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1

Childhood Temperament: Passive Gene-Environment Correlation, Gene-Environment Interaction, and the Hidden Importance of the Family Environment  

PubMed Central

Biological parents pass on genotypes to their children, as well as provide home environments that correlate with their genotypes; thus, the association between the home environment and children's temperament can be genetically (i.e. passive gene-environment correlation) or environmentally mediated. Furthermore, family environments may suppress or facilitate the heritability of children's temperament (i.e. gene-environment interaction). The sample comprised 807 twin pairs (M age = 7.93 years) from the longitudinal Wisconsin Twin Project. Important passive gene-environment correlations emerged, such that home environments were less chaotic for children with high Effortful Control, and this association was genetically mediated. Children with high Extraversion/Surgency experienced more chaotic home environments, and this correlation was also genetically mediated. In addition, heritability of children's temperament was moderated by home environments, such that Effortful Control and Extraversion/Surgency were more heritable in chaotic homes, and Negative Affectivity was more heritable under crowded or unsafe home conditions. Modeling multiple types of gene-environment interplay uncovered the complex role of genetic factors and the hidden importance of the family environment for children's temperament and development more generally. PMID:23398752

Lemery-Chalfant, Kathryn; Kao, Karen; Swann, Gregory; Goldsmith, H. Hill

2013-01-01

2

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

ERIC Educational Resources Information Center

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…

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

2013-01-01

3

Effects of the Family Environment: Gene-Environment Interaction and Passive Gene-Environment Correlation  

ERIC Educational Resources Information Center

The classical twin study provides a useful resource for testing hypotheses about how the family environment influences children's development, including how genes can influence sensitivity to environmental effects. However, existing statistical models do not account for the possibility that children can inherit exposure to family environments…

Price, Thomas S.; Jaffee, Sara R.

2008-01-01

4

Gene–Environment Correlation: Difficulties and a Natural Experiment–Based Strategy  

PubMed Central

Objectives. We explored how gene–environment correlations can result in endogenous models, how natural experiments can protect against this threat, and if unbiased estimates from natural experiments are generalizable to other contexts. Methods. We compared a natural experiment, the College Roommate Study, which measured genes and behaviors of college students and their randomly assigned roommates in a southern public university, with observational data from the National Longitudinal Study of Adolescent Health in 2008. We predicted exposure to exercising peers using genetic markers and estimated environmental effects on alcohol consumption. A mixed-linear model estimated an alcohol consumption variance that was attributable to genetic markers and across peer environments. Results. Peer exercise environment was associated with respondent genotype in observational data, but not in the natural experiment. The effects of peer drinking and presence of a general gene–environment interaction were similar between data sets. Conclusions. Natural experiments, like random roommate assignment, could protect against potential bias introduced by gene–environment correlations. When combined with representative observational data, unbiased and generalizable causal effects could be estimated. PMID:23927502

Li, Jiang; Liu, Hexuan; Guo, Guang

2013-01-01

5

The genetics of music accomplishment: Evidence for gene-environment correlation and interaction.  

PubMed

Theories of skilled performance that emphasize training history, such as K. Anders Ericsson and colleagues' deliberate-practice theory, have received a great deal of recent attention in both the scientific literature and the popular press. Twin studies, however, have demonstrated evidence for moderate-to-strong genetic influences on skilled performance. Focusing on musical accomplishment in a sample of over 800 pairs of twins, we found evidence for gene-environment correlation, in the form of a genetic effect on music practice. However, only about one quarter of the genetic effect on music accomplishment was explained by this genetic effect on music practice, suggesting that genetically influenced factors other than practice contribute to individual differences in music accomplishment. We also found evidence for gene-environment interaction, such that genetic effects on music accomplishment were most pronounced among those engaging in music practice, suggesting that genetic potentials for skilled performance are most fully expressed and fostered by practice. PMID:24957535

Hambrick, David Z; Tucker-Drob, Elliot M

2015-02-01

6

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

PubMed Central

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

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

2013-01-01

7

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

PubMed

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

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

2012-06-01

8

Evocative gene-environment correlation in the mother-child relationship: a twin study of interpersonal processes.  

PubMed

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

Klahr, Ashlea M; Thomas, Katherine M; Hopwood, Christopher J; Klump, Kelly L; Burt, S Alexandra

2013-02-01

9

The Heritability of Personality is not Always 50%: Gene-Environment Interactions and Correlations between Personality and Parenting  

PubMed Central

Twin studies of personality are consistent in attributing approximately half of the variance in personality to genetic effects, with the remaining variance attributed to environments that make people within the same families different. Such conclusions, however, are based on quantitative models of human individual differences that estimate genetic and environmental contributions as constants for entire populations. Recent advances in statistical modeling allow for the possibility of estimating genetic and environmental contributions contingent on other variables, allowing the quantification of phenomena that have traditionally been characterized as gene-environment interaction and correlation. We applied these newer models to understand how adolescents’ descriptions of their relationships with their parents might change or moderate the impact of genetic and environmental factors on personality. We documented notable moderation in the domains of positive and negative emotionality, with parental relationships acting to both enhance and diminish both genetic and environmental effects. We discuss how genetic and environmental contributions to personality might be more richly conceptualized as dynamic systems of gene-environment interplay – systems that are not captured by classical concepts, such as the overall heritability of personality. PMID:19012656

Krueger, Robert F.; South, Susan; Johnson, Wendy; Iacono, William

2008-01-01

10

Natural genetic variation in social environment choice: context-dependent gene-environment correlation in Drosophila melanogaster.  

PubMed

Gene-environment correlation (rGE) occurs when an individual's genotype determines its choice of environment, generating a correlation between environment and genotype frequency. In particular, social rGE, caused by genetic variation in social environment choice, can critically determine both individual development and the course of social selection. Despite its foundational role in social evolution and developmental psychology theory, natural genetic variation in social environment choice has scarcely been examined empirically. Drosophila melanogaster provides an ideal system for investigating social rGE. Flies live socially in nature and have many opportunities to make social decisions; and natural, heterozygous genotypes may be replicated, enabling comparisons between genotypes across environments. Using this approach, I show that all aspects of social environment choice vary among natural genotypes, demonstrating pervasive social rGE. Surprisingly, genetic variation in group-size preference was density dependent, indicating that the behavioral and evolutionary consequences of rGE may depend on the context in which social decisions are made. These results provide the first detailed investigation of social rGE, and illustrate that that genetic variation may influence organismal performance by specifying the environment in which traits are expressed. PMID:21790578

Saltz, Julia B

2011-08-01

11

Adolescent Peer Choice and Cigarette Smoking: Evidence of Active Gene-Environment Correlation?  

PubMed Central

Both peer groups and genetics have been associated with adolescent smoking behavior. Recently, Loehlin (2010) reported that twin differences in alcohol use were associated with differences in the number of common friends. Twins with more friends in common were more similar in drinking, but only for DZ pairs. Using the same sample as Loehlin (the National Merit twins), we replicated all of these findings for a composite cigarette smoking measure and for smoking initiation, but not persistence. The pattern of results is most consistent with homophily, or the tendency to associate with individuals that are like oneself. If peer influence occurs in the presence of homophily, then active genotype-environment correlation will be induced. PMID:23924806

Wills, Amanda G.; Carey, Gregory

2014-01-01

12

The Interacting Effect of the BDNF Val66Met Polymorphism and Stressful Life Events on Adolescent Depression Is Not an Artifact of Gene-Environment Correlation: Evidence from a Longitudinal Twin Study  

ERIC Educational Resources Information Center

Background: Confounding introduced by gene-environment correlation (rGE) may prevent one from observing a true gene-environment interaction (G × E) effect on psychopathology. The present study investigated the interacting effect of the BDNF Val66Met polymorphism and stressful life events (SLEs) on adolescent depression while controlling for the…

Chen, Jie; Li, Xinying; McGue, Matt

2013-01-01

13

Neural correlates of processing passive sentences.  

PubMed

Previous research has shown that comprehension of complex sentences involving wh-movement (e.g., object-relative clauses) elicits activation in the left inferior frontal gyrus (IFG) and left posterior temporal cortex. However, relatively little is known about the neural correlates of processing passive sentences, which differ from other complex sentences in terms of representation (i.e., noun phrase (NP)-movement) and processing (i.e., the time course of syntactic reanalysis). In the present study, 27 adults (14 younger and 13 older) listened to passive and active sentences and performed a sentence-picture verification task using functional Magnetic Resonance Imaging (fMRI). Passive sentences, relative to active sentences, elicited greater activation in bilateral IFG and left temporo-occipital regions. Participant age did not significantly affect patterns of activation. Consistent with previous research, activation in left temporo-occipital cortex likely reflects thematic reanalysis processes, whereas, activation in the left IFG supports processing of complex syntax (i.e., NP-movement). Right IFG activation may reflect syntactic reanalysis processing demands associated with the sentence-picture verification task. PMID:24961525

Mack, Jennifer E; Meltzer-Asscher, Aya; Barbieri, Elena; Thompson, Cynthia K

2013-01-01

14

Neural Correlates of Processing Passive Sentences  

PubMed Central

Previous research has shown that comprehension of complex sentences involving wh-movement (e.g., object-relative clauses) elicits activation in the left inferior frontal gyrus (IFG) and left posterior temporal cortex. However, relatively little is known about the neural correlates of processing passive sentences, which differ from other complex sentences in terms of representation (i.e., noun phrase (NP)-movement) and processing (i.e., the time course of syntactic reanalysis). In the present study, 27 adults (14 younger and 13 older) listened to passive and active sentences and performed a sentence-picture verification task using functional Magnetic Resonance Imaging (fMRI). Passive sentences, relative to active sentences, elicited greater activation in bilateral IFG and left temporo-occipital regions. Participant age did not significantly affect patterns of activation. Consistent with previous research, activation in left temporo-occipital cortex likely reflects thematic reanalysis processes, whereas, activation in the left IFG supports processing of complex syntax (i.e., NP-movement). Right IFG activation may reflect syntactic reanalysis processing demands associated with the sentence-picture verification task. PMID:24961525

Mack, Jennifer E.; Meltzer-Asscher, Aya; Barbieri, Elena; Thompson, Cynthia K.

2013-01-01

15

Gene-Environment Interdependence  

ERIC Educational Resources Information Center

Behavioural genetics was initially concerned with partitioning population variance into that due to genetics and that due to environmental influences. The implication was that the two were separate and it was assumed that gene-environment interactions were usually of so little importance that they could safely be ignored. Theoretical…

Rutter, Michael

2007-01-01

16

Evidence of gene-environment correlation for peer difficulties: disruptive behaviors predict early peer relation difficulties in school through genetic effects.  

PubMed

Early disruptive behaviors, such as aggressive and hyperactive behaviors, known to be influenced by genetic factors, have been found to predict early school peer relation difficulties, such as peer rejection and victimization. However, there is no consensus regarding the developmental processes underlying this predictive association. Genetically informative designs, such as twin studies, are well suited for investigating the underlying genetic and environmental etiology of this association. The main goal of the present study was to examine the possible establishment of an emerging gene-environment correlation linking disruptive behaviors to peer relationship difficulties during the first years of school. Participants were drawn from an ongoing longitudinal study of twins who were assessed with respect to their social behaviors and their peer relation difficulties in kindergarten and in Grade 1 through peer nominations measures and teacher ratings. As predicted, disruptive behaviors were concurrently and predictively associated with peer relation difficulties. Multivariate analyses of these associations indicate that they were mainly accounted for by genetic factors. These results emphasize the need to adopt an early and persistent prevention framework targeting both the child and the peer context to alleviate the establishment of a negative coercive process and its consequences. PMID:23398754

Boivin, Michel; Brendgen, Mara; Vitaro, Frank; Forget-Dubois, Nadine; Feng, Bei; Tremblay, Richard E; Dionne, Ginette

2013-02-01

17

Gene-Environment Interplay in Twin Models.  

PubMed

In this article, we respond to Shultziner's critique that argues that identical twins are more alike not because of genetic similarity, but because they select into more similar environments and respond to stimuli in comparable ways, and that these effects bias twin model estimates to such an extent that they are invalid. The essay further argues that the theory and methods that undergird twin models, as well as the empirical studies which rely upon them, are unaware of these potential biases. We correct this and other misunderstandings in the essay and find that gene-environment (GE) interplay is a well-articulated concept in behavior genetics and political science, operationalized as gene-environment correlation and gene-environment interaction. Both are incorporated into interpretations of the classical twin design (CTD) and estimated in numerous empirical studies through extensions of the CTD. We then conduct simulations to quantify the influence of GE interplay on estimates from the CTD. Due to the criticism's mischaracterization of the CTD and GE interplay, combined with the absence of any empirical evidence to counter what is presented in the extant literature and this article, we conclude that the critique does not enhance our understanding of the processes that drive political traits, genetic or otherwise. PMID:24808718

Verhulst, Brad; Hatemi, Peter K

2013-07-01

18

Genes, Environment, and Human Behavior.  

ERIC Educational Resources Information Center

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…

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

19

Correlation between lidar-derived intensity and passive optical imagery  

NASA Astrophysics Data System (ADS)

When LiDAR data are collected, the intensity information is recorded for each return, and can be used to produce an image resembling those acquired by passive imaging sensors. This research evaluated LiDAR intensity data to determine its potential for use as baseline imagery where optical imagery are unavailable. Two airborne LiDAR datasets collected at different point densities and laser wavelengths were gridded and compared with optical imagery. Optech Orion C200 laser data were compared with a corresponding 1541 nm spectral band from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). Optech ALTM Gemini LiDAR data collected at 1064 nm were compared to the WorldView-2 (WV-2) 949 - 1043 nm NIR2 band. Intensity images were georegistered and spatially resampled to match the optical data. The Pearson Product Moment correlation coefficient was calculated between datasets to determine similarity. Comparison for the full LiDAR datasets yielded correlation coefficients of approximately 0.5. Because LiDAR returns from vegetation are known to be highly variable, a Normalized Difference Vegetation Index (NDVI) was calculated utilizing the optical imagery, and intensity and optical imagery were separated into vegetation and nonvegetation categories. Comparison of the LiDAR intensity for non-vegetated areas to the optical imagery yielded coefficients greater than 0.9. These results demonstrate that LiDAR intensity data may be useful in substituting for optical imagery where only LiDAR is available.

Metcalf, Jeremy P.; Kim, Angela M.; Kruse, Fred A.; Olsen, Richard C.

2014-06-01

20

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

E-print Network

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

Garnier, Josselin

21

Genes, Environments, and Behavior 2  

NSDL National Science Digital Library

In this lesson students will study how genetic research on behavior is conducted. Genes, Environment, and Behavior 2 is the second 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. Genes, Environment and Behavior 2 introduces students to the various approaches scientists use to explore the interaction of genetic and environmental forces which shape behavior.An important objective of these lessons is to help students overcome the common public misperception that genes can have a direct relationship with behavior; for example, that there may be a "gene for criminality" or a "gene for religiosity." Another common misperception that can be dispelled through these lessons is that the development of an organism is determined solely by genetic factors; this is called genetic determinism. Possibly the most important value of these lessons, therefore, is that they can help students understand why such beliefs are false.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. Students will also perform a scavenger hunt on a scientific research article for phrases that reference research methods including: family studies, molecular studies, and brain imaging studies.

American Association for the Advancement of Science (;)

2006-04-25

22

Gene-Environment Interplay, Family Relationships, and Child Adjustment  

ERIC Educational Resources Information Center

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…

Horwitz, Briana N.; Neiderhiser, Jenae M.

2011-01-01

23

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

ERIC Educational Resources Information Center

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…

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

2014-01-01

24

Gene–environment interactions in human diseases  

Microsoft Academic Search

Studies of gene–environment interactions aim to describe how genetic and environmental factors jointly influence the risk of developing a human disease. Gene–environment interactions can be described by using several models, which take into account the various ways in which genetic effects can be modified by environmental exposures, the number of levels of these exposures and the model on which the

David J. Hunter

2005-01-01

25

Genes, Environments, and Behavior 1  

NSDL National Science Digital Library

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?"

American Association for the Advancement of Science (;)

2006-04-25

26

Gene-environment interactions in mental disorders  

PubMed Central

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

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

2004-01-01

27

Benefits of Time Correlation Measurements for Passive Screening  

NASA Astrophysics Data System (ADS)

The “FLASH Portals Project” is a collaboration between Arktis Radiation Detectors Ltd (CH), the Atomic Weapons Establishment (UK), and the Joint Research Centre (European Commission), supported by the Technical Support Working Group (TSWG). The program's goal was to develop and demonstrate a technology to detect shielded special nuclear materials (SNM) more efficiently and less ambiguously by exploiting time correlation. This study presents experimental results of a two-sided portal monitor equipped with in total 16 4He fast neutron detectors as well as four polyvinyltoluene (PVT) plastic scintillators. All detectors have been synchronized to nanosecond precision, thereby allowing the resolution of time correlations from timescales of tens of microseconds (such as (n, ?) reactions) down to prompt fission correlations directly. Our results demonstrate that such correlations can be detected in a typical radiation portal monitor (RPM) geometry and within operationally acceptable time scales, and that exploiting these signatures significantly improves the performance of the RPM compared to neutron counting. Furthermore, the results show that some time structure remains even in the presence of heavy shielding, thus significantly improving the sensitivity of the detection system to shielded SNM.

Murer, David; Blackie, Douglas; Peerani, Paolo

2014-02-01

28

Passive elastography: shear-wave tomography from physiological-noise correlation in soft tissues.  

PubMed

Inspired by seismic-noise correlation and time reversal, a shear-wave tomography of soft tissues using an ultrafast ultrasonic scanner is presented here. Free from the need for controlled shear-wave sources, this passive elastography is based on Green's function retrieval and takes advantage of the permanent physiological noise of the human body. PMID:21693392

Gallot, Thomas; Catheline, Stefan; Roux, Philippe; Brum, Javier; Benech, Nicolas; Negreira, Carlos

2011-06-01

29

Simulation of GPR passive interferometry using cross-correlation for LNAPL model monitoring application  

NASA Astrophysics Data System (ADS)

Passive interferometry technology 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 ambient noise source in the subsurface with the cross-correlation (CC) or multidimensional deconvolution methods. We investigate the feasibility of electromagnetic (EM) wave passive interferometry with CC method. We design a 2-D finite-difference time domain (FDTD) algorithm to simulate the long-duration ground penetrating radar (GPR) measurements with random distribution of passive EM sources. The noise sources have random duration time, waveform and spatial distribution. We test the FDTD GPR passive interferometry code with above source characteristics and apply the method to light non-aqueous phase liquid (LNAPL) monitoring. Based on the model simulation data, by using common midpoint velocity analysis and normal move out correction to process the interferometry retrieve record, we can accurately obtain the dynamic changing characteristics of the target's permittivity. The LNAPL dynamic leakage model can be imaged as well. The synthetic results demonstrate that the GPR passive interferometry is feasible in subsurface LNAPL monitoring. Our work provides a foundation for a passive interferometry field application using GPR.

Li, Jing; Zeng, Zhaofa; Slob, Evert; Chen, Xiong; Liu, Fengshan

2014-12-01

30

Gene-Environment Studies and Borderline Personality Disorder: A Review  

PubMed Central

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

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

2014-01-01

31

Passive dispersion analysis on a sea dike using cross-correlations and beamforming  

NASA Astrophysics Data System (ADS)

In order to passively infer the velocities of surface waves beneath a receiver array, we propose to apply beamforming on cross-correlated noise records. We test the method with synthetic signals generated for a variety of array geometries and noise distributions. We show that the use of cross-correlations cleans the dispersion diagram that would be obtained from a phase-shift analysis alone, by resolving ambiguities between the location of noise sources and the wave velocities. In particular, when nearby noise sources are present, accurate dispersion curves can be inferred from arrays possessing poor azimuthal coverages. This passive method is therefore appropriate for the monitoring of stiffness at the civil-engineering scale, where multiple isolated noise sources may be present and where the field geometry does not always allow to deploy circular arrays. We apply the method to field data obtained from a linear array installed on top of a sea dike. The seismic noise, recorded at high tide during 8 minutes, is essentially generated by impacts of sea waves. In contrast to a phase-shift analysis performed on the noise itself, we show that the use of cross-correlations allow to infer a dispersion curve consistent with an active hammer-shot measurement, in a larger frequency band, ranging from 5 to 55 Hz. This result opens the possibility of following passively the mechanical evolution of embankments on a daily basis.

Le Feuvre, Mathieu; Joubert, Anaëlle; Leparoux, Donatienne; Côte, Philippe

2014-05-01

32

Biological Implications of Gene-Environment Interaction  

ERIC Educational Resources Information Center

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…

Rutter, Michael

2008-01-01

33

Correlation between density and oxidation temperature for pyrolytic-gas passivated ultrathin silicon oxide films  

NASA Astrophysics Data System (ADS)

Pyrolytic-gas passivation (PGP) with a small amount nitrogen gas enhances the breakdown reliability of silicon oxide gate films. To clarify the reliability retention of the PGP-grown films oxidized at low temperature, densities (?ox's) of the 3.5-6.5-nm-thick PGP-grown films on Si(100) oxidized at 700-900 °C were investigated. Since ?ox's correlate well with the reliability and are useful as an index of the intrinsic structural characteristics of the films. Moreover, changes in ?ox and nitrogen content corresponding to oxidation temperature are similar to those in breakdown reliability and interface state density (Dit), respectively. In addition, ?ox's of the 700 °C-grown PGP films do not deteriorate as much when compared with those of the films grown by normal ultradry oxidation at 800 °C and their Dit's are less than about 6×1010/eV cm2. This suggests that PGP probably improves the reliability by generating the higher-?ox microscopic structure with few Si dangling bonds and effective passivation. .

Yamada, Hiroshi

2004-01-01

34

Gene–environment interactions in psychiatry: joining forces with neuroscience  

Microsoft Academic Search

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

Avshalom Caspi; Terrie E. Moffitt

2006-01-01

35

Correlation between repassivation kinetics and corrosion rate over a passive surface in flowing slurry  

Microsoft Academic Search

The effect of hydrodynamics of flowing slurry on anodic dissolution rate of passive metals was quantitatively evaluated using a theoretical model recently developed by the authors. The enhanced anodic dissolution over a passive metal in flowing slurry is dominated by the passive film breakdown caused by the impingement of solid particles and the decay of local current density over the

B. T. Lu; J. L. Luo; F. Mohammadi; K. Wang; X. M. Wan

2008-01-01

36

Neuronal Correlates of a Virtual-Reality-Based Passive Sensory P300 Network  

PubMed Central

P300, a positive event-related potential (ERP) evoked at around 300 ms after stimulus, can be elicited using an active or passive oddball paradigm. Active P300 requires a person’s intentional response, whereas passive P300 does not require an intentional response. Passive P300 has been used in incommunicative patients for consciousness detection and brain computer interface. Active and passive P300 differ in amplitude, but not in latency or scalp distribution. However, no study has addressed the mechanism underlying the production of passive P300. In particular, it remains unclear whether the passive P300 shares an identical active P300 generating network architecture when no response is required. This study aims to explore the hierarchical network of passive sensory P300 production using dynamic causal modelling (DCM) for ERP and a novel virtual reality (VR)-based passive oddball paradigm. Moreover, we investigated the causal relationship of this passive P300 network and the changes in connection strength to address the possible functional roles. A classical ERP analysis was performed to verify that the proposed VR-based game can reliably elicit passive P300. The DCM results suggested that the passive and active P300 share the same parietal-frontal neural network for attentional control and, underlying the passive network, the feed-forward modulation is stronger than the feed-back one. The functional role of this forward modulation may indicate the delivery of sensory information, automatic detection of differences, and stimulus-driven attentional processes involved in performing this passive task. To our best knowledge, this is the first study to address the passive P300 network. The results of this study may provide a reference for future clinical studies on addressing the network alternations under pathological states of incommunicative patients. However, caution is required when comparing patients’ analytic results with this study. For example, the task presented here is not applicable to incommunicative patients. PMID:25401520

Chen, Chun-Chuan; Syue, Kai-Syun; Li, Kai-Chiun; Yeh, Shih-Ching

2014-01-01

37

Passive Skeletal Muscle Excursion after Tendon Rupture Correlates with Increased Collagen Content in Muscle  

PubMed Central

Purpose This study was designed to measure time-dependent changes in muscle excursion and collagen content after tenotomy, and to analyze the correlation between muscle excursion and collagen content in a rabbit model. Materials and Methods Twenty-four rabbits underwent tenotomy of the second extensor digitorum longus (EDL) muscles on the right legs and were randomly assigned to three groups based on the period of time after tenotomy (2, 4, and 6 weeks). The second EDL muscles on left legs were used as controls. At each time after tenotomy, passive muscle excursion and collagen content, determined by hydroxyproline content, were measured bilaterally, and the ratio of each value to the normal one was used. Results The mean ratio of muscle excursion after tenotomy to the value of the control decreased in a time-dependent fashion: 92.5% at 2 weeks, 78.6% at 4 weeks, and 55.1% at 6 weeks. The mean ratio of hydroxyproline content in muscle to the value of the control increased in a time-dependent fashion: 119.5% at 2 weeks, 157.3% at 4 weeks, and 166.6% at 6 weeks. There was a significant negative correlation between the ratio of hydroxyproline content in muscle after tenotomy to the control values and the ratio of muscle excursion after tenotomy to the control values (r=-0.602, p=0.002). Conclusion The decrease in muscle excursion seems to correlate with the increase in collagen content in the muscle in a time-dependent fashion following tenotomy. PMID:25048502

Koh, Il Hyun; Kang, Ho Jung; Jeon, Sang Woo; Park, Jae Han

2014-01-01

38

Gene × environment interaction models in psychiatric genetics.  

PubMed

Gene-environment (G × E) interaction research is an emerging area in psychiatry, with the number of G × E studies growing rapidly in the past two decades. This article aims to give a comprehensive introduction to the field, with an emphasis on central theoretical and practical problems that are worth considering before conducting a G × E interaction study. On the theoretical side, we discuss two fundamental, but controversial questions about (1) the validity of statistical models for biological interaction and (2) the utility of G × E research for psychiatric genetics. On the practical side, we focus on study characteristics that potentially influence the outcome of G × E interaction studies and discuss strengths and pitfalls of different study designs, including recent approaches like Genome-Environment Wide Interaction Studies (GEWIS). Finally, we discuss recent developments in G × E interaction research on the most heavily investigated example in psychiatric genetics, the interaction between a serotonin transporter gene promoter variant (5-HTTLPR) and stress on depression. PMID:22241248

Karg, Katja; Sen, Srijan

2012-01-01

39

Resilience and measured gene-environment interactions.  

PubMed

The past decade has witnessed an exponential growth in studies that have attempted to identify the genetic polymporphisms that moderate the influence of environmental risks on mental disorders. What tends to be neglected in these Gene × Environment (G × E) interaction studies has been a focus on resilience, which refers to a dynamic pattern of positive adaptation despite the experience of a significant trauma or adversity. In this article, we argue that one step toward advancing the field of developmental psychopathology would be for G × E research to consider resilience instead of focusing almost exclusively on mental disorders. After providing an up-to-date summary on the expanding definitions and models of resilience, and the available evidence regarding measured G × E studies of childhood maltreatment, we discuss why resilience would be a worthwhile phenotype for studies of measured G × E. First, although G × E hypotheses require that there be an environmental risk (e-risk) involved in a causal process that leads to psychopathology, e-risks are typically not included in the diagnostic criteria for most psychiatric disorders. In contrast, resilience by definition includes an e-risk. Second, G × E hypotheses require that there is evidence of variability in response to an environmental stressor, and resilience often represents the positive end on this continuum of adaptation. Third, both resilience and G × E are best understood from a developmental perspective. Fourth, although resilient outcomes are not public health concerns, the types of adversities (e.g., childhood maltreatment, poverty, or exposure to natural disasters) that are often investigated in studies of resilience certainly are. Understanding how some individuals, perhaps because of their genetic makeup, are able to withstand such adversities can inform prevention and intervention efforts to improve mental health. PMID:23062298

Kim-Cohen, Julia; Turkewitz, Rebecca

2012-11-01

40

An automated cross-correlation based event detection technique and its application to surface passive data set  

USGS Publications Warehouse

In studies on heavy oil, shale reservoirs, tight gas and enhanced geothermal systems, the use of surface passive seismic data to monitor induced microseismicity due to the fluid flow in the subsurface is becoming more common. However, in most studies passive seismic records contain days and months of data and manually analysing the data can be expensive and inaccurate. Moreover, in the presence of noise, detecting the arrival of weak microseismic events becomes challenging. Hence, the use of an automated, accurate and computationally fast technique for event detection in passive seismic data is essential. The conventional automatic event identification algorithm computes a running-window energy ratio of the short-term average to the long-term average of the passive seismic data for each trace. We show that for the common case of a low signal-to-noise ratio in surface passive records, the conventional method is not sufficiently effective at event identification. Here, we extend the conventional algorithm by introducing a technique that is based on the cross-correlation of the energy ratios computed by the conventional method. With our technique we can measure the similarities amongst the computed energy ratios at different traces. Our approach is successful at improving the detectability of events with a low signal-to-noise ratio that are not detectable with the conventional algorithm. Also, our algorithm has the advantage to identify if an event is common to all stations (a regional event) or to a limited number of stations (a local event). We provide examples of applying our technique to synthetic data and a field surface passive data set recorded at a geothermal site.

Forghani-Arani, Farnoush; Behura, Jyoti; Haines, Seth S.; Batzle, Mike

2013-01-01

41

Gene-environment contributions to young adult sexual partnering.  

PubMed

To date, there has been relatively little work on gene-environment contributions to human sexuality, especially molecular analyses examining the potential contributions of specific polymorphisms in conjunction with life experiences. Using Wave III data from 717 heterozygous young adult sibling pairs included in the National Longitudinal Study of Adolescent Health, this article examined the combined contributions of attendance at religious services and three genetic polymorphisms (in the dopamine D4 receptor [DRD4]), dopamine D2 receptor [DRD2]), and the serotonin transporter promoter [5HTT]) to sensation seeking, a personality construct related to sexual behavior, and the number of vaginal sex partners participants had in the year before interview. Data analyses used an Allison mixed model approach to account for population stratification and correlated observations. DRD4 was unrelated to sensation seeking and to the number of sex partners in tests of both main effects and in interaction with religious attendance. Contrary to hypothesis, presence of the A1 DRD2 allele was associated with having had fewer sex partners in the past year. Associations between the 5HTT allele and sex partners varied by religious attendance, but again the patterns of associations were contrary to hypothesized relationships and were small in magnitude. These findings underscore the necessity of using more comprehensive multiple gene-multiple life experience approaches to investigations of complex behaviors such as sexual patterns. PMID:17186131

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

2007-08-01

42

Mechanomyogram amplitude correlates with human gastrocnemius medialis muscle and tendon stiffness both before and after acute passive stretching.  

PubMed

The study aimed to assess the level of correlation between muscle-tendon unit (MTU) stiffness and mechanomyogram (MMG) signal amplitude of the human gastrocnemius medialis muscle, both before and after acute passive stretching. The passive torque (Tpass), electrically evoked peak torque (pT) and myotendinous junction displacement were determined at different angles of dorsiflexion (0, 10 and 20 deg), while maximum voluntary isometric torque (Tmax) was assessed only at 0 deg. Measurements were repeated after a bout of passive stretching. From the MMG signal, the root mean square (RMS) and peak to peak (p-p) were calculated. The MTU, muscle and tendon stiffness were determined by ultrasound and Tpass measurements. Before stretching, correlations between MMG RMS and MTU, muscle and tendon stiffness were found (R(2) = 0.22-0.46). After stretching, Tpass, Tmax, pT and MTU, muscle and tendon stiffness decreased by 25 ± 7, 16 ± 2, 9 ± 2, 22 ± 7, 23 ± 8 and 28 ± 5%, respectively (P < 0.05). During voluntary and electrically evoked contractions, MMG p-p decreased by 9 ± 2 and 5 ± 1%, while MMG RMS increased by 48 ± 7 and 50 ± 8%, respectively (P < 0.05). Correlations between MMG RMS and MTU, muscle and tendon stiffness were still present after stretching (R(2) = 0.44-0.60). In conclusion, correlations between MMG RMS and stiffness exist both before and after stretching, suggesting that a slacker MTU leads to larger muscle fibre oscillations. However, care must be taken in using MMG amplitude as an indirect index to estimate stiffness owing to the relatively small R(2) values of the investigated correlations. PMID:24951499

Longo, Stefano; Cè, Emiliano; Rampichini, Susanna; Devoto, Michela; Limonta, Eloisa; Esposito, Fabio

2014-10-01

43

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

44

Information-Theoretic Metrics for Visualizing Gene-Environment Interactions  

PubMed Central

The purpose of our work was to develop heuristics for visualizing and interpreting gene-environment interactions (GEIs) and to assess the dependence of candidate visualization metrics on biological and study-design factors. Two information-theoretic metrics, the k-way interaction information (KWII) and the total correlation information (TCI), were investigated. The effectiveness of the KWII and TCI to detect GEIs in a diverse range of simulated data sets and a Crohn disease data set was assessed. The sensitivity of the KWII and TCI spectra to biological and study-design variables was determined. Head-to-head comparisons with the relevance-chain, multifactor dimensionality reduction, and the pedigree disequilibrium test (PDT) methods were obtained. The KWII and TCI spectra, which are graphical summaries of the KWII and TCI for each subset of environmental and genotype variables, were found to detect each known GEI in the simulated data sets. The patterns in the KWII and TCI spectra were informative for factors such as case-control misassignment, locus heterogeneity, allele frequencies, and linkage disequilibrium. The KWII and TCI spectra were found to have excellent sensitivity for identifying the key disease-associated genetic variations in the Crohn disease data set. In head-to-head comparisons with the relevance-chain, multifactor dimensionality reduction, and PDT methods, the results from visual interpretation of the KWII and TCI spectra performed satisfactorily. The KWII and TCI are promising metrics for visualizing GEIs. They are capable of detecting interactions among numerous single-nucleotide polymorphisms and environmental variables for a diverse range of GEI models. PMID:17924337

Chanda, Pritam ; Zhang, Aidong ; Brazeau, Daniel ; Sucheston, Lara ; Freudenheim, Jo L. ; Ambrosone, Christine ; Ramanathan, Murali 

2007-01-01

45

The nature of nurture: disentangling passive genotype-environment correlation from family relationship influences on children's externalizing problems.  

PubMed

The relationship between interparental conflict, hostile parenting, and children's externalizing problems is well established. Few studies, however, have examined the pattern of association underlying this constellation of family and child level variables while controlling for the possible confounding presence of passive genotype-environment correlation. Using the attributes of 2 genetically sensitive research designs, the present study examined associations among interparental conflict, parent-to-child hostility, and children's externalizing problems among genetically related and genetically unrelated mother-child and father-child groupings. Analyses were conducted separately by parent gender, thereby allowing examination of the relative role of the mother-child and father-child relationships on children's behavioral outcomes. Path analyses revealed that for both genetically related and genetically unrelated parents and children, indirect associations were apparent from interparental conflict to child externalizing problems through mother-to-child and father-to-child hostility. Associations between interparental conflict and parent-to-child hostility across genetically related and genetically unrelated parent-child groupings were significantly stronger for fathers compared to mothers. Results are discussed with respect to the role of passive genotype-environment correlation as a possible confounding influence in interpreting research findings from previous studies conducted in this area. Implications for intervention programs focusing on family process influences on child externalizing problems are also considered. PMID:23421830

Harold, Gordon T; Leve, Leslie D; Elam, Kit K; Thapar, Anita; Neiderhiser, Jenae M; Natsuaki, Misaki N; Shaw, Daniel S; Reiss, David

2013-02-01

46

The binding of phosphonic acids at aluminium oxide surfaces and correlation with passivation of aluminium flake.  

PubMed

Measurements of adsorption isotherms of a series of thirteen mono- and di-phosphonic acids have shown that these bind strongly to the surface of high surface area aluminium trihydroxide. The incorporation of such phosphonates into a suspension of aluminium flake in an aqueous medium, modelling the continuous phase of a water-based paint, greatly suppresses the evolution of hydrogen. Whilst strong binding of the phosphonate to aluminium oxides is an essential criterion for good passivation, other factors such as the hydrophobicity of the ligand are also important in suppressing hydrogen-evolution. PMID:17372645

Cooper, Rachel J; Camp, Philip J; Henderson, David K; Lovatt, Paul A; Nation, David A; Richards, Stuart; Tasker, Peter A

2007-04-01

47

Correlation between electronic and corrosion properties of the passive oxide film on nitinol.  

