Measurement of atomic diffraction phases induced by material gratings

Atom-surface interactions can significantly modify the intensity and phase of atom de Broglie waves diffracted by a silicon nitride grating. This affects the operation of a material grating as a coherent beam splitter. The phase shift induced by diffraction is measured by comparing the relative phases of serveral interfering paths in a Mach-Zehnder Na atom interferometer formed by three material gratings. The values of the diffraction phases are consistent with a simple model which includes a van der Waals atom-surface interaction between the Na atoms and the silicon nitride grating bars.Comment: 4 pages, 5 figures, submitted to PR

Power conversion architecture for grid interface at high switching frequency

This paper presents a new power conversion architecture for single-phase grid interface. The proposed architecture is suitable for realizing miniaturized ac-dc converters operating at high frequencies (HF, above 3 MHz) and high power factor, without the need for electrolytic capacitors. It comprises of a line-frequency rectifier, a stack of capacitors, a set of regulating converters, and a power combining converter (or set of power combining converters). The regulating converters have inputs connected to capacitors on the capacitor stack, and provide regulated outputs while also achieving high power factor, with twice-line-frequency energy buffered on the capacitor stack. The power combining converter combines power from the individual regulated outputs to a single output, and may also provide isolation. While this architecture can be utilized with a variety of circuit topologies, it is especially suited for systems operating at HF (above 3 MHz), and we introduce circuit implementations that enable efficient operation in this range. The proposed approach is demonstrated for an LED driver operating from 120 V[subscript ac], and supplying a 35 V, 30 W output. The prototype converter operates at a (variable) switching frequency of 5-10 MHz and an efficiency of > 93%. The converter achieves a displacement power density of 130 W/in[superscript 3], while providing a 0.89 power factor, without the use of electrolytic capacitors

Design Methodology for a Very High Frequency Resonant Boost Converter

This paper introduces a design methodology for a resonant boost converter topology that is suitable for operation at very high frequencies. The topology we examine features a low parts count and fast transient response, but suffers from higher device stresses compared to other topologies that use a larger number of passive components. A numerical design procedure is developed for this topology that does not rely on time-domain simulation sweeps across parameters. This allows the optimal converter design to be found for a particular main semiconductor switch. If an integrated power process is used where the designer has control over layout of the semiconductor switch, the optimal combination of converter design and semiconductor layout can be found. To validate the proposed converter topology and design approach, a 75-MHz prototype converter is designed and experimentally demonstrated. The performance of the prototype closely matches that predicted by the design procedure, and the converter achieves good efficiency over a wide input voltage range

Le syntagme intonatif en langage spontané : étude préliminaire

Une étude portant sur le syntagme intonatif (SI) en langage spontané menée à partir d’un corpus de français du Québec révèle des valeurs relativement stables quant à la longueur de ces SI exprimée en termes d’unités prosodiques minimales. La variabilité rencontrée ne peut être exprimée à l’aide de paramètres sociaux.A study of intonational phrasing (IP) in a corpus of spontaneous speech of Quebec French reveals relatively stable values of length of IPs when expressed in terms of minimal prosodic units. Variability in IP length is not statistically related to the social characteristics of the speakers

Two-Stage Power Conversion Architecture Suitable for Wide Range Input Voltage

This paper presents a merged-two-stage circuit topology suitable for either wide-range dc input voltage or ac line voltage at low-to-moderate power levels (e.g., up to 30 W). This two-stage topology is based on a soft-charged switched-capacitor preregulator/transformation stage and a high-frequency magnetic regulator stage. Soft charging of the switched capacitor circuit, zero voltage switching of the high-frequency regulator circuit, and time-based indirect current control are used to maintain high efficiency, high power density, and high power factor. The proposed architecture is applied to an LED driver circuit, and two implementations are demonstrated: a wide input voltage range dc-dc converter and a line interfaced ac-dc converter. The dc-dc converter shows 88%-96% efficiency at 30-W power across 25-200-V input voltage range, and the ac-dc converter achieves 88% efficiency with 0.93 power factor at 8.4-W average power. Contributions of this paper include: 1) demonstrating the value of a merged two-stage architecture to provide substantial design benefits in high-input voltage, low-power step down conversion applications, including both wide-range-input dc-dc and line-input ac-dc systems; 2) introduction of a multimode soft-charged SC stage for the merged architecture that enables compression of an 8:1 input voltage range into a 2:1 intermediate range, along with its implementation, loss considerations, and driving methods; and 3) merging of this topology with an resonant transition discontinuous-mode inverted buck stage and pseudocurrent control to enable step-down power conversion (e.g., for LED lighting) operating at greatly increased frequencies and reduced magnetics size than with more conventional approaches

La décroissance de la population du Québec : Si on peut la prévoir, peut-on la prévenir?

La fécondité du Québec est la plus faible parmi toutes les provinces canadiennes, et selon toute vraisemblance la population du Québec s’achemine vers la décroissance. Dans cet article, les auteurs tentent d’expliciter certains des scénarios possibles qui pourraient empêcher cette décroissance. Dans un premier temps, ils présentent brièvement les tendances actuelles et précisent les hypothèses retenues pour la simulation. Puis, ils examinent les résultats en situant la décroissance dans le temps et en définissant l’ordre de grandeur de la population maximale. Et finalement, ils présentent certains des scénarios de rechange qui pourraient empêcher la décroissance.Quebec's fertility is the lowest in Canada, and it is most likely that its population is heading for a decline. In this paper, the authors try to make explicit some of the scenarios which could prevent this decline. They first briefly present the current trends and specify the assumptions used in the simulation. Then, they analyse the results by investigating the onset of the decline and the maximum size of the population. And finally, they present some of the replacement scenarios which may prevent the decline.La fecundidad del Québec es la más baja entre todas las provincias canadienses y evidentemente va hacía un decrecimiento. En este artículo, los autores tratan de explicar algunos escenarios posibles para imperdirlo. Presentan brevemente en primer lugar las tendencias actuales e indican las hipótesis retenidos para la simulación. Examinan luego los resultados ubicando el decrecimiento en el tiempo y definiendo la magnitud de la despoblación máxima. Finalmente, presentan algunos escenarios de recambio que podrían impedir dicho decrecimiento

Factors influencing interprofessional practices of physiotherapists working in private settings with people with low back pain: a qualitative study

Purpose: Collaboration and interprofessional practices are highly valued in health systems everywhere, partly based on the rationale that they improve outcomes of care for people with complex health problems, such as low back pain. Research in the area of low back pain also supports the involvement of different health professionals in the interventions for people who present this condition. The aim of this studywas to identify factors influencing the interprofessional practices of physiotherapists working in private settings with people with low back pain. Relevance: Physiotherapists, like other health professionals, are encouraged to engage in interprofessional practices in their dailywork. However, to date, very little is known of their interprofessional practices, especially in private settings. Understanding physiotherapists' interprofessional practices and their influencing factors will notably advance knowledge relating to the organisation of physiotherapy services for people with low back pain. Participants: Participants in this study were 13 physiotherapists including 10 women and 3 men, having between 3 and 22 years of professional experience, and working in one of 10 regions of the Province of Quebec (Canada). In order to obtain maximal variation in the perspectives, participants were selected using a recruitment matrix including three criteria: duration of professional experience, work location, and physical proximity with other professionals. Methods: Thiswas a descriptive qualitative study using faceto- face semi-structured interviews as the main method of data collection. An interview guide was developed based on an evidence-derived frame of reference. Each interview lasted between 55 and 95 minutes and was transcribed verbatim. Analysis: Qualitative analyses took the form of content analysis, encompassing data coding and general thematic regrouping. NVivo version 8 was used to assist data organisation and analysis. Results: Multiple factors influencing the interprofessional practices of physiotherapists were identified. The main factors include the consulting person's health condition, the extent of knowledge on health professionals' roles and fields of practice, the proximity and availability of professional resources, as well as daily work schedules. Conclusions: Our findings highlight the influence of multiple factors on physiotherapists' interprofessional practices, including professional practice and organisational issues. However, further research on the interprofessional practices of physiotherapists is still required. Research priorities targeting the views of other health professionals, as well as those of services users, would enhance our comprehension of interprofessional practices of physiotherapists. Implications: This study provides new insights that improve our understanding of the interprofessional practices of physiotherapists working in private settings with people with low back pain, more specifically on the factors influencing these practices. Based on our findings, implementing changes such as improving current and future health professionals' knowledge of the fields and roles of other health professionals through training may contribute to positively influencing interprofessional practices. Keywords: Interprofessional practices; Private practice; Low back pain Funding acknowledgements: This research was supported in part by a B.E. Schnurr Memorial Fund Research Grant administered by the Physiotherapy Foundation of Canada, as well as from a clinical research partnership in physiotherapy between the Quebec Rehabilitation Research Network (REPAR) and the Ordre professionnel de la physiothérapie du Québec (OPPQ). KP received doctoral-level scholarships from the Canadian Institutes of Health Research (CIHR) and the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST). CE Dionne is a FRSQ senior Research Scholar. Ethics approval: This project was approved by the ethics research committee of the Institut de réadaptation en déficience physique de Québec