| 1. |
- Ablikim, M., et al.
(författare)
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Measurements of (XcJ)-> K+K-K+K- decays
- 2006
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 642:3, s. 197-202
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Tidskriftsartikel (refereegranskat)abstract
- Using 14M psi(2S) events taken with the BESII detector, chi(cJ) -> 2(K+K-) decays are studied. For the four-kaon final state, the branching fractions are B(chi(c0,1,2) ->.2(K+K-)) = (3.48 +/- 0.23 +/- 0.47) x 10(-3), (0.70 +/- 0.13 +/- 0.10) x 10(-3), and (2.17 +/- 0.20 +/- 0.31) x 10(-3). For the phi K+K- final state, the branching fractions, which are measured for the first time, are B(chi(c0,1,2) -> phi K+K-) = (1.03 +/- 0.22 +/- 0.15) x 10(-3), (0.46 +/- 0.16 +/- 0.06) x 10(-3), and (1.67 +/- 0.26 +/- 0.24) x 10(-4). For the phi phi final state, B(chi(c0,2) -> phi phi) = (0.94 +/- 0.21 +/- 0.13) x 10(-3) and (1.70 +/- 0.30 +/- 0.25) x 10(-3).
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| 2. |
- Baker, Laura, et al.
(författare)
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Resting heart rate and the development of antisocial behavior from age 9 to 14 : genetic and environmental influences
- 2009
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Ingår i: Development and psychopathology (Print). - 0954-5794 .- 1469-2198. ; 21:3, s. 939-960
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Tidskriftsartikel (refereegranskat)abstract
- The genetic and environmental basis of a well-replicated association between antisocial behavior (ASB) and resting heart rate was investigated in a longitudinal twin study, based on two measurements between the ages of 9 and 14 years. ASB was defined as a broad continuum of externalizing behavior problems, assessed at each occasion through a composite measure based on parent ratings of trait aggression, delinquent behaviors, and psychopathic traits in their children. Parent ratings of ASB significantly decreased across age from childhood to early adolescence, although latent growth models indicated significant variation and twin similarity in the growth patterns, which were explained almost entirely by genetic influences. Resting heart rate at age 9-10 years old was inversely related to levels of ASB but not change patterns of ASB across age or occasions. Biometrical analyses indicated significant genetic influences on heart rate during childhood, as well as ASB throughout development from age 9 to 14. Both level and slope variation were significantly influenced by genetic factors. Of importance, the low resting heart rate and ASB association was significantly and entirely explained by their genetic covariation, although the heritable component of heart rate explained only a small portion (1-4%) of the substantial genetic variance in ASB. Although the effect size is small, children with low resting heart rate appear to be genetically predisposed toward externalizing behavior problems as early as age 9 years old.
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| 3. |
- Tuvblad, Catherine, 1968-, et al.
(författare)
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A common genetic factor explains the covariation among ADHD ODD and CD symptoms in 9-10 year old boys and girls
- 2009
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Ingår i: Journal of Abnormal Child Psychology. - : Springer Science and Business Media LLC. - 0091-0627 .- 1573-2835. ; 37:2, s. 153-167
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies examining the covariation among Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD) and Conduct Disorder (CD) have yielded inconsistent results. Some studies have concluded that the covariation among these symptoms is due to common genetic influences, whereas others have found a common environmental overlap. The present study investigated the genetic and environmental correlations among these three childhood disorders, based on a sample of 1,219 twins, age 9-10 years. A latent externalizing behavior factor was found to explain the covariance among ADHD, ODD and CD symptoms. Genetic influences explained more than half of the variance in this externalizing factor in both boys and girls. There were also unique genetic and environmental influences in each set of symptoms, suggesting some etiological independence of the three disorders. Our findings have implications for molecular genetic studies trying to identify susceptibility genes for these disorders.
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| 4. |
- Tuvblad, Catherine, 1968-, et al.
(författare)
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Genetic and environmental stability differs in reactive and proactive aggression
- 2009
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Ingår i: Aggressive Behavior. - : Wiley. - 0096-140X .- 1098-2337. ; 35:6, s. 437-452
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine stability and change in genetic and environmental influences on reactive (impulsive and affective) and proactive (planned and instrumental) aggression from childhood to early adolescence. The sample was drawn from an ongoing longitudinal twin study of risk factors for antisocial behavior at the University of Southern California (USC). The twins were measured on two occasions: ages 9-10 years (N=1,241) and 11-14 years (N=874). Reactive and proactive aggressive behaviors were rated by parents. The stability in reactive aggression was due to genetic and nonshared environmental influences, whereas the continuity in proactive aggression was primarily genetically mediated. Change in both reactive and proactive aggression between the two occasions was mainly explained by nonshared environmental influences, although some evidence for new genetic variance at the second occasion was found for both forms of aggression. These results suggest that proactive and reactive aggression differ in their genetic and environmental stability, and provide further evidence for some distinction between reactive and proactive forms of aggression.