PubMed

The oxide film (TiO(2)) was formed on Nitinol potentiostatically in an acetic acid solution. Deep understanding of electronic properties of this film is needed to predict long-term corrosion properties of Nitinol implant material in simulated body fluid conditions. The capacitance measurements were performed under depletion conditions to study electronic (semiconducting) properties. The space charge, formed at the solid|liquid interface, creates the barrier for the corrosion processes in aggressive (bio)environment. According to the results of electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis (MS), the passive film on Nitinol behaves as amorphous highly-doped n-type semiconductor. The values of electronic structure parameters (the flat-band potential, E(fb) and the carrier (donor) density, N(D)) were corrected for frequency dispersion. PMID:25125118

Kati?, Jozefina; Metikoš-Hukovi?, Mirjana

2014-01-01

48

Coherent averaging of the passive fathometer response using short correlation time  

E-print Network

experimental data.1­3,8,9 The technique relies on surface generated noise from wind and waves.10,11 Ship- ping s and, for correlation times less than a few seconds, the observed sig- nal-to-noise ratio (SNR) agrees-correlation of ambient noise data from a drifting vertical array, has been the subject of much discussion in recent years

Gerstoft, Peter

49

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

PubMed

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

Takushima, Y; Chung, Y C

2007-04-30

50

Understanding risk for psychopathology through imaging gene-environment interactions  

PubMed Central

Examining the interplay of genes, experience, and the brain is critical to understanding psychopathology. We review the recent gene-environment interaction (GxE) and imaging genetics literature with the goal of developing models to bridge these approaches within single imaging gene-environment interaction (IGxE) studies. We explore challenges inherent in both GxE and imaging genetics and highlight studies that address these limitations. In specifying IGxE models, we examine statistical methods for combining these approaches, and explore plausible biological mechanisms (e.g., epigenetics) through which these conditional mechanisms can be understood. Finally, we discuss the potential contribution that IGxE studies can make to understanding psychopathology and developing more personalized and effective prevention and treatment. PMID:21839667

Hyde, Luke W.; Bogdan, Ryan; Hariri, Ahmad R.

2011-01-01

51

Calibration of Passive Microwave Polarimeters that Use Hybrid Coupler-Based Correlators  

NASA Technical Reports Server (NTRS)

Four calibration algorithms are studied for microwave polarimeters that use hybrid coupler-based correlators: 1) conventional two-look of hot and cold sources, 2) three looks of hot and cold source combinations, 3) two-look with correlated source, and 4) four-look combining methods 2 and 3. The systematic errors are found to depend on the polarimeter component parameters and accuracy of calibration noise temperatures. A case study radiometer in four different remote sensing scenarios was considered in light of these results. Applications for Ocean surface salinity, Ocean surface winds, and soil moisture were found to be sensitive to different systematic errors. Finally, a standard uncertainty analysis was performed on the four-look calibration algorithm, which was found to be most sensitive to the correlated calibration source.

Piepmeier, J. R.

2003-01-01

52

Parental punitive discipline, negative life events and gene-environment interplay in the development of externalizing behavior  

PubMed Central

Background To investigate the extent to which three putative “environmental” risk factors, maternal and paternal punitive discipline and negative life events, share genetic influences with, and moderate the heritability of, externalizing behavior. Methods The sample consisted of 2647 participants, aged 12–19 years, from the G1219 and G1219Twins longitudinal studies. Externalizing behavior was measured using the Youth Self-Report, maternal punitive discipline (MPD), paternal punitive discipline (PPD) and exposure to negative life events (NLE) were assessed using the Negative Sanctions Scale and the Life Event Scale for Adolescents respectively. Results Genetic influences overlapped for externalizing behavior and each “environmental” risk, indicating gene-environment correlation. When controlling for the gene-environment correlation genetic variance decreased, and both shared and non-shared environmental influences increased, as a function of MPD. Genetic variance increased as a function of PPD, and for NLE the only interaction effect was on the level of non-shared environment influence unique to externalizing behavior. Conclusions The magnitude of the influence of genetic risk on externalizing behavior is contextually dependent, even after controlling for gene-environment correlation. PMID:17803832

Button, Tanya M. M.; Lau, Jennifer Y.F.; Maughan, Barbara; Eley, Thalia

2010-01-01

53

Gene–Environment Interactions in Severe Mental Illness  

PubMed Central

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

Uher, Rudolf

2014-01-01

54

Mouse models of gene-environment interactions in schizophrenia  

PubMed Central

Gene-environment interactions (GEI) likely play significant roles in the pathogenesis of schizophrenia and underlie differences in pathological, behavioral, and clinical presentations of the disease. Findings from epidemiology and psychiatric genetics have assisted in the generation of animal models of GEI relevant to schizophrenia. These models may provide a foundation for elucidating the molecular, cellular, and circuitry mechanisms that mediate GEI in schizophrenia. Here we critically review current mouse models of GEI related to schizophrenia, describe directions for their improvement, and propose endophenotypes provide a more tangible basis for molecular studies of pathways of GEI and facilitate the identification of novel therapeutic targets. PMID:23748077

Kannan, Geetha; Sawa, Akira; Pletnikov, Mikhail V.

2013-01-01

55

Confluence of genes, environment, development, and behavior in a post Genome-Wide Association Study world.  

PubMed

This article serves to outline a research paradigm to investigate main effects and interactions of genes, environment, and development on behavior and psychiatric illness. We provide a historical context for candidate gene studies and genome-wide association studies, including benefits, limitations, and expected payoffs. Using substance use and abuse as our driving example, we then turn to the importance of etiological psychological theory in guiding genetic, environmental, and developmental research, as well as the utility of refined phenotypic measures, such as endophenotypes, in the pursuit of etiological understanding and focused tests of genetic and environmental associations. Phenotypic measurement has received considerable attention in the history of psychology and is informed by psychometrics, whereas the environment remains relatively poorly measured and is often confounded with genetic effects (i.e., gene-environment correlation). Genetically informed designs, which are no longer limited to twin and adoption studies thanks to ever-cheaper genotyping, are required to understand environmental influences. Finally, we outline the vast amount of individual difference in structural genomic variation, most of which remains to be leveraged in genetic association tests. Although the genetic data can be massive and burdensome (tens of millions of variants per person), we argue that improved understanding of genomic structure and function will provide investigators with new tools to test specific a priori hypotheses derived from etiological psychological theory, much like current candidate gene research but with less confusion and more payoff than candidate gene research has to date. PMID:23062291

Vrieze, Scott I; Iacono, William G; McGue, Matt

2012-11-01

56

The epigenetic lorax: gene–environment interactions in human health  

PubMed Central

Over the last decade, we have witnessed an explosion of information on genetic factors underlying common human diseases and disorders. This ‘human genomics’ information revolution has occurred as a backdrop to a rapid increase in the rates of many human disorders and diseases. For example, obesity, Type 2 diabetes, asthma, autism spectrum disorder and attention deficit hyperactivity disorder have increased at rates that cannot be due to changes in the genetic structure of the population, and are difficult to ascribe to changes in diagnostic criteria or ascertainment. A likely cause of the increased incidence of these disorders is increased exposure to environmental factors that modify gene function. Many environmental factors that have epidemiological association with common human disorders are likely to exert their effects through epigenetic alterations. This general mechanism of gene–environment interaction poses special challenges for individuals, educators, scientists and public policy makers in defining, monitoring and mitigating exposures. PMID:22920179

Latham, Keith E; Sapienza, Carmen; Engel, Nora

2012-01-01

57

Gene-environment interaction in posttraumatic stress disorder  

PubMed Central

The purpose of this article is to encourage research investigating the role of measured gene-environment interaction (G × E) in the etiology of posttraumatic stress disorder (PTSD). PTSD is uniquely suited to the study of G × E as the diagnosis requires exposure to a potentially-traumatic life event. PTSD is also moderately heritable; however, the role of genetic factors in PTSD etiology has been largely neglected both by trauma researchers and psychiatric geneticists. First, we summarize evidence for genetic influences on PTSD from family, twin, and molecular genetic studies. Second, we discuss the key challenges in G × E studies of PTSD and offer practical strategies for addressing these challenges and for discovering replicable G × E for PTSD. Finally, we propose some promising new directions for PTSD G × E research. We suggest that G × E research in PTSD is essential to understanding vulnerability and resilience following exposure to a traumatic event. PMID:18297420

Nugent, Nicole R.; Amstadter, Ananda B.

2009-01-01

58

Gene-Environment Interplay and Psychopathology: Multiple Varieties but Real Effects  

ERIC Educational Resources Information Center

Gene-environment interplay is a general term that covers several divergent concepts with different meanings and different implications. In this review, we evaluate research evidence on four varieties of gene-environment interplay. First, we consider epigenetic mechanisms by which environmental influences alter the effects of genes. Second, we…

Rutter, Michael; Moffitt, Terrie E.; Caspi, Avshalom

2006-01-01

59

Gene × environment vulnerability factors for PTSD: the HPA-axis.  

PubMed

Post-traumatic stress disorder (PTSD) is a severely debilitating psychiatric condition. Although a lifetime trauma incidence of 40-90% has been reported in the general population, the overall lifetime prevalence for PTSD ranges between 7-12%, suggesting individual-specific differences towards the susceptibility to PTSD. While studies investigating main genetic effects associated with PTSD have yielded inconsistent findings, there is growing evidence supporting the role of gene-environment (G × E) interactions in PTSD. The hypothalamus pituitary adrenal (HPA) axis is one of the main systems activated after exposure to a trauma and perturbations in this system are one of the more consistent neurobiological abnormalities observed in PTSD. Genes regulating the HPA-axis are therefore interesting candidates for G × E studies in PTSD. This article will review the concept and initial results of G × E interactions with polymorphisms in these genes for PTSD. In addition, the use of alternate phenotypes and more complex interaction models such as G × G × E or G × E × E will be explored. Finally, putative molecular mechanisms for these interactions will be presented. The research presented in this article indicates that a combined analysis of environmental, genetic, endophenotype and epigenetic data will be necessary to better understand pathomechanisms in PTSD. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'. PMID:21439305

Mehta, Divya; Binder, Elisabeth B

2012-02-01

60

Gene-environment interactions in the etiology of human violence.  

PubMed

This chapter reviews the current research on gene-environment interactions (G × E) with regard to human violence. Findings are summarized from both behavioral and molecular genetic studies that have investigated the interplay of genetic and environmental factors in terms of influencing violence-related behavior. Together, these studies reveal promising evidence that genetic factors combine with environmental influences to impact on the development of violent behavior and related phenotypes. G × E have been identified for a number of candidate genes implicated in violence. Moreover, the reviewed G × E were found to extend to a broad range of environmental characteristics, including both adverse and favorable conditions. As has been the case with other G × E research, findings have been mixed, with considerable heterogeneity between studies. Lack of replication together with serious methodological limitations remains a major challenge for drawing definitive conclusions about the nature of violence-related G × E. In order to fulfill its potential, it is recommended that future G × E research needs to shift its focus to dissecting the neural mechanisms and the underlying pathophysiological pathways by which genetic variation may influence differential susceptibility to environmental exposures. PMID:24362945

Laucht, Manfred; Brandeis, Daniel; Zohsel, Katrin

2014-01-01

61

Sleep Duration and Depressive Symptoms: A Gene-Environment Interaction  

PubMed Central

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

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

2014-01-01

62

Electrophysiological Correlates of the Threshold to Detection of Passive Motion: An Investigation in Professional Volleyball Athletes with and without Atrophy of the Infraspinatus Muscle  

PubMed Central

The goal of the present study is to compare the electrophysiological correlates of the threshold to detection of passive motion (TTDPM) among three groups: healthy individuals (control group), professional volleyball athletes with atrophy of the infraspinatus muscle on the dominant side, and athletes with no shoulder pathologies. More specifically, the study aims at assessing the effects of infraspinatus muscle atrophy on the cortical representation of the TTDPM. A proprioception testing device (PTD) was used to measure the TTDPM. The device passively moved the shoulder and participants were instructed to respond as soon as movement was detected (TTDPM) by pressing a button switch. Response latency was established as the delay between the stimulus (movement) and the response (button press). Electroencephalographic (EEG) and electromyographic (EMG) activities were recorded simultaneously. An analysis of variance (ANOVA) and subsequent post hoc tests indicated a significant difference in latency between the group of athletes without the atrophy when compared both to the group of athletes with the atrophy and to the control group. Furthermore, distinct patterns of cortical activity were observed in the three experimental groups. The results suggest that systematically trained motor abilities, as well as the atrophy of the infraspinatus muscle, change the cortical representation of the different stages of proprioceptive information processing and, ultimately, the cortical representation of the TTDPM. PMID:23484136

Salles, José Inácio; Cossich, Victor Rodrigues Amaral; Amaral, Marcus Vinicius; Monteiro, Martim T.; Cagy, Maurício; Motta, Geraldo; Velasques, Bruna; Piedade, Roberto; Ribeiro, Pedro

2013-01-01

63

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

PubMed Central

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 gene-environment interactions are now fairly common in human genetic research, and with the shift towards genome-wide association studies, genome-wide gene-environment interaction studies are beginning to emerge. Methods We summarize the basic ideas behind gene-environment interaction, and provide an overview of possible study designs and traditional analysis methods in the context of genome-wide analysis. We then discuss novel approaches beyond the traditional strategy of analyzing the interaction between the environmental factor and each polymorphism individually. Results Two-step filtering approaches that reduce the number of polymorphisms tested for interactions can substantially increase the power of genome-wide gene-environment studies. New analytical methods including data-mining approaches, and gene-level and pathway-level analyses, also have the capacity to improve our understanding of how complex genetic and environmental factors interact to influence psychological and psychiatric traits. Such methods, however, have not yet been utilized much in behavioral and mental health research. Conclusions Although methods to investigate gene-environment interactions are available, there is a need for further development and extension of these methods to identify gene-environment interactions in the context of genome-wide association studies. These novel approaches need to be applied in studies of psychology and psychiatry. PMID:23808649

Winham, Stacey J; Biernacka, Joanna M.

2013-01-01

64

Immune correlates of protection against yellow fever determined by passive immunization and challenge in the hamster model  

PubMed Central

Live, attenuated yellow fever (YF) 17D vaccine is highly efficacious but causes rare, serious adverse events resulting from active replication in the host and direct viral injury to vital organs. We recently reported development of a potentially safer ?-propiolactone-inactivated whole virion YF vaccine (XRX-001) which was highly immunogenic in mice, hamsters, monkeys, and humans (Vaccine 2010; 28:3827–40; New Engl J Med 2011;364:1326–33). To characterize the protective efficacy of neutralizing antibodies stimulated by the inactivated vaccine, graded doses of serum from hamsters immunized with inactivated XRX-001 or live 17D vaccine were transferred to hamsters by the intraperitoneal (IP) route 24 hours prior to virulent, viscerotropic YF virus challenge. Neutralizing antibody (PRNT50) titers were determined in the sera of treated animals 4 hours before challenge and 4 and 21 days after challenge. Neutralizing antibodies were shown to mediate protection. Animals having 50% plaque reduction neutralization test (PRNT50) titers of ?40 four hours before challenge were completely protected from disease as evidenced by viremia, liver enzyme elevation, and protection against illness (weight change) and death. Passive titers of 10–20 were partially protective. Immunization with the XRX-001 vaccine stimulated YF neutralizing antibodies that were equally effective (based on dose response) as antibodies stimulated by live 17D vaccine. The results will be useful in defining the level of seroprotection in clinical studies of new yellow fever vaccines. PMID:21718741

Julander, Justin G.; Trent, Dennis W.; Monath, Thomas P.

2011-01-01

65

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

ERIC Educational Resources Information Center

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…

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

2012-01-01

66

Gene-environment interactions and obesity: recent developments and future directions  

PubMed Central

Obesity, a major public health concern, is a multifactorial disease caused by both environmental and genetic factors. Although recent genome-wide association studies have identified many loci related to obesity or body mass index, the identified variants explain only a small proportion of the heritability of obesity. Better understanding of the interplay between genetic and environmental factors is the basis for developing effective personalized obesity prevention and management strategies. This article reviews recent advances in identifying gene-environment interactions related to obesity and describes epidemiological designs and newly developed statistical approaches to characterizing and discovering gene-environment interactions on obesity risk.

2015-01-01

67

Commentary: Gene-Environment Interplay in the Context of Genetics, Epigenetics, and Gene Expression.  

ERIC Educational Resources Information Center

Objective: To comment on the article in this issue of the Journal by Professor Michael Rutter, "Environmentally Mediated Risks for Psychopathology: Research Strategies and Findings," in the context of current research findings on gene-environment interaction, epigenetics, and gene expression. Method: Animal and human studies are reviewed that…

Kramer, Douglas A.

2005-01-01

68

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

ERIC Educational Resources Information Center

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…

Winham, Stacey J.; Biernacka, Joanna M.

2013-01-01

69

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

E-print Network

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

Paris-Sud XI, Université de

70

Gene-Environment Interplay in Internalizing Disorders: Consistent Findings across Six Environmental Risk Factors  

ERIC Educational Resources Information Center

Background: Behavior genetic methods can help to elucidate gene-environment (G-E) interplay in the development of internalizing (INT) disorders (i.e., major depression and anxiety disorders). To date, however, no study has conducted a comprehensive analysis examining multiple environmental risk factors with the purpose of delineating general…

Hicks, Brian M.; Dirago, Ana C.; Iacono, William G.; McGue, Matt

2009-01-01

71

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

Microsoft Academic Search

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

FARID E. AHMED

2006-01-01

72

Multifactor dimensionality reduction software for detecting gene-gene and gene-environment interactions  

Microsoft Academic Search

Motivation: Polymorphisms in human genes are being described in remarkable numbers. Determining which polymorphisms and which environmental factors are associated with common, complex diseases has become a daunting task. This is partly because the effect of any single genetic variation will likely be dependent on other genetic variations (gene-gene interaction or epistasis) and environmental factors (gene-environment interac- tion). Detecting and

Lance W. Hahn; Marylyn D. Ritchie; Jason H. Moore

2003-01-01

73

Mechanisms of Gene Environment Interaction Effects in the Development of Conduct Disorder  

Microsoft Academic Search

ABSTRACT? The gene? environment,interaction effect in the development,of conduct disorder is one of the most important discoveries of the past decade, but the mechanisms through which this effect operates remain elusive. I propose a model of these processes that focuses on the individual? s response to a threatening stimulus in ongoing social interaction. The individual? s response coordinates three interrelated

Kenneth A. Dodge

2009-01-01

74

Composite thin films of CdSe nanocrystals and a surface passivating/electron transporting block copolymer: Correlations between film microstructure by transmission electron microscopy and electroluminescence  

NASA Astrophysics Data System (ADS)

We present a microscopic characterization of composite thin films made of CdSe semiconductor nanocrystals (quantum dots) dispersed in a polynorbornene-based block copolymer with surface-passivating and electron transport functionalities. We used two types of nanocrystals, CdSe with pure organic capping groups ("bare") and CdSe-ZnS core-shell nanocrystals, also capped on the outer surface with organic groups. The composite thin films are incorporated in heterostructure light emitting devices where they serve as both the electron transport layer and the emissive layer. A thin layer of self-assembled poly (phenylene vinylene) (PPV) is used as the hole transport layer. We used transmission electron microscopy (TEM) to examine the film structure in plan view and in cross section. The TEM analysis uncovered distinct and complex differences between the microstructures of thin films containing bare and ZnS overcoated nanocrystals. We found a strong correlation between the composite film microstructure and the corresponding electroluminescence (EL) spectra as well as the device performance. For example, the presence of phase separation at low concentration and nanocrystal migration to the surface in films with ZnS overcoated particles, result in a large PPV contribution to the EL spectra. At higher concentrations, particles form connecting paths between the interfaces, resulting in spectra dominated by nanocrystal emission, but with a higher efficiency for bare particles.

Mattoussi, H.; Radzilowski, L. H.; Dabbousi, B. O.; Fogg, D. E.; Schrock, R. R.; Thomas, E. L.; Rubner, M. F.; Bawendi, M. G.

1999-10-01

75

Correlation  

Microsoft Academic Search

Reviews 7 studies in the area of interpretation of correlation from the psychological point of view. The limitations and meanings of correlation methods have also been given. The statistical methods of calculating correlation, as given by 8 psychologists have been reported. Presents 22 reports, given by various psychologists, who have evaluated the tests using various correlation methods. Six studies were

James Burt Miner

1919-01-01

76

Correlation  

NSDL National Science Digital Library

This chapter will discuss the concept of correlation , which is used in later chapters that will explain the concepts of validity and reliability. Here, the authors introduce the Pearson correlation coefficient, a statistic that is used with ratio

Christmann, Edwin P.; Badgett, John L.

2008-11-01

77

Gene-Environment Interactions in Cancer Epidemiology: A National Cancer Institute Think Tank Report  

PubMed Central

Cancer risk is determined by a complex interplay of genetic and environmental factors. Genome-wide association studies (GWAS) have identified hundreds of common (minor allele frequency [MAF]>0.05) and less common (0.01gene-environment interactions, into epidemiologic studies of cancer. To help address these questions, and to better inform research priorities and allocation of resources, the National Cancer Institute sponsored a “Gene-Environment Think Tank” on January 10th–011th, 2012. The objective of the Think Tank was to facilitate discussions on: 1) the state of the science; 2) the goals of gene-environment interaction studies in cancer epidemiology; and 3) opportunities for developing novel study designs and analysis tools. This report summarizes the Think Tank discussion, with a focus on contemporary approaches to the analysis of gene-environment interactions. Selecting the appropriate methods requires first identifying the relevant scientific question and rationale, with an important distinction made between analyses aiming to characterize the joint effects of putative or established genetic and environmental factors and analyses aiming to discover novel risk factors or novel interaction effects. Other discussion items include measurement error, statistical power, significance and replication. Additional designs, exposure assessments, and analytical approaches need to be considered as we move from the current small number of success stories to a fuller understanding of the interplay of genetic and environmental factors. PMID:24123198

Hutter, Carolyn M.; Mechanic, Leah E.; Chatterjee, Nilanjan; Kraft, Peter; Gillander, Elizabeth M.

2014-01-01

78

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

PubMed Central

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

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

79

Aggressively Passive  

E-print Network

AGRESSIVELY PASSIVE DESIGNING WITH CFD ESL-KT-13-12-48 CATEE 2013: Clean Air Through Energy Efficiency Conference, San Antonio, Texas Dec. 16-18 ESL-KT-13-12-48 CATEE 2013: Clean Air Through Energy Efficiency Conference, San Antonio, Texas Dec. 16...-18 Can passive ventilation work in a hot humid climate ESL-KT-13-12-48 CATEE 2013: Clean Air Through Energy Efficiency Conference, San Antonio, Texas Dec. 16-18 ESL-KT-13-12-48 CATEE 2013: Clean Air Through Energy Efficiency Conference, San Antonio...

Upadhyaya, K.

2013-01-01

80

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

Microsoft Academic Search

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

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

2010-01-01

81

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

PubMed

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

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

2015-01-01

82

The case-only test for gene-environment interaction is not uniformly powerful: an empirical example.  

PubMed

The case-only test has been proposed as a more powerful approach to detect gene-environment (G × E) interactions. This approach assumes that the genetic and environmental factors are independent. Although it is well known that Type I error rate will increase if this assumption is violated, it is less widely appreciated that G × E correlation can also lead to power loss. We illustrate this phenomenon by comparing the performance of the case-only test to other approaches to detect G × E interactions in a genome-wide association study (GWAS) of esophageal squamous-cell carcinoma (ESCC) in Chinese populations. Some of these approaches do not use information on the correlation between exposure and genotype (standard logistic regression), whereas others seek to use this information in a robust fashion to boost power without increasing Type I error (two-step, empirical Bayes, and cocktail methods). G × E interactions were identified involving drinking status and two regions containing genes in the alcohol metabolism pathway, 4q23 and 12q24. Although the case-only test yielded the most significant tests of G × E interaction in the 4q23 region, the case-only test failed to identify significant interactions in the 12q24 region which were readily identified using other approaches. The low power of the case-only test in the 12q24 region is likely due to the strong inverse association between the single nucleotide polymorphism (SNPs) in this region and drinking status. This example underscores the need to consider multiple approaches to detect G × E interactions, as different tests are more or less sensitive to different alternative hypotheses and violations of the G × E independence assumption. PMID:23595356

Wu, Chen; Chang, Jiang; Ma, Baoshan; Miao, Xiaoping; Zhou, Yifeng; Liu, Yu; Li, Yun; Wu, Tangchun; Hu, Zhibin; Shen, Hongbing; Jia, Weihua; Zeng, Yixin; Lin, Dongxin; Kraft, Peter

2013-05-01

83

Genetic Risk for Schizophrenia, Obstetric Complications, and Adolescent School Outcome: Evidence for Gene-Environment Interaction  

PubMed Central

Low birth weight (LBW) and hypoxia are among the environmental factors most reliably associated with schizophrenia; however, the nature of this relationship is unclear and both gene-environment interaction and gene-environment covariation models have been proposed as explanations. High-risk (HR) designs that explore whether obstetric complications differentially predict outcomes in offspring at low risk (LR) vs HR for schizophrenia, while accounting for differences in rates of maternal risk factors, may shed light on this question. This study used prospectively obtained data to examine relationships between LBW and hypoxia on school outcome at age 15–16 years in a Finnish sample of 1070 offspring at LR for schizophrenia and 373 offspring at HR for schizophrenia, based on parental psychiatric history. Controlling for offspring sex, maternal smoking, social support, parity, age, and number of prenatal care visits, HR offspring performed worse than LR offspring across academic, nonacademic, and physical education domains. LBW predicted poorer academic and physical education performance in HR offspring, but not in LR offspring, and this association was similar for offspring of fathers vs mothers with schizophrenia. Hypoxia predicted poorer physical education score across risk groups. Rates of LBW and hypoxia were similar for LR and HR offspring and for offspring of fathers vs mothers with schizophrenia. Results support the hypothesis that genetic susceptibility to schizophrenia confers augmented vulnerability of the developing brain to the effects of obstetric complications, possibly via epigenetic mechanisms. PMID:22941745

Cannon, Tyrone D.

2013-01-01

84

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

PubMed Central

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

2013-01-01

85

Correlation  

NSDL National Science Digital Library

Three hypothetical rock sections along an East-West transect are provided. Students correlate the three sections using the biostratigraphy of planktic forams (as a proxy for age), benthic forams (as a proxy of depth), and lithology (as a proxy of environment). Students are asked to provide an interpretation of the history of this depositional basin. An ash bed of known age is added and students are asked to determine if this new information affects their interpretation. Finally, an interesting lithologic feature is added, and students are asked to provide a geological explanation.

Pennilyn Higgins

86

Defining the Environment in Gene–Environment Research: Lessons From Social Epidemiology  

PubMed Central

In this article, we make the case that social epidemiology provides a useful framework to define the environment within gene–environment (G×E) research. We describe the environment in a multilevel, multidomain, longitudinal framework that accounts for upstream processes influencing health outcomes. We then illustrate the utility of this approach by describing how intermediate levels of social organization, such as neighborhoods or schools, are key environmental components of G×E research. We discuss different models of G×E research and encourage public health researchers to consider the value of including genetic information from their study participants. We also encourage researchers interested in G×E interplay to consider the merits of the social epidemiology model when defining the environment. PMID:23927514

Daw, Jonathan; Freese, Jeremy

2013-01-01

87

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

PubMed Central

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

Samek, Diana R.; Hicks, Brian M.

2014-01-01

88

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

PubMed

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

Samek, Diana R; Hicks, Brian M

2014-01-01

89

Development and the epigenome: the 'synapse' of gene-environment interplay.  

PubMed

This paper argues that there is a revolution afoot in the developmental science of gene-environment interplay. We summarize, for an audience of developmental researchers and clinicians, how epigenetic processes - chromatin structural modifications that regulate gene expression without changing DNA sequences - may offer a strong, parsimonious account for the convergence of genetic and contextual variation in the genesis of adaptive and maladaptive development. Epigenetic processes may play a plausible explanatory role in understanding: divergent trajectories and sexual dimorphisms in brain development; statistical interactions between genes and environments; the biological embedding of early psychosocial adversities; the linkages of such adversities to disorders of mental health; the striking individual variation in the strength of those linkages; the molecular origins of critical and sensitive periods; and the transgenerational inheritance of risk and protection. Taken together, these arguments converge in a claim that epigenetic processes constitute a promising and illuminating point of connection - a 'synapse' - between genes and environments. PMID:25546559

Boyce, W Thomas; Kobor, Michael S

2015-01-01

90

Gene-gene and gene-environment interactions detected by transcriptome sequence analysis in twins.  

PubMed

Understanding the genetic architecture of gene expression is an intermediate step in understanding the genetic architecture of complex diseases. RNA sequencing technologies have improved the quantification of gene expression and allow measurement of allele-specific expression (ASE). ASE is hypothesized to result from the direct effect of cis regulatory variants, but a proper estimation of the causes of ASE has not been performed thus far. In this study, we take advantage of a sample of twins to measure the relative contributions of genetic and environmental effects to ASE, and we find substantial effects from gene × gene (G×G) and gene × environment (G×E) interactions. We propose a model where ASE requires genetic variability in cis, a difference in the sequence of both alleles, but where the magnitude of the ASE effect depends on trans genetic and environmental factors that interact with the cis genetic variants. PMID:25436857

Buil, Alfonso; Brown, Andrew Anand; Lappalainen, Tuuli; Viñuela, Ana; Davies, Matthew N; Zheng, Hou-Feng; Richards, J Brent; Glass, Daniel; Small, Kerrin S; Durbin, Richard; Spector, Timothy D; Dermitzakis, Emmanouil T

2015-01-01

91

Mechanisms of Gene–Environment Interaction Effects in the Development of Conduct Disorder  

PubMed Central

The gene–environment interaction effect in the development of conduct disorder is one of the most important discoveries of the past decade, but the mechanisms through which this effect operates remain elusive. I propose a model of these processes that focuses on the individual’s response to a threatening stimulus in ongoing social interaction. The individual’s response coordinates three interrelated systems: neural, autonomic, and information-processing. In each system, adaptive, evolutionarily selected response patterns characterize normal responding, but in psychopathology these patterns have gone awry. Antecedents of individual differences in these response patterns arise from genetic polymorphisms, adverse environmental experiences early in life, and their interaction. Programs of research are proposed to test hypotheses in the model through longitudinal, experimental, and clinical intervention methods. This model can serve as a template for inquiry in other forms of developmental psychopathology. PMID:19779577

Dodge, Kenneth A.

2009-01-01

92

Defining the environment in gene-environment research: lessons from social epidemiology.  

PubMed

In this article, we make the case that social epidemiology provides a useful framework to define the environment within gene-environment (G × E) research. We describe the environment in a multilevel, multidomain, longitudinal framework that accounts for upstream processes influencing health outcomes. We then illustrate the utility of this approach by describing how intermediate levels of social organization, such as neighborhoods or schools, are key environmental components of G × E research. We discuss different models of G × E research and encourage public health researchers to consider the value of including genetic information from their study participants. We also encourage researchers interested in G × E interplay to consider the merits of the social epidemiology model when defining the environment. PMID:23927514

Boardman, Jason D; Daw, Jonathan; Freese, Jeremy

2013-10-01

93

Passive Semantics: Ambiguity of the Short Passive.  

ERIC Educational Resources Information Center

Presents clues for determining whether "short passives," passive sentences from which the "by"-phrase has been deleted, are actually passive or stative. The clues include intensifiers, the verb "seems," contrasts, present tense, past tense, progressive aspect, and confirmation by examples. (CB)

Cook, Walter A.

1990-01-01

94

Research Review: Gene-Environment Interaction Research in Youth Depression--A Systematic Review with Recommendations for Future Research  

ERIC Educational Resources Information Center

Background: Depression is a major public health problem among youth, currently estimated to affect as many as 9% of US children and adolescents. The recognition that both genes (nature) and environments (nurture) are important for understanding the etiology of depression has led to a rapid growth in research exploring gene-environment interactions…

Dunn, Erin C.; Uddin, Monica; Subramanian, S. V.; Smoller, Jordan W.; Galea, Sandro; Koenen, Karestan C.

2011-01-01

95

Testing gene-environment interactions in family-based association studies using trait-based ascertained samples  

PubMed Central

The study of gene-environment interactions is an increasingly important aspect of genetic epidemiological investigation. Historically, it has been difficult to study gene-environment interactions using a family-based design for quantitative traits or when parent-offspring trios were incomplete. The QBAT-I[1] provides researchers a tool to estimate and test for a gene-environment interaction in families of arbitrary structure that are sampled without regard to the phenotype of interest, but is vulnerable to inflated type I error if families are ascertained based on the phenotype. In this study, we verified the potential for type I error of the QBAT-I when applied to samples ascertained on a trait of interest. The magnitude of the inflation increases as the main genetic effect increases and as the ascertainment becomes more extreme. We propose an ascertainment-corrected score test that allows use of the QBAT-I to test for gene-environment interactions in ascertained samples. Our results indicate that the score test and an ad-hoc method we propose can often restore the nominal type I error rate, and in cases where complete restoration is not possible, dramatically reduce the inflation of the type I error rate in ascertained samples. PMID:23922213

Zhang, Weiming; Langefeld, Carl D.; Grunwald, Gary K.; Fingerlin, Tasha E.

2014-01-01

96

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

ERIC Educational Resources Information Center

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…

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

2009-01-01

97

All in the FamilyGene × Environment Interaction Between DRD2 and Criminal Father Is Associated With Five Antisocial Phenotypes  

Microsoft Academic Search

A range of Gene × Environment interactions is associated with antisocial phenotypes, and the evidence is clear that the etiology of antisocial behavior is strongly heritable and that environmental liabilities are important. However, the precise ways that genetic and environmental pathogens interact to predict antisocial behavior are underspecified. The present study shows that the interaction between a polymorphism in a

Matt DeLisi; Kevin M. Beaver; Michael G. Vaughn; John Paul Wright

2009-01-01

98

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

ERIC Educational Resources Information Center

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…

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

99

Discovering gene-environment interactions in glioblastoma through a comprehensive data integration bioinformatics method.  

PubMed

Glioblastoma multiforme (GBM) is the most common and aggressive type of human brain tumor. Although considerable efforts to delineate the underlying pathophysiological pathways have been made during the last decades, only very limited progress on treatment have been achieved because molecular pathways that drive the aggressive nature of GBM are largely unknown. Recent studies have emphasized the importance of environmental factors and the role of gene-environment interactions (GEI) in the development of GBM. Factors such as small sample sizes and study costs have limited the conduct of GEI studies in brain tumors however. Additionally, advances in high-throughput microarrays have produced a wealth of information concerning molecular biology of glioma. In particular, microarrays have been used to obtain genetic and epigenetic changes between normal non-tumor tissue and glioma tissue. Due to the relative rarity of gliomas, microarray data for these tumors is often the product of small studies, and thus pooling this data becomes desirable. To address the challenge of small sample sizes and GEI study difficulties, we introduce a comprehensive bioinformatics method using genetic variations (copy number variations and small-scale variations) and environmental data integration that links with glioblastoma (GEG) to identify: (1) genes that interact with chemicals and have genetic variants linked to the development of GBM, (2) important pathways that may be influenced by environmental exposures (or endogenous chemicals), and (3) genes with variants in GBM that have been understudied in relation to GBM development. The first step in our GEG method identified genes responsive to environmental exposures using the Environmental Genome Project, Comparative Toxicology, and Seattle SNPs databases. These environmentally responsive genes were then compared to a curated list of genes containing copy number variation and/or mutations in GBM. This comparison produced a list of genes responsive to the environment and important to GBM that was then further analyzed using gene networking tools such as RSpider, Cytoscape, and DAVID. Using this GEG bioinformatics method we were able to identify 173 genes with the potential to be involved in GEI that may be important to the development of GBM. Sixty five of these environmentally responsive genes have not been reported as important to GBM development, despite several of them having substantial potential for response to chemicals and subsequent disease related actions. The main biological functions of these 173 genes include signaling by nerve growth factor, DNA repair, integrin cell surface interactions, biological oxidations, apoptosis, synaptic transmission, cell cycle checkpoints, and arachidonic acid metabolism. Importantly, some of these functions have been implicated in the development of several cancers, including glioma. In summary, our GEG bioinformatics approach revealed potential gene-environment interactions, and generated new data for hypothesis generation, in GBM. PMID:23261424

Kunkle, Brian; Yoo, Changwon; Roy, Deodutta

2013-03-01

100

Genes, Environments, Personality, and Successful Aging: Toward a Comprehensive Developmental Model in Later Life  

PubMed Central

Background. Outcomes in aging and health research, such as longevity, can be conceptualized as reflecting both genetic and environmental (nongenetic) effects. Parsing genetic and environmental influences can be challenging, particularly when taking a life span perspective, but an understanding of how genetic variants and environments relate to successful aging is critical to public health and intervention efforts. Methods. We review the literature, and survey promising methods, to understand this interplay. We also propose the investigation of personality as a nexus connecting genetics, environments, and health outcomes. Results. Personality traits may reflect psychological mechanisms by which underlying etiologic (genetic and environmental) effects predispose individuals to broad propensities to engage in (un)healthy patterns of behavior across the life span. In terms of methodology, traditional behavior genetic approaches have been used profitably to understand how genetic factors and environments relate to health and personality in somewhat separate literatures; we discuss how other behavior genetic approaches can help connect these literatures and provide new insights. Conclusions. Co-twin control designs can be employed to help determine causality via a closer approximation of the idealized counterfactual design. Gene-by-environment interaction (G × E) designs can be employed to understand how individual difference characteristics, such as personality, might moderate genetic and environmental influences on successful aging outcomes. Application of such methods can clarify the interplay of genes, environments, personality, and successful aging. PMID:22454369

Krueger, Robert F.; South, Susan C.; Gruenewald, Tara L.; Seeman, Teresa E.; Roberts, Brent W.

