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Interaction Effects (interaction + effects)
Kinds of Interaction Effects Selected AbstractsInteraction Effects in the Theory of Planned Behavior: The Interplay of Self-Identity and Past BehaviorJOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 11 2007Joanne R. Smith This research used a revised theory of planned behavior (TPB) model, which incorporated self-identity and past behavior,and the interaction between these constructs,in order to improve the model's predictive power in relation to consumer behavior (purchasing one's preferred beer). At Time 1, respondents (N = 108) completed measures of attitudes, perceived behavioral control, subjective norm, self-identity, past behavior, and intentions. Behavior was assessed 1 week later. All predictors were positively related to intentions. Self-identity and past behavior interacted to influence intentions: Self-identity had a stronger influence on intentions at low, rather than high, levels of past behavior. Intentions and past behavior were predictive of Time 2 behavior. These findings emphasize the need to consider identity issues in the TPB. [source] Interaction Effects of Citrus Rootstocks, Salinity and Tylenchulus semipenetrans Parasitism on Osmotically Active IonsJOURNAL OF PHYTOPATHOLOGY, Issue 2 2002P. W. MASHELA High densities of Tylenchulus semipenetrans and slow decline symptoms are dominant in citrus-producing areas with high salinity. Currently, no commercial citrus rootstock is both nematode-resistant and salt-tolerant. Interaction effects of citrus rootstocks, salinity and T. semipenetrans were evaluated for the partitioning of salinity ions (Cl and Na) and K in microplots. Treatments comprised six citrus rootstocks with wide ranges of salt tolerance, 0 and 3 mols NaCl + 0.25 mols CaCl2 l,1 water and 0 and 856 300 nematodes. At harvest, eight months after salinity treatments, the three,factor interaction was significant (P=0.05) for the alteration in the partitioning of salinity ions and K. Nematodes generally increased salinity ions in leaves and reduced salinity ions in roots and K in both leaves and roots. Thus, management of nematodes is critical in areas with salinity problems. [source] Spousal Concordance for Alcohol Dependence: Evidence for Assortative Mating or Spousal Interaction Effects?ALCOHOLISM, Issue 5 2007Julia D. Grant Background: Alcohol dependence (AD) is among the most common psychiatric disorders, and impacts the health and well-being of problem drinkers, their family members, and society as a whole. Although previous research has consistently indicated that genetic factors contribute to variance in risk for AD, little attention has been paid to nonrandom mating for AD. When assortative mating occurs for a heritable trait, spouses are genetically correlated and offspring are at increased risk of receiving high-risk genes from both parents. The primary goal of the present analyses is to test hypotheses about the source(s) and magnitude of spousal associations for AD using a twin-spouse design. Methods: DSM-IV AD (without the clustering criterion) was assessed via telephone interview for 5,974 twin members of an older cohort of the Australian Twin Register (born 1902,1964) and 3,814 spouses of the twins. Quantitative genetic modeling was used to determine the extent to which variability in risk for AD was influenced by genetic factors, the extent of spousal association for AD, and whether the association was attributable to assortative mating, reciprocal spousal interaction, or both processes. Results: Genetic factors explained 49% of the variance in risk for AD. There was no evidence of gender differences in the spousal interaction effect, the degree of rater bias, or the association between the twin's report of spouse AD and the spouse's AD phenotype. Either the assortative mating parameter or the spousal interaction parameter could be removed from the model without a significant decrement in fit, but both could not be dropped simultaneously, suggesting a lack of power to differentiate between these 2 causes of spousal correlation. When both effects were included in the model, the spousal correlation was 0.29, the assortative mating coefficient was 0.45 (i.e., "like marries like"), and the reciprocal spousal interaction coefficient was ,0.10 (i.e., after controlling for assortative mating, the additional impact of spousal interactions is slightly protective). Conclusions: These analyses provide evidence of significant spousal associations for AD, with assortative mating increasing spouse similarity and spousal interaction effects decreasing it after controlling for assortative mating. Although the genetic impact is modest, assortative mating results in an increased proportion of offspring exposed to 2 alcoholic parents and the associated detrimental environmental sequelae, and increases the likelihood of offspring inheriting high-risk genes from both parents. [source] Association between tobacco control policies and smoking behaviour among adolescents in 29 European countriesADDICTION, Issue 11 2009Anne Hublet ABSTRACT Aims To investigate the associations between well-known, cost-effective tobacco control policies at country level and smoking prevalence among 15-year-old adolescents. Design Multi-level modelling based on the 2005,06 Health Behaviour in School-aged Children Study, a cross-national study at individual level, and with country-level variables from the Tobacco Control Scale and published country-level databases. Setting Twenty-nine European countries. Participants A total of 25 599 boys and 26 509 girls. Main outcome measures Self-reported regular smoking defined as at least weekly smoking, including daily smoking (dichotomous). Findings Interaction effects between gender and smoking policies were identified, therefore boys and girls were analysed separately. Large cross-national differences in smoking prevalence