92 research outputs found
Low temperature magneto-morphological characterisation of coronene and the resolution of previously observed unexplained phenomena
The polyaromatic hydrocarbon coronene has been the molecule of choice for understanding the physical properties of graphene for over a decade. The modelling of the latter by the former was considered to be valid, as since it was first synthesised in 1932, the physical behaviour of coronene has been determined extremely accurately. We recently discovered however, an unforeseen polymorph of coronene, which exists as an enantiotrope with the previously observed crystal structure. Using low-temperature magnetisation and crystallographic measurements, we show here for the first time that the electronic and magnetic properties of coronene depend directly on the temperature at which it is observed, with hysteretic behaviour exhibited between 300 K and 100 K. Furthermore we determine that this behaviour is a direct result of the appearance and disappearance of the newly-discovered polymorph during thermal cycling. Our results not only highlight the need for theoretical models of graphene to take into account this anomalous behaviour at low temperatures, but also explain puzzling experimental observations of coronene dating back over 40 years
Facts, values, and Attention-Deficit Hyperactivity Disorder (ADHD): an update on the controversies
The Hastings Center, a bioethics research institute, is holding a series of 5 workshops to examine the controversies surrounding the use of medication to treat emotional and behavioral disturbances in children. These workshops bring together clinicians, researchers, scholars, and advocates with diverse perspectives and from diverse fields. Our first commentary in CAPMH, which grew out of our first workshop, explained our method and explored the controversies in general. This commentary, which grows out of our second workshop, explains why informed people can disagree about ADHD diagnosis and treatment. Based on what workshop participants said and our understanding of the literature, we make 8 points. (1) The ADHD label is based on the interpretation of a heterogeneous set of symptoms that cause impairment. (2) Because symptoms and impairments are dimensional, there is an inevitable "zone of ambiguity," which reasonable people will interpret differently. (3) Many other variables, from different systems and tools of diagnosis to different parenting styles and expectations, also help explain why behaviors associated with ADHD can be interpreted differently. (4) Because people hold competing views about the proper goals of psychiatry and parenting, some people will be more, and others less, concerned about treating children in the zone of ambiguity. (5) To recognize that nature has written no bright line between impaired and unimpaired children, and that it is the responsibility of humans to choose who should receive a diagnosis, does not diminish the significance of ADHD. (6) Once ADHD is diagnosed, the facts surrounding the most effective treatment are complicated and incomplete; contrary to some popular wisdom, behavioral treatments, alone or in combination with low doses of medication, can be effective in the long-term reduction of core ADHD symptoms and at improving many aspects of overall functioning. (7) Especially when a child occupies the zone of ambiguity, different people will emphasize different values embedded in the pharmacological and behavioral approaches. (8) Truly informed decision-making requires that parents (and to the extent they are able, children) have some sense of the complicated and incomplete facts regarding the diagnosis and treatment of ADHD
Developmental trajectories of child to adolescent externalizing behavior and adult DSM-IV disorder: results of a 24-year longitudinal study
Objective: Childhood externalizing behavior is found to be relatively persistent. Developmental pathways within types of externalizing behavior have been recognized from childhood to adolescence. We aimed to describe the prediction of adult DSM-IV disorders from developmental trajectories of externalizing behavior over a period of 24 years on a longitudinal multiple birth cohort study of 2,076 children. This has not been examined yet. Methods: Trajectories of the four externalizing behavior types aggression, opposition, property violations, and status violations were determined separately through latent class growth analysis (LCGA) using data of five waves, covering ages 4-18 years. Psychiatric disorders of 1,399 adults were assessed with the CIDI. We used regression analyses to determine the associations between children's trajectories and adults' psychiatric disorders. Results: All externalizing behavior types showed significant associations with disruptive disorder in adulthood. In all antisocial behavior types high-level trajectories showed the highest probability for predicting adult disorders. Particularly the status violations cluster predicted many disorders in adulthood. The trajectories most often predicted disruptive disorders in adulthood, but predicted also anxiety, mood, and substance use disorders. Conclusions: We can conclude that an elevated level of externalizing behavior in childhood has impact on the long-term outcome, regardless of the developmental course of externalizing behavior. Furthermore, different types of externalizing beh
Phenotypic Signatures Arising from Unbalanced Bacterial Growth
Fluctuations in the growth rate of a bacterial culture during unbalanced growth are generally considered undesirable in quantitative studies of bacterial physiology. Under well-controlled experimental conditions, however, these fluctuations are not random but instead reflect the interplay between intra-cellular networks underlying bacterial growth and the growth environment. Therefore, these fluctuations could be considered quantitative phenotypes of the bacteria under a specific growth condition. Here, we present a method to identify “phenotypic signatures” by time-frequency analysis of unbalanced growth curves measured with high temporal resolution. The signatures are then applied to differentiate amongst different bacterial strains or the same strain under different growth conditions, and to identify the essential architecture of the gene network underlying the observed growth dynamics. Our method has implications for both basic understanding of bacterial physiology and for the classification of bacterial strains