2012-01-01

101

Gene-environment interactions in the etiology of obesity: defining the fundamentals.  

PubMed

The concept of gene-environment interaction refers to a situation where the response or the adaptation to an environmental factor, a behavior, or a change in behavior is conditional on the genotype of the individual. Of particular interest for our understanding of the etiology of human obesity is the role played by genotype-nutrition and genotype-physical activity interactions. Evidence for the presence of such interaction effects affecting body mass and body composition comes from experimental studies undertaken with pairs of monozygotic twins and with nuclear families. These studies reveal that there are large individual differences in the responsiveness to well-defined energy balance manipulations. Overfeeding as well as negative energy balance protocols indicate that the response to these standardized experimental treatments is strongly influenced by one's genetic background. The genes that are responsible for the individual differences in the sensitivity to alterations in energy balance remain to be fully identified. They are likely to be numerous considering the complexity of the biological systems that are involved in body weight regulation. A number of research designs and technologies are available to identify these genes and to delineate the nature and the extent of the genetic polymorphisms involved. It was the purpose of the workshop to define the conditions under which gene-behavior interaction effects of relevance to human obesity could be reliably identified. PMID:19037213

Bouchard, Claude

2008-12-01

102

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

PubMed Central

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

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

2008-01-01

103

Normal and abnormal cerebrovascular development: gene-environment interactions during early life with later life consequences.  

PubMed

A greater understanding of cerebrovascular health and disease requires the consideration of recent neuroscience advances concerning neuroplasticity in the context of classical developmental neurology principles. Consideration of the ontogenetic interplay of nature and nurture influencing brain development during prenatal and early postnatal time periods should consider the concept of the developmental origins of neurological health and disease. Adaptive and maladaptive effects of neuroplasticity require a systems biology approach integrating molecular, receptor, cellular, neural network, and behavioral perspectives, culminating in the structural and functional cerebrovascular phenotypes that express health or disease across the lifespan. Cognizance of the interrelationships among maternal, placental, fetal, and neonatal factors requires an interdisciplinary appreciation of genetic/epigenetic forces of neuroplasticity during early life that incrementally influence cerebrovascular health or disease throughout childhood and adulthood. Knowledge of the systemic effects of multiorgan function on cerebrovascular development further broadens the systems biology approach to general plasticity of the individual as a whole organism. Short- and long-term consequences of the positive and negative effects of neuroplasticity must consider ongoing gene-environment interactions with maturation and aging, superimposed on earlier fetal/neonatal experiences that sustain neurological health or contribute to disease during childhood and adulthood. PMID:23622309

Scher, Mark S

2013-01-01

104

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

PubMed

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

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

2015-01-01

105

Genome-wide analysis of gestational gene-environment interactions in the developing kidney.  

PubMed

The G protein-coupled bradykinin B2 receptor (Bdkrb2) plays an important role in regulation of blood pressure under conditions of excess salt intake. Our previous work has shown that Bdkrb2 also plays a developmental role since Bdkrb2(-/-) embryos, but not their wild-type or heterozygous littermates, are prone to renal dysgenesis in response to gestational high salt intake. Although impaired terminal differentiation and apoptosis are consistent findings in the Bdkrb2(-/-) mutant kidneys, the developmental pathways downstream of gene-environment interactions leading to the renal phenotype remain unknown. Here, we performed genome-wide transcriptional profiling on embryonic kidneys from salt-stressed Bdkrb2(+/+) and Bdkrb2(-/-) embryos. The results reveal significant alterations in key pathways regulating Wnt signaling, apoptosis, embryonic development, and cell-matrix interactions. In silico analysis reveal that nearly 12% of differentially regulated genes harbor one or more Pax2 DNA-binding sites in their promoter region. Further analysis shows that metanephric kidneys of salt-stressed Bdkrb2(-/-) have a significant downregulation of Pax2 gene expression. This was corroborated in Bdkrb2(-/-);Pax2(GFP+/tg) mice, demonstrating that Pax2 transcriptional activity is significantly repressed by gestational salt-Bdkrb2 interactions. We conclude that gestational gene (Bdkrb2) and environment (salt) interactions cooperate to impact gene expression programs in the developing kidney. Suppression of Pax2 likely contributes to the defects in epithelial survival, growth, and differentiation in salt-stressed BdkrB2(-/-) mice. PMID:25005792

Yan, Lei; Yao, Xiao; Bachvarov, Dimcho; Saifudeen, Zubaida; El-Dahr, Samir S

2014-09-01

106

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

PubMed Central

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

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

107

Gene × environment interaction on intergroup bias: the role of 5-HTTLPR and perceived outgroup threat.  

PubMed

Perceived threat from outgroups is a consistent social-environmental antecedent of intergroup bias (i.e. prejudice, ingroup favoritism). The serotonin transporter gene polymorphism (5-HTTLPR) has been associated with individual variations in sensitivity to context, particularly stressful and threatening situations. Here, we examined how 5-HTTLPR and environmental factors signaling potential outgroup threat dynamically interact to shape intergroup bias. Across two studies, we provide novel evidence for a gene-environment interaction on the acquisition of intergroup bias and prejudice. Greater exposure to signals of outgroup threat, such as negative prior contact with outgroups and perceived danger from the social environment, were more predictive of intergroup bias among participants possessing at least one short allele (vs two long alleles) of 5-HTTLPR. Furthermore, this gene x environment interaction was observed for biases directed at diverse ethnic and arbitrarily-defined outgroups across measures reflecting intergroup biases in evaluation and discriminatory behavior. These findings reveal a candidate genetic mechanism for the acquisition of intergroup bias, and suggest that intergroup bias is dually inherited and transmitted through the interplay of social (i.e. contextual cues of outgroup threat) and biological mechanisms (i.e. genetic sensitivity toward threatening contexts) that regulate perceived intergroup threats. PMID:23887814

Cheon, Bobby K; Livingston, Robert W; Hong, Ying-Yi; Chiao, Joan Y

2014-09-01

108

Gene-Environment Interactions of Novel Variants Associated with Head and Neck Cancer  

PubMed Central

Background A genome-wide association study for upper aerodigestive tract cancers identified 19 candidate single-nucleotide polymorphisms (SNPs). We used these SNPs to investigate the potential gene-gene and gene-environment interactions in head and neck squamous cell carcinoma (HNSCC) risk. Methods The 19 variants were genotyped using Taqman (Applied Biosystems) assays among 575 cases and 676 controls in our population-based case-control study. Results A restricted cubic spline model suggested both ADH1B and HEL308 modified the association between smoking pack-years and HNSCC. Classification and regression tree analysis demonstrated a higher order interaction between smoking status, ADH1B, FLJ13089 and FLJ35784 in HNSCC risk. Compared with ever smokers carrying ADH1B T/C+T/T genotypes, smokers carrying ADH1B C/C genotype and FLJ13089 A/G+A/A genotypes had a highest risk of HNSCC (OR=1.84). Conclusions Our results suggest that the risk associated with these variants may be specifically important amongst specific exposure groups. PMID:22052802

Liang, Caihua; Marsit, Carmen J.; Houseman, E. Andres; Butler, Rondi; Nelson, Heather H.; McClean, Michael D.; Kelsey, Karl T.

2013-01-01

109

Gene?×?Environment Interactions in Autism Spectrum Disorders: Role of Epigenetic Mechanisms  

PubMed Central

Several studies support currently the hypothesis that autism etiology is based on a polygenic and epistatic model. However, despite advances in epidemiological, molecular and clinical genetics, the genetic risk factors remain difficult to identify, with the exception of a few chromosomal disorders and several single gene disorders associated with an increased risk for autism. Furthermore, several studies suggest a role of environmental factors in autism spectrum disorders (ASD). First, arguments for a genetic contribution to autism, based on updated family and twin studies, are examined. Second, a review of possible prenatal, perinatal, and postnatal environmental risk factors for ASD are presented. Then, the hypotheses are discussed concerning the underlying mechanisms related to a role of environmental factors in the development of ASD in association with genetic factors. In particular, epigenetics as a candidate biological mechanism for gene?×?environment interactions is considered and the possible role of epigenetic mechanisms reported in genetic disorders associated with ASD is discussed. Furthermore, the example of in utero exposure to valproate provides a good illustration of epigenetic mechanisms involved in ASD and innovative therapeutic strategies. Epigenetic remodeling by environmental factors opens new perspectives for a better understanding, prevention, and early therapeutic intervention of ASD. PMID:25136320

Tordjman, Sylvie; Somogyi, Eszter; Coulon, Nathalie; Kermarrec, Solenn; Cohen, David; Bronsard, Guillaume; Bonnot, Olivier; Weismann-Arcache, Catherine; Botbol, Michel; Lauth, Bertrand; Ginchat, Vincent; Roubertoux, Pierre; Barburoth, Marianne; Kovess, Viviane; Geoffray, Marie-Maude; Xavier, Jean

2014-01-01

110

Methods for Investigating Gene-Environment Interactions in Candidate Pathway and Genome-Wide Association Studies  

PubMed Central

Despite the considerable enthusiasm about the yield of novel and replicated discoveries of genetic associations from the new generation of genome-wide association studies (GWAS), the proportion of the heritability of most complex diseases that have been studied to date remains small. Some of this “dark matter” could be due to gene-environment (G×E) interactions or more complex pathways involving multiple genes and exposures. We review the basic epidemiologic study design and statistical analysis approaches to studying G×E interactions individually and then consider more comprehensive approaches to studying entire pathways or GWAS data. In addition to the usual issues in genetic association studies, particular care is needed in exposure assessment and very large sample sizes are required. Although hypothesis-driven pathway-based and “agnostic” GWAS approaches are generally viewed as opposite poles, we suggest that the two can be usefully married using hierarchical modeling strategies that exploit external pathway knowledge in mining genome-wide data. PMID:20070199

Thomas, Duncan

2010-01-01

111

Gene–environment interactions: key to unraveling the mystery of Parkinson’s disease  

PubMed Central

Parkinson’s disease (PD) is the second most common neurodegenerative disease. The gradual, irreversible loss of dopamine neurons in the substantia nigra isthe signature lesion of PD. Clinical symptoms of PD become apparent when 50–60% of nigral dopamine neurons are lost. PD progresses insidiously for 5–7 years (preclinical period) and then continues to worsen even under the symptomatic treatment. To determine what triggers the disease onset and what drives the chronic, self-propelling neurodegenerative process becomes critical and urgent, since lack of such knowledge impedes the discovery of effective treatments to retard PD progression. At present, available therapeutics only temporarily relieve PD symptoms. While the identification of causative gene defects in familial PD uncovers important genetic influences in this disease, the majority of PD cases are sporadic and idiopathic. The current consensus suggests that PD develops from multiple risk factors including aging, genetic predisposition, and environmental exposure. Here, we briefly review research on the genetic and environmental causes of PD. We also summarize very recent genome-wide association studies on risk gene polymorphisms in the emergence of PD. We highlight the new converging evidence on gene-environment interplay in the development of PD with an emphasis on newly developed multiple-hit PD models involving both genetic lesions and environmental triggers. PMID:21439347

Gao, Hui-Ming; Hong, Jau-shyong

2011-01-01

112

Identifying gene-environment interactions in schizophrenia: contemporary challenges for integrated, large-scale investigations.  

PubMed

Recent years have seen considerable progress in epidemiological and molecular genetic research into environmental and genetic factors in schizophrenia, but methodological uncertainties remain with regard to validating environmental exposures, and the population risk conferred by individual molecular genetic variants is small. There are now also a limited number of studies that have investigated molecular genetic candidate gene-environment interactions (G × E), however, so far, thorough replication of findings is rare and G × E research still faces several conceptual and methodological challenges. In this article, we aim to review these recent developments and illustrate how integrated, large-scale investigations may overcome contemporary challenges in G × E research, drawing on the example of a large, international, multi-center study into the identification and translational application of G × E in schizophrenia. While such investigations are now well underway, new challenges emerge for G × E research from late-breaking evidence that genetic variation and environmental exposures are, to a significant degree, shared across a range of psychiatric disorders, with potential overlap in phenotype. PMID:24860087

van Os, Jim; Rutten, Bart P; Myin-Germeys, Inez; Delespaul, Philippe; Viechtbauer, Wolfgang; van Zelst, Catherine; Bruggeman, Richard; Reininghaus, Ulrich; Morgan, Craig; Murray, Robin M; Di Forti, Marta; McGuire, Philip; Valmaggia, Lucia R; Kempton, Matthew J; Gayer-Anderson, Charlotte; Hubbard, Kathryn; Beards, Stephanie; Stilo, Simona A; Onyejiaka, Adanna; Bourque, Francois; Modinos, Gemma; Tognin, Stefania; Calem, Maria; O'Donovan, Michael C; Owen, Michael J; Holmans, Peter; Williams, Nigel; Craddock, Nicholas; Richards, Alexander; Humphreys, Isla; Meyer-Lindenberg, Andreas; Leweke, F Markus; Tost, Heike; Akdeniz, Ceren; Rohleder, Cathrin; Bumb, J Malte; Schwarz, Emanuel; Alptekin, Köksal; Üçok, Alp; Saka, Meram Can; Atba?o?lu, E Cem; Gülöksüz, Sinan; Gumus-Akay, Guvem; Cihan, Burçin; Karada?, Hasan; Soygür, Haldan; Cankurtaran, Eylem ?ahin; Ulusoy, Semra; Akdede, Berna; Binbay, Tolga; Ayer, Ahmet; Noyan, Handan; Karaday?, Gül?ah; Akturan, Elçin; Ula?, Halis; Arango, Celso; Parellada, Mara; Bernardo, Miguel; Sanjuán, Julio; Bobes, Julio; Arrojo, Manuel; Santos, Jose Luis; Cuadrado, Pedro; Rodríguez Solano, José Juan; Carracedo, Angel; García Bernardo, Enrique; Roldán, Laura; López, Gonzalo; Cabrera, Bibiana; Cruz, Sabrina; Díaz Mesa, Eva Ma; Pouso, María; Jiménez, Estela; Sánchez, Teresa; Rapado, Marta; González, Emiliano; Martínez, Covadonga; Sánchez, Emilio; Olmeda, Ma Soledad; de Haan, Lieuwe; Velthorst, Eva; van der Gaag, Mark; Selten, Jean-Paul; van Dam, Daniella; van der Ven, Elsje; van der Meer, Floor; Messchaert, Elles; Kraan, Tamar; Burger, Nadine; Leboyer, Marion; Szoke, Andrei; Schürhoff, Franck; Llorca, Pierre-Michel; Jamain, Stéphane; Tortelli, Andrea; Frijda, Flora; Vilain, Jeanne; Galliot, Anne-Marie; Baudin, Grégoire; Ferchiou, Aziz; Richard, Jean-Romain; Bulzacka, Ewa; Charpeaud, Thomas; Tronche, Anne-Marie; De Hert, Marc; van Winkel, Ruud; Decoster, Jeroen; Derom, Catherine; Thiery, Evert; Stefanis, Nikos C; Sachs, Gabriele; Aschauer, Harald; Lasser, Iris; Winklbaur, Bernadette; Schlögelhofer, Monika; Riecher-Rössler, Anita; Borgwardt, Stefan; Walter, Anna; Harrisberger, Fabienne; Smieskova, Renata; Rapp, Charlotte; Ittig, Sarah; Soguel-dit-Piquard, Fabienne; Studerus, Erich; Klosterkötter, Joachim; Ruhrmann, Stephan; Paruch, Julia; Julkowski, Dominika; Hilboll, Desiree; Sham, Pak C; Cherny, Stacey S; Chen, Eric Y H; Campbell, Desmond D; Li, Miaoxin; Romeo-Casabona, Carlos María; Emaldi Cirión, Aitziber; Urruela Mora, Asier; Jones, Peter; Kirkbride, James; Cannon, Mary; Rujescu, Dan; Tarricone, Ilaria; Berardi, Domenico; Bonora, Elena; Seri, Marco; Marcacci, Thomas; Chiri, Luigi; Chierzi, Federico; Storbini, Viviana; Braca, Mauro; Minenna, Maria Gabriella; Donegani, Ivonne; Fioritti, Angelo; La Barbera, Daniele; La Cascia, Caterina Erika; Mulè, Alice; Sideli, Lucia; Sartorio, Rachele; Ferraro, Laura; Tripoli, Giada; Seminerio, Fabio; Marinaro, Anna Maria; McGorry, Patrick; Nelson, Barnaby; Amminger, G Paul; Pantelis, Christos; Menezes, Paulo R; Del-Ben, Cristina M; Gallo Tenan, Silvia H; Shuhama, Rosana; Ruggeri, Mirella; Tosato, Sarah; Lasalvia, Antonio; Bonetto, Chiara; Ira, Elisa; Nordentoft, Merete; Krebs, Marie-Odile; Barrantes-Vidal, Neus; Cristóbal, Paula; Kwapil, Thomas R; Brietzke, Elisa; Bressan, Rodrigo A; Gadelha, Ary; Maric, Nadja P; Andric, Sanja; Mihaljevic, Marina; Mirjanic, Tijana

2014-07-01

113

The role of linkage disequilibrium in case-only studies of gene-environment interactions.  

PubMed

Gene-environment (G × E) interactions have been invoked to account, at least in part, for the gap between the known heritability of common human diseases and the phenotypic variation hitherto explained by genetic variants. Noteworthy in this context, a case-only (CO) design has been proposed in the past as a means to detect G × E interactions possibly more efficiently than by using classical case-control and cohort designs. So far, however, most CO studies have followed a candidate (or single) gene approach, and the genome-wide utility of the CO design is still more or less unknown. In particular, the way in which linkage disequilibrium (LD) impacts upon the chance to detect G × E interaction through the analysis of proxy markers has not been studied in much detail before. Therefore, we systematically assessed the power to indirectly detect a given G × E interaction through exploiting LD in a CO design. Our simulations revealed a strong relationship between LD and detection power that was subsequently validated in a real colorectal cancer data set. PMID:25304818

Yadav, Pankaj; Freitag-Wolf, Sandra; Lieb, Wolfgang; Krawczak, Michael

2015-01-01

114

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

PubMed Central

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

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

2012-01-01

115

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

PubMed Central

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

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

116

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

PubMed Central

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

Cash-Padgett, Tyler; Jaaro-Peled, Hanna

2013-01-01

117

Adaptive passive fathometer processing.  

PubMed

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

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

2010-04-01

118

A model of gene-gene and gene-environment interactions and its implications for targeting environmental interventions by genotype  

PubMed Central

Background The potential public health benefits of targeting environmental interventions by genotype depend on the environmental and genetic contributions to the variance of common diseases, and the magnitude of any gene-environment interaction. In the absence of prior knowledge of all risk factors, twin, family and environmental data may help to define the potential limits of these benefits in a given population. However, a general methodology to analyze twin data is required because of the potential importance of gene-gene interactions (epistasis), gene-environment interactions, and conditions that break the 'equal environments' assumption for monozygotic and dizygotic twins. Method A new model for gene-gene and gene-environment interactions is developed that abandons the assumptions of the classical twin study, including Fisher's (1918) assumption that genes act as risk factors for common traits in a manner necessarily dominated by an additive polygenic term. Provided there are no confounders, the model can be used to implement a top-down approach to quantifying the potential utility of genetic prediction and prevention, using twin, family and environmental data. The results describe a solution space for each disease or trait, which may or may not include the classical twin study result. Each point in the solution space corresponds to a different model of genotypic risk and gene-environment interaction. Conclusion The results show that the potential for reducing the incidence of common diseases using environmental interventions targeted by genotype may be limited, except in special cases. The model also confirms that the importance of an individual's genotype in determining their risk of complex diseases tends to be exaggerated by the classical twin studies method, owing to the 'equal environments' assumption and the assumption of no gene-environment interaction. In addition, if phenotypes are genetically robust, because of epistasis, a largely environmental explanation for shared sibling risk is plausible, even if the classical heritability is high. The results therefore highlight the possibility – previously rejected on the basis of twin study results – that inherited genetic variants are important in determining risk only for the relatively rare familial forms of diseases such as breast cancer. If so, genetic models of familial aggregation may be incorrect and the hunt for additional susceptibility genes could be largely fruitless. PMID:17029623

Wallace, Helen M

2006-01-01

119

Gene-environment interactions in wet beriberi: effects of thiamine depletion in CD36-defect rats.  

PubMed

Selective vulnerability to thiamine deficiency is known to occur between individuals and within different tissues. However, no comprehensive explanation for this has been found, and there are no reports that reproduce the cardiovascular manifestations of human wet beriberi in animals. We hypothesized that the distinction of substrate reliance, namely, the primary dependency on glucose as substrate, could be an underlying factor in the selective vulnerability of thiamine deficiency. In the setting of impaired fatty acid entry, which occurs in CD36-defect rats, substrate reliance shifts from fatty acid to glucose, which would be expected to lead to a susceptibility to thiamine deficiency. Genomic DNA was analyzed for CD36 defects in three cognate strains of rats [spontaneously hypertensive rats (SHR)/NCrj, SHR/Izm, and Wistar-Kyoto (WKY)/NCrj], which identified the presence of a CD36 defect in SHR/NCrj rats but not in SHR/Izm and WKY/NCrj rats. Treatment with 2 wk of thiamine-depleted chow on 4-wk-old rats of each of these strains resulted in increased body and lung weight in the SHR/NCrj rats but not in the SHR/Izm and WKY/NCrj rats. The increased lung weight in the SHR/NCrj rats was accompanied with histological changes of congestive vasculopathy, which were not observed in either the SHR/Izm or the WKY/NCrj rats. Thiamine-deficient 12-wk-old SHR/NCrj rats demonstrated increased body weight (305.6 +/- 6.2 g in thiamine-deficient rats vs. 280.8 +/- 9.1 g in control; P < 0.0001), lactic acidemia (pH, 7.322 +/- 0.026 in thiamine-deficient rats vs. 7.443 +/- 0.016 in control; P < 0.0001; lactate, 2.42 +/- 0.28 mM in thiamine-deficient rats vs. 1.20 +/- 0.11 mM in control; P < 0.0001) and reduced systemic vascular resistance (4.61 +/- 0.42 x 104 dyn.s.cm-5 in thiamine-deficient rats vs. 6.55 +/- 1.36 x 104 dyn.s.cm-5 in control; P < 0.0001) with high cardiac output (186.0 +/- 24.7 ml in thiamine-deficient rats vs. 135.4 +/- 27.2 ml in control; P < 0.0019). In conclusion, SHR/NCrj rats harboring a genetic defect of long-chain fatty acid uptake present the relevant clinical cardiovascular signs of human wet beriberi, strongly indicating a close gene-environment interaction in wet beriberi. PMID:12969879

Tanaka, Takao; Kono, Tatsuji; Terasaki, Fumio; Kintaka, Taigo; Sohmiya, Koichi; Mishima, Takayuki; Kitaura, Yasushi

2003-10-01

120

Toward a 3D model of human brain development for studying gene/environment interactions  

PubMed Central

This project aims to establish and characterize an in vitro model of the developing human brain for the purpose of testing drugs and chemicals. To accurately assess risk, a model needs to recapitulate the complex interactions between different types of glial cells and neurons in a three-dimensional platform. Moreover, human cells are preferred over cells from rodents to eliminate cross-species differences in sensitivity to chemicals. Previously, we established conditions to culture rat primary cells as three-dimensional aggregates, which will be humanized and evaluated here with induced pluripotent stem cells (iPSCs). The use of iPSCs allows us to address gene/environment interactions as well as the potential of chemicals to interfere with epigenetic mechanisms. Additionally, iPSCs afford us the opportunity to study the effect of chemicals during very early stages of brain development. It is well recognized that assays for testing toxicity in the developing brain must consider differences in sensitivity and susceptibility that arise depending on the time of exposure. This model will reflect critical developmental processes such as proliferation, differentiation, lineage specification, migration, axonal growth, dendritic arborization and synaptogenesis, which will probably display differences in sensitivity to different types of chemicals. Functional endpoints will evaluate the complex cell-to-cell interactions that are affected in neurodevelopment through chemical perturbation, and the efficacy of drug intervention to prevent or reverse phenotypes. The model described is designed to assess developmental neurotoxicity effects on unique processes occurring during human brain development by leveraging human iPSCs from diverse genetic backgrounds, which can be differentiated into different cell types of the central nervous system. Our goal is to demonstrate the feasibility of the personalized model using iPSCs derived from individuals with neurodevelopmental disorders caused by known mutations and chromosomal aberrations. Notably, such a human brain model will be a versatile tool for more complex testing platforms and strategies as well as research into central nervous system physiology and pathology. PMID:24564953

2013-01-01

121

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

PubMed Central

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

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

122

Correlation of serum IgG concentration in foals and refractometry index of the dam's pre- and post-parturient colostrums: an assessment for failure of passive transfer in foals.  

PubMed

The object of this study was to evaluate the usefulness of measuring the differences in the values of the serum total protein (DVSTP) concentration of foals and the refractometry index (DVRI) of the milk of dams before and after nursing of the colostrum for assessing failure of passive transfer (FPT) in foals. Serum samples from 31 foals were collected before the first nursing and other 1 to 6 times between 4 and 24 hr after birth. Paired colostrum and milk samples were collected from 14 of their dams at the same time. Serum samples were analyzed for IgG concentration using a single radial immunodiffusion (SRID) test (98 samples) and total protein concentration using a temperature-compensating refractometer (98 samples). Colostrum and milk samples were analyzed for refractometry index (RI) using a Brix refractometer (71 samples). DVSTP concentration and DVRI were significantly correlated with serum IgG concentration. The negative predictive values (NPVs) of DVSTP concentration for detecting serum IgG concentrations<400 mg/dl and<800 mg/dl were 98.2% and 91.3% when the cutoff value is set to 0.4 mg/dl and 0.8 mg/dl, respectively. Furthermore, the NPVs of DVRI for detecting serum IgG concentrations<400 mg/dl and<800 mg/dl were 97.3% and 96.3% when the cutoff value is set to 6% and 10%, respectively. The results suggest that measurement of DVRI is useful in assessing FPT as an initial "stall-side" screening test, because it is easy, inexpensive to perform and allows for rapid interpretation. PMID:22785030

Korosue, Kenji; Murase, Harutaka; Sato, Fumio; Ishimaru, Mutsuki; Kotoyori, Yasumitsu; Nambo, Yasuo

2012-11-01

123

Passive detection of moving targets  

NASA Astrophysics Data System (ADS)

The paper presents the concept of passive detection of moving targets based on thermal radiation in microwave region. Up to now the passive detection of moving targets, especially airplanes and ground vehicles is performed using infrared sensor. The microwave radiometric methods are now widely used in many other fields of applications, such as radio astronomy, remote sensing, medicine, pollution control, mine detection and other. All these methods are based on measurement of power of thermal noise radiated by hot surface. The usage of power-only information is usually not sufficient to discriminate between moving and stationary target. To sense the target movement different phenomena can be applied. The most fundamental one is Doppler shift of the spectrum of radiating thermal noise. To perform this task complex envelope of received signal must be recorded and Doppler processing must be applied. The Doppler and time correlations are widely used in radio astronomy, for sensing the weather and for high-resolution image creation, but up to now was not exploited for moving target indication, so important in ATC applications. The fundamental problem - distinction between stationary and moving targets is performed by calculating range-Doppler correlation between thermal signals obtained from different localization in multi-static radiometric antenna constellation. Further more, using correlation principles, it is possible to obtain high resolution images of the detected objects.

Kulpa, Krzysztof S.

2005-09-01

124

Physics of passive solar buildings  

SciTech Connect

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.

Balcomb, J.D.

1981-01-01

125

Passive magnetic bearing configurations  

DOEpatents

A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

Post, Richard F. (Walnut Creek, CA)

2011-01-25

126

Passive solar building design  

SciTech Connect

This book presents the basic principles of passive solar design and offers quantitative design aids in the form of microcomputer programs to stimulate innovative passive designs. These programs are unlike most others, which focus on conventional designs. The volume also covers landscaping, energy conservation and aesthetics.

Carter, C.; De Villiers, J.

1987-01-01

127

Passive solar food system  

Microsoft Academic Search

A move towards residential self-sufficiency, the Passive Solar Food System (PSFS), was designed to produce both vegetables and high quality animal protein in the form of fish and shellfish. Housed in an attached, passively heated solar greenhouse, the aquaculture tank is designed to provide much of the thermal storage for the PSFS. Additional energy storage mass is provided by the

R. G. Gregoire; C. M. Gregoire

1980-01-01

128

Passive solar construction handbook  

SciTech Connect

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)

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

1981-08-01

129

Passive Optical PassiveOpticalNetworks Contents  

E-print Network

Cable-TV (CATV) infrastructures · Power Line Communication ­ PLC · Wireless access technologies ­ Local, large distances · Low power consumption · Large Bandwidth, many broadband users · Requires new fiber line ­ Curb Switch power in the field ­ 2N+2 transcievers #12;PassiveOpticalNetworks Optical Access

Mellia, Marco

130

A powerful statistical method identifies novel loci associated with diastolic blood pressure triggered by nonlinear gene-environment interaction  

PubMed Central

The genetic basis of blood pressure often involves multiple genetic factors and their interactions with environmental factors. Gene-environment interaction is assumed to play an important role in determining individual blood pressure variability. Older people are more prone to high blood pressure than younger ones and the risk may not display a linear trend over the life span. However, which gene shows sensitivity to aging in its effect on blood pressure is not clear. In this work, we allowed the genetic effect to vary over time and propose a varying-coefficient model to identify potential genetic players that show nonlinear response across different age stages. We detected 2 novel loci, gene MIR1263 (a microRNA coding gene) on chromosome 3 and gene UNC13B on chromosome 9, that are nonlinearly associated with diastolic blood pressure. Further experimental validation is needed to confirm this finding. PMID:25519336

2014-01-01

131

Gene-environment interaction testing in family-based association studies with phenotypically ascertained samples: a causal inference approach.  

PubMed

We propose a method for testing gene-environment (G × E) interactions on a complex trait in family-based studies in which a phenotypic ascertainment criterion has been imposed. This novel approach employs G-estimation, a semiparametric estimation technique from the causal inference literature, to avoid modeling of the association between the environmental exposure and the phenotype, to gain robustness against unmeasured confounding due to population substructure, and to acknowledge the ascertainment conditions. The proposed test allows for incomplete parental genotypes. It is compared by simulation studies to an analogous conditional likelihood-based approach and to the QBAT-I test, which also invokes the G-estimation principle but ignores ascertainment. We apply our approach to a study of chronic obstructive pulmonary disorder. PMID:22084302

Fardo, David W; Liu, Jinze; Demeo, Dawn L; Silverman, Edwin K; Vansteelandt, Stijn

2012-07-01

132

Conceptual Shifts Needed to Understand the Dynamic Interactions of Genes, Environment, Epigenetics, Social Processes, and Behavioral Choices  

PubMed Central

Social and behavioral research in public health is often intimately tied to profound, but frequently neglected, biological influences from underlying genetic, environmental, and epigenetic events. The dynamic interplay between the life, social, and behavioral sciences often remains underappreciated and underutilized in addressing complex diseases and disorders and in developing effective remediation strategies. Using a case-study format, we present examples as to how the inclusion of genetic, environmental, and epigenetic data can augment social and behavioral health research by expanding the parameters of such studies, adding specificity to phenotypic assessments, and providing additional internal control in comparative studies. We highlight the important roles of gene–environment interactions and epigenetics as sources of phenotypic change and as a bridge between the life and social and behavioral sciences in the development of robust interdisciplinary analyses. PMID:23927503

Niculescu, Mihai D.; Jackson, Robert T.

2013-01-01

133

Gene × Environment interaction and resilience: effects of child maltreatment and serotonin, corticotropin releasing hormone, dopamine, and oxytocin genes.  

PubMed

In this investigation, gene-environment interaction effects in predicting resilience in adaptive functioning among maltreated and nonmaltreated low-income children (N = 595) were examined. A multicomponent index of resilient functioning was derived and levels of resilient functioning were identified. Variants in four genes (serotonin transporter linked polymorphic region, corticotropin releasing hormone receptor 1, dopamine receptor D4-521C/T, and oxytocin receptor) were investigated. In a series of analyses of covariance, child maltreatment demonstrated a strong negative main effect on children's resilient functioning, whereas no main effects for any of the genotypes of the respective genes were found. However, gene-environment interactions involving genotypes of each of the respective genes and maltreatment status were obtained. For each respective gene, among children with a specific genotype, the relative advantage in resilient functioning of nonmaltreated compared to maltreated children was stronger than was the case for nonmaltreated and maltreated children with other genotypes of the respective gene. Across the four genes, a composite of the genotypes that more strongly differentiated resilient functioning between nonmaltreated and maltreated children provided further evidence of genetic variations influencing resilient functioning in nonmaltreated children, whereas genetic variation had a negligible effect on promoting resilience among maltreated children. Additional effects were observed for children based on the number of subtypes of maltreatment children experienced, as well as for abuse and neglect subgroups. Finally, maltreated and nonmaltreated children with high levels of resilience differed in their average number of differentiating genotypes. These results suggest that differential resilient outcomes are based on the interaction between genes and developmental experiences. PMID:22559122

Cicchetti, Dante; Rogosch, Fred A

2012-05-01

134

Passive microfluidic interconnects  

E-print Network

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 ...

Jonnalagadda, Aparna S

2005-01-01

135

The hidden efficacy of interventions: gene×environment experiments from a differential susceptibility perspective.  

PubMed

The efficacy of interventions might be underestimated or even go undetected as a main effect when it is hidden in gene-by-environment (G×E) interactions. This review moves beyond the problems thwarting correlational G×E research to propose genetic differential susceptibility experiments. G×E experiments can test the bright side as well as the dark side of the moderating role of genotypes traditionally considered to represent vulnerability to negative conditions. The differential susceptibility model predicts that carriers of these risk genotypes profit most from interventions changing the environment for the better. The evolutionary background of G×E and differential susceptibility is discussed, and statistical methods for the analysis of differential susceptibility (versus diathesis stress) are reviewed. Then, based on results from 22 randomized G×E experiments, meta-analytic evidence for the differential susceptibility model is presented. Intervention effects are much stronger in the susceptible genotypes than in the nonsusceptible genotypes. The final sections suggest possibilities to broaden the G component in the G×E equation by including genetic pathways, and to broaden the E component by including methylation level and gene expression as promising ways to probe the concept of the environment more deeply and address the perennial issue of what works for whom. PMID:25148854

Bakermans-Kranenburg, Marian J; van IJzendoorn, Marinus H

2015-01-01

136

Paraoxonase gene variants are associated with autism in North America, but not in Italy: possible regional specificity in gene–environment interactions  

Microsoft Academic Search

Organophosphates (OPs) are routinely used as pesticides in agriculture and as insecticides within the household. Our prior work on Reelin and APOE delineated a gene–environment interactive model of autism pathogenesis, whereby genetically vulnerable individuals prenatally exposed to OPs during critical periods in neurodevelopment could undergo altered neuronal migration, resulting in an autistic syndrome. Since household use of OPs is far

M D'Amelio; I Ricci; R Sacco; X Liu; L D'Agruma; L A Muscarella; V Guarnieri; R Militerni; C Bravaccio; M Elia; C Schneider; R Melmed; S Trillo; T Pascucci; S Puglisi-Allegra; K-L Reichelt; F Macciardi; J J A Holden; A M Persico

2005-01-01

137

Evidence of gene-environment interactions between common breast cancer susceptibility loci and established environmental risk factors.  