were documented. Intraclass correlations (ICC) of 0.038 (boys) and 0.035 (girls) were found. In the final multi-level model for boys, besides the significance of the individual variables such as family affluence, country-level affluence and the legality of vending machines were related significantly to regular smoking [b(country affluence) = ,0.010; b(partial restriction vending machines) = ,0.366, P < 0.05]. Price policy was of borderline significance [b(price policy) = ,0.026, P = 0.050]. All relationships were in the expected direction. The model fit is not as good for girls; only the legality of vending machines had a borderline significance in the final model [b(total ban vending machines) = ,0.372, P = 0.06]. Conclusions For boys, some of the currently recommended tobacco control policies may help to reduce smoking prevalence. However, the model is less suitable for girls, indicating gender differences in the potential efficacy of smoking policies. Future research should address this issue. [source] Personality traits and health-risk behaviours in university studentsEUROPEAN JOURNAL OF PERSONALITY, Issue 8 2009Ryan Y. Hong Abstract Relations between personality and health-risk behaviours in university undergraduates were examined using multiple measures of personality across multiple samples (N,=,1151). Big Five personality variables, at both factor and facet levels, were used to predict three specific health-risk behaviours: (a) tobacco consumption, (b) alcohol consumption and (c) speeding in an automobile. Our findings showed that low Conscientiousness and low Agreeableness were uniformly associated with this cluster of potentially health damaging behaviours. Extraversion was additionally associated with alcohol use. Interaction effects were found between Conscientiousness and Agreeableness on smoking and (for men only) on drinking. Other personality variables not centrally related to the Big Five, such as Risk-Taking (high) and Integrity (low), were also implicated in the present health-risk behaviours. Copyright © 2009 John Wiley & Sons, Ltd. [source] Untersuchungen zum Einfluß einer Xylanaseergänzung in Legehennenrationen auf Weizenbasis 2.JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1-2 2000Mitteilung: Auswirkungen auf die Leistungsparameter Summary The influence of a xylanase supplement on performance of laying hens fed different energy-graded, wheat-based rations was tested in a 12-week trial. Two varieties of wheat with different extraction viscosity were selected. In addition to the control ration, three test rations with reduced energy contents of ,3, ,6, and ,9% were used. Sixteen groups, each consisting of 30 hens were kept in single cages. At the beginning of the experiment hens were 24 weeks old. Single eggmass and daily eggmass production showed a statistically significant difference. This was not caused by the enzyme supplement or the energy content, but by the variety of wheat. Interaction effects between variety of wheat, enzyme supplement and energy content became obvious with regard to the yolk colour. The influence of the enzyme on the yolk colour is positive and statistically highly significant. Thus, the addition of xylanase to wheat-based rations does not affect the performance parameters of laying hens positively. Zusammenfassung In einem zwölfwöchigem Leistungsversuch wurde der Einfluß einer Xylanaseergänzung in Legehennenrationen auf Weizenbasis mit abgestuftem Energiegehalt auf die Leistungsparameter untersucht. Dazu wurden zwei Weizensorten (Alidos + Caprimus) mit unterschiedlicher Extraktviskosität ausgesucht und neben den jeweiligen Kontrollrationen drei Versuchsrationen mit abgestuftem Energiegehalt (,3%, ,6%, ,9%) eingesetzt. Den 16 Versuchsgruppen waren jeweils 30 Legehennen zugeordnet, die bei Versuchsbeginn 24 Lebenswochen alt waren. Es handelte sich um eine Einzelkäfigaufstallung. Statistisch signifikante Unterschiede ergaben sich bei der Einzeleimasse und der täglichen Eimasseproduktion, die sich jedoch weder dem Enzymzusatz noch dem Energiegehalt zuordnen ließen, sondern durch die Weizensorte bedingt waren. Es zeigten sich Wechselwirkungen zwischen Weizensorte, Enzymsupplementierung und Energiegehalt auf die Dotterfarbe. Es war ein statistisch hochsignifikanter positiver Enzymeinfluß auf die Dotterfarbe zu erkennen. Insgesamt gesehen, zeigte sich auch in diesem Legehennenversuch keine positive Wirkung der Xylanaseergänzung auf die Leistungsparamter zu Rationen auf Weizenbasis. [source] Interaction Effects of Citrus Rootstocks, Salinity and Tylenchulus semipenetrans Parasitism on Osmotically Active IonsJOURNAL OF PHYTOPATHOLOGY, Issue 2 2002P. W. MASHELA High densities of Tylenchulus semipenetrans and slow decline symptoms are dominant in citrus-producing areas with high salinity. Currently, no commercial citrus rootstock is both nematode-resistant and salt-tolerant. Interaction effects of citrus rootstocks, salinity and T. semipenetrans were evaluated for the partitioning of salinity ions (Cl and Na) and K in microplots. Treatments comprised six citrus rootstocks with wide ranges of salt tolerance, 0 and 3 mols NaCl + 0.25 mols CaCl2 l,1 water and 0 and 856 300 nematodes. At harvest, eight months after salinity treatments, the three,factor interaction was significant (P=0.05) for the alteration in the partitioning of salinity ions and K. Nematodes generally increased salinity ions in leaves and reduced salinity ions in roots and K in both leaves and roots. Thus, management of nematodes is critical in areas with salinity problems. [source] The Relationships of the Level of Response to Alcohol and Additional Characteristics to Alcohol Use Disorders Across Adulthood: A Discrete-Time Survival AnalysisALCOHOLISM, Issue 9 2009Ryan S. Trim Background:, A low level of response (LR) to alcohol has been shown to relate to a higher risk for alcohol use disorders (AUDs). However, no previous research has examined