| 1. |
- Bott, Lukas Thomas, et al.
(författare)
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Coulomb dissociation of O-16 into He-4 and C-12
- 2023
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Ingår i: NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022. - : EDP Sciences. - 2100-014X. ; 279
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Konferensbidrag (refereegranskat)abstract
- We measured the Coulomb dissociation of O-16 into He-4 and C-12 within the FAIR Phase-0 program at GSI Helmholtzzentrum fur Schwerionenforschung Darmstadt, Germany. From this we will extract the photon dissociation cross section O-16(alpha,gamma)C-12, which is the time reversed reaction to C-12(alpha,gamma)O-16. With this indirect method, we aim to improve on the accuracy of the experimental data at lower energies than measured so far. The expected low cross section for the Coulomb dissociation reaction and close magnetic rigidity of beam and fragments demand a high precision measurement. Hence, new detector systems were built and radical changes to the (RB)-B-3 setup were necessary to cope with the high-intensity O-16 beam. All tracking detectors were designed to let the unreacted O-16 ions pass, while detecting the C-12 and He-4.
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| 2. |
- Butler, Peter, et al.
(författare)
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Coulomb excitation of pear-shaped nuclei
- 2019
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Ingår i: - : EDP Sciences. ; , s. 01007-01007
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Konferensbidrag (refereegranskat)abstract
- There is a large body of evidence that atomic nuclei can undergo octupole distortion and assume the shape of a pear. This phenomenon is important for measurements of electric-dipole moments of atoms, which would indicate CP violation and hence probe physics beyond the Standard Model of particle physics. Isotopes of both radon and radium have been identified as candidates for such measurements. Here, we have observed the low-lying quantum states in 224Rn and 226Rn by accelerating beams of these radioactive nuclei. We show that radon isotopes undergo octupole vibrations but do not possess static pear-shapes in their ground states. We conclude that radon atoms provide less favourable conditions for the enhancement of a measurable atomic electric-dipole moment.
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| 3. |
- Caminis, Argyro, et al.
(författare)
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Psychosocial predictors of sexual initiation and high-risk sexual behaviors in early adolescence.
- 2007
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Ingår i: Child and Adolescent Psychiatry and Mental Health. - : Springer Science and Business Media LLC. - 1753-2000. ; 1:1, s. 14-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: This longitudinal study examined psychosocial factors associated with risky sexual behavior in early adolescence.METHODS: Data were collected through a self-report survey, the Social and Health Assessment (SAHA), which was administered in three waves between 2001 and 2003 to a cohort of incoming sixth grade students in the public school system (149 classes at 17 middle and high schools, N = 1,175) of a small northeastern city in the United States.We first examined whether internalizing and externalizing problems in sixth grade, and the rate of change in these factors during middle school, were predictive of sexual initiation two years later, when most of the sample was in eighth grade. We then assessed whether internalizing and externalizing problems in sixth grade, and the rate of change in these factors during middle school, were predictive of engaging in high risk sexual behavior over the subsequent two years.RESULTS: Externalizing factors are more predictive of sexual risk in early adolescence than are internalizing factors. Specifically, substance use and violent delinquency over the course of middle school were associated with higher, while anxiety with lower, sexual initiation rates during middle school. Additionally, increased substance use over the course of middle school was associated with greater likelihood of engaging in high risk sexual behavior.CONCLUSION: By identifying particular psychosocial risk factors among young adolescents, the findings of this study have implications for designing multi-dimensional programs aimed at preventing health-compromising sexual behavior among young teens.
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| 4. |
- Elmelid, Andrea, et al.
(författare)
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Depressive symptoms, anxiety and academic motivation in youth : Do schools and families make a difference?
- 2015
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Ingår i: Journal of Adolescence. - : Wiley. - 0140-1971 .- 1095-9254. ; 45, s. 174-182
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Tidskriftsartikel (refereegranskat)abstract
- This longitudinal study aimed to examine the association between depressive and anxiety symptoms and academic motivation by gender, and whether positive school and family factors would be associated with academic motivation, in spite of the presence of such symptoms. Study participants were predominantly economically disadvantaged youths aged 13-15 years in a Northeastern US urban public school system. The Social and Health Assessment (SAHA) served as the basis for a survey undertaken in 2003 and 2004 with information being used from students who participated at both time points (N = 643). Multiple linear regression analyses showed that depressive symptoms were negatively associated with academic motivation, while anxiety was positively related to academic motivation in both genders. Teacher support, school attachment and parental control were positively related to academic motivation even in the presence of internalizing problems. The negative association of depressive symptoms with academic motivation may be potentially decreased by attachment to school.
