa Celik; Lawrence T. Pileggi

    1997-01-01

    This paper describes PRIMA, an algorithm for generating provably passive reduced order N-port models for RLC interconnect circuits. It is demonstrated that, in addition to requiring macromodel stability, macromodel passivity is needed to guarantee the overall circuit stability once the active and passive driver\\/load models are connected. PRIMA extends the block Arnoldi technique to include guaranteed passivity. Moreover, it is

  13. Detailed study of the composition of hydrogenated SiNx layers for high-quality silicon surface passivation

    NASA Astrophysics Data System (ADS)

    Mackel, H.; Ludemann, R.

    2002-09-01

    We have analyzed the role of the bond densities of a-SiNx:H films on the passivation properties at the SiNx:H/Si interface. The films are deposited onto silicon wafers by plasma enhanced chemical vapor deposition using a 13.56 MHz direct plasma system and a SiH4/N2/H2 gas mixture. Fourier transform infrared spectroscopy measurements are performed in order to obtain the bonding concentration of Si-Si, Si-H, Si-N and N-H. The passivation properties are deduced by lifetime measurements using a microwave-detected photoconductance decay technique. Carrier lifetimes of the SiNx:H-passivated silicon wafers of up to 1200 mus correlate to surface recombination velocities, Seff, as low as 4-6 cm/s. This means that the films provide excellent passivation of silicon surfaces, which is necessary for high-efficiency solar cells. The Si-H bond density and the total bond density are considered as measures of the passivation quality. Models for the formation of K+ centers and for the passivation pathways during the plasma deposition are proposed. The addition of a further hydrogen source to the plasma gas (H2) leads to a better defect passivation of Si dangling bonds during the deposition.

  14. CWDM passive components fabricated by FBT technology

    NASA Astrophysics Data System (ADS)

    You, Shanhong; Li, Xinwan; Yin, Zongmin; Zeng, QingJi; Cui, Huaijun; Jiang, Yongjun

    2002-07-01

    In this paper, the process of fabricating coarse wavelength division multiplexing (CWDM) passive components using Fused Biconic Taper (FBT) technology is introduced. The performances and specifications of CWDM passive components are measured and reported. And we compare the performances and cost of this kind of CWDM module with the performances and cost of CWDM module based on thin-film-filter technology and dense wavelength division multiplexing (DWDM) module.

  15. Energy savings obtainable through passive solar techniques

    SciTech Connect

    Balcomb, J.D.

    1980-01-01

    A passive solar energy system is one in which the thermal energy flow is by natural means, that is by radiation, conduction, or natural convection. The purpose of the paper is to provide a survey of passive solar heating experience, especially in the US. Design approaches are reviewed and examples shown. Misconceptions are discussed. Advantages are listed. The Los Alamos program of performance simulation and evaluation is described and a simplified method of performance estimation is outlined.

  16. Antimony Passivation of InP

    Microsoft Academic Search

    Hajime Nobusawa; Hideaki Ikoma

    1993-01-01

    Antimony passivation of InP was investigated. Sb was evaporated on a HCl-etched InP substrate and annealed at 300°C for 10 min. I--V characteristics of the Au\\/Sb\\/InP diode are substantially improved and the Schottky barrier height becomes higher as compared with the conventional Au\\/InP diode. The reverse current decreases by about two orders of magnitude upon Sb passivation. X-ray photoelectron spectroscopic

  17. A Better Approach to Passive Microphone Splitting

    Microsoft Academic Search

    Jim Brown; Bill Whitlock

    While there are clear technical advantages to active microphone splitting, operational considerations dictate the use of passive splitting of microphones in most sound reinforcement applications. Modern microphones generally re- quire a load impedance greater than 1,000 ohms, and performance often degrades significantly with heavier loading. Since mix desk input impedances rarely exceed 1,500 ohms, passive splitting utilizing 1:1 turns ratio

  18. Passive Safety Features for Small Modular Reactors

    SciTech Connect

    Ingersoll, Daniel T [ORNL] [ORNL

    2010-01-01

    The rapid growth in the size and complexity of commercial nuclear power plants in the 1970s spawned an interest in smaller, simpler designs that are inherently or intrinsically safe through the use of passive design features. Several designs were developed, but none were ever built, although some of their passive safety features were incorporated into large commercial plant designs that are being planned or built today. In recent years, several reactor vendors are actively redeveloping small modular reactor (SMR) designs with even greater use of passive features. Several designs incorporate the ultimate in passive safety they completely eliminate specific accident initiators from the design. Other design features help to reduce the likelihood of an accident or help to mitigate the accident s consequences, should one occur. While some passive safety features are common to most SMR designs, irrespective of the coolant technology, other features are specific to water, gas, or liquid-metal cooled SMR designs. The extensive use of passive safety features in SMRs promise to make these plants highly robust, protecting both the general public and the owner/investor. Once demonstrated, these plants should allow nuclear power to be used confidently for a broader range of customers and applications than will be possible with large plants alone.

  19. A new method to inverse soil moisture based on thermal infrared and passive microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Zhou, Zhuang; Kou, Xiaokang; Zhao, Shaojie; Jiang, Lingmei

    2014-11-01

    Soil moisture is one of the main factors in the water, energy and carbon cycles. It constitutes a major uncertainty in climate and hydrological models. By now, passive microwave remote sensing and thermal infrared remote sensing technology have been used to obtain and monitor soil moisture. However, as the resolution of passive microwave remote sensing is very low and the thermal infrared remote sensing method fails to provide soil temperature on cloudy days, it is hard to monitor the soil moisture accurately. To solve the problem, a new method has been tried in this research. Thermal infrared remote sensing and passive microwave remote sensing technology have been combined based on the delicate experiment. Since the soil moisture retrieved by passive microwave in general represents surface centimeters deep, which is different from deeper soil moisture estimated by thermal inertia method, a relationship between the two depths soil moisture has been established based on the experiment. The results show that there is a good relationship between the soil moisture estimated by passive microwave and thermal infrared remote sensing method. The correlation coefficient is 0.78 and RMSE (root mean square error) is 0.0195 · ?. This research provides a new possible method to inverse soil moisture.

  20. Superadditive correlation

    NASA Astrophysics Data System (ADS)

    Giraud, B. G.; Heumann, John M.; Lapedes, Alan S.

    1999-05-01

    The fact that correlation does not imply causation is well known. Correlation between variables at two sites does not imply that the two sites directly interact, because, e.g., correlation between distant sites may be induced by chaining of correlation between a set of intervening, directly interacting sites. Such ``noncausal correlation'' is well understood in statistical physics: an example is long-range order in spin systems, where spins which have only short-range direct interactions, e.g., the Ising model, display correlation at a distance. It is less well recognized that such long-range ``noncausal'' correlations can in fact be stronger than the magnitude of any causal correlation induced by direct interactions. We call this phenomenon superadditive correlation (SAC). We demonstrate this counterintuitive phenomenon by explicit examples in (i) a model spin system and (ii) a model continuous variable system, where both models are such that two variables have multiple intervening pathways of indirect interaction. We apply the technique known as decimation to explain SAC as an additive, constructive interference phenomenon between the multiple pathways of indirect interaction. We also explain the effect using a definition of the collective mode describing the intervening spin variables. Finally, we show that the SAC effect is mirrored in information theory, and is true for mutual information measures in addition to correlation measures. Generic complex systems typically exhibit multiple pathways of indirect interaction, making SAC a potentially widespread phenomenon. This affects, e.g., attempts to deduce interactions by examination of correlations, as well as, e.g., hierarchical approximation methods for multivariate probability distributions, which introduce parameters based on successive orders of correlation.

  1. Dynamic correlation

    Microsoft Academic Search

    ARON J. COHEN; NICHOLAS C. HANDY

    2001-01-01

    From a knowledge of the Hartree-Fock and exact non-relativistic energies of atoms, the correlation energy Ec, as defined by Lowdin, may be calculated. For atoms this correlation is defined as dynamic correlation. The separate like-spin and unlike-spin contributions, Ec??, Ec??, may be calculated as a sum of pair energies from quantum chemistry; we have used the unrestricted Møller-Plesset second-order algorithm,

  2. Mesoscopics of ultrasound and seismic waves: application to passive imaging

    NASA Astrophysics Data System (ADS)

    Larose, É.

    2006-05-01

    This manuscript deals with different aspects of the propagation of acoustic and seismic waves in heterogeneous media, both simply and multiply scattering ones. After a short introduction on conventional imaging techniques, we describe two observations that demonstrate the presence of multiple scattering in seismic records: the equipartition principle, and the coherent backscattering effect (Chap. 2). Multiple scattering is related to the mesoscopic nature of seismic and acoustic waves, and is a strong limitation for conventional techniques like medical or seismic imaging. In the following part of the manuscript (Chaps. 3 5), we present an application of mesoscopic physics to acoustic and seismic waves: the principle of passive imaging. By correlating records of ambient noise or diffuse waves obtained at two passive sensors, it is possible to reconstruct the impulse response of the medium as if a source was placed at one sensor. This provides the opportunity of doing acoustics and seismology without a source. Several aspects of this technique are presented here, starting with theoretical considerations and numerical simulations (Chaps. 3, 4). Then we present experimental applications (Chap. 5) to ultrasound (passive tomography of a layered medium) and to seismic waves (passive imaging of California, and the Moon, with micro-seismic noise). Physique mésoscopique des ultrasons et des ondes sismiques : application à l'imagerie passive. Cet article de revue rassemble plusieurs aspects fondamentaux et appliqués de la propagation des ondes acoustiques et élastiques dans les milieux hétérogènes, en régime de diffusion simple ou multiple. Après une introduction sur les techniques conventionelles d'imagerie sismique et ultrasonore, nous présentons deux expériences qui mettent en évidence la présence de diffusion multiple dans les enregistrements sismologiques : l'équipartition des ondes, et la rétrodiffusion cohérente (Chap. 2). La diffusion multiple des ondes, qui démontre l'aspect mésoscopique de leur propagation, est une limitation majeure pour les techniques d'imagerie conventionelles (imagerie médicale, sismique réflexion ou réfraction, tomographie...). La deuxième partie du document (Chaps. 3 5) est consacrée à une application de cette physique mésoscopique : le principe de l'imagerie passive. En effectuant la corrélation temporelle d'enregistrement de bruit ambiant ou d'ondes diffuses, il est possible de reconstruire la réponse impulsionnelle du milieu entre deux capteurs passifs comme si l'on avait placé une source en lieu et place d'un des capteurs. Cela offre la possibilité de faire de l'acoustique ou de la sismologie sans source. Plusieurs aspects sont présentés dans ce manuscrit : des aspects théoriques et numériques (Chaps. 3, 4), ensuite des aspects expérimentaux avec des applications (Chap. 5) à l'échelle des ultrasons (tomographie passive d'un milieu stratifié), et des applications à l'échelle de la sismologie (imagerie du sous-sol de la Californie, et même de la Lune).

  3. Integrated Source of Spectrally Filtered Correlated Photons for Large-Scale Quantum Photonic Systems

    E-print Network

    Grassani, Davide

    We demonstrate the generation of quantum-correlated photon pairs combined with the spectral filtering of the pump field by more than 95 dB on a single silicon chip using electrically tunable ring resonators and passive ...

  4. correlation Mathematical

    E-print Network

    Mosegaard, Klaus

    and correlation Stimulus p(t), T images 1 ! t ! T . Signal f(t; x; y; z) measured in (x; y; z). Filter hw (t Coefficients Convolution of the stimulus: r w (t) = +1 X ø=0 p(t \\Gamma ø)hw (ø) Un­normalised signal obtained from stan­ dard correlation analysis (or equivalent t­test). Delay =) underestimates

  5. Delineating the whole brain BOLD response to passive movement kinematics.

    PubMed

    Sulzer, James; Dueñas, Julio; Stämpili, Philipp; Hepp-Reymond, Marie-Claude; Kollias, Spyros; Seifritz, Erich; Gassert, Roger

    2013-06-01

    The field of brain-machine interfaces (BMIs) has made great advances in recent years, converting thought to movement, with some of the most successful implementations measuring directly from the motor cortex. However, the ability to record from additional regions of the brain could potentially improve flexibility and robustness of use. In addition, BMIs of the future will benefit from integrating kinesthesia into the control loop. Here, we examine whether changes in passively induced forefinger movement amplitude are represented in different regions than forefinger velocity via a MR compatible robotic manipulandum. Using functional magnetic resonance imaging (fMRI), five healthy participants were exposed to combinations of forefinger movement amplitude and velocity in a factorial design followed by an epoch-based analysis. We found that primary and secondary somatosensory regions were activated, as well as cingulate motor area, putamen and cerebellum, with greater activity from changes in velocity compared to changes in amplitude. This represents the first investigation into whole brain response to parametric changes in passive movement kinematics. In addition to informing BMIs, these results have implications towards neural correlates of robotic rehabilitation. PMID:24187291

  6. Passivation of fluorinated activated charcoal

    SciTech Connect

    Del Cul, G.D.; Trowbridge, L.D.; Simmons, D.W.; Williams, D.F.; Toth, L.M.

    1997-10-01

    The Molten Salt Reactor Experiment (MSRE), at the Oak Ridge National Laboratory has been shut down since 1969 when the fuel salt was drained from the core into two Hastelloy N tanks at the reactor site. In 1995, a multiyear project was launched to remediate the potentially hazardous conditions generated by the movement of fissile material and reactive gases from the storage tanks into the piping system and an auxiliary charcoal bed (ACB). The top 12 in. of the ACB is known by gamma scan and thermal analysis to contain about 2.6 kg U-233. According to the laboratory tests, a few feet of fluorinated charcoal are believed to extend beyond the uranium front. The remainder of the ACB should consist of unreacted charcoal. Fluorinated charcoal, when subjected to rapid heating, can decompose generating gaseous products. Under confined conditions, the sudden exothermic decomposition can produce high temperatures and pressures of near-explosive characteristics. Since it will be necessary to drill and tap the ACB to allow installation of piping and instrumentation for remediation and recovery activities, it is necessary to chemically convert the reactive fluorinated charcoal into a more stable material. Ammonia can be administered to the ACB as a volatile denaturing agent that results in the conversion of the C{sub x}F to carbon and ammonium fluoride, NH{sub 4}F. The charcoal laden with NH{sub 4}F can then be heated without risking any sudden decomposition. The only consequence of heating the treated material will be the volatilization of NH{sub 4}F as a mixture of NH{sub 3} and HF, which would primarily recombine as NH{sub 4}F on surfaces below 200 C. The planned scheme for the ACB denaturing is to flow diluted ammonia gas in steps of increasing NH{sub 3} concentration, 2% to 50%, followed by the injection of pure ammonia. This report summarizes the planned passivation treatment scheme to stabilize the ACB and remove the potential hazards. It also includes basic information, results of laboratory tests, thermodynamic calculations, process description, and operational parameters, and addresses safety concerns.

  7. [The retrieval of ozone column densities by passive differential optical absorption spectroscopy during summer at Zhongshan Station, Antarctic].

    PubMed

    Luo, Yu-Han; Liu, Wen-Qing; Bian, Lin-Gen; Lu, Chang-Gui; Xie, Pin-Hua; Si, Fu-Qi; Sun, Li-Guang

    2011-02-01

    Daily ozone column densities were monitored by Passive DOAS (differential optical absorption spectroscopy) from December 10th, 2008 to Feb 19th, 2009 at Zhongshan Station, Antarctic (69 degrees 22'24" S, 76 degrees 22'14" E). Considering the absorption of O3, OClO, NO2, O4, BrO and the Ring effect, ozone slant column densities were retrieved using the zenith scattered sunlight as the light source. The results showed that there was no obvious "ozone hole" during the monitoring period, but ozone VCD (vertical column density) had greatly changed within short time scale, especially in middle December and early February. The analysis of passive DOAS and Brewer measurements of ozone VCD showed good agreement with the correlative coefficient of 0.863, while satellite board OMI measurements with the correlative coefficient of 0.840, which confirmed the validity of the monitoring of Passive DOAS. PMID:21510403

  8. Passive-solar homes for Texas

    NASA Astrophysics Data System (ADS)

    Garrison, M. L.

    1982-06-01

    Acceptance of passive solar technologies has been slow within the conventional building trades in Texas because it is a common misconception that solar is expensive, and data on local applications is severely limited or nonexistent. It is the purpose of this solar development to move passive solar design into the mainstream of public acceptance by helping to overcome and eliminate these barriers. Specifically, the goal is to develop a set of regional climatic building standards to help guide the conventional building trade toward the utilization of soft energy systems which will reduce overall consumption at a price and convenience most Texans can afford. To meet this objective, eight sample passive design structures are presented. These designs represent state of the art regional applications of passive solar space conditioning. The methodology used in the passive solar design process included: analysis of regional climatic data; analysis of historical regional building prototypes; determination of regional climatic design priorities and assets; prototypical design models for the discretionary housing market; quantitative thermal analysis of prototypical designs; and construction drawings of building prototypes.

  9. Passive MMW algorithm performance characterization using MACET

    NASA Astrophysics Data System (ADS)

    Williams, Bradford D.; Watson, John S.; Amphay, Sengvieng A.

    1997-06-01

    As passive millimeter wave sensor technology matures, algorithms which are tailored to exploit the benefits of this technology are being developed. The expedient development of such algorithms requires an understanding of not only the gross phenomenology, but also specific quirks and limitations inherent in sensors and the data gathering methodology specific to this regime. This level of understanding is approached as the technology matures and increasing amounts of data become available for analysis. The Armament Directorate of Wright Laboratory, WL/MN, has spearheaded the advancement of passive millimeter-wave technology in algorithm development tools and modeling capability as well as sensor development. A passive MMW channel is available within WL/MNs popular multi-channel modeling program Irma, and a sample passive MMW algorithm is incorporated into the Modular Algorithm Concept Evaluation Tool, an algorithm development and evaluation system. The Millimeter Wave Analysis of Passive Signatures system provides excellent data collection capability in the 35, 60, and 95 GHz MMW bands. This paper exploits these assets for the study of the PMMW signature of a High Mobility Multi- Purpose Wheeled Vehicle in the three bands mentioned, and the effect of camouflage upon this signature and autonomous target recognition algorithm performance.

  10. Passive soil vapor versus grab samples for determining volatile organic compound concentrations

    SciTech Connect

    Hewitt, A.D. [Army Cold Regions Research and Engineering Lab., Hanover, NH (United States)

    1997-12-31

    The GORE-SORBER Module, a passive soil vapor method, and the mean of two colocated grab samples handled and analyzed using an in-vial method were compared for estimating volatile organic compound (VOC) contamination in the near-surface vadose zone. The strong semi-log correlation between these two methods (r{sup 2} = 0.944) and equally strong linear correlation for grab samples taken 15 cm apart (r{sup 2} = 0.957) indicate: (1) a fairly homogeneous distribution existed for this contaminant, and (2) that this passive soil vapor technology offers a promising means of estimating subsurface concentrations in locations where grab samples cannot be easily obtained.

  11. Acceleration of passive tracers in compressible turbulent flow.

    PubMed

    Yang, Yantao; Wang, Jianchun; Shi, Yipeng; Xiao, Zuoli; He, X T; Chen, Shiyi

    2013-02-01

    In compressible turbulence at high Reynolds and Mach numbers, shocklets emerge as a new type of flow structure in addition to intense vortices as in incompressible turbulence. Using numerical simulation of compressible homogeneous isotropic turbulence, we conduct a Lagrangian study to explore the effects of shocklets on the dynamics of passive tracers. We show that shocklets cause very strong intermittency and short correlation time of tracer acceleration. The probability density function of acceleration magnitude exhibits a -2.5 power-law scaling in the high compression region. Through a heuristic model, we demonstrate that this scaling is directly related to the statistical behavior of strong negative velocity divergence, i.e., the local compression. Tracers experience intense acceleration near shocklets, and most of them are decelerated, usually with large curvatures in their trajectories. PMID:23432253

  12. Acceleration of Passive Tracers in Compressible Turbulent Flow

    NASA Astrophysics Data System (ADS)

    Yang, Yantao; Wang, Jianchun; Shi, Yipeng; Xiao, Zuoli; He, X. T.; Chen, Shiyi

    2013-02-01

    In compressible turbulence at high Reynolds and Mach numbers, shocklets emerge as a new type of flow structure in addition to intense vortices as in incompressible turbulence. Using numerical simulation of compressible homogeneous isotropic turbulence, we conduct a Lagrangian study to explore the effects of shocklets on the dynamics of passive tracers. We show that shocklets cause very strong intermittency and short correlation time of tracer acceleration. The probability density function of acceleration magnitude exhibits a -2.5 power-law scaling in the high compression region. Through a heuristic model, we demonstrate that this scaling is directly related to the statistical behavior of strong negative velocity divergence, i.e., the local compression. Tracers experience intense acceleration near shocklets, and most of them are decelerated, usually with large curvatures in their trajectories.

  13. Graphical method to analyze dynamic response of passive buildings

    SciTech Connect

    Subbarao, K.; Anderson, J.V.

    1981-07-01

    Just as the steady state behavior of a building can be understood by adding the UA values of the components, the dynamic behavior can be understood by adding vectors giving the response of the components to driving functions of any given frequency (e.g. the diurnal frequency). The vector addition can be done graphically to obtain an intuitive understanding of the role of each component. The interaction of a component with all the others can be included simply by changing the amplitude and phase of the contribution of the component. Combinations of direct gain and Trombe wall can be analyzed in this manner. Work is underway (a) to correlate the response to diurnal frequency directly to auxiliary energy as well as overheating problems and cooling season performance, and (b) to include other passive systems, movable insulation, etc.

  14. Passive immunization in experimental Herpesvirus hominis infection of newborn mice.

    PubMed Central

    Luyet, F; Samra, D; Soneji, A; Marks, M I

    1975-01-01

    Infection of newborn mice with Herpesvirus hominis type 2(HVH-2) was used as an experimental model of disseminated HVH infection in newborn humans. Mice were challenged with 103 plaque-forming units of HVH-2 intranasally and were given 0.2 ml of rabbit serum intraperitoneally. Passive immunizations with rabbit anti-HVH-2 serum resulted in a significant decrease in mortality and prolongation of survival time. This effect correlated with the neutralizing antibody titer of the serum against HVH-2 and was more pronounced when immune serum was administered 1 h after infection as compared with 24 h. These results suggest that administration of high-titer anti-HVH-2 immunoglobulins shortly after delivery could afford significant protection to the newborn of a mother with genital HVH-2 infection. PMID:173653

  15. Passive Radiator For Cooling IR Detectors In Geostationary Orbit

    NASA Astrophysics Data System (ADS)

    Grigg, R.; Havey, K.; Meyers, J.

    1985-12-01

    This paper presents an approach to the design, analysis, fabrication, and a test of a development model of 100 K passive space radiator for a geostationary meteorological satellite. Significant design considerations include the importance of heat-leak control at low temperatures and the importance of a well devised plan for elimination and control of moisture and contaminants. Fabrication issues include the ability of the design to be compatible with spacecraft assembly as well as to accommodate disassembly for repair or access to the focal plane. The results of a test of the development model are presented. The data correlation process is discussed and the need for a good means of determination of surface properties at cold temperatures is identified. A summary of recommended design and fabrication features is presented.

  16. Robust Control of Non-Passive Systems via Passification

    NASA Technical Reports Server (NTRS)

    Kelkar, A. G.; Joshi, S. M.

    1997-01-01

    This paper presents methods which enable the use of passivity-based control design techniques to control non-passive systems. For inherently non-passive finite- dimensional linear time-invaraint systems, passification methods are presented to render such systems passive by suitable compensation. The passified system can then be controlled by a class of passive linear controllers. The idea is to exploit the robust stability properties of passivity-based control laws for uncertain systems. The proposed passification methods are demonstrated by application to the ACC benchmark problem and to pitch-axis control of an F-18 High Alpha Research Vehicle (HARV) model.