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| 5. |
- Tuvblad, Catherine, 1968-, et al.
(författare)
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The development of psychopathic traits from childhood to adolescence
- 2009
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Ingår i: Behavior Genetics. - : Springer Science and Business Media LLC. - 0001-8244 .- 1573-3297. ; 39:6, s. 685-685
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Previous research has shown that genetic factors are important in the stability of psychopathic personality from ages 17–24 years (D. M. Blonigen, B. M. Hicks, R. F. Krueger, C. J. Patrick, W. G. Iacono, 2006, Journal of Abnormal Psychology, 85–95) and ages 16–19 years (M. Forsman, P. Lichtenstein, H. Andershed, H. Larsson, 2008, Journal of Abnormal Psychology, 606–17). However, these studies did not examine the developmental trajectory of psychopathy, and they only evaluated psychopathy at two time points. The present study examined to what extent genetic and environmental effects influence initial level and change in psychopathic personality measured on three time. The USC Twin Study of Risk Factors for Antisocial Behavior is a longitudinal study of >600 twin pairs born 1990–1996 (L. A. Baker, M. Barton, D. I. Lozano, A. Raine, J. H. Fowler, 2006, Twin Research, 933–40). Psychopathic personality in the twins were assessed with the Child Psychopathy Scale (D. R. Lynam, 1997, Journal of Abnormal Psychology, 425–38) which was administered in interview format to the twins and their caregivers when the twins were aged 9–10 years, 11–14 years and 15–18 years old: N= 1,441 twins. Phenotypic Latent Growth Curve models were fit in MPlus (L. K. Muthén & B. O. Muthén, 1998–2007, Los Angeles, CA). Age variation within each wave of assessment is a powerful design for examining genetic and environmental influences on level and change (J. J. McArdle, 2006, Twin Research, 343–59) and was fit using Proc Mixed (SAS Institute, 2005). For both parent and self-report ratings of psychopathic traits, the best-fitting phenotypic growth model was a linear model, indicating significant growth in psychopathic traits, decreasing over time on average in parent reported ratings and increasing over time in youth selfreported ratings. For parent reports, slope variation was significant, suggesting that individuals have different trajectories. For youth-self-reports the slope variation was non-significant, suggesting that every-one is changing in a similar way. Next, the genetic and environmental etiology of individual differences in both level and change in psychopathic traits was investigated. A full model was fit which included growth variation, and where non-shared environment, shared environment, and additive genetic variation contributed to both intercept and slope. For both parent and self-reported ratings of psychopathic traits, an AE model was the most parsimonious model. For parent reports: the intercept variance due to additive genetic effects was 90% and the non-shared environment was 10%, the slope variance due to genetic effects was 51% and the non-shared environment was 49%. For youth self-reports, intercept variance due to genetic effects was 67% and the non-shared environment was 33%, the slope variance due to additive genetic effects was 27% and the non-shared environment was 73%. These longitudinal data demonstrate that genetic influences are important in both level and change in psychopathic personality, based on bothparental and self-reports. A significant growth across age was found. Interestingly, the slope was negative when examining parental ratings of psychopathic personality traits indicating a reduction in these traits whereas, the slope was positive when examining youth self-reports, indicating an increase in these traits.
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| 6. |
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| 7. |
- Wyner, Joshua D., et al.
