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)

Observations with respect to the relationship between symptoms and diseases can seriously be biased by selection phenomena. This selection may occur from the general population, via consultation behavior, diagnostic and therapeutic activities of the general practitioner, and by referral.Relationships may be suggested and reproduced even if they do not exist in unselected populations, as a product of diagnostic routines. Correction for selection bias can only be achieved by choosing proper comparison groups. While this can be done in a general practice (...) setting, this is almost impossible after referral, as is demonstrated in this paper. Surprisingly, the most unbiased estimation of the relationship between symptoms and diseases after referral can be made from patient groups that are referred for reason unrelated to the disease under study. (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)

First published in 2002. Routledge is an imprint of Taylor & Francis, an informa company.

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)

Primordial emotions are the subjective element of the instincts which are the genetically programmed behaviour patterns which contrive homeostasis. They include thirst, hunger for air, hunger for food, pain and hunger for specific minerals etc.There are two constituents of a primordial emotion—the specific sensation which when severe may be imperious, and the compelling intention for gratification by a consummatory act. They may dominate the stream of consciousness, and can have plenipotentiary power over behaviour.It is hypothesized that early in animal evolution (...) complex reflex mechanisms in the basal brain subserving homeostatic responses, in concert with elements of the reticular activating system subserving arousal, melded functionally with regions embodied in the progressive rostral development of the telencephalon. This included the emergent limbic and paralimbic areas, and the insula. This phylogenetically ancient organization subserved the origin of consciousness as the primordial emotion, which signalled that the organisms existence was immediately threatened. Neuroimaging confirms major activations in regions of the basal brain during primordial emotions in humans. The behaviour of decorticate humans and animals is discussed in relation to the possible existence of primitive awareness.Neuroimaging of the primordial emotions reveals that rapid gratification of intention by a consummatory act such as ingestion causes precipitate decline of both the initiating sensation and the intention. There is contemporaneous rapid disappearance of particular regions of brain activation which suggests they may be part of the jointly sufficient and severally necessary activations and deactivations which correlate with consciousness [Crick, F. & Koch, C. . A framework for consciousness. NatureNeuroscience,6, 119–126]. (shrink)

This volume presents new texts of Cicero's dialogues on political philosophy, De Re Publica and De Legibus, together with corrected versions of the editor's previously published editions of Cato Maior de Senectute and Laelius de Amicitia. The texts are based on a full reconsideration of the manuscript evidence and are presented in a clear and readable form.

Alonso-Meijide and Fiestras-Janeiro (2002, Annals of Operations Research 109, 213–227) proposed a modification of the Banzhaf value for games where a coalition structure is given. In this paper we present a method to compute this value by means of the multilinear extension of the game. A real-world numerical example illustrates the application procedure.

Interactive technology assessment (iTA) provides an answer to the ethical problem of normative bias in evaluation research. This normative bias develops when relevant perspectives on the evaluand (the thing being evaluated) are neglected. In iTA this bias is overcome by incorporating different perspectives into the assessment. As a consequence, justification of decisions based on the assessment is provided by stakeholders having achieved agreement. In this article, agreement is identified with wide reflective equilibrium to show that it indeed has the potential (...) of justifying decisions. We work out several conditions for this agreement to be achievable and just. (shrink)

The US neutrino community gathered at the Workshop on the Intermediate Neutrino Program at Brookhaven National Laboratory February 4-6, 2015 to explore opportunities in neutrino physics over the next five to ten years. Scientists from particle, astroparticle and nuclear physics participated in the workshop. The workshop examined promising opportunities for neutrino physics in the intermediate term, including possible new small to mid-scale experiments, US contributions to large experiments, upgrades to existing experiments, R&D plans and theory. The workshop was organized into (...) two sets of parallel working group sessions, divided by physics topics and technology. Physics working groups covered topics on Sterile Neutrinos, Neutrino Mixing, Neutrino Interactions, Neutrino Properties and Astrophysical Neutrinos. Technology sessions were organized into Theory, Short-Baseline Accelerator Neutrinos, Reactor Neutrinos, Detector R&D and Source, Cyclotron and Meson Decay at Rest sessions.This report summarizes discussion and conclusions from the workshop. (shrink)

Cicero's essay On Friendship (Laelius de amicitia) is of interest as much for the light it sheds on Roman society as for its embodiment of ancient philosophical views on the subjects of friendship. The Dream of Scipio was excerpted in late antiquity from Cicero's De Republica, a dialogue in six books which now only survives in fragmentary form. In the excerpt, which probably formed the conclusion to the dialogue, Cicero describes his vision of the cosmos and the rewards of immortality (...) that the good statesman can expect after death. This work is particularly important for its influence on later literature in the Middle Ages and Renaissance.Both dialogues are examples of the best Ciceronian prose. They are presented in this volume in the context of Cicero's philosophical writing. Their place in ancient thought and their literary characteristics are discussed fully in the introduction, while individual points of interpretation are dealt with in the commentary. The text of both works is new and will also be published in a forthcoming volume in the Oxford Classical Texts series. There is a separate appendix of notes on textual points. Text with translation and commentary. (Aris and Phillips 1991). (shrink)