PubMed

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

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; Silva, Isabel dos Santos; 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; Mannermaa, Arto; Kataja, Vesa; Kosma, Veli-Matti; Hartikainen, Jaana M; 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

138

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

PubMed Central

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

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

139

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

PubMed

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

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

2013-09-01

140

Gene-Environment Interaction Effects on the Development of Immune Responses in the 1st Year of Life  

PubMed Central

Asthma is a common disease that results from both genetic and environmental risk factors. Children attending day care in the 1st year of life have lower risks for developing asthma, although the mechanism for this “day care” effect is largely unknown. We investigated the interactions between day care exposure in the 1st 6 mo of life and genotypes for 72 polymorphisms at 45 candidate loci and their effects on cytokine response profiles and on the development of atopic phenotypes in the 1st year of life in the Childhood Onset of Asthma (COAST) cohort of children. Six interactions (at four polymorphisms in three loci) with “day care” that had an effect on early-life immune phenotypes were significant at P<.001. The estimated false-discovery rate was 33%, indicating that an estimated four P values correspond to true associations. Moreover, the “day care” effect at some loci was accounted for by the increased number of viral infections among COAST children attending day care, whereas interactions at other loci were independent of the number of viral infections, indicating the presence of additional risk factors associated with day care environment. This study identified significant gene-environment interactions influencing the early patterning of the immune system and the subsequent development of asthma and highlights the importance of considering environmental risk factors in genetic analyses. PMID:15726497

Hoffjan, Sabine; Nicolae, Dan; Ostrovnaya, Irina; Roberg, Kathy; Evans, Michael; Mirel, Daniel B.; Steiner, Lori; Walker, Karen; Shult, Peter; Gangnon, Ronald E.; Gern, James E.; Martinez, Fernando D.; Lemanske, Robert F.; Ober, Carole

2005-01-01

141

Pulse pressure relation to aortic and left ventricular structure in the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study.  

PubMed

High pulse pressure, a major cardiovascular risk factor, has been attributed to medial elastic fiber degeneration and aortic dilation, which transfers hemodynamic load to stiffer collagen. However, recent studies suggest higher pulse pressure is instead associated with smaller aortic diameter. Thus, we sought to elucidate relations of pulse pressure with aortic stiffness and aortic and cardiac dimensions. We used magnetic resonance imaging to examine relationships of pulse pressure with lumen area and wall stiffness and thickness in the thoracic aorta and left ventricular structure in 526 participants (72-94 years of age, 295 women) in the community-based Age, Gene/Environment Susceptibility-Reykjavik Study. In a multivariable model that adjusted for age, sex, height, weight, and standard vascular risk factors, central pulse pressure had a negative relationship with aortic lumen area (all effects expressed as mm Hg/SD; B=-8.1±1.2; P<0.001) and positive relationships with left ventricular end-diastolic volume (B=3.8±1.0; P<0.001), carotid-femoral pulse wave velocity (B=3.6±1.0; P<0.001), and aortic wall area (B=3.0±1.2; P=0.015). Higher pulse pressure in older people is associated with smaller aortic lumen area and greater aortic wall stiffness and thickness and left ventricular volume. Relationships of larger ventricular volume and smaller aortic lumen with higher pulse pressure suggest mismatch in hemodynamic load accommodation by the heart and aorta in older people. PMID:25024287

Torjesen, Alyssa A; Sigurðsson, Sigurður; Westenberg, Jos J M; Gotal, John D; Bell, Vanessa; Aspelund, Thor; Launer, Lenore J; de Roos, Albert; Gudnason, Vilmundur; Harris, Tamara B; Mitchell, Gary F

2014-10-01

142

Gene-environment interactions in determining differences in genetic susceptibility to cancer in subsites of the head and neck.  

PubMed

Genetic differences in susceptibility to cancer in subsites of the head and neck were investigated in a case-control study involving 750 cases of cancers of the oral cavity, larynx, or pharynx, and an equal number of healthy controls. The prevalence of variant genotypes of cytochrome P450 (CYP) 1A1, 1B1, 2E1, or glutathione-S-transferase M1 (null) in cases suggests that polymorphisms in drug metabolizing enzymes (DMEs) modify cancer risk within subsites of the head and neck. Tobacco or alcohol use was found to increase the risk in cases of laryngeal, pharyngeal, or oral cavity cancers. Interaction between genetic variation in DMEs and tobacco smoke (or smoking) exposures conferred significant risk for laryngeal cancer. Likewise, strong associations of the polymorphic genotypes of DMEs with cases of pharyngeal and oral cavity cancer who were tobacco chewers or alcohol users demonstrate that gene-environment interactions may explain differences in genetic susceptibility for cancers of the oral cavity, larynx, and pharynx. Environ. Mol. Mutagen., 2014. © 2014 Wiley Periodicals, Inc. PMID:25399842

Maurya, Shailendra S; Katiyar, Tridiv; Dhawan, Ankur; Singh, Sudhir; Jain, Swatantra K; Pant, Mohan C; Parmar, Devendra

2014-11-14

143

The Influence of Major Life Events on Economic Attitudes in a World of Gene-Environment Interplay.  

PubMed

The role of "genes" on political attitudes has gained attention across disciplines. However, person-specific experiences have yet to be incorporated into models that consider genetic influences. Relying on a gene-environment interplay approach, this study explicates how life-events, such as losing one's job or suffering a financial loss, influence economic policy attitudes. The results indicate genetic and environmental variance on support for unions, immigration, capitalism, socialism and property tax is moderated by financial risks. Changes in the magnitude of genetic influences, however, are temporary. After two years, the phenotypic effects of the life events remain on most attitudes, but changes in the sources of individual differences do not. Univariate twin models that estimate the independent contributions of genes and environment on the variation of attitudes appear to provide robust baseline indicators of sources of individual differences. These estimates, however, are not event or day specific. In this way, genetic influences add stability, while environment cues change, and this process is continually updated. PMID:24860199

Hatemi, Peter K

2013-10-01

144

Probability Distribution Function of Passive Scalars in Shell Models  

NASA Astrophysics Data System (ADS)

A shell-model version of passive scalar problem is introduced, which is inspired by the model of K. Ohkitani and M. Yakhot [K. Ohkitani and M. Yakhot, Phys. Rev. Lett. 60 (1988) 983; K. Ohkitani and M. Yakhot, Prog. Theor. Phys. 81 (1988) 329]. As in the original problem, the prescribed random velocity field is Gaussian and ? correlated in time. Deterministic differential equations are regarded as nonlinear Langevin equation. Then, the Fokker Planck equations of PDF for passive scalars are obtained and solved numerically. In energy input range (n < 5, n is the shell number.), the probability distribution function (PDF) of passive scalars is near the Gaussian distribution. In inertial range (5 <= n <= 16) and dissipation range (n >= 17), the probability distribution function (PDF) of passive scalars has obvious intermittence. And the scaling power of passive scalar is anomalous. The results of numerical simulations are compared with experimental measurements.

Zhang, Xiao-Qiang; Wang, Guang-Rui; Chen, Shi-Gang

2008-04-01

145

Method of passivating semiconductor surfaces  

DOEpatents

A method is described for passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

Wanlass, M.W.

1990-06-19

146

Method of passivating semiconductor surfaces  

DOEpatents

A method of passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

Wanlass, Mark W. (Golden, CO)

1990-01-01

147

Human detection range by active Doppler and passive ultrasonic methods  

NASA Astrophysics Data System (ADS)

Human motion can be characterized as a periodic, temporal process of a mechanical system and can be detected by active and passive ultrasonic methods. The active method utilizes Doppler ultrasound to characterize the motion of individual body parts (torso, legs, arms, etc.). The friction forces of a footstep produce broadband sound signals that can be measured by passive ultrasonic sensors. Comparison of Doppler motion and the footstep signals reveals a strong correlation of features between the footstep friction and the maximum Doppler shift. This article presents test results from measurements of human motion and evaluates the detection range for the passive ultrasonic method.

Ekimov, Alexander; Sabatier, James M.

2008-04-01

148

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

PubMed Central

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

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

149

Novel Likelihood Ratio Tests for Screening Gene-Gene and Gene-Environment Interactions with Unbalanced Repeated-Measures Data  

PubMed Central

There has been extensive literature on modeling gene-gene interaction (GGI) and gene-environment interaction (GEI) in case-control studies with limited literature on statistical methods for GGI and GEI in longitudinal cohort studies. We borrow ideas from the classical two-way analysis of variance (ANOVA) literature to address the issue of robust modeling of interactions in repeated-measures studies. While classical interaction models proposed by Tukey and Mandel have interaction structures as a function of main effects, a newer class of models, additive main effects and multiplicative interaction (AMMI) models, do not have similar restrictive assumptions on the interaction structure. AMMI entails a singular value decomposition of the cell residual matrix after fitting the additive main effects and has been shown to perform well across various interaction structures. We consider these models for testing GGI and GEI from two perspectives: likelihood ratio test based on cell means and a regression based approach using individual observations. Simulation results indicate that both approaches for AMMI models lead to valid tests in terms of maintaining the type I error rate, with the regression approach having better power properties. The performance of these models was evaluated across different interaction structures and 12 common epistasis patterns. In summary, AMMI model is robust with respect to misspecified interaction structure and is a useful screening tool for interaction even in the absence of main effects. We use the proposed methods to examine the interplay between the hemochromatosis gene and cumulative lead exposure on pulse pressure in the Normative Aging Study. PMID:23798480

Ko, Yi-An; Saha-Chaudhuri, Paramita; Park, Sung Kyun; Vokonas, Pantel Steve; Mukherjee, Bhramar

2013-01-01

150

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

PubMed Central

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

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

151

Gene-Gene and Gene-Environment Interactions Involving HLA-DRB1, PTPN22, and Smoking in Two Subsets of Rheumatoid Arthritis  

Microsoft Academic Search

Gene-gene and gene-environment interactions are key features in the development of rheumatoid arthritis (RA) and other complex diseases. The aim of this study was to use and compare three different definitions of interaction between the two major genetic risk factors of RA—the HLA-DRB1 shared epitope (SE) alleles and the PTPN22 R620W allele—in three large case-control studies: the Swedish Epidemiological Investigation

Henrik Källberg; Leonid Padyukov; Robert M. Plenge; Johan Rönnelid; Peter K. Gregersen; Annette H. M. van der Helm-van Mil; Rene E. M. Toes; Tom W. Huizinga; Lars Klareskog; Lars Alfredsson

2007-01-01

152

Passive optoelectronic tag  

NASA Astrophysics Data System (ADS)

In response to a pressing demand for tagging systems and technologies developing, Physical Optics Corporation (POC) proposes a novel Passive Optoelectronical (POET) Tag system. The POET tag is an omnidirectional (360° in azimuth), with up to 180° field-of-view in elevation, retroreflection optical system with a high frequency multiple quantum well (MQW) light intensity modulator for free space IR optical communication. The POET tag optical scheme is a compact, high quality generalized fish-eye lens with telecentric arrangement in image space. The telecentric arrangement in image space provides perfect omnidirectional retroreflection of a recall beam and an optimum divergent of light at the MQW providing maximum modulation contrast ratios. The important POET tag features are low power consumption, zero probability of jamming and intercepting (high security of communication,) because it operates in a passive retroreflection mode with a highly-directed optical beam.

Agurok, Il'ya P.; Jannson, Tomasz P.; Savant, Gajendra D.

2003-09-01

153

Passive fetal monitoring sensor  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

154

Passive application of masonry products  

SciTech Connect

The sensible thermal storage provided by masonry and concrete is what is needed in the current thermal storage media for passive solar energy systems. Masonry, in passive heating, in direct gain passive, in attached sunspace, and in solar cooling, is suggested. Masonry stores thermal energy efficiently, with less cost, and it can be a structural element of the building. These characteristics highly recommend masonry for thermal storage.

Szoke, S.S.

1982-06-01

155

Passive solar design handbook  

SciTech Connect

The Passive Solar Design Handbook, Volume Three updates Volume Two by presenting extensive new data on the optimum mix of conservation and solar direct gain, sunspaces, thermal storage walls, and solar radiation. The direct gain, thermal storage wall, and solar radiation data are greatly expanded relative to the Volume 2 coverage. The needed flexibility to analyze a variety of system designs is accommodated by the large number of reference designs to be encompassed - 94 in contrast to 6 in Volume two - and the large amount of sensitivity data for direct gain and sunspace systems - approximately 1100 separate curves.

Jones, R.W.

1981-01-01

156

Passive-solar construction handbook  

SciTech Connect

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)

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

1981-02-01

157

Fly ash carbon passivation  

DOEpatents

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.

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

2013-05-14

158

Mechanical passive logic module  

NASA Astrophysics Data System (ADS)

Nothing from nothing gives simple simile, but something from nothing is an interesting and challenging task. Adolf Lohmann once proposed 'do nothing machine' in optics, which only copies input to output. Passive logic module (PALM) is a special type of 'do nothing machine' which can converts inputs into one of 16 possible binary outputs. This logic module is not like the conventional irreversible one. It is a simple type of reversible Turing machine. In this manuscript we discussed and demonstrated PALM using mechanical movement of plane mirrors. Also we discussed the theoretical model of micro electro mechanical system (MEMS) based PALM in this manuscript. It may have several valuable properties such as passive operation (no need for nonlinear elements as other logic device require) and modular logic (one device implementing any Boolean logic function with simple internal changes). The result is obtained from the demonstration by only looking up the output. No calculation is required to get the result. Not only that, PALM is a simple type of the famous 'billiard ball machine', which also discussed in this manuscript.

Chattopadhyay, Tanay; Caulfield, H. John

2015-02-01

159

Temperature initiated passive cooling system  

DOEpatents

A passive cooling system for cooling an enclosure only when the enclosure temperature exceeds a maximum standby temperature comprises a passive heat transfer loop containing heat transfer fluid having a particular thermodynamic critical point temperature just above the maximum standby temperature. An upper portion of the heat transfer loop is insulated to prevent two phase operation below the maximum standby temperature. 1 fig.

Forsberg, C.W.

1994-11-01

160

Temperature initiated passive cooling system  

DOEpatents

A passive cooling system for cooling an enclosure only when the enclosure temperature exceeds a maximum standby temperature comprises a passive heat transfer loop containing heat transfer fluid having a particular thermodynamic critical point temperature just above the maximum standby temperature. An upper portion of the heat transfer loop is insulated to prevent two phase operation below the maximum standby temperature.

Forsberg, Charles W. (Oak Ridge, TN)

1994-01-01

161

A comparative study of GaSb (100) surface passivation by aqueous and nonaqueous solutions  

NASA Astrophysics Data System (ADS)

We report a nonaqueous passivation regime consisting of Na2S/benzene/15-crown-5/oxidant. The use of a nonpolar, aprotic organic medium required the addition of a specific chelating agent (15-crown-5) to solubilize sodium sulfide, and organic oxidizing agents (anthraquinone, benzophenone, etc.) to act as electron acceptors. The surface optical and chemical properties of GaSb surfaces after aqueous and nonaqueous sulfide treatments were compared. Nonaqueous passivation resulted in higher photoluminescence (PL) intensity, lower oxide content, and a less amount of elemental Sb than aqueous passivation. The PL intensity from passivated surfaces was correlated with the standard reduction potentials of electron acceptors.

Liu, Z. Y.; Kuech, T. F.; Saulys, D. A.

2003-09-01

162

Antireflection/Passivation Step For Silicon Cell  

NASA Technical Reports Server (NTRS)

New process excludes usual silicon oxide passivation. Changes in principal electrical parameters during two kinds of processing suggest antireflection treatment almost as effective as oxide treatment in passivating cells. Does so without disadvantages of SiOx passivation.

Crotty, Gerald T.; Kachare, Akaram H.; Daud, Taher

1988-01-01

163

Passive-Solar-Heating Analysis: a new ASHRAE manual  

SciTech Connect

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.

Balcomb, J.D.

1983-01-01

164

The Oxytocin Receptor Gene (OXTR) in Relation to State Levels of Loneliness in Adolescence: Evidence for Micro-Level Gene-Environment Interactions  

PubMed Central

Previous research has shown that the rs53576 variant of the oxytocin receptor gene (OXTR) is associated with trait levels of loneliness, but results are inconsistent. The aim of the present study is to examine micro-level effects of the OXTR rs53576 variant on state levels of loneliness in early adolescents. In addition, gene-environment interactions are examined between this OXTR variant and positive and negative perceptions of company. Data were collected in 278 adolescents (58% girls), by means of the Experience Sampling Method (ESM). Sampling periods consisted of six days with nine assessments per day. A relation was found between the OXTR rs53576 variant and state loneliness, in girls only. Girls carrying an A allele had higher levels of state loneliness than girls carrying the GG genotype. In addition, adolescents with an A allele were more affected by negative perceptions of company than GG carriers, on weekend days only. No significant gene-environment interactions were found with positive company. Adolescents carrying an A allele were more susceptible to negative environments during weekend days than GG carriers. Our findings emphasize the importance of operationalizing the phenotype and the environment accurately. PMID:24223720

van Roekel, Eeske; Verhagen, Maaike; Scholte, Ron H. J.; Kleinjan, Marloes; Goossens, Luc; Engels, Rutger C. M. E.

2013-01-01

165

Passive containment cooling system  

DOEpatents

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.

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

1994-01-01

166

Passive Ball Capture Joint  

NASA Technical Reports Server (NTRS)

A passive ball capture joint has a sleeve with a plurality of bores distributed about a circumference thereof and formed therethrough at an acute angle relative to the sleeve's longitudinal axis. A spring-loaded retainer is slidingly fitted in each bore and is biased such that, if allowed, will extend at least partially into the sleeve to retain a ball therein. A ring, rotatably mounted about the bores, has an interior wall defining a plurality of shaped races that bear against the spring-loaded retainers. A mechanized rotational force producer is coupled to the ring. The ring can be rotated from a first position (that presses the retainers into the sleeve to lock the ball in place) to a second position (that allows the retainers to springback out of the sleeve to release the ball).

Cloyd, Richard A. (Inventor); Bryan, Thomas C. (Inventor)

2003-01-01

167

Passive containment cooling system  

DOEpatents

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.

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

1994-01-25

168

Passive magnetic bearing system  

DOEpatents

An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

Post, Richard F.

2014-09-02

169

Passive seismic experiment  

NASA Technical Reports Server (NTRS)

The design, deployment, and operation of the Apollo 16 passive seismic experiment (PSE) are discussed. Since activation, all elements of the PSE have operated as planned, with the exception of the sensor thermal control system. Significant progress in the measurement of meteoroid flux in near-earth space has been made, along with dilineation of active moonquake source regions. The data obtained indicate that moonquakes are concentrated at great depth (800 to 1000 km) and that the apparent disparity between meteoroid flux estimtes based on lunar crater counts and those from earth-based observations can be resolved by seismic measurements in favor of the lower flux indicated by the crater count method. The results obtained from the PSE are summarized and their significance is discussed in detail.

Latham, G. V.; Ewing, M.; Press, F.; Sutton, G.; Dorman, J.; Nakamura, Y.; Toksoz, N.; Lammlein, D.; Duennebier, F.

1972-01-01

170

Identifying Sciaenid Critical Spawning Habitats by the Use of Passive Acoustics  

E-print Network

and sonobuoy field surveys. These sounds, produced by males, are species specific, are associated with spawning can be correlated with species and fish size. Sonobuoys were used for passive acoustic surveys, which

Luczkovich, Joseph J.

171

Electrophysiological analysis of the perception of passive movement.  

PubMed

The goal of the present study was to determine the electrophysiological correlate of the threshold of perception of passive motion (TPPM) in a group of healthy individuals. We expect a different pattern of activation over the frontoparietal network produced by the conscious perception of the passive movement. Ten right-handed male volunteers, between 20 and 30 years of age, were submitted to the threshold of perception of passive motion (TPPM) task in a proprioception testing device (PTD). The device was designed to passively move the arm in internal and external rotations about the shoulder joint. Participants were instructed to press a hand-held switch every time movement of the shoulder was detected. Electromyographic (EMG) and electroencephalographic (EEG) activities were acquired during the task. Passive movement of the shoulder joint was followed by a clear and prolonged decrease in the signal magnitude of the electroencephalogram. The electrophysiological correlate of the TPPM was characterized by the establishment of a frontoparietal network, during the processing of somatosensory information. PMID:21596095

Salles, Jose Inacio; Costa, Filipe; Cunha-Cruz, Victor; Cagy, Mauricio; Piedade, Roberto; Ribeiro, Pedro

2011-08-26

172

Passive Vaporizing Heat Sink  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

173

Passive blast pressure sensor  

SciTech Connect

A passive blast pressure sensor for detecting blast overpressures of at least a predetermined minimum threshold pressure. The blast pressure sensor includes a piston-cylinder arrangement with one end of the piston having a detection surface exposed to a blast event monitored medium through one end of the cylinder and the other end of the piston having a striker surface positioned to impact a contact stress sensitive film that is positioned against a strike surface of a rigid body, such as a backing plate. The contact stress sensitive film is of a type which changes color in response to at least a predetermined minimum contact stress which is defined as a product of the predetermined minimum threshold pressure and an amplification factor of the piston. In this manner, a color change in the film arising from impact of the piston accelerated by a blast event provides visual indication that a blast overpressure encountered from the blast event was not less than the predetermined minimum threshold pressure.

King, Michael J.; Sanchez, Roberto J.; Moss, William C.

2013-03-19

174

Passivity indices for symmetrically interconnected distributed systems  

Microsoft Academic Search

In this paper, the passivity indices for both lin- ear and nonlinear multi-agent systems with feedforward and feedback interconnections are derived. For linear systems, the passivity indices are explicitly characterized, while the passivity indices in the nonlinear case are characterized by a set of matrix inequalities. We also focus on symmetric interconnections and specialize the passivity indices results to this

Po Wu; Panos J. Antsaklis

2011-01-01

175

Estimating risks and relative risks in case-base studies under the assumptions of gene-environment independence and Hardy-Weinberg equilibrium.  

PubMed

Many diseases result from the interactions between genes and the environment. An efficient method has been proposed for a case-control study to estimate the genetic and environmental main effects and their interactions, which exploits the assumptions of gene-environment independence and Hardy-Weinberg equilibrium. To estimate the absolute and relative risks, one needs to resort to an alternative design: the case-base study. In this paper, the authors show how to analyze a case-base study under the above dual assumptions. This approach is based on a conditional logistic regression of case-counterfactual controls matched data. It can be easily fitted with readily available statistical packages. When the dual assumptions are met, the method is approximately unbiased and has adequate coverage probabilities for confidence intervals. It also results in smaller variances and shorter confidence intervals as compared with a previous method for a case-base study which imposes neither assumption. PMID:25137392

Chui, Tina Tsz-Ting; Lee, Wen-Chung

2014-01-01

176

A system model for investigating passive electrical properties of neurons.  

PubMed Central

Passive membrane properties of neurons, characterized by a linear voltage response to constant current stimulation, were investigated by busing a system model approach. This approach utilizes the derived expression for the input impedance of a network, which simulates the passive properties of neurons, to correlate measured intracellular recordings with the response of network models. In this study, the input impedances of different network configurations and of dentate granule neurons, were derived as a function of the network elements and were validated with computer simulations. The parameters of the system model, which are the values of the network elements, were estimated using an optimization strategy. The system model provides for better estimation of the network elements than the previously described signal model, due to its explicit nature. In contrast, the signal model is an implicit function of the network elements which requires intermediate steps to estimate some of the passive properties. PMID:2765654

D'Aguanno, A; Bardakjian, B L; Carlen, P L

1989-01-01

177

On Passive One-Way Systems  

Microsoft Academic Search

The passivity or positive real condition of passive linear two-terminal-pair networks is introduced. The formulas for thermal noise voltages of these networks are derived by using the Nyquist theorem. A relation between the passivity condition and thermal noise voltages is discussed. From these results, several interesting features of passive one-way systems are derived. For instance, any physically realizable passive one-way

Hideya Gamo

1959-01-01

178

Passive turbulent flamelet propagation  

NASA Technical Reports Server (NTRS)

We analyze results of a premixed constant density flame propagating in three-dimensional turbulence, where a flame model developed by Kerstein, et al. (1988) has been used. Simulations with constant and evolving velocity fields are used, where peculiar results were obtained from the constant velocity field runs. Data from the evolving flow runs with various flame speeds are used to determine two-point correlations of the fluctuating scalar field and implications for flamelet modeling are discussed.

Ashurst, William T.; Ruetsch, G. R.; Lund, T. S.

1994-01-01

179

Microgravity Passive Phase Separator  

NASA Technical Reports Server (NTRS)

A new invention disclosure discusses a structure and process for separating gas from liquids in microgravity. The Microgravity Passive Phase Separator consists of two concentric, pleated, woven stainless- steel screens (25-micrometer nominal pore) with an axial inlet, and an annular outlet between both screens (see figure). Water enters at one end of the center screen at high velocity, eventually passing through the inner screen and out through the annular exit. As gas is introduced into the flow stream, the drag force exerted on the bubble pushes it downstream until flow stagnation or until it reaches an equilibrium point between the surface tension holding bubble to the screen and the drag force. Gas bubbles of a given size will form a front that is moved further down the length of the inner screen with increasing velocity. As more bubbles are added, the front location will remain fixed, but additional bubbles will move to the end of the unit, eventually coming to rest in the large cavity between the unit housing and the outer screen (storage area). Owing to the small size of the pores and the hydrophilic nature of the screen material, gas does not pass through the screen and is retained within the unit for emptying during ground processing. If debris is picked up on the screen, the area closest to the inlet will become clogged, so high-velocity flow will persist farther down the length of the center screen, pushing the bubble front further from the inlet of the inner screen. It is desired to keep the velocity high enough so that, for any bubble size, an area of clean screen exists between the bubbles and the debris. The primary benefits of this innovation are the lack of any need for additional power, strip gas, or location for venting the separated gas. As the unit contains no membrane, the transport fluid will not be lost due to evaporation in the process of gas separation. Separation is performed with relatively low pressure drop based on the large surface area of the separating screen. Additionally, there are no moving parts, and there are no failure modes that involve fluid loss. A patent application has been filed.

Paragano, Matthew; Indoe, William; Darmetko, Jeffrey

2012-01-01

180

Passive Wake Vortex Control  

SciTech Connect

The collapse of the Soviet Union and ending of the Cold War brought about many significant changes in military submarine operations. The enemies that the US Navy faces today and in the future will not likely be superpowers armed with nuclear submarines, but rather smaller, rogue nations employing cheaper diesel/electric submarines with advanced air-independent propulsion systems. Unlike Cold War submarine operations, which occurred in deep-water environments, future submarine conflicts are anticipated to occur in shallow, littoral regions that are complex and noisy. Consequently, non-acoustic signatures will become increasingly important and the submarine stealth technology designed for deep-water operations may not be effective in these environments. One such non-acoustic signature is the surface detection of a submarine's trailing vortex wake. If a submarine runs in a slightly buoyant condition, its diving planes must be inclined at a negative angle of attack to generate sufficient downforce, which keeps the submarine from rising to the surface. As a result, the diving planes produce a pair of counter-rotating trailing vortices that propagate to the water surface. In previous deep-water operations, this was not an issue since the submarines could dive deep enough so that the vortex pair became incoherent before it reached the water surface. However, in shallow, littoral environments, submarines do not have the option of diving deep and, hence, the vortex pair can rise to the surface and leave a distinct signature that might be detectable by synthetic aperture radar. Such detection would jeopardize not only the mission of the submarine, but also the lives of military personnel on board. There has been another attempt to solve this problem and reduce the intensity of trailing vortices in the wakes of military submarines. The research of Quackenbush et al. over the past few years has been directed towards an idea called ''vortex leveraging.'' This active concept works by placing shape memory alloy (SMA) control surfaces on the submarine's diving planes and periodically oscillating them. The modulated control vortices generated by these surfaces interact with the tip vortices on the diving planes, causing an instability to rapidly occur. Though several numerical simulations have been presented, experimental verification does not appear to be available in the open literature. The authors address this problem through a concept called passive wake vortex control (PWVC), which has been demonstrated to rapidly break apart a trailing vortex wake and render it incoherent. PWVC functions by introducing unequal strength, counter-rotating control vortices next to the tip vortices. The presence of these control vortices destabilizes the vortex wake and produces a rapidly growing wake instability.

Ortega, J M

2001-10-18

181

Multivariate Dimensionality Reduction Approaches to Identify Gene-Gene and Gene-Environment Interactions Underlying Multiple Complex Traits  

PubMed Central

The elusive but ubiquitous multifactor interactions represent a stumbling block that urgently needs to be removed in searching for determinants involved in human complex diseases. The dimensionality reduction approaches are a promising tool for this task. Many complex diseases exhibit composite syndromes required to be measured in a cluster of clinical traits with varying correlations and/or are inherently longitudinal in nature (changing over time and measured dynamically at multiple time points). A multivariate approach for detecting interactions is thus greatly needed on the purposes of handling a multifaceted phenotype and longitudinal data, as well as improving statistical power for multiple significance testing via a two-stage testing procedure that involves a multivariate analysis for grouped phenotypes followed by univariate analysis for the phenotypes in the significant group(s). In this article, we propose a multivariate extension of generalized multifactor dimensionality reduction (GMDR) based on multivariate generalized linear, multivariate quasi-likelihood and generalized estimating equations models. Simulations and real data analysis for the cohort from the Study of Addiction: Genetics and Environment are performed to investigate the properties and performance of the proposed method, as compared with the univariate method. The results suggest that the proposed multivariate GMDR substantially boosts statistical power. PMID:25259584

Xu, Hai-Ming; Sun, Xi-Wei; Qi, Ting; Lin, Wan-Yu; Liu, Nianjun; Lou, Xiang-Yang

2014-01-01

182

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

PubMed Central

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

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

2012-01-01

183

All-Passive Nonreciprocal Metasurface  

E-print Network

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.

Mahmoud, Ahmed M; Engheta, Nader

2014-01-01

184

Passivation of high temperature superconductors  

NASA Technical Reports Server (NTRS)

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.

Vasquez, Richard P. (inventor)

1991-01-01

185

Gene-environment interaction between body mass index and transforming growth factor beta 1 (TGF?1) gene in knee and hip osteoarthritis  

PubMed Central

Introduction The objective was to investigate potential gene-environment interaction between body mass index (BMI) and each of eight TGF?1 polymorphisms in knee and hip osteoarthritis (OA). Methods We conducted a case-control study of Caucasian men and women aged 45 to 86 years from Nottingham, United Kingdom (Genetics of OA and Lifestyle (GOAL) study). Cases had clinically severe symptoms and radiographic knee or hip OA; controls had no symptoms and no radiographic knee/hip OA. We used logistic regression to investigate the association of TGF?1 polymorphisms and OA when stratifying by BMI. Knee and hip OA were analyzed separately with adjustment for potential confounders. Additive and multiplicative interactions were examined. Results 2,048 cases (1,042 knee OA, 1,006 hip OA) and 967 controls were studied. For hip OA, the highest risk was in overweight (BMI ?25 kg/m2) individuals with the variant allele of single-nucleotide polymorphism (SNP) rs1800468 (odds ratio (OR) 2.21, 95% confidence interval (CI) 1.55, 3.15). Evaluation of gene-environment interaction indicated significant synergetic interaction (relative excess risk due to interaction (RERI) = 0.93, synergy index (SI) = 4.33) with an attributable proportion due to interaction (AP) of 42% (AP = 0.42; 95% CI 0.16, 0.68). Multiplicative interaction was also significant (OR for interaction (ORINT) = 2.27, P = 0.015). For knee OA, the highest risk was in overweight individuals with homozygous genotype 11 of SNP rs2278422 (OR = 6.95, P <0.001). In contrast, the variant allele indicated slightly lower risks (OR = 4.72, P <0.001), a significant antagonistic interaction (RERI = -2.66, SI = 0.59), AP = -0.56 (95%CI -0.94, -0.17) and a significant multiplicative interaction (ORINT = 0.47, P = 0.013). Conclusion TGF?1 gene polymorphisms interact with being overweight to influence the risk of large joint OA. PMID:23597094

2013-01-01

186

HCI gesture tracking using wearable passive tags  

E-print Network

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 ...

Bainbridge, Rachel M

2010-01-01

187

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

SciTech Connect

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.

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

1988-05-01

188

Influence of meteorological factors on the atmospheric mercury measurement by a novel passive sampler  

NASA Astrophysics Data System (ADS)

In recent years, an incentive for developing simple and cost-effective samplers that are capable of monitoring over an extended period and require nonattendance at remote locations was obvious. Compared to traditional active sampling approaches, passive samplers require no electric power and are more flexible in field deployment, thus they are more appropriate for screening applications and long-term sampling. However, the performance of passive samplers may be influenced by meteorological factors, therefore inducing bias for the result of passive sampling. In this study, the effects of temperature, relative humidity, and wind speed on the performance of a novel passive sampler for gaseous mercury were investigated. The meteorological factors were well controlled in an exposure chamber. The passive samplers were tested in different conditions: temperature ranging from -10 to 35 °C, relative humidity ranging from 25 to 90%, wind speed ranging from 0.5 to 5.0 m s-1. The results showed that temperature and relative humidity had no significant influence on the performance of the passive sampler. However, wind speed was found to have significant impact on the sampling rate of the passive sampler. Wind correction should be considered when making comparisons among samplings with different average wind speeds. In the field application in Beijing and Tibet site, the passively measured data were well correlated with the active measurements.

Guo, Haoli; Lin, Huiming; Zhang, Wei; Deng, Chunyan; Wang, Huanhuan; Zhang, Qianggong; Shen, Yating; Wang, Xuejun

2014-11-01

189

The Passive Aggressive Conflict Cycle  

ERIC Educational Resources Information Center

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…

Whitson, Signe

2013-01-01

190

Orion Passive Thermal Control Overview  

NASA Technical Reports Server (NTRS)

An viewgraph presentation of Orion's passive thermal control system is shown. The topics include: 1) Orion in CxP Hierarchy; 2) General Orion Description/Orientation; 3) Module Descriptions and Images; 4) Orion PTCS Overview; 5) Requirements/Interfaces; 6) Design Reference Missions; 7) Natural Environments; 8) Thermal Models; 9) Challenges/Issues; and 10) Testing

Miller, Stephen W.

2007-01-01

191

Passive cryocooler for microsatellite payload  

Microsoft Academic Search

A passive cryocooler has been developed for the cooling of small payloads to temperatures as low as 145 K. Although designed for a specific electronics experiment on the STRV-1d microsatellite, the device is suitable for a wide range of applications. The cryocooler uses coated surfaces for tailored radiative cooling. Mechanical support between components is provided by fiberglass struts. The measured

Mayes Mullins; Paul J. Thomas; John W. Harron; Philip Duggan; Peter M. Sinclair; S. M. Khanna

1998-01-01

192

Silicon nitride passivation of IC's  

NASA Technical Reports Server (NTRS)

Feasibility study looks at effectiveness of silicon nitride passivation coating against moisture and mobile ions. Coating was tested on CMOS microcircuits. Tests included temperature cycling, high-temperature electrical stress, and temperature and humidity exposure. Report concludes plastic-encapsulated circuits with protective coating exhibit high survival rates; it includes tables summarizing test results and figures that show effects of flexing.

Erickson, J. J.; Gebhart, F. L.; Hall, T. C.; Peters, J. W.

1980-01-01

193

Passive solar, country-style  

SciTech Connect

This article describes a 2170 ft{sup 2} (202 m{sup 2}) custom-designed passive solar home in rural Burlington, North Carolina. The architectural style elegantly combines pleasing aesthetics with practical attention to energy conservation. Included in the article are details of the construction, energy efficient materials and design, energy performance, cost performance.

Miller, B.

1996-07-01

194

Reliability of passive earth pressure  

Microsoft Academic Search

Passive earth pressure calculations in geotechnical analysis are usually performed with the aid of the Rankine or Coulomb theories of earth pressure based on uniform soil properties. These traditional earth pressure theories assume that the soil is uniform. The fact that soils are spatially variable leads to two potential problems in design: do sampled soil properties adequately reflect the effective

D. V. Griffiths; Gordon A. Fenton; Heidi R. Ziemann

2008-01-01

195

Passive solar roof ice melter  

Microsoft Academic Search

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

Deutz

1981-01-01

196

[Passive smoking--active killer].  

PubMed

Although still not perceived in this way, passive smoking is a public health issue of great importance. World Health Organization estimates that as a result of passive exposure to tobacco smoke each year 600,000 people die, of which 165,000 children. There are 33% of men, 35% of women and 40% of children who do not smoke, but are exposed to second hand smoke, and still only 11% of the world population is protected by adequate smoke-free legislation. Scientific literature provides evidence that passive exposure to tobacco smoke can result in numerous adverse health effects: asthma and allergies, respiratory infections and (middle) ear infections, cancers of various localization, accelerated atherosclerosis and cardiovascular diseases, retardation of growth and development in children, and in pregnancy it can lead to congenital anomalies and premature birth as well as lower body weight and length of the child. Certainly, the scariest consequence of all is sudden infant death syndrome, also called "death in the crib". Smoke-free policies have proven their effectiveness, but while implementing the laws, it is necessary to raise public awareness of the hazards of, both active and passive, exposure to tobacco smoke. PMID:24490334

Palavra, Irena Rojni?; Franeli?, Iva Pejnovi?; Milanovi?, Sanja Musi?; Pulji?, Kresimir

2013-01-01

197

Passivation Of High-Temperature Superconductors  

NASA Technical Reports Server (NTRS)

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.

