Des conduites à risques aux assuétudes comportementales : le trouble addictif au danger

Several studies show that playing a dangerous sport has a direct influence on the emotional state of athletes. Engaging in such behaviour would not only reduce negative affect but also produce a positive affect that does not equate only relief but an “extraordinary experienced”. Notwithstanding the unique qualities of these sports, it is likely that some subclinical individual characteristics such as sensation seeking, emotional–behavioural deregulation can promote a self-reinforcement of these practices or even facilitated the installation of an addictive tendency. Risk and intense sensation are also at the heart of dangerous games. Four points seem to motivate these practices: risk-taking, intensity, loss of consciousness, and the “wake survival”. In addition, practitioners are characterized by a more severe depressive symptomatology than non-practitioners. Some of these depressive elements are probably anterior to the game, but it is also possible that others are the consequence; this has the effect of strengthening the emotional–behavioural addiction. Through these extreme sports and games of non-oxygenation, the level of danger appears to be a real source of excitement. Playing with death is going to give inner magnitude to the experience. Without the sense of risk, the practice of the activity would not make sense. Psychological functioning of these sports and these “players” is based on the need to be stimulated, to be excited by the risk or even the fear in order to be appeased. Also, treat the danger, but also and mainly deal with emotions. The danger as a means of activation may fill in a toxic function of emotional and behavioural self-regulation including a risk that this excitation will self-sustained. Indeed, some of these athletes and these “players” increase their practice and push the safety threshold by adopting behaviours more and more risky in order to experiment higher sensations. When some semiological clues characterize the practice of risky activities like the repetition of a dangerous situation, loss of control, the invasion of the psychic life, time spent at the expense of social, family and school activities… they may reflect a real addiction to danger. It therefore becomes necessary for the clinician and the researcher to identify all these prodromal symptoms and signs of addiction. Criteria for the diagnosis of Addictive Disorder to Danger are proposed and discussed.     

A Constrained Linear Estimator for Multiple Regression

“Improper linear models” (see Dawes, Am. Psychol. 34:571–582, 1979), such as equal weighting, have garnered interest as alternatives to standard regression models. We analyze the general circumstances under which these models perform well by recasting a class of “improper” linear models as “proper” statistical models with a single predictor. We derive the upper bound on the mean squared error of this estimator and demonstrate that it has less variance than ordinary least squares estimates. We examine common choices of the weighting vector used in the literature, e.g., single variable heuristics and equal weighting, and illustrate their performance in various test cases.     

Physical Oracles: The Turing Machine and the Wheatstone Bridge

Earlier, we have studied computations possible by physical systems and by algorithms combined with physical systems. In particular, we have analysed the idea of using an experiment as an oracle to an abstract computational device, such as the Turing machine. The theory of composite machines of this kind can be used to understand (a) a Turing machine receiving extra computational power from a physical process, or (b) an experimenter modelled as a Turing machine performing a test of a known physical theory T. Our earlier work was based upon experiments in Newtonian mechanics. Here we extend the scope of the theory of experimental oracles beyond Newtonian mechanics to electrical theory. First, we specify an experiment that measures resistance using a Wheatstone bridge and start to classify the computational power of this experimental oracle using non-uniform complexity classes. Secondly, we show that modelling an experimenter and experimental procedure algorithmically imposes a limit on our ability to measure resistance by the Wheatstone bridge. The connection between the algorithm and physical test is mediated by a protocol controlling each query, especially the physical time taken by the experimenter. In our studies we find that physical experiments have an exponential time protocol; this we formulate as a general conjecture. Our theory proposes that measurability in Physics is subject to laws which are co-lateral effects of the limits of computability and computational complexity.     

Serious,Minor, and Non-Delinquents in Early Adolescence: The Impact of Cumulative Risk and Promotive Factors. The TRAILS Study

This study uses a social-ecological approach to the development of delinquency. The authors emphasize that a balance between eliminating risk and enhancing protection across domains is essential in reducing problems and promoting competence. The cumulative risk and promotive effects of temperament, family and school factors in preadolescence were examined on different groups of delinquents (based on self-report) in early adolescence. Data from the first two waves of the TRAILS study (N = 2,230) were used. The results provide evidence for a compensatory model that assumes main effects of risk and promotive factors on problem behavior. Accumulation of risks in preadolescence promoted being a serious delinquent in early adolescence, with the strongest effects for temperament. Accumulation of promotive effects decreased being a delinquent and supported being a non-delinquent. Furthermore, evidence is found for a counter-balancing effect of cumulative promotive and risk factors. Exposure to more promotive domains in the relative absence of risk domains decreased the percentage of serious delinquents. Our results did not support a protective model. Implications for prevention and intervention are discussed.     