  17. Passive infrared bullet detection and tracking

    SciTech Connect

    Karr, T.J.

    1994-12-31

    An apparatus and method for passively detecting a projectile such as, for example, a bullet using a passive infrared detector. A passive infrared detector is focused onto a region in which a projectile is expected to be located. Successive images of infrared radiation in the region are recorded. Background infrared radiation present in the region is suppressed such that second successive images of infrared radiation generated by the projectile as the projectile passes through the region are produced. A projectile path calculator determines the path and other aspects of the projectile by using the second successive images of infrared radiation generated by the projectile. The present invention, in certain embodiments, also determines the origin of the path of the projectile and takes a photograph of the area surrounding the origin and/or fires at least one projectile at the area surrounding the origin of the path of the projectile.

  18. Passive Cooling System for a Vehicle

    DOEpatents

    Hendricks, T. J.; Thoensen, T.

    2005-11-15

    A passive cooling system for a vehicle (114) transfers heat from an overheated internal component, for example, an instrument panel (100), to an external portion (116) of the vehicle (114), for example, a side body panel (126). The passive cooling system includes one or more heat pipes (112) having an evaporator section (118) embedded in the overheated internal component and a condenser section (120) at the external portion (116) of the vehicle (114). The evaporator (118) and condenser (120) sections are in fluid communication. The passive cooling system may also include a thermally conductive film (140) for thermally connecting the evaporator sections (118) of the heat pipes (112) to each other and to the instrument panel (100).

  19. Alternative to Nitric Acid Passivation Project Overview

    NASA Technical Reports Server (NTRS)

    Lewis, Pattie L.

    2013-01-01

    The standard practice for protection of stainless steel is a process called passivation. This procedure results in the formation of a metal oxide layer to prevent corrosion. Typical passivation procedures call for the use of nitric acid which exhibits excellent corrosion performance; however, there are a number of environmental, worker safety, and operational issues associated with its use. The longtime military specification for the passivation of stainless steel was cancelled in favor of newer specifications which allow for the use of citric acid in place of nitric acid. Citric acid offers a variety of benefits that include increased safety for personnel, reduced environmental impact, and reduced operational costs. There have been few studies, however, to determine whether citric acid is an acceptable alternative for NASA and DoD. This paper details activities to date including development of the joint test plan, on-going and planned testing, and preliminary results.

  20. Complete corrosion inhibition through graphene defect passivation.

    PubMed

    Hsieh, Ya-Ping; Hofmann, Mario; Chang, Kai-Wen; Jhu, Jian Gang; Li, Yuan-Yao; Chen, Kuang Yao; Yang, Chang Chung; Chang, Wen-Sheng; Chen, Li-Chyong

    2014-01-28

    Graphene is expected to enable superior corrosion protection due to its impermeability and chemical inertness. Previous reports, however, demonstrate limited corrosion inhibition and even corrosion enhancement of graphene on metal surfaces. To enable the reliable and complete passivation, the origin of the low inhibition efficiency of graphene was investigated. Combining electrochemical and morphological characterization techniques, nanometer-sized structural defects in chemical vapor deposition grown graphene were found to be the cause for the limited passivation effect. Extremely fast mass transport on the order of meters per second both across and parallel to graphene layers results in an inhibition efficiency of only ?50% for Cu covered with up to three graphene layers. Through selective passivation of the defects by atomic layer deposition (ALD) an enhanced corrosion protection of more than 99% was achieved, which compares favorably with commercial corrosion protection methods. PMID:24359599

  1. Passive infrared bullet detection and tracking

    DOEpatents

    Karr, Thomas J. (Alamo, CA)

    1997-01-01

    An apparatus and method for passively detecting a projectile such as, for example, a bullet using a passive infrared detector. A passive infrared detector is focused onto a region in which a projectile is expected to be located. Successive images of infrared radiation in the region are recorded. Background infrared radiation present in the region is suppressed such that second successive images of infrared radiation generated by the projectile as the projectile passes through the region are produced. A projectile path calculator determines the path and other aspects of the projectile by using the second successive images of infrared radiation generated by the projectile. The present invention, in certain embodiments, also determines the origin of the path of the projectile and takes a photograph of the area surrounding the origin and/or fires at least one projectile at the area surrounding the origin of the path of the projectile.

  2. A rapidly equilibrating, thin film, passive water sampler for organic contaminants; characterization and field testing

    Microsoft Academic Search

    Tiffany St. George; Penny Vlahos; Tom Harner; Paul Helm; Bryony Wilford

    2011-01-01

    Improving methods for assessing the spatial and temporal resolution of organic compound concentrations in marine environments is important to the sustainable management of our coastal systems. Here we evaluate the use of ethylene vinyl acetate (EVA) as a candidate polymer for thin-film passive sampling in waters of marine environments. Log KEVA?W partition coefficients correlate well (r2 = 0.87) with Log KOW values for selected

  3. Range sidelobes reduction filters for WiFi-based passive bistatic radar

    Microsoft Academic Search

    Paolo Falcone; Fabiola Colone; Pierfrancesco Lombardo; Tullio Bucciarelli

    2009-01-01

    In this paper the feasibility of a WiFi transmissions based passive bistatic radar is analysed. The auto-correlation function of this waveform of opportunity is characterized with reference to typical signals broadcasted by a 802.11 access point and it is shown to yield a high sidelobe level which strongly limits the useful dynamic range. Proper weighting networks are proposed to cope

  4. Fully Passive Wireless Acquisition of Neuropotentials

    NASA Astrophysics Data System (ADS)

    Schwerdt, Helen N.

    The ability to monitor electrophysiological signals from the sentient brain is requisite to decipher its enormously complex workings and initiate remedial solutions for the vast amount of neurologically-based disorders. Despite immense advancements in creating a variety of instruments to record signals from the brain, the translation of such neurorecording instrumentation to real clinical domains places heavy demands on their safety and reliability, both of which are not entirely portrayed by presently existing implantable recording solutions. In an attempt to lower these barriers, alternative wireless radar backscattering techniques are proposed to render the technical burdens of the implant chip to entirely passive neurorecording processes that transpire in the absence of formal integrated power sources or powering schemes along with any active circuitry. These radar-like wireless backscattering mechanisms are used to conceive of fully passive neurorecording operations of an implantable microsystem. The fully passive device potentially manifests inherent advantages over current wireless implantable and wired recording systems: negligible heat dissipation to reduce risks of brain tissue damage and minimal circuitry for long term reliability as a chronic implant. Fully passive neurorecording operations are realized via intrinsic nonlinear mixing properties of the varactor diode. These mixing and recording operations are directly activated by wirelessly interrogating the fully passive device with a microwave carrier signal. This fundamental carrier signal, acquired by the implant antenna, mixes through the varactor diode along with the internal targeted neuropotential brain signals to produce higher frequency harmonics containing the targeted neuropotential signals. These harmonics are backscattered wirelessly to the external interrogator that retrieves and recovers the original neuropotential brain signal. The passive approach removes the need for internal power sources and may alleviate heat trauma and reliability issues that limit practical implementation of existing implantable neurorecorders.

  5. A 13-WEEK COMPARISON OF PASSIVE AND CONTINUOUS OZONE MONITORS AT FORESTED SITES IN NORTH-CENTRAL PENNSYLVANIA

    EPA Science Inventory

    Ogawa passive 03 samplers were used in a 13-233k study (June 1-September 1, 1999) involving 11 forested and mountaintop sites in north-central Pennsylvania. Four of the sites were collocated with TECO model 49 O3 analyzers. A significant correlation (p...

  6. A THIRTEEN-WEEK COMPARISON OF PASSIVE AND CONTINUOUS OZONE MONITORS AT FORESTED SITES IN NORTH-CENTRAL PENNSYLVANIA

    EPA Science Inventory

    Ogawa passive 03 samplers were used in a 13-233k study (June 1-September 1, 1999) involving 11 forested and mountaintop sites in north-central Pennsylvania. Four of the sites were collocated with TECO model 49 O3 analyzers. A significant correlation (p...

  7. Passive Biomonitoring with Lichens as a Part of an Integrated Biological Measuring System for Monitoring Air Pollution in Switzerland

    Microsoft Academic Search

    R. Herzig; L. Liebendörfer; M. Urech; K. Ammann; M. Cuecheva; W. Landolt

    1989-01-01

    Passive Biomonitoring with the folious lichen Hypogymnia physodes (L.) Nyl. has been tested in Switzerland. Multielement analyses enable qualitative and quantitative conclusions about the composition and amount of important active pollutants. Many elements correlate well with the general air pollution indicator IAP18. Hypogymnia physodes possess good accumulation capacity for important air pollutants. The method has been calibrated for Pb and

  8. Correlation function studies for snow and ice

    NASA Technical Reports Server (NTRS)

    Vallese, F.; Kong, J. A.

    1981-01-01

    The random medium model is used to characterize snow and ice fields in the interpretation of active and passive microwave remote sensing data. A correlation function is used to describe the random permittivity fluctuations with the associated mean and variance and correlation lengths; and several samples are investigated to determine typical correlation functions for snow and ice. It is shown that correlation functions are extracted directly from appropriate ground truth data, and an exponential correlation function is observed for snow and ice with lengths corresponding to the actual size of ice particles or air bubbles. Thus, given that a medium has spatially stationary statistics and a small medium, the random medium model can interpret remote sensing data where theoretical parameters correspond to actual physical parameters of the terrain.

  9. Technical Assessment: WRAP 1 HVAC Passive Shutdown

    SciTech Connect

    Ball, D.E.; Nash, C.R.; Stroup, J.L.

    1993-08-12

    As the result of careful interpretation of DOE Order 6430.lA and other DOE Orders, the HVAC system for WRAP 1 has been greatly simplified. The HVAC system is now designed to safely shut down to Passive State if power fails for any reason. The fans cease functioning, allowing the Zone 1 and Zone 2 HVAC Confinement Systems to breathe with respect to atmospheric pressure changes. Simplifying the HVAC system avoided overdesign. Construction costs were reduced by eliminating unnecessary equipment. This report summarizes work that was done to define the criteria, physical concepts, and operational experiences that lead to the passive shutdown design for WRAP 1 confinement HVAC systems.

  10. An all-silicon passive optical diode.

    PubMed

    Fan, Li; Wang, Jian; Varghese, Leo T; Shen, Hao; Niu, Ben; Xuan, Yi; Weiner, Andrew M; Qi, Minghao

    2012-01-27

    A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input power is higher than the forward input. The silicon optical diode is ultracompact and is compatible with current complementary metal-oxide semiconductor processing. PMID:22194410

  11. Passive and active control of jet turbulence

    NASA Technical Reports Server (NTRS)

    Fazle Hussain, A. K. M.; Husain, H. S.

    1988-01-01

    Techniques for controlling the generation, growth, and interactions of large coherent structures in turbulent flows are discussed, reviewing the results of recent experimental investigations. The fundamental principles of active and passive coherent-structure manipulation are outlined; the effects of geometric modification are examined for the case of an elliptic jet; and particular attention is given to passive control via self-excitation, turbulence and noise suppression, control of pairing interaction via two-frequency excitation, and unsteady boundary-layer separation in wall jets. Diagrams and graphs of typical results are provided.

  12. Primordial Black Holes from Passive Density Fluctuations

    E-print Network

    Chia-Min Lin; Kin-Wang Ng

    2013-01-15

    In this paper, we show that if passive fluctuations are considered, primordial black holes (PBHs) can be easily produced in the framework of single-field, slow-roll inflation models. The formation of PBHs is due to the blue spectrum of passive fluctuations and an enhancement of the spectral range which exits horizon near the end of inflation. Therefore the PBHs are light with masses $\\lesssim 10^{15}g$ depending on the number of e-folds when the scale of our observable universe leaves horizon. These PBHs are likely to have evaporated and cannot be a candidate for dark matter but they may still affect the early universe.

  13. Heterojunction solar cell with passivated emitter surface

    DOEpatents

    Olson, Jerry M. (Lakewood, CO); Kurtz, Sarah R. (Golden, CO)

    1994-01-01

    A high-efficiency heterojunction solar cell wherein a thin emitter layer (preferably Ga.sub.0.52 In.sub.0.48 P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer.

  14. Characterization of passive elastic properties of the human medial gastrocnemius muscle belly using supersonic shear imaging.

    PubMed

    Maïsetti, Olivier; Hug, François; Bouillard, Killian; Nordez, Antoine

    2012-04-01

    The passive elastic properties of a muscle-tendon complex are usually estimated from the relationship between the joint angle and the passive resistive torque, although the properties of the different structures crossing the joint cannot be easily assessed. This study aimed to determine the passive mechanical properties of the gastrocnemius medialis muscle (GM) using supersonic shear imaging (SSI) that allows the measurement of localized muscle shear modulus (?). The SSI of the GM was taken for 7 subjects during passive ankle dorsiflexion at a range of knee positions performed on an isokinetic dynamometer. The relationship between normalized ? and the length of the gastrocnemius muscle-tendon units (GMTU) was very well fitted to an exponential model (0.944correlated with the force-length (0.964passive muscle force, and highlight its clinical applicability to evaluate the passive properties of mono- and bi-articular muscles. PMID:22326058

  15. The Apollo passive seismic experiment

    NASA Technical Reports Server (NTRS)

    Latham, G. V.; Dorman, H. J.; Horvath, P.; Ibrahim, A. K.; Koyama, J.; Nakamura, Y.

    1979-01-01

    The completed data set obtained from the 4-station Apollo seismic network includes signals from approximately 11,800 events of various types. Four data sets for use by other investigators, through the NSSDC, are in preparation. Some refinement of the lunar model based on seismic data can be expected, but its gross features remain as presented two years ago. The existence of a small, molten core remains dependent upon the analysis of signals from a single, far-side impact. Analysis of secondary arrivals from other sources may eventually resolve this issue, as well as continued refinement of the magnetic field measurements. Evidence of considerable lateral heterogeneity within the moon continues to build. The mystery of the much meteoroid flux estimate derived from lunar seismic measurements, as compared with earth-based estimates, remains; although, significant correlations between terrestrial and lunar observations are beginning to emerge.

  16. Nitric acid passivation of Ti6Al4V reduces thickness of surface oxide layer and increases trace element release.

    PubMed

    Callen, B W; Lowenberg, B F; Lugowski, S; Sodhi, R N; Davies, J E

    1995-03-01

    Passivation of Ti6Al4V and cpTi implants using methods based on the ASTM-F86 nitric acid protocol are used with the intention of reducing their surface reactivity, and consequently the corrosion potential, in the highly corrosive biologic milieu. The ASTM-F86 passivation protocol was originally developed for surgical implants made of stainless steel and chrome cobalt alloy. Using X-ray photoelectron spectroscopy (XPS) to examine the effect of nitric acid passivation on the surface oxide layer of mill-annealed Ti6Al4V and cpTi, we have found that such treatment actually reduced the oxide thickness on the alloy while having no significant effect on the pure metal. These results correlated with observations obtained using graphite furnace atomic absorption spectrophotometry (GFAAS) to detect trace element release from solid, mill-annealed, Ti6Al4V and cpTi into serum-containing culture medium. We detected significantly greater levels of Ti, Al, and V in the presence of passivated compared to nonpassivated Ti6Al4V. In contrast, nitric acid passivation did not influence Ti release from mill-annealed cpTi. These results, derived from two mill-annealed Ti-based metals, would indicate that re-examination of ASTM-F86-based passivation protocols with respect to Ti6Al4V should be considered in view of the widespread use of this alloy for biomedical devices. PMID:7615579

  17. Passive solar energy in Washington: Results of the Washington passive solar design/build/competition

    NASA Astrophysics Data System (ADS)

    1982-03-01

    The Washington Passive Solar Design and Build Competition was held in an effort to encourage the design, construction, and marketing of moderately priced passive solar homes in Washington state. Four categories were established, including single and multi-family, new design and remodel. A number of commonly made thermal mistakes are discussed. Eight winning entries are presented along with four notable entries, for each of which is given as an overview of the design, energy conservation measures, passive heating and cooling features, system operation, and thermal performance.

  18. Active and passive coping strategies in chronic pain patients 

    E-print Network

    Snow-Turek, Andrea Lynn

    1994-01-01

    This study assessed the validity of an active/passive conceptualization of coping in a sample of chronic pain patients (N = 84). The validity of active and passive coping dimensions was supported. The Coping Strategies Questionnaire...

  19. Passive Reduced Order Modeling of Multiport Interconnects via Semidefinite Programming

    E-print Network

    Mahmood, Zohaib

    In this paper we present a passive reduced order modeling algorithm for linear multiport interconnect structures. The proposed technique uses rational fitting via semidefinite programming to identify a passive transfer ...

  20. Surface passivation process of compound semiconductor material using UV photosulfidation

    DOEpatents

    Ashby, Carol I. H. (Edgewood, NM)

    1995-01-01

    A method for passivating compound semiconductor surfaces by photolytically disrupting molecular sulfur vapor with ultraviolet radiation to form reactive sulfur which then reacts with and passivates the surface of compound semiconductors.

  1. Numerical simulation of micro-fluidic passive and active mixers 

    E-print Network

    Kumar, Saurabh

    2002-01-01

    Numerical simulations of mixing using passive and active techniques are performed. For passive mixing, numerical modeling of a micro-fluidic device, build by Holden and Cremer, was performed. The micro-fluidic device consists of a Y...

  2. 21 CFR 888.3025 - Passive tendon prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Passive tendon prosthesis. (a) Identification. A passive tendon prosthesis is a device intended to be implanted made of silicon elastomer or a polyester reinforced medical grade silicone elastomer intended for use in the surgical...

  3. 21 CFR 888.3025 - Passive tendon prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Passive tendon prosthesis. (a) Identification. A passive tendon prosthesis is a device intended to be implanted made of silicon elastomer or a polyester reinforced medical grade silicone elastomer intended for use in the surgical...

  4. Prediction techniques for passive systems' probability of failure

    E-print Network

    Cavalieri d'Oro, Edoardo

    2007-01-01

    This work fits into the wider framework of the on-going debate centered on Passive System reliability. Its aim is to provide insights into the design of a dependable method to evaluate the reliability of Passive Systems. ...

  5. Passive background correction method for spatially resolved detection

    DOEpatents

    Schmitt, Randal L. (Tijeras, NM); Hargis, Jr., Philip J. (Albuquerque, NM)

    2011-05-10

    A method for passive background correction during spatially or angularly resolved detection of emission that is based on the simultaneous acquisition of both the passive background spectrum and the spectrum of the target of interest.

  6. 48 CFR 252.211-7006 - Passive Radio Frequency Identification.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...passive radio frequency identification (RFID) or item unique identification (IUID...universally identifying physical objects via RFID tags and other means. The standardized...global standards for the adoption of passive RFID technology. Exterior...

  7. Passive Tracer Dispersion with Random or Periodic Source \\Lambda

    E-print Network

    + C yy ) + source; (1) where the source (or sink) term accounts for effects of chemical reactions ([2 Introduction The dispersion of passive tracers (or passive scalars) occur in various geo­ physical

  8. Active and passive coping strategies in chronic pain patients

    E-print Network

    Snow-Turek, Andrea Lynn

    1994-01-01

    This study assessed the validity of an active/passive conceptualization of coping in a sample of chronic pain patients (N = 84). The validity of active and passive coping dimensions was supported. The Coping Strategies Questionnaire...

  9. Numerical simulation of micro-fluidic passive and active mixers

    E-print Network

    Kumar, Saurabh

    2002-01-01

    Numerical simulations of mixing using passive and active techniques are performed. For passive mixing, numerical modeling of a micro-fluidic device, build by Holden and Cremer, was performed. The micro-fluidic device consists of a Y...

  10. Synchronized passive imaging of single cavitation events

    Microsoft Academic Search

    Jean-François Aubry; Mathieu Pernot; Daurian Chauvet; Anne-Laure Boch; Mathias Fink; Mickaël Tanter

    2011-01-01

    Passive cavitation detection techniques are usually of relatively low sensitivity to single cavitation events. Moreover, a single-element transducer is generally used, so that the spatial localization of these cavitation events is not possible, or is limited to the probing volume. To both detect and localize single cavitation events over an extended volume, the following experimental set-up has been used and

  11. A passive sampler for airborne formaldehyde

    NASA Astrophysics Data System (ADS)

    Grosjean, Daniel; Williams, Edwin L.

    A simple, inexpensive passive sampler is described that is capable of reliable measurements of formaldehyde at the parts per billion (ppb) levels relevant to indoor and outdoor air quality. The passive sampler consists of a modified dual filter holder in which the upper stage serves as the diffusion barrier, the lower stage includes a 2,4-dinitrophenylhydrazine (DNPH)-coated filter which collects formaldehyde, and the space between the two stages serve as the diffusion gap. The measured sampling rate, 18.8 ± 1.8 ml min -1, was determined in experiments involving sampling of ppb levels of formaldehyde with the passive sampler and with DNPH-coated C 18 cartridges and agrees well with the value of 19.4 ± 2.0 ml min -1 calculated from theory. The measured sampling rate was independent of formaldehyde concentration (16-156 ppb) and sampling duration (1.5-72 h). The precision of the measurements for colocated passive samplers averaged 8.6% in purified and indoor air (office and museums) and 10.2% in photochemically polluted outdoor air. With a 1.2-?m pore size Teflon filter as the diffusion barrier, the detection limit is 32 ppb h, e.g. 4 ppb in an 8-h sample, 1.3 ppb in a 24-h sample, and so on. Perceived advantages and limitations of the sampler are discussed including flexibility, cost effectiveness and possible negative bias at high ambient levels of ozone.

  12. Observability requirements for passive target tracking

    Microsoft Academic Search

    Mounir Ben Ghalia; A. T. Alouani

    1993-01-01

    Observability requirements for passive target tracking in a three-dimensional coordinate system are derived. The observability problem is formulated as an optimization problem. Certain practical situations, previously known, can be identified from the established observability requirements. However, direct application of these theoretical results does not seem to be trivial for a practical situation

  13. Passive Phase Shifter for Superconducting Josephson Circuits

    Microsoft Academic Search

    D. Balashov; B. Dimov; M. Khabipov; T. Ortlepp; D. Hagedorn; A. B. Zorin; F.-I. Buchholz; F. H. Uhlmann; J. Niemeyer

    2007-01-01

    Quantized values of magnetic flux trapped in a superconducting loop enable a new type of passive phase shifting elements. These elements can be incorporated into digital Josephson circuits making their design compact. We have proven the functionality of such phase shifters fabricated in conventional Nb\\/Al trilayer technology. We report on the successful low speed operation of a rapid single flux

  14. NOTE / NOTE Transpiration-dependent passive silica

    E-print Network

    Kitajima, Kaoru

    manipulated transpiration rates by changing humidity and air movements around pot-grown plants receivingNOTE / NOTE Transpiration-dependent passive silica accumulation in cucumber (Cucumis sativus) under transport Si, through transpiration, from soils to shoots, while others actively transport silica

  15. Camp Sacajawea Passive Solar Demonstration Project

    SciTech Connect

    Not Available

    1983-08-31

    The intent of the Passive Solar Demonstration Project was to have: an actual demonstration of the effectiveness of a passive solar design and working automatic shading devices; accurate data of energy saved by the passive design and shading devices; a brochure distributed to architects, builders, and consumers, with the monitoring data and information about the project; and the continued monitoring of the building to help explain to those who are using the building the value of the system; this would not only include the 7000 members, bu visitors and other users of the facility. To accomplish these goals, a monitoring system was installed in the recently build Passive Solar Lodge at Camp Sacajawea on Casper Mountain south of Casper, Wyoming. The building was monitored continously for the remainder of the project. The installation of the automatic shading device, a curtain wall was accomplished but had some difficulty. The results indicate there is some effectiveness of the Curtain Wall, but a quantitative value would be impossible at this time.