Vasquez, Richard P.

1991-01-01

198

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

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

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

2012-08-01

199

Associations of PI3KR1 and mTOR Polymorphisms with Esophageal Squamous Cell Carcinoma Risk and Gene-Environment Interactions in Eastern Chinese Populations  

PubMed Central

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

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

2015-01-01

200

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

SciTech Connect

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.

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

201

Associations of PI3KR1 and mTOR Polymorphisms with Esophageal Squamous Cell Carcinoma Risk and Gene-Environment Interactions in Eastern Chinese Populations.  

PubMed

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

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

2015-01-01

202

Silicon surface passivation by silicon nitride deposition  

NASA Technical Reports Server (NTRS)

Silicon nitride deposition was studied as a method of passivation for silicon solar cell surfaces. The following three objectives were the thrust of the research: (1) the use of pecvd silicon nitride for passivation of silicon surfaces; (2) measurement techniques for surface recombination velocity; and (3) the importance of surface passivation to high efficiency solar cells.

Olsen, L. C.

1984-01-01

203

Development of Verbal Passive in Williams Syndrome  

ERIC Educational Resources Information Center

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…

Perovic, Alexandra; Wexler, Kenneth

2010-01-01

204

Calibration of Passive Microwave Hybrid Coupler-based Polarimeters  

NASA Technical Reports Server (NTRS)

Passive microwave polarimeters, or polarimetric radiometers, are important tools for Earth remote sensing. They have found utility in ocean surface wind-vector remote sensing and polarization basis rotation systems for compensating instrument or ionospheric induced rotation. The hybrid coupler-based polarimeter is a specific class of polarimeter that utilizes a 180-degree hybrid coupler to affect a correlation between the received vertical and horizontal polarization signals. This type of polarimeter requires at least four calibration states for complete calibration. One state must be a polarized signal, such as the application of a correlated noise source. The phase balance of the noise source directly determines the quality of the calibration.

Piepmeier, J. R.; Kim, E. J.

2003-01-01

205

Using a passive alcohol sensor to detect legally intoxicated drivers.  

PubMed Central

OBJECTIVES. We examined whether a passive alcohol sensor could be used for mass screening of motorists to accurately and quickly detect drivers whose blood alcohol concentration exceeded a variety of levels often established as per se evidence of legal intoxication. METHODS. In a voluntary roadside survey, 1181 late-night drivers in Minnesota were interviewed. Breath measurements were taken with both a passive alcohol sensor and an evidentiary quality portable breath-test device. RESULTS. Measurements could be taken much more easily and quickly with the passive sensor, whose readings correlated very strongly (r = .87) with the evidentiary device. Moreover, for criterion blood alcohol concentration levels ranging from 100 mg/dL to 20 mg/dL, a large proportion of motorists could be accurately identified as being above or below the criterion, with relatively few false-negative or false-positive identifications. CONCLUSIONS. The use of passive alcohol sensors at sobriety checkpoints should allow motorists to be processed very quickly with minimal inconvenience. At the same time, detection of legally intoxicated motorists will probably be substantially increased and the general deterrent value of per se alcohol-impaired driving laws enhanced. PMID:8460734

Foss, R D; Voas, R B; Beirness, D J

1993-01-01

206

Evaluation of Alternate Surface Passivation Methods (U)  

SciTech Connect

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.

Clark, E

2005-05-31

207

Passive cryocooler for microsatellite payload  

NASA Astrophysics Data System (ADS)

A passive cryocooler has been developed for the cooling of small payloads to temperatures as low as 145 K. Although designed for a specific electronics experiment on the STRV-1d microsatellite, the device is suitable for a wide range of applications. The cryocooler uses coated surfaces for tailored radiative cooling. Mechanical support between components is provided by fiberglass struts. The measured end temperature reached is 151 K in a liquid nitrogen dewar which extrapolates to an end temperature of lower than 145 K in space. Thermal vacuum testing and random vibration testing at levels consistent with an Ariane 5 launch have been performed as part of formal qualification for the STRV mission. In this paper, details of the design, analysis, fabrication and testing of the passive cryocooler are presented.

Mullins, Mayes; Thomas, Paul J.; Harron, John W.; Duggan, Philip; Sinclair, Peter M.; Khanna, Shyam M.

1998-11-01

208

Passive Neutron Detection at Borders  

SciTech Connect

Radiation portal monitor systems have been deployed to screen for illicit trafficking of radioactive materials at international border crossings. This report reviews some of the neutron detection requirements and capabilities of passive detection systems used for such applications. Simulations show the effects of cargo materials on neutron spectra, different detector geometries, using a large-array of neutron detectors, and the effects of backgrounds including “ship effect” neutrons.

Kouzes, Richard T.; Siciliano, Edward R.; Ely, James H.; Keller, Paul E.; McConn, Ronald J.

2008-03-01

209

Active and Passive Hybrid Sensor  

NASA Technical Reports Server (NTRS)

A hybrid ocean wind sensor (HOWS) can map ocean vector wind in low to hurricane-level winds, and non-precipitating and precipitating conditions. It can acquire active and passive measurements through a single aperture at two wavelengths, two polarizations, and multiple incidence angles. Its low profile, compact geometry, and low power consumption permits installation on air craft platforms, including high-altitude unmanned aerial vehicles (UAVs).

Carswell, James R.

2010-01-01

210

Monolithically Integrable RF MEMS Passives  

Microsoft Academic Search

This paper presents high performance MEMS passives using fully CMOS compatible, monolithically integrable 3-D RF MEMS processes for RF and microwave applications. The 3-D RF MEMS technology has been developed and investigated as a viable technological option, which can break the limit of the conventional IC technology. We have demonstrated the versatility of the technology by fabricating various 3-D thick-metal

Eun-Chul Park; Yun-Seok Choi; Jun-Bo Yoon; Euisik Yoon

2002-01-01

211

Effect of TNF and LTA polymorphisms on biological markers of response to oxidative stimuli in coal miners: a model of gene-environment interaction  

PubMed Central

Introduction: Interaction between genetic background and oxidative environmental stimuli in the pathogenesis of human lung disease has been largely unexplored. Methods: A prospective epidemiological study was undertaken in 253 coal miners. Intermediate quantitative phenotypes of response to oxidant exposure, including erythrocyte glutathione peroxidase (GSH-Px) and catalase activities, were studied. Oxidant exposures studied were smoking habits and cumulative dust exposure assessed by job history and ambient measures. Disease phenotypes included subclinical computed tomography score at the first survey and x ray profusion grades twice, five years apart, to assess established coal workers' pneumoconiosis (CWP). Miners were genotyped for common functional polymorphisms in the gene for tumour necrosis factor ? (TNF) and lymphotoxin ? (LTA), two proinflammatory cytokines that have been implicated in the pathogenesis of chronic lung diseases. Results: Regarding gene-environment interaction on intermediate phenotypes, results showed interaction of a promoter polymorphism at the –308 position in TNF with occupational exposure on erythrocyte GSH-Px activity with a significant association in those with high exposure (p=0.003), whereas no association was observed among those with low exposure (interaction p=0.06). Regarding gene intermediate phenotype interaction on clinical outcome, results showed an association of CWP prevalence with an NcoI polymorphism in LTA in those with low catalase activity (p=0.05), whereas no association was observed in those with high activity (interaction p=0.03). No other significant association was observed. Conclusion: The results suggest that interactions of genetic background with environmental exposure and intermediate response phenotypes are important components in the pathogenesis of CWP. PMID:12566517

Nadif, R; Jedlicka, A; Mintz, M; Bertrand, J; Kleeberger, S; Kauffmann, F

2003-01-01

212

Tumor-Infiltrating Lymphocyte Grade in Primary Melanomas Is Independently Associated With Melanoma-Specific Survival in the Population-Based Genes, Environment and Melanoma Study  

PubMed Central

Purpose Although most hospital-based studies suggest more favorable survival with tumor-infiltrating lymphocytes (TILs) present in primary melanomas, it is uncertain whether TILs provide prognostic information beyond existing melanoma staging definitions. We addressed the issue in an international population-based study of patients with single and multiple primary melanomas. Patients and Methods On the basis of the Genes, Environment and Melanoma (GEM) study, we conducted follow-up of 2,845 patients diagnosed from 1998 to 2003 with 3,330 invasive primary melanomas centrally reviewed for TIL grade (absent, nonbrisk, or brisk). The odds of TIL grades associated with clinicopathologic features and survival by TIL grade were examined. Results Independent predictors (P < .05) for nonbrisk TIL grade were site, histologic subtype, and Breslow thickness, and for brisk TIL grade, they were age, site, Breslow thickness, and radial growth phase. Nonbrisk and brisk TIL grades were each associated with lower American Joint Committee on Cancer (AJCC) tumor stage compared with TIL absence (Ptrend < .001). Death as a result of melanoma was 30% less with nonbrisk TIL grade (hazard ratio [HR], 0.7; 95% CI, 0.5 to 1.0) and 50% less with brisk TIL grade (HR, 0.5; 95% CI, 0.3 to 0.9) relative to TIL absence, adjusted for age, sex, site, and AJCC tumor stage. Conclusion At the population level, higher TIL grade of primary melanoma is associated with a lower risk of death as a result of melanoma independently of tumor characteristics currently used for AJCC tumor stage. We conclude that TIL grade deserves further prospective investigation to determine whether it should be included in future AJCC staging revisions. PMID:24127443

Thomas, Nancy E.; Busam, Klaus J.; From, Lynn; Kricker, Anne; Armstrong, Bruce K.; Anton-Culver, Hoda; Gruber, Stephen B.; Gallagher, Richard P.; Zanetti, Roberto; Rosso, Stefano; Dwyer, Terence; Venn, Alison; Kanetsky, Peter A.; Groben, Pamela A.; Hao, Honglin; Orlow, Irene; Reiner, Anne S.; Luo, Li; Paine, Susan; Ollila, David W.; Wilcox, Homer; Begg, Colin B.; Berwick, Marianne

2013-01-01

213

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

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

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

214

Evidence of gene-environment interaction for two genes on chromosome 4 and environmental tobacco smoke in controlling the risk of nonsyndromic cleft palate.  

PubMed

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)

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

215

Differences In The Active and Passive Scalar Fluxes In Stably Stratified Turbulence  

NASA Astrophysics Data System (ADS)

Passive and active scalar (i.e., density) fluxes in unsteady stably stratified turbulence are analyzed using the rapid distortion theory (RDT) (e.g., Hanazaki & Hunt, 1996). Analytical solutions of the RDT equations show that the initial conditions, in par- ticular the initial correlations between the passive scalar and the active scalar, are important in determining the difference in the time development between the pas- sive and the active scalar fluxes. If there is initial correlation between the active and passive scalars, the passive scalar flux has the slowly oscillating components of half frequency N (N:Brunt-Vaisala frequency) compared to the usual frequency 2N of the active scalar (density) flux. Analysis in which the effects of diffusion coeeficients (Pr:active scalar, Sc:passive scalar) are considered show that, in the realistic conditions for which Pr<passive scalar fluxes becomes more pronounced at large times. The results helps explaining the recent DNS and ex- perimental results by Kaltenbach, Gerz & Schumann(1994) and Nagata & Komori (2001).

Hanazaki, H.; Miyazaki, T.

216

Dispersion analysis of passive surface-wave noise generated during hydraulic-fracturing operations  

NASA Astrophysics Data System (ADS)

Surface-wave dispersion analysis is useful for estimating near-surface shear-wave velocity models, designing receiver arrays, and suppressing surface waves. Here, we analyze whether passive seismic noise generated during hydraulic-fracturing operations can be used to extract surface-wave dispersion characteristics. Applying seismic interferometry to noise measurements, we extract surface waves by cross-correlating several minutes of passive records; this approach is distinct from previous studies that used hours or days of passive records for cross-correlation. For comparison, we also perform dispersion analysis for an active-source array that has some receivers in common with the passive array. The active and passive data show good agreement in the dispersive character of the fundamental-mode surface-waves. For the higher mode surface waves, however, active and passive data resolve the dispersive properties at different frequency ranges. To demonstrate an application of dispersion analysis, we invert the observed surface-wave dispersion characteristics to determine the near-surface, one-dimensional shear-wave velocity.

Forghani-Arani, Farnoush; Willis, Mark; Snieder, Roel; Haines, Seth S.; Behura, Jyoti; Batzle, Mike; Davidson, Michael

2014-12-01

217

Gap between active and passive solar heating  

SciTech Connect

The gap between active and passive solar could hardly be wider. The reasons for this are discussed and advantages to narrowing the gap are analyzed. Ten years of experience in both active and passive systems are reviewed, including costs, frequent problems, performance prediction, performance modeling, monitoring, and cooling concerns. Trends are analyzed, both for solar space heating and for service water heating. A tendency for the active and passive technologies to be converging is observed. Several recommendations for narrowing the gap are presented.

Balcomb, J.D.

1985-01-01

218

THE PASSIVITY CONTROL FOR TS FUZZY SYSTEMS  

Microsoft Academic Search

In this paper, we propose the notion of strict passivity to T-S fuzzy system and consider the problem of passivity control for a kind of uncertain T-S fuzzy system with time-delay. The su-cient conditions which make the closed-loop system be stable and strictly passive are obtained for the system. The conditions are expressed as linear matrix inequalities (LMIs). So checking

BAOYAN ZHU; JINBAO WANG; YANLI GU

2009-01-01

219

The Future of Passive Solar in Industry  

E-print Network

THE FUTURE OF PASSIVE SOLAR IN INDUSTRY Donald R. WUlfingh9ff, P.E. WUlfinghoff Energy Services, Inc. Wheaton, Maryland ABSTRACT Passive solar is a family of tech niques for the direct use of sunlight for illumination and heating.... Industrial facilities have characteristics which particularly favor the use of these tech niques. This paper examines the applic ability and economic potential of passive solar in the industrial environment, and offers specific suggestions for achieving...

Wulfinghoff, D. R.

220

Effects of isokinetic passive exercise and isometric muscle contraction on passive stiffness.  

PubMed

[Purpose] The purpose of this study was to investigate the effects of isokinetic passive exercise and motion velocity on passive stiffness. In addition, we also discuss the effects of the contraction of agonist and antagonist muscles on passive stiffness. [Subjects] The subjects were 20 healthy men with no bone or joint disease. [Methods] Isokinetic passive exercise and isometric muscle contraction were performed on an isokinetic dynamometer. The angular acceleration measured by the accelerometer was compared before and after each task. [Results] After the passive exercise, the angular acceleration increased in the phase of small damped oscillation. Moreover, the effect was higher at high-speed movement. The angular acceleration was decreased by the contraction of the agonist muscle. Conversely, the angular acceleration was increased by the contraction of the antagonist muscle. [Conclusion] Isokinetic passive exercise reduced passive stiffness. Our results suggest the possibility that passive stiffness is increased by agonist muscle contraction and decreased by antagonist muscle contraction. PMID:24259791

Terada, Shigeru; Miaki, Hiroichi; Uchiyama, Keita; Hayakawa, Shozo; Yamazaki, Toshiaki

2013-10-01

221

Regulation of adult cardiocyte growth: effects of active and passive mechanical loading  

NASA Technical Reports Server (NTRS)

Fluctuations in hemodynamic load have been documented to modulate contractile protein turnover and myofibrillar structure in the heart; however, the relative importance of active and passive loading in regulating adult cardiocyte growth remains unresolved. To address this issue at the cellular level, adult feline cardiocytes were cultured either on Silastic membranes or plastic surfaces. Cardiocyte-laden membranes were stretched 10% of their rest length to enhance passive loading, whereas heart cells cultured on plastic or Silastic were field stimulated at 1 Hz to mimic active loading. Turnover of contractile proteins and structural integrity of the contractile-cytoskeletal apparatus were monitored for periods ranging from 4 to 72 h. Active and passive loading elevated contractile protein synthesis nearly equally (approximately 50%) and promoted the attachment of remodeled myofibrils to vinculin-positive focal contacts and/or costameres during the first 24 h of loading. Thereafter, rates of contractile protein synthesis returned to control values in passively stretched heart cells but remained elevated in field-stimulated cultures. The fractional rate of growth was increased significantly (approximately 8%/day) in electrically paced cells, whereas in passively stretched cardiocytes the growth rate rose only modestly (approximately 2%/day). Changes in the rate of myocyte growth appeared more closely correlated with the development of focal contacts and myofibril remodeling than with changes in myofibrillar protein turnover per se. 2,3-Butanedione monoxime, nifedipine, and, to a lesser extent, ryanodine blocked field-stimulated contractile protein synthesis and myofibrillar remodeling but had no impact on protein turnover or myofibril reassembly in passively loaded cardiocytes. The results of these experiments imply that both active and passive loading stimulate contractile protein turnover and myofibril remodeling, but the generation of active tension accelerates cardiocyte growth to a greater extent than passive loading. Furthermore, pharmacological interventions suggest that unique pathways may mediate these cellular events in actively and passively loaded adult cardiocytes.

Decker, M. L.; Janes, D. M.; Barclay, M. M.; Harger, L.; Decker, R. S.

1997-01-01

222

Photoelectrochemistry of disordered passive films  

SciTech Connect

A theoretical model, which describes subband gap photoexcitation involving localized electronic states, was developed. The escape probability of a charge carrier trapped in a localized state is considered via Poole-Frenkel, direct tunneling, or phonon-assisted tunneling processes, as competing escape mechanisms. Photoelectrochemical experiments were performed on the passive films formed on zirconium and amorphous iron-zirconium alloys and on pure HfO/sub 2/ films and HfO/sub 2/ films implanted with varying concentrations of xenon. These films were found to possess some degree of disorder depending on the substrate, the thickness of the film, and the extent of implantation. The spectral dependence of the photocurrent in all of the films studied is considerably different from what was found for crystalline passive films. The potential dependence of the photocurrent yields Poole-Frenkel behavior. Reverse tunneling processes were also observed at low photon energies and low fields across the film, which is consistent with the theoretical results.

Newark, A.R.

1987-01-01

223

Passive electroreception in aquatic mammals.  

PubMed

Passive electroreception is a sensory modality in many aquatic vertebrates, predominantly fishes. Using passive electroreception, the animal can detect and analyze electric fields in its environment. Most electric fields in the environment are of biogenic origin, often produced by prey items. These electric fields can be relatively strong and can be a highly valuable source of information for a predator, as underlined by the fact that electroreception has evolved multiple times independently. The only mammals that possess electroreception are the platypus (Ornithorhynchus anatinus) and the echidnas (Tachyglossidae) from the monotreme order, and, recently discovered, the Guiana dolphin (Sotalia guianensis) from the cetacean order. Here we review the morphology, function and origin of the electroreceptors in the two aquatic species, the platypus and the Guiana dolphin. The morphology shows certain similarities, also similar to ampullary electroreceptors in fishes, that provide cues for the search for electroreceptors in more vertebrate and invertebrate species. The function of these organs appears to be very similar. Both species search for prey animals in low-visibility conditions or while digging in the substrate, and sensory thresholds are within one order of magnitude. The electroreceptors in both species are innervated by the trigeminal nerve. The origin of the accessory structures, however, is completely different; electroreceptors in the platypus have developed from skin glands, in the Guiana dolphin, from the vibrissal system. PMID:23187861

Czech-Damal, Nicole U; Dehnhardt, Guido; Manger, Paul; Hanke, Wolf

2013-06-01

224

Condensation model for the ESBWR passive condensers  

SciTech Connect

In the General Electric's Economic simplified boiling water reactor (GE-ESBWR) the passive containment cooling system (PCCS) plays a major role in containment pressure control in case of an loss of coolant accident. The PCCS condenser must be able to remove sufficient energy from the reactor containment to prevent containment from exceeding its design pressure following a design basis accident. There are three PCCS condensation modes depending on the containment pressurization due to coolant discharge; complete condensation, cyclic venting and flow through mode. The present work reviews the models and presents model predictive capability along with comparison with existing data from separate effects test. The condensation models in thermal hydraulics code RELAP5 are also assessed to examine its application to various flow modes of condensation. The default model in the code predicts complete condensation well, and basically is Nusselt solution. The UCB model predicts through flow well. None of condensation model in RELAP5 predict complete condensation, cyclic venting, and through flow condensation consistently. New condensation correlations are given that accurately predict all three modes of PCCS condensation. (authors)

Revankar, S. T. [Pohang Univ. of Science and Technology, 400 Central Drive, West Lafayette, IN 47906 (United States); Zhou, W.; Wolf, B.; Oh, S. [Purdue Univ., West Lafayette, IN 47906 (United States)

2012-07-01

225

General Corrosion and Passive Film Stability  

SciTech Connect

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.

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

2005-07-19

226

Passive tracking with sensors of opportunity using passive coherent location  

NASA Astrophysics Data System (ADS)

Passive coherent location (PCL), which uses the commercial signals as illuminators of opportunity, is an emerging technology in air defense systems. The advantages of PCL are low cost, low vulnerability to electronic counter measures, early detection of stealthy targets and low-altitude detection. However, limitations of PCL include lack of control over illuminators, poor bearing accuracy, time-varying sensor parameters and limited observability. In this paper, multiple target tracking using PCL with high bearing error is considered. In this case, the challenge is to handle high nonlinearity due to high measurement error. In this paper, we implement the converted measurement Kalman filter, unscented Kalman filter and particle filter based PHD filter for PCL radar measurements and compare their performances.

Subramaniam, Mahes; Tharmarasa, R.; McDonald, Mike; Kirubarajan, T.

2008-04-01

227

Passive spatial mapping of inertial cavitation during HIFU exposure.  

PubMed

A novel method for mapping inertial cavitation activity during high-intensity focused ultrasound (HIFU) exposure is presented. Inertial cavitation has been previously shown to result in increased heat deposition and to be associated with broadband noise emissions that can be readily monitored using a passive receiver without interference from the main HIFU signal. In the present study, the signals received passively by each of 64 elements on a standard diagnostic array placed coaxially with the HIFU transducer are combined using time exposure acoustics to generate maps of inertially cavitating regions during HIFU exposure of an agar-based tissue-mimicking material. The technique is shown to be effective in localizing single-bubble activity, as well as contiguous and disjoint cavitating regions instigated by creating regions of lower cavitation threshold within the tissue phantom. The cavitation maps obtained experimentally are also found to be in good agreement with computational simulations and theoretical predictions. Unlike B-mode imaging, which requires interleaving with the HIFU pulse, passive array-based mapping of cavitation activity is possible during HIFU exposure. If cavitating regions can be directly correlated to increased tissue damage, this novel cavitation mapping technique could enable real-time HIFU treatment monitoring. PMID:19628450

Gyöngy, Miklós; Coussios, Constantin-C

2010-01-01

228

Passive microwave tags : LDRD 52709, FY04 final report.  

SciTech Connect

This report describes both a general methodology and specific examples of completely passive microwave tags. Surface acoustic wave (SAW) devices were used to make tags for both identification and sensing applications at different frequencies. SAW correlators were optimized for wireless identification, and SAW filters were developed to enable wireless remote sensing of physical properties. Identification tag applications and wireless remote measurement applications are discussed. Significant effort went into optimizing the SAW devices used for this work, and the lessons learned from that effort are reviewed.

Brocato, Robert Wesley

2004-10-01

229

Passive retrieval of Rayleigh waves in disordered elastic media.  

PubMed

When averaged over sources or disorder, cross correlation of diffuse fields yields the Green's function between two passive sensors. This technique is applied to elastic ultrasonic waves in an open scattering slab mimicking seismic waves in the Earth's crust. It appears that the Rayleigh wave reconstruction depends on the scattering properties of the elastic slab. Special attention is paid to the specific role of bulk to Rayleigh wave coupling, which may result in unexpected phenomena, such as a persistent time asymmetry in the diffuse regime. PMID:16383554

Larose, Eric; Derode, Arnaud; Clorennec, Dominique; Margerin, Ludovic; Campillo, Michel

2005-10-01

230

Ambient stability of chemically passivated germanium interfaces  

E-print Network

Ambient stability of chemically passivated germanium interfaces D. Bodlaki, H. Yamamoto, D sulfidation or alkylation of Ge surfaces, SHG appears far less sensitive to H and Cl passivation of germanium surfaces than to silicon surfaces. Investigation of the stability of chemically modified germanium surfaces

Borguet, Eric

231

PASSIVE EARTH PRESSURE DISTRIBUTION UNDER SEISMIC CONDITION  

Microsoft Academic Search

Knowledge of passive resistance and its distribution behind the rigid retaining walls under both static and dynamic conditions are important for designing retaining walls, anchors, foundations etc. In this paper, a method of horizontal slices has been suggested for obtaining seismic passive earth pressure distribution by considering seismic forces in a pseudo-static manner. Only planar rupture surfaces have been considered

Deepankar Choudhury; K. S. Subba Rao; Sanghamitro Ghosh

232

The passivity of natural admittance control implementations  

Microsoft Academic Search

Natural Admittance Control (NAC) has been proposed as a means of implementing responsive force control that is both gentle and rapid while maintaining an end-effector admittance that is passive. Practical implementations, however, must deviate from the ideal NAC formulation, impacting the passivity of the manipulator. Issues arise particularly in the case where NAC is retrofitted to an existing industrial robot

Mark E. Dohring; Wyatt S. Newman

2003-01-01

233

SAW devices as wireless passive sensors  

Microsoft Academic Search

Surface acoustic wave (SAW) radio sensors make it possible to read measurement values from a remote location. The decisive advantage of these SAW sensors lies in their passive operation with no need for a separate power supply, and in the possibility of wireless installation at particularly inaccessible locations. The passive SAW sensors are maintenance free. The physical or chemical properties

L. Reindl; G. Scholl; T. Ostertag; C. C. W. Ruppel; W.-E. Bulst; F. Seifert

1996-01-01

234

Wide band passive repeaters: Design and measurements  

Microsoft Academic Search

The performances of a wideband passive repeater including two broadband antennas and a coaxial line are analyzed both from full-wave electromagnetic simulations and measurement data over 1.6 GHz bandwidth centered at 4 GHz. For carrier signal level lower than the detection threshold, the use of passive repeater can significantly improve the reliability of the wireless link.

A. Ali; A. Coustou; H. Aubert

2009-01-01

235

Cues for Understanding the Passive Voice.  

ERIC Educational Resources Information Center

Two experiments were conducted on the use and combination of three cues that differentiate active from passive verbs: a form of the auxiliary "be," the morphology of the passive participle of the verb, and the case-making preposition "by." In the first experiment, 59 children aged 2.9 to 5.10 years were asked to interpret sentences with one, two,…

Stromswold, Karin; And Others

1985-01-01

236

PsychophysicsIs subliminal learning really passive?  

Microsoft Academic Search

Perceptual learning can occur as a result of exposure to a subliminal stimulus, without the subject having to pay attention and without relevance to the particular task in hand - but is this type of learning purely passive? Here we show that perceptual learning is not passive, but instead results from reinforcement by an independent task. As this learning occurred

Aaron R. Seitz; Takeo Watanabe

2003-01-01

237

Passive Solar Construction--Design and Performance.  

ERIC Educational Resources Information Center

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…

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

238

The German Passive: Analysis and Teaching Technique.  

ERIC Educational Resources Information Center

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)

Griffen, T. D.

1981-01-01

239

Integrated bias removal in passive radar systems  

Microsoft Academic Search

A passive coherent location (PCL) system exploits the ambient FM radio or television signals from powerful local transmitters, which makes it ideal for covert tracking. In a passive radar system, also known as PCL system, a variety of measurements can be used to estimate target states such as direction of arrival (DOA), time difference of arrival (TDOA) or Doppler shift.

M. Subramaniam; K. Punithakumar; M. McDonald; T. Kirubarajan

2008-01-01

240

Passive scalar in a large-scale velocity field I. Kolokolov  

E-print Network

Passive scalar in a large-scale velocity field I. Kolokolov Budker Institute of Nuclear Physics by temperature or by pollutant density. The velocity field is assumed to contain motions from some interval are dealing with the logarithmic case which is substantially sim- pler than cases with power-like correlation

Lebedev, Vladimir

241

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

SciTech Connect

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.

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

1993-02-01

242

Non-destructive assay of spent nuclear fuel using passive neutron Albedo reactivity  

Microsoft Academic Search

Passive Neutron Albedo Reactivity (PNAR) is one of fourteen techniques that has been researched and evaluated to form part of a comprehensive and integrated detection system for the non-destructive assay (NDA) of spent nuclear fuel. PNAR implemented with ³He tubes for neutron detection (PNAR-³He) is the measurement of time correlated neutrons from a spent fuel assembly with and without a

L G Evans; M A Schear; S Croft; S J Tobin; M T Swinhoe; H O Menlove

2010-01-01

243

Simulation of Rate-Related (Dead-Time) Losses In Passive Neutron Multiplicity Counting Systems  

Microsoft Academic Search

Passive Neutron Multiplicity Counting (PNMC) based on Multiplicity Shift Register (MSR) electronics (a form of time correlation analysis) is a widely used non-destructive assay technique for quantifying spontaneously fissile materials such as Pu. At high event rates, dead-time losses perturb the count rates with the Singles, Doubles and Triples being increasingly affected. Without correction these perturbations are a major source

L. G. Evans; P. I. Norman; T. W. Leadbeater; S. Croft; S. Philips

2008-01-01

244

Passive optical lane position monitor  

NASA Astrophysics Data System (ADS)

A laboratory prototype of a passive optical lane position monitor has been designed, built, and tested. The sensor head is simple and consists of two parts: a cylindrical lens, and a position sensitive detector. The amplifier/processing electronics which provides the position signal is compact and lightweight. No complex software or computer is needed. Sensor performance was validated both in the laboratory and in the field. The prototype was tested in sunlight over a range of solar angles from dawn to dusk. It was even tested at night with illumination provided by headlights. The bottom line is that, for such a simple system, the sensor worked quite well. This opens up possibilities for its use as a practical tool in vehicle/highway management.

Geary, Joseph M.

1997-02-01

245

A Passive Magnetic Bearing Flywheel  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

246

Passive phase noise cancellation scheme.  

PubMed

We introduce a new method for reducing phase noise in oscillators, thereby improving their frequency precision. The noise reduction is realized by a passive device consisting of a pair of coupled nonlinear resonating elements that are driven parametrically by the output of a conventional oscillator at a frequency close to the sum of the linear mode frequencies. Above the threshold for parametric instability, the coupled resonators exhibit self-oscillations which arise as a response to the parametric driving, rather than by application of active feedback. We find operating points of the device for which this periodic signal is immune to frequency noise in the driving oscillator, providing a way to clean its phase noise. We present results for the effect of thermal noise to advance a broader understanding of the overall noise sensitivity and the fundamental operating limits. PMID:23004985

Kenig, Eyal; Cross, M C; Lifshitz, Ron; Karabalin, R B; Villanueva, L G; Matheny, M H; Roukes, M L

2012-06-29

247

The influence of active and passive smoking on the cardiorespiratory fitness of adults  

PubMed Central

Background The aim of this study was to analyze the influence of active and passive smoking on cardiorespiratory responses in asymptomatic adults during a sub-maximal-exertion incremental test. Methods The participants (n = 43) were divided into three different groups: active smokers (n = 14; aged 36.5 ± 8 years), passive smokers (n = 14; aged 34.6 ± 11.9 years) and non-smokers (n = 15; aged 30 ± 8.1 years). They all answered the Test for Nicotine Dependence and underwent anthropometric evaluation, spirometry and ergospirometry according to the Bruce Treadmill Protocol. Results VO2max differed statistically between active and non-smokers groups (p < 0.001) and between non-smokers and passive group (p=0.022). However, there was no difference between the passive and active smokers groups (p=0.053). Negative and significant correlations occurred between VO2max and age (r = - 0.401, p = 0.044), percentage of body fat (r = - 0.429, p = 0.011), and waist circumference (WC) (r = - 0.382, p = 0.025). Conclusion VO2max was significantly higher in non-smokers compared to active smokers and passive smokers. However, the VO2max of passive smokers did not differ from active smokers. PMID:25009739

2014-01-01

248

Passive Smoking Impairs Histone Deacetylase-2 in Children With Severe Asthma  

PubMed Central

Background: Parental smoking is known to worsen asthma symptoms in children and to make them refractory to asthma treatment, but the molecular mechanism is unclear. Oxidative stress from tobacco smoke has been reported to impair histone deacetylase-2 (HDAC2) via phosphoinositide-3-kinase (PI3K)/Akt activation and, thus, to reduce corticosteroid sensitivity. The aim of this study was to investigate passive smoking-dependent molecular abnormalities in alveolar macrophages (AMs) by comparing passive smoke-exposed children and non-passive smoke-exposed children with uncontrolled severe asthma. Methods: BAL fluid (BALF) was obtained from 19 children with uncontrolled severe asthma (10 non-passive smoking-exposed subjects and nine passive smoking-exposed subjects), and HDAC2 expression/activity, Akt/HDAC2 phosphorylation levels, and corticosteroid responsiveness in AMs were evaluated. Results: Parental smoking reduced HDAC2 protein expression by 54% and activity by 47%, with concomitant enhancement of phosphorylation of Akt1 and HDAC2. In addition, phosphorylation levels of Akt1 correlated positively with HDAC2 phosphorylation levels and negatively with HDAC2 activity. Furthermore, passive smoke exposure reduced the inhibitory effects of dexamethasone on tumor necrosis factor-?-induced CXCL8 release in AMs. There were relatively higher neutrophil counts and CXCL8 concentrations in BALF and lower Asthma Control Test scores compared with non-passive smoke-exposed children with uncontrolled severe asthma. Conclusions: Passive smoking impairs HDAC2 function via PI3K signaling activation, which could contribute to corticosteroid-insensitive inflammation in children with severe asthma. This novel mechanism will be a treatment target in children with severe asthma and stresses the need for a smoke-free environment for asthmatic children. PMID:24030221

Kobayashi, Yoshiki; Bossley, Cara; Gupta, Atul; Akashi, Kenichi; Tsartsali, Lemonia; Mercado, Nicolas; Barnes, Peter J.; Bush, Andrew

2014-01-01

249

Citric Acid Passivation of Stainless Steel  

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

250

Reliability of reflectance measures in passive filters  

NASA Astrophysics Data System (ADS)

Measurements of optical reflectance in passive filters impregnated with a reactive chemical solution may be transformed to ozone concentrations via a calibration curve and constitute a low cost alternative for environmental monitoring, mainly to estimate human exposure. Given the possibility of errors caused by exposure bias, it is common to consider sets of m filters exposed during a certain period to estimate the latent reflectance on n different sample occasions at a certain location. Mixed models with sample occasions as random effects are useful to analyze data obtained under such setups. The intra-class correlation coefficient of the mean of the m measurements is an indicator of the reliability of the latent reflectance estimates. Our objective is to determine m in order to obtain a pre-specified reliability of the estimates, taking possible outliers into account. To illustrate the procedure, we consider an experiment conducted at the Laboratory of Experimental Air Pollution, University of São Paulo, Brazil (LPAE/FMUSP), where sets of m = 3 filters were exposed during 7 days on n = 9 different occasions at a certain location. The results show that the reliability of the latent reflectance estimates for each occasion obtained under homoskedasticity is km = 0.74. A residual analysis suggests that the within-occasion variance for two of the occasions should be different from the others. A refined model with two within-occasion variance components was considered, yielding km = 0.56 for these occasions and km = 0.87 for the remaining ones. To guarantee that all estimates have a reliability of at least 80% we require measurements on m = 10 filters on each occasion.

Saldiva de André, Carmen Diva; Afonso de André, Paulo; Rocha, Francisco Marcelo; Saldiva, Paulo Hilário Nascimento; Carvalho de Oliveira, Regiani; Singer, Julio M.

2014-08-01

251

Passive fault current limiting device  

DOEpatents

A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment.

Evans, Daniel J. (Wheeling, IL); Cha, Yung S. (Darien, IL)

1999-01-01

252

Passive fault current limiting device  

DOEpatents

A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment. 6 figs.

Evans, D.J.; Cha, Y.S.