(författare)
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The genetics of motor disinhibition : a longitudinal analysis of the Go/NoGo task in twins
- 2009
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Ingår i: Behavior Genetics. - : Springer Science and Business Media LLC. - 0001-8244 .- 1573-3297. ; 39:6, s. 692-692
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- To understand the etiology of antisocial behavior it is essential to investigate the origins of inhibition and impulsivity. While impulsive personality traits (such as those examined by the Barrett Impulsivity Scale) appear to increase over time, motor impulsivity (as measured by stop-signal tasks) appears to decrease. To investigate the origins of this change in motor impulsivity in more detail, we examined the genetic and environmental influences on performance in a visual Go/NoGo task for twins from the USC Twin Project. Errors of commission (NoGo errors) were used to measure motor impulsivity and were assessed longitudinally on up to three occasions at ages 9–10, ages 12–13, and ages 14–15 years old. In addition to classical biometric genetic models to investigate developmental changes in genetic (A), shared (C) and non-shared (E) environmental influences across age, we also employed latent growth curve modeling to investigate genetic and environmental influences on individual differences in change in impulsivity across age. Univariate model fitting results suggest a primarily A and E origin for NoGo task performance within each of the three occasions with estimates for the genetic contribution ranging from A=0.20–0.30. Over time, subjects task performance tended to improve (i.e., fewer errors of commission), phenotypically. Growth curve models suggest that this improvement over time is primarily due to unique environmental effects, which increased in importance with age. Genetic effects, in contrast, played a key roll in determining initial error levels. Taken together, these results suggest that the genetic influences on impulsive behavior take effect early in life, prior to the onset of adolescence, and that environmental influences play an increasingly important role during development. The significance of these findings is discussed, along with implications for further research
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| 8. |
- Zheng, Mo, et al.
(författare)
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A Monte Carlo evaluation of different model fit indices for analysis of multi-rater twin data
- 2009
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Ingår i: Behavior Genetics. - : Springer Science and Business Media LLC. - 0001-8244 .- 1573-3297. ; 39:6, s. 695-695
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This study examined the performance of different model fit indices in multivariate multi-rater twin research. A Monte Carlo simulation design was used to generate six competing multi-trait multi-rater genetic models. Three commonly used model fit indices, including Akaike’s Information Criterion (AIC), Bayesian Information Criterion (BIC), and Root Mean Square Error of Approximation (RMSEA), were compared in terms of power and type I error in selecting the best fitting model under different true factor model conditions. Results showed that no model fit index is perfect in measuring model fit. BIC generally performs best when differentiating simple one-, two-, and three-factor models. However, AIC has the lowest error rate in distinguishing hierarchical factor models against simple confirmatory factor models. Thus both AIC and BIC have to be considered in practical research. The utility of the Monte Carlo simulation was demonstrated through the analysis of Reactive Proactive Aggression Questionnaire (RPQ)(Raine, 1997) and Child Behavior Checklist (CBCL) data in a sample collected from the USC Twin Study of Risk Factors for Antisocial Behavior (Baker et al., 2006). All analyses were conducted in the Mplus software. (Baker, L. A., Barton, M., Lozano, D. I., Raine, A. & Fowler, J. H., 2006, The Southern California Twin Register at the University of Southern California: II. Twin Research and Human Genetics, 9, 933–40; Raine A, Dodge K, Loeber R, Gatzke-Kopp L, Lynam D, Reynolds C, et al., 2006, The Reactive–Proactive Aggression Questionnaire: Differential correlates of reactive and proactive aggression in adolescent boys. Aggressive Behavior, 32, 159–171.)
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| 9. |
- Zheng, Mo, et al.
(författare)
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Multivariate genetic and environmental modeling among childhood externalizing disorders across different modality
- 2008
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Ingår i: Behavior Genetics. - : Springer Science and Business Media LLC. - 0001-8244 .- 1573-3297. ; 38:6, s. 653-653
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Previous research has shown the importance of genetic factors in understanding the etiology of co-morbidity among childhood externalizing disorders, but results have not been consistent across studies in terms of relative weight assigned to genetic, shared and non-shared environmental factors. Specifically, heritability estimates may vary across different measurements, different time points and different informants. This study aimed to use multivariate genetic and environmental modeling to find best fitting models for co-morbid externalizing disorders, including attention deficit-hyperactivity disorder (ADHD), oppositional defiant disorder (ODD) and conduct disorder (CD), and to investigate how results change among multiple outcomes across different modality. The sample included 605 twin pairs recruited from the Southern California Twin Registry. Three independent analyses were run to examine (1) how genetic and environmental influences differ across measurement instruments using Diagnostic Interview Schedule for Children (DISC-IV) and Child Behavior Checklist (CBCL), (2) how genetic and environmental influences change developmentally from age 9 to age 12, and (3) how genetic and environmental influences vary across different informants using both caregiver’s and teacher’s CBCL responses. Four alternative multivariate models were tested in each analysis, including a one factor common pathway model, a two factor common pathway model, a hierarchical model, and a Cholesky decomposition model. Results showed that the Cholesky model fit best for the multimeasurement data and longitudinal data, while hierarchical model fit best for the multi-informant data. Co-morbidity common to caregiver and teacher informant reports, and co-morbidity unique to each informant were both influenced largely by genetic influences. Shared environmental contributions, however, were not significant in explaining either the shared co-morbidity or co-morbidity unique to each informant
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