  16. Passive Supporters of Terrorism and Phase Transitions

    E-print Network

    August, Friedrich; Delitzscher, Sascha; Hiller, Gerald; Krueger, Tyll

    2010-01-01

    We discuss some social contagion processes to describe the formation and spread of radical opinions. The dynamics of opinion spread involves local threshold processes as well as mean field effects. We calculate and observe phase transitions in the dynamical variables resulting in a rapidly increasing number of passive supporters. This strongly indicates that military solutions are inappropriate.

  17. Passive wing pitch reversal in insect flight

    Microsoft Academic Search

    ATTILA J. BERGOU; SHENG XU; Z. JANE WANG

    2007-01-01

    between hovering with flapping wings and with a continuously rotating blade (e.g. helicopter flight). Although insects have the musculature to control the wing pitch during flight, we show here that aerodynamic and wing inertia forces are sucient to pitch the wing without the aid of the muscles. We study the passive nature of wing pitching in several observed wing kinematics,

  18. Passive wing pitch reversal in insect flight

    NASA Astrophysics Data System (ADS)

    Bergou, Attila J.; Xu, Sheng; Wang, Z. Jane

    Wing pitch reversal, the rapid change of angle of attack near stroke transition, represents a difference between hovering with flapping wings and with a continuously rotating blade (e.g. helicopter flight). Although insects have the musculature to control the wing pitch during flight, we show here that aerodynamic and wing inertia forces are sufficient to pitch the wing without the aid of the muscles. We study the passive nature of wing pitching in several observed wing kinematics, including the wing motion of a tethered dragonfly, Libellula pulchella, hovering fruitfly, hovering hawkmoth and simplified dragonfly hovering kinematics. To determine whether the pitching is passive, we calculate rotational power about the torsion axis owing to aerodynamic and wing inertial forces. This is done using both direct numerical simulations and quasi-steady fluid force models. We find that, in all the cases studied here, the net rotational power is negative, signifying that the fluid force assists rather than resists the wing pitching. To further understand the generality of these results, we use the quasi-steady force model to analyse the effect of the components of the fluid forces at pitch reversal, and predict the conditions under which the wing pitch reversal is passive. These results suggest the pitching motion of the wings can be passive in insect flight.

  19. Passive Localization Methods based on Distributed Phenomena

    E-print Network

    Henderson, Thomas C.

    Passive Localization Methods based on Distributed Phenomena Felix Sawo, Thomas C. Henderson, Christopher Sikorski, and Uwe D. Hanebeck Abstract This paper is devoted to methods for localizing individual.e., rigorous exploitation of physical background knowledge) using local observations of a distributed

  20. Anchor Nodes Placement for Effective Passive Localization

    E-print Network

    Akl, Robert

    Anchor Nodes Placement for Effective Passive Localization Robert Akl, Karthik Pasupathy Department after deployment. Localization is a process used to locate sensor nodes' positional coordinates, which is vital information. The localization is generally assisted by anchor nodes that are also sensor nodes

  1. Passive Smoking in the Workplace: Selected Issues.

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. Office of Technology Assessment.

    This report provides information about the health effects of passive smoking, the types of policies that are in force in the public and private sectors to control workplace smoking, and the costs and effects of those policies. The executive summary briefly highlights the three major areas of the report: (1) a review of the studies of health…

  2. Treat mine water using passive methods

    SciTech Connect

    Kleinmann, R.L.P.; Hedin, R.S. (U.S. Bureau of Mines, Pittsburgh, PA (United States). Environmental Technology Group)

    1993-08-01

    Passive treatment represents an alternative to conventional chemical treatment of coal mine drainage. When successful, passive systems require less investment, less maintenance and usually are less expensive than conventional chemical treatment systems. As a result, during the last seven years, more than 500 passive systems have been constructed in the United States to treat coal mine drainage. Some exist as an alternative to conventional treatment; others serve as an inexpensive pretreatment step than can decrease subsequent chemical requirements. Sulfide minerals present in rock disturbed during mining can oxidize to form an acidic metal-laden solution, commonly known as acid mine drainage (AMD). Alkalinity present in the rock may partially or completely neutralize AMD, but if either acidity or excessive metal contaminants remain, the water must be treated before it can be discharged legally. The principal regulated contaminant metals of coal mine drainage are iron and manganese. Metal mine drainage often contains more toxic metals, such as cadmium, nickel, copper and zinc. Chemical treatment of AMD is estimated to cost America's mining industry more than $1 million a day. Three principal passive technologies are used in the treatment of coal mine drainage: Aerobic wetlands, wetlands constructed with an organic substrate and anoxic limestone drains (ALDS). The selection of the technology or combination of technologies to be used depends on the quality of the water being treated.

  3. Passive sonar signature estimation using bispectral techniques

    Microsoft Academic Search

    R. K. Lennartsson; J. W. C. Robinson; L. Persson; M. J. Hinich; S. McLaughlin

    2000-01-01

    An important task in underwater passive sonar signal processing is the determination of target signatures based on the narrow-band signal content in the received signal. To achieve good classification performance it is important to be able to separate the different sources (e.g. engine, hull and drive) present in the signature, and to determine the distinct frequency coupling pattern of each

  4. Passive Polarimetric Microwave Signatures Observed Over Antarctica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    WindSat satellite-based fully polarimetric passive microwave observations, expressed in the form of the Stokes vector, were analyzed over the Antarctic ice sheet. The vertically and horizontally polarized brightness temperatures (first two Stokes components) from WindSat are shown to be consistent w...

  5. USE OF PASSIVE SAMPLERS IN THE DEARS

    EPA Science Inventory

    The Detroit Exposure and Aerosol Research Study (DEARS) employs a number of passive diffusion-based samplers for the collection of select gaseous air pollutants. These pollutants include criteria gases such as ozone, carbonyls such as acrolein, and volatile organics such as 1-3, ...

  6. Time Domain Passivity Control of Haptic Interfaces

    Microsoft Academic Search

    Blake Hannaford

    2000-01-01

    A new, energy based, method is presented for controllinga haptic interface system to ensure stable contact under awide variety of operating conditions. System stability isanalyzed in terms of the time - domain definition ofpassivity. We define a "Passivity Observer" (PO) whichmeasures energy flow in and out of one or moresubsystems in real-time software. Active behavior isindicated by a negative value

  7. Complementary resistive switches for passive nanocrossbar memories

    Microsoft Academic Search

    Eike Linn; Roland Rosezin; Carsten Kügeler; Rainer Waser

    2010-01-01

    On the road towards higher memory density and computer performance, a significant improvement in energy efficiency constitutes the dominant goal in future information technology. Passive crossbar arrays of memristive elements were suggested a decade ago as non-volatile random access memories (RAM) and can also be used for reconfigurable logic circuits. As such they represent an interesting alternative to the conventional

  8. Advanced passive radiator for spaceborne cryogenic cooling

    NASA Technical Reports Server (NTRS)

    Bard, S.

    1984-01-01

    A novel design to improve the cooling capability of spaceborne cryogenic passive radiators is described. The design is based on the use of lightweight angled radiation shields, low-conductance structural supports, and a separate detachable launch-support system to reduce the parasitic heat leaks from the warm spacecraft to the cold radiator. The effectiveness of this design is demonstrated by thermal-vacuum-chamber experiments which indicate that the angled-radiation-shield assembly has an effective emittance that is an order of magnitude lower than that of the best multilayer insulation used in flight. Performance predictions based on the experiments and analytical model indicate that an advanced passive-radiator design based on this technology would be between 10 and 57 percent of the size and 10 and 36 percent of the mass of the best state-of-the-art passive radiators and would make lower temperatures (less than 60 K) and larger heat loads practical. The cooling requirements of many new spaceborne instruments could be accommodated by application of this new passive-radiator design.

  9. Passive Microwave Remote Sensing for Land Applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Land applications, in particular soil moisture retrieval, have been hampered by the lack of low frequency passive microwave observations and the coarse spatial resolution of existing sensors. The next decade could see several improved operational and exploratory missions using new technologies as w...

  10. Integrated passive and active control of structures

    NASA Astrophysics Data System (ADS)

    Neubert, Vernon H.

    1993-12-01

    A combination of passive damping and active control is needed on practical structures where sufficient modal damping is not achievable with passive damping alone. The modal theories for structural equations in state space are reviewed and some eigenvector relationship are presented which are not available elsewhere, for use later in the report. Methods for determining sensitivities of eigenvalues and eigenvectors to plant matrix and control inputs are summarized and numerical examples are presented. Procedures are developed for optimizing passive damping through use of the sensitivities of the eigenproperties, for free vibration and forced, random vibrations. Frequency-dependent behavior of viscoelastic damping material by curve-fitting is discussed, which is then used in an overdamped mini-oscillator technique for analysis of an example ten-bar truss. Two approaches are presented for designing the combination of passive viscous damping and full state feedback control. The first is iterative and makes use of eigenvalue sensitivities. The second is based on a perturbation formulation, where the desired changes in eigenvalues and eigenvectors are specified and the corresponding changes in the closed loop characteristic matrix in state space are predicted. Restrictions on the choice of eigenvalues and eigenvectors are discussed in light of related literature on eigenstructure assignment. Fortran computer programs, one coupled with the constrained function minimization program CONMIN, have been written for each type of problem.

  11. Submerged passively-safe power plant

    DOEpatents

    Herring, J.S.

    1993-09-21

    The invention as presented consists of a submerged passively-safe power station including a pressurized water reactor capable of generating at least 600 MW of electricity, encased in a double hull vessel, and provides fresh water by using the spent thermal energy in a multistage flash desalination process. 8 figures.

  12. Analytical passive mixer power gain models

    Microsoft Academic Search

    Maarten Lont; Dusan M. Milosevic; Peter G. M. Baltus; Arthur H. M. van Roermund; Guido Dolmans

    2010-01-01

    According to the well-known Friis equation the available power gain should be maximized to reduce the overall noise figure. Therefore, in receivers where an LNA is not present or its gain is low, the available power gain of the passive mixer is of interest. However, only the voltage gain is presented in many papers. In this paper an analytical model

  13. Photodetectors with passive thermal radiation control

    DOEpatents

    Lin, Shawn-Yu (Albuquerque, NM); Fleming, James G. (Albuquerque, NM); Dodson, Brian W. (Albuquerque, NM)

    2001-10-02

    A new class of photodetectors which include means for passive shielding against undesired thermal radiation is disclosed. Such devices can substitute in applications currently requiring cooled optical sensors, such as IR detection and imaging. This description is included for purposes of searching, and is not intended to limit or otherwise influence the interpretation of the present invention.

  14. Thin film magnetic materials for RFIC passives

    Microsoft Academic Search

    Y. Zhuang; M. Vroubel; B. Rejaei; J. N. Burghartz

    2005-01-01

    Recent developments of magnetic thin films for monolithic integrated radio frequency (RF) passive components are reviewed. Challenges of applying magnetic films for RF devices, i.e. ferromagnetic resonance (FMR) and eddy current effects are discussed. Nano-granular magnetic materials are foreseen to be one of the most suitable candidate materials for RFIC for the low eddy current losses and the high FMR.

  15. Thin film passive ring resonator laser gyro

    Microsoft Academic Search

    J. P. Segre; J. R. Haavisto

    1987-01-01

    This patent describes a thin film laser gyro comprising: a solid state laser; a thin film passive ring resonator; a thin film delivery loop waveguide means evanescently coupled to the resonator to deliver light from the laser into the resonator; a thin film electro-optic switch means to alternatingly inject a clockwise and a counterclockwise beam of light from the laser

  16. Soil Moisture Active Passive Validation Experiment 2008

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil Moisture Active Passive Validation Experiment 2008 (SMAPVEX08) was conducted to address specific issues identified by the SMAP satellite mission (launch 2013). SMAP is currently addressing issues related to the development and selection of retrieval algorithms as well as refining the mission de...

  17. Passive safety injection system using borated water

    SciTech Connect

    Conway, Lawrence E. (Allegheny, PA); Schulz, Terry L. (Westmoreland, PA)

    1993-01-01

    A passive safety injection system relies on differences in water density to induce natural circulatory flow patterns which help maintain prescribed concentrations of boric acid in borated water, and prevents boron from accumulating in the reactor vessel and possibly preventing heat transfer.

  18. Optimal sensor configuration for passive position estimation

    Microsoft Academic Search

    Jan Neering; Christian Fischer; Marc Bordier; N. Maizi

    2008-01-01

    The goal of passive source localization is to acoustically detect objects producing noises by multiple sensors (e.g. microphones, hydrophones) and to estimate their position using only the sound information. While within the last four decades a lot of work was carried out on how to best measure the time delay of arrivals (TDOAs) and on finding an optimal location estimator,

  19. SWINE FEVER : INFLUENCE OF PASSIVE IMMUNITY

    E-print Network

    Boyer, Edmond

    SWINE FEVER : INFLUENCE OF PASSIVE IMMUNITY ON PIG IMMUNE RESPONSE FOLLOWING VACCINATION response to swine fever virus (S.F.V.) was investigated in pigs injected with variable amounts of S (GIRAUD et al., 1974; MOWAT, 1974) or swine fever vaccine #12;within the first weeks of life (I

  20. Passive personal sampler for nitrogen dioxide

    Microsoft Academic Search

    Schnakenberg; G. H. Jr

    1976-01-01

    A passive personal sampling device for NOâ in air, developed by the New York University Medical Center, is described. The sampler has been successfully demonstrated in the field and in the laboratory. In corroborative laboratory trials the agreement with reference method is excellent. The overall accuracy is approximately +-5 percent of reading to a precision of about +-1 percent. All

  1. The Soil Moisture Active Passive (SMAP) Mission

    Microsoft Academic Search

    Dara Entekhabi; Eni G. Njoku; Peggy E. O'Neill; Kent H. Kellogg; Wade T. Crow; Wendy N. Edelstein; Jared K. Entin; Shawn D. Goodman; Thomas J. Jackson; Joel Johnson; John Kimball; Jeffrey R. Piepmeier; Randal D. Koster; Neil Martin; Kyle C. McDonald; Mahta Moghaddam; Susan Moran; Rolf Reichle; J. C. Shi; Michael W. Spencer; Samuel W. Thurman; Leung Tsang; Jakob Van Zyl

    2010-01-01

    The Soil Moisture Active Passive (SMAP) mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council's Decadal Survey. SMAP will make global measurements of the soil moisture present at the Earth's land surface and will distinguish frozen from thawed land surfaces. Direct observations of soil moisture and freeze\\/thaw state from

  2. Submerged passively-safe power plant

    DOEpatents

    Herring, J. Stephen (Idaho Falls, ID)

    1993-01-01

    The invention as presented consists of a submerged passively-safe power station including a pressurized water reactor capable of generating at least 600 MW of electricity, encased in a double hull vessel, and provides fresh water by using the spent thermal energy in a multistage flash desalination process.

  3. Passivation of InP-based HBTs

    NASA Astrophysics Data System (ADS)

    Jin, Z.; Uchida, K.; Nozaki, S.; Prost, W.; Tegude, F.-J.

    2006-08-01

    The surface effects, the (NH 4) 2S and low-temperature-deposited SiN x passivations of InP-based heterostructure bipolar transistors (HBTs) have been investigated. The surface recombination current of InP-based HBTs is related to the base structures. The (NH 4) 2S treatment for InGaAs and InP removes the natural oxide layer and results in sulfur-bonded surfaces. This can create surface-recombination-free InP-based HBTs. Degradation is found when the HBTs were exposed to air for 10 days. The low-temperature-deposited SiN x passivation of InGaAs/InP HBTs causes a drastic decrease in the base current and a significant increase in the current gain. The improvement in the HBT performance is attributed to the low deposition temperature and the effect of N 2 plasma treatment in the initial deposition process. The SiN x passivation is found to be stable. S/SiN x passivation of InGaAs/InP HBTs results in a decrease in the base current and an increase in the current gain. The annealing process can cause the base current to decrease further and the current gain increase.

  4. Multipurpose active/passive motion compensation system

    SciTech Connect

    Sullivan, R.A.; Clements, R.E.; Davenport, M.R.

    1984-05-01

    A microprocessor-controlled active/passive motion compensation system has been developed for deploying a variety of geotechnical in-situ testing devices with mobile drilling rigs from low-cost service vessels. The light-weight rotary heave compensator incorporates a hydraulic motor as the compensator actuator and a servo-controlled closed loop pump to reduce the air storage and power requirements. Unique features of the system are the use of inertial sensors to measure three components of boat motion, the ability to run the system in active/passive or passive modes, and the ability to automatically lower the drillstring at a constant velocity while maintaining motion compensation. Quantitative measurements made during sea trials offshore California yielded motion compensation accuracy approaching 98 percent which is much better than the compensation achieved with passive systems. Results are presented from offshore in-situ testing with a cone penetrometer, a vane shear device, and a suspension PS logger. The system can also be used for other offshore applications.

  5. Passively forced current sharing among transistors

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M. (Inventor)

    1991-01-01

    This application concerns a simple passive circuit that improves current balance in paralleled power MOSFETs that are not precisely matched and that are operated in their active region from a common gate drive. A nonlinear circuit consisting of diodes and resistors generates a differential gate potential required to correct for unbalance while maintaining low losses over a range of current.

  6. Passive load control for large wind turbines

    Microsoft Academic Search

    Ashwill; Thomas D

    2010-01-01

    Wind energy research activities at Sandia National Laboratories focus on developing large rotors that are lighter and more cost-effective than those designed with current technologies. Because gravity scales as the cube of the blade length, gravity loads become a constraining design factor for very large blades. Efforts to passively reduce turbulent loading has shown significant potential to reduce blade weight

  7. Mennonite Nursing Home passive solar demonstration

    SciTech Connect

    Not Available

    1984-03-01

    A long-term nursing care facility and retirement center was designed for passive solar heating. The system comprises thermal mass, thermal insulation, Trombe walls, and direct gain clerestories. Included here is a topical report, analysis of building performance, owner's perspective, designer's perspective, and summary of information dissemination activities. (MHR)

  8. CAN CONTINGENT VALUATION MEASURE PASSIVE USE VALUES

    EPA Science Inventory

    Contingent valuation (CV) is the only method currently available for practically measuring passive-use values. Because proposed laws may require that environmental regulations pass a benefit-cost test, CV has become central to the policy debate on environmental protection. Crit...

  9. The Partitioned Optical Passive Stars (POPS) topology

    Microsoft Academic Search

    Greg Gravenstreter; Rami G. Melhem; Donald M. Chiarulli; Steven P. Levitan; J. P. Teza

    1995-01-01

    This paper presents and analyzes a topological ap- proach to providing multiple data channels using cur- rent technologies. The Partitioned Optical Passive Stars (POPS) topology is an all-optical interconnec- tion architecture that uses multiple non-hierarchical couplers. POPS topologies provide powerful config- urability for optimization of system complexity, net- work throughput, power budget, and control overhead. It is shown that high

  10. Sunspot Time Series: Passive and Active Intervals

    NASA Astrophysics Data System (ADS)

    Zi?ba, S.; Nieckarz, Z.

    2014-07-01

    Solar activity slowly and irregularly decreases from the first spotless day (FSD) in the declining phase of the old sunspot cycle and systematically, but also in an irregular way, increases to the new cycle maximum after the last spotless day (LSD). The time interval between the first and the last spotless day can be called the passive interval (PI), while the time interval from the last spotless day to the first one after the new cycle maximum is the related active interval (AI). Minima of solar cycles are inside PIs, while maxima are inside AIs. In this article, we study the properties of passive and active intervals to determine the relation between them. We have found that some properties of PIs, and related AIs, differ significantly between two group of solar cycles; this has allowed us to classify Cycles 8 - 15 as passive cycles, and Cycles 17 - 23 as active ones. We conclude that the solar activity in the PI declining phase (a descending phase of the previous cycle) determines the strength of the approaching maximum in the case of active cycles, while the activity of the PI rising phase (a phase of the ongoing cycle early growth) determines the strength of passive cycles. This can have implications for solar dynamo models. Our approach indicates the important role of solar activity during the declining and the rising phases of the solar-cycle minimum.

  11. Passive compact molten salt reactor (PCMSR), modular thermal breeder reactor with totally passive safety system

    SciTech Connect

    Harto, Andang Widi [Engineering Physics Department, Faculty of Engineering, Gadjah Mada University (Indonesia)

    2012-06-06

    Design Study Passive Compact Molten Salt Reactor (PCMSR) with totally passive safety system has been performed. The term of Compact in the PCMSR name means that the reactor system is designed to have relatively small volume per unit power output by using modular and integral concept. In term of modular, the reactor system consists of three modules, i.e. reactor module, turbine module and fuel management module. The reactor module is an integral design that consists of reactor, primary and intermediate heat exchangers and passive post shutdown cooling system. The turbine module is an integral design of a multi heating, multi cooling, regenerative gas turbine. The fuel management module consists of all equipments related to fuel preparation, fuel reprocessing and radioactive handling. The preliminary calculations show that the PCMSR has negative temperature and void reactivity coefficient, passive shutdown characteristic related to fuel pump failure and possibility of using natural circulation for post shutdown cooling system.

  12. Passive compact molten salt reactor (PCMSR), modular thermal breeder reactor with totally passive safety system

    NASA Astrophysics Data System (ADS)

    Harto, Andang Widi

    2012-06-01

    Design Study Passive Compact Molten Salt Reactor (PCMSR) with totally passive safety system has been performed. The term of Compact in the PCMSR name means that the reactor system is designed to have relatively small volume per unit power output by using modular and integral concept. In term of modular, the reactor system consists of three modules, i.e. reactor module, turbine module and fuel management module. The reactor module is an integral design that consists of reactor, primary and intermediate heat exchangers and passive post shutdown cooling system. The turbine module is an integral design of a multi heating, multi cooling, regenerative gas turbine. The fuel management module consists of all equipments related to fuel preparation, fuel reprocessing and radioactive handling. The preliminary calculations show that the PCMSR has negative temperature and void reactivity coefficient, passive shutdown characteristic related to fuel pump failure and possibility of using natural circulation for post shutdown cooling system.

  13. PHACT: Parallel HOG and Correlation Tracking

    NASA Astrophysics Data System (ADS)

    Hassan, Waqas; Birch, Philip; Young, Rupert; Chatwin, Chris

    2014-03-01

    Histogram of Oriented Gradients (HOG) based methods for the detection of humans have become one of the most reliable methods of detecting pedestrians with a single passive imaging camera. However, they are not 100 percent reliable. This paper presents an improved tracker for the monitoring of pedestrians within images. The Parallel HOG and Correlation Tracking (PHACT) algorithm utilises self learning to overcome the drifting problem. A detection algorithm that utilises HOG features runs in parallel to an adaptive and stateful correlator. The combination of both acting in a cascade provides a much more robust tracker than the two components separately could produce.

  14. Double Passive Cavitation Detection of OptisonTM Shell Rupture

    E-print Network

    Illinois at Urbana-Champaign, University of

    Double Passive Cavitation Detection of OptisonTM Shell Rupture Azzdine Y. Ammi1 , Robin O). The experimental setup is based on a passive cavitation detection system described in previous work. However by ultrasonic capsule destruction [3,4]. In previous work using a passive cavitation detection (PCD) system [5

  15. Passive treatment of coal mine drainage. Information circular\\/1994

    Microsoft Academic Search

    R. S. Hedin; R. W. Narin; R. L. P. Kleinmann

    1993-01-01

    Passive methods of treating mine water use chemical and biological processes that decrease metal concentrations and neutralize acidity. Compared with conventional chemical treatment, passive methods generally require more land area, but use less costly reagents and require less operational attention and maintenance. Currenlty, three types of passive technologies exist: aerobic wetlands, organic substrate wetlands, and anoxic limestone drains. Aerobic wetlands

  16. 26 CFR 1.469-2 - Passive activity loss.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...equal to A's net rental activity...income from the building may be treated...not from a passive activity if...not from a passive activity...section, A's net rental activity...income from the building for 1997 is...equal to X's net rental activity...income from the building for 1994 is...not from a passive...

