TPV Foaming by CO2 Extrusion: Processing and Modelling.

This work focuses on the extrusion foaming under CO2 of commercial TPV and how the process influences the final morphology of the foam. Moreover, numerical modelling of the cell growth of the extrusion foaming is developed. The results show how a precise control on the saturation pressure, die geometry, temperature and nucleation can provide a homogeneous foam having a low density (<500 kg/m3). This work demonstrates that an optimum of CO2 content must be determined to control the coalescence phenomenon that appears for high levels of CO2. This is explained by longer residence times in the die (time of growth under confinement) and an early nucleation (expansion on the die destabilizes the polymer flow). Finally, this work proposes a model to predict the influence of CO2 on the flow (plasticizing effect) and a global model to simulate the extrusion process and foaming inside and outside the die. For well-chosen nucleation parameters, the model predicts the final mean radius of the cell foam as well as final foam density.

Private Health Insurance in France: Between Europeanization and Collectivization.

Policy Points Private health insurance (PHI) in France has been facing critical changes over the past 30 years. A complementary and voluntary scheme, it has been historically dominated by nonprofit entities. However, the share of for-profit insurance companies in the sector has significantly increased. Nonprofit firms also changed their strategies and mimicked some for-profit behaviors. The present paper argues that this process is a result of the conflict-provoking coevolution of the insurance and health care sectors. Trying to improve the regulation of the insurance industry as whole, two European directives first jeopardized the business model of nonprofit entities. Then, two national reforms designed to improve health coverage significantly increased competition among insurers, notably in the area of corporate-level contracts. Decoupling the insurance and health care sectors has become a major source of policy feedback and unexpected outcomes of reforms affecting the very organization of PHI. CONTEXT: In France, private health insurance (PHI) has an exceptionally high level of coverage and accounts for 13.7% of health expenditures. A complementary and voluntary scheme, it has been historically dominated by nonprofit, mutual benefit societies. Over the past 20 years, however, the market share of for-profit insurance companies has increased by 47%. Financialization of the field developed, and competition based on new risk management strategies also increased. The broad aim of this paper is to characterize and to elucidate the causes of this trend. More specifically, we are interested in how and to what extent a series of supranational and national policies contributed to this situation. METHOD: Our data come from three sources. We first reviewed documents published by health insurers, government reports, and newspaper articles. We then conducted two semistructured interview campaigns between September 2017 and May 2018. The first mostly covered private and public actors and their involvement in European Union (EU) policymaking (n = 21). The second series of interviews was conducted with another group of actors directly involved at the French level (n = 16). FINDINGS: Our findings support preliminary observations. PHI in France, we argue, is indeed facing a development of competition and marketlike instruments. Four major policies (two EU directives and two national reforms) played a significant role in this outcome. Surprisingly, however, it has never been the purpose of legislators and policymakers: while EU directives created a regulatory framework for insurance activities within the Single Market, policies adopted at the national level initially aimed at improving health coverage. We show that it is the interactions and the noncoordination among all of these policies that explain their unexpected outcome. CONCLUSIONS: The trend described in this paper is twofold. The first is Europeanization, as PHI in France is increasingly affected by EU legislation. Since this framework tends to favor larger firms and for-profit companies, a reduction in statutory coverage can no longer be considered a quasi-neutral transfer from (publicly owned) social security to nonprofit providers. At the same time, PHI is shifting toward collectivization: as competition increases, complementary health coverage is becoming gradually standardized and based at the corporate level. Together, these changes are likely to reduce freedom of choice and individual welfare, an assumption supported by studies published on the most recent period.

The influence of target distance on perceptual self-motion thresholds and the vestibulo-ocular reflex during interaural translation.

An elegant and influential mathematical model of eye movements is the geometric compensation required for visual fixation location in the translational vestibulo-ocular reflex (VOR). Compensatory eye velocity scales with the inverse of fixation distance during head translation because larger angular eye movements are required to minimize retinal slip during head translation when targets are closer. This model has been extensively verified in experiments. Since the VOR and vestibular perception have shared anatomic pathways, we asked whether the same scaling may affect motion perception. Since perception does not require the linear-to-angular transformation required for the translational VOR, we hypothesized that perception would not scale with target distance. Subjects were tested with a motion direction-recognition threshold task in which they reported their perception of small translations of their body. Thresholds were measured in three conditions: (1) with a near target (0.20m) that extinguished just before each motion; (2) with a far target (0.47m); 3) with no target. The subject was always in darkness during motion. Thresholds were 0.59, 0.61 and 0.61cm/s, respectively. Translational VOR sensitivity (eye angular velocity divided by head translation velocity) was also measured and modulated with target distance. The scaling ratio of responses for the near vs. far target was 0.97 for perceptual thresholds, which was significantly different from the compensatory ratio (2.35; P<0.001) and the translational VOR scaling ratio (1.59; P=0.007) but not from no compensation (1.00; P=0.93). Thus, we conclude that despite shared anatomy for the VOR and perception, the brain processes signals according to the geometric functional constraints of each task.

HEALTH TECHNOLOGY ASSESSMENT: THE SCIENTIFIC CAREER OF A POLICY CONCEPT.

OBJECTIVES: The aim of this work was to provide a comprehensive overview of the evolution of the health technology assessment (HTA) concept in the scientific literature through a scientometric approach. METHODS: A literature search was conducted, by selecting publications, as well as news from the media, containing "health technology assessment" in their title, abstracts, or keywords. We then undertook a bibliometric and network analysis on the corpus of 2,865 publications thus obtained. RESULTS: Since a first publication in 1978, interest in HTA remained marginal until a turning point in the late 1980s, when growth of the number of publications took off alongside the creation of the U.K.'s NICE agency. Since then, publications have spread across several journals. The ranking of the organizations that publish such articles does not reflect any hegemonic position. However, HTA-related scientific production is strongly concentrated in Commonwealth and Nordic countries. Despite its transnational aspects, research on HTA has been framed within a small number of scientific networks and by a few opinion leaders. CONCLUSIONS: The "career" of the HTA concept may be seen as a scientific-knowledge based institutionalization of a public policy. To succeed in a country, HTA first needs scientific prerequisites, such as an organized scientific community working on the health sector and health services. Then, it appears that the recognition of this research by decision makers plays a key role in the development of the field.