Adolescence methamphetamine use is an issue of considerable concern due to its correlation with later delinquency, divorce, unemployment and health problems. Understanding how adolescents initiate methamphetamine abuse is important in developing effective prevention programs. We formulate a mathematical model for the spread of methamphetamine abuse using nonlinear ordinary differential equations. It is assumed that susceptibles are recruited into methamphetamine use through imitation. An epidemic threshold value, Ra\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal {R}}_a$$\end{document}, termed the abuse reproduction (...) number, is proposed and defined herein in the drug-using context. The model is shown to exhibit the phenomenon of backward bifurcation. This means that methamphetamine problems may persist in the population even if Ra\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal {R}}_a$$\end{document} is less than one. Sensitivity analysis of Ra\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal {R}}_a$$\end{document} was performed to determine the relative importance of different parameters in methamphetamine abuse initiation. The model is then fitted to data on methamphetamine users less than 20 years old reporting methamphetamine as their primary substance of abuse in the treatment centres of Cape Town and parameter values that give the best fit are chosen. Results show that the proportion of methamphetamine users less than 20 years old reporting methamphetamine as their primary substance of abuse will continue to decrease in Cape Town of South Africa. The results suggest that intervention programs targeted at reducing adolescence methamphetamine abuse, are positively impacting methamphetamine abuse. (shrink)

The phenomenon of probability backflow, previously quantified for a free nonrelativistic particle, is considered for a free particle obeying Dirac's equation. It is shown that probability backflow can occur in the opposite direction to the momentum; that is to say, there exist positive-energy states in which the particle certainly has a positive momentum in a given direction, but for which the component of the probability flux vector in that direction is negative. It is shown that the maximum possible amount of (...) probability that can flow “backwards,” over a given time interval of duration T, depends on the dimensionless parameter ε = (4ℏ/mc2T)1/2, where m is the mass of the particle and c is the speed of light. At ε = 0, the nonrelativistic value of approximately 0.039 for this maximum is recovered. Numerical studies suggest that the maximum decreases monotonically as ε increases from 0, and show that it depends on the size of m, ℏ, and T, unlike the nonrelativistic case. (shrink)

Payment for research participation has raised ethical concerns, especially with respect to its potential for coercion. We argue that characterising payment for research participation as coercive is misguided, because offers of benefit cannot constitute coercion. In this article we analyse the concept of coercion, refute mistaken conceptions of coercion and explain why the offer of payment for research participation is never coercive but in some cases may produce undue inducement.

But a body of rigorous mathematical theory has also gradually developed, and this is the first book to present that theory.

Context Physicians are regularly confronted with research that is funded or presented by industry. Objective To assess whether physicians discount for conflicts of interest when weighing evidence for prescribing a new drug. Design and setting Participants were presented with an abstract from a single clinical trial finding positive results for a fictitious new drug. Physicians were randomly assigned one version of a hypothetical scenario, which varied on conflict of interest: ‘presenter conflict’, ‘researcher conflict’ and ‘no conflict’. Participants 515 randomly selected (...) Fellows in the American College of Obstetricians and Gynecologists' Collaborative Ambulatory Research Network; 253 surveys (49%) were returned. Main object measures The self-reported likelihood that physicians would prescribe the new drug as a first-line therapy. Results Physicians do not significantly discount for conflicts of interest in their self-reported likelihood of prescribing the new drug after reading the single abstract and scenario. However, when asked explicitly to compare conflict and no conflict, 69% report that they would discount for researcher conflict and 57% report that they would discount for presenter conflict. When asked to guess how favourable the results of this study were towards the new drug, compared with the other trials published so far, their perceptions were not significantly influenced by conflict of interest information. Conclusion While physicians believe that they should discount the value of information from conflicted sources, they did not do so in the absence of a direct comparison between two studies. This brings into question the effectiveness of merely disclosing the funding sources of published studies. (shrink)

John McMillan's article raises numerous important points about the ethics of surgical castration of sex offenders.1 In this commentary, we focus solely on and argue against the claim that the offer of release from detention conditional upon surgical castration is a coercive offer that compromises the validity of the offender's consent. We take no view on the question as to whether castration for sex offenders is ethically permissible. But, we reject the claim that it is ethically permissible only if competing (...) ethical considerations outweigh worries about coercion. For in the situation described, the proposal is not coercive at all.McMillan states that if offenders agree to castration because they fear long-term detention, then ‘it seems, intuitively, as if agreeing to be castrated under these conditions makes the decision coerced in some way.’1 He adds that if castration is ‘the only way that they will be released back into the community, the status of this decision as a genuine expression of their autonomy is questionable.’1 In defence of his claim, he uses two analogies that he borrows from Joel Feinberg. First, if a governor offers to commute a death sentence if the prisoner agrees to participate in a medical experiment, then ‘it's clear that the governor is coercing the prisoner.’1 Second, if a millionaire offers to give a woman $1 000 000 …. (shrink)

