| 1. |
- Varju, Katalin, et al.
(författare)
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Experimental studies of attosecond pulse trains
- 2005
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Ingår i: Laser Physics. - 1054-660X. ; 15:6, s. 888-898
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental measurements of attosecond pulse trains. The characterization of the pulses uses a spectral interferometry technique that is implemented with a Mach-Zehnder interferometer. This allows us to manipulate independently the pump and probe pulses for a wide range of applications. By letting the attosecond pulses pass through metallic films, we can in particular compensate for the intrinsic chirp of the attosecond pulses corresponding to the plateau spectral region, thus getting pulses as short as 170 attoseconds-only 1.2 optical cycles at the central frequency. The measurement technique is also applicable for determination of the group delay of thin XUV-transparent films and relative delay in the photoionization process. Our experimental method is applied to attosecond pulse trains created by 35- and 9-fs laser pulses, and the shortest train observed consists of three or four pulses.
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| 2. |
- Gustafsson, Per E, 1981-, et al.
(författare)
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Cortisol levels and psychosocial factors in preadolescent children
- 2006
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Ingår i: Stress and Health. - : Wiley. - 1532-3005 .- 1532-2998. ; 22:1, s. 3-9
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Tidskriftsartikel (refereegranskat)abstract
- Regarding the relationship between psychosocial factors and health, one model of explanation states that psychosocial stress constitutes a principal mediator connecting psychosocial factors to health outcome, affecting the body through psychobiological mechanisms. This relationship has scarcely been studied in children. In the present study the relation between diurnal cortisol secretion and psychosocial factors [socio-economic status (SES), immigrant status and impact of psychiatric symptoms] was investigated in a normal population of 6-12 year old children (n = 273). Salivary cortisol levels were measured in the early morning, late morning and in the evening during three consecutive days. Parents answered demographic questionnaires and teachers answered psychiatric questionnaires concerning the children. Children exposed to one or more of the factors of psychosocial load (n = 117) had significantly higher morning (p < 0.001) and evening (p = 0.029) cortisol levels as well as total daily cortisol secretion [measured by the area under the curve (AUC), p = 0.003] compared to the group of children with none of the factors (n = 156). Different psychosocial stressors seemed to influence different parts of the diurnal cortisol curve. In conclusion, this study indicates that even children exposed to a moderate degree of psychosocial load differ in their cortisol levels compared to non-exposed children.
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| 3. |
- Gustafsson, Per E., 1981-, et al.
(författare)
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Diurnal cortisol levels and cortisol response in youths with obsessive-compulsive disorder
- 2008
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Ingår i: Neuropsychobiology. - : S. Karger AG. - 0302-282X .- 1423-0224. ; 57:1-2, s. 14-21
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Tidskriftsartikel (refereegranskat)abstract
- <i>Background/Aims:</i> Recent results indicate a role of the hypothalamic-pituitary-adrenal (HPA) axis in the pathophysiology of obsessive-compulsive disorder (OCD). Although childhood onset is common, the HPA axis has scarcely been studied in young OCD subjects. Therefore, the present study aimed at examining basal and response levels of salivary cortisol in a sample of young OCD subjects. <i>Methods:</i> Twenty-three children and adolescents with DSM-IV OCD were compared to a reference group of school children (n = 240–336). The basal cortisol rhythm was measured through saliva samples 3 times/day. The cortisol response to a psychological stressor (exposure therapy in the OCD group and a fire alarm in the reference group) was also examined. <i>Results:</i> Compared to the reference group, OCD subjects displayed higher early-morning cortisol values (p = 0.005) with no difference between the late-morning and evening values. The cortisol levels in the OCD group diminished in response to the psychological stressor, compared to a positive response in the reference group (p < 0.001). No relation was found between cortisol and clinical parameters. <i>Conclusion:</i> These results support the idea that HPA hyperactivity, commonly found in adult OCD patients, is also present at an earlier stage of development, with specificity for the early-morning peak.
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| 4. |
- Gustafsson, Per E, 1981-
(författare)
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Psychosocial Stress, Mental Health and Salivary Cortisol in Children and Adolescents
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stressful experiences and conditions in childhood influence the health and well-being of the growing individual, and can also confer a long-lasting impact into adult life. Delineating the social, mental and biological aspects of stress in children and adolescents is therefore of great concern for human beings. Despite these notions, much knowledge is lacking regarding stress in childhood.This thesis aimed at examining diverse aspects of stress in children and adolescents: associations between social conditions, traumatic life events, mental health, and salivary cortisol as a measure of the activity of a major physiological stress system. Cross-sectional samples included two non-clinical samples of school-aged children (N=240-336) and adolescents (N =400), and two clinical samples of children with obsessive-compulsive disorder (OCD) (N =23) and adolescents who had experienced childhood abuse (N =15). Main measures were salivary cortisol sampled three times a day, and questionnaires to teachers, parents and children with questions about each child’s mental health, traumatic life events and about the socioeconomic situation of the parents.The main findings include observation of 1) higher cortisol levels in children with a moderate level of psychosocial burden (low socioeconomic status, immigrant family, social impairment of mental health problems), 2) higher cortisol levels in children with OCD who also displayed a tendency to decreasing cortisol in the face of an acute stressor, and 3) cortisol was positively related to mental health problems in abused adolescents. Furthermore, the deleterious effect of 4) traumatic events involving a social dimension, interpersonal traumas, and 5) cumulative traumatic events, polytraumatization, on the mental health of children and adolescents was indicated.The findings are discussed with respect to the complex interactions between social, mental and biological aspects of children and adolescents. The consequences of adverse experiences in childhood may represent pathways to future health problems. Consideration of the social circumstances in childhood might in the future guide public health policies and the identification of target groups for preventive interventions as well as leading to improvements in treatment for children exposed to severe stress.