On the Speed Sensitivity Parameter in the Lognormal Model for Response Times and Implications for High-Stakes Measurement Practice

In high-stakes testing, often multiple test forms are used and a common time limit is enforced. Test fairness requires that ability estimates must not depend on the administration of a specific test form. Such a requirement may be violated if speededness differs between test forms. The impact of not taking speed sensitivity into account on the comparability of test forms regarding speededness and ability estimation was investigated. The lognormal measurement model for response times by van der Linden was compared with its extension by Klein Entink, van der Linden, and Fox, which includes a speed sensitivity parameter. An empirical data example was used to show that the extended model can fit the data better than the model without speed sensitivity parameters. A simulation was conducted, which showed that test forms with different average speed sensitivity yielded substantial different ability estimates for slow test takers, especially for test takers with high ability. Therefore, the use of the extended lognormal model for response times is recommended for the calibration of item pools in high-stakes testing situations. Limitations to the proposed approach and further research questions are discussed.     

Short-range order in the arrangement of grains in two-dimensional polycrystals

Abstract

Experimental results for two-dimensional grain growth are compared with the results obtained from computer-generated random threefold vertex networks with a fixed one-particle distribution function. A considerable discrepancy in the two-particle distributions implies some kind of short-range order. New results in the computer simulation of normal grain growth are reported, demonstrating a similar kind of ordering. A simple relation is suggested for the quantity m _n, introduced by Aboav and the second moment of the one-particle distribution μ₂     

Chemical diffusion by vacancy pairs in intermetallic compounds with the B2 structure

This paper is concerned with the implications of vacancy-pair mechanisms on chemical diffusion in intermetallic compounds with the B2 structure. The discussion specifically includes the so-called triple-defect mechanism. It is shown that the vacancy-pair mechanism cannot contribute to chemical diffusion in the intermetallic compound at the stoichiometric composition AB. Focusing on the triple-defect mechanism we extend it to non-stoichiometric compositions by including isolated antistructural atoms. By means of Monte Carlo simulation we show that the efficiency of the triple-defect mechanism in providing for chemical diffusion increases linearly with increasing antistructural atom composition but the efficiency remains relatively low unless the composition is highly non-stoichiometric.     

Public Storylines in the British Transition from Rail to Road Transport (1896–2000): Discursive Struggles in the Multi-Level Perspective

ABSTRACT

An analysis of the transition from railways to highways as the dominant British transport system during the twentieth century shows that public storylines about competing niche and regime technologies can have a powerful influence on socio-technical transitions. These storylines are developed by supporters and opponents of the competing technologies, with each group attempting to frame their favoured technology positively. The public salience of these storylines can be evaluated by assessing how highly they score on four elements of frame resonance: empirical fit, experiential commensurability, actor credibility, and macro-cultural resonance. These storylines can be seen at play across the entirety of the transition to a road-based transport system, from the very early history of the automobile through to the turn of the millennium, when public opposition to road transport was becoming increasingly pronounced. This case study uniquely traces discursive conflict over the entire course of a multi-decade transition. While existing literature in the multi-level perspective typically emphasises the disadvantages faced by niche-innovations, this case study shows that powerful storylines, enabled by the right cultural repertoires and possibly negative storylines about existing socio-technical systems, can create powerful political support for a new technology, giving it an advantage against more established incumbents.     

Comments on Monte Carlo simulations of void-lattice formation

We study the coalescence of neighbouring voids along close-packed directions in recent computer simulation studies of void-lattice formation. The stability against coalescence of a developing void lattice is found to depend very much on the detailed geometry of the local void distribution. The possibility of void coalescence as an artifact, caused by the incorrect assumption of homogeneous void nucleation in these simulations, is suggested and discussed.     

Kinetics of photoinduced changes in Ag nanoparticles deposited on an indium tin oxide surface

An enhancement of the UV-visible optical absorption spectra of Ag nanoparticles (NPs) deposited on indium tin oxide (ITO) surfaces of different resistance by a seed-mediated growth technique is presented. A bicolour coherent beam, obtained from a pulsed Nd:YAG laser providing a 1060-nm fundamental wavelength and a double-frequency one at 530?nm, was used. A significant change in the optical density is observed for Ag NPs on low-resistance ITO surfaces (≈4?Ω/square), while almost nothing occurs with high-resistance (≈50?Ω/square surfaces). The spectral position of the maximal absorption at 440?nm is almost preserved in both cases. This result is explained in terms of a local photoinduced static field and surface-plasmon polaritons interacting with photoexcited phonons. A grating effect, arising from the coherent bicolour light forming a superstructure as for quantum crystals, could be another contribution.