What is a crystal?

Almost 25 years have passed since Shechtman discovered quasicrystals, and 15 years since the Commission on Aperiodic Crystals of the International Union of Crystallography put forth a provisional definition of the term crystal to mean ``any solid having an essentially discrete diffraction diagram.'' Have we learned enough about crystallinity in the last 25 years, or do we need more time to explore additional physical systems? There is much confusion and contradiction in the literature in using the term crystal. Are we ready now to propose a permanent definition for crystal to be used by all? I argue that time has come to put a sense of order in all the confusion.Comment: Submitted to Zeitschrift fuer Kristallographi

Crosscutting, what is and what is not? A Formal definition based on a Crosscutting Pattern

Crosscutting is usually described in terms of scattering and tangling. However, the distinction between these concepts is vague, which could lead to ambiguous statements. Sometimes, precise definitions are required, e.g. for the formal identification of crosscutting concerns. We propose a conceptual framework for formalizing these concepts based on a crosscutting pattern that shows the mapping between elements at two levels, e.g. concerns and representations of concerns. The definitions of the concepts are formalized in terms of linear algebra, and visualized with matrices and matrix operations. In this way, crosscutting can be clearly distinguished from scattering and tangling. Using linear algebra, we demonstrate that our definition generalizes other definitions of crosscutting as described by Masuhara & Kiczales [21] and Tonella and Ceccato [28]. The framework can be applied across several refinement levels assuring traceability of crosscutting concerns. Usability of the framework is illustrated by means of applying it to several areas such as change impact analysis, identification of crosscutting at early phases of software development and in the area of model driven software development

Describing return to work after stroke : a feasibility trial of 12-month outcomes

Objective: Stroke is the greatest cause of disability in adults. A quarter of strokes in the UK affect people of working age, yet under half of them return to work after stroke. There has been little investigation into what constitutes “return to work” following stroke. The aim of this study is to describe the work metrics of stroke survivor participants in a feasibility randomized controlled trial of an early stroke specific vocational rehabilitation intervention. Methods: Retrospective analysis of trial data. Metrics on work status, working hours, workplace accommodations and costs were extracted from trial out - comes gathered by postal questionnaire at 3, 6, and 12 months’ post-randomization for 46 stroke participants in a feasibility randomized controlled trial. Participants were randomized to receive vocational rehabilitation (intervention) or usual care (control). Results: Two-thirds ( n = 29; 63%) of participants re - turned to work at some point in the 12 months following stroke. Participants took a mean of 90 days to return to work. Most returned to the same role with an existing employer. Only one-third of participants who were employed full-time at stroke onset were working full-time at 12 months post-stroke. Most participants experienced a reduction in pre-stroke earnings. Workplace accommodations were more common among intervention group participants. More intervention participants than control participants reported satisfaction with work at both 6 and 12 months post-randomization. Conclusion: This study illustrates the heterogeneous nature of return to work and the dramatic impact of stroke on work status, working hours and income. Longitudinal research should explore the socioeconomic legacy of stroke and include clear definitions of work and accurate measures of working hours and income from all sources

Just What IS a Watershed?

OVERVIEW: The student will observe the elements of a local watershed and begin to develop an appreciation for the need to protect watersheds as valuable resources. The student will observe the interdependence of a variety of factors on a watershed. These factors include local geology, the ecology of the watershed, and the effect of man’s influence.Environmental Science Institut

What is the temperature of a granular medium?

In this paper we discuss whether thermodynamical concepts and in particular the notion of temperature could be relevant for the dynamics of granular systems. We briefly review how a temperature-like quantity can be defined and measured in granular media in very different regimes, namely the glassy-like, the liquid-like and the granular gas. The common denominator will be given by the Fluctuation-Dissipation Theorem, whose validity is explored by means of both numerical and experimental techniques. It turns out that, although a definition of a temperature is possible in all cases, its interpretation is far from being obvious. We discuss the possible perspectives both from the theoretical and, more importantly, from the experimental point of view

What is a Fair Reponse to Juvenile Crime?

The question of how to deal fairly and effectively with the problem of juvenile crime has long perplexed the public and policy makers. The current juvenile justice system in New York State reflects this uncertainty -- as it simultaneously employs two completely different models for the adjudication of juveniles accused of unlawful acts. The first model emphasizes the provision of rehabilitative services for delinquent youth through noncriminal proceedings in the Family Court. The second model stresses the use of punitive sanctions in the adult criminal courts for more serious juvenile offenders. To begin to sort through these models, this Essay first examines the development of the current juvenile justice system in New York State. It then examines the assumptions and values underlying these two models. This Essay then contends that increased prosecution of juveniles would by unlikely to improve the current situation. The Essay then concludes by noting factors that have limited the fairness and effectiveness of the Family Court\u27s rehabilitative model

What is a definition for in school mathematics?

This paper discusses the place of definitions in school mathematics, considering official UK curriculum guidance, literature related to definitions in advanced mathematical thinking and to experimental teaching focused on student development of definitions. A two dimensional framework is suggested for considering their functions, the ways in which students are expected to relate to them and their didactic purposes. Two contrasting examples of definitions from textbooks are analysed using systemic-functional linguistic tools