  17. MECHANICAL COMPUTATION FOR PASSIVE FORCE CONTROL Ambarish Goswami

    E-print Network

    MacIver, Malcolm A.

    a low inertia robotic wrist mounted at the end of the robot arm will have the advantage of higher mechanical bandwidth. A robotic wrist made up of passive physical components such as springs and dampers by a passive mechanical device (perhaps a wrist) has inherent advantages over active implementations. A passive

  18. Active type robotic mobility aid control based on passive behavior

    Microsoft Academic Search

    Oscar Chuy Jr; Yasuhisa Hirata; Kazuhiro Kosuge

    2007-01-01

    This paper proposes a motion control algorithm for an active type of robotic mobility aid based on passive behavior concept. Passive behavior is an important characteristic of a system that provides mobility to elderly or person with walking disability. It allows the user to control the system based on intention. Passive behavior is implemented using imposed desired dynamics, which represents

  19. Simultaneous Interconnection and Damping Assignment PassivityBased Control: Two

    E-print Network

    Batlle, Carles

    Simultaneous Interconnection and Damping Assignment Passivity­Based Control: Two Practical Examples simply adding a negative feedback loop around the passive output--an ac- tion sometimes called Lg to the passive map, and a second LgV term that in- jects damping for asymptotic stability. The purpose

  20. Advancing passive sampling of contaminants in environmental science

    E-print Network

    Mosegaard, Klaus

    . In these contributions, passive sampling approaches were applied to water, air, soil vapours, sediments and even shAdvancing passive sampling of contaminants in environmental science Philipp Mayer,a Frank Waniab and Charles S. Wongc Passive sampling has seen a tremendous rise in popularity in recent years. Improved

  1. Hybrid passivated colloidal quantum dot solids

    NASA Astrophysics Data System (ADS)

    Ip, Alexander H.; Thon, Susanna M.; Hoogland, Sjoerd; Voznyy, Oleksandr; Zhitomirsky, David; Debnath, Ratan; Levina, Larissa; Rollny, Lisa R.; Carey, Graham H.; Fischer, Armin; Kemp, Kyle W.; Kramer, Illan J.; Ning, Zhijun; Labelle, André J.; Chou, Kang Wei; Amassian, Aram; Sargent, Edward H.

    2012-09-01

    Colloidal quantum dot (CQD) films allow large-area solution processing and bandgap tuning through the quantum size effect. However, the high ratio of surface area to volume makes CQD films prone to high trap state densities if surfaces are imperfectly passivated, promoting recombination of charge carriers that is detrimental to device performance. Recent advances have replaced the long insulating ligands that enable colloidal stability following synthesis with shorter organic linkers or halide anions, leading to improved passivation and higher packing densities. Although this substitution has been performed using solid-state ligand exchange, a solution-based approach is preferable because it enables increased control over the balance of charges on the surface of the quantum dot, which is essential for eliminating midgap trap states. Furthermore, the solution-based approach leverages recent progress in metal:chalcogen chemistry in the liquid phase. Here, we quantify the density of midgap trap states in CQD solids and show that the performance of CQD-based photovoltaics is now limited by electron-hole recombination due to these states. Next, using density functional theory and optoelectronic device modelling, we show that to improve this performance it is essential to bind a suitable ligand to each potential trap site on the surface of the quantum dot. We then develop a robust hybrid passivation scheme that involves introducing halide anions during the end stages of the synthesis process, which can passivate trap sites that are inaccessible to much larger organic ligands. An organic crosslinking strategy is then used to form the film. Finally, we use our hybrid passivated CQD solid to fabricate a solar cell with a certified efficiency of 7.0%, which is a record for a CQD photovoltaic device.

  2. High-overtone bulk acoustic resonator as passive ground penetrating RADAR cooperative targets

    NASA Astrophysics Data System (ADS)

    Friedt, J.-M.; Saintenoy, A.; Chrétien, S.; Baron, T.; Lebrasseur, É.; Laroche, T.; Ballandras, S.; Griselin, M.

    2013-04-01

    RAdio-frequency Detection And Ranging instruments—RADARs—are widely used for applications aimed at measuring passive target velocity or ranging for various metrology applications such as ground position and localization. Within the context of using piezoelectric acoustic passive sensors as cooperative targets to RADARs probed through a radiofrequency link, this paper reports on investigating the compatibility of narrowband resonator architectures with the classical operation mode of wideband RADAR instruments. Since single mode resonators are hardly compatible due to the limited bandwidth of their spectrum, the investigation has been extended to High-overtone Bulk Acoustic Resonator (HBAR) whose comb of modes appears appropriate to the use with RADAR instruments. This analysis leads to consider HBARs as delay lines providing a comb of echos in the time domain rather than through the usual frequency comb considerations. Experimental measurements of HBAR responses are demonstrated using Ground Penetrating RADAR instruments fitted with a variety of antennas, and thus, operating in various frequency ranges, as well as the identification of the device temperature through the echo time delay computed as the cross correlation maximum position. Finally, the use of such cooperative targets for single reflector identification within a clutter of reflectors is theoretically considered with the proposal of a Finite-Difference Time-Domain-based simulation method encompassing both passive dielectric reflectors and the contribution of buried passive acoustic sensors.

  3. Correlative Tomography

    PubMed Central

    Burnett, T. L.; McDonald, S. A.; Gholinia, A.; Geurts, R.; Janus, M.; Slater, T.; Haigh, S. J.; Ornek, C.; Almuaili, F.; Engelberg, D. L.; Thompson, G. E.; Withers, P. J.

    2014-01-01

    Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques. PMID:24736640

  4. Correlative Tomography

    NASA Astrophysics Data System (ADS)

    Burnett, T. L.; McDonald, S. A.; Gholinia, A.; Geurts, R.; Janus, M.; Slater, T.; Haigh, S. J.; Ornek, C.; Almuaili, F.; Engelberg, D. L.; Thompson, G. E.; Withers, P. J.

    2014-04-01

    Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques.

  5. Analysis and suppression of passive noise in surface microseismic data

    NASA Astrophysics Data System (ADS)

    Forghani-Arani, Farnoush

    Surface microseismic surveys are gaining popularity in monitoring the hydraulic fracturing process. The effectiveness of these surveys, however, is strongly dependent on the signal-to-noise ratio of the acquired data. Cultural and industrial noise generated during hydraulic fracturing operations usually dominate the data, thereby decreasing the effectiveness of using these data in identifying and locating microseismic events. Hence, noise suppression is a critical step in surface microseismic monitoring. In this thesis, I focus on two important aspects in using surface-recorded microseismic seismic data: first, I take advantage of the unwanted surface noise to understand the characteristics of these noise and extract information about the propagation medium from the noise; second, I propose effective techniques to suppress the surface noise while preserving the waveforms that contain information about the source of microseisms. Automated event identification on passive seismic data using only a few receivers is challenging especially when the record lengths span over long durations of time. I introduce an automatic event identification algorithm that is designed specifically for detecting events in passive data acquired with a small number of receivers. I demonstrate that the conventional STA/LTA (Short-term Average/Long-term Average) algorithm is not sufficiently effective in event detection in the common case of low signal-to-noise ratio. With a cross-correlation based method as an extension of the STA/LTA algorithm, even low signal-to-noise events (that were not detectable with conventional STA/LTA) were revealed. Surface microseismic data contains surface-waves (generated primarily from hydraulic fracturing activities) and body-waves in the form of microseismic events. It is challenging to analyze the surface-waves on the recorded data directly because of the randomness of their source and their unknown source signatures. I use seismic interferometry to extract the surface-wave arrivals. Interferometry is a powerful tool to extract waves (including body-wave and surface-waves) that propagate from any receiver in the array (called a pseudo source) to the other receivers across the array. Since most of the noise sources in surface microseismic data lie on the surface, seismic interferometry yields pseudo source gathers dominated by surface-wave energy. The dispersive characteristics of these surface-waves are important properties that can be used to extract information necessary for suppressing these waves. I demonstrate the application of interferometry to surface passive data recorded during the hydraulic fracturing operation of a tight gas reservoir and extract the dispersion properties of surface-waves corresponding to a pseudo-shot gather. Comparison of the dispersion characteristics of the surface waves from the pseudo-shot gather with that of an active shot-gather shows interesting similarities and differences. The dispersion character (e.g. velocity change with frequency) of the fundamental mode was observed to have the same behavior for both the active and passive data. However, for the higher mode surface-waves, the dispersion properties are extracted at different frequency ranges. Conventional noise suppression techniques in passive data are mostly stacking-based that rely on enforcing the amplitude of the signal by stacking the waveforms at the receivers and are unable to preserve the waveforms at the individual receivers necessary for estimating the microseismic source location and source mechanism. Here, I introduce a technique based on the tau - p transform, that effectively identifies and separates microseismic events from surface-wave noise in the tau -p domain. This technique is superior to conventional stacking-based noise suppression techniques, because it preserves the waveforms at individual receivers. Application of this methodology to microseismic events with isotropic and double-couple source mechanism, show substantial improvement in the signal-to-noise ratio. Imaging of the processed field da

  6. Passive Diffusion of Transdermal Glucose: Noninvasive Glucose Sensing Using a Fluorescent Glucose Binding Protein.

    PubMed

    Kanjananimmanont, Sunsanee; Ge, Xudong; Mupparapu, KarunaSri; Rao, Govind; Potts, Russell; Tolosa, Leah

    2014-01-21

    The motivation for this study was to determine if a statistically significant correlation exists between blood glucose (BG) and transdermal glucose (TG) collected by passive diffusion. A positive outcome will indicate that noninvasive passive TG diffusion is a painless alternative to collecting blood through a break on the skin. Sampling involves placing a small volume of buffer solution on the surface of membrane or skin for 5 minutes. The sample is then assayed with fluorescent GBP. In vitro testing was done on regenerated cellulose and a porcine skin model to determine diffusion of standard glucose solutions. In vivo testing was done on a healthy subject and a subject with type 2 diabetes. Glucose diffused readily through the regenerated cellulose membrane with good correlation between surface and internal glucose concentrations (R (2) = .997). But the porcine skin model required a surface prewash to achieve the same good correlation R (2) = .943). Based on this, an optimum prewash step was determined for the in vivo studies. The resulting correlation coefficients between TG and BG after a 15-minute prewash in a healthy subject and type 2 subject were .87 and .93, respectively. Removal of the extraneous glucose in the skin by prewashing was an important step in achieving good correlation between TG and BG. The results suggest that passive collection of TG is a noninvasive alternative to current practice of breaking the skin. Further studies are under way to determine the lag time between TG and BG and for the sampling protocol to be more amenable to point-of-care application. PMID:24876581

  7. Correlation Migration Using Gaussian Beams of Scattered Teleseismic Body Waves

    Microsoft Academic Search

    Robert L. Nowack; Saptarshi Dasgupta; Gerard T. Schuster; Jian-Ming Sheng; Aasha Pancha; John G. Anderson; Corné Kreemer; Gabriela R. Noriega; J Ramón Arrowsmith; Lisa B. Grant; Jeri J. Young; Jianming Guo; Aiming Lin; Tadashi Maruyama; Jianjing Zheng; Guoqiang Sun; Allen L. Husker; Monica D. Kohler; Paul M. Davis; Shigeo Kinoshita; Miho Ohike; S. K. Singh; J. F. Pacheco; D. García; A. Iglesias; D. Bindi; S. Parolai; H. Grosser; C. Milkereit; S. Zünbül; S. Karakisa

    2006-01-01

    Correlation migration for structural imaging using Gaussian beams is described for the inversion of passively recorded teleseismic waves. Gaussian beam migration is based on an overcomplete frame-based representation of the seismic wave field and uses localized slant-stack windows of the data. Paraxial Gaussian beams are then utilized for the backpropagation of the seismic waves into the me- dium. The method

  8. Multiboson Correlation Interferometry with Arbitrary Single-Photon Pure States

    NASA Astrophysics Data System (ADS)

    Tamma, Vincenzo; Laibacher, Simon

    2015-06-01

    We provide a compact full description of multiboson correlation measurements of arbitrary order N in passive linear interferometers with arbitrary input single-photon pure states. This allows us to physically analyze the novel problem of multiboson correlation sampling at the output of random linear interferometers. Our results also describe general multiboson correlation landscapes for an arbitrary number of input single photons and arbitrary interferometers. In particular, we use two different schemes to demonstrate, respectively, arbitrary-order quantum beat interference and 100% visibility entanglement correlations even for input photons distinguishable in their frequencies.

  9. Evaluation of Alternate Stainless Steel Surface Passivation Methods

    SciTech Connect

    Clark, Elliot A.

    2005-05-31

    Stainless steel containers were assembled from parts passivated by four commercial vendors using three passivation methods. The performance of these containers in storing hydrogen isotope mixtures was evaluated by monitoring the composition of initially 50% H{sub 2} 50% D{sub 2} gas with time using mass spectroscopy. Commercial passivation by electropolishing appears to result in surfaces that do not catalyze hydrogen isotope exchange. This method of surface passivation shows promise for tritium service, and should be studied further and considered for use. On the other hand, nitric acid passivation and citric acid passivation may not result in surfaces that do not catalyze the isotope exchange reaction H{sub 2} + D{sub 2} {yields} 2HD. These methods should not be considered to replace the proprietary passivation processes of the two current vendors used at the Savannah River Site Tritium Facility.

  10. Dynamics of passive and active particles in the cell nucleus.

    PubMed

    Hameed, Feroz M; Rao, Madan; Shivashankar, G V

    2012-01-01

    Inspite of being embedded in a dense meshwork of nuclear chromatin, gene loci and large nuclear components are highly dynamic at 37°C. To understand this apparent unfettered movement in an overdense environment, we study the dynamics of a passive micron size bead in live cell nuclei at two different temperatures (25 and 37°C) with and without external force. In the absence of a force, the beads are caged over large time scales. On application of a threshold uniaxial force (about 10(2) pN), the passive beads appear to hop between cages; this large scale movement is absent upon ATP-depletion, inhibition of chromatin remodeling enzymes and RNAi of lamin B1 proteins. Our results suggest that the nucleus behaves like an active solid with a finite yield stress when probed at a micron scale. Spatial analysis of histone fluorescence anisotropy (a measure of local chromatin compaction, defined as the volume fraction of tightly bound chromatin) shows that the bead movement correlates with regions of low chromatin compaction. This suggests that the physical mechanism of the observed yielding is the active opening of free-volume in the nuclear solid via chromatin remodeling. Enriched transcription sites at 25°C also show caging in the absence of the applied force and directed movement beyond a yield stress, in striking contrast with the large scale movement of transcription loci at 37°C in the absence of a force. This suggests that at physiological temperatures, the loci behave as active particles which remodel the nuclear mesh and reduce the local yield stress. PMID:23077497

  11. Optimal gate-width setting for passive neutrons multiplicity counting

    SciTech Connect

    Croft, Stephen [Los Alamos National Laboratory; Evans, Louise G [Los Alamos National Laboratory; Schear, Melissa A [Los Alamos National Laboratory

    2010-01-01

    When setting up a passive neutron coincidence counter it is natural to ask what coincidence gate settings should be used to optimize the counting precision. If the gate width is too short then signal is lost and the precision is compromised because in a given period only a few coincidence events will be observed. On the other hand if the gate is too large the signal will be maximized but it will also be compromised by the high level of random pile-up or Accidental coincidence events which must be subtracted. In the case of shift register electronics connected to an assay chamber with an exponential dieaway profile operating in the regime where the Accidentals rate dominates the Reals coincidence rate but where dead-time is not a concern, simple arguments allow one to show that the relative precision on the net Reals rate is minimized when the coincidence gate is set to about 1.2 times the lie dieaway time of the system. In this work we show that making the same assumptions it is easy to show that the relative precision on the Triples rates is also at a minimum when the relative precision of the Doubles (or Reals) is at a minimum. Although the analysis is straightforward to our knowledge such a discussion has not been documented in the literature before. Actual measurement systems do not always behave in the ideal we choose to model them. Fortunately however the variation in the relative precision as a function of gate width is rather flat for traditional safeguards counters and so the performance is somewhat forgiving of the exact choice. The derivation further serves to delineate the important parameters which determine the relative counting precision of the Doubles and Triples rates under the regime considered. To illustrate the similarities and differences we consider the relative standard deviation that might be anticipated for a passive correlation count of an axial section of a spent nuclear fuel assembly under practically achievable conditions.

  12. Passive degassing during quiescence as trigger of volcanic unrest

    NASA Astrophysics Data System (ADS)

    Girona, T.; Costa Rodriguez, F.; Newhall, C. G.; Taisne, B.

    2014-12-01

    Unravelling the mechanisms that trigger the ascent of magma to the surface is crucial for making progress towards improved eruption forecasts. This is especially important for persistent degassing volcanoes, like Etna (Italy) or Mayon (Philippines), since they are the most active sub-aerial volcanoes around the world. Their activity consists of quiescent periods, dominated by abundant passive gas emissions, that alternate with unrest episodes and eruptions occurring every few months or years. In this study, we wonder how passive degassing during quiescence can affect the eruptive dynamics of persistent degassing volcanoes. We have developed a new lumped parameter model that correlates the pressure of shallow magma reservoirs with the mean degassing rates measured with monitoring systems. The model accounts for the conduit-reservoir size, the viscoelastic properties of the crust, the exsolution and expansion of bubbles at depth, the magma density changes, and the connectivity between the shallow reservoir and deeper magma sources. Our theoretical analysis demonstrates that there are many realistic scenarios under which depressurizations between 1-10 MPa occur in only a few months or years, that is, within the inter-eruptive timescale of persistent degassing volcanoes. Our results are consistent with geophysical and geodetical observations at volcanoes like Llaima (Chile), Asama (Japan), Satsuma-Iwojima (Japan), and Masaya (Nicaragua), and suggest that degassing-induced depressurization could induce magma replenishment, sudden bubble expansion at depth, collapse of the crater floor, and fractures in the reservoir wall-rock. All these processes can, in turn, lead to new unrest episodes and eruption.

  13. Passive monitoring using traffic noise recordings - case study on the Steinachtal Bridge

    NASA Astrophysics Data System (ADS)

    Salvermoser, Johannes; Stähler, Simon; Hadziioannou, Céline

    2015-04-01

    Civil structures age continuously. The early recognition of potentially critical damages is an important economical issue, but also one of public safety. Continuous tracking of small changes in the medium by using passive methods would offer an extension to established active non-destructive testing procedures at relatively low cost. Here we present a case study of structural monitoring using continuous recordings of traffic noise on a 200 meter long reinforced concrete highway bridge in Germany. Over two months of continuos geophone records are used in the frequency range of 2-8 Hz. Using passive image interferometry, evaluation of hourly cross-correlations between recordings at pairs of receivers yield velocity variations in the range of -1.5% to +2.1%. We were able to correlate our outcomes with temperature measurements of the same two month period. The measured velocity changes scale with the temperature variations with on average a dv/v of 0.064% per degree Celsius. This value is in accordance with other studies of concrete response to temperature, confirming that we are able to observe subtle changes with physical origin. It is shown that traffic noise is temporally homogenenous enough to fulfill the requirements of passive image interferometry.

  14. Phase diagram to design passive nanostructures

    E-print Network

    Lee, Jeng Yi

    2015-01-01

    A phase diagram, defined by the amplitude square and phase of scattering coefficients for absorption cross-section in each individual channel, is introduced as a universal map on the electromagnetic properties for passive scatterers. General physical bounds are naturally revealed based on the intrinsic power conservation in a passive scattering system, entailing power competitions among scattering, absorption, and extinction. Exotic scattering and absorption phenomena, from resonant scattering, invisible cloaking, coherent perfect absorber, and subwavelength superscattering can all be illustrated in this phase diagram. With electrically small core-shell scatterers as an example, we demonstrate a systematic method to design field-controllable structures based on the allowed trajectories in the phase diagram. The proposed phase diagram not only provides a simple tool to design optical devices but also promotes a deep understanding on Mie's scattering theory.

  15. Relaxing passivity for human-robot interaction.

    SciTech Connect

    Buerger, Stephen P. (Massachusetts Institute of Technology, Cambridge, MA.); Hogan, Neville

    2007-03-01

    Robots for high-force interaction with humans face particular challenges to achieve performance and coupled stability. Because available actuators are unable to provide sufficiently high force density and low impedance, controllers for such machines often attempt to mask the robots physical dynamics, though this threatens stability. Controlling for passivity, the state-of-the-art means of ensuring coupled stability, inherently limits performance to levels that are often unacceptable. A controller that imposes passivity is compared to a controller designed by a new method that uses limited knowledge of human dynamics to improve performance. Both controllers were implemented on a testbed, and coupled stability and performance were tested. Results show that the new controller can improve both stability and performance. The different structures of the controllers yield key differences in physical behavior, and guidelines are provided to assist in choosing the appropriate approach for specific applications.

  16. Passive control of wing/store flutter

    NASA Technical Reports Server (NTRS)

    Reed, W. H., III; Cazier, F. W., Jr.; Foughner, J. T., Jr.

    1980-01-01

    Results are presented for a passive flutter suppression approach known as the decoupler pylon. The decoupler pylon dynamically isolates the wing from store pitch inertia effects by means of soft spring/damper elements assisted by a low frequency feedback control system which minimizes static pitch deflections of the store because of maneuvers and changing flight conditions. Wind tunnel tests and analyses show that this relatively simple pylon suspension system provides substantial increases in flutter speed and reduces the sensitivity of flutter to changes in store inertia and center of gravity. Flutter characteristics of F-16 and YF-17 flutter models equipped with decoupler pylon mounted stores are presented and compared with results obtained on the same model configuration with active flutter suppression systems. These studies show both passive and active concepts to be effective in suppressing wing/store flutter. Also presented are data showing the influence of pylon stiffness nonlinearities on wing/store flutter.

  17. Passive Magnetic Shielding in Gradient Fields

    E-print Network

    Bidinosti, C P

    2013-01-01

    The effect of passive magnetic shielding on dc magnetic field gradients imposed by both external and internal sources is studied. It is found that for concentric cylindrical or spherical shells of high permeability material, higher order multipoles in the magnetic field are shielded progressively better, by a factor related to the order of the multipole. In regard to the design of internal coil systems for the generation of uniform internal fields, we show how one can take advantage of the coupling of the coils to the innermost magnetic shield to further optimize the uniformity of the field. These results demonstrate quantitatively a phenomenon that was previously well-known qualitatively: that the resultant magnetic field within a passively magnetically shielded region can be much more uniform than the applied magnetic field itself. Furthermore we provide formulae relevant to active magnetic compensation systems which attempt to stabilize the interior fields by sensing and cancelling the exterior fields clos...

  18. Passive appendages generate drift through symmetry breaking

    NASA Astrophysics Data System (ADS)

    L?cis, U.; Brosse, N.; Ingremeau, F.; Mazzino, A.; Lundell, F.; Kellay, H.; Bagheri, S.

    2014-10-01

    Plants and animals use plumes, barbs, tails, feathers, hairs and fins to aid locomotion. Many of these appendages are not actively controlled, instead they have to interact passively with the surrounding fluid to generate motion. Here, we use theory, experiments and numerical simulations to show that an object with a protrusion in a separated flow drifts sideways by exploiting a symmetry-breaking instability similar to the instability of an inverted pendulum. Our model explains why the straight position of an appendage in a fluid flow is unstable and how it stabilizes either to the left or right of the incoming flow direction. It is plausible that organisms with appendages in a separated flow use this newly discovered mechanism for locomotion; examples include the drift of plumed seeds without wind and the passive reorientation of motile animals.