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| 5. |
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| 6. |
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| 7. |
- Martin, Andrés, et al.
(författare)
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Early to bed : a study of adaptation among sexually active urban adolescent girls younger than age sixteen.
- 2005
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - : Elsevier BV. - 0890-8567 .- 1527-5418. ; 44:4, s. 358-67
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To examine the association between sexual activity among urban adolescent girls and four global measures of psychosocial adaptation (academic motivation, school achievement, depressive symptoms, and expectations about the future).METHOD: Data derived from the Social and Health Assessment, a self-report survey administered in 1998 to students in the public school system in New Haven, CT (149 classes at 17 middle and high schools).RESULTS: Of 1,413 respondents (57% black, 28% Hispanic; mean age 13.4 +/- 1.7 years), 414 (29%) acknowledged prior sexual intercourse; the proportions of sexually active girls in 6th, 8th, and 10th grades were 14%, 30%, and 50%, respectively. In multivariate analyses of covariance, sexual activity was significantly associated with all four measures of psychosocial adaptation (p < .001). Other correlates of at least one measure of maladaptation included socioeconomic status, sensation seeking, and lower school grade (p < .001 for each), peer pressure (p < .01), and black ethnicity, and the interaction of sexual activity by lower school grade (p < .05 for each).CONCLUSIONS: Compared with their sexually naive peers, sexually active adolescent girls had lower scores on global measures of psychosocial adaptation. These findings have clinical, policy, and research relevance to a vulnerable population at high risk of teenage pregnancy and sexually transmitted diseases.
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| 8. |
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| 9. |
- Nylander, Tommy, et al.
(författare)
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Relationship between Structure and Fluctuations of Lipid Nonlamellar Phases Deposited at the Solid-Liquid Interface
- 2017
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 121:13, s. 2705-2711
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Tidskriftsartikel (refereegranskat)abstract
- The structure and dynamics of nanostructure films formed by mixtures of soy phosphatidylcholine and glycerol dioleate at the silicon aqueous interface were studied by grazing incidence neutron spin echo spectroscopy (GINSES), specular and off-specular neutron, reflectometry, and small-angle X-ray diffraction. Reverse hexagonal (Hr) and micellar cubic phase (Fd3m) layers at: the solid liquid interface have been identified with neutron reflectometry measurements. A preferred orientation of the liquid crystalline (LC) domains was observed only for the anisotropic,H-II phase. The size of the LC domains was found to be about 1 micrometer as estimated from the width of the diffraction peaks. GINSES revealed that the cubic phase forms rather rigid films. In comparison, the HE film was more flexible, appearing as a modified undulation spectrum of the cylinders due to the interaction with the substrate.
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| 10. |
- Ruchkin, Vladislav, et al.
(författare)
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Violence exposure and psychopathology in urban youth : the mediating role of posttraumatic stress.
- 2007
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Ingår i: Journal of Abnormal Child Psychology. - : Springer Science and Business Media LLC. - 0091-0627 .- 1573-2835. ; 35:4, s. 578-93
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the mechanisms underlying the development of violence exposure sequelae is essential to providing effective treatments for traumatized youth. This longitudinal study examined the mediating role of posttraumatic stress in the relationship between violence exposure and psychopathology, and compared the mediated models by gender. Urban adolescents (n=1,358) were surveyed using the Social and Health Assessment. The proposed relationships were examined using Structural Equation Modeling. Posttraumatic stress fully mediated the relationships between victimization and depression and anxiety in girls, and partially so in boys. In addition, posttraumatic stress partially mediated the relationships between violence exposure and commission of violence in boys. Current findings support the longitudinal effects of violence exposure on adolescent mental health. Posttraumatic stress represents a unique mechanism for the development of psychopathology in girls and is also related to negative outcomes in boys. These findings have direct implications for prevention and rehabilitation efforts among violence exposed youth.
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