1999-04-06

253

PASSIVE DETECTION OF VEHICLE LOADING  

SciTech Connect

The Digital Imaging and Remote Sensing Laboratory (DIRS) at the Rochester Institute of Technology, along with the Savannah River National Laboratory is investigating passive methods to quantify vehicle loading. The research described in this paper investigates multiple vehicle indicators including brake temperature, tire temperature, engine temperature, acceleration and deceleration rates, engine acoustics, suspension response, tire deformation and vibrational response. Our investigation into these variables includes building and implementing a sensing system for data collection as well as multiple full-scale vehicle tests. The sensing system includes; infrared video cameras, triaxial accelerometers, microphones, video cameras and thermocouples. The full scale testing includes both a medium size dump truck and a tractor-trailer truck on closed courses with loads spanning the full range of the vehicle's capacity. Statistical analysis of the collected data is used to determine the effectiveness of each of the indicators for characterizing the weight of a vehicle. The final sensing system will monitor multiple load indicators and combine the results to achieve a more accurate measurement than any of the indicators could provide alone.

Garrett, A.

2012-01-03

254

[Passive euthanasia and living will].  

PubMed

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

Julesz, Máté

2014-07-01

255

Passive detection of vehicle loading  

NASA Astrophysics Data System (ADS)

The Digital Imaging and Remote Sensing Laboratory (DIRS) at the Rochester Institute of Technology, along with the Savannah River National Laboratory is investigating passive methods to quantify vehicle loading. The research described in this paper investigates multiple vehicle indicators including brake temperature, tire temperature, engine temperature, acceleration and deceleration rates, engine acoustics, suspension response, tire deformation and vibrational response. Our investigation into these variables includes building and implementing a sensing system for data collection as well as multiple full-scale vehicle tests. The sensing system includes; infrared video cameras, triaxial accelerometers, microphones, video cameras and thermocouples. The full scale testing includes both a medium size dump truck and a tractor-trailer truck on closed courses with loads spanning the full range of the vehicle's capacity. Statistical analysis of the collected data is used to determine the effectiveness of each of the indicators for characterizing the weight of a vehicle. The final sensing system will monitor multiple load indicators and combine the results to achieve a more accurate measurement than any of the indicators could provide alone.

McKay, Troy R.; Salvaggio, Carl; Faulring, Jason W.; Salvaggio, Philip S.; McKeown, Donald M.; Garrett, Alfred J.; Coleman, David H.; Koffman, Larry D.

2012-01-01

256

Passive environmental temperature control system  

DOEpatents

Passive environmental heating and cooling systems are described, which utilize heat pipes to transmit heat to or from a thermal reservoir. In a solar heating system, a heat pipe is utilized to carry heat from a solar heat absorber plate that receives sunlight, through a thermal insulation barrier, to a heat storage wall, with the outer end of the pipe which is in contact with the solar absorber being lower than the inner end. The inclining of the heat pipe assures that the portion of working fluid, such as Freon, which is in a liquid phase will fall by gravity to the outer end of the pipe, thereby assuring diode action that prevents the reverse transfer of heat from the reservoir to the outside on cool nights. In a cooling system, the outer end of the pipe which connects to a heat dissipator, is higher than the inner end that is coupled to a cold reservoir, to allow heat transfer only out of the reservoir to the heat dissipator, and not in the reverse direction.

Corliss, John M. (Columbus, OH); Stickford, George H. (Columbus, OH)

1981-01-01

257

Passive solar roof ice melter  

SciTech Connect

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.

Deutz, R.T.

1981-09-29

258

Lipid-Based Passivation in Nanofluidics  

PubMed Central

Stretching DNA in nanochannels is a useful tool for direct, visual studies of genomic DNA at the single molecule level. To facilitate the study of the interaction of linear DNA with proteins in nanochannels, we have implemented a highly effective passivation scheme based on lipid bilayers. We demonstrate virtually complete long-term passivation of nanochannel surfaces to a range of relevant reagents, including streptavidin-coated quantum dots, RecA proteins, and RecA–DNA complexes. We show that the performance of the lipid bilayer is significantly better than that of standard bovine serum albumin-based passivation. Finally, we show how the passivated devices allow us to monitor single DNA cleavage events during enzymatic degradation by DNase I. We expect that our approach will open up for detailed, systematic studies of a wide range of protein–DNA interactions with high spatial and temporal resolution. PMID:22432814

2012-01-01

259

Method and structure for passivating semiconductor material  

DOEpatents

A structure for passivating semiconductor material comprises a substrate of crystalline semiconductor material, a relatively thin film of carbon disposed on a surface of the crystalline material, and a layer of hydrogenated amorphous silicon deposited on the carbon film.

Pankove, Jacques I. (Princeton, NJ)

1981-01-01

260

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

USGS Publications Warehouse

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.

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

2004-01-01

261

International comparison of passive solar simulation codes  

SciTech Connect

Two software-software comparisons of passive solar simulation codes have been conducted by the Passive Solar Applications Group of the Committee on the Challenges to Modern Society. These exercises have involved the simulation of hypothetical Trombe wall and direct gain buildings located in Madison, Wisconsin. The countries that have participated in the exercise include Canada, Denmark, France, and the United States. All results available at the time of writing are discussed in this report.

Wray, W.O.

1980-01-01

262

Vertical Diffusivities of Active and Passive Tracers  

NASA Technical Reports Server (NTRS)

The climate models that include a carbon-cycle need the vertical diffusivity of a passive tracer. Since an expression for the latter is not available, it has been common practice to identify it with that of salt. The identification is questionable since T, S are active, not passive tracers. We present the first derivation of the diffusivity of a passive tracer in terms of Ri (Richardson number) and Rq (density ratio, ratio of salinity over temperature z-gradients). The following results have emerged: (a) The passive tracer diffusivity is an algebraic function of Ri, Rq. (b) In doubly stable regimes (DS, partial derivative of T with respect to z > 0, partial derivative of S with respect to z < 0), the passive scalar diffusivity is nearly the same as that of salt/heat for any values of Rq < 0 and Ri > 0. (c) In DC regimes (diffusive convection, partial derivative of T with respect to z < 0, partial derivative of S with respect to z < 0, Rq > 1), the passive scalar diffusivity is larger than that of salt. At Ri = O(1), it can be more than twice as large. (d) In SF regimes (salt fingers, partial derivative of T with respect to z > 0, partial derivative of S with respect to z > 0, Rq < 1), the passive scalar diffusivity is smaller than that of salt. At Ri = O(1), it can be less than half of it. (e) The passive tracer diffusivity predicted at the location of NATRE (North Atlantic Tracer Release Experiment) is discussed. (f) Perhaps the most relevant conclusion is that the common identification of the tracer diffusivity with that of salt is valid only in DS regimes. In the Southern Ocean, where there is the largest CO2 absorption, the dominant regime is diffusive convection discussed in (c) above.

Canuto, V. M.; Cheng, Y.; Howard, A. M.

2010-01-01

263

Nonlinear fixed-order dynamic compensation for passive systems  

Microsoft Academic Search

A general framework for designing nonlinear fixed order (i.e., full- and reduced-order) dynamic passive controllers for passive systems is developed using nonlinear dissipation theory. Specifically, by extending linear passive controller synthesis frameworks a family of globally asymptotically stabilizing nonlinear passive controllers is developed that can serve to enhance system performance and energy dissipation. The proposed approach is applied to the

W. M. Haddad; V.-S. Chellaboina

1997-01-01

264

Passivity and stability of nonlinear systems with Markovian jump parameters  

Microsoft Academic Search

In this paper, we extend the concept of passivity developed for deterministic systems, to stochastic systems with Markov Jump disturbances. We give necessary and sufficient conditions for the system to be passive, and discuss the relationship between positive-real systems and passive systems. The stability properties of the system and the implications of passivity on the stochastic stability of the system

M. D. S. Aliyu; King Fahd

1999-01-01

265

Tracking Passive Sentence Comprehension in Agrammatic Aphasia.  

PubMed

People with agrammatic aphasia often experience greater difficulty comprehending passive compared to active sentences. The Trace Deletion Hypothesis (TDH; Grodzinsky, 2000) proposes that aphasic individuals cannot generate accurate syntactic representations of passive sentences and, hence, use an agent-first processing strategy which leads to at-chance performance. We tested this claim using the eyetracking-while-listening paradigm in order to reveal online processing routines. Ten agrammatic aphasic participants and 10 age-matched controls listened to passive and active sentences and performed a sentence-picture matching task (i.e., selecting between two pictures with reversed thematic roles), while their eye movements were monitored. Control participants' performance was at ceiling, whereas accuracy for the aphasic participants was above chance for active sentences and at chance for passive sentences. Further, for the control participants, the eye movement data showed an initial agent-first processing bias, followed by fixation on the correct picture in the vicinity of the verb in both active and passive sentences. However, the aphasic participants showed no evidence of agent-first processing, counter the predictions of the TDH. In addition, in active sentences, they reliably fixated the correct picture only at sentence offset, reflecting slowed processing. During passive sentence processing, fixations were at chance throughout the sentence, but different patterns were noted for correct and incorrect trials. These results are consistent with the proposal that agrammatic sentence comprehension failure involves lexical processing and/or lexical integration deficits. PMID:22043134

Meyer, Aaron M; Mack, Jennifer E; Thompson, Cynthia K

2012-01-01

266

Discreet passive explosive detection through 2-sided waveguided fluorescence  

DOEpatents

The current invention provides a passive sampling device suitable for collecting and detecting the presence of target analytes. In particular, the passive sampling device is suitable for detecting nitro-aromatic compounds. The current invention further provides a passive sampling device reader suitable for determining the collection of target analytes. Additionally, the current invention provides methods for detecting target analytes using the passive sampling device and the passive sampling device reader.

Harper, Ross James (Stillwater, OK); la Grone, Marcus (Cushing, OK); Fisher, Mark (Stillwater, OK)

2011-10-18

267

Discreet passive explosive detection through 2-sided wave guided fluorescence  

DOEpatents

The current invention provides a passive sampling device suitable for collecting and detecting the presence of target analytes. In particular, the passive sampling device is suitable for detecting nitro-aromatic compounds. The current invention further provides a passive sampling device reader suitable for determining the collection of target analytes. Additionally, the current invention provides methods for detecting target analytes using the passive sampling device and the passive sampling device reader.

Harper, Ross James; la Grone, Marcus; Fisher, Mark

2012-10-16

268

Relationship between shear elastic modulus and passive muscle force: an ex-vivo study.  

PubMed

As muscle is stretched, it reacts with increasing passive resistance. This passive force component is important for normal muscle function. Unfortunately, direct measurement of passive muscle force is still beyond the current state-of-the-art. This study aimed to investigate the feasibility of using Supersonic shear wave elastography (SSWE) to indirectly measure passive muscle force. Sixteen gastronomies pars externus and 16 tibialis anterior muscles were dissected from 10 fresh roaster chickens. For each muscle specimen, the proximal bone-tendon junction was kept intact with its tibia or femur clamped in a fixture. Calibration weights (0-400 g in 25 g per increment) were applied to the distal tendon via a pulley system and muscle elasticity was measured simultaneously using SSWE. The measurements were repeated for 3 cycles. The elasticity-load relationship of each tested muscle for each loading cycle was analyzed by fitting a least-squares regression line to the data. Test-retest reliability was evaluated using intraclass correlation coefficient (ICC). Results demonstrated that the relationships between SSWE elasticity and passive muscle force were highly linear for all the tested muscles with coefficients of determination ranging between 0.971 and 0.999. ICCs were 0.996 and 0.985, respectively, for the slope and y-intercept parameters of the regression lines, indicating excellent reliability. These findings indicate that SSWE, when carefully applied, can be a highly reliable technique for muscle elasticity measurements. The linear relationship between SSWE elasticity and passive muscle force identified in the present study demonstrated that SSWE may be used as an indirect measure of passive muscle force. PMID:23769175

Koo, Terry K; Guo, Jing-Yi; Cohen, Jeffrey H; Parker, Kevin J

2013-08-01

269

Mesoscopics of ultrasound and seismic waves: application to passive imaging  

NASA Astrophysics Data System (ADS)

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).

Larose, É.

2006-05-01

270

Fused performance of passive thermal and active polarimetric EO demining sensor  

NASA Astrophysics Data System (ADS)

The potential for performance improvements through sensor fusion is explored for two electro-optical (EO) imaging sensors: a passive thermal IR camera and an active polarimetric system. Tests of decision-level fusion using a small data set (roughly 60 mine signatures) suggest that a significant performance improvement can be obtained by using an AND fusion approach. The source of this improvement derives from correlation among the sensors. Specifically, the sensors exhibit a strong positive correlation when a mine is present, and a negligible correlation when viewing clutter. The observed improvement is independent of the local ground clutter, but it depends strongly on the decision thresholds used for the individual sensors.

Liao, Wen-Jiao; Baertlein, Brian A.

2002-08-01

271

Passive measurement and interpretation of polarized microwave brightness temperatures  

NASA Technical Reports Server (NTRS)

The goal of this project is to develop satellite-based observational techniques for measuring both oceanic and atmospheric variables using passive polarimetric radiometry. Polarimetric radiometry offers a potential alternative to radar scatterometry in observing global ocean surface wind direction from satellites. Polarimetric radiometry might also provide a means of detecting cell-top ice in convective storms by virtue of the polarizing properties of oriented ice particles, and thus facilitate estimation of the phase of the storm. The project focuses on the development of polarimetric microwave radiometers using digital cross-correlators for obtaining precise measurements of all four Stokes' parameters. As part of the project a unique four-band polarimetric imaging radiometer, the Polar Scanning Radiometer (PSR), is being designed for use on the NASA DC-8 aircraft. In addition to providing an aircraft-based demonstration of digital correlation technology the PSR will significantly enhance the microwave imaging capability of the existing suite of DC-8 instruments. During the first grant year excellent progress has been made in the following areas: (1) demonstrating digital correlation radiometry, (2) fabricating aircraft-qualified correlators for use in the PSR, and (3) modeling observed SSM/I brightness signatures of ocean wind direction.

Gasiewski, A. J.; Kunkee, D. B.; Piepmeier, J. R.

1995-01-01

272

Optical correlation  

NASA Astrophysics Data System (ADS)

Pattern recognition may supplement or replace certain navigational aids on spacecraft in docking or landing activities. The need to correctly identify terrain features remains critical in preparation of autonomous planetary landing. One technique that may solve this problem is optical correlation. Correlation has been successfully demonstrated under ideal conditions; however, noise significantly affects the ability of the correlator to accurately identify input signals. Optical correlation in the presence of noise must be successfully demonstrated before this technology can be incorporated into system design. An optical correlator is designed and constructed using a modified 2f configuration. Liquid crystal televisions (LCTV) are used as the spatial light modulators (SLM) for both the input and filter devices. The filter LCTV is characterized and an operating curve is developed. Determination of this operating curve is critical for reduction of input noise. Correlation of live input with a programmable filter is demonstrated.

Cotariu, Steven S.

1991-12-01

273

Correlation methods  

NASA Technical Reports Server (NTRS)

A method for processing complex radar data with a computer using correlation functions is reviewed. Parameters including data storage, data reduction, and real time operation are addressed. Since complex auto- and cross-correlation functions are calculated and stored, almost no information is lost. These also can be analyzed in terms of the full correlation analysis of the spaced-antenna-drifts technique. The proposed approach therefore appears to be very feasible to suit most Mesosphere-Stratosphere-Troposphere (MST) radar applications.

Rottger, J.

1983-01-01

274

Passivation of fluorinated activated charcoal  

SciTech Connect

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.

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

1997-10-01

275

Passive terahertz imaging for security application  

NASA Astrophysics Data System (ADS)

The passive detection is safe for passengers and operators as no radiation. Therefore, passive terahertz (THz) imaging can be applied to human body security check. Imaging in the THz band offers the unique property of being able to identify object through a range of materials. Therefore passive THz imaging is meaningful for security applications. This attribute has always been of interest to both the civil and military marks with applications. We took advantage of a single THz detector and a trihedral scanning mirror to propose another passive THz beam scanning imaging method. This method overcame the deficiencies of the serious decline in image quality due to the movement of the focused mirror. We exploited a THz scanning mirror with a trihedral scanning mirror and an ellipsoidal mirror to streamline the structure of the system and increase the scanning speed. Then the passive THz beam scanning imaging system was developed based on this method. The parameters were set as follows: the best imaging distance was 1.7m, the image height was 2m, the image width was 1m, the minimum imaging time of per frame was 8s, and the minimum resolution was 4cm. We imaged humans with different objects hidden under their clothes, such as fruit knife, belt buckle, mobile phone, screwdriver, bus cards, keys and other items. All the tested stuffs could be detected and recognized from the image.

Guo, Lan-tao; Deng, Chao; Zhao, Yuan-meng; Zhang, Cun-lin

2013-08-01

276

Contribution of passive smoking to respiratory cancer.  

PubMed Central

This article reviews data from experimental and epidemiologic studies on passive smoking and makes 12 recommendations for further study. The physicochemical nature of passive smoke, the smoke inhaled by nonsmokers, differs significantly from the mainstream smoke inhaled by the active smoker. At present, measurement of urinary cotinine appears to be the best method of assessing exposures to passive smoking. Data indicate that the greater number of lung cancers in nonsmoking women is probably related to environmental tobacco smoke. Exposures in utero and very early in life to passive smoking may be important in relationship to the subsequent development of cancer and need further consideration. The short-term effects of environmental tobacco smoke on the cardiovascular system, especially among high-risk individuals, may be of greater concern than that of cancer and requires further study. Further study of increased risks of lung cancers in relation to environmental tobacco smoke exposure requires larger collaborative studies to identify lung cancer cases among nonsmokers, better delineation of pathology, and more careful selection of controls. In addition, studies of epithelial cells or specific cytology should be undertaken to determine evidence of cellular changes in relation to environmental tobacco smoke exposure. Animal inhalation studies with passive smoke should be initiated with respect to transplacental carcinogenesis, the relationship of sidestream smoke exposure with lung cancer, the induction of tumors in the respiratory tract and other organs, and the differences in the physicochemical natures of sidestream and mainstream smoke. PMID:3830114

Kuller, L H; Garfinkel, L; Correa, P; Haley, N; Hoffmann, D; Preston-Martin, S; Sandler, D

1986-01-01

277

Passivation of iron catalysts for ammonia synthesis  

SciTech Connect

At the present time, the practical interest in passivation of iron ammonia synthesis catalyst results from production of catalyst in reduced form and also from the need for passivation of catalysts during temporary shutdowns of synthesis columns in order to maintain the activity of the catalyst. The spent catalyst also must be passivated prior to offloading, in order to avoid combustion upon contact with air. In all of these cases, the need for passivation of reduced ammonia synthesis catalysts is connected with the pyrophoric character of the iron. It has been established that the pyrophoric character is eliminated after an oxide layer of a specific thickness has been applied to the surface of the iron - i.e., after passivation. To resolve the problems of recovering spent catalyst with controllable depth of oxidation, tests were carried out on low-temperature oxidation of catalysts in the 50-200/sup 0/C temperature interval. This article presents the results of a study of the oxidation of iron on a sample of reduced magnetite and on samples of various industrial ammonia synthesis catalysts (types SA-1, SA-1V and SAMV-5) at 50, 100, 150 and 200/sup 0/C with oxygen from mixtures of oxygen and helium (oxygen concentrations 0.1, 1.0 and 3.0 vol%) under dynamic conditions. 9 references, 3 figures, 4 tables.

Chesnokova, R.V.; Minaev, D.M.; Vasilevich, A.A.; Kuznetsov, L.D.; Alekseev, A.M.; Mishchenko, Sh.Sh.

1984-11-01

278

Initial conditions of a simple passive-dynamic walker  

NASA Astrophysics Data System (ADS)

Walking robots hold great potential for the future of military robotics. Their natural agility in rough, unstructured terrain make them ideal for military applications but their power requirements do not. Passive dynamic walkers offer a potentially low-power solution. This class of legged robots utilize the natural inverted pendular dynamics that humans rely on to locomote. The most basic of these systems uses gravity as its power source and has no control system therefore its stability is heavily reliant on its initial conditions. The VICON Motion Capture System was used to record the motions of Coleman and Ruina's1 TinkertoyWalker. The initial angles and angular velocities of the various trials were extracted from the motion capture data and used as inputs to a multi-body dynamics model of the walker. The model was created to provide insight into passive-dynamic walkers and the interactions between the walker and the ground surface. Several trials were performed to quantify the stability space of the experimental walker and improve the correlation of the dynamics model to the physical robot.

Haueisen, Brooke; Hudas, Greg; Hulbert, Greg; Nebel, Kyle

2006-05-01

279

Hybrid vibration absorber with virtual passive devices  

NASA Astrophysics Data System (ADS)

A vibration control scheme integrating a passive mass-spring resonator and a linear actuator is developed. A control algorithm is devised to convert the actuator into an additional set of virtual mass-spring structure of programmable characteristic frequency. The relative motion between the primary body and the reaction mass is measured, as well as the acceleration of the reaction mass. This hybrid dynamic vibration absorber is capable of neutralizing a harmonic disturbance regardless of the detailed dynamics of the primary structure and other passive elements. Stability analysis leads to a simple, explicit stability criterion. Distribution of the counter-disturbance force between the active and passive devices is analyzed, and the transient performance is also investigated. Real-time experiments as well as numerical simulations are conducted to confirm the effectiveness of the proposed scheme.

Wu, Shang-Teh; Chiu, Yea-Ying; Yeh, Yuan-Chih

2007-01-01

280

The nonlinearity of passive extraocular muscles  

PubMed Central

Passive extraocular muscles (EOMs), like most biological tissues, are hyper-elastic, i.e., their stiffness increases as they are stretched. It has always been assumed, and in a few occasions argued, that this is their only nonlinearity and that it can be ignored in central gaze. However, using novel measurement techniques in anesthetized paralyzed monkeys, we have recently demonstrated that EOMs are characterized by another prominent nonlinearity: the forces induced by sequences of stretches do not sum. Thus, superposition, a central tenet of linear and quasi-linear models, does not hold in passive EOMs. Here, we outline the implications of this finding, especially in light of the common assumption that it is easier for the brain to control a linear than a nonlinear plant. We argue against this common belief: the specific nonlinearity of passive EOMs may actually make it easier for the brain to control the plant than if muscles were linear. PMID:21950971

Quaia, Christian; Ying, Howard S.; Optican, Lance M.

2011-01-01

281

Passive Cooling System for a Vehicle  

DOEpatents

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).

Hendricks, T. J.; Thoensen, T.

2005-11-15

282

Load attenuating passively adaptive wind turbine blade  

DOEpatents

A method and apparatus for improving wind turbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes passively adaptive wind turbine rotors or blades with currently preferred power control features. The apparatus is a composite fiber horizontal axis wind-turbine blade, in which a substantial majority of fibers in the blade skin are inclined at angles of between 15 and 30 degrees to the axis of the blade, to produces passive adaptive aeroelastic tailoring (bend-twist coupling) to alleviate loading without unduly jeopardizing performance.

Veers, Paul S. (Albuquerque, NM); Lobitz, Donald W. (Albuquerque, NM)

2003-01-01

283

Alternative to Nitric Acid Passivation Project Overview  

NASA Technical Reports Server (NTRS)

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.

Lewis, Pattie L.

2013-01-01

284

Passive infrared bullet detection and tracking  

DOEpatents

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. 9 figs.

Karr, T.J.

1997-01-21

285

Passive infrared bullet detection and tracking  

DOEpatents

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.

Karr, Thomas J. (Alamo, CA)

1997-01-01

286

Robust Control of Non-Passive Systems via Passification  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

287

Advances in Inner Magnetosphere Passive and Active Wave Research  

NASA Technical Reports Server (NTRS)

This review identifies a number of the principal research advancements that have occurred over the last five years in the study of electromagnetic (EM) waves in the Earth's inner magnetosphere. The observations used in this study are from the plasma wave instruments and radio sounders on Cluster, IMAGE, Geotail, Wind, Polar, Interball, and others. The data from passive plasma wave instruments have led to a number of advances such as: determining the origin and importance of whistler mode waves in the plasmasphere, discovery of the source of kilometric continuum radiation, mapping AKR source regions with "pinpoint" accuracy, and correlating the AKR source location with dipole tilt angle. Active magnetospheric wave experiments have shown that long range ducted and direct echoes can be used to obtain the density distribution of electrons in the polar cap and along plasmaspheric field lines, providing key information on plasmaspheric filling rates and polar cap outflows.

Green, James L.; Fung, Shing F.

2004-01-01

288

Bacterial turbulence reduction by passive magnetic particle chains  

NASA Astrophysics Data System (ADS)

We report the experimental observation of the bacterial turbulence reduction in dense E. coli suspensions by increasing the coupling of passive particle additives (paramagnetic particles). Applying an external magnetic field induces magnetic dipoles for particles and causes the formation of vertical chain bundles, which are hard for bacterial flows to tilt and break. The larger effective drag coefficient of chains causes slow horizontal motion of chains, which in turn form obstacles to suppress bacterial flows through the strong correlation in coherent bacterial clusters and intercluster interaction. The interruption of the upward energy flow from individual self-propelling bacteria to the larger scale in the bacterial turbulence with multiscaled coherent flow by the chain bundle leads to more severe suppression in the low frequency (wave number) regimes of the power spectra.

Liu, Kuo-An; I, Lin

2013-09-01

289

Passive measurements of mixed-oxide fuel for nuclear nonproliferation  

NASA Astrophysics Data System (ADS)

We present new results on passive measurements and simulations of mixed-oxide fuel-pin assemblies. Potential tools for mixed-oxide fuel pin characterization are discussed for future nuclear-nonproliferation applications. Four EJ-309 liquid scintillation detectors coupled with an accurate pulse timing and digital, offline and optimized pulse-shape discrimination method were used. Measurement analysis included pulse-height distributions to distinguish between purely fission neutron sources and alpha-n plus fission neutrons sources. Time-dependent cross-correlation functions were analyzed to measure the fission neutron contribution to the measured sample's neutron source. The use of Monte Carlo particle transport code MCNPX-PoliMi is discussed in conjunction with the measurements.

Dolan, Jennifer L.; Flaska, Marek; Pozzi, Sara A.; Chichester, David L.

2013-03-01

290

The Construct Validity of Passive-Aggressive Personality Disorder  

PubMed Central

Although Passive Aggressive personality disorder (PAPD) plays an important role in many theories of personality pathology, it was consigned to the appendix of the fourth edition of the DSM. The scientific basis of this decision has been questioned, but several controversies persist regarding PAPD, including its structure, content validity, overlap with other PDs, and relations to validating variables such as personality traits, childhood experiences, and clinically relevant correlates. This study examined these facets of PAPD’s construct validity in a large clinical sample. Results suggest that the construct is unidimensional, internally consistent, and reasonably stable. Furthermore, PAPD appears systematically related to borderline and narcissistic personality disorders, sets of personality traits, and childhood experiences consistent with several theoretical formulations, dysfunction, substance abuse disorders, and history of hospitalizations. Overall, results support the construct validity of PAPD. PMID:19821648

Hopwood, Christopher J.; Morey, Leslie C.; Markowitz, John C.; Pinto, Anthony; Skodol, Andrew E.; Gunderson, John G.; Zanarini, Mary C.; Shea, M. Tracie; Yen, Shirley; McGlashan, Thomas H.; Ansell, Emily B.; Grilo, Carlos M.; Sanislow, Charles A.

2010-01-01

291

The passive diffusion of Leptospira interrogans.  

PubMed

Motivated by recent experimental measurements, the passive diffusion of the bacterium Leptospira interrogans is investigated theoretically. By approximating the cell shape as a straight helix and using the slender-body-theory approximation of Stokesian hydrodynamics, the resistance matrix of Leptospira is first determined numerically. The passive diffusion of the helical cell is then obtained computationally using a Langevin formulation which is sampled in time in a manner consistent with the experimental procedure. Our results are in excellent quantitative agreement with the experimental results with no adjustable parameters. PMID:25426593

Koens, Lyndon; Lauga, Eric

2014-12-01

292

Heterojunction solar cell with passivated emitter surface  

DOEpatents

A high-efficiency heterojunction solar cell is described 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. 1 fig.

Olson, J.M.; Kurtz, S.R.

1994-05-31

293

Dipole transducer enhancement from a passive resonator.  

PubMed

A passive resonator model for enhancing the low frequency performance of dipole transducers is presented using a spherical wave function model. It is shown that because the near field response of a dipole has the same on-axis low frequency dependence as an equivalent monopole, it can effectively excite a nearby monopole passive resonator and do this with enough strength to significantly modify the response of the system. Sample results are presented to demonstrate the performance enhancement and to illustrate the conversion of the dipole beam pattern to a nearly omni-directional beam pattern. PMID:25373949

Butler, John L; Butler, Alexander L; Curtis, Victoria

2014-11-01

294

The passive diffusion of Leptospira interrogans  

NASA Astrophysics Data System (ADS)

Motivated by recent experimental measurements, the passive diffusion of the bacterium Leptospira interrogans is investigated theoretically. By approximating the cell shape as a straight helix and using the slender-body-theory approximation of Stokesian hydrodynamics, the resistance matrix of Leptospira is first determined numerically. The passive diffusion of the helical cell is then obtained computationally using a Langevin formulation which is sampled in time in a manner consistent with the experimental procedure. Our results are in excellent quantitative agreement with the experimental results with no adjustable parameters.

Koens, Lyndon; Lauga, Eric

2014-12-01

295

The Apollo passive seismic experiment  

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

296

Physical Factors Influencing Pleasant Touch during Passive Fingertip Stimulation  

PubMed Central

Objective Tactile explorations with the fingertips provide information regarding the physical properties of surfaces and their relative pleasantness. Previously, we performed an investigation in the active touch domain and linked several surface properties (i.e. frictional force fluctuations and net friction) with their pleasantness levels. The aim of the present study was to investigate physical factors being important for pleasantness perception during passive fingertip stimulation. Specifically we were interested to see whether factors, such as surfaces' topographies or their frictional characteristics could influence pleasantness. Furthermore, we ascertained how the stimulus pleasantness level was impacted by (i) the normal force of stimulus application (FN) and (ii) the stimulus temperature (TS). Methods and Results The right index fingertips of 22 blindfolded participants were stimulated using 27 different stimuli, which varied in average roughness (Ra) and TS. A 4-axis robot moved the stimuli horizontally under participants' fingertips with three levels of FN. The robot was equipped with force sensors, which recorded the FN and friction force (FT) during stimulation. Participants rated each stimulus according to a three-level pleasantness scale, as very pleasant (scored 0), pleasant (scored 1), or unpleasant (scored 2). These ordinal pleasantness ratings were logarithmically transformed into linear and unidimensional pleasantness measures with the Rasch model. Statistical analyses were conducted to investigate a possible link between the stimulus properties (i.e. Ra, FN, FT, and TS) and their respective pleasantness levels. Only the mean Ra and FT values were negatively correlated with pleasantness. No significant correlation was detected between FN or TS and pleasantness. Conclusion Pleasantness perception, resulting from passive fingertip stimulation, seems to be influenced by the surfaces' average roughness levels and average FT occurring during fingertip stimulation. PMID:25000561

Klöcker, Anne; Oddo, Calogero Maria; Camboni, Domenico; Penta, Massimo; Thonnard, Jean-Louis

2014-01-01

297

Passive smoking is associated with lower age at menopause.  

PubMed

Abstract Objective The aim of the study was to investigate the age at menopause in women exposed to passive smoking. Methods The study was designed as a case-control study. The main outcome measure was to compare the age at menopause of women exposed to second-hand smoking to non-exposed women. Results The age at menopause in the group exposed to second-hand smoking was significantly lower than that of women in the non-exposed group (47.0 ± 4.7 vs. 48.1 ± 5.2 years, p = 0.002). In regression analyses, the age at menopause had an inverse correlation with second-hand smoking, and a positive correlation with the mother's age at menopause. We further stratified women according to their smoking status. Women exposed to second-hand smoking who had never smoked had a significantly lower age at menopause than the non-exposed women only when the duration of exposure exceeded 20 years (46.6 ± 5.6 vs. 48.4 ± 3.7 years, p = 0.008). Furthermore, women who had never smoked and who were exposed to ? 10 cigarettes per day had a significantly lower mean age at menopause than non-exposed women who had never smoked. These differences were not observed among women who had ever smoked. Conclusions Our findings suggest that earlier age at menopause should be added to the negative effects of passive smoking, in addition to increased risks for overall, cardiovascular and cancer mortality as well as increased risk for osteoporosis. PMID:25032840

Ertunc, D; Tok, E C; Aytan, H; Gozukara, Y M

2015-02-01

298

Universality in passively advected hydrodynamic fields: the case of a passive vector with pressure  

E-print Network

Universality of statistical properties of passive quantities advected by turbulent velocity fields at changing the passive forcing mechanism is discussed. In particular, we concentrate on the statistical properties of an hydrodynamic system with pressure. We present theoretical arguments and preliminary numerical results which show that the fluxes of passive vector field and of the velocity field have the same scaling behavior. By exploiting such a property, we propose a way to compute the anomalous exponents of three dimensional turbulent velocity fields. Our findings are in agreement within 5% with experimental values of the anomalous exponents.

R. Benzi; L. Biferale; F. Toschi

2001-03-30

299

Measurement of Human Serum IgE and IgA by Reverse Passive Antiglobulin Haemagglutination  

Microsoft Academic Search

Serum IgE levels can be measured by reverse passive antiglobulin haemagglutination (RPAH) of trypsin-treated human or sheep red cells coupled to sheep IgG anti-human IgE by chromic chloride. The results show a high correlation with those obtained by the radioactive single radial immunodiffusion method. Interfering anti-sheep IgG factors can be easily removed by absorption with small amounts of whole sheep

M. L. Scott; Margaret J. Thornley; R. R. A. Coombs; A. R. Bradwell

1981-01-01

300

Correlation Correlogram  

E-print Network

Network Correlation Neural Oscillator Correlogram CrossHair cell Cochlear Filtering Signal neural oscillators representing a single perceptual stream are synchronised, and are desynchronised from oscillator synchronisation. Model Overview Oscillator Array · Segment formation: excitatory and inhibitory

Wrigley, Stuart

301

Death Anxiety and Voluntary Passive Euthanasia: Influences of Proximity to Death and Experiences with Death in Important Other Persons.  

ERIC Educational Resources Information Center

Identified five sources of death anxiety. Significant relationships were observed between each source and experimental factors. The relationship between death anxiety and attitude toward voluntary passive euthanasia was explored, and a significant correlation was noted among elderly persons. Results were consistent with an idiographic orientation…

Devins, Gerald M.

1979-01-01

302

Comparison of passive microwave and modeled estimates of total watershed SWE in the continental United States  

NASA Astrophysics Data System (ADS)

the U.S., a dedicated system of snow measurement stations and snowpack modeling products is available to estimate the snow water equivalent (SWE) throughout the winter season. In other regions of the world that depend on snowmelt for water resources, snow data can be scarce, and these regions are vulnerable to drought or flood conditions. Even in the U.S., water resource management is hampered by limited snow data in certain regions, as evident by the 2011 Missouri Basin flooding due in large part to the significant Plains snowpack. Satellite data could potentially provide important information in under-sampled areas. This study compared the daily AMSR-E and SSM/I SWE products over nine winter seasons to spatially distributed, modeled output SNODAS summed over 2100 watersheds in the conterminous U.S. Results show large areas where the passive microwave retrievals are highly correlated to the SNODAS data, particularly in the northern Great Plains and southern Rocky Mountain regions. However, the passive microwave SWE is significantly lower than SNODAS in heavily forested areas, and regions that typically receive a deep snowpack. The best correlations are associated with basins in which maximum annual SWE is less than 200 mm, and forest fraction is less than 20%. Even in many watersheds with poor correlations between the passive microwave data and SNODAS maximum annual SWE values, the overall pattern of accumulation and ablation did show good agreement and therefore may provide useful hydrologic information on melt timing and season length.

Vuyovich, Carrie M.; Jacobs, Jennifer M.; Daly, Steven F.

2014-11-01

303

Intermittency and anomalous scaling of passive scalars in any space dimension  

NASA Astrophysics Data System (ADS)

We establish exact inequalities for the structure-function scaling exponents of a passively advected scalar in both the inertial-convective and viscous-convective ranges. These inequalities involve the scaling exponents of the velocity structure functions and, in a refined form, an intermittency exponent of the convective-range scalar flux. They are valid for three-dimensional Navier-Stokes turbulence and satisfied within errors by present experimental data. The inequalities also hold for any ``synthetic'' turbulent velocity statistics with a finite correlation in time. We show that for time-correlation exponents of the velocity smaller than the ``local turnover'' exponent, the scalar spectral exponent is strictly less than that in Kraichnan's [Phys. Rev. Lett. 72, 1016 (1994); Phys. Fluids 11, 945 (1968); J. Fluid Mech. 64, 737 (1974); 62, 305 (1974)] soluble ``rapid-change'' model with velocity ? correlated in time. Our results include as a special case an exponent inequality derived previously by Constantin and Procaccia [Nonlinearity 7, 1045 (1994)], but with a more direct proof. The inequalities in their simplest form follow from a Kolmogorov-type relation for the turbulent passive scalar valid in each space dimension d. Our improved inequalities are based upon a rigorous version of the refined similarity hypothesis for passive scalars. These are compared with the relations implied by ``fusion rules'' hypothesized for scalar gradients.