  19. Passive appendages generate drift through symmetry breaking.

    PubMed

    L?cis, U; Brosse, N; Ingremeau, F; Mazzino, A; Lundell, F; Kellay, H; Bagheri, S

    2014-01-01

    Plants and animals use plumes, barbs, tails, feathers, hairs and fins to aid locomotion. Many of these appendages are not actively controlled, instead they have to interact passively with the surrounding fluid to generate motion. Here, we use theory, experiments and numerical simulations to show that an object with a protrusion in a separated flow drifts sideways by exploiting a symmetry-breaking instability similar to the instability of an inverted pendulum. Our model explains why the straight position of an appendage in a fluid flow is unstable and how it stabilizes either to the left or right of the incoming flow direction. It is plausible that organisms with appendages in a separated flow use this newly discovered mechanism for locomotion; examples include the drift of plumed seeds without wind and the passive reorientation of motile animals. PMID:25354545

  20. Passive appendages generate drift through symmetry breaking

    PubMed Central

    L?cis, U.; Brosse, N.; Ingremeau, F.; Mazzino, A.; Lundell, F.; Kellay, H.; Bagheri, S.

    2014-01-01

    Plants and animals use plumes, barbs, tails, feathers, hairs and fins to aid locomotion. Many of these appendages are not actively controlled, instead they have to interact passively with the surrounding fluid to generate motion. Here, we use theory, experiments and numerical simulations to show that an object with a protrusion in a separated flow drifts sideways by exploiting a symmetry-breaking instability similar to the instability of an inverted pendulum. Our model explains why the straight position of an appendage in a fluid flow is unstable and how it stabilizes either to the left or right of the incoming flow direction. It is plausible that organisms with appendages in a separated flow use this newly discovered mechanism for locomotion; examples include the drift of plumed seeds without wind and the passive reorientation of motile animals. PMID:25354545

  1. Turbulent drag reduction by passive mechanisms

    NASA Astrophysics Data System (ADS)

    Sirovich, L.; Karlsson, S.

    1997-08-01

    In many situations involving flows of high Reynolds number (where inertial forces dominate over viscous forces), such as aircraft flight and the pipeline transportation of fuels, turbulent drag is an important factor limiting performance. This has led to an extensive search for both active and passive methods for drag reduction. Here we report the results of a series of wind-tunnel experiments that demonstrate a passive means of effectively controlling turbulence in channel flow. Our approach involves the introduction of specified patterns of protrusions on the confining walls, which interact with the coherent, energy-bearing eddy structures in the wall region, and so influence the rate at which energy is dissipated in the turbulent flow. We show that relatively small changes in the arrangement of these protrusions can alter the response of the system from one of drag decrease to increased mixing (drag enhancement).

  2. Passive heat transfer means for nuclear reactors

    DOEpatents

    Burelbach, James P. (Glen Ellyn, IL)

    1984-01-01

    An improved passive cooling arrangement is disclosed for maintaining adjacent or related components of a nuclear reactor within specified temperature differences. Specifically, heat pipes are operatively interposed between the components, with the vaporizing section of the heat pipe proximate the hot component operable to cool it and the primary condensing section of the heat pipe proximate the other and cooler component operable to heat it. Each heat pipe further has a secondary condensing section that is located outwardly beyond the reactor confinement and in a secondary heat sink, such as air ambient the containment, that is cooler than the other reactor component. Means such as shrouding normally isolated the secondary condensing section from effective heat transfer with the heat sink, but a sensor responds to overheat conditions of the reactor to open the shrouding, which thereby increases the cooling capacity of the heat pipe. By having many such heat pipes, an emergency passive cooling system is defined that is operative without electrical power.

  3. Structural Damage Detection Using Virtual Passive Controllers

    NASA Technical Reports Server (NTRS)

    Lew, Jiann-Shiun; Juang, Jer-Nan

    2001-01-01

    This paper presents novel approaches for structural damage detection which uses the virtual passive controllers attached to structures, where passive controllers are energy dissipative devices and thus guarantee the closed-loop stability. The use of the identified parameters of various closed-loop systems can solve the problem that reliable identified parameters, such as natural frequencies of the open-loop system may not provide enough information for damage detection. Only a small number of sensors are required for the proposed approaches. The identified natural frequencies, which are generally much less sensitive to noise and more reliable than the identified natural frequencies, are used for damage detection. Two damage detection techniques are presented. One technique is based on the structures with direct output feedback controllers while the other technique uses the second-order dynamic feedback controllers. A least-squares technique, which is based on the sensitivity of natural frequencies to damage variables, is used for accurately identifying the damage variables.

  4. Passive load control for large wind turbines.

    SciTech Connect

    Ashwill, Thomas D.

    2010-05-01

    Wind energy research activities at Sandia National Laboratories focus on developing large rotors that are lighter and more cost-effective than those designed with current technologies. Because gravity scales as the cube of the blade length, gravity loads become a constraining design factor for very large blades. Efforts to passively reduce turbulent loading has shown significant potential to reduce blade weight and capture more energy. Research in passive load reduction for wind turbines began at Sandia in the late 1990's and has moved from analytical studies to blade applications. This paper discusses the test results of two Sandia prototype research blades that incorporate load reduction techniques. The TX-100 is a 9-m long blade that induces bend-twist coupling with the use of off-axis carbon in the skin. The STAR blade is a 27-m long blade that induces bend-twist coupling by sweeping the blade in a geometric fashion.

  5. Germanium detector passivated with hydrogenated amorphous germanium

    DOEpatents

    Hansen, William L. (Walnut Creek, CA); Haller, Eugene E. (Berkeley, CA)

    1986-01-01

    Passivation of predominantly crystalline semiconductor devices (12) is provided for by a surface coating (21) of sputtered hydrogenated amorphous semiconductor material. Passivation of a radiation detector germanium diode, for example, is realized by sputtering a coating (21) of amorphous germanium onto the etched and quenched diode surface (11) in a low pressure atmosphere of hydrogen and argon. Unlike prior germanium diode semiconductor devices (12), which must be maintained in vacuum at cryogenic temperatures to avoid deterioration, a diode processed in the described manner may be stored in air at room temperature or otherwise exposed to a variety of environmental conditions. The coating (21) compensates for pre-existing undesirable surface states as well as protecting the semiconductor device (12) against future impregnation with impurities.

  6. Photoluminescence Analysis of Electron Irradiated AlGaN/GaN HEMT structures with Variation of Silicon Nitride Passivation Thickness

    NASA Astrophysics Data System (ADS)

    Jackson, H.; Hengehold, Robert

    2014-03-01

    A passivation layer of silicon nitride on AlGaN ?GaN heterojunction devices can improve performance by reducing electron traps at the surface. In this study, the effects of passivation layer thickness was investigated at various thicknesses (0, 200, 500 and 1200 Angstroms) on AlGaN ?AlN ?GaN structures. 1.0 MeV Electron irradiations at a fluence of 1016cm-2 were used to increase the electron trapping at the interface as well as examine the impact on transport and thus ascertain the quality of the interface. Additionally, pre- and post-irradiation photoluminescence spectroscopy was used to reveal near-band-edge shallow electron donors, neutral donor bound excitons (D0XA) as well as deep center yellow/blue bands. Correlation of the post radiation spectra will be made to other device characteristics as a function of Silicon Nitride passivation thickness.

  7. Evaluation of multichannel Wiener filters applied to fine resolution passive microwave images of first-year sea ice

    NASA Technical Reports Server (NTRS)

    Full, William E.; Eppler, Duane T.

    1993-01-01

    The effectivity of multichannel Wiener filters to improve images obtained with passive microwave systems was investigated by applying Wiener filters to passive microwave images of first-year sea ice. Four major parameters which define the filter were varied: the lag or pixel offset between the original and the desired scenes, filter length, the number of lines in the filter, and the weight applied to the empirical correlation functions. The effect of each variable on the image quality was assessed by visually comparing the results. It was found that the application of multichannel Wiener theory to passive microwave images of first-year sea ice resulted in visually sharper images with enhanced textural features and less high-frequency noise. However, Wiener filters induced a slight blocky grain to the image and could produce a type of ringing along scan lines traversing sharp intensity contrasts.

  8. Approximating a Global Passive Adversary Against Tor

    Microsoft Academic Search

    Sambuddho Chakravarty; Angelos Stavrou; Angelos D. Keromytis

    We present a novel, practical, and eective mecha- nism for exposing the IP address of Tor relays, clients and hidden services. We approximate an almost-global passive adversary (GPA) capable of eavesdropping any- where in the network by using LinkWidth. LinkWidth allows network edge-attached entities to estimate the available bandwidth in an arbitrary Internet link with- out a cooperating peer host,

  9. A wireless implantable passive strain sensor system

    Microsoft Academic Search

    F. Umbrecht; M. Wendlandt; D. Juncker; C. Hierold; J. Neuenschwander

    2005-01-01

    A design study of a novel passive strain-sensor technology for the in-situ measurement of small strains on implants, bones or fixation systems is presented. The sensing principle is based on hydro-mechanical strain amplification which allows for the abandonment of any electrical circuits. Thus, the sensor can be fabricated applying solely biocompatible or bioresorbable polymeric materials. Finite element simulations are employed

  10. Novel hybrid passive componet for EDFA

    Microsoft Academic Search

    Shuihua Liu; Shan Jiang; Luozhen Fang; Guohua Yu; Qiuhua Liu

    1996-01-01

    In this paper, a novel hybrid passive component for EDFA was reported. This component integrated the 1550 nm polarization independent optical isolator and the 980\\/1550 nm pump WDM within a single compact case, and realized the reduction of insertion loss, cost and package size. The following techniques were adopted in fabricating this component: (1) high efficiency beveled end-face off-axis coupling

  11. Passive peak pressure and temperature gages

    SciTech Connect

    Staller, G.E.

    1989-03-01

    Passive pressure and temperature gages are used at the Nevada Test Site to record dynamic peak pressures and temperatures during nuclear tests. These gages offer an economical method of recording peak conditions in the superlean grout environment of an underground test. Gages are procured, assembled, and stored at the test site by Sandia for use on nuclear tests. Technical assistance is provided for installation, recovery, evaluation and documentation of these gages. 1 ref., 6 figs.

  12. Multiuser Communications Using Passive Time Reversal

    Microsoft Academic Search

    H. C. Song; W. S. Hodgkiss; W. A. Kuperman; T. Akal; M. Stevenson

    2007-01-01

    A recent paper (Song , IEEE Journal of Oceanic Engineering, vol. 31, no. 2, pp. 170-178, 2006) demonstrated multiple-input-multiple-output (MIMO) communications in shallow water using active time reversal where the time reversal array (i.e., base station) sent different messages to multiple users simultaneously over a common bandwidth channel. Passive time reversal essentially is equivalent to active time reversal with the

  13. Hydrogenation of passivated aluminum with hydrogen fluid

    Microsoft Academic Search

    H. Saitoh; A. Machida; Y. Katayama; K. Aoki

    2009-01-01

    Hydrogenation conditions of passivated aluminum were examined in a pressure and temperature range of 6-10 GPa and 300-800 °C, respectively. The relationship between the hydrogenation reaction yields and holding time was analyzed by Johnson-Mehl-Avrami equation. An Avrami exponent n of 0.3 indicated that the reaction decreased with time due to the low diffusivity of hydrogen in AlH3. The oxide layer

  14. A New Passive Sampler for Aldehydes

    Microsoft Academic Search

    Shih-wei Tsai; Shane S. Que Hee

    1999-01-01

    A new solid sorbent passive air sampler used a coated Tenax TA pellet that chemisorbed aldehydes by reaction with 10% (w\\/w) O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride. The aldehyde permeated a silicone membrane to gain access to the sampling element at the end of a cylinder of diffusion path length 1.1 cm and diameter 1.3 cm. Vapors of known concentrations around the threshold

  15. Efficient analysis of passive microstrip elements

    Microsoft Academic Search

    K. Naishadham; T. W. Nuteson

    1993-01-01

    Passive microstrip elements are analyzed by the full-wave, space domain moment method at microwave frequencies. Redundant calculations in the moment matrix are eliminated by using various symmetries manifested by the Green's functions. The Green's functions are, in general, Sommerfeld-type integrals, which are computationally intensive. Recently developed closed-form analytical approximations of the integrals are used to increase the efficiency of the

  16. Hadamard spectrometer for passive LWIR standoff surveillance

    Microsoft Academic Search

    Roman V. Kruzelecky; Brian Wong; Jing Zou; Najeeb Mohammad; Wes Jamroz; Mohammed Soltani; Mohamed Chaker; Emile Haddad; Philips Laou; Suzanne Paradis

    2007-01-01

    Based on the principle of the Integrated Optical Spectrometer (IOSPEC), a waveguide-based, longwave infrared (LWIR) dispersive spectrometer with multiple input slits for Hadamard spectroscopy was designed and built intended for passive standoff chemical agent detection in 8 to 12mum spectral range. This prototype unit equips with a three-inch input telescope providing a field-of-view of 1.2 degrees, a 16-microslit array (each

  17. Passive microring-resonator-coupled lasers

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Shakouri, Ali; Bowers, John E.

    2001-11-01

    In this letter, a passive microring-resonator-coupled semiconductor laser structure is proposed. The weakly coupled high-Q microring resonator provides a strong mode-selection filter and could considerably extend the effective cavity length of a conventional Fabry-Perot laser. The side-mode suppression ratio, the linewidth and the frequency chirp of this laser are dramatically improved comparing to distributed feedback and distributed Bragg reflector lasers.

  18. Passive modal damping with piezoelectric shunts

    SciTech Connect

    Granier, J. J. (John J.); Haundhausen, R. J. (R. Jason); Gaytan, G. E. (Gabriel E.)

    2001-01-01

    The use of piezoelectric materials in conjunction with passive inductance-resistance-capacitance (RLC) circuits to dampen specific vibration modes is explored. The piezoelectric materials convert mechanical energy to electrical energy, which is then dissipated in the RLC circuit through joule heating. An impulse is applied to a simple cantilevered beam and by varying the inductance and resistance values, the natural oscillation frequency fcir the RLC circuit is tuned to dampen the first mode of vibration.

  19. Multipurpose Active\\/Passive Motion Compensation System

    Microsoft Academic Search

    R. A. Sullivan; M. Davenport; R. Clements

    1984-01-01

    A microprocessor-controlled active\\/passive motion compensation system has been developed for deploying a variety of geotechnical in-situ testing devices with mobile drilling rigs from low-cost service vessels. The light-weight rotary heave compensator incorporates a hydraulic motor as the compensator actuator and a servo-controlled closed loop pump to reduce the air storage and power requirements. Unique features of the system are the

  20. The Acquisition of Passives in Serbian

    ERIC Educational Resources Information Center

    Perovic, Alexandra; Vuksanovic, Jasmina; Petrovic, Boban; Avramovic-Ilic, Irena

    2014-01-01

    This study examined the comprehension of actional and psychological verbs in both their active and passive (short and long) forms by 99 Serbian-speaking children. The children, whose age ranged between 3 years, 6 months (3;6) and 7 years, 6 months (7;6), were divided into three groups: 3;6-5 ("M" = 4.3), 5;1-6;1 ("M" = 5.6),…

  1. Deghosting in passive air surveillance systems

    Microsoft Academic Search

    Martina Daun

    2010-01-01

    Digital Audio\\/Video Broadcasting (DAB\\/DVB-T) is already available in a large area of Europe. The advantage of using these signals for passive air surveillance is the disposability of a large range of illuminators sending an easily decodeable digital broadcast signal. In the considered multi-static scenario, one observer provides bistatic Time Difference of Arrival (TDoA), Doppler and (with limited quality) also azimuth

  2. Accidental radio jamming suppression in passive radar

    Microsoft Academic Search

    Heng Zheng; Hongli Zhao; Fei Li

    2008-01-01

    Bistatic passive radar based on opportunity illuminators such as FM radio, is a hotspot in the domain of radar. The direct\\/multi-path signals cancellation techniques(DSC) have been discussed by many scholars. These considered algorithms adopt a single-stage adaptive filter processor frame, have sufficient performance in the cancellation of the direct\\/multi-path interference signals from the selected transmitter. In practice, because of the

  3. Tierra Nueva -- A passive solar cohousing project

    SciTech Connect

    Haggard, K.; Cooper, P.

    1999-10-01

    California architects take on the formidable challenges of designing a cohousing project, and discover that the end result is well worth the effort. The Tierra Nueva Cohousing Project consists of living units, a common house, community orchard, community gardens, community play space, space for a future shop and at the periphery of the site, parking, carports and garages. The units use thermal mass, solar heating, passive solar cooling, perimeter insulation on slabs. Design was agreed to by the community as a whole.

  4. Passive aerodynamics control of plasma instabilities

    Microsoft Academic Search

    H. G. Enjieu Kadji; B. R. Nana Nbendjo

    2012-01-01

    A smart-damping scheme is used to passively control the dynamic responses of plasma oscillations governed by a two-fluid model. For linear oscillations, the stability boundaries are determined based upon the Routh-Hurwitz criterion while the Whittaker method and Floquet theory enable to predict boundaries of unstable states. Two directions of flow speed control are considered and results of analytical predictions are

  5. Passive magnetic bearings for vehicular electromechanical batteries

    SciTech Connect

    Post, R

    1996-03-01

    This report describes the design of a passive magnetic bearing system to be used in electromechanical batteries (flywheel energy storage modules) suitable for vehicular use. One or two such EMB modules might, for example, be employed in a hybrid-electric automobile, providing efficient means for power peaking, i.e., for handling acceleration and regenerative braking power demands at high power levels. The bearing design described herein will be based on a ''dual-mode'' operating regime.

  6. Evolving uses of passive seismic arrays from continental to local scales

    NASA Astrophysics Data System (ADS)

    Schmandt, B.

    2014-12-01

    Portable passive seismic surveys are generally used to sample scales and locations that are not practical with long-term observatories, but are fundamental to studying Earth systems. The breadth of uses and designs of portable passive surveys is expanding rapidly as result of advances in instrumentation and analysis. Examples from recent passive surveys will be used illustrate how they are bringing new constraint to systems spanning continental to local scales. At continental scale EarthScope's USArray is providing a view of the transition zone between the upper and lower mantle that facilitates integration of seismology, geodynamics, and mineral physics. Recently recognized correlations between mantle flow and abrupt velocity decreases in the top of the lower mantle are consistent with laboratory constraints on the consequences of volatile cycling in the deep Earth. Arrays with similar numbers of seismometers (~103) are also being used in a passive mode on much smaller scales. The Long Beach 3D survey conducted by NodalSeismic in 2011 covered only 7x10 km in southern California with about 5,000 seismometers. The instruments were optimized for recording high frequencies (>10 Hz), but they also successfully recorded local and teleseismic earthquakes. Delay time and amplitude maps for earthquake body-waves revealed coherent structural variations at scales as small as about 400 m. Such dense sampling of teleseismic earthquake wave fields yielded new constraint on localized deep crustal deformation underlying the tectonic boundary between mainland California and the rifted Inner Continental Borderland. The utility of passive data from the Long Beach 3D survey partly motivated a recent deployment of more than 900 exploration industry seismometers to record continuously for 2 weeks at Mt. St. Helens volcano in Washington in 2014. New observations of the >50 local earthquakes recorded within the Mt. St. Helens array will also be presented.

  7. Gene-environment interactions in genetic epidemiology

    E-print Network

    Spinka, Christine Marie

    2005-02-17

    of interest for the Israeli ovarian cancer study. . . . . . . . . 37 6 Conditional probability P(G1,G2|C) of a relative pair (1,2) given their allele IBD sharing status. . . . . . . . . . . . . . . . . . . . . . . 47 7 Conditional expectation of a relative... pair (1,2) given their allele IBD sharing status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 x LIST OF FIGURES FIGURE Page 1 Pedigrees used in power calculations and comparison, which are taken from Figure 1 of Abecasis, Cookson...

  8. Gene–Environment Interactions at Nucleotide Resolution

    PubMed Central

    Gerke, Justin; Lorenz, Kim; Ramnarine, Shelina; Cohen, Barak

    2010-01-01

    Interactions among genes and the environment are a common source of phenotypic variation. To characterize the interplay between genetics and the environment at single nucleotide resolution, we quantified the genetic and environmental interactions of four quantitative trait nucleotides (QTN) that govern yeast sporulation efficiency. We first constructed a panel of strains that together carry all 32 possible combinations of the 4 QTN genotypes in 2 distinct genetic backgrounds. We then measured the sporulation efficiencies of these 32 strains across 8 controlled environments. This dataset shows that variation in sporulation efficiency is shaped largely by genetic and environmental interactions. We find clear examples of QTN:environment, QTN: background, and environment:background interactions. However, we find no QTN:QTN interactions that occur consistently across the entire dataset. Instead, interactions between QTN only occur under specific combinations of environment and genetic background. Thus, what might appear to be a QTN:QTN interaction in one background and environment becomes a more complex QTN:QTN:environment:background interaction when we consider the entire dataset as a whole. As a result, the phenotypic impact of a set of QTN alleles cannot be predicted from genotype alone. Our results instead demonstrate that the effects of QTN and their interactions are inextricably linked both to genetic background and to environmental variation. PMID:20941394

  9. Genes, Environment, and Race: Quantitative Genetic Approaches

    ERIC Educational Resources Information Center

    Whitfield, Keith E.; McClearn, Gerald

    2005-01-01

    Understanding the origins of racial health disparities is currently a central focus of health-oriented funding agencies and the health policy community. In particular, the role of genetics in the origin of racial health disparities is receiving growing attention and has been susceptible to considerable misinterpretation. In this article, the…

  10. Gene-environment interactions in hypertension

    Microsoft Academic Search

    Zdenka Pausova; Johanne Tremblay; Pavel Hamet

    1999-01-01

    Environmental factors such as stress, diet, and physical activity have long been recognized as playing an important role in\\u000a the pathogenesis of essential hypertension. Individuals may vary in their response to these factors depending on differences\\u000a in genes determining physiologic systems that mediate the response. In this article we discuss geneenvironment interactions\\u000a that contribute to the development of essential hypertension

  11. Natural fracture characterization using passive seismic illumination

    SciTech Connect

    Nihei, K.T.

    2003-01-08

    The presence of natural fractures in reservoir rock can significantly enhance gas production, especially in tight gas formations. Any general knowledge of the existence, location, orientation, spatial density, and connectivity of natural fractures, as well as general reservoir structure, that can be obtained prior to active seismic acquisition and drilling can be exploited to identify key areas for subsequent higher resolution active seismic imaging. Current practices for estimating fracture properties before the acquisition of surface seismic data are usually based on the assumed geology and tectonics of the region, and empirical or fracture mechanics-based relationships between stratigraphic curvature and fracturing. The objective of this research is to investigate the potential of multicomponent surface sensor arrays, and passive seismic sources in the form of local earthquakes to identify and characterize potential fractured gas reservoirs located near seismically active regions. To assess the feasibility of passive seismic fracture detection and characterization, we have developed numerical codes for modeling elastic wave propagation in reservoir structures containing multiple, finite-length fractures. This article describes our efforts to determine the conditions for favorable excitation of fracture converted waves, and to develop an imaging method that can be used to locate and characterize fractures using multicomponent, passive seismic data recorded on a surface array.

  12. Passive bioventing driven by natural air exchange

    SciTech Connect

    Foor, D.C.; Zwick, T.C.; Hinchee, R.E. [Battelle Columbus, OH (United States); Hoeppel, R.E. [Naval Facilities Engineering Service Center, Port Hueneme, CA (United States); Kyburg, C. [NAVFAC Engineering Command, San Diego, CA (United States); Bowling, L. [Marine Corps, Twentynine Palms, CA (United States). National Resources/Environmental Affairs Div.