Prevalence of mental disorders from adolescence through early adulthood in American Indian and First Nations communities
Indigenous communities lack representation in psychiatric epidemiology despite disproportionate exposure to risk factors. We document the cumulative and 12-month prevalence of psychiatric disorders across the early life course among a sample of Indigenous young adults and compare prospective and retrospective reporting of lifetime mental disorders. This community-based participatory research includes data from 735 Indigenous people from 8 reservations/reserves. Personal interviews were conducted between 2002–2010 and 2017–2018 totaling 9 waves; diagnostic assessments of DSM-IV-TR alcohol abuse/dependence, marijuana use/dependence, other substance abuse/dependence, generalized anxiety disorder, major depressive disorder, dysthymic disorder, and attention deficit/hyperactivity disorder occurred at waves 1 (mean age = 11.1 years), 4 (mean age = 14.3 years), 6 (mean age = 16.2 years), 8 (mean age = 18.3 years), and 9 (mean age = 26.3 years). Cumulative lifetime psychiatric disorders reached 77.3% and lifetime comorbidity 56.4% by wave 9. Past-year prevalence and comorbidity at wave 9 were 28.7% and 6.7%, respectively. Substance use disorders (SUDs) were most common with peak past-year prevalence observed when participants were on average 16.3 years old then declining thereafter. Trends in early life course psychiatric disorders in this study with Indigenous participants highlight cultural variations in psychiatric epidemiology including surprisingly low rates of internalizing disorders in the face of risk factors, disproportionately high rates of early-onset and lifetime SUD, and lower rates of past-year SUD in early adulthood compared with prior research.Peer reviewedSociolog
Testing Developmental Pathways to Antisocial Personality Problems
This study examined the development of antisocial personality problems (APP) in young adulthood from disruptive behaviors and internalizing problems in childhood and adolescence. Parent ratings of 507 children’s (aged 6–8 years) symptoms of attention deficit hyperactivity disorder, oppositional defiant disorder, and anxiety, were linked to self-ratings of adolescents’ (aged 14–16 years) symptoms of depression, substance use, conduct problems, and somatic problems, to predict self-ratings of APP in young adulthood (age 20–22 years). The findings suggested a hierarchical development of antisocial behavior problems. Despite being positively associated with conduct problems in adolescence, neither internalizing problems nor substance use added to the prediction of APP in young adulthood from conduct problems in adolescence. The developmental pathways to APP in young adulthood did not differ by gender
Turner syndrome and sexual differentiation of the brain: implications for understanding male-biased neurodevelopmental disorders
Turner syndrome (TS) is one of the most common sex chromosome abnormalities. Affected individuals often show a unique pattern of cognitive strengths and weaknesses and are at increased risk for a number of other neurodevelopmental conditions, many of which are more common in typical males than typical females (e.g., autism and attention-deficit hyperactivity disorder). This phenotype may reflect gonadal steroid deficiency, haploinsufficiency of X chromosome genes, failure to express parentally imprinted genes, and the uncovering of X chromosome mutations. Understanding the contribution of these different mechanisms to outcome has the potential to improve clinical care for individuals with TS and to better our understanding of the differential vulnerability to and expression of neurodevelopmental disorders in males and females. In this paper, we review what is currently known about cognition and brain development in individuals with TS, discuss underlying mechanisms and their relevance to understanding male-biased neurodevelopmental conditions, and suggest directions for future research
Sports Participation and Juvenile Delinquency: A Meta-Analytic Review
Participation in sports activities is very popular among adolescents, and is frequently encouraged among youth. Many psychosocial health benefits in youth are attributed to sports participation, but to what extent this positive influence holds for juvenile delinquency is still not clear on both the theoretical and empirical level. There is much controversy on whether sports participation should be perceived as a protective or a risk factor for the development of juvenile delinquency. A multilevel meta-analysis of 51 published and unpublished studies, with 48 independent samples containing 431 effect sizes and N = 132,366 adolescents, was conducted to examine the relationship between sports participation and juvenile delinquency and possible moderating factors of this association. The results showed that there is no overall significant association between sports participation and juvenile delinquency, indicating that adolescent athletes are neither more nor less delinquent than non-athletes. Some study, sample and sports characteristics significantly moderated the relationship between sports participation and juvenile delinquency. However, this moderating influence was modest. Implications for theory and practice concerning the use of sports to prevent juvenile delinquency are discussed. Keywords Sports participation Juvenile delinquency Multilevel meta-analysis Revie
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