the association between LR and the development of AUDs in the context of additional robust risk factors for AUDs. This study evaluated whether LR and other related characteristics predicted the occurrence of AUDs across adulthood using discrete-time survival analysis (DTSA). Methods:, A total of 297 probands from the San Diego Prospective Study reported on the LR to alcohol, a family history (FH) of AUDs, the typical drinking quantity, the age of drinking onset, the body mass index and the age at the baseline (T1) assessment. Alcohol use disorders (AUDs) were evaluated at the 10-year (T10), T15, T20, and T25 follow-ups. Results:, A low LR to alcohol predicted AUD occurrence over the course of adulthood even after controlling for the effects of other robust risk factors. Interaction effects revealed that the impact of FH on AUDs was only observed for subjects with high T1 drinking levels, and probands with high T1 drinking were at high risk for AUDs regardless of their age of onset. Conclusions:, The findings illustrate that LR is a unique risk factor for AUDs across adulthood, and not simply a reflection of a broader range of risk factors. The continued investigation of how LR is related to AUD onset later in life will help inform treatment providers about this high-risk population, and future longitudinal evaluations will utilize DTSA to assess rates of AUD remission as well as the onset of drinking outcomes in adolescent samples. [source] Interaction effects in high-mobility two-dimensional electron and hole systemsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2005A. K. Savchenko Abstract Electron,electron interaction in the presence of impurities is studied in two-dimensional systems where the parameter kBT,/, changes from 0.1 to 10 (, is the momentum relaxation time). This corresponds to the intermediate and ballistic regimes of electron interaction. We analyse the interaction correction to the Drude conductivity in terms of recent theories and show that it is strongly dependent on the character of the impurity potential. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Cognitive-existential group psychotherapy for women with primary breast cancer: A randomised controlled trialPSYCHO-ONCOLOGY, Issue 6 2003David W. Kissane Background. We conducted a randomised, controlled trial of cognitive-existential group therapy (CEGT) for women with early stage breast cancer receiving adjuvant chemotherapy with the aim of improving mood and mental attitude to cancer. Methods. Women were randomised to 20 sessions of weekly group therapy plus 3 relaxation classes or to a control arm receiving 3 relaxation classes. Assessments, independently done at baseline, 6 and 12 months, included a structured psychiatric interview and validated questionnaires covering mood, attitudes to cancer, family relationships, and satisfaction with therapy. Results. Three hundred and three of 491 (62%) eligible patients participated over 3 years. Distress was high pre-intervention: 10% were diagnosed as suffering from major depression, 27% from minor depression and 9% from anxiety disorders. On an intention-to-treat analysis, there was a trend for those receiving group therapy (n=154) to have reduced anxiety (p=0.05, 2-sided) compared to controls (n=149). Women in group therapy also showed a trend towards improved family functioning compared to controls (p=0.07, 2-sided). The women in the groups reported greater satisfaction with their therapy (p<0.001, 2-sided), appreciating the support and citing better coping, self-growth and increased knowledge about cancer and its treatment. They valued the CEGT therapy. Overall effect size for the group intervention was small (d=0.25), with cancer recurrence having a deleterious effect in three of the 19 therapy groups. Psychologists as a discipline achieved a moderate mean effect size (d=0.52). Conclusion. CEGT is a useful adjuvant psychological therapy for women with early stage breast cancer. Interaction effects between group members and therapists are relevant to outcome. Group-as-a-whole effects are powerful, but the training and experience of the therapist is especially critical to an efficacious outcome. Copyright © 2003 John Wiley & Sons, Ltd. [source] Value-chain innovation in aquaculture: insights from a New Zealand case studyR & D MANAGEMENT, Issue 4 2006Jayaram K. Sankaran We report a case study of value-chain innovation in a niche, export-oriented aquaculture industry, namely, Chinook/King salmon, that contrasts with the much more common Atlantic/Norwegian salmon. The firm in question is vertically integrated, thus offering a ,cradle-to-grave' vista of innovation that spans ,production' (i.e. farming), processing, marketing, and distribution. A major finding is the need for a delicate balance between the relative expenditures on production research and developmental research in integrated aquaculture firms, especially those that focus on niche species. Interaction effects between the two research strands complicate the trade-off: production research adds value at the fish farm by lowering the unit cost of production , and in turn facilitates new product development as it is easier to add value to a lower-cost product than a higher-cost product. From the case study findings, we synthesize a process model of value-chain innovation that is applicable for integrated aquaculture firms. We also induce several implications for the management of Research & Development and innovation in such firms. [source] S03.3: Interaction effects and population attributable risks for smoking and alcohol on laryngeal cancer and its subsites: a case-control studyBIOMETRICAL JOURNAL, Issue S1 2004Heribert Ramroth No abstract is available for this article. [source] Some benefits of dichotomization in psychiatric and criminological researchCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 2 2000Professor David P. Farrington PhD FBA Background The product-moment