    1995-12-31

    Bioventing wells installed in the vadose zone of petroleum-contaminated sites at the Marine Corps Air Ground Combat Center (MCAGCC) in Twentynine Palms, California, naturally inhale and exhale air. This natural air exchange appears to be driven primarily by barometric pressure changes. The natural air exchange was utilized to engineer a passive bioventing system in which a valve allows only air injection and prevents soil gas extraction. The system is effective in aerating petroleum-contaminated, oxygen-limited subsurface soils. This aeration resulted in enhanced biological activity and site remediation. The bioventing wells (vent wells) were fitted with a passive valve mechanism that opens when the atmospheric pressure overcomes the internal vent well pressure. When the valve is open it permits atmospheric air to enter the vent well and infiltrate into the soil, thereby stimulating bioremediation. When the vent well pressure overcomes atmospheric pressure, the valve is closed and inhibits soil gas extraction. The vent wells are installed in a coarse sand where the depth to groundwater is approximately 220 ft (67 m). Generally, deeper vent wells produce greater flowrates. Passive airflow rates of up to 7 cfm (12 m{sup 3}/h) have been achieved at the bioventing wells.

  13. Stable surface passivation process for compound semiconductors

    DOEpatents

    Ashby, Carol I. H. (Edgewood, NM)

    2001-01-01

    A passivation process for a previously sulfided, selenided or tellurated III-V compound semiconductor surface. The concentration of undesired mid-gap surface states on a compound semiconductor surface is reduced by the formation of a near-monolayer of metal-(sulfur and/or selenium and/or tellurium)-semiconductor that is effective for long term passivation of the underlying semiconductor surface. Starting with the III-V compound semiconductor surface, any oxidation present thereon is substantially removed and the surface is then treated with sulfur, selenium or tellurium to form a near-monolayer of chalcogen-semiconductor of the surface in an oxygen-free atmosphere. This chalcogenated surface is then contacted with a solution of a metal that will form a low solubility chalcogenide to form a near-monolayer of metal-chalcogen-semiconductor. The resulting passivating layer provides long term protection for the underlying surface at or above the level achieved by a freshly chalcogenated compound semiconductor surface in an oxygen free atmosphere.

  14. Renormalization group and anomalous scaling in a simple model of passive scalar advection in compressible flow

    E-print Network

    Loran Ts. Adzhemyan; Nikolaj V. Antonov

    1998-06-16

    Field theoretical renormalization group methods are applied to a simple model of a passive scalar quantity advected by the Gaussian non-solenoidal (``compressible'') velocity field with the covariance $\\propto\\delta(t-t')| x-x'|^{\\epsilon}$. Convective range anomalous scaling for the structure functions and various pair correlators is established, and the corresponding anomalous exponents are calculated to the order $\\epsilon^2$ of the $\\epsilon$ expansion. These exponents are non-universal, as a result of the degeneracy of the RG fixed point. In contrast to the case of a purely solenoidal velocity field (Obukhov--Kraichnan model), the correlation functions in the case at hand exhibit nontrivial dependence on both the IR and UV characteristic scales, and the anomalous scaling appears already at the level of the pair correlator. The powers of the scalar field without derivatives, whose critical dimensions determine the anomalous exponents, exhibit multifractal behaviour. The exact solution for the pair correlator is obtained; it is in agreement with the result obtained within the $\\epsilon$ expansion. The anomalous exponents for passively advected magnetic fields are also presented in the first order of the $\\epsilon$ expansion.

  15. Mixing of a passive scalar in isotropic and sheared homogeneous turbulence

    NASA Technical Reports Server (NTRS)

    Shirani, E.; Ferziger, J. H.; Reynolds, W. C.

    1981-01-01

    In order to calculate the velocity and scalar fields, the three dimensional, time-dependent equations of motion and the diffusion equation were solved numerically. The following cases were treated: isotropic, homogeneous turbulence with decay of a passive scalar; and homogeneous turbulent shear flow with a passive scalar whose mean varies linearly in the spanwise direction. The solutions were obtained at relatively low Reynolds numbers so that all of the turbulent scales could be resolved without modeling. Turbulent statistics such as integral length scales, Taylor microscales, Kolmogorov length scale, one- and two-point correlations of velocity-velocity and velocity-scalar, turbulent Prandtl/Schmidt number, r.m.s. values of velocities, the scalar quantity and pressure, skewness, decay rates, and decay exponents were calculated. The results are compared with the available expermental results, and good agreement is obtained.

  16. Ocean bottom profiling with ambient noise: a model for the passive fathometer.

    PubMed

    Traer, James; Gerstoft, Peter; Hodgkiss, William S

    2011-04-01

    A model is presented for the complete passive fathometer response to ocean surface noise, interfering discrete noise sources, and locally uncorrelated noise in an ideal waveguide. The leading order term of the ocean surface noise contribution produces the cross-correlation of vertical multipaths and yields the depth of sub-bottom reflectors. Discrete noise incident on the array via multipaths give multiple peaks in the fathometer response. These peaks may obscure the sub-bottom reflections but can be attenuated with use of minimum variance distortionless response (MVDR) steering vectors. The seabed critical angle introduces discontinuities in the spatial distribution of distant surface noise and may introduce spurious peaks in the passive fathometer response. These peaks can be attenuated by beamforming within a bandwidth limited by the array geometry and critical angle. PMID:21476639

  17. The Relationship of Tropical Cyclone Convective Intensity to Passive Microwave Observations

    NASA Technical Reports Server (NTRS)

    Hood, Robbie E.; Guillory, Anthony; LaFontaine, Frank J.; Cecil, Dan; Heymsfield, Gerald; Arnold, James E. (Technical Monitor)

    2002-01-01

    During the 1998 and 2001 hurricane seasons, the Advanced Microwave Precipitation Radiometer (AMPR) was flown aboard the National Aeronautics and Space Administration (NASA) ER-2 high altitude aircraft as part of the Third Convection And Moisture EXperiment (CAMEX-3) and the Fourth Convection And Moisture Experiment (CAMEX-4). Several hurricanes and tropical storms were sampled during these experiments. The passive microwave observations of these tropical cyclones collected at frequencies of 10.7, 19.35, 37.1, and 85.5 GHz will be presented to explain differences in precipitation features of the hurricanes. In particular, the relationship of the passive microwave signatures of precipitation-sized ice to vertical updraft strength will be examined as a possible indicator of future convective intensity. Correlated aircraft radar, lightning, visible and infrared information will also be examined to provide further insight.

  18. Application of passive sampling for measuring dissolved concentrations of organic contaminants in the water column at three marine superfund sites.

    PubMed

    Burgess, Robert M; Lohmann, Rainer; Schubauer-Berigan, Joseph P; Reitsma, Pamela; Perron, Monique M; Lefkovitz, Lisa; Cantwell, Mark G

    2015-08-01

    Currently, there is an effort under way to encourage remedial project managers at contaminated sites to use passive sampling to collect freely dissolved concentrations (Cfree ) of hydrophobic organic contaminants to improve site assessments. The objective of the present study was to evaluate the use of passive sampling for measuring water column Cfree for several hydrophobic organic contaminants at 3 US Environmental Protection Agency Superfund sites. Sites investigated included New Bedford Harbor (New Bedford, MA, USA), Palos Verdes Shelf (Los Angeles, CA, USA), and Naval Station Newport (Newport, RI, USA); and the passive samplers evaluated were polyethylene, polydimethylsiloxane-coated solid-phase microextraction fibers, semipermeable membrane devices, and polyoxymethylene. In general, the different passive samplers demonstrated good agreement, with Cfree values varying by a factor of 2 to 3. Further, at New Bedford Harbor, where conventional water sample concentrations were also measured (i.e., grab samples), passive sampler-based Cfree values agreed within a factor of 2. These findings suggest that all of the samplers were experiencing and measuring similar Cfree during their respective deployments. Also, at New Bedford Harbor, a strong log-linear, correlative, and predictive relationship was found between polyethylene passive sampler accumulation and lipid-normalized blue mussel bioaccumulation of polychlorinated biphenyls (r(2) ?=?0.92, p?passive sampling for generating scientifically accurate water column Cfree values, which is critical for making informed environmental management decisions at contaminated sediment sites. Environ Toxicol Chem 2015;34:1720-1733. Published 2015 SETAC. This article is a US Government work and is in the public domain in the USA. PMID:26039657

  19. Passive NMIS Measurements to Estimate the Shape of Plutonium Assemblies

    SciTech Connect

    Mattingly, J.K.; Chiang, L.G.; March-Leuba, J.A.; Mihalczo, J.T.; Mullens, J.A.; Perez, R.B.; Valentine, T.E.

    1999-07-22

    A new technique to estimate the shape attribute of plutonium assemblies using the Nuclear Materials Identification System (NMIS) is described. The proposed method possesses a number of advantages. It is passive no external radiation source is required to estimate the shape of plutonium assemblies. Instead, inherent gamma and neutron emissions from spontaneous fission of {sup 240}Pu and subsequent induced fission of {sup 239}Pu are detected to estimate the shape attribute. The technique is also stationary: shape is estimated without scanning the assembly by moving the detectors relative to the assembly. The proposed method measures third order correlations between triplets of gamma/neutron-sensitive detectors. The real coincidence of a pair of gammas is used as a ''trigger'' to approximately identify the time of a spontaneous or induced fission event. The spatial location of this fission event is inferred from the real coincidence of a subsequent neutron with the initial pair of correlated gammas by using the neutron's time-of-flight (approximately the delay between the gamma pair and the neutron) and the fission neutron spectra of {sup 240}Pu and {sup 239}Pu. The spatial distribution of fission sites and hence the approximate shape of the plutonium assembly is thereby inferred by measuring the distribution of a large number of these correlated triplets. Proof-of-principle measurements were performed using {sup 252}Cf as a surrogate for {sup 240}Pu to demonstrate that the technique is feasible. For the simple shapes approximated with {sup 252}Cf sources, the measurements showed that the proposed method is capable of correctly identifying the shape and accurately estimating its size to within a few percent of actual.

  20. Consequences of passive smoking in home environment.

    PubMed

    Ka?ucka, Sylwia

    2007-01-01

    Passive smoking means cigarette smoke inhaling by people other than smokers. Passive smoker inhales tobacco smoke coming not only from side-stream, but also smoke exhaled by the smoker. Long-term tobacco smoke inhaling increases the risk of appearance of smoke related diseases (for example COPD, heart diseases), including the most dangerous types of cancer, which only few smokers realize. The aim of this study was to check whether tobacco smoke inhaling in home environment from childhood to adulthood has an influence on respiratory system of adults. The study included adults. In the study two types of participants division were used. Among 1481 persons two groups were separated. Group 1 contains people, who have never lived in home environment with active smokers, altogether 465 persons. Group 2 contains people who from birth have been exposed to cigarette smoke inhaling (altogether 1016 persons). With help of the author's questionnaire the information concerning demographic features and smoking habit were gathered. The patients underwent doctor's examination. They had a spirometric test and a chest radiogram. Statistically significant differences appear among persons with higher education who belong to two different groups. The number of children who have lived in smoke free rooms during childhood and adolescence and finished studies is bigger than the number of active smokers' children (p<0.001). Over 90% of never smokers have inhaled cigarette smoke since childhood in home environment. Chronic obstructive pulmonary disease has been diagnosed at 47.5% of active smokers, 48.3% of ex-smokers and up to 44.7% of passive smokers. Cigarette smoking and smoke inhaling for more than twenty years has a significant influence on the appearance of COPD. No statistically significant differences were noted among the three groups of participants. (p>0.05). Cigarette smoke inhaling at childhood and adolescence should be taken seriously because it causes development of chronic diseases like COPD. GOLD 2006 standards convince that at every stage of COPD development the effects of this disease may be partly reversed if one stops smoking cigarettes. That is why a child should not be exposed to cigarette smoke at any stage of its life. Permanent inhalation of tobacco smoke since early childhood in home environment influences equal occurrence of COPD at passive, ex- and active smokers. Reduction of tobacco consumption, better care concerning passive smokers, increasing consciousness of parents smoking in home environment may protect their children from serious health consequences in the future. PMID:18409274

  1. Tracking marine mammals using passive acoustics

    NASA Astrophysics Data System (ADS)

    Nosal, Eva-Marie

    2007-12-01

    It is difficult to study the behavior and physiology of marine mammals or to understand and mitigate human impact on them because much of their lives are spent underwater. Since sound propagates for long distances in the ocean and since many cetaceans are vocal, passive acoustics is a valuable tool for studying and monitoring their behavior. After a brief introduction to and review of passive acoustic tracking methods, this dissertation develops and applies two new methods. Both methods use widely-spaced (tens of kilometers) bottom-mounted hydrophone arrays, as well as propagation models that account for depth-dependent sound speed profiles. The first passive acoustic tracking method relies on arrival times of direct and surface-reflected paths. It is used to track a sperm whale using 5 at the Atlantic Undersea Test and Evaluation Center (AUTEC) and gives position estimates that are accurate to within 10 meters. With such accuracy, the whale's pitch and yaw are estimated by assuming that its main axis (which points from the tail to the rostrum) is parallel to its velocity. Roll is found by fitting the details of the pulses within each sperm whale click to the so-called bent horn model of sperm whale sound production. Finally, given the position and orientation of the whale, its beam pattern is reconstructed and found to be highly directional with an intense forward directed component. Pair-wise spectrogram (PWS) processing is the second passive acoustic tracking method developed in this dissertation. Although it is computationally more intensive, PWS has several advantages over arrival-time tracking methods, especially in shallow water environments, for long duration calls, and for multiple-animal datasets, as is the case for humpback whales on Hawaiian breeding grounds. Results of simulations with realistic noise conditions and environmental mismatch are given and compared to other passive localization techniques. When applied to the AUTEC sperm whale dataset, PWS position estimates are within meters of those obtained using the time-of-arrival method.

  2. Design and build of the Brillant Pebbles Passive IR sensor

    Microsoft Academic Search

    John Hoschette; Bob Murphy; Art Leary; Walt Watson; Tim White

    1993-01-01

    This paper describes the design, construction, and preflight certification testing of the Brilliant Pebbles Passive IR sensor. The passive IR sensor is comprised of a 64 x 64 HgCdTe hybrid focal plane array, cassegrain telescope, switchable filter and compensating electronics. The switchable filter allows the passive IR sensor to image in the Midwave or Long-wave IR bands. The sensor performance

  3. Passive cooling for initiation of therapeutic hypothermia in neonatal encephalopathy

    Microsoft Academic Search

    Giles S Kendall; Andrew Kapetanakis; Nandiran Ratnavel; Denis Azzopardi; Nicola J Robertson

    2010-01-01

    ObjectiveTo determine the feasibility of passive cooling to initiate therapeutic hypothermia before and during transport.MethodsConsensus guidelines were developed for passive cooling at the referring hospital and on transport by the London Neonatal Transfer Service. These were evaluated in a prospective study.ResultsBetween January and October 2009, 39 infants were referred for therapeutic hypothermia; passive cooling was initiated at the referring hospital

  4. Passive Lossless Snubbers For High Frequency PWM Converters

    Microsoft Academic Search

    Sam Ben-yaakov; Gregory Ivensky

    Introduction1. Seminar objectives2. Hard versus soft switching3. Diode reverse recovery4. IGBT behavior under hard switching5. Why soft switching?6. Soft switching terminology7. Soft switching by passive lossless snubbers8. Simulation toolsChapter 2. Passive lossless snubbers perspective1. Passive lossless snubber approaches2. Snubbers evolution3. The switched inductor (SIM) model4, Basic switching cell of common PWM converters5. Fundamental principles6. Practical...

  5. Cooperative passive-solar commercial retrofit

    NASA Astrophysics Data System (ADS)

    Brown, W. T.

    1982-12-01

    The primary objectives of this project were: the conversion of an existing south-facing storefront into a trombe'-wall passive solar collector, the sharing of information on simple low-cost energy alternatives with the local community, and the reduction of the store building's dependence on non-renewable fossil fuel for space heating. Six 6' wide pre-assembled collector glazing panels were mounted on a 12' high by 36' long portion of the south-facing masonry wall. Vent-holes were cut through the wall at each panel to provide air inlets and outlets for the collector and monitoring equipment was installed to record performance. A series of hands-on construction workshops were attended by Co-op and community members. During these sessions, collector components were assembled. The panels were installed on April 22, 1981 in celebration of Earth Day. Additional sessions were held to complete the project, make necessary modifications and install sensors. Project personnel participated in several energy-education activities, including workshops, seminars and alternative energy home tours. A community-based energy resource council was founded with the assistance of several key Co-op project members and a fully-illustrated How-To manual, entitled Passive Solar Collector: A Trombe'-Wall Retrofit Guide was published. Finally, a variety of energy conservation measures were undertaken. These included a new airlock store entry, insulated store ceiling, destratification ceiling fans and wood-burning furnaces have combined with the passive solar collector to substantially reduce the use of fuel oil for heat.

  6. Passive mode locking in the near infrared

    SciTech Connect

    Sibbett, W.; Taylor, J.R.

    1984-02-01

    Passive mode locking in the previously uncovered 705-798 nm spectral region has been achieved with a simple flashlamp-pumped dye laser using rhodamine 700 as the active medium with DCI (1, 1'-Diethyl-4, 4'-carbocyanine iodide) and DDCI (1, 1' Diethyl-2, 2'-dicarbocyanine iodide) as saturable absorbers. Pulses having duration in the range 4-7 ps with peak powers up to 10 MW have been produced. Several other saturable absorbers have also been shown to operate successfully in this wavelength range. 10 references.

  7. Passive injection control for microfluidic systems

    DOEpatents

    Paul, Phillip H.; Arnold, Don W.; Neyer, David W.

    2004-12-21

    Apparatus for eliminating siphoning, "dead" regions, and fluid concentration gradients in microscale analytical devices. In its most basic embodiment, the present invention affords passive injection control for both electric field-driven and pressure-driven systems by providing additional fluid flow channels or auxiliary channels disposed on either side of a sample separation column. The auxiliary channels are sized such that volumetric fluid flow rate through these channels, while sufficient to move the sample away from the sample injection region in a timely fashion, is less than that through the sample separation channel or chromatograph.

  8. Apparatus for passive removal of subsurface contaminants

    DOEpatents

    Pemberton, B.E.; May, C.P.; Rossabi, J.

    1997-06-24

    An apparatus is provided which passively removes contaminated gases from a subsurface. The apparatus includes a riser pipe extending into a subsurface which has an exterior end in fluid communication with a valve. When well pressure is greater than atmospheric pressure, the valve opens to release contaminants into the atmosphere, and when well pressure is less than atmospheric pressure, the valve closes to prevent flow of air into the well. The valve assembly of the invention comprises a lightweight ball which is lifted from its valve seat with a slight pressure drop between the well and the atmosphere. 7 figs.

  9. Apparatus for passive removal of subsurface contaminants

    DOEpatents

    Pemberton, Bradley E. (Aiken, SC); May, Christopher P. (Fairfax, VA); Rossabi, Joseph (Aiken, SC)

    1997-01-01

    An apparatus is provided which passively removes contaminated gases from a subsurface. The apparatus includes a riser pipe extending into a subsurface which has an exterior end in fluid communication with a valve. When well pressure is greater than atmospheric pressure, the valve opens to release contaminants into the atmosphere, and when well pressure is less than atmospheric pressure, the valve closes to prevent flow of air into the well. The valve assembly of the invention comprises a lightweight ball which is lifted from its valve seat with a slight pressure drop between the well and the atmosphere.

  10. Passive primary mirror concept for SOFIA

    NASA Astrophysics Data System (ADS)

    Jones, Peter A.; House, David F.; Genberg, Victor L.

    1995-06-01

    The Stratospheric Observatory for Infrared Astronomy is a planned 2.5 meter telescope that will be installed in a modified Boeing 747 aircraft and operated at altitudes above 40,000 feet. The telescope requires a primary mirror with an areal density of less than 70 kg/m(superscript 2) which can operate at elevations from 15 degrees to 70 degrees, and reach thermal equilibrium at -40 degrees C in less than 2 hours. A passive lightweighted monolithic primary mirror design with no active figure control has been shown to be a key element in meeting these requirements. A comparison of mirror designs using alternate mirror materials will be described.

  11. Passivation of InP-based HBTs

    Microsoft Academic Search

    Z. Jin; K. Uchida; S. Nozaki; W. Prost; F.-J. Tegude

    2006-01-01

    The surface effects, the (NH4)2S and low-temperature-deposited SiNx passivations of InP-based heterostructure bipolar transistors (HBTs) have been investigated. The surface recombination current of InP-based HBTs is related to the base structures. The (NH4)2S treatment for InGaAs and InP removes the natural oxide layer and results in sulfur-bonded surfaces. This can create surface-recombination-free InP-based HBTs. Degradation is found when the HBTs

  12. Estimating animal population density using passive acoustics

    PubMed Central

    Marques, Tiago A; Thomas, Len; Martin, Stephen W; Mellinger, David K; Ward, Jessica A; Moretti, David J; Harris, Danielle; Tyack, Peter L

    2013-01-01

    Reliable estimation of the size or density of wild animal populations is very important for effective wildlife management, conservation and ecology. Currently, the most widely used methods for obtaining such estimates involve either sighting animals from transect lines or some form of capture-recapture on marked or uniquely identifiable individuals. However, many species are difficult to sight, and cannot be easily marked or recaptured. Some of these species produce readily identifiable sounds, providing an opportunity to use passive acoustic data to estimate animal density. In addition, even for species for which other visually based methods are feasible, passive acoustic methods offer the potential for greater detection ranges in some environments (e.g. underwater or in dense forest), and hence potentially better precision. Automated data collection means that surveys can take place at times and in places where it would be too expensive or dangerous to send human observers. Here, we present an overview of animal density estimation using passive acoustic data, a relatively new and fast-developing field. We review the types of data and methodological approaches currently available to researchers and we provide a framework for acoustics-based density estimation, illustrated with examples from real-world case studies. We mention moving sensor platforms (e.g. towed acoustics), but then focus on methods involving sensors at fixed locations, particularly hydrophones to survey marine mammals, as acoustic-based density estimation research to date has been concentrated in this area. Primary among these are methods based on distance sampling and spatially explicit capture-recapture. The methods are also applicable to other aquatic and terrestrial sound-producing taxa. We conclude that, despite being in its infancy, density estimation based on passive acoustic data likely will become an important method for surveying a number of diverse taxa, such as sea mammals, fish, birds, amphibians, and insects, especially in situations where inferences are required over long periods of time. There is considerable work ahead, with several potentially fruitful research areas, including the development of (i) hardware and software for data acquisition, (ii) efficient, calibrated, automated detection and classification systems, and (iii) statistical approaches optimized for this application. Further, survey design will need to be developed, and research is needed on the acoustic behaviour of target species. Fundamental research on vocalization rates and group sizes, and the relation between these and other factors such as season or behaviour state, is critical. Evaluation of the methods under known density scenarios will be important for empirically validating the approaches presented here. PMID:23190144

  13. Passive containment cooling water distribution device

    DOEpatents

    Conway, Lawrence E. (Hookstown, PA); Fanto, Susan V. (Plum Borough, PA)

    1994-01-01

    A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using a series of radial guide elements and cascading weir boxes to collect and then distribute the cooling water into a series of distribution areas through a plurality of cascading weirs. The cooling water is then uniformly distributed over the curved surface by a plurality of weir notches in the face plate of the weir box.

  14. Single laser beam based passive optical sorter

    NASA Astrophysics Data System (ADS)

    Brzobohatý, O.; Karasek, V.; Å iler, M.; Chvatal, L.; Cizmar, T.; Zemanek, P.

