The Netherlands

This chapter describes the background of the Communities That Care strategy in the Netherlands and the results of the Communities That Care Youth Survey. This was administered in 2011 as part of an effect study which was going on at that time. In this chapter we studied violence and youth delinquency, other problem behaviours, 20 risk factors and 10 protective factors, for 5887 youngsters. We show their scores on violent and delinquent acts, the prevalences of other problem behaviours and their associations. We also researched the association between violence and delinquency and the risk and protective factors in the domains of family, school, friends and community. With the use of logistic regression and odds ratios, possible effects are detected. We also used the population attributable fraction as a measure of exposure explained by risk factors and protective factors. In the third and last part, we researched the cumulative effect of the risk and protective factors when they are clustered together. This chapter confirms what we already know about problem behaviours and their predictors but throws fresh light on it. This chapter shows how violence and delinquency can be targeted by social policy and prevention

Sleep Physiology, Circadian Rhythms, Waking Performance and the Development of Sleep-Wake Therapeutics

Disturbances of the sleep-wake cycle are highly prevalent and diverse. The aetiology of some sleep disorders, such as circadian rhythm sleep-wake disorders, is understood at the conceptual level of the circadian and homeostatic regulation of sleep and in part at a mechanistic level. Other disorders such as insomnia are more difficult to relate to sleep regulatory mechanisms or sleep physiology. To further our understanding of sleep-wake disorders and the potential of novel therapeutics, we discuss recent findings on the neurobiology of sleep regulation and circadian rhythmicity and its relation with the subjective experience of sleep and the quality of wakefulness. Sleep continuity and to some extent REM sleep emerge as determinants of subjective sleep quality and waking performance. The effects of insufficient sleep primarily concern subjective and objective sleepiness as well as vigilant attention, whereas performance on higher cognitive functions appears to be better preserved albeit at the cost of increased effort. We discuss age-related, sex and other trait-like differences in sleep physiology and sleep need and compare the effects of existing pharmacological and non-pharmacological sleep- and wake-promoting treatments. Successful non-pharmacological approaches such as sleep restriction for insomnia and light and melatonin treatment for circadian rhythm sleep disorders target processes such as sleep homeostasis or circadian rhythmicity. Most pharmacological treatments of sleep disorders target specific signalling pathways with no well-established role in either sleep homeostasis or circadian rhythmicity. Pharmacological sleep therapeutics induce changes in sleep structure and the sleep EEG which are specific to the mechanism of action of the drug. Sleep- and wake-promoting therapeutics often induce residual effects on waking performance and sleep, respectively. The need for novel therapeutic approaches continues not at least because of the societal demand to sleep and be awake out of synchrony with the natural light-dark cycle, the high prevalence of sleep-wake disturbances in mental health disorders and in neurodegeneration. Novel approaches, which will provide a more comprehensive description of sleep and allow for large-scale sleep and circadian physiology studies in the home environment, hold promise for continued improvement of therapeutics for disturbances of sleep, circadian rhythms and waking performance

A solution study of silica condensation and speciation with relevance to in vitro investigations of biosilicification

Requiring mild synthesis conditions and possessing a high level of organization and functionality, biosilicas constitute a source of wonder and inspiration for both materials scientists and biologists. In order to understand how such biomaterials are formed and to apply this knowledge to the generation of novel bioinspired materials, a detailed study of the materials, as formed under biologically relevant conditions, is required. In this contribution, data from a detailed study of silica speciation and condensation using a model bioinspired silica precursor (silicon catechol complex, SCC) is presented The silicon complex quickly and controllably dissociates under neutral pH conditions to well-defined, metastable solutions of orthosilicic acid The formation of silicomolybdous (blue) complexes was used to monitor and study different stages of silicic acid condensation In parallel, the rates of silicomolybdic (yellow) complex formation, with mathematical modeling of the species present, was used to follow the solution speciation of polysilicic acids. The results obtained from the two assays correlate well. Monomeric Oleic acid, trimeric silicic acids, and different classes of oligomenc polysilicic acids and silica nuclei can be identified and their periods of stability during the early stages of silica condensation measured For experiments performed at a range of temperatures (273-323 K), an activation energy of 77 kJ.mol(-1) was obtained for the formation of trimers. The activation energies for the forward and reverse condensation reactions for addition of monomers to polysilicic acids (273-293 +/- 1 K) were 55.0 and 58.6 kJ.mol(-1), respectively. For temperatures above 293 K, these energies were reduced to 6 1 and 7.3 kJ.mol(-1), indicating a probable change in the prevailing condensation mechanism The impact of pH on the rates of condensation were measured There was a direct correlation between the apparent third-order rate constant for trimer formation and pH (4.7-6.9 +/- 0.1) while values for the reversible first-order rates reached a plateau at circumneutral pH. These different behaviors are discussed with reference to the generally accepted mechanism for silica condensation in which anionic silicate solution species are central to the condensation process. The results presented in this paper support the use of precursors such as silicon catecholate complexes in the study of biosilicification in vitro Further detailed experimentation is needed to increase our understanding of specific biomolecule silica interactions that ultimately generate the complex, finely detailed siliceous structures we observe in the world around us