correlation r is widely used in criminology and psychiatry to measure strength of association. However, most criminological and psychiatric variables contravene its underlying assumptions. Aim To compare statistical measures of association based on dichotomous variables with the use of r. Method Explanatory variables for delinquency are investigated in the Pittsburgh Youth Study using a sample of 506 boys aged 13,14. Results Dichotomization does not necessarily cause a decrease in measured strength of associations. Conclusions about the most important explanatory variables for delinquency were not greatly affected by using dichotomous as opposed to continuous variables, by different dichotomization splits, or by using logistic versus OLS multiple regression. Non-linear relationships, interaction effects and multiple risk factor individuals were easily studied using dichotomous data. Conclusions Dichotomization produces meaningful findings that are easily understandable to a wide audience. Measures of association for dichotomous variables, such as the odds ratio, have many advantages and are often more realistic and meaningful measures of strength of relationship than the product-moment correlation r. Copyright © 2000 Whurr Publishers Ltd. [source] GUARDIANSHIP IN CONTEXT: IMPLICATIONS FOR BURGLARY VICTIMIZATION RISK AND PREVENTION,CRIMINOLOGY, Issue 4 2007PAMELA WILCOX Survey data from 4,227 Seattle residents nested within 100 "neighborhoods" (census tracts) were analyzed to discern interrelationships between various dimensions of individual-level and neighborhood-level guardianship. We focused on four dimensions of guardianship,physical (target hardening), personal (home occupancy), social (informal control), and natural (surveillance through environmental design),at both individual and neighborhood levels. A multilevel opportunity, theoretical framework guided hypotheses, which suggests that each of the four dimensions of individual guardianship would be related more negatively to burglary as each of the four dimensions of aggregate guardianship increased. Multilevel logistic regression analysis revealed support for many of such hypothesized moderating effects of aggregate guardianship. More specifically, 6 of the 16 possible interaction effects were statistically significant at the .05 level and an additional 3 interaction effects were significant at the .10 level. In particular, individuallevel target hardening, place management, and natural surveillancewere related more negatively to burglary as neighborhood-level target hardening increased, as neighborhood-level informal social control increased, and as neighborhood-level natural surveillance increased. [source] THE INTERACTION OF ANTISOCIAL PROPENSITY AND LIFE-COURSE VARYING PREDICTORS OF DELINQUENT BEHAVIOR: DIFFERENCES BY METHOD OF ESTIMATION AND IMPLICATIONS FOR THEORY,CRIMINOLOGY, Issue 2 2007GRAHAM C. OUSEY Recent criminological research has explored the extent to which stable propensity and life-course perspectives may be integrated to provide a more comprehensive explanation of variation in individual criminal offending. One line of these integrative efforts focuses on the ways that stable individual characteristics may interact with, or modify, the effects of life-course varying social factors. Given their consistency with the long-standing view that person,environment interactions contribute to variation in human social behavior, these theoretical integration attempts have great intuitive appeal. However, a review of past criminological research suggests that conceptual and empirical complexities have, so far, somewhat dampened the development of a coherent theoretical understanding of the nature of interaction effects between stable individual antisocial propensity and time-varying social variables. In this study, we outline and empirically assess several of the sometimes conflicting hypotheses regarding the ways that antisocial propensity moderates the influence of time-varying social factors on delinquent offending. Unlike some prior studies, however, we explicitly measure the interactive effects of stable antisocial propensity and time-varying measures of selected social variables on changes in delinquent offending. In addition, drawing on recent research that suggests that the relative ubiquity of interaction effects in past studies may be partly from the poorly suited application of linear statistical models to delinquency data, we alternatively test our interaction hypotheses using least-squares and tobit estimation frameworks. Our findings suggest that method of estimation matters, with interaction effects appearing readily in the former but not in the latter. The implications of these findings for future conceptual and empirical work on stable propensity/time-varying social variable interaction effects are discussed. [source] REASSESSING NONLINEARITY IN THE URBAN DISADVANTAGE/VIOLENT CRIME RELATIONSHIP: AN EXAMPLE OF METHODOLOGICAL BIAS FROM LOG TRANSFORMATION,CRIMINOLOGY, Issue 4 2003LANCE HANNON Sociologists and criminologists have become increasingly concerned with nonlinear relationships and interaction effects. For example, some recent studies suggest that the positive relationship between neighborhood disadvantage and violent crime is nonlinear with an accelerating slope, whereas other research indicates a nonlinear decelerating slope. The present paper considers the possibility that this inconsistency in findings is partially caused by lack of attention to an important methodological concern. Specifically, we argue that researchers have not been sensitive to the ways in which logarithmic transformation of the dependent variable can bias tests for nonlinearity and statistical interaction. We illustrate this point using demographic and violent crime data for urban neighborhoods, and we propose an alternative procedure to log transformation that involves the use of weighted