23 research outputs found

    Categorial L\'evy Processes

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    We generalize Franz' independence in tensor categories with inclusions from two morphisms (which represent generalized random variables) to arbitrary ordered families of morphisms. We will see that this only works consistently if the unit object is an initial object, in which case the inclusions can be defined starting from the tensor category alone. The obtained independence for morphisms is called categorial independence. We define categorial L\'evy processes on every tensor category with initial unit object and present a construction generalizing the reconstruction of a L\'evy process from its convolution semigroup via the Daniell-Kolmogorov theorem. Finally, we discuss examples showing that many known independences from algebra as well as from (noncommutative) probability are special cases of categorial independence.Comment: Changes in v2: Abstract and introduction extended. Background on tensor functors moved to Section 2. Example section extended and reorganized. References updated. Acknowledgements updated. (Some Enrivonment numbers have changed!

    Sequential treatment of ADHD in mother and child (AIMAC study): importance of the treatment phases for intervention success in a randomized trial

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    Background: The efficacy of parent-child training (PCT) regarding child symptoms may be reduced if the mother has attention-deficit/hyperactivity disorder (ADHD). The AIMAC study (ADHD in Mothers and Children) aimed to compensate for the deteriorating effect of parental psychopathology by treating the mother (Step 1) before the beginning of PCT (Step 2). This secondary analysis was particularly concerned with the additional effect of the Step 2 PCT on child symptoms after the Step 1 treatment. Methods: The analysis included 143 mothers and children (aged 6–12 years) both diagnosed with ADHD. The study design was a two-stage, two-arm parallel group trial (Step 1 treatment group [TG]: intensive treatment of the mother including psychotherapy and pharmacotherapy; Step 1 control group [CG]: supportive counseling only for mother; Step 2 TG and CG: PCT). Single- and multi-group analyses with piecewise linear latent growth curve models were applied to test for the effects of group and phase. Child symptoms (e.g., ADHD symptoms, disruptive behavior) were rated by three informants (blinded clinician, mother, teacher). Results: Children in the TG showed a stronger improvement of their disruptive behavior as rated by mothers than those in the CG during Step 1 (Step 1: TG vs. CG). In the CG, according to reports of the blinded clinician and the mother, the reduction of children’s disruptive behavior was stronger during Step 2 than during Step 1 (CG: Step 1 vs. Step 2). In the TG, improvement of child outcome did not differ across treatment steps (TG: Step 1 vs. Step 2). Conclusions: Intensive treatment of the mother including pharmacotherapy and psychotherapy may have small positive effects on the child’s disruptive behavior. PCT may be a valid treatment option for children with ADHD regarding disruptive behavior, even if mothers are not intensively treated beforehand. Trial registration: ISRCTN registry ISRCTN73911400. Registered: 29 March 2007

    Microscopic Understanding of Reaction Rates Observed in Plasmon Chemistry of Nanoparticle–Ligand Systems

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    Surface-enhanced Raman scattering (SERS) is an effective and widely used technique to study chemical reactions induced or catalyzed by plasmonic substrates, since the experimental setup allows us to trigger and track the reaction simultaneously and identify the products. However, on substrates with plasmonic hotspots, the total signal mainly originates from these nanoscopic volumes with high reactivity and the information about the overall consumption remains obscure in SERS measurements. This has important implications; for example, the apparent reaction order in SERS measurements does not correlate with the real reaction order, whereas the apparent reaction rates are proportional to the real reaction rates as demonstrated by finite-difference time-domain (FDTD) simulations. We determined the electric field enhancement distribution of a gold nanoparticle (AuNP) monolayer and calculated the SERS intensities in light-driven reactions in an adsorbed self-assembled molecular monolayer on the AuNP surface. Accordingly, even if a high conversion is observed in SERS due to the high reactivity in the hotspots, most of the adsorbed molecules on the AuNP surface remain unreacted. The theoretical findings are compared with the hot-electron-induced dehalogenation of 4-bromothiophenol, indicating a time dependency of the hot-carrier concentration in plasmon-mediated reactions. To fit the kinetics of plasmon-mediated reactions in plasmonic hotspots, fractal-like kinetics are well suited to account for the inhomogeneity of reactive sites on the substrates, whereas also modified standard kinetics model allows equally well fits. The outcomes of this study are on the one hand essential to derive a mechanistic understanding of reactions on plasmonic substrates by SERS measurements and on the other hand to drive plasmonic reactions with high local precision and facilitate the engineering of chemistry on a nanoscale

    Negative parenting behaviour as a mediator of the effects of telephone-assisted self-help for parents of pharmacologically treated children with attention-deficit/hyperactivity disorder