    2013-03-01

    We demonstrate experimentally a new method of sorting of colloidal particle suspension in wide single laser beam. The sorting is performed in a realization of a "tractor" beam a weakly focused laser beam that is retro-reflected under an oblique angle. In this configuration the lateral positions of particles dependent on the direction of linear polarization of the beam. Polarization rotation by 90 degrees changes the sign of the lateral optical force acting upon particles of certain properties and such particles are propelled in the opposite direction. This approach provides surprisingly efficient way of passive sorting of tens of particles by pure switching the beam polarization.

  15. Estimating animal population density using passive acoustics.

    PubMed

    Marques, Tiago A; Thomas, Len; Martin, Stephen W; Mellinger, David K; Ward, Jessica A; Moretti, David J; Harris, Danielle; Tyack, Peter L

    2013-05-01

    Reliable estimation of the size or density of wild animal populations is very important for effective wildlife management, conservation and ecology. Currently, the most widely used methods for obtaining such estimates involve either sighting animals from transect lines or some form of capture-recapture on marked or uniquely identifiable individuals. However, many species are difficult to sight, and cannot be easily marked or recaptured. Some of these species produce readily identifiable sounds, providing an opportunity to use passive acoustic data to estimate animal density. In addition, even for species for which other visually based methods are feasible, passive acoustic methods offer the potential for greater detection ranges in some environments (e.g. underwater or in dense forest), and hence potentially better precision. Automated data collection means that surveys can take place at times and in places where it would be too expensive or dangerous to send human observers. Here, we present an overview of animal density estimation using passive acoustic data, a relatively new and fast-developing field. We review the types of data and methodological approaches currently available to researchers and we provide a framework for acoustics-based density estimation, illustrated with examples from real-world case studies. We mention moving sensor platforms (e.g. towed acoustics), but then focus on methods involving sensors at fixed locations, particularly hydrophones to survey marine mammals, as acoustic-based density estimation research to date has been concentrated in this area. Primary among these are methods based on distance sampling and spatially explicit capture-recapture. The methods are also applicable to other aquatic and terrestrial sound-producing taxa. We conclude that, despite being in its infancy, density estimation based on passive acoustic data likely will become an important method for surveying a number of diverse taxa, such as sea mammals, fish, birds, amphibians, and insects, especially in situations where inferences are required over long periods of time. There is considerable work ahead, with several potentially fruitful research areas, including the development of (i) hardware and software for data acquisition, (ii) efficient, calibrated, automated detection and classification systems, and (iii) statistical approaches optimized for this application. Further, survey design will need to be developed, and research is needed on the acoustic behaviour of target species. Fundamental research on vocalization rates and group sizes, and the relation between these and other factors such as season or behaviour state, is critical. Evaluation of the methods under known density scenarios will be important for empirically validating the approaches presented here. PMID:23190144

  16. Passivation-free solid state battery

    DOEpatents

    Abraham, K.M.; Peramunage, D.

    1998-06-16

    This invention pertains to passivation-free solid-state rechargeable batteries composed of Li{sub 4}Ti{sub 5}O{sub 12} anode, a solid polymer electrolyte and a high voltage cathode. The solid polymer electrolyte comprises a polymer host, such as polyacrylonitrile, poly(vinyl chloride), poly(vinyl sulfone), and poly(vinylidene fluoride), plasticized by a solution of a Li salt in an organic solvent. The high voltage cathode includes LiMn{sub 2}O{sub 4}, LiCoO{sub 2}, LiNiO{sub 2} and LiV{sub 2}O{sub 5} and their derivatives. 5 figs.

  17. Passivation-free solid state battery

    DOEpatents

    Abraham, Kuzhikalail M. (Needham, MA); Peramunage, Dharmasena (Norwood, MA)

    1998-01-01

    This invention pertains to passivation-free solid-state rechargeable batteries composed of Li.sub.4 Ti.sub.5 O.sub.12 anode, a solid polymer electrolyte and a high voltage cathode. The solid polymer electrolyte comprises a polymer host, such as polyacrylonitrile, poly(vinyl chloride), poly(vinyl sulfone), and poly(vinylidene fluoride), plasticized by a solution of a Li salt in an organic solvent. The high voltage cathode includes LiMn.sub.2 O.sub.4, LiCoO.sub.2, LiNiO.sub.2 and LiV.sub.2 O.sub.5 and their derivatives.

  18. Ionic transport in passivation layered on the lithium electrode

    NASA Astrophysics Data System (ADS)

    Nimon, Eugeny S.; Churikov, Alexei V.; Shirokov, Alexander V.; Lvov, Arlen L.; Chuvashkin, Anatoly N.

    1993-04-01

    The processes of ionic transport in passivating layers on the surface of the lithium electrode in solutions based on thionyl chloride, propylene carbonate and gamma -butyrolactone have been studied by means of pulse electrochemical methods. The data obtained are quantitatively described by a model which takes into account transport of both the intrinsic mobile lithium ions of the passivating layer and lithium ions injected into the passivating layer from the electrode or from the electrolyte solution under anodic or cathodic current directions, respectively. The values of mobility and concentration of mobile lithium ions in passivating layers formed on lithium in various solutions under open-circuit conditions have been determined.

  19. Passive Superconducting Shielding: Experimental Results and Computer Models

    NASA Technical Reports Server (NTRS)

    Warner, Brent; Kamiya, Koki

    2003-01-01

    Passive superconducting shielding for magnetic refrigerators has advantages over active shielding and passive ferromagnetic shielding in that it is lightweight and easy to construct. However, it is not as easy to model and does not fail gracefully. Failure of a passive superconducting shield may lead to persistent flwc and persistent currents. Unfortunately, modeling software for superconducting materials is not as easily available as is software for simple coils or for ferromagnetic materials. This paper will discuss ways of using available software to model passive superconducting shielding.

  20. Statistics of passive tracers in three-dimensional magnetohydrodynamic turbulence

    E-print Network

    Schmidt, Matthias

    Statistics of passive tracers in three-dimensional magnetohydrodynamic turbulence Angela Busse; accepted 7 November 2007; published online 13 December 2007 Magnetohydrodynamic MHD turbulence is studied

  1. Passive Superconducting Shielding: Experimental Results and Computer Models

    NASA Technical Reports Server (NTRS)

    Warner, B. A.; Kamiya, K.

    2003-01-01

    Passive superconducting shielding for magnetic refrigerators has advantages over active shielding and passive ferromagnetic shielding in that it is lightweight and easy to construct. However, it is not as easy to model and does not fail gracefully. Failure of a passive superconducting shield may lead to persistent flux and persistent currents. Unfortunately, modeling software for superconducting materials is not as easily available as is software for simple coils or for ferromagnetic materials. This paper will discuss ways of using available software to model passive superconducting shielding.

  2. An investigation of a passively controlled haptic interface

    SciTech Connect

    Davis, J.T. [Oak Ridge National Lab., TN (United States); Book, W.J. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Mechanical Engineering

    1997-03-01

    Haptic interfaces enhance cooperation between humans and robotic manipulators by providing force and tactile feedback to the human user during the execution of arbitrary tasks. The use of active actuators in haptic displays presents a certain amount of risk since they are capable of providing unacceptable levels of energy to the systems upon which they operate. An alternative to providing numerous safeguards is to remove the sources of risk altogether. This research investigates the feasibility of trajectory control using passive devices, that is, devices that cannot add energy to the system. Passive actuators are capable only of removing energy from the system or transferring energy within the system. It is proposed that the utility of passive devices is greatly enhanced by the use of redundant actuators. In a passive system, once motion is provided to the system, presumably by a human user, passive devices may be able to modify this motion to achieve a desired resultant trajectory. A mechanically passive, 2-Degree-of-Freedom (D.O.F.) manipulator has been designed and built. It is equipped with four passive actuators: two electromagnetic brakes and two electromagnetic clutches. This paper gives a review of the literature on passive and robotics and describes the experimental test bed used in this research. Several control algorithms are investigated, resulting in the formulation of a passive control law.

  3. Limit Cycles in a Passive Compass Gait Biped and Passivity-Mimicking Control Laws

    Microsoft Academic Search

    Ambarish Goswami; Bernard Espiau; Ahmed Keramane

    1997-01-01

    It is well-known that a suitably designed unpowered mechanical biped robotcan "walk" down an inclined plane with a steady periodic gait. The energyrequired to maintain the motion comes from the conversion of the biped's gravitationalpotential energy as it descends. Investigation of such passive naturalmotions may potentially lead us to strategies useful for controlling active walkingmachines as well as to understand

  4. Failure probability evaluation of passive system using fuzzy Monte Carlo simulation

    Microsoft Academic Search

    M. Hari Prasad; Avinash J. Gaikwad; A. Srividya; A. K. Verma

    2011-01-01

    Passive systems have become an inherent feature of the advanced reactors. The main reason being the passive systems are, theoretically, more reliable than the active ones. Nevertheless the passive system may fail to fulfill its mission not only because of a consequence of classical mechanical failure of component (passive or active) of the passive system, but also due to the

  5. Multitarget, multisensor localization and tracking using passive antennas and optical sensors on UAVs

    NASA Astrophysics Data System (ADS)

    Schikora, Marek; Bender, Daniel; Koch, Wolfgang; Cremers, Daniel

    2010-10-01

    In this work we focus on the task to localize and track multiple non-cooperative targets by a passive antenna array and an optical sensor. Both sensor systems are mounted on a UAV and obtain bearing measurements from the targets, where the number of targets is unknown. To solve the localization and tracking problem, the imprecise but unique bearing data collected from the antenna array has to be correlated with the precise but ambiguous bearing data gained from the optical system. We perform this by a Monte Carlo realization of a multi-sensor probability hypothesis density (PHD) filter.

  6. Diffusion and geometric effects in passive advection by random arrays of vortices

    NASA Astrophysics Data System (ADS)

    Avellaneda, M.; Torquato, S.; Kim, I. C.

    1991-08-01

    The dispersion in complex chaotic flows is investigated analytically by studying Lagrangian transport of passive scalar in incompressible, random stationary velocity fields. Monte Carlo simulations of the Langevin equations and analysis are employed to examine the effects of vortex density, vortex strength, and sign of vorticity on the Lagrangian history of a fluid particle. A theory is proposed to account for the difference in the Lagrangian autocorrelation and the mean-square displacement when the density of the vorticity increases and long-range correlations in the sign of the vorticity are present.

  7. Passive and active middle ear implants

    PubMed Central

    Beutner, Dirk; Hüttenbrink, Karl-Bernd

    2011-01-01

    Besides eradication of chronic middle ear disease, the reconstruction of the sound conduction apparatus is a major goal of modern ear microsurgery. The material of choice in cases of partial ossicular replacement prosthesis is the autogenous ossicle. In the event of more extensive destruction of the ossicular chain diverse alloplastic materials, e.g. metals, ceramics, plastics or composits are used for total reconstruction. Their specialised role in conducting sound energy within a half-open implant bed sets high demands on the biocompatibility as well as the acoustic-mechanic properties of the prosthesis. Recently, sophisticated titanium middle ear implants allowing individual adaptation to anatomical variations are widely used for this procedure. However, despite modern developments, hearing restoration with passive implants often faces its limitations due to tubal-middle-ear dysfunction. Here, implantable hearing aids, successfully used in cases of sensorineural hearing loss, offer a promising alternative. This article reviews the actual state of affairs of passive and active middle ear implants. PMID:22073102

  8. Passive millimeter-wave imaging polarimeter system

    NASA Astrophysics Data System (ADS)

    Persons, Christopher M.; Martin, Christopher A.; Jones, Michael W.; Kolinko, Vladimir; Lovberg, John A.

    2009-05-01

    The Army has identified a need to rapidly identify, map, and classify natural and manmade features to aid situational awareness as well as mission and tactical planning. To address these needs, Digital Fusion and Trex Enterprises have designed a full Stokes, passive MMW imaging polarimeter that is capable of being deployed on an unmanned aerial vehicle. Results of a detailed trade study are presented, where an architecture, waveband and target platform are selected. The selected architecture is a pushbroom phased-array system, which allows the system to collect a wide fieldof- view image with minimal components and weight. W band is chosen as a trade-off between spatial resolution, weather penetration, and component availability. The trade study considers several unmanned aerial system (UAS) platforms that are capable of low-level flight and that can support the MMW antenna. The utility of the passive Stokes imager is demonstrated through W band phenomenology data collections at horizontal and vertical polarization using a variety of natural and manmade materials. The concept design is detailed, along with hardware and procedures for both radiometric and polarimetric calibration. Finally, a scaled version of the concept design is presented, which is being fabricated for an upcoming demonstration on a small, manned aircraft.

  9. Passive versus active mitigation cost analysis

    SciTech Connect

    Parazin, R.J.; Galbraith, J.D.

    1995-04-01

    The scope of this task is to assess the impact of mitigation alternatives for Tanks 241-SY-101 and 241-SY-103 on the Project W-236A Multi-Function Waste Tank Facility. This assessment and other related tasks are part of an Action Plan Path Forward prepared by the Tank Waste Remediation System (TWRS) Life Extension and Transition Program. Task 3.7 of the Action Plan for Project W-236A MWTF analyzed the comparative cost/risk of two hydrogen gas mitigation alternatives (active versus passive) to recommend the most appropriate course of action to resolve the hydrogen gas safety issue. The qualitative success of active mitigation has been demonstrated through Tank 241-SY-101 testing. Passive mitigation has not been demonstrated but will be validated by laboratory test work performed under Task 3.1 of the Action Plan. It is assumed for this assessment that the uncertainties associated with the performance of either alternative is comparable. Determining alternative specific performance measures beyond those noted are not in the scope of this effort.

  10. Passive Broad-Spectrum Influenza Immunoprophylaxis

    PubMed Central

    Berry, Cassandra M.; Penhale, William J.; Sangster, Mark Y.

    2014-01-01

    Influenza is a perennial problem affecting millions of people annually with the everpresent threat of devastating pandemics. Active prophylaxis by vaccination against influenza virus is currently the main countermeasure supplemented with antivirals. However, disadvantages of this strategy include the impact of antigenic drift, necessitating constant updating of vaccine strain composition, and emerging antiviral drug resistance. The development of other options for influenza prophylaxis, particularly with broad acting agents able to provide protection in the period between the onset of a pandemic and the development of a strain specific vaccine, is of great interest. Exploitation of broad-spectrum mediators could provide barricade protection in the early critical phase of influenza virus outbreaks. Passive immunity has the potential to provide immediate antiviral effects, inhibiting virus replication, reducing virus shedding, and thereby protecting vulnerable populations in the event of an impending influenza pandemic. Here, we review passive broad-spectrum influenza prophylaxis options with a focus on harnessing natural host defenses, including interferons and antibodies. PMID:25328697

  11. Silicone wristbands as personal passive samplers.

    PubMed

    O'Connell, Steven G; Kincl, Laurel D; Anderson, Kim A

    2014-03-18

    Active-sampling approaches are commonly used for personal monitoring, but are limited by energy usage and data that may not represent an individual's exposure or bioavailable concentrations. Current passive techniques often involve extensive preparation, or are developed for only a small number of targeted compounds. In this work, we present a novel application for measuring bioavailable exposure with silicone wristbands as personal passive samplers. Laboratory methodology affecting precleaning, infusion, and extraction were developed from commercially available silicone, and chromatographic background interference was reduced after solvent cleanup with good extraction efficiency (>96%). After finalizing laboratory methods, 49 compounds were sequestered during an ambient deployment which encompassed a diverse set of compounds including polycyclic aromatic hydrocarbons (PAHs), consumer products, personal care products, pesticides, phthalates, and other industrial compounds ranging in log K(ow) from -0.07 (caffeine) to 9.49 (tris(2-ethylhexyl) phosphate). In two hot asphalt occupational settings, silicone personal samplers sequestered 25 PAHs during 8- and 40-h exposures, as well as 2 oxygenated-PAHs (benzofluorenone and fluorenone) suggesting temporal sensitivity over a single work day or week (p < 0.05, power =0.85). Additionally, the amount of PAH sequestered differed between worksites (p < 0.05, power = 0.99), suggesting spatial sensitivity using this novel application. PMID:24548134

  12. Optical passive athermalization for infrared zoom system

    NASA Astrophysics Data System (ADS)

    Li, Shenghui; Yang, Changcheng; Zheng, Jia; Lan, Ning; Xiong, Tao; Li, Yong

    2007-12-01

    In an infrared zoom system, it is difficult to obtain the best thermal compensation for all effective focal length (EFL) simultaneously by moving a single lens group. According to the principle of optical passive athermalization, the equations of focal length, achromatization and athermalization of both long and short EFL are established respectively. By analyzing the thermal aberration value relations between long EFL and short EFL, the thermal aberration values of the switching groups for short EFL athermalization are calculated. Firstly, the athermalization of long EFL is designed. Then through reasonable optical materials matching of the switching groups, the short EFL achieves athermalization as well. In this paper, a re-imaging switching zoom system is designed. It has a relative aperture of f/4.0, 100% cold shield efficiency, the EFL of 180mm/30mm at 3.7-4.8?m. The long EFL includes four refractive elements and one hybrid refractive/diffractive element. The switching groups of short EFL have two types, one is composed of four refractive elements, and the other is composed of two refractive elements and one hybrid refractive/diffractive element. Both of the short EFL achieve athermalization. With the aluminum materials of system structures, the zoom system achieves optical passive athermalization. It has the diffraction limited image quality and stable image plane from -30°C to 70°C.

  13. Passive solar energy information user study

    SciTech Connect

    Belew, W.W.; Wood, B.L.; Marle, T.L.; Reinhardt, C.L.

    1980-11-01

    The results of a series of telephone interviews with groups of users of information on passive solar heating and cooling are described. These results, part of a larger study on many different solar technologies, identify types of information each group needed and the best ways to get information to each group. The overall study provides baseline data about information needs in the solar community. An earlier study identified the information user groups in the solar community and the priority (to accelerate solar energy commercialization) of getting information to each group. In the current study only high-priority groups were examined. Results from seven passive groups respondents are analyzed in this report: Federally Funded Researchers, Manufacturer Representatives, Architects, Builders, Educators, Cooperative Extension Service County Agents, and Homeowners. The data will be used as input to the determination of information products and services the Solar Energy Research Institute, the Solar Energy Information Data Bank Network, and the entire information outreach community should be preparing and disseminating.

  14. Linear and passive silicon optical isolator

    PubMed Central

    Wang, Chen; Zhong, Xiao-Lan; Li, Zhi-Yuan

    2012-01-01

    On-chip optical isolation plays a key role in optical communications and computing based on silicon integrated photonic structures and has attracted great attentions for long years. Recently there have appeared hot controversies upon whether isolation of light can be realized via linear and passive photonic structures. Here we demonstrate optical isolation of infrared light in purely linear and passive silicon photonic structures. Both numerical simulations and experimental measurements show that the round-trip transmissivity of in-plane infrared light across a silicon photonic crystal slab heterojunction diode could be two orders of magnitudes smaller than the forward transmissivity at around 1,550?nm with a bandwidth of about 50?nm, indicating good performance of optical isolation. The occurrence of in-plane light isolation is attributed to the information dissipation due to off-plane and side-way scattering and selective modal conversion in the multiple-channel structure and has no conflict with the reciprocal principle. PMID:22993699

  15. Application of damage detection methods using passive reconstruction of impulse response functions.

    PubMed

    Tippmann, J D; Zhu, X; Lanza di Scalea, F

    2015-02-28

    In structural health monitoring (SHM), using only the existing noise has long been an attractive goal. The advances in understanding cross-correlations in ambient noise in the past decade, as well as new understanding in damage indication and other advanced signal processing methods, have continued to drive new research into passive SHM systems. Because passive systems take advantage of the existing noise mechanisms in a structure, offshore wind turbines are a particularly attractive application due to the noise created from the various aerodynamic and wave loading conditions. Two damage detection methods using a passively reconstructed impulse response function, or Green's function, are presented. Damage detection is first studied using the reciprocity of the impulse response functions, where damage introduces new nonlinearities that break down the similarity in the causal and anticausal wave components. Damage detection and localization are then studied using a matched-field processing technique that aims to spatially locate sources that identify a change in the structure. Results from experiments conducted on an aluminium plate and wind turbine blade with simulated damage are also presented. PMID:25583863

  16. The influence of niobium and vanadium on passivity of titanium-based implants in physiological solution.

    PubMed

    Metikos-Hukovi?, M; Kwokal, A; Piljac, J

    2003-09-01

    Surface films play a key role in corrosion and osteointegration processes of titanium-based orthopedic implants. The influence of niobium and vanadium as alloying elements on titanium alloy passivity have been investigated in Hanks' Balanced Salt Solution (HBSS), at 37 degrees C and pH 6.9.Ti6Al4V and Ti6Al6Nb have been considered. The excellent passivating properties of the anodically formed Ti(IV)-based surface oxide film and high corrosion resistance of the Ti6Al6Nb alloy have been attributed to the stabilizing effect of Nb(5+) cations on the passive film, by annihilation of stoichiometric defects (anion vacancies) caused by the presence of titanium suboxides. Localized corrosion sensitivity of the Ti6Al4V alloy has been correlated to the dissolution of vanadium at the surface film/electrolyte interface coupled with generation of cation vacancies and their diffusion through the film as a part of the solid-state diffusion process. The presence of a high concentration of chloride ions (0.15gl(-1)) in HBSS further accelerates these processes. PMID:12818549

  17. Monitoring of urban particulate using an electret-based passive sampler

    SciTech Connect

    Thorpe, A.; Hemingway, M.A.; Brown, R.C.

    1999-11-01

    Site sampling trials have been carried out in the urban environment in order to assess the usefulness of a passive sampling device, originally developed for personal monitoring of airborne dust levels in industry. The sampling element is a small disc of elect material (polymer carrying a permanent electric charge) within a metal frame weighing approximately 15 g. The sampler is designed to capture particles by electrostatic attraction, in which case the capture rate depends on their electrical mobility but is independent of the rate at which air flows past the device. Passive samplers, along with miniaturized cascade impactors, have been exposed to urban particulate for periods of up to 28 days in locations with significant different levels of airborne pollution. The cascade impactor data enabled good estimates to be made of PM{sub 10} and PMN{sub 2.5} levels, and data from the passive sampler correlated with the total dust sampled by the impactor and with both the size fractions, that with the PM{sub 10} being better. Too few data have yet been obtained for its accuracy to be established, but it is unlikely that it will approach that of pumped samplers. It has been shown to be potentially useful for multiple, simultaneous site sampling and for monitoring personal environmental exposure situations in which dispensing with a power source is particularly useful. Being small, the sampler is easy to hide or camouflage, and because it is cheap, its loss or damage is not a serious matter.

  18. Feasibility study of detection of hazardous airborne pollutants using passive open-path FTIR

    NASA Astrophysics Data System (ADS)

    Segal-Rosenheimer, M.; Dubowski, Y.; Jahn, C.; Schäfer, K.; Gerl, G.; Linker, R.

    2010-04-01

    In recent years open-path FTIR systems (active and passive) have demonstrated great potential and success for monitoring air pollution, industrial stack emissions, and trace gas constituents in the atmosphere. However, most of the studies were focused mainly on monitoring gaseous species and very few studies have investigated the feasibility of detecting bio-aerosols and dust by passive open-path FTIR measurements. The goal of the present study was to test the feasibility of detecting a cloud of toxic aerosols by a passive mode open-path FTIR. More specifically, we are focusing on the detection of toxic organophosphorous nerve agents for which we use Tri-2-ethyl-hexyl-phosphate as a model compound. We have determined the compounds' optical properties, which were needed for the radiative calculations, using a procedure developed in our laboratory. In addition, measurements of the aerosol size distribution in an airborne cloud were performed, which provided the additional input required for the radiative transfer model. This allowed simulation of the radiance signal that would be measured by the FTIR instrument and hence estimation of the detection limit of such a cloud. Preliminary outdoor measurements have demonstrated the possibility of detecting such a cloud using two detection methods. However, even in a simple case consisting of the detection of a pure airborne cloud, detection is not straightforward and reliable identification of the compound would require more advanced methods than simple correlation with spectral library.