least-squares regression, heteroscedasticity consistent standard errors, and diagnostics for influential observations. [source] A study of primary nucleation of calcium oxalate monohydrate: II.CRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2004Effect of urinary species Abstract Kidney stones consist of various organic and inorganic compounds. Calcium oxalate monohydrate (COM) is the main inorganic constituent of kidney stones. However, the mechanisms for the formation of calcium oxalate kidney stones are not well understood. In this regard, there are several hypotheses including nucleation, crystal growth and/or aggregation of formed COM crystals. The effect of some urinary species such as oxalate, calcium, citrate, and protein on nucleation and crystallization characteristics of COM is determined by measuring the weight of formed crystals and their size distributions under different chemical conditions, which simulate the urinary environment. Statistical experimental designs are used to determine the interaction effects among various factors. The data clearly show that oxalate and calcium promote nucleation and crystallization of COM. This is attributed to formation of a thermodynamically stable calcium oxalate monohydrate resulting from supersaturation. Citrate, however, inhibits nucleation and further crystal growth. These results are explained on the basis of the high affinity of citrate to combine with calcium to form soluble calcium citrate complexes. Thus, citrate competes with oxalate ion for binding to calcium cations. These conditions decrease the amount of free calcium ions available to form calcium oxalate crystals. In case of protein (mucin), however, the results suggest that no significant effect could be measured of mucin on nucleation and crystal growth. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Response simulation and seismic assessment of highway overcrossingsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 9 2010Anastasios Kotsoglou Abstract Interaction of bridge structures with the adjacent embankment fills and pile foundations is generally responsible for response modification of the system to strong ground excitations, to a degree that depends on soil compliance, support conditions, and soil mass mobilized in dynamic response. This paper presents a general modeling and assessment procedure specifically targeted for simulation of the dynamic response of short bridges such as highway overcrossings, where the embankment soil,structure interaction is the most prevalent. From previous studies it has been shown that in this type of interaction, seismic displacement demands are magnified in the critical bridge components such as the central piers. This issue is of particular relevance not only in new design but also in the assessment of the existing infrastructure. Among a wide range of issues relevant to soil,structure interaction, typical highway overcrossings that have flexible abutments supported on earth embankments were investigated extensively in the paper. Simulation procedures are proposed for consideration of bridge-embankment interaction effects in practical analysis of these structures for estimation of their seismic performance. Results are extrapolated after extensive parametric studies and are used to extract ready-to-use, general, and parameterized capacity curves for a wide range of possible material properties and geometric characteristics of the bridge-embankment assembly. Using two instrumented highway overpasses as benchmark examples, the capacity curves estimated using the proposed practical procedures are correlated successfully with the results of explicit incremental dynamic analysis, verifying the applicability of the simple tools developed herein, in seismic assessment of existing short bridges. Copyright © 2009 John Wiley & Sons, Ltd. [source] The effect of foundation embedment on inelastic response of structuresEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4 2009Mojtaba Mahsuli Abstract In this research, a parametric study is carried out on the effect of soil,structure interaction on the ductility and strength demand of buildings with embedded foundation. Both kinematic interaction (KI) and inertial interaction effects are considered. The sub-structure method is used in which the structure is modeled by a simplified single degree of freedom system with idealized bilinear behavior. Besides, the soil sub-structure is considered as a homogeneous half-space and is modeled by a discrete model based on the concept of cone models. The foundation is modeled as a rigid cylinder embedded in the soil with different embedment ratios. The soil,structure system is then analyzed subjected to a suit of 24 selected accelerograms recorded on alluvium deposits. An extensive parametric study is performed for a wide range of the introduced non-dimensional key parameters, which control the problem. It is concluded that foundation embedment may increase the structural demands for slender buildings especially for the case of relatively soft soils. However, the increase in ductility demands may not be significant for shallow foundations with embedment depth to radius of foundation ratios up to one. Comparing the results with and without inclusion of KI reveals that the rocking input motion due to KI plays the main role in this phenomenon. Copyright © 2008 John Wiley & Sons, Ltd. [source] Seismic response of intake towers including dam,tower interactionEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2009M. A. Millán Abstract The seismic response of the intake,outlet towers has been widely analyzed in recent years. The usual models consider the hydrodynamic effects produced by the surrounding water and the interior water, characterizing the dynamic response of the tower,water,foundation,soil system. As a result of these works, simplified added mass models have been developed. However, in all previous models, the