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    A previous randomised controlled trial demonstrated the effects of a telephone-assisted self-help (TASH) intervention for parents of pharmacologically treated children with attention-deficit/hyperactivity disorder (ADHD) on ADHD symptoms, oppositional symptoms, functional impairment, and negative parenting behaviour (per-protocol analyses). In the current study, we examined whether changes in positive and negative parenting behaviour mediated the effects on symptoms and impairment. Parents in an enhancement group (n = 51) participated in a 12-month TASH intervention (eight booklets plus up to 14 telephone consultations) as an adjunct to routine clinical care, whereas parents in a waitlist control group (n = 52) received routine clinical care only. Parents completed measures of child symptoms, child functional impairment, and parenting behaviour at baseline, at 6 months, and at 12 months. The mediating effects of parenting behaviour were examined using regression analyses. Per-protocol analyses (n = 74) revealed a significant indirect intervention effect on functional impairment through negative parenting behaviour at 6 months as well as indirect intervention effects on oppositional symptoms and functional impairment through negative parenting behaviour at 12 months. The indirect effect on ADHD symptoms through negative parenting behaviour at 12 months just failed to reach significance. The analyses yielded no indirect intervention effects through positive parenting behaviour. The study provides some, albeit limited, support for the importance of changes in negative parenting behaviour to achieve changes in symptoms and functional impairment during parent training. In consideration of the inconsistent results of previous studies concerning the mediating role of positive and negative parenting behaviour, further research is required to better understand the mechanisms of change during parent training, also including other possible mediators like parenting stress and parental self-efficacy

    Predicting delinquent behavior in young adults with a childhood diagnosis of ADHD: results from the Cologne Adaptive Multimodal Treatment (CAMT) Study

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    The aim of this study was to investigate which factors predict lifetime reports of delinquent behavior in young adults who had received adaptive multimodal treatment of attention-deficit/hyperactivity disorder (ADHD) starting at ages 6-10 years. Participants were reassessed 13-24 years (M = 17.6, SD = 1.8) after they had received individualized ADHD treatment in the Cologne Adaptive Multimodal Treatment Study (CAMT). Their behavior was classified as non-delinquent (n = 34) or delinquent (n = 25) based on self-reports regarding the number of police contacts, offenses, and convictions at follow-up. Childhood variables assessed at post-intervention (e.g., externalizing child behavior problems, intelligence, and parenting behavior) that were significantly associated with group membership were entered as possible predictors of delinquency in a Chi-squared automatic interaction detector (CHAID) analysis. Delinquent behavior during adolescence and adulthood was best predicted by (a) meeting the symptom count diagnostic criteria for conduct disorder (CD) according to parent ratings, in combination with a nonverbal intelligence of IQ <= 106 at post-intervention, and (b) delinquent behavior problems (teacher rating) at post-intervention. The predictor variables specified in the CHAID analysis classified 81% of the participants correctly. The results support the hypothesis that a childhood diagnosis of ADHD is only predictive of delinquent behavior if it is accompanied by early conduct behavior problems. Low nonverbal intelligence was found to be an additional risk factor. These findings underline the importance of providing behavioral interventions that focus on externalizing behavior problems to children with ADHD and comorbid conduct problems

    Kinetics and Mechanism of Plasmon-Driven Dehalogenation Reaction of Brominated Purine Nucleobases on Ag and Au

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    Plasmon-driven photocatalysis is an emerging and promising application of noble metal nanoparticles (NPs). An understanding of the fundamental aspects of plasmon interaction with molecules and factors controlling their reaction rate in a heterogeneous system is of high importance. Therefore, the dehalogenation kinetics of 8-bromoguanine (BrGua) and 8-bromoadenine (BrAde) on aggregated surfaces of silver (Ag) and gold (Au) NPs have been studied to understand the reaction kinetics and the underlying reaction mechanism prevalent in heterogeneous reaction systems induced by plasmons monitored by surface enhanced Raman scattering (SERS). We conclude that the time-average constant concentration of hot electrons and the time scale of dissociation of transient negative ions (TNI) are crucial in defining the reaction rate law based on a proposed kinetic model. An overall higher reaction rate of dehalogenation is observed on Ag compared with Au, which is explained by the favorable hot-hole scavenging by the reaction product and the byproduct. We therefore arrive at the conclusion that insufficient hole deactivation could retard the reaction rate significantly, marking itself as rate-determining step for the overall reaction. The wavelength dependency of the reaction rate normalized to absorbed optical power indicates the nonthermal nature of the plasmon-driven reaction. The study therefore lays a general approach toward understanding the kinetics and reaction mechanism of a plasmon-driven reaction in a heterogeneous system, and furthermore, it leads to a better understanding of the reactivity of brominated purine derivatives on Ag and Au, which could in the future be exploited, for example, in plasmon-assisted cancer therapy
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