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| 5. |
- Gustafsson, Per E., 1981-, et al.
(författare)
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Sociocultural Disadvantage, Traumatic Life Events, and Psychiatric Symptoms in Preadolescent Children
- 2009
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Ingår i: American Journal of Orthopsychiatry. - : American Psychological Association (APA). - 0002-9432 .- 1939-0025. ; 79:3, s. 387-397
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has demonstrated impact of psychosocial adversity on the mental health of children. This cross-sectional study examined the differential relationships between life-time exposure to interpersonal and non-interpersonal traumatic life events as well as sociocultural factors (family social class and immigrant family), and the level of externalizing versus internalizing symptoms. Participants included 258 children aged 6 to 12 years from two Swedish elementary schools. Information was obtained from their parents by means of questionnaires (a demographic form including information about parental occupation and country of origin, the Strengths and Difficulties Questionnaire and the Life Incidence of Traumatic Events checklist). While controlling for gender, age and the other symptom dimension, the sociocultural factors were associated to internalizing but not to externalizing symptoms. In contrast, traumatic life events and especially interpersonal traumas related to externalizing symptoms but not to internalizing symptoms. These findings provide some support for specificity of psychosocial adversities and for the importance of interpersonal traumas, in the impact on child mental health.
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| 6. |
- Bargholtz, Chr., et al.
(författare)
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Measurement of the eta -> pi(+)pi(-)e(+)e(-) decay branching ratio
- 2007
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 644:5-6, s. 299-303
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Tidskriftsartikel (refereegranskat)abstract
- The reaction pd -> He-3 eta at threshold was used to provide a clean source of eta mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay eta -> pi(+)pi(-)e(+)e(-) is measured to be (4.3 +/- 1.3 +/- 0.4) x 10(-4).
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| 7. |
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| 8. |
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| 9. |
- Ihre, E, et al.
(författare)
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Early rise in exhaled nitric oxide and mast cell activation in repeated low-dose allergen challenge
- 2006
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Ingår i: European Respiratory Journal. - : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 27:6, s. 1152-9
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Tidskriftsartikel (refereegranskat)abstract
- Repeated low-dose allergen inhalation challenge mimics natural allergen exposure, providing a model for early mechanisms in the triggering of asthma. The current authors performed a controlled study to evaluate the time course of changes in exhaled nitric oxide fraction (F(e,NO)) and urinary biomarkers of airway inflammation. Eight subjects with mild allergic asthma completed two 7-day repeated low-dose challenge periods, with diluent and allergen, respectively. Subjects were symptom free at inclusion and were investigated when not exposed to specific allergen. Pulmonary function and symptoms were followed, and F(e,NO) and urinary mediators were correlated to changes in airway responsiveness to histamine and adenosine. Despite no change in pulmonary function (forced expiratory volume in one second mean+/-sem fall 0.3+/-0.7 versus 0.6+/-1.0%, for diluent and allergen, respectively) and no asthma symptoms, repeated allergen exposure, in contrast to diluent, caused significant increases in histamine responsiveness (2.3 doubling doses), an early and gradual increase in F(e,NO) (up to a doubling from baseline) and a small increase in the mast cell marker 9alpha11beta-prostaglandin F(2) after adenosine challenge. In conclusion, serial measurements of exhaled nitric oxide fraction have the potential to provide a very sensitive strategy for early detection of emerging airway inflammation and subsequent changes in airway hyperresponsiveness to histamine.
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| 10. |
- Agvald, Per, et al.
(författare)
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Increased expired NO and roles of CO2 and endogenous NO after venous gas embolism in rabbits
- 2006
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Ingår i: European Journal of Applied Physiology. - Heidelberg, Germany : Springer Berlin/Heidelberg. - 1439-6319 .- 1439-6327. ; 97:2, s. 210-215
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Tidskriftsartikel (refereegranskat)abstract
- Venous gas embolism (VGE) is a feared complication in diving, aviation, surgery and trauma. We hypothesized that air emboli in the lung circulation might change expired nitric oxide (FeNO). A single intravenous infusion of air was given (100 mul kg(-1)) to three groups of anaesthetized mechanically ventilated rabbits: (A) one with intact NO production, (B) one with intact NO production and where end-tidal CO(2) was controlled, and (C) one with endogenous NO synthesis blockade (L: -NAME, 30 mg kg(-1)). Air infusions resulted in increased FeNO of the control group from 20 (4) [mean (SD)] ppb to a peak value of 39 (4) ppb within 5 min (P < 0.05), and FeNO was still significantly elevated [27 (2) ppb] after 20 min (P < 0.05). Parallel to the NO increase there were significant decreases in end-tidal CO(2 )(ETCO(2)) and mean arterial pressure and an increase in insufflation pressure. In group B, when CO(2) was supplemented after air infusion, NO was suppressed (P = 0.033), but was still significantly elevated compared with pre-infusion control (P < 0.05). In group C, all animals died within 40 min of air infusion whereas all animals in the other groups were still alive at this time point. We conclude that venous air embolization increases FeNO, and that a part of this effect is due to the concomitant decrease in ETCO(2). Furthermore, an intact NO production may be critical for the tolerance to VGE. Finally, FeNO might have a potential in the diagnosis and monitoring of pulmonary gas embolism.
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