surrounding water is assumed to be of uniform depth and to have infinite extension. Consequently, the considered added mass is associated with only the pressures created by the displacements of the tower itself. For a real system, the intake tower is usually located in proximity to the dam and the dam pressures may influence the equivalent added mass. The objective of this paper is to investigate how the response of the tower is affected by the presence of the dam. A coupled three-dimensional boundary element-finite element model in the frequency domain is employed to analyze the tower,dam,reservoir interaction problem. In all cases, the system response is assumed to be linear, and the effect of the internal fluid and the soil,structure interaction effects are not considered. The results suggest that unexpected resonance amplifications can occur due to changes in the added mass for the tower as a result of the tower,dam,reservoir interaction. Copyright © 2008 John Wiley & Sons, Ltd. [source] Forced vibration testing of buildings using the linear shaker seismic simulation (LSSS) testing methodEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 7 2005Eunjong Yu Abstract This paper describes the development and numerical verification of a test method to realistically simulate the seismic structural response of full-scale buildings. The result is a new field testing procedure referred to as the linear shaker seismic simulation (LSSS) testing method. This test method uses a linear shaker system in which a mass mounted on the structure is commanded a specified acceleration time history, which in turn induces inertial forces in the structure. The inertia force of the moving mass is transferred as dynamic force excitation to the structure. The key issues associated with the LSSS method are (1) determining for a given ground motion displacement, xg, a linear shaker motion which induces a structural response that matches as closely as possible the response of the building if it had been excited at its base by xg (i.e. the motion transformation problem) and (2) correcting the linear shaker motion from Step (1) to compensate for control,structure interaction effects associated with the fact that linear shaker systems cannot impart perfectly to the structure the specified forcing functions (i.e. the CSI problem). The motion transformation problem is solved using filters that modify xg both in the frequency domain using building transfer functions and in the time domain using a least squares approximation. The CSI problem, which is most important near the modal frequencies of the structural system, is solved for the example of a linear shaker system that is part of the NEES@UCLA equipment site. Copyright © 2005 John Wiley & Sons, Ltd. [source] Non-linear behavior of mass concrete in three-dimensional problems using a smeared crack approachEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2005H. Mirzabozorg Abstract A smeared crack approach has been proposed to model the static and dynamic behavior of mass concrete in three-dimensional space. The proposed model simulates the tensile fracture on the mass concrete and contains pre-softening behavior, softening initiation, fracture energy conservation and strain rate effects under dynamic loads. The validity of the proposed model has been checked using the available experimental results under static and dynamic loads. The direct and indirect displacement control algorithms have been employed under incremental increasing static loads. It was found that the proposed model gives excellent results and crack profiles when compared with the available data under static loads. The Koyna Dam in India has been used to verify the dynamic behavior of the proposed model. It was found that the resulting crack profiles were in good agreement with the available experimental results. Finally, the Morrow Point Dam was analyzed, including the dam,reservoir interaction effects, to consider its non-linear seismic behavior. It was found that the resulting crack profiles were in good agreement with the contour of maximum principal stresses and no numerical instability occurred during the analysis. Copyright © 2004 John Wiley & Sons, Ltd. [source] Gene,environment interactions and alcohol use and dependence: current status and future challengesADDICTION, Issue 6 2009Carmen S. Van Der Zwaluw ABSTRACT Aim To discuss the current status of gene,environment interaction research with regard to alcohol use and dependence. Further, we highlight the difficulties concerning gene,environment studies. Methods Overview of the current evidence for gene,environment interactions in alcohol outcomes, and of the associated challenges in gene,environment studies. Results Attention to the causative roles of gene,environment interactions in alcohol use and dependence is increasing. Studies with twin designs are beginning to examine gene-shared environment effects, and animal studies have investigated gene,environment interaction effects on alcohol intake in primates. Thirteen studies incorporated gene,environment interactions in examining alcohol use or dependence in humans. These studies held a variety of candidate genes and environmental risk factors and their heterogeneity made it impossible to draw firm general conclusions. Conclusions Challenges for future gene,environment studies are abundant, and consist of, for example, the development of clear theoretical assumptions about neurobiological mechanisms and the recruitment of large longitudinal samples that already start in childhood. Replication is essential to prevent an overload of false-positive results. Despite the difficulties, it is crucial to include gene,environment interactions in future studies in order to unravel the aetiological factors of human alcohol outcomes. [source] Observed and predicted reproduction of Ceriodaphnia dubia exposed to chloride, sulfate, and