Eyink, Gregory L.

1996-08-01

304

Passive acoustic tomography of the ocean using arrays of unknown shape  

NASA Astrophysics Data System (ADS)

It was recently established that ocean acoustic tomography based on an inversion of ray travel times can be implemented without use of any dedicated sound sources by cross-correlating the ambient noise recorded on two line arrays, the shapes of which are known. In contrast to active tomography, the amount of useful information from noise interferometry is proportional to the product of the numbers of receivers in the two arrays. In our study based on the 2D and 3D numerical experiments, we examine a hypothesis concerning the feasibility of simultaneous performance of a passive ray tomography and passive positioning of arrays through cross-correlation of ambient or shipping noise. The numerical experiments are conducted under conditions close to those of a field experiment on passive ocean tomography. It is demonstrated that, when using arrays of 20-40 hydrophones, the sound velocity profile and the array shape can be found from noise correlation to an accuracy adequate for oceanological and acoustic applications.

Goncharov, V. V.; Chepurin, Yu. A.; Godin, O. A.

2013-03-01

305

21 CFR 888.3025 - Passive tendon prosthesis.  

...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...

2014-04-01

306

21 CFR 888.3025 - Passive tendon prosthesis.  

Code of Federal Regulations, 2012 CFR

...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...

2012-04-01

307

Surface passivation process of compound semiconductor material using UV photosulfidation  

DOEpatents

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.

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

1995-01-01

308

Active and passive coping strategies in chronic pain patients  

E-print Network

and the Vanderbilt Pain Management Inventory were both found to be psychometfically sound measures of these dimensions of active and passive coping. Passive coping was found to be strongly related to psychological distress. In contrast, active coping was inversely...

Snow-Turek, Andrea Lynn

2012-06-07

309

48 CFR 252.211-7006 - Passive Radio Frequency Identification.  

Code of Federal Regulations, 2011 CFR

...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...

2011-10-01

310

48 CFR 252.211-7006 - Passive Radio Frequency Identification.  

Code of Federal Regulations, 2012 CFR

...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...

2012-10-01

311

48 CFR 252.211-7006 - Passive Radio Frequency Identification.  

Code of Federal Regulations, 2013 CFR

...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...

2013-10-01

312

48 CFR 252.211-7006 - Passive Radio Frequency Identification.  

...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...

2014-10-01

313

Prediction techniques for passive systems' probability of failure  

E-print Network

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. ...

Cavalieri d'Oro, Edoardo

2007-01-01

314

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

PubMed

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

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

1995-03-01

315

Closure Approximations for Passive Scalar Turbulence  

E-print Network

Closure Approximations for Passive Scalar Turbulence: A Comparative Study on an Exactly Solvable running head: "Closure approximations: A Comparative Study" Corresponding author: Peter Kramer 301 Amos Sciences, New York University, New York, NY 1 #12;Abstract Some standard closure approximations used

Kramer, Peter

316

Closure Approximations for Passive Scalar Turbulence  

E-print Network

Closure Approximations for Passive Scalar Turbulence: A Comparative Study on an Exactly Solvable Suggested running head: "Closure approximations: A Comparative Study" Corresponding author: Peter Kramer 301 Sciences, New York University, New York, NY 1 #12;Abstract Some standard closure approximations used

Van Den Eijnden, Eric

317

Studies on a passive electromagnetic damper  

Microsoft Academic Search

The passive electromagnetic damper has the same configuration as that of the electromagnetic bearing, but no sensors and no closed loop control are needed. Its robustness and no-contact structure are its great advantages. When the rotor vibrates, the electromagnetic field intensity in the air gap is altered, then fluctuating currents in the damper coils and eddy currents inside the surface

ZHENG Shui-ying; PAN Xiao-hong; MA Zhen-fei

318

Passivity analysis for flexible multilink space manipulators  

Microsoft Academic Search

The important input-output property of passivity is explored for a general flexible space manipulator with chain topology. The manipulator is assumed to consist of rigid and\\/or flexible links interconnected via revolute joints, and a free rigid spacecraft and cantilevered payload are modeled at the base and tip, respectively. Actuation on the spacecraft and torques at the joints serve as control

Christopher J. Damaren

1995-01-01

319

Sunspot Time Series: Passive and Active Intervals  

NASA Astrophysics Data System (ADS)

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.

Zi?ba, S.; Nieckarz, Z.

2014-07-01

320

Passivity Analysis of Uncertain Singularly Perturbed Systems  

Microsoft Academic Search

This brief addresses the asymptotic stability and passivity of uncertain singularly perturbed systems. Based on the Lyapunov stability theory and a singular-system approach, some sufficient conditions in terms of linear matrix inequalities are derived. Three numerical examples are presented to demonstrate the effectiveness of the proposed theoretical results.

Yanbo Gao; Guoping Lu; Zhiming Wang

2010-01-01

321

Passive damping in EDS maglev systems.  

SciTech Connect

There continues to be strong interest in the subjects of damping and drag forces associated with electrodynamic suspension (EDS) systems. While electromagnetic drag forces resist the forward motion of a vehicle and therefore consume energy, damping forces control, at least in part, the response of the vehicle to disturbances. Ideally, one would like to reduce the drag forces as much as possible while retaining adequate damping forces to insure dynamic stability and satisfactory ride quality. These two goals turn out to be difficult to achieve in practice. It is well known that maglev systems tend to be intrinsically under damped. Consequently it is often necessary in a practical system design to enhance the damping passively or actively. For reasons of cost and simplicity, it is desirable to rely as much as possible on passive damping mechanisms. In this paper, rough estimates are made of the passive damping and drag forces caused by various mechanisms in EDS systems. No attention will be given to active control systems or secondary suspension systems which are obvious ways to augment passive damping mechanisms if the latter prove to be inadequate.

Rote, D. M.

2002-05-03

322

Mennonite Nursing Home passive solar demonstration  

SciTech Connect

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)

Not Available

1984-03-01

323

Submerged passively-safe power plant  

SciTech Connect

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.

Herring, J.S.

1991-12-31

324

An HPSG analysis of Arabic passive  

Microsoft Academic Search

In spite of being a successful syntactic theory in many respects, head-driven phrase structure grammar (HPSG) has inadequate coverage for morphological constructions, especially for nonconcatenative morphology, which is prominent in the Semitic languages such as Arabic, Hebrew etc. Among various syntactic and semantic phenomenon, passive constructions draws attention of many researchers in theoretical linguistics due to their diversity. Arabic exhibits

M. S. I. Bhuyan; R. Ahmed

2008-01-01

325

Load attenuating passively adaptive wind turbine blade  

Microsoft Academic Search

A method and apparatus for improving wind turbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes

Paul S. Veers; Donald W. Lobitz

2003-01-01

326

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...

327

Jitter performance in ethernet passive optical networks  

Microsoft Academic Search

Ethernet passive optical networks (EPONs) have emerged as one of the most promising access network technologies. Propelled by rapid price declines in fiber optics and Ethernet components, these architectures combine the latest in optical and electronic advances and are poised to become the dominant means of delivering gigabit broadband connectivity to homes over a unified single platform. As this technology

Abdallah Shami; Xiaofeng Bai; Chadi M. Assi; Nasir Ghani

2005-01-01

328

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...

329

Multiple object identification with passive RFID tags  

Microsoft Academic Search

We investigate the applicability of passive RFID systems to the task of identifying multiple tagged objects simultaneously, assuming that the number of tags is not known in advance. We present a combinatorial model of the communication mechanism between the reader device and the tags, and use this model to derive the optimal parameter setting for the reading process, based on

Harald Vogt

2002-01-01

330

Efficient Object Identification with Passive RFID Tags  

Microsoft Academic Search

Radio frequency identification systems with passive tags are power- ful tools for object identification. However, if multiple tags are to be identified simultaneously, messages from the tags can collide and cancel each other out. Therefore, multiple read cycles have to be performed in order to achieve a high recognition rate. For a typical stochastic anti-collision scheme, we show how to

Harald Vogt

2002-01-01

331

Distributed Passive Monitoring in Sensor Networks  

Microsoft Academic Search

Operation and control in wireless sensor networks (WSN) demands for new concepts and strategies such as dis- tributed behavior control and self-organization. During the de- velopment and operation, the verification of the implemented algorithms is usually hard to discover. Monitoring techniques are required for this purpose. We present a concept for passive monitoring of WSN. Our hierarchical architecture allows a

Falko Dressler; Rodrigo Nebel; Abdalkarim Awad

332

Abnormalities in passive movement: diagrammatic representation.  

PubMed

"Geography would be incomprehensible without maps. They've reduced a tremendous muddle of facts into something you can read at a glance. Now I suspect [passive movement] is fundamentally no more difficult than geography. Except that it's about things in motion. If only somebody would invent a dynamic map." C. P. Snow(2.) PMID:25025660

Hickling, J; Maitland, G D

1970-03-01

333

Passive ranging using a single IR sensor  

SciTech Connect

As current defense system architectures change and downsize there is a need to accomplish more with each sensors capability. Desert Storm`s missile to aircraft and missile to missile engagements elevated the need to better cope with early and stealthy assessment of the adversaries location while providing minimal compromise to the operator. The use of stealth vehicles introduces a requirement to deploy sensors that silently assess tactical and theater issues [battle damage assessment (BDA) and theater missile defense (TMD)] without preengagement detection. IR sensor system development and high speed, parallel, distributed processing make practical the implementation of compact passive ranging packages aboard satellites and aircraft. Here, single IR Sensor Passive Ranging from an observer to a target embedded in the atmosphere exploits the effect of atmospheric attenuation of the signal. By judicious choice of wavebands the range and altitude to a target can be determined passively with a single observer. This result will be shown to be relatively insensitive to assumed atmospheric models or precise source spectral content. A detailed closed-form solution relating range (and altitude) to observed target intensities will be presented. Previous studies of this type have required either detailed knowledge of the source spectra or spectral resolution of individual rotational lines. The single sensor passive ranging methodology requires no such detailed information.

Jeffrey, W. [Inst. for Defense Analyses, Alexandria, VA (United States); Gobel, R.W. [Analytic Services, Inc., Arlington, VA (United States); Draper, J.S. [KTAADN, Inc., Newton, MA (United States)

1994-12-31

334

Passive and active Reconfigurable antenna design  

E-print Network

Passive and active Reconfigurable antenna design Doctoral course ­ Ulm, Germany - October 8-12 2012 antennas in Cognitive radio applications, Combining Photonics and RF to produce more versatile of Reconfiguration Devices and Technology (Semiconductors ­ MEMS) - Integration of devices into antennas (including

Pfeifer, Holger

335

NSTX Passive Structure and Vertical Stability  

NASA Astrophysics Data System (ADS)

The National Spherical Torus Experiment (NSTX) is a low aspect ratio device with a plasma current of 1.0 MA. Low aspect ratio plasmas are known to have better n=0 axisymmetric stability than higher aspect ratio configurations. Vertical stability is critically dependent on the passive structure that surrounds the plasma. NSTX has a SS outer vacuum vessel, an Inconel center casing, and Cu passive plates. The passive plates in NSTX consist of sectors each 30 degrees in toroidal extent which are connected electrically to the vacuum vessel wall via SS supports. If these Cu sectors are connected to form a saddle loop with a single toroidal break axisymmetric stability analysis predicted acceptable growth times in the range of 100-300 ms. 3D electromagnetic calculations however, indicated that the currents did not remain in the Cu plates but were shared with the vacuum vessel through the SS supports. This produced an unacceptable field perturbation near the toroidal break. To avoid this nonaxisymmetric perturbation, the direct connections between all passive plate sectors were disconnected. This leads to a decrease in the vertical growth times that approachs a factor of 10-15. Analysis will be presented to show what plasma configurations may be produced with NSTX feedback control in the present machine configuration.

Kessel, C. E.; Bialek, J.

1999-11-01

336

Passive Smoking in the Workplace: Selected Issues.  

ERIC Educational Resources Information Center

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…

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

337

Design tools for passive solar applications  

SciTech Connect

Examples of passive solar design tools are given, categorized as either evaluation tools or guidance tools. A trend toward microcomputer-based tools is noted; however, these are usually developed for use by engineers rather than architects. The need for more instructive tools targeted specifically to designers is emphasized.

Balcomb, J.D.

1986-04-01

338

Passive Supporters of Terrorism and Phase Transitions  

E-print Network

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.

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

2010-01-01

339

PCM Passive Cooling System Containing Active Subsystems  

NASA Technical Reports Server (NTRS)

A multistage system has been proposed for cooling a circulating fluid that is subject to intermittent intense heating. The system would be both flexible and redundant in that it could operate in a basic passive mode, either sequentially or simultaneously with operation of a first, active cooling subsystem, and either sequentially or simultaneously with a second cooling subsystem that could be active, passive, or a combination of both. This flexibility and redundancy, in combination with the passive nature of at least one of the modes of operation, would make the system more reliable, relative to a conventional cooling system. The system would include a tube-in-shell heat exchanger, within which the space between the tubes would be filled with a phase-change material (PCM). The circulating hot fluid would flow along the tubes in the heat exchanger. In the basic passive mode of operation, heat would be conducted from the hot fluid into the PCM, wherein the heat would be stored temporarily by virtue of the phase change.

Blanding, David E.; Bass, David I.

2005-01-01

340

Submerged passively-safe power plant  

DOEpatents

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.

Herring, J.S.

1993-09-21

341

Submerged passively-safe power plant  

DOEpatents

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.

Herring, J. Stephen (Idaho Falls, ID)

1993-01-01

342

Photodetectors with passive thermal radiation control  

DOEpatents

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.

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

2001-10-02

343

Passive peak pressure and temperature gages  

Microsoft Academic Search

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

Staller

1989-01-01

344

Passive Pressure Determination by Method of Slices  

Microsoft Academic Search

A method of slices satisfying all the conditions of statical equilibrium has been developed to deal with the problem of determination of passive earth pressure over a retaining wall in sand. A method similar to that of Morgenstern and Price, which was used to solve the stability of slopes, has been followed. The earth pressure coefficients with the proposed methodology

Jyant Kumar; Kanakapura S. Subba Rao

1997-01-01

345

Models for the evolution of passive margins  

E-print Network

3 Models for the evolution of passive margins A.B. Watts Department of Earth Sciences, University and continen- tal breakup. According to his model, the lithosphere is heated during rifting which causes initial level, thereby forming a marginal depression for continental-derived sediments to infill. Sleep

Watts, A. B. "Tony"

346

Passive Smoking, Asthma and Allergy in Children  

Microsoft Academic Search

Despite the recent campaigns to eliminate smoking and hinder the detrimental effects of passive smoking (PS), actual smoking rates still increase worldwide. Several physiological systems, with the respiratory being the primary, are disrupted by PS and progressively deteriorate through chronic exposures. This is of particular importance in children, given that respiratory complications during childhood can be transferred to adulthood, lead

Giorgos S. Metsios; Andreas D. Flouris; Yiannis Koutedakis

2009-01-01

347

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

NASA Astrophysics Data System (ADS)

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.

Harto, Andang Widi

2012-06-01

348

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

SciTech Connect

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.

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

2012-06-06

349

26 CFR 1.469-3T - Passive activity credit (temporary).  

Code of Federal Regulations, 2010 CFR

...passive activity deductions (B's net passive income) is $2,000...50 (C) Taxable income minus net passive income 86,050 (D...to passive activities for 1988 is zero. Although B's net operating loss for the taxable...

2010-04-01

350

26 CFR 1.469-3T - Passive activity credit (temporary).  

...passive activity deductions (B's net passive income) is $2,000...50 (C) Taxable income minus net passive income 86,050 (D...to passive activities for 1988 is zero. Although B's net operating loss for the taxable...

2014-04-01

351

26 CFR 1.469-3T - Passive activity credit (temporary).  

Code of Federal Regulations, 2011 CFR

...passive activity deductions (B's net passive income) is $2,000...50 (C) Taxable income minus net passive income 86,050 (D...to passive activities for 1988 is zero. Although B's net operating loss for the taxable...

2011-04-01

352

26 CFR 1.469-3T - Passive activity credit (temporary).  

Code of Federal Regulations, 2013 CFR

...passive activity deductions (B's net passive income) is $2,000...50 (C) Taxable income minus net passive income 86,050 (D...to passive activities for 1988 is zero. Although B's net operating loss for the taxable...

2013-04-01

353

26 CFR 1.469-3T - Passive activity credit (temporary).  

Code of Federal Regulations, 2012 CFR

...passive activity deductions (B's net passive income) is $2,000...50 (C) Taxable income minus net passive income 86,050 (D...to passive activities for 1988 is zero. Although B's net operating loss for the taxable...

2012-04-01

354

Passive synthesis of the antenna aperture for satellite systems  

NASA Astrophysics Data System (ADS)

The possibility of passive synthesis of the antenna aperture for satellite systems of monitoring ground-based radio radiation sources is discussed. Experimental data on the inverse passive synthesis on the Space-Earth paths are presented for reception of GPS navigation satellite radiation. The data confirm the possibility of developing the passive synthesized aperture radar and interference phase signal processing.

Shumskii, P. O.; Meshcheryakov, A. A.; Sharygin, G. S.

2012-08-01

355

Passivity and feedback design of nonlinear stochastic systems  

Microsoft Academic Search

In this paper, the problem of feedback equivalence to a passive system is studied for a class of nonlinear stochastic systems. Based on a nonlinear stochastic KYP lemma, we investigate the relationship between a passive system and the corresponding zero-output system, which sustains a different result from the deterministic case. Following the stochastic passivity theory, a sufficient condition is given

Zhongwei Lin; Yan Lin

2009-01-01

356

On preserving passivity in sampled-data linear systems  

Microsoft Academic Search

Passivity is a well known phenomenon in several engineering areas. Due to its interesting properties, it is used in several areas of control engineering. Generally, this property is lost under direct discretization. In this work a new methodology which allows preserving continuous-time passivity is presented. This methodology is based on choosing a proper output, which preserves the passivity structure, while

Ramon Costa-Castello; Enric Fossas

2006-01-01

357

Utilizing Passive Ventilation to Complement HVAC Systems in Enclosed Buildings  

E-print Network

Utilizing Passive Ventilation to Complement HVAC Systems in Enclosed Buildings Tom Rogg REU Student are important considerations in building design. Incorporation of a combination of passive ventilation systems of the National Science Foundation. Research Objectives · To provide proof of concept that a passive ventilation

Mountziaris, T. J.

358

Low-Cost Manufacturable Microchannel Systems for Passive  

E-print Network

Low-Cost Manufacturable Microchannel Systems for Passive PEM Water Management IIPS Number 16910 LowLow--CostCost ManufacturableManufacturable Microchannel Systems for PassiveMicrochannel Systems for Passive PEM Water microchannels, cools incoming cathode exhaust to close approach (~10C) to outgoing cathode air Capillary forces

359

Pressure measurement from the RADAR interrogation of passive sensors  

Microsoft Academic Search

The pressure applied to passive sensors modifies their radar echo magnitude. From the FMCW radar interrogation of such passive sensors the pressure can then been remotely measured. The first experimental results presented here demonstrate the feasibility of the wireless measurement of physical quantities from radar echo measurement of passive sensors.

F. Chebila; M. M. Jatlaoui; P. Pons; H. Aubert

2010-01-01

360

Temperature Sensor Tag for Passive UHF RFID Systems  

E-print Network

Temperature Sensor Tag for Passive UHF RFID Systems Juha Virtanen, Leena Ukkonen, Toni Björninen sensor tag for passive UHF RFID systems and discusses a method to perform measurements in practice be constructed with a commercial passive UHF RFID IC. The temperature sensor tag's measurement range spans from

Elsherbeni, Atef Z.

361

Synchronization of unified chaotic system based on passive control  

NASA Astrophysics Data System (ADS)

Chaos synchronization in the unified chaotic system was discussed using passive control. On the basis of the property of the passive system, the passive controller is designed and synchronization of two identical unified chaotic systems with different initial conditions is realized. Simulation results for two Lorenz, two Lü and two Chen chaotic systems are provided to show the effectiveness of the proposed synchronization method.

Wang, Faqiang; Liu, Chongxin

2007-01-01

362

Passive in Danish, English, and German Stefan Muller  

E-print Network

Passive in Danish, English, and German Stefan M¨uller Freie Universit¨at Berlin Bjarne �rsnes Freie://csli-publications.stanford.edu/HPSG/2013 M¨uller, Stefan, & �rsnes, Bjarne. (2013). Passive in Danish, English, and Ger- man. In Stefan M in the passive in Danish, English, and German can be accounted for. The three languages differ along

363

PLASTIC-BASED PATTERN TRANSFER PROCESS FOR RF MEMS PASSIVES  

Microsoft Academic Search

A plastic-based pattern transfer process to integrate microelectromechanical systems (MEMS) passive components onto microelectronics substrate is reported . A group of radio frequency (RF) MEMS passive components such as spiral inductors was fabricated on a substrate as a master mold. Reverse images of the RF MEMS passive components master mold were replicated in polydimethylsiloxane (PDMS). An RF circuit emulating substrate

Sang Won Park; Kabseog Kim; Jeong-Bong Lee; Wendell Alan Davis

364

26 CFR 1.469-2 - Passive activity loss.  

Code of Federal Regulations, 2010 CFR

...taxpayer must allocate the passive activity gross income (determined...f) from the item and the passive activity deductions reasonably...by any drilling, logging, seismic testing, or other activities...469-1T(e)(4) as not from a passive activity. In the...

2010-04-01

365

Compressibility Effects on the Passive Scalar Flux Within Homogeneous Turbulence  

NASA Technical Reports Server (NTRS)

Compressibility effects on turbulent transport of a passive scalar are studied within homogeneous turbulence using a kinematic decomposition of the velocity field into solenoidal and dilatational parts. It is found that the dilatational velocity does not produce a passive scalar flux, and that all of the passive scalar flux is due to the solenoidal velocity.

Blaisdell, G. A.; Mansour, N. N.; Reynolds, W. C.

1994-01-01

366

Characterization and comparison of three passive air samplers for persistent organic pollutants.  

PubMed

The accumulation of persistent organic pollutants by three passive sampling media--semipermeable membrane devices (SPMDs), polyurethane foam (PUF) disks, and an organic-rich soil--was investigated. The media were exposed to contaminated indoor air over a period of 450 days, and concentrations in the air and in the media were monitored for individual polychlorinated biphenyl (PCB) congeners and polychlorinated naphthalene homologue groups. Uptake was initially linear and governed by the surface area of the sampler and the boundary layer airside mass transfer coefficient (MTC). Mean values of the MTC were 0.13, 0.11, and 0.26 cm s-1 for SPMD, PUF, and soil, respectively. As the study progressed, equilibrium was established between ambient air and the passive sampling media for the lower molecular weight PCB congeners. This information was used to calculate passive sampler-air partition coefficients, KPSM-A. These were correlated to the octanol-air partition coefficient, and the resulting regressions were used to predict KPSM-A for the full suite of PCBs. Information on MTC, KPSM-A, surface area, and effective thickness of each sampler was used to estimate times to equilibrium for each medium. These ranged from tens of days for the lower molecular weight congeners to tens of years for the higher molecular weight PCBs. Expressions were also developed to relate the amount of chemical accumulated by the passive sampling media to average ambient air concentrations over the integration period of the sample. PMID:12380087

Shoeib, Mahiba; Harner, Tom

2002-10-01

367

Phosphorous passivation of the SiO 2/4H-SiC interface  

NASA Astrophysics Data System (ADS)

We describe experimental and theoretical studies to determine the effects of phosphorous as a passivating agent for the SiO 2/4H-SiC interface. Annealing in a P 2O 5 ambient converts the SiO 2 layer to PSG (phosphosilicate glass) which is known to be a polar material. Higher mobility (approximately twice the value of 30-40 cm 2/V s obtained using nitrogen introduced with an anneal in nitric oxide) and lower threshold voltage are compatible with a lower interface defect density. Trap density, current-voltage and bias-temperature stress (BTS) measurements for MOS capacitors are also discussed. The BTS measurements point to the possibility of an unstable MOSFET threshold voltage caused by PSG polarization charge at the O-S interface. Theoretical considerations suggest that threefold carbon atoms at the interface can be passivated by phosphorous which leads to a lower interface trap density and a higher effective mobility for electrons in the channel. The roles of phosphorous in the passivation of correlated carbon dangling bonds, for SiC counter-doping, for interface band-tail state suppression, for Na-like impurity band formation and for substrate trap passivation are also discussed briefly.

Sharma, Y. K.; Ahyi, A. C.; Issacs-Smith, T.; Shen, X.; Pantelides, S. T.; Zhu, X.; Feldman, L. C.; Rozen, J.; Williams, J. R.

2012-02-01

368

Elbow spasticity during passive stretch-reflex: clinical evaluation using a wearable sensor system  

PubMed Central

Background Spasticity is a prevalent chronic condition among persons with upper motor neuron syndrome that significantly impacts function and can be costly to treat. Clinical assessment is most often performed with passive stretch-reflex tests and graded on a scale, such as the Modified Ashworth Scale (MAS). However, these scales are limited in sensitivity and are highly subjective. This paper shows that a simple wearable sensor system (angle sensor and 2-channel EMG) worn during a stretch-reflex assessment can be used to more objectively quantify spasticity in a clinical setting. Methods A wearable sensor system consisting of a fibre-optic goniometer and 2-channel electromyography (EMG) was used to capture data during administration of the passive stretch-reflex test for elbow flexor and extensor spasticity. A kinematic model of unrestricted passive joint motion was used to extract metrics from the kinematic and EMG data to represent the intensity of the involuntary reflex. Relationships between the biometric results and clinical measures (MAS, isometric muscle strength and passive range of motion) were explored. Results Preliminary results based on nine patients with varying degrees of flexor and extensor spasticity showed that kinematic and EMG derived metrics were strongly correlated with one another, were correlated positively (and significantly) with clinical MAS, and negatively correlated (though mostly non-significant) with isometric muscle strength. Conclusions We conclude that a wearable sensor system used in conjunction with a simple kinematic model can capture clinically relevant features of elbow spasticity during stretch-reflex testing in a clinical environment. PMID:23782931

2013-01-01

369

PHACT: Parallel HOG and Correlation Tracking  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

370

Modeling of Passive Forces of Machine Tool Covers  

NASA Astrophysics Data System (ADS)

The passive forces acting against the drive force are phenomena that influence dynamical properties and precision of linear axes equipped with feed drives. Covers are one of important sources of passive forces in machine tools. The paper describes virtual evaluation of cover passive forces using the cover complex model. The model is able to compute interaction between flexible cover segments and sealing wiper. The result is deformation of cover segments and wipers which is used together with measured friction coefficient for computation of cover total passive force. This resulting passive force is dependent on cover position. Comparison of computational results and measurement on the real cover is presented in the paper.

Kolar, Petr; Hudec, Jan; Sulitka, Matej

371

Correlative tomography.  

PubMed

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

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

372

Correlative Tomography  

NASA Astrophysics Data System (ADS)

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.

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

373

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

PubMed

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

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

2014-01-21

374

Implications of passive safety based on historical industrial experience  

SciTech Connect

In the past decade, there have been multiple proposals for applying different technologies to achieve passively safe light water reactors (LWRs). A key question for all such concepts is, ''What are the gains in safety, costs, and reliability for passive safety systems.'' Using several types of historical data, estimates have been made of gains from passive safety and operating systems, which are independent of technology. Proposals for passive safety in reactors usually have three characteristics: (1) Passive systems with no moving mechanical parts, (2) systems with far fewer components and (3) more stringent design criteria for safety-related and process systems. Each characteristic reduces the potential for an accident and may increase plant reliability. This paper addresses gains from items (1) and (2). Passive systems often allow adoption of more rigorous design criteria which would be either impossible or economically unfeasible for active systems. This important characteristic of passive safety systems cannot be easily addressed using historical industrial experience.

Forsberg, C.W.

1988-01-01

375

Evaluation of Alternate Stainless Steel Surface Passivation Methods  

SciTech Connect

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.

Clark, Elliot A.

2005-05-31

376

Passive appendages generate drift through symmetry breaking.  

PubMed

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

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

2014-01-01

377

Integration of Passive Components for Spacecraft Avionics  

NASA Astrophysics Data System (ADS)

The NASA roadmap outlining future deep space missions to Europa and other outer planetary destinations calls for continued reductions in the mass and volume of the spacecraft avionics. Spacecraft power electronics, including the power switches and converters, remain difficult to miniaturize due to the need for large numbers of discrete passive components such as resistors, capacitors, inductors and transformers. As part of the System-on-a-chip program at the Center for Integrated Space Microsystems and at the University of Arkansas, we are working to develop integrated or embedded passive components geared specifically for use in power management and distribution (PMAD) in future avionics over the next five to ten years. This will not only enable a scaling down of the power subsystems, but will make possible new architectures such as "distributed" PMAD. Additional information is contained in the original extended abstract.

Brandon, E. J.; Wesseling, E.; White, V.; Lieneweg, U.; Mojarradi, M.; Ulrich, R.; Wasef, M.; Mantooth, A.

2001-01-01

378

Passive load control for large wind turbines.  

SciTech Connect

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.

Ashwill, Thomas D.

2010-05-01

379

Germanium detector passivated with hydrogenated amorphous germanium  

DOEpatents

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.

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

1986-01-01

380

Passive appendages generate drift through symmetry breaking  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

381

Turbulent drag reduction by passive mechanisms  

NASA Astrophysics Data System (ADS)

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).

Sirovich, L.; Karlsson, S.

1997-08-01

382

Passive infrared ice detection for helicopter applications  

NASA Technical Reports Server (NTRS)

A technique is proposed to remotely detect rotor icing on helicopters by using passive IR thermometry to detect the warming caused by latent heat release as supercooled water freezes. During icing, the ice accretion region will be warmer than the uniced trailing edge, resulting in a characteristic chordwise temperature profile. Preliminary tests were conducted on a static model in the NASA Icing Research Tunnel for a variety of wet (glaze) and dry (rime) ice conditions. The chordwise temperature profiles were confirmed by observation with an IR thermal video system and thermocouple observations. The IR observations were consistent with predictions of the LEWICE ice accretion code, which was used to extrapolate the observations to rotor icing conditions. Based on the static observations, the passive IR ice detection technique appears promising; however, further testing or rotating blades is required.

Dershowitz, Adam L.; Hansman, R. John, Jr.

1990-01-01

383

Structural Damage Detection Using Virtual Passive Controllers  

NASA Technical Reports Server (NTRS)

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.

Lew, Jiann-Shiun; Juang, Jer-Nan

2001-01-01

384

Passive heat transfer means for nuclear reactors  

DOEpatents

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.

Burelbach, James P. (Glen Ellyn, IL)

1984-01-01

385

Passive Pressure Determination by Method of Slices  

NASA Astrophysics Data System (ADS)

A method of slices satisfying all the conditions of statical equilibrium has been developed to deal with the problem of determination of passive earth pressure over a retaining wall in sand. A method similar to that of Morgenstern and Price, which was used to solve the stability of slopes, has been followed. The earth pressure coefficients with the proposed methodology have been computed for a vertical retaining wall for both positive and negative wall friction angle. Also examined is the variation of the interslice shear force between the retaining wall and the Rankine Passive boundary. Due to complete satisfaction of the equilibrium conditions, the method generates exactly the same earth pressure coefficients as computed by using Terzaghi's overall limit equilibrium approach.

Kumar, Jyant; Subba Rao, Kanakapura S.

1997-05-01

386

Dynamics of Passive and Active Particles in the Cell Nucleus  

PubMed Central

Inspite of being embedded in a dense meshwork of nuclear chromatin, gene loci and large nuclear components are highly dynamic at 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 ( and 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 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 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 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

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

2012-01-01

387

Passive Endwall Treatments for Enhancing Stability  

NASA Technical Reports Server (NTRS)

These lecture notes were presented at the von Karman Institutes lecture series on Advances in Axial Compressor Aerodynamics, May 2006. They provide a fairly extensive overview of what's been learned from numerous investigations of various passive casing endwall technologies that have been proposed for alleviating the stall limiting physics associated with the compressor endwall flow field. The lecture notes are organized to give an appreciation for the inventiveness and understanding of the earliest compressor technologists and to provide a coherent thread of understanding that has arisen out of the early investigations. As such the lecture notes begin with a historical overview of casing treatments from their infancy through the earliest proposed concepts involving blowing, suction and flow recirculation. A summary of lessons learned from these early investigations is provided at the end of this section. The lecture notes then provide a somewhat more in-depth overview of recent advancements in the development of passive casing treatments from the late 1990's through 2006, including advancements in understanding the flow mechanism of circumferential groove casing treatments, and the development of discrete tip injection and self-recirculating casing treatments. At the conclusion of the lecture notes a final summary of lessons learned throughout the history of the development of passive casing treatments is provided. Finally, a list of future needs is given. It is hoped that these lecture notes will be a useful reference for future research endeavors to improve our understanding of the fluid physics of passive casing treatments and how they act to enhance compressor stability, and that they will perhaps provide a springboard for future research activities in this area of interest

Hathaway, Michael D.

2007-01-01

388

Studies on a passive electromagnetic damper  

Microsoft Academic Search

The passive electromagnetic damper has the same configuration as that of the electromagnetic bearing, but no sensors and no\\u000a closed loop control are needed. Its robustness and no-contact structure are its great advantages. When the rotor vibrates,\\u000a the electromagnetic field intensity in the air gap is altered, then fluctuating currents in the damper coils and eddy currents\\u000a inside the surface

Shui-ying Zheng; Xiao-hong Pan; Zhen-fei Ma

2006-01-01

389

Passively cooled direct drive wind turbine  

DOEpatents

A wind turbine is provided that passively cools an electrical generator. The wind turbine includes a plurality of fins arranged peripherally around a generator house. Each of the fins being oriented at an angle greater than zero degrees to allow parallel flow of air over the fin. The fin is further tapered to allow a constant portion of the fin to extend beyond the air stream boundary layer. Turbulence initiators on the nose cone further enhance heat transfer at the fins.

Costin, Daniel P. (Chelsea, VT)

2008-03-18

390

Passive modal damping with piezoelectric shunts  

SciTech Connect

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.

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

2001-01-01

391

Cooperative passive-solar commercial retrofit  

Microsoft Academic Search

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'

W. T. Brown

1982-01-01

392

Instrumenting hybrid passive\\/active solar systems  

Microsoft Academic Search

A set of recommendations are provided for instrumenting and reporting the performance of hybrid passive\\/active solar heating systems. The discussion centers on the entire system\\/subsystem\\/site combination and attempts to remove some of the uncertainties in providing sufficient data for adequate performance evaluations of such systems. The major subject of this paper concerns solar heating systems utilizing massive thermal storage that

W. W. Youngblood; J. C. Gray

1978-01-01

393

The Acquisition of Passives in Serbian  

ERIC Educational Resources Information Center

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),…

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

2014-01-01

394

Electrochemical passivation of ordered NiAl  

SciTech Connect

The passivity and electrochemical behavior of single crystalline, ordered NiAl intermetallic compound in buffered solutions of pH 2, 7, and 12.5 was compared to that of polycrystalline Ni and Al. NiAl exhibited improved passivity compared to Ni at a pH of 2, and improved passivity compared to Al at pH 12.5. Water oxidation and reduction were enhanced on NiAl compared to Al, suggesting the presence of a more conductive or catalytic oxide film. Al{sub 2}O{sub 3} was preferentially formed (>60 atom % of all oxidized Ni and Al species) throughout the interior of oxide films formed anodically at each pH as well as within the air-formed oxide grown at room temperature. However, the oxide surface layers exhibited a tendency toward nearly equal presence of oxidized Ni{sup +2}, especially as the pH was increased to 7 and 12.5. Therefore, Al{sub 2}O{sub 3} formation was favored, but not exclusively, during electrochemical passivation. In contrast, little or no Ni{sup +2} (as NiO or NiAl{sub 2}O{sub 4}) has been reported after high temperature oxidation of NiAl. The composition of the electrochemically grown oxide is influenced by the specific oxide solubility and kinetic formation/dissolution rates at the oxide/solution interface as well as by the free energy of formation of the oxides.