The current study explores how the cultural distance of ethnic outgroups relative to the ethnic ingroup is related to stereotypical news representations. It does so by drawing on a sample of more than three million Dutch newspaper articles and uses advanced methods of automated content analysis, namely word embeddings. The results show that distant ethnic outgroup members (i. e., Moroccans) are associated with negative characteristics and issues, while this is not the case for close ethnic outgroup members (i. e., Belgians). (...) The current study demonstrates the usefulness of word embeddings as a tool to study subtle aspects of ethnic bias in mass-mediated content. (shrink)

From a simple idea to unite asset owners in their quest for responsible investment at its launch in April 2006, the United Nations supported Principles for Responsible Investment have grown in just one decade into an initiative with more than 1500 fee-paying signatories. Jointly, the PRI’s signatories hold assets worth more than $80 trillion, making it one of the more prevalent not-for-profit organizations worldwide. Furthermore, the PRI’s ambitious mission to transform the financial system at large into a more sustainable one (...) makes it a worthwhile subject of inquiry from an institutional perspective. We undertake an empirical investigation of the adoption of the PRI by asset owners during five crucial years of the association’s emergence: 2007–2011. Following a tripartite view of institutional theory proposed by Scott, we explore if regulative, normative, and cultural–cognitive factors influence an asset owner’s decision to subscribe to the PRI. Applying both parametric and non-parametric survival analysis, we find that asset owners are indeed significantly affected by normative, cultural–cognitive, and regulative aspects. In particular, public service employee and labor union pension funds from social backgrounds more culturally aligned with values represented by the RI movement with historically more voluntary legislation on environmental, social, and governance issues are most likely to sign the PRI. In contrast, institutional environments with a higher number of pre-existing mandatory ESG regulation decrease the likelihood of signing the PRI. Our results indicate that normative and cultural–cognitive factors were crucial contributors to the PRI’s growth. With respect to the regulative environments, our results imply that some asset owners may use the PRI as a collective industry initiative to substitute for mandatory legislation. Conversely, a high level of historical mandatory legislation may constrain organizational resources that could otherwise be dedicated to voluntary initiatives such as PRI. Our findings are robust to relevant controls and econometric concerns. (shrink)

We review current theoretical cosmology, including fundamental and mathematical cosmology and physical cosmology (as well as cosmology in the quantum realm), with an emphasis on open questions.

Does action always arise out of desire? G. F. Schueler examines this hotly debated topic in philosophy of action and moral philosophy, arguing that once two senses of "desire" are distinguished - roughly, genuine desires and pro attitudes - apparently plausible explanations of action in terms of the agent's desires can be seen to be mistaken. Desire probes a fundamental issue in philosophy of mind, the nature of desires and how, if at all, they motivate and justify our actions. At (...) least since Hume argued that reason "is and of right ought to be the slave of the passions," many philosophers have held that desires play an essential role both in practical reason and in the explanation of intentional action. G. F. Schueler looks at contemporary accounts of both roles in various belief-desire models of reasons and explanation and argues that the usual belief-desire accounts need to be replaced. Schueler contends that the plausibility of the standard belief-desire accounts rests largely on a failure to distinguish "desires proper," like a craving for sushi, from so-called "pro attitudes," which may take the form of beliefs and other cognitive states as well as desires proper. Schueler's "deliberative model" of practical reasoning suggests a different view of the place of desire in practical reason and the explanation of action. He holds that we can arrive at an intention to act by weighing the relevant considerations and that these may not include desires proper at all. (shrink)

Listening to someone from some distance in a crowded room you may experience the following phenomenon: when looking at them speak, you may both hear and see where the source of the sounds is; but when your eyes are turned elsewhere, you may no longer be able to detect exactly where the voice must be coming from. With your eyes again fixed on the speaker, and the movement of her lips a clear sense of the source of the sound will (...) return. This ‘ventriloquist’ effect reflects the ways in which visual cognition can dominate auditory perception. And this phenomenological observation is one what you can verify or disconfirm in your own case just by the slightest reflection on what it is like for you to listen to someone with or without visual contact with them. (shrink)

In this paper I will argue that the latter group [of Non-Humeans] is correct. My argument focuses on practical deliberation and has two parts. I will discuss two different problems that arise for the Humean Theory and suggest that while taken individually each problem appears to have a solution, for each problem the solution Humeans offer precludes solving the other problem. I will suggest that to see these difficulties we must take seriously the thought that we can only understand an (...) agent’s reasons for her action by looking at her actual or possible practical deliberation. (shrink)