Special Quasirandom Structures: a selection approach for stochastic homogenization

We adapt and study a variance reduction approach for the homogenization of elliptic equations in divergence form. The approach, borrowed from atomistic simulations and solid-state science [von Pezold et al, Physical Review B 2010; Wei et al, Physical Review B 1990; Zunger et al, Physical Review Letters 1990], consists in selecting random realizations that best satisfy some statistical properties (such as the volume fraction of each phase in a composite material) usually only obtained asymptotically. We study the approach theoretically in some simplified settings (one-dimensional setting, perturbative setting in higher dimensions), and numerically demonstrate its efficiency in more general cases

Analysis of the Workforce and Workplace for Rheumatology, and the Research Activities of Rheumatologists Early in Their Careers

[Excerpt] The scope and scale of clinical research is unknown for any medical or surgical specialty beyond snapshots of the broad aims and expenditures of research programs sponsored by federal agencies or the pharmaceutical industry. As a consequence, the workforce and workplace for clinical investigation is enigmatic and unexamined even after explicit warnings that an essential arm for advancing clinical practice has been disabled. The present study was designed to assess the workforce and workplace for rheumatology, and the extent and type of research prevailing among rheumatologists early in their careers. Our findings provide fresh insights about the workforce and the workplace for rheumatology, and justify interventions to address gaps in both the scope and scale of clinical research in arthritis and rheumatism

The Scope and Scale of Clinical Research Accomplished by Rheumatologists Early in Their Careers

[Excerpt] The scope and scale of clinical research is unknown for any medical or surgical specialty beyond snap shots of the broad aims and expenditures of research programs sponsored by federal agencies or the pharmaceutical industry. As a consequence, the workforce and workplace for clinical investigation is enigmatic and unexamined even after explicit warnings that an essential arm for advancing clinical practice is disabled. The present study was designed to examine the nature and extent of investigative activity prevailing among rheumatologists early in their careers. This assessment provides a lens on: i) the fraction of early career rheumatologists who engage in investigative rheumatology, ii) the scope and scale of research in musculoskeletal diseases, iii) funding available for investigative work, iv) the impact of research-intensive institutions, and NIH-K-series awards on research, and v) the demographic backgrounds of early career rheumatologists. The results provide important new insights about the early career workforce for discovery and innovation in rheumatology. The findings integrate demographic, normative, and predictive data to provide the first estimate of the scope and scale of clinical investigation within rheumatology. The results also justify interventions for promoting investigative work, and ultimately advancing the clinical practice of rheumatology

Heat transfer from a wall cooled by a liquidspray

Ph.D.J. E. Sunderlan

Synthesis and characterisation of biologically compatible TiO2 nanoparticles

Peer reviewedPublisher PD

Design for validation: An approach to systems validation

Every complex system built is validated in some manner. Computer validation begins with review of the system design. As systems became too complicated for one person to review, validation began to rely on the application of adhoc methods by many individuals. As the cost of the changes mounted and the expense of failure increased, more organized procedures became essential. Attempts at devising and carrying out those procedures showed that validation is indeed a difficult technical problem. The successful transformation of the validation process into a systematic series of formally sound, integrated steps is necessary if the liability inherent in the future digita-system-based avionic and space systems is to be minimized. A suggested framework and timetable for the transformtion are presented. Basic working definitions of two pivotal ideas (validation and system life-cyle) are provided and show how the two concepts interact. Many examples are given of past and present validation activities by NASA and others. A conceptual framework is presented for the validation process. Finally, important areas are listed for ongoing development of the validation process at NASA Langley Research Center

The Equivalence Principle as a Stepping Stone from Special to General Relativity: A Socratic Dialog

In this paper we show how the student can be led to an understanding of the connection between special relativity and general relativity by considering the time dilation effect of clocks placed on the surface of the Earth. This paper is written as a Socratic dialog between a lecturer Sam and a student Kim.Comment: 8 pages, 1 figure, uses the revtex4 documentclass. Submitted to the American Journal of Physics. Minor modification and corrections following referees' comment

L’évolution spatiale de l’emploi dans la région métropolitaine de Montréal, 1981-1996

Un des principaux thèmes de la littérature urbaine contemporaine porte sur la répartition intramétropolitaine des activités économiques. Dans les métropoles nord-américaines, la phase la plus récente de la décentralisation de l'emploi a donné lieu aux « centre-villes périphériques » ou «  edge cities  » qui sont souvent en compétition directe avec le centre-ville traditionnel. Dans un premier temps, cette recherche examine l'ampleur de la décentralisation de l'emploi entre 1981 et 1996 dans la région métropolitaine de Montréal. Dans un deuxième temps, nous analysons la nature de la décentralisation observée : la reconcentration de l'emploi dans un nombre restreint de pôles d'emploi (polycentricité) ou une dispersion généralisée («  scatteration  »). Notre analyse utilise des données portant sur le nombre d'emplois selon le lieu d'emploi des secteurs de recensement. Nos résultats indiquent que, bien que la décentralisation existe à Montréal, elle est de nature polycentrique plutôt que dispersée, même si la dispersion généralisée semble caractériser plusieurs métropoles américaines.A major theme in contemporary urban literature concerns the intrametropolitan distribution of economic activities. In North American metropolitan areas, the most recent phase of post-WWII employment decentralisation has culminated in the creation of « suburban downtowns » or « edge cities » that are often direct competitors to the CBD. In this paper, we first examine the extent to which Montréal has undergone a decentralisation of employment over the period 1981-1996, then attempt to determine whether the observed decentralisation involves a reconcentration in a limited number of employment poles (polycentricity) or a more generalised dispersion (scatteration). Our analysis is based upon place-of-work employment data at the census tract level. The results indicate that decentralisation is indeed a reality in Montréal, and that it tends to be of a polycentric nature, rather than the more widely dispersed form that appears to be characterizing many U.S. metropolitan areas