bicarbonate,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2010Peter J. Lasier Abstract Chronic toxicities of Cl,, SO, and HCO to Ceriodaphnia dubia were evaluated in low- and moderate-hardness waters using a three-brood reproduction test method. Toxicity tests of anion mixtures were used to determine interaction effects and to produce models predicting C. dubia reproduction. Effluents diluted with low- and moderate-hardness waters were tested with animals acclimated to low- and moderate-hardness conditions to evaluate the models and to assess the effects of hardness and acclimation. Sulfate was significantly less toxic than Cl, and HCO in both types of water. Chloride and HCO toxicities were similar in low-hardness water, but HCO was the most toxic in moderate-hardness water. Low acute-to-chronic ratios indicate that toxicities of these anions will decrease quickly with dilution. Hardness significantly reduced Cl, and SO toxicity but had little effect on HCO. Chloride toxicity decreased with an increase in Na+ concentration, and HCO toxicity may have been reduced by the dissolved organic carbon in effluent. Multivariate models using measured anion concentrations in effluents with low to moderate hardness levels provided fairly accurate predictions of reproduction. Determinations of toxicity for several effluents differed significantly depending on the hardness of the dilution water and the hardness of the water used to culture test animals. These results can be used to predict the contribution of elevated anion concentrations to the chronic toxicity of effluents; to identify effluents that are toxic due to contaminants other than Cl,, SO, and HCO; and to provide a basis for chemical substitutions in manufacturing processes. Environ. Toxicol. Chem. 2010;29:347,358. Published 2009 SETAC [source] Psychosocial outcomes in children two years after epilepsy surgery: Has anything changed?EPILEPSIA, Issue 4 2008Irene M. Elliott Summary Purpose: We prospectively explored psychosocial outcomes in children (7,18 years) 2 years after epilepsy surgery. This study built on our previous one that examined these children 1 year after surgery. Methods: Twenty children were studied using the Child Behavior Checklist (CBCL; a parent report instrument of potential behavioral and social problems) preoperatively, 1 year and 2 years after surgery. A comparison group of 12 children with medically refractory seizures was examined at comparable times. We conducted mixed factorial ANOVAs to determine group, time, and interaction effects, and regression analyses to assess factors driving significant (p , 0.05) interactions. We also investigated the proportion of children scoring in the abnormal range over time. Results: Significant main effects of time were observed on total behavior, externalizing, aggression, and delinquent behavior scales, with both groups reporting improvement. Main effects of group were observed for withdrawn and total competence scales, with the surgical group demonstrating favorable scores. Significant group × time interactions were observed on the social and social problems subscales. On both subscales, the surgical group demonstrated improvement over time, whereas the nonsurgical group experienced decline. Fifty percent of the surgical group remained seizure-free. Seizure status and number of antiepileptic medications predicted changes in social scores. We did not observe a significant regression model for the social problems subscale. Discussion: These findings suggest that change in social function may take time to develop after surgery. Prospective studies designed for longer periods are required to determine if improvements in other psychosocial domains are seen over time. [source] Toward a New Sexual Selection Paradigm: Polyandry, Conflict and Incompatibility (Invited Article)ETHOLOGY, Issue 12 2003Jeanne A. Zeh Darwin's recognition that male,male competition and female choice could favor the evolution of exaggerated male traits detrimental to survival set the stage for more than a century of theoretical and empirical work on sexual selection. While this Darwinian paradigm represents one of the most profound insights in biology, its preoccupation with sexual selection as a directional evolutionary force acting on males has diverted attention away from the selective processes acting on females. Our understanding of female reproduction has been further confounded by discreet female mating tactics that have perpetuated the illusion of the monogamous female and masked the potential for conflict between the sexes. With advances in molecular techniques leading to the discovery that polyandry is a pervasive mating strategy, recognition of these shortcomings has brought the study of sexual selection to its current state of flux. In this paper, we suggest that progress in two key areas is critical to formulation of a more inclusive, sexual selection paradigm that adequately incorporates selection from the female perspective. First, we need to develop a better understanding of male × female and maternal × paternal genome interactions and the role that polyandry plays in providing females with non-additive genetic benefits such as incompatibility avoidance. Consideration of these interaction effects influencing natural selection on females is important because they can complicate and even undermine directional sexual selection on males. Secondly, because antagonistic coevolution maintains a balance between opposing sides that obscures the conflict itself, many more experimental evolution studies and interventionist investigations (e.g. gene knockouts) are needed to tease apart male manipulative adaptations and female counter-adaptations. It seems evident that the divisiveness and controversy that has plagued sexual selection theory since Darwin first proposed the idea has often stalled progress in this important field of evolutionary biology. What is now needed is a more pluralistic and integrative approach that considers natural as well as sexual selection acting on females, incorporates multiple sexual selection mechanisms, and exploits advances in physiology and molecular biology to understand the mechanisms through which males and females achieve reproductive success. [source] GENETIC STUDY: Interaction of SLC6A4 and DRD2 polymorphisms is associated with a history of delirium tremensADDICTION BIOLOGY, Issue 1 2010Victor M. Karpyak ABSTRACT Several genetic polymorphisms have been reported to be associated with alcohol withdrawal seizures (AWS) and delirium tremens (DT). To replicate and further explore these findings, we investigated the effects of 12 previously reported candidate genetic variations in two groups of alcohol-dependent European Americans with a history of withdrawal, which differed according to the presence (n = 112) or absence (n = 92) of AWS and/or DT. Associations of AWS and/or DT with the genomic and clinical characteristics and gene,gene interaction effects were investigated using logistic regression models. None of the polymorphisms were significantly associated with AWS/DT after correction for multiple testing. However, we found a significant interaction effect of the SLC6A4 promoter polymorphism (5-HTTLPR) and DRD2 exon 8 single nucleotide polymorphism rs6276 on AWS and/or DT history (P = 0.009), which became more significant after adjustment for lifetime maximum number of drinks consumed per 24 hours (P < 0.001). Subsequent analysis revealed an even stronger association of the SLC6A4,DRD2 interaction with DT (P < 0.0001), which remained significant after Bonferroni correction. Results reveal decreased likelihood of DT in alcoholics that carry the DRD2 rs6276 G allele and SLC6A4 LL genotype. This study provides the first evidence to implicate the interaction between serotonin and dopamine neurotransmission in the etiology of DT. Replication is necessary to verify this potentially important finding. [source] Examining dispositional and situational effects on outgroup attitudes,EUROPEAN JOURNAL OF PERSONALITY, Issue 4 2009Joke Meeus Two research lines have dominated the quest for the antecedents of outgroup attitudes. Whereas the first has viewed outgroup attitudes as a result of individual differences, the second stressed the importance of the intergroup situation. In order to investigate the interplay of individual differences and situational characteristics, key predictors of the individual differences perspective (i.e. right-wing authoritarianism or RWA, and social dominance orientation or SDO) and the intergroup relations perspective (i.e. ingroup identification and ingroup threat) were simultaneously tested. Two studies revealed additive but no interaction effects of RWA and SDO, ingroup identification and threat. Additionally, Study 1 showed that threat effects remain limited to the outgroup that is portrayed as threatening and do not generalize to other outgroups. Copyright © 2009 John Wiley & Sons, Ltd. [source] Ideology,Driven opinion formation in Europe: The case of attitudes towards the third sector in SwedenEUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 4 2001STAFFAN KUMLIN This paper uses attitudes towards the third sector in Sweden to test general assumptions about how citizens in West European political systems apply ideological schemas as shortcuts to political preferences. Attitudes towards the third sector are found to be affected by all ideological schemas reflected in the Swedish party system (state,market, Christian traditionalism, and growth,ecology). Contrary to what is implied by findings from America, these effects are very stable across socio,economic groups (especially those of the dominant statemarket schema). Similarly, no interaction effects of political sophistication could be traced, and the relative impact of the schemas remains the same regardless of whether or not the third sector is presented as an alternative to the welfare state. The implications of these findings for the nature of public opinion formation in ideologically clear and structured political systems are discussed. [source] Acute Hypervolaemia Improves Arterial Oxygen Pressure in Athletes with Exercise-Induced HypoxaemiaEXPERIMENTAL PHYSIOLOGY, Issue 4 2003Gerald S. Zavorsky The aim of this study was to determine the effect of acute plasma volume expansion on arterial blood-gas status during 6.5 min strenuous cycling exercise comparing six athletes with and six athletes without exercise-induced arterial hypoxaemia (EIAH). We hypothesized that plasma volume expansion could improve arterial oxygen pressure in a homogeneous sample of athletes - those with EIAH. In this paper we have extended the analysis and results of our recently published surprising findings that lengthening cardiopulmonary transit time did not improve arterial blood-gas status in a heterogeneous sample of endurance cyclists. One 500 ml bag of 10% Pentastarch (infusion condition) or 60 ml 0.9% saline (placebo) was infused prior to exercise in a randomized, double-blind fashion on two different days. Power output, cardiac output, oxygen consumption and arterial blood gases were measured during strenuous exercise. Cardiac output and oxygen consumption were not affected by acute hypervolaemia. There were group × condition interaction effects for arterial oxygen pressure and alveolar-arterial oxygen pressure difference, suggesting that those with hypoxaemia experienced improved arterial oxygen pressure (+4 mmHg) and lower alveolar-arterial oxygen pressure difference (-2 mmHg) with infusion. In conclusion, acute hypervolaemia improves blood-gas status in athletes with EIAH. The impairment of gas exchange occurs within the first minute of exercise, and is not impaired further throughout the remaining duration of exercise. This suggests that arterial oxygen pressure is only minimally mediated by cardiac output. 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