  19. Molecular simulations of structures and solvation free energies of passivated gold nanoparticles in supercritical CO2

    NASA Astrophysics Data System (ADS)

    Yang, Zhen; Yang, Xiaoning; Xu, Zhijun; Yang, Nannan

    2010-09-01

    The interfacial structures and solvation free energies of gold nanoparticles passivated by self-assembled monolayer (SAM) of fluorinated alkanethiols in supercritical CO2 (scCO2) have been studied by using classical molecular dynamics simulation. A fragment-based free-energy perturbation approach was developed here, in which the solvation free energy of passivated metal nanoparticles was partitioned into the contributions from the inner metal core and the outer SAM. This is a first-time attempt to directly simulate the solvation free energy of nano-objects in supercritical fluids. The simulation result suggests that the nanoparticles can be thermodynamically soluble at lower scCO2 density but insoluble at higher density. We have demonstrated that this density dependence of solvation free energy can be ascribed to the effect of the surface SAM in scCO2. The presence of solvent molecules greatly affects the morphology of SAM on nanoparticle. It was observed that increasing the chain length in SAM makes nanoparticles more solvophilic at lower scCO2 density or more solvophobic at higher density. This solvation thermodynamics behavior has been correlated with the specific solvation structure of scCO2 around the passivated nanoparticles.

  20. Imparting passivity to vapor deposited magnesium alloys

    NASA Astrophysics Data System (ADS)

    Wolfe, Ryan C.

    Magnesium has the lowest density of all structural metals. Utilization of low density materials is advantageous from a design standpoint, because lower weight translates into improved performance of engineered products (i.e., notebook computers are more portable, vehicles achieve better gas mileage, and aircraft can carry more payload). Despite their low density and high strength to weight ratio, however, the widespread implementation of magnesium alloys is currently hindered by their relatively poor corrosion resistance. The objective of this research dissertation is to develop a scientific basis for the creation of a corrosion resistant magnesium alloy. The corrosion resistance of magnesium alloys is affected by several interrelated factors. Among these are alloying, microstructure, impurities, galvanic corrosion effects, and service conditions, among others. Alloying and modification of the microstructure are primary approaches to controlling corrosion. Furthermore, nonequilibrium alloying of magnesium via physical vapor deposition allows for the formation of single-phase magnesium alloys with supersaturated concentrations of passivity-enhancing elements. The microstructure and surface morphology is also modifiable during physical vapor deposition through the variation of evaporation power, pressure, temperature, ion bombardment, and the source-to-substrate distance. Aluminum, titanium, yttrium, and zirconium were initially chosen as candidates likely to impart passivity on vapor deposited magnesium alloys. Prior to this research, alloys of this type have never before been produced, much less studied. All of these metals were observed to afford some degree of corrosion resistance to magnesium. Due to the especially promising results from nonequilibrium alloying of magnesium with yttrium and titanium, the ternary magnesium-yttrium-titanium system was investigated in depth. While all of the alloys are lustrous, surface morphology is observed under the scanning electron microscope. The corrosion rate of the nonequilibrium sputtered alloys, as determined by polarization resistance, is significantly reduced compared to the most corrosion resistant commercial magnesium alloys. The open circuit potentials of the sputter deposited alloys are significantly more noble compared to commercial, equilibrium phase magnesium alloys. Galvanic corrosion susceptibility has also been considerably reduced. Nonequilibrium magnesium-yttrium-titanium alloys have been shown to achieve passivity autonomously by alteration of the composition chemistry of the surface oxide/hydroxide layer. Self-healing properties are also evident, as corrosion propagation can be arrested after initial pitting of the material. A clear relationship exists between the corrosion resistance of sputter vapor deposited magnesium alloys and the amount of ion bombardment incurred by the alloy during deposition. Argon pressure, the distance between the source and the substrate, and alloy morphology play important roles in determining the ability of the alloy to develop a passive film. Thermal effects, both during and after alloy deposition, alter the stress state of the alloys, precipitation of second phases, and the mechanical stability of the passive film. An optimal thermal treatment has been developed in order to maximize the corrosion resistance of the magnesium-yttrium-titanium alloys. The significance of the results includes the acquisition of electrochemical data for these novel materials, as well as expanding the utilization of magnesium alloys by the improvement in their corrosion resistance. The magnesium alloys developed in this work are more corrosion resistant than any commercial magnesium alloy. Structural components comprised of these alloys would therefore exhibit unprecedented corrosion performance. Coatings of these alloys on magnesium components would provide a corrosion resistant yet galvanically-compatible coating. The broad impact of these contributions is that these new low-density, corrosion resistant magnesium alloys can be used to produce engine

  1. Microdiffusers as dynamic passive valves for micropump applications

    Microsoft Academic Search

    Torsten Gerlach

    1998-01-01

    A coherent empiro-theoretical approach to the flow behavior of micro diffuser channels is tried. Microdiffusers may be advantageously employed as dynamic passive valves in micropumps. The central number of merit is the rectification efficiency ? which expresses the flow directing performance of a passive valve. It mainly depends on the aperture angle, relative channel length, throat rounding, flow velocity, and

  2. Analysis of YouTube User Experience from Passive Measurements

    E-print Network

    Politècnica de Catalunya, Universitat

    Analysis of YouTube User Experience from Passive Measurements Giorgos Dimopoulos Pere Barlet}@ac.upc.edu Abstract--In this paper, we analyze the YouTube service and the traffic generated from its usage of collecting these metrics, a tool was developed to perform YouTube traffic measurements by means of passive

  3. Passivity analysis of haptic systems interacting with viscoelastic virtual environment

    Microsoft Academic Search

    Hyoung Il Son; T. Bhattacharjee; Doo Yong Lee

    2009-01-01

    Passivity analysis of any haptic system requires the knowledge of the environment impedance, i.e., parameters of the employed environment model. There have been a few models proposed to describe the viscoelastic behavior of soft tissues, including the popular Maxwell and Voigt models. This paper analyzes passivity of haptic systems interacting with virtual viscoelastic soft tissues. The Kelvin model is employed

  4. PASSIVE TIMESTAMPING IN THE BOUNDED STORAGE MODEL SUBMISSION VERSION

    E-print Network

    Ta-Shma, Amnon

    scheme is passive if a stamper can stamp a document without com­ municating with any other player timestamping schemes were constructed up to date. In this paper we show passive timestamping is possible, a timestamping scheme consists of two mechanisms: A stamping mechanism which allows a user to stamp a document

  5. Passive and Active Acoustics Using an Autonomous Wave Glider

    E-print Network

    Frandsen, Jannette B.

    Passive and Active Acoustics Using an Autonomous Wave Glider developed wave glider has the potential to be an effective unmanned platform for acoustic ap- plications. We of the autonomous platform is evaluated using an integrated passive acoustic recorder during a set of field trials

  6. Passive sonar harmonic detection using feature extraction and clustering analysis

    Microsoft Academic Search

    J. L. Terry; A. Crampton; C. J. Talbot

    2005-01-01

    A current key problem in the development of passive sonar is the classification of data into its different noise sources. This paper focuses on solving the problem using feature extraction and clustering techniques. The methods described in this paper have been developed for data collected from a single sensor omni-directional passive sonar, with the input data being the extracted frequency

  7. Passive acoustic monitoring during the SIRENA 10 cetacean survey

    Microsoft Academic Search

    D. T. Hughes; Jüri Sildam; Arnold B-Nagy; Kendra Ryan; Jeff Haun

    2010-01-01

    This paper discusses passive acoustic monitoring of marine mammals during the Sirena 10 survey. We present results of testing a towed array consisting of 4 broadband hydrophones arranged in a tetrahedral configuration (CPAM-Compact Passive Acoustic Monitoring), for detection, classification and localization of marine mammals. Robust angular determinations of detected signals were possible using time of arrival but range estimation was

  8. Passivity Based Control Of The Compass Gait Biped

    Microsoft Academic Search

    Mark W. Spong

    1999-01-01

    . In this paper we discuss the passivity based control of the two-link robotknown as the Compass Gait Biped. Starting from a narrow region of initial conditions,the compass gait biped is capable of locomotion down shallow inclines without actuationor feedback control of any kind. We will discuss some feedback control strategiesthat can exploit these passive dynamics by shaping the energy

  9. Prediction of passive and active drag in swimming

    Microsoft Academic Search

    Angus Webb; Joseph Banks; lChristopher Phillips; Dominic Hudson; Dominic Taunton; Stephen Turnock

    2011-01-01

    In order to understand the physical origin of passive resistance in swimming the resistance breakdown for a swimmer is investigated. A combination of empirical methods and theoretical analysis is used to predict passive resistance in the speed range 0 – 2ms-1 and is shown to provide similar results to those from experimental testing. Typical magnitudes of wave, viscous pressure and

  10. Zinc recovery and waste sludge minimization from chromium passivation baths

    Microsoft Academic Search

    Nazely Diban; Rosa Mediavilla; Ane Urtiaga; Inmaculada Ortiz

    2011-01-01

    This work reports the feasibility of applying emulsion pertraction technology (EPT) aiming at zinc recovery and waste minimization in the zinc electroplating processes that include Cr (III) passivation. The assessment consists of firstly the lifetime extension of the passivation baths by selective removal of the tramp ions zinc and iron, and secondly, the recovery of zinc for further reuse. Spent

  11. Passivation design for a turbocharged diesel engine model

    Microsoft Academic Search

    Michael Larsen; P. Kokotovic

    1998-01-01

    We show how master\\/slave combinations of multiple inputs may be used for a single-input analysis to overcome obstacles to passivation. This conceptually simple methodology is illustrated by a passivation design for a simplified model of turbocharged diesel engine

  12. Motion Control of Passive Intelligent Walker Using Servo Brakes

    Microsoft Academic Search

    Yasuhisa Hirata; Asami Hara; Kazuhiro Kosuge

    2007-01-01

    We propose a new intelligent walker based on passive robotics that assists the elderly, handicapped people, and the blind who have difficulty in walking. We developed a prototype of the robot technology walker (RT walker), a passive intelligent walker that uses servo brakes. The RT walker consists of a support frame, two casters, two wheels equipped with servo brakes, and

  13. Combined Passive Active Soil Moisture Observations During CLASIC

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An important issue in advancing higher spatial resolution and better accuracy in soil moisture remote sensing is the integration of active and passive observations. In an effort to address these questions an airborne passive/active L-band system (PALS) was flown as part of CLASIC in Oklahoma over th...

  14. A procedure for effective receiver positioning in multistatic passive radar

    Microsoft Academic Search

    Valeria Anastasio; Fabiola Colone; Pierfrancesco Lombardo

    2009-01-01

    Multistatic passive radar systems offer many advantages in terms of coverage and sensitivity of the positioning accuracy with respect to the single bistatic passive radar. However the performance of such a system is largely dependent on the geometry. Its design has to deal with the additional complexity of selecting both the optimum transmitters among the ones available and the optimum

  15. Passivation of silicon power devices by thermal oxidation

    Microsoft Academic Search

    A. Neidig; G. Wahl; K. Weimann; G. Gilbers

    1979-01-01

    A method was developed for the passivation of high voltage silicon power devices replacing the usually applied sensitive silicon polymers on the edge beveling of the pn junctions. The new passivation is produced at temperatures between 600 C and 900 C by thermal oxidation followed by chemical vapor deposition of a barrier layer against alkaline impurities. The barrier layers are

  16. Passive microring-resonator-coupled lasers Ali Shakouri,b)

    E-print Network

    Passive microring-resonator-coupled lasers Bin Liu,a) Ali Shakouri,b) and John E. Bowersc) Calient October 2001 In this letter, a passive microring-resonator-coupled semiconductor laser structure considerably extend the effective cavity length of a conventional Fabry­Perot laser. The side-mode suppression

  17. Passive alignment of optical elements in a printed circuit board

    Microsoft Academic Search

    T. Lamprecht; F. Horst; R. Dangel; R. Beyeler; N. Meier; L. Dellmann; M. Gmur; C. Berger; B. J. Offrein

    2006-01-01

    A successful implementation of optics into PCBs (printed circuit boards) requires a precise passive alignment of optical elements relative to the optical waveguides in the board. We tackled this challenge with a novel concept that allows the passive alignment onto a PCB of any optical or optoelectronic building block with a precision of a few micrometers. Markers, structured into a

  18. Passive Corruption in Statistical Multi-Party Computation

    E-print Network

    Hirt, Martin

    Passive Corruption in Statistical Multi-Party Computation (Extended Abstract) Martin Hirt1 a protocol that toler- ates an adversary corrupting a subset of the parties, preserving certain security guarantees like correctness, secrecy, robustness, and fairness. Corruptions can be either passive or active

  19. Passivity and fuzzy control of singularly perturbed systems

    Microsoft Academic Search

    G. Calcevt; R. GorezS; V. Wertz

    1999-01-01

    It is shown that the passivity of a singularly perturbed system is equivalent to the passivity of both the boundary layer system and the reduced (slow) system. This result is used to formulate a stability condition in terms of LMIs for a nonlinear singularly perturbed system controlled by a Takagi-Sugeno fuzzy controller

  20. Exploiting Passive Dynamics with Variable Stiffness Actuation in Robot Brachiation

    E-print Network

    Vijayakumar, Sethu

    such as energy storage in explosive movements from a viewpoint of performance improvement. Braun et al. [3] have focus on the passive control strategy with variable stiffness actuation for swing movements.nakanishi@ed.ac.uk, sethu.vijayakumar@ed.ac.uk Abstract--This paper explores a passive control strategy with variable

  1. Myoelectric silence following unopposed passive stretch in normal man

    Microsoft Academic Search

    R W Angel; S G Waxman; J D Kocsis

    1980-01-01

    The response to unopposed passive muscle stretch applied during sustained contraction was studied in normal man. When the subject did not resist the stretching force, the initial response was a brief cessation of EMG activity in the elongated muscle. The myoelectric silence was observed repeatedly in muscles of the upper and lower limbs. The response to passive stretch is discussed

  2. Long Range Passive UHF RFID System Using HVAC Ducts

    E-print Network

    Hochberg, Michael

    INVITED P A P E R Long Range Passive UHF RFID System Using HVAC Ducts To provide a potential communications channel, HVAC ducts can function as electromagnetic waveguides; a 30-m read range has been-conditioning (HVAC) ducts as a potential communication channel between passive ultrahigh-frequency (UHF) radio

  3. Liquid metal cooled nuclear reactors with passive cooling system

    DOEpatents

    Hunsbedt, Anstein (Los Gatos, CA); Fanning, Alan W. (San Jose, CA)

    1991-01-01

    A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of cooling medium flow circuits which cooperate to remove and carry heat away from the fuel core upon loss of the normal cooling flow circuit to areas external thereto.

  4. Developmental Perspectives on the Acquisition of the Passive

    ERIC Educational Resources Information Center

    Crawford, Jean Lenore

    2012-01-01

    This dissertation investigates the acquisition of the passive. The apparent cross-linguistic delay of the verbal passive compared to other constructions suggests children's knowledge is somehow restricted, leading some to propose the difficulty arises because of syntactic maturation (Wexler 2004, Orfitelli 2012) or because of a heavy reliance…

  5. Countering stealth with passive, multi-static, low frequency radars

    Microsoft Academic Search

    H. Kuschel; J. Heckenbach; S. Mu?ller; R. Appel

    2010-01-01

    The potential of passive, multi-static radars as covert sensors for the detection of low flying, stealth air targets are illustrated by multi-static RCS analysis, coverage simulations for low flight levels and measurement results obtained with an experimental passive radar using digital audio broadcast signals (DAB). The measurement sensor is described and future perspectives are pointed out.

  6. Passivation of pigment particles for thermal control coatings

    NASA Technical Reports Server (NTRS)

    Sancier, K. M.; Morrison, S. R.; Farley, E. P.

    1974-01-01

    Various redox couple surface additives are studied which increase the photostability of coprecipitated zinc orthotitanate pigment. The electron spin resonance technique was used to examine the characteristic photodamage centers. Results indicate that cerium surface redox additive completely passivates the pigment at the surface concentrations studied. Less passivation occurs with the iridium chloride and the iron cyanide redox couples.

  7. Passive ice freezing-releasing heat pipe. [Patent application

    DOEpatents

    Gorski, A.J.; Schertz, W.W.

    1980-09-29

    A heat pipe device has been developed which permits completely passive ice formation and periodic release of ice without requiring the ambient temperature to rise above the melting point of water. This passive design enables the maximum amount of cooling capacity to be stored in the tank.

  8. THE IMPACT OF PASSIVE SAMPLING METHODOLOGIES USED IN THE DEARS

    EPA Science Inventory

    This abstract details the use of passive sampling methodologies in the Detroit Exposure and Aerosol Research Study (DEARS). A discussion about the utility of various gas-phase passive samplers used in the study will be described along with examples of field data measurements empl...

  9. Passive-adaptive vibration absorbers using shape memory alloys

    Microsoft Academic Search

    Keith A. Williams; George T. Chiu; Robert Bernhard

    1999-01-01

    The passive-adaptive approach to vibration control shows promise in its ability to combine the robust stability and low-complexity of passive tuned absorbers with the adaptability of active control schemes. Previous tunable vibration absorbers have been complex and bulky. Shape memory alloys (SMA) with their variable material properties, offer an alternative adaptive mechanism. Heating an SMA causes a change in the

  10. Passive magnetic bearing for flywheel energy storage systems

    Microsoft Academic Search

    Alexei V. Filatov; Eric H. Maslen

    2001-01-01

    This paper proposes a novel type of passive noncontact magnetic suspension. An advantageous feature of passive suspension systems is that they are intrinsically stable, in contrast to active magnetic bearings and therefore can provide much higher reliability, which is known to be the crucial factor in applications requiring continuous noncontact suspension of high-speed rotors. An example of such an application

  11. Test results: textiles selected for direct gain passive buildings

    SciTech Connect

    Guerin, D.A.; Butler, S.L.

    1981-01-01

    Upholstery textiles that are commercially available to residents of passive solar homes were tested to determine the sunlight resistance and thermal conductivity properties. Those textiles with the highest rating for sunlight resistance can then be recommended for use in direct gain passive solar buildings.

  12. Reward dominance and passive avoidance learning in adolescent psychopaths

    Microsoft Academic Search

    Angela Scerbo; Adrian Raine; Mary O'Brien; Cheryl-Jean Chan; Cathy Rhee; Norine Smiley

    1990-01-01

    This study tests predictions that adolescent psychopaths are hyperresponsive to rewards (Quay, 1988) and deficient in passive avoidance learning (Newman & Kosson, 1986). Forty male adolescent juvenile offenders were divided into psychopaths and nonpsychopaths using cluster analysis. Subjects were administered a passive avoidance learning task which required learning when to respond to cards associated with either reward or punishment. Results

  13. Amplitude of muscle stretch modulates corticomotor gain during passive movement

    Microsoft Academic Search

    James P. Coxon; James W. Stinear; Winston D. Byblow

    2005-01-01

    Previous studies have shown that the excitability of corticomotor projections to forearm muscles exhibit phasic modulation during passive movement (flexion–extension) about the wrist joint. We examined the stimulus–response properties of flexor carpi radialis (FCR) and extensor carpi radialis (ECR) to transcranial magnetic stimulation (TMS) applied over the contralateral motor cortex while the wrist was moved passively at two different sinusoidal

  14. Airborne validation of an IR passive TBM ranging sensor

    Microsoft Academic Search

    Dennis L. McKay; Martin R. Wohlers; Chiu-Kuang Chuang; James S. Draper; James Walker

    1999-01-01

    Monocular Passive Ranging (MPR) employs a single multicolor IR sensor to passively range to a boosting theater ballistic missile (TBM). Airborne active ranging sensor, such as radars and ladars, may attract anti-radiation missiles, and are forced to large standoff distances. Thus, they may not be positioned to give adequate early warning of a missile launch, Estimation of launch position, or

  15. Large Scale Simulation of Tor: Modelling a Global Passive Adversary

    Microsoft Academic Search

    Gavin O' Gorman; Stephen Blott

    Implementing global passive adversary attacks on currently deployed low latency anonymous networks is not feasible. This paper describes the implementation of a large scale, discrete event based sim- ulation of Tor, using the SSFNet simulator. Several global passive ad- versary attacks are implemented on a simulated Tor network comprised of approximately 6000 nodes. The attacks prove to be highly accurate

  16. Using Passive Cavitation Detection to Observe Postexcitation Response of Ultrasound Contrast

    E-print Network

    Illinois at Urbana-Champaign, University of

    Using Passive Cavitation Detection to Observe Postexcitation Response of Ultrasound Contrast Agents, FR Email: daking3@illinois.edu Abstract-- Passive cavitation detection was used to improve. Keywords - microbubbles; postexcitation; passive cavitation detection; inertial cavitation; flow rate I

  17. 26 CFR 1.469-3T - Passive activity credit (temporary).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...deductions 123,950 Passive activity deductions 18...tax liability allocable to passive activities for 1988 is zero. Although B's net operating loss for the taxable...is reduced by B's net passive income, and B's...

  18. 48 CFR 552.211-92 - Radio Frequency Identification (RFID) using passive tags.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...false Radio Frequency Identification (RFID) using passive tags. 552.211-92...211-92 Radio Frequency Identification (RFID) using passive tags. As prescribed...clause: Radio Frequency Identification (RFID) Using Passive Tags (JAN...

  19. 48 CFR 552.211-92 - Radio Frequency Identification (RFID) using passive tags.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...false Radio Frequency Identification (RFID) using passive tags. 552.211-92...211-92 Radio Frequency Identification (RFID) using passive tags. As prescribed...clause: Radio Frequency Identification (RFID) Using Passive Tags (JAN...

  20. Influence of free air space on microbial kinetics in passively aerated compost.

    PubMed

    Yu, Shouhai; Clark, O Grant; Leonard, Jerry J

    2009-01-01

    The influence of free air space (FAS) on passively aerated composting has been reported, but the quantitative relationship between FAS and the microbial kinetics in passively aerated compost has not been investigated. This relationship was studied by composting dairy manure and straw in an enclosed, passively aerated, cylindrical vessel. Based on this experimental system, conceptual and numerical models were developed in which the compost bed was considered to consist of layered elements, each being physically and chemically homogeneous. The microbial activity in each layer was represented in order to predict oxygen and substrate consumption and the release of water and heat. Convective transport of air, moisture, and heat through the layers was represented. Microbial growth and substrate consumption rates were described using modified first-order kinetics for each of the mesophilic and thermophilic temperature regimes. The values of the microbial kinetic parameters were adjusted for each layer based on an innovative, non-linear, statistical analysis of temperature histories recorded at different layers in the compost bed during three treatments (i.e., FAS values of 0.45, 0.52, and 0.65). Microbial kinetic rate constants were found to follow a sigmoid relationship with FAS, with correlation coefficients (R(2)) of 0.97 for the mesophilic stage and 0.96 for the thermophilic stage. Temperature histories and airflow measurements from a fourth treatment (FAS value of 0.57) were used as an independent check of the model's performance. Simulation results indicate that the model could predict the general trend of temperature development. A plot of the residuals shows that the model is biased, however, possibly because many parameters in the model were not measured directly but instead were estimated from literature. The result from this study demonstrates a new method for describing the relationship between microbial kinetics (k(max)) and substrate FAS, which could be used to improve the design, optimization, and management of passively aerated composting facilities. PMID:18710800