Lillard, R.S.; Scully, J.R. [Univ. of Virginia, Charlottesville, VA (United States)

1998-06-01

395

Eighth national passive solar conference. Final report  

SciTech Connect

The Eighth National Passive Solar Conference was held near Santa Fe, New Mexico at the Glorieta Conference Center on September 5 to 11, 1983. Nearly 900 people from all across the nation and the world attended the conference. Close to 200 technical papers were presented, 50 solar product exhibits were available; 34 poster sessions were presented; 16 solar workshops were conducted; 10 renowned solar individuals participated in rendezvous sessions; 7 major addresses were delivered; 5 solar home tours were conducted; 2 emerging architecture sessions were held which included 21 separate presentations; and commercial product presentations were given for the first time ever at a national passive solar conference. Peter van Dresser of Santa Fe received the prestigious Passive Solar Pioneer Award, posthumously, from the American Solar Energy Society and Benjamin T. Buck Rogers of Embudo received the prestigious Peter van Dresser Award from the New Mexico Solar Energy Association. This report reviews conference organization, attendance, finances, conference evaluation form results, and includes press coverage samples, selected conference photos courtesy of Marshall Tyler, and a summary with recommendations for future conferences. The Appendices included conference press releases and a report by the New Mexico Solar Industry Development Corporation on exhibits management.

Owen, A.; Zee, R.

1983-12-01

396

Active and passive SWIR imaging polarimetry  

NASA Astrophysics Data System (ADS)

Efforts to understand the potential for polarization information to improve our target acquisition capability have been extended from the mid and long wave IR regions into the short wave IR. A passive, complete rotating- retarder Stokes imaging polarimeter has been developed, calibrated, and field tested. A review of the calibration and some example phenomenology will be presented, including temporal variation of target polarization signatures. Spectral investigation of targets and backgrounds in the SWIR band have been promising. For daytime use, passive polarization imaging could provide additional information for improved detection or identification. The passive polarization imaging effort in the SWIR forms one half of an active polarization agile 1.54 micrometers imaging system. In this system, the polarization of radiation from an eye-safe 1.54 micrometers laser is controlled so that a target or background can be illuminated with a known polarization. Analysis of the reflected beam allows calculation of the Mueller Matrices will hopefully lead to better target-to-background discrimination. This Active Mueller Imaging Ellipsometer has been calibrated, and initial imagery of targets has been collected.

Miller, Miranda A.; Blumer, Robert V.; Howe, James D.

2002-01-01

397

Natural fracture characterization using passive seismic illumination  

SciTech Connect

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.

Nihei, K.T.

2003-01-08

398

Stable surface passivation process for compound semiconductors  

DOEpatents

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.

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

2001-01-01

399

Rapid efficient coding of correlated complex acoustic properties  

PubMed Central

Natural sounds are complex, typically changing along multiple acoustic dimensions that covary in accord with physical laws governing sound-producing sources. We report that, after passive exposure to novel complex sounds, highly correlated features initially collapse onto a single perceptual dimension, capturing covariance at the expense of unitary stimulus dimensions. Discriminability of sounds respecting the correlation is maintained, but is temporarily lost for sounds orthogonal or oblique to experienced covariation. Following extended experience, perception of variance not captured by the correlation is restored, but weighted only in proportion to total experienced covariance. A Hebbian neural network model captures some aspects of listener performance; an anti-Hebbian model captures none; but, a principal components analysis model captures the full pattern of results. Predictions from the principal components analysis model also match evolving listener performance in two discrimination tasks absent passive listening. These demonstrations of adaptation to correlated attributes provide direct behavioral evidence for efficient coding. PMID:21098293

Stilp, Christian E.; Rogers, Timothy T.; Kluender, Keith R.

2010-01-01

400

Tracking marine mammals using passive acoustics  

NASA Astrophysics Data System (ADS)

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.

Nosal, Eva-Marie

2007-12-01

401

Cavity length dependence of mode beating in passively Q-switched Nd-solid state lasers  

NASA Astrophysics Data System (ADS)

The temporal intensity profile of pulse(s) from passively Q-switched and passively Q-switched mode locked (QSML) solid-state lasers is known to be dependent on cavity length. In this work, the pulse width, modulation depth, and beat frequencies of a Nd:Cr:GSGG laser using a Cr+4:YAG passive Q-switch are investigated as function cavity length. Measured temporal widths are linearly correlated with cavity length but generally 3-5 ns larger than theoretical predictions. Some cavity lengths exhibit pulse profiles with no modulation while other lengths exhibit complete amplitude modulation. The observed beat frequencies at certain cavity lengths cannot be accounted for with passively QSML models in which the pulse train repetition rate is ?RT-1, ?RT= round-trip time. They can be explained, however, by including coupled cavity mode-locking effects. A theoretical model developed for a two section coupled cavity semiconductor laser is adapted to a solid-state laser to interpret measured beat frequencies. We also numerically evaluate the temporal criterion required to achieve temporally smooth Q-switched pulses, versus cavity length and pump rate. We show that in flash lamp pumped systems, the difference in buildup time between longitudinal modes is largely dependent on the pump rate. In applications where short pulse delay is important, the pumping rate may limit the ability to achieve temporally smooth pulses in passively Q-switched lasers. Simulations support trends in experimental data. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Zameroski, Nathan D.; Wanke, Michael; Bossert, David

2013-03-01

402

Electrochemical characterization of anode passivation mechanisms in copper electrorefining  

NASA Astrophysics Data System (ADS)

Anode passivation can decrease productivity and quality while increasing costs in modern copper electrorefineries. This investigation utilized electrochemical techniques to characterize the passivation behavior of anode samples from ten different operating companies. It is believed that this collection of anodes is the most diverse set ever to be assembled to study the effect of anode composition on passivation. Chronopotentiometry was the main electrochemical technique, employing a current density of 3820 A m-2. From statistical analysis of the passivation characteristics, increasing selenium, tellurium, silver, lead and nickel were shown to accelerate passivation. Arsenic was the only anode impurity that inhibited passivation. Oxygen was shown to accelerate passivation when increased from 500 to 1500 ppm, but further increases did not adversely affect passivation. Nine electrolyte variables were also examined. Increasing the copper, sulfuric acid or sulfate concentration of the electrolyte accelerated passivation. Arsenic in the electrolyte had no effect on passivation. Chloride and optimal concentrations of thiourea and glue delayed passivation. Linear sweep voltammetry, cyclic voltammetry, and impedance spectroscopy provided complementary information. Analysis of the electrochemical results led to the development of a unified passivation mechanism. Anode passivation results from the formation of inhibiting films. Careful examination of the potential details, especially those found in the oscillations just prior to passivation, demonstrated the importance of slimes, copper sulfate and copper oxide. Slimes confine dissolution to their pores and inhibit diffusion. This can lead to copper sulfate precipitation, which blocks more of the surface area. Copper oxide forms because of the resulting increase in potential at the interface between the copper sulfate and anode. Ultimate passivation occurs when the anode potential is high enough to stabilize the oxide film in the bulk electrolyte. The effect of anode impurities or electrolyte concentrations can be related to the formation of one of these films. Reactions occurring after passivation have also been examined. Post-passivation reactions are believed to include silver dissolution, transformation of lead sulfate to lead oxide, and oxygen evolution. Following the sharp potential increase caused by the passivation, silver that has accumulated on the anode surface will dissolve into the electrolyte at a potential between 1.0 and 1.3 V. After the silver has dissolved, the potential increases again at which point the oxidation of lead sulfate to lead oxide occurs. The formation of lead oxide provides a surface with a lower oxygen evolution overpotential. The presence of kupferglimmer also results in a stable lower oxygen evolution potential occurring at approximately 2.0 V.

Moats, Michael Scott

403

Passive solar progress: a simplified guide to the 3rd national passive solar conference  

SciTech Connect

Some of the concepts and practices that have come to be known as passive solar heating and cooling are introduced, and a current picture of the field is presented. Much of the material presented is derived from papers given at the 3rd National Passive Solar Conference held in San Jose, California in January 1979 and sponsored by the US Department of Energy. Extracts and data from these papers have been integrated in the text with explanatory and descriptive material. In this way, it is attempted to present technical information in an introductory context. Topics include design considerations, passive and hybrid systems and applications, sizing methods and performance prediction, and implementation issues. A glossary is included. (WHK)

Miller, H.; Howell, Y.; Richards, D.

1980-10-01

404

Electronic Structure of Passivated Au38\\(SCH3\\)24 Nanocrystal  

NASA Astrophysics Data System (ADS)

Energetics, electronic structure, charging, and capacitive properties of bare and thiol-passivated Au38 gold nanocrystals were investigated via density-functional calculations. In the energy-optimized passivated nanocrystal, comprised of a truncated-octahedral face-centered-cubic Au38 core coated by a monolayer of 24 methylthiol \\(SCH3\\) molecules, we find interfacial charge transfer of about 2e from the outermost gold atoms to the sulfur atoms. The estimated effective capacitance is 0.084 aF, correlating well with recent electrochemical measurements. Charging takes place within the molecular layer. Molecular adsorption of dimethyl-disulfide is found to be energetically unfavorable for a gold cluster of this size.

Häkkinen, H.; Barnett, R. N.; Landman, U.

1999-04-01

405

Molecular arrangement investigation of copper phthalocyanine grown on hydrogen passivated Si(1 1 1) surfaces  

NASA Astrophysics Data System (ADS)

Chemical, electronic and structural properties of ultra thin films of copper phthalocyanine (CuPc) grown on hydrogen passivated silicon (1 1 1) surfaces were investigated in situ by X-ray photoelectron spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), X-ray photoelectron diffraction (XPD) and electron diffraction (LEED). The early stages of copper phthalocyanine adsorption (1-2) were characterized by the saturation of surface defects and by a flat lying disposition on the surface. Upon further CuPc coverage, the passivation of Si surfaces resulted in the molecule taking a standing position in films. The molecular packing deduced from these studies appears very close to the one in the bulk ? phase of CuPc. The work function of the films was found to be decreasing during the growth and was correlated with the molecular orientation.

Arbi, I.; Ben Hamada, B.; Souissi, A.; Menzli, S.; Ben Azzouz, C.; Laribi, A.; Akremi, A.; Chefi, C.

2014-06-01

406

In situ XANES detection of Cr(VI) in the passive film on Fe-26Cr  

SciTech Connect

The passive film on sputter deposited thin film Fe-26Cr electrodes has been examined using the technique of in situ X-ray absorption near edge spectroscopy (XANES). During the X-ray spectroscopic measurements, the sample was maintained under electrochemical control in the pH 8.4 borate buffer electrolyte. The appearance of the distinctive Cr(VI) XANES pre-edge peak can be correlated with the transpassive wave in the cyclic voltammogram, and its disappearance with the corresponding reduction wave. The formation and reduction of Cr(VI) was reversible, and only small amounts were detected in the film. Cr(VI) in the passive film is not indefinitely stable, and it is completely absent after long periods of air exposure.

Bardwell, J.A.; Sproule, G.I.; MacDougall, B.; Graham, M.J. [National Research Council of Canada, Ottawa, ON (Canada). Inst. for Microstructural Sciences; Davenport, A.J.; Isaacs, H.S. [Brookhaven National Lab., Upton, NY (United States)

1991-12-31

407

In situ XANES detection of Cr(VI) in the passive film on Fe-26Cr  

SciTech Connect

The passive film on sputter deposited thin film Fe-26Cr electrodes has been examined using the technique of in situ X-ray absorption near edge spectroscopy (XANES). During the X-ray spectroscopic measurements, the sample was maintained under electrochemical control in the pH 8.4 borate buffer electrolyte. The appearance of the distinctive Cr(VI) XANES pre-edge peak can be correlated with the transpassive wave in the cyclic voltammogram, and its disappearance with the corresponding reduction wave. The formation and reduction of Cr(VI) was reversible, and only small amounts were detected in the film. Cr(VI) in the passive film is not indefinitely stable, and it is completely absent after long periods of air exposure.

Bardwell, J.A.; Sproule, G.I.; MacDougall, B.; Graham, M.J. (National Research Council of Canada, Ottawa, ON (Canada). Inst. for Microstructural Sciences); Davenport, A.J.; Isaacs, H.S. (Brookhaven National Lab., Upton, NY (United States))

1991-01-01

408

Investigation of the Noncondensable Effect and the Operational Modes of the Passive Condenser System  

SciTech Connect

An experimental study is performed to investigate the effect of noncondensable gas in a passive condenser system. A vertical condenser tube is submerged in a water pool where the heat transferred from the condenser tube is removed through boiling. Data are obtained for three operational modes of the passive condenser. Degradation of the condensation with noncondensable gas is investigated. The condensation heat transfer rate is enhanced by increasing the inlet steam flow rate and the system pressure. For the condenser submerged in a saturated water pool, strong primary pressure dependency is observed. A boundary layer-based condensation model and a simple condensation model with the interfacial friction factor correlation are developed. The model predictions are compared with the pure steam data, and the agreement is satisfactory.

Oh, Seungmin; Revankar, Shripad T. [Purdue University (United States)

2005-10-15

409

Prenatal passive transfer of Mycobacterium tuberculosis antibodies in Asian elephant (Elephas maximus) calves.  

PubMed

Asian elephant (Elephas maximus) dams and their newborn calves were tested for Mycobacterium tuberculosis antibodies in serum. Blood was drawn from dams prior to calving and from calves on their day of birth. All six calves born to tuberculosis-reactive dams were also tuberculosis reactive, suggesting prenatal passive placental transfer of tuberculosis antibodies. In contrast, all three calves born to tuberculosis-nonreactive dams lacked detectable tuberculosis antibodies in pre-suckling or day-of-birth blood samples. Of the living tuberculosis-reactive calves observed from 1 to 11 yr of age, none exhibited clinical signs of tuberculosis infection or became tuberculosis culture positive. This is the first report of prenatal passive placental transfer of tuberculosis antibodies in elephants and demonstrates that detectible tuberculosis antibodies in newborn elephant calves should not be assumed to correlate with clinical tuberculosis. PMID:25632691

McGee, Jennifer L; Wiedner, Ellen; Isaza, Ramiro

2014-12-01

410

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

PubMed

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 K(EVA-W) partition coefficients correlate well (r(2) = 0.87) with Log K(OW) values for selected pesticides and polychlorinated biphenyls (PCBs) where Log K(EVA-W) = 1.04 Log K(OW) + 0.22. EVA is a suitable polymer for passive sampling due to both its high affinity for organic compounds and its ease of coating at sub-micron film thicknesses on various substrates. Twelve-day field deployments were effective in detecting target compounds with good precision making EVA a potential multi-media fugacity meter. PMID:21093968

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

2011-02-01

411

The Relationship of Tropical Cyclone Convective Intensity to Passive Microwave Observations  

NASA Technical Reports Server (NTRS)

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.

Hood, Robbie E.; Guillory, Anthony; LaFontaine, Frank J.; Cecil, Dan; Heymsfield, Gerald; Arnold, James E. (Technical Monitor)

2002-01-01

412

A Passive Probe for Subsurface Oceans and Liquid Water in Jupiter's Icy Moons  

NASA Astrophysics Data System (ADS)

We present a method for passive detection of subsurface oceans and liquid water in Jovian icy moons using Jupiter's decametric radio emission (DAM). The DAM flux density exceeds 3,000 times the galactic background in the neighborhood of the Jovian icy moons, providing a signal that could be used for passive radio sounding. An instrument located between the icy moon and Jupiter could sample the DAM emission along with its echoes reflected in the ice layer of the target moon. Cross-correlating the direct emission with the echoes would provide a measurement of the subsurface ocean depth along with the dielectric properties of the ice shell. The technique is complementary to ice penetrating radar measurements in that it works best where interference due to Jupiter's strong decametric emission is the strongest.

Romero-Wolf, Andrew; Vance, Steve; Maiwald, Frank; Ries, Paul; Liewer, Kurt

2014-11-01

413

Passive NMIS Measurements to Estimate the Shape of Plutonium Assemblies  

SciTech Connect

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.

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

414

Correlation spectrometer  

DOEpatents

A correlation spectrometer can detect a large number of gaseous compounds, or chemical species, with a species-specific mask wheel. In this mode, the spectrometer is optimized for the direct measurement of individual target compounds. Additionally, the spectrometer can measure the transmission spectrum from a given sample of gas. In this mode, infrared light is passed through a gas sample and the infrared transmission signature of the gasses present is recorded and measured using Hadamard encoding techniques. The spectrometer can detect the transmission or emission spectra in any system where multiple species are present in a generally known volume.

Sinclair, Michael B. (Albuquerque, NM); Pfeifer, Kent B. (Los Lunas, NM); Flemming, Jeb H. (Albuquerque, NM); Jones, Gary D. (Tijeras, NM); Tigges, Chris P. (Albuquerque, NM)

2010-04-13

415

ChemCam Passive Reflectance Spectroscopy at Gale Crater, Mars  

NASA Astrophysics Data System (ADS)

The Laser-Induced Breakdown Spectrometer (LIBS) portion of the ChemCam instrument on the Mars Science Laboratory Curiosity rover uses 3 dispersive spectrometers to cover the ultraviolet (240-342 nm), visible (382-469 nm) and visible/near-infrared (474-906 nm) spectral regions at high spectral (<0.5nm) and spatial (0.65mrad) resolution. In active LIBS mode, light emitted from a laser-generated plasma is dispersed onto these spectrometers and used to detect elemental emission lines. Typical observations include 3 msec-exposure 'dark' spectra (acquired with the LIBS laser off) used to remove the background signal from the LIBS measurement. Similar 'passive' observations of the ChemCam calibration target holder can be made at similar times of day and at identical exposure times (to minimize variations from dark current). Because this target exhibits ~95% flat reflectance in the ~400-900 nm region, radiance spectra ratios (surface/calibration target) can be normalized to known calibration target lab spectra to produce relative reflectance spectra (400-900 nm) with an estimated accuracy of 10-20%. Initial results replicated the known spectral shape and overall reflectance values of the ChemCam calibration targets and green color chip on the Mastcam calibration target. Dust contamination was evident, although dust on the ChemCam calibration targets is minimized by their tilted placement on the rover deck. All ChemCam targets that were sunlit during LIBS acquisition (~80% of all measurements) provide 'dark' spectra for which relative reflectance spectra can be obtained. Owing to the dusty nature of the Gale landing sites, passive spectra observed to date exhibit spectral shapes indicative of ferric phases, similar to spectra of palagonitic soils. Most spectra are bracketed in reflectance by typical 'bright' and 'dark' spectra from the OMEGA and CRISM orbital spectrometers. Preliminary Mastcam reflectance spectra are similar, providing additional confidence regarding the first-order calibration of the ChemCam spectra. The spectral similarity to palagonitic soils is consistent with the results from the CheMin instrument for Rocknest sands. Changes in the 535 nm band depth are likely indicative of differences in the relative amount of ferric iron in crystalline phases. More strongly negative spectral slopes > 600 nm are typical of lower-reflectance, less dusty rock surfaces, whereas positive slopes < 600 nm are consistent with higher-reflectance, dustier surfaces. ChemCam elemental detections of Ca- and S-bearing veins correlate to high reflectance targets with some dust contamination. Spectra of the John_Klein and Cumberland drill tailings, as well as brushed and broken rock surfaces in the Yellowknife Bay area, exhibit much less 'red' spectral features, including inflections near 550 nm that are consistent with a number of ferrous and ferric iron-bearing clay mineral phases, similar to CheMin results. Ongoing work with ChemCam passive spectra will include efforts to utilize the UV spectral range (sensitive to iron content), investigate photometric effects of illumination variations on the calibration targets, and dust mitigation efforts. As Curiosity traverses toward Mt. Sharp, passive spectra will be used as an additional tool to remotely track variations in surface chemistry and mineralogy, particularly for iron-bearing sulfate, oxide, and clay minerals.

Johnson, J. R.; Bell, J. F.; Cloutis, E.; Bender, S.; Blaney, D. L.; Ehlmann, B. L.; Gasnault, O.; Kinch, K. M.; Le Mouelic, S.; Rice, M. S.; Wiens, R. C.; DeFlores, L.; Team, M.

2013-12-01

416

Gene-environment interactions in genetic epidemiology  

E-print Network

and the use of oral contraceptives. The methods developed here are especially appropriate for this data, as over half of all of the study participants have unknown genotype. 5 CHAPTER II JOINT LINKAGE DISEQUILIBRIUM AND LINKAGE MAPPING FOR COMPLEX PEDIGREES 2... the interaction between either a BRCA1 or BRCA2 mutation and both oral contraceptive usage and parity. Additionally, many other covariates, including age, family history of breast and ovarian cancer, personal history of breast cancer, history of gynecological...

Spinka, Christine Marie

2005-02-17

417

Face facts: Genes, environment, and clefts  

SciTech Connect

Cleft lip and/or palate provides an ideal, albeit complex, model for the study of human developmental anomalies. Clefting disorders show a mix of well-defined syndromic causes (many with single-gene or environmental etiologies) coupled with their more common presentation in the nonsyndromic form. This summary presents some insight into the genetic causes of, etiology of and animal models for cleft lip and/or palate. 79 refs.

Murray, J.C. [Univ. of Iowa, Iowa City IA (United States)

1995-08-01

418

A JavaScript Passive Evolution Calculator  

E-print Network

We present a JavaScript calculator which provides the redshift evolution of the luminosities and colors of passively evolving galaxies for a range of rest-frame filters. In its simplest form it gives the evolution of a single age stellar population formed at a given redshift. However, it can also incorporate morphological evolution in the galaxy population ("progenitor bias") and complex star formation histories of individual galaxies. The calculator is based on the models of van Dokkum & Franx (2001), with small updates.

Pieter G. van Dokkum; Marijn Franx

2005-01-12

419

A JavaScript Passive Evolution Calculator  

E-print Network

We present a JavaScript calculator which provides the redshift evolution of the luminosities and colors of passively evolving galaxies for a range of rest-frame filters. In its simplest form it gives the evolution of a single age stellar population formed at a given redshift. However, it can also incorporate morphological evolution in the galaxy population ("progenitor bias") and complex star formation histories of individual galaxies. The calculator is based on the models of van Dokkum & Franx (2001), with small updates.

Van Dokkum, P G; Dokkum, Pieter G. van; Franx, Marijn

2001-01-01

420

Passive Wireless SAW Sensors for IVHM  

NASA Technical Reports Server (NTRS)

NASA aeronautical programs require integrated vehicle health monitoring (IVHM) to ensure the safety of the crew and the vehicles. Future IVHM sensors need to be small, light weight, inexpensive, and wireless. Surface acoustic wave (SAW) technology meets all of these constraints. In addition it operates in harsh environments and over wide temperature ranges, and it is inherently radiation hardened. This paper presents a survey of research opportunities for universities and industry to develop new sensors that address anticipated IVHM needs for aerospace vehicles. Potential applications of passive wireless SAW sensors from ground testing to high altitude aircraft operations are presented, along with some of the challenges and issues of the technology.

Wilson, William C.; Perey, Daniel F.; Atkinson, Gary M.; Barclay, Rebecca O.

2008-01-01

421

Estimating animal population density using passive acoustics.  

PubMed

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

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

422

Passive Millimeter Wave Camera (PMMWC) at TRW  

NASA Technical Reports Server (NTRS)

Engineers at TRW, Redondo Beach, California, inspect the Passive Millimeter Wave Camera, a weather-piercing camera designed to see through fog, clouds, smoke and dust. Operating in the millimeter wave portion of the electromagnetic spectrum, the camera creates visual-like video images of objects, people, runways, obstacles and the horizon. A demonstration camera (shown in photo) has been completed and is scheduled for checkout tests and flight demonstration. Engineer (left) holds a compact, lightweight circuit board containing 40 complete radiometers, including antenna, monolithic millimeter wave integrated circuit (MMIC) receivers and signal processing and readout electronics that forms the basis for the camera's 1040-element focal plane array.

1997-01-01

423

Passive Millimeter Wave Camera (PMMWC) at TRW  

NASA Technical Reports Server (NTRS)

Engineers at TRW, Redondo Beach, California, inspect the Passive Millimeter Wave Camera, a weather-piercing camera designed to 'see' through fog, clouds, smoke and dust. Operating in the millimeter wave portion of the electromagnetic spectrum, the camera creates visual-like video images of objects, people, runways, obstacles and the horizon. A demonstration camera (shown in photo) has been completed and is scheduled for checkout tests and flight demonstration. Engineer (left) holds a compact, lightweight circuit board containing 40 complete radiometers, including antenna, monolithic millimeter wave integrated circuit (MMIC) receivers and signal processing and readout electronics that forms the basis for the camera's 1040-element focal plane array.

1997-01-01

424

Single laser beam based passive optical sorter  

NASA Astrophysics Data System (ADS)

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.

Brzobohatý, O.; Karasek, V.; Å iler, M.; Chvatal, L.; Cizmar, T.; Zemanek, P.

2013-03-01

425

Passivation-free solid state battery  

DOEpatents

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.

Abraham, Kuzhikalail M. (Needham, MA); Peramunage, Dharmasena (Norwood, MA)

1998-01-01

426

Passivation-free solid state battery  

DOEpatents

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.

Abraham, K.M.; Peramunage, D.

1998-06-16

427

Estimating animal population density using passive acoustics  

PubMed Central

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

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

428

Meteoroid flux from passive seismic experiment data  

NASA Technical Reports Server (NTRS)

The meteoroid flux hitting the moon is recomputed using new information on the decrease of seismic signal amplitude with range. The new data are principally 17 large meteoroid impacts whose locations have been computed from recordings at all four of the operating Passive Seismic Experiment stations. These data suggest a rapid decrease in amplitudes beyond about 2200 km (chord range) which was not suspected earlier. The new estimate predicts the abundance of meteoroids with masses between 500 and 50,000 g. The result is considerably lower than estimates from earth-based observations, and close to our previous estimate from long-period lunar seismic data.

Duennebier, F.; Dorman, J.; Lammlein, D.; Latham, G.; Nakamura, Y.

1975-01-01

429

Active and Passive Voice Recognizing the Active and the Passive Voice  

E-print Network

. Active: The teacher gave Julie a detention. Passive: Julie was given a detention by the teacher. Uses/or educational use in accordance with the Canada Copyright Act, and provided that proper acknowledgment is given University of Newfoundland, St. John's, NL, Canada, A1C 57S. MUN Writing Centre | www

deYoung, Brad

430

Production of Passives 1 The Production of Passives by Children with Specific Language Impairment  

E-print Network

Acquiring English or Cantonese Laurence B. Leonard Purdue University Anita M.-Y. Wong University of Hong language impairment (SLI) was studied in two languages, English and Cantonese. In both languages, the word, English and Cantonese passive sentences are quite different in other respects. We found that English

Stromswold, Karin

431

Development of object permanence as a correlate of dimensions of maternal care  

Microsoft Academic Search

A correlational study of 31 infants between the ages of 3 and 7 mo revealed that the development of positive decalage (i.e., scoring higher on person than on object permanence) is related to the maternal variables of communication and active achievement stimulation. Maternal variables not correlated with positive decalage were passive achievement stimulation, sensitivity, disruptiveness, and positive affective stimulation. Results

Saralea E. Chazan

1981-01-01

432

An investigation of a passively controlled haptic interface  

SciTech Connect

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.

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

433

FLEXIBLE WIRELESS PASSIVE PRESSURE SENSORS FOR BIOMEDICAL APPLICATONS  

E-print Network

models simulating abdominal aortic aneurysms (AAA) which incorporated a wired reference pressure of abdominal aortic aneurysms (AAA). Previous work demonstrated a passive wireless scheme used for pressure

434

Passive Superconducting Shielding: Experimental Results and Computer Models  

NASA Technical Reports Server (NTRS)

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.

Warner, B. A.; Kamiya, K.

2003-01-01

435

Demonstration of Passive Fuel Cell Thermal Management Technology  

NASA Technical Reports Server (NTRS)

The NASA Glenn Research Center is developing advanced passive thermal management technology to reduce the mass and improve the reliability of space fuel cell systems for the NASA Exploration program. The passive thermal management system relies on heat conduction within highly thermally conductive cooling plates to move the heat from the central portion of the cell stack out to the edges of the fuel cell stack. Using the passive approach eliminates the need for a coolant pump and other cooling loop components within the fuel cell system which reduces mass and improves overall system reliability. Previous development demonstrated the performance of suitable highly thermally conductive cooling plates and integrated heat exchanger technology to collect the heat from the cooling plates (Ref. 1). The next step in the development of this passive thermal approach was the demonstration of the control of the heat removal process and the demonstration of the passive thermal control technology in actual fuel cell stacks. Tests were run with a simulated fuel cell stack passive thermal management system outfitted with passive cooling plates, an integrated heat exchanger and two types of cooling flow control valves. The tests were run to demonstrate the controllability of the passive thermal control approach. Finally, successful demonstrations of passive thermal control technology were conducted with fuel cell stacks from two fuel cell stack vendors.

Burke, Kenneth A.; Jakupca, Ian; Colozza, Anthony; Wynne, Robert; Miller, Michael; Meyer, Al; Smith, William

2012-01-01

436

Passive recirculation in the National Launch System's fuel feedlines  

NASA Technical Reports Server (NTRS)

This report contains the passive recirculation tests on the fuel feedline of the National Launch System (NLS). The majority of testing was performed in February 1992, at the National Institute of Standards and Technology in Boulder, CO. The primary objective was to characterize passive recirculation in the NLS fuel feedline. The objective was met by observing the passive recirculation in a one-fifth scale model of the feedline with clear glass sections. The testing was recorded on video tape and with photographs. A description of the testing apparatus and support equipment is included. The experiment indicates that passive recirculation was occurring; higher angles from the horizontal transfer more heat.

Wilson, W. R.; Holt, K. A.

1993-01-01

437

[Passive and active middle ear implants].  

PubMed

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:19353457

Beutner, D; Hüttenbrink, K B

2009-05-01

438

Improvement of passive THz camera images  

NASA Astrophysics Data System (ADS)

Terahertz technology is one of emerging technologies that has a potential to change our life. There are a lot of attractive applications in fields like security, astronomy, biology and medicine. Until recent years, terahertz (THz) waves were an undiscovered, or most importantly, an unexploited area of electromagnetic spectrum. The reasons of this fact were difficulties in generation and detection of THz waves. Recent advances in hardware technology have started to open up the field to new applications such as THz imaging. The THz waves can penetrate through various materials. However, automated processing of THz images can be challenging. The THz frequency band is specially suited for clothes penetration because this radiation does not point any harmful ionizing effects thus it is safe for human beings. Strong technology development in this band have sparked with few interesting devices. Even if the development of THz cameras is an emerging topic, commercially available passive cameras still offer images of poor quality mainly because of its low resolution and low detectors sensitivity. Therefore, THz image processing is very challenging and urgent topic. Digital THz image processing is a really promising and cost-effective way for demanding security and defense applications. In the article we demonstrate the results of image quality enhancement and image fusion of images captured by a commercially available passive THz camera by means of various combined methods. Our research is focused on dangerous objects detection - guns, knives and bombs hidden under some popular types of clothing.

Kowalski, Marcin; Piszczek, Marek; Palka, Norbert; Szustakowski, Mieczyslaw

2012-10-01

439

Silicone wristbands as personal passive samplers.  

PubMed

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

O'Connell, Steven G; Kincl, Laurel D; Anderson, Kim A

2014-03-18

440

Silicone Wristbands as Personal Passive Samplers  

PubMed Central

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 Kow 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

2014-01-01

441

Passive and active middle ear implants  

PubMed Central

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

Beutner, Dirk; Hüttenbrink, Karl-Bernd

2011-01-01

442

Nondiffuse elastic and anelastic passive imaging.  

PubMed

The property at the basis of passive acoustic imaging is that, taken any two points, one of them can be seen as the source of the waves and the other as the recording station. This property, which was shown to hold also in nondiffuse fields, is here exploited: (1) to allow an undistorted passive imaging through the simple use of the statistical mode to estimate wave velocity, (2) to determine the azimuth of the instantaneous Huygens sources of the noise wavefield, and (3) to measure, provided that the noise bandwidth is wide with respect to that of the local system, the material dissipation constant as a function of frequency. The authors applied this theory to study the seismic noise field in the Ravenna, North-Central Italy, shore area and found it capable to provide velocity dispersion curves matching those of independent surveys, to track the sources of seismic noise to a few major firms in Ravenna port, with the prevailing source switching at the time scale of seconds, and to measure the dissipation quality factor Q at approximately 20 independent of frequency in the range 1-30 Hz. PMID:20329839

Mulargia, Francesco; Castellaro, Silvia

2010-03-01

443

Passive Damping of Spacraft-Structures  

NASA Astrophysics Data System (ADS)

For a wide range of spacecraft structures dynamic loads are critical. The structural stresses caused by these loads can be reduced by the increase of mechanical damping. A simple, lightweight and reliable method is artificial friction damping which is applied in many areas of classical mechanical engineering. Friction damping covers potential to save mass and cost and can increase the service life of structures. It is capable of suppressing a wide range of mechanical vibrations. The method is low priced, simple in manufacturing and application as well as maintenance-free. The paper describes the work on the design, development and experimental testing of passive damping methods applied for S/C lightweight structures. The expected dynamic loads relevant for future Reusable Launch Vehicles (RLVs) are investigated from present point of view. A possibility is shown where friction elements are integrated between the layers of sandwich panels. In a further example friction elements are implemented into a fin-model representative for a RLV-demonstrator. Here, theoretical investigations show a mass saving potential of almost 30%. Further possibilities for application in future RLV technologies, mass saving as well as life-span extension potential of such passive damping devices are subjects of investigation.

Romberg, O.

2002-01-01

444

Passive broad-spectrum influenza immunoprophylaxis.  

PubMed

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

Berry, Cassandra M; Penhale, William J; Sangster, Mark Y

2014-01-01

445

Integrated bias removal in passive radar systems  

NASA Astrophysics Data System (ADS)

A passive coherent location (PCL) system exploits the ambient FM radio or television signals from powerful local transmitters, which makes it ideal for covert tracking. In a passive radar system, also known as PCL system, a variety of measurements can be used to estimate target states such as direction of arrival (DOA), time difference of arrival (TDOA) or Doppler shift. Noise and the precision of DOA estimation are main issues in a PCL system and methods such as conventional beam forming (CBF) algorithm, algebraic constant modulus algorithm (ACMA) are widely analyzed in literature to address them. In practical systems, although it is necessary to reduce the directional ambiguities, the placement of receivers closed to each other results in larger bias in the estimation of DOA of signals, especially when the targets move off bore-sight. This phenomenon leads to degradation in the performance of the tracking algorithm. In this paper, we present a method for removing the bias in DOA to alleviate the aforementioned problem. The simulation results are presented to show the effectiveness of the proposed algorithm with an example of tracking airborne targets.

Subramaniam, M.; Punithakumar, K.; McDonald, M.; Kirubarajan, T.

2008-04-01

446

Exploring passive transfer in muskoxen (Ovibos moschatus).  

PubMed

Poor calf production and ill thrift in 3-4 mo olds are common limiting problems in raising and maintaining captive muskoxen (Ovibos moschatus). Acute onset of a rapidly progressing enteritis and septicemia in neonatal calves (2-7 days of age) caused by Escherichia coli not normally considered pathogenic in domestic animals is a serious problem in many captive muskoxen facilities. Serum immunoglobulin G (IgG) levels, total protein, albumin, and globulin levels in captive periparturient muskox females and their neonatal calves were compared with levels found in other species in which these parameters have been well described. Results showed that all females in the study had IgG present in their serum (mean = 1,232.14 mg/dl, SD = 178.34 mg/dl, as measured via radial immunodiffusion). Calves were probably born agammaglobulinemic or hypogammaglobulinemic. IgG levels quickly rose in calves after initial colostrum intake to levels similar to those seen in other domestic ruminants. Our results suggest that passive transfer of immunity in muskoxen is similar to what is reported in domestic livestock and that reference ranges from domestic cattle may be used to assist interpretation of serum IgG levels in muskoxen. In addition, the positive relationship between serum protein and globulin levels with serum IgG levels is similar to that reported for Holstein cattle and thus provides a useful indicator of passive transfer in muskoxen. PMID:17469276

Rosa, Cheryl; Miller, Debra; Gray, Matthew J; Merrill, Anita; Vann, Tammie; Blake, John

2007-03-01

447

A Comparison between Lightning Activity and Passive Microwave Measurements  

NASA Technical Reports Server (NTRS)

A recent examination of data from the Lightning Imaging Sensor (LIS) and the TRMM Microwave Imager (TMI) suggests that storm with the highest frequency of lightning also possess the most pronounced microwave scattering signatures at 37 and 85 GHz. This study demonstrates a clear dependence between lightning and the passive microwave measurements, and accentuates how direct the relationship really is between cloud ice and lightning activity. In addition, the relationship between the quantity of ice content and the frequency of lightning (not just the presence of lightning) , is consistent throughout the seasons in a variety of regimes. Scatter plots will be presented which show the storm-averaged brightness temperatures as a function of the lightning density of the storms (L/Area) . In the 85 GHz and 37 GHz scatter plots, the