Tremor of the extended third digit and bipolar surface and needle electromyograms of the extensor digitorum were recorded from six healthy volunteers for the purpose of elucidating the motor-unit activity responsible for the 8- to 12-Hz component of physiological finger tremor. Tremor was measured with a force transducer during steady voluntary contractions of approximately 200-250 g. The surface EMGs were full-wave rectified and low-pass filtered (-3 dB at 21 Hz), producing the envelope of the surface EMG (the demodulated EMG). Spectral analyses of simultaneous tremor and demodulated EMG records were performed. In four of six subjects, a pronounced 8- to 12-Hz amplitude modulation in the surface EMG was present, and coherency analysis demonstrated that this modulation was strongly correlated with the well-known 8- to 12-Hz tremor. In two subjects this amplitude modulation and tremor were barely detectable, despite the sensitive recording and analysis techniques used in this study. Spectral analysis was performed on 43 motor-unit spike trains. Twenty-two spike trains, having mean firing frequencies in the range of 10-22 spikes/s, produced statistically significant spectral peaks at 8-12 Hz, in addition to the expected spectral peaks at the mean firing frequencies. Of the 22 8- to 12-Hz-producing motor units, 12 had mean firing frequencies in the range of 17-22 spikes/s and exhibited the greatest 8- to 12-Hz activities of all motor units recorded. These motor units displayed transient sequences of double discharges in which interspike intervals (ISIS) of approximately 8-30 ms alternated with ISIS of 60-90 ms, thus producing an 8- to 12-Hz spectral peak. Adjacent ISIS of these motor units were correlated in the range of -0.5 to -0.9. Coherency analyses demonstrated that the 8- to 12-Hz activities of these motor units were correlated with the 8- to 12-Hz finger tremor and surface EMG modulation. The remaining 10 8- to 12-Hz-producing motor units had mean firing frequencies in the range of 10-17 spike/s. Although these motor units did not display the intense double-discharge firing pattern of the more rapidly firing motor units, a tendency toward action potential grouping was present and resulted in 8- to 12-Hz spectral activities which were correlated with the tremor and surface EMG modulation. .. ..

Our impressions of Canadian resource‐dependent communities are often still influenced by the classic works of Innis, Robinson, Lucas, Siemens, and others. Although this research has proven to be valuable, it has also established several generalizations regarding these settings, including the perceptions that community labour forces and economic structures are relatively homogenous, that nonresource sectors play an insignificant role in the communities, and that these communities are found primarily in isolated northern regions. These generalizations are now beginning to be questioned, given the rapid economic and social changes taking place in these communities and the recent theoretical and empirical contributions of geographers and other social scientists. This paper summarizes this classic research, then challenges these generalizations by discussing recent applications of the concepts of economic restructuring and labour‐market segmentation theory to the context of resource‐dependent communities. To further illustrate these characteristics, the paper then presents an empirical analysis of 220 Canadian resource‐dependent communities across six resource sectors, focusing specifically on their labour‐market characteristics and the relationship between resource dependence and spatial isolation.Nos impressions des communautés mono‐industrielles canadiennes spécialisées dans la production des ressources sont souvent encore influencées, entre autres, par les études classiques de Innis, Robinson, Lucas, et Siemens. Bien que cette recherche ait prouvé sa valeur, elle a aussi servi àétablir plusieurs généralisations concernant ces milieux, incluant les notions que la main d'oeuvre et les structures économiques de ces communautés sont relativement homogènes, que les secteurs non‐reliés à l'exploration des ressources n'y jouent qu'un rôle peu significatif, et que ces communautés se retrouventsurtout dans les régions isolées du nord. Ces généralisations sont maintenant soumises à une remise en question, compte tenu des changements économiques et sociaux rapides dont ces communautés font l'objet et des récentes contributions théoriques et empiriques de géographes et d'autres chercheurs en sciences sociales. Cet article résume cette recherche classique et conteste ces généralisations en commentant les récentes applications du concept de restructuration économique etde la théorie de la segmentation du marché d'emploi associés au contexte des communautés dépendentes de l'extraction de ressources. Afin d'illustrer ces caractéristiques, l'article présente une analyse empirique portant sur 220 communautés canadiennes et sur six secteurs de ressources, etse concentre plus spécifiquement sur les caractéristiques de leur marché de la main‐d'oeuvre et sur les liens existant entre la condition de dépendance à une ressource et l'isolation spatiale.

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Community is a key construct in population health research and a major locus of health determinants study. In recent years in Canada, a new emphasis on such research has emerged in the form of community-university partnerships, supported by several of the major research granting agencies. The authors regard such partnerships as a special case of participatory action research (PAR), albeit one where greater emphasis is placed on the institutional nature of the university research partner. Drawing from the first three years' experience of a local quality of life study, and the extant North American literature on community-university partnerships, this article explores how such partnerships are established and sustained. These processes are illustrated with critical reflections on some of the methods, actions and relational issues that arose during the authors' quality of life project. The article concludes with a brief reflection on the potential benefits and costs of the growing Canadian trend to require such partnerships as a condition for research grants.