177 research outputs found
Non-simplicial quantum toric varieties
In this paper, we define quantum toric varieties associated to an arbitrary
fan in a finitely generated subgroup of some generalizing the
article arXiv:2002.03876 of Katzarkov, Lupercio, Meersseman and Verjovsky.Comment: 25 pages, 1 figur
Simulation of a supersonic hydrogen-air autoignition-stabilized flame using reduced chemistry
A three-step mechanism for H2-air combustion (Boivin et al., Proc. Comb. Inst. 33, 2010) was recently designed to reproduce both autoignition and flame propagation, essential in lifted flame stabilization. To study the implications of the use of this reduced chemistry in the context of a turbulent flame simulation, this mechanism has been implemented in a compressible explicit code and applied to the simulation of a supersonic lifted co-flowing hydrogen-air flame. Results are compared with experimental measurements (Cheng et al. C&F 1994) and simulations using detailed chemistry, showing that the reduced chemistry is very accurate. A new explicit diagnostic to readily identify autoignition regions in the post-processing of a turbulent hydrogen flame simulation is also proposed, based on variables introduced in the development of the reduced chemical mechanism.This work was supported by the UE Marie Curie ITN MYPLANET, by the Spanish MCINN through projects # ENE2008-06515 and # CSD2010-00010 and by the Comunidad de Madrid through project # S2009/ENE-1597. We acknowledge fruitful discussions on hydrogen chemistrywith Prof. A.L. S´anchez and Prof. F.A. Williams. We also wish to thank Prof. T. S. Cheng and Prof. R. W. Pitz for providing experimental data in electronic form.European Community's Seventh Framework ProgramPublicad
From Craft to Reflective Art and Science Comment on “Metrics and Evaluation Tools for Patient Engagement in Healthcare Organization- and System-Level Decision-Making: A Systematic Review”
Abstract
Patient engagement practices are increasingly incorporated in health research, governance, and care. More
recently, a large number of evaluation tools and metrics have been developed to support engagement evaluation.
This growing interest in evaluation reflects a maturation of the patient engagement field, moving from a “craft”
to a reflective “art and science,” with more explicit expected benefits and risks, better understood conditions
for success and failure, and increasingly rigorous evaluation instruments to improve engagement theories and
interventions. It also supports a more critical view of engagement science, moving beyond reductionist views of
engagement as a “black box technology” to a more subtle view of this broad category of complex interventions.
Structured evaluation can advance patient engagement by supporting more reflective partnerships between
patients, clinicians, health system leaders and citizens. This can help clarify mutual (and potentially
contradictory) expectations toward engagement, provide a reality check toward claims of benefits and harms,
and increase health systems’ capacity to implement effective engagement practices over time. To do so, closer
collaborations are required between engagement scientists and practitioners to align the theories, practice and
evaluation of patient and community engagement
Spatio-temporal requirements for transposable element piRNA-mediated silencing during Drosophila oogenesis
International audienceDuring Drosophila oogenesis, transposable element (TE) repression involves the Piwi-interacting RNA (piRNA) pathway which ensures genome integrity for the next generation. We developed a transgenic model to study repression of the Idefix retrotrans-poson in the germline. Using a candidate gene KD-approach, we identified differences in the spatio-temporal requirements of the piRNA pathway components for piRNA-mediated silencing. Some of them (Aub, Vasa, Spn-E) are necessary in very early stages of oogenesis within the germarium and appear to be less important for efficient TE silencing thereafter. Others (Piwi, Ago3, Mael) are required at all stages of oogenesis. Moreover, during early oogenesis, in the dividing cysts within the germarium, Idefix anti-sense transgenes escape host control, and this is associated with very low piwi expression. Silencing of P-element-based transgenes is also strongly weakened in these cysts. This region, termed the 'Piwiless pocket' or Pilp, may ensure that new TE insertions occur and are transmitted to the next generation, thereby contributing to genome dynamics. In contrast, piRNA-mediated silencing is strong in germline stem cells in which TE mobilization is tightly repressed ensuring the continued production of viable germline cysts
What Health System Challenges Should Responsible Innovation in Health Address? Insights From an International Scoping Review
Abstract
Background: While responsible innovation in health (RIH) suggests that health innovations could be purposefully
designed to better support health systems, little is known about the system-level challenges that it should address. The
goal of this paper is thus to document what is known about health systems’ demand for innovations.
Methods: We searched 8 databases to perform a scoping review of the scientific literature on health system challenges
published between January 2000 and April 2016. The challenges reported in the articles were classified using the
dynamic health system framework. The countries where the studies had been conducted were grouped using the human
development index (HDI). Frequency distributions and qualitative content analysis were performed.
Results: Up to 1391 challenges were extracted from 254 articles examining health systems in 99 countries. Across
countries, the most frequently reported challenges pertained to: service delivery (25%), human resources (23%), and
leadership and governance (21%). Our analyses indicate that innovations tend to increase challenges associated to human
resources by affecting the nature and scope of their tasks, skills and responsibilities, to exacerbate service delivery issues
when they are meant to be used by highly skilled providers and call for accountable governance of their dissemination,
use and reimbursement. In countries with a low and medium HDI, problems arising with infrastructure, logistics and
equipment were described in connection with challenges affecting procurement, supply and distribution systems. In
countries with a medium and high HDI, challenges included a growing demand for drugs and new technology and the
management of rising costs. Across all HDI groups, the need for flexible information technologies (IT) solutions to reach
rural areas was underscored.
Conclusion: Highlighting challenges that are common across countries, this study suggests that RIH should aim to
reduce the cost of innovation production processes and attend not only to the requirements of the immediate clinical
context of use, but also to the vulnerabilities of the broader system wherein innovations are deployed. Policy-makers
should translate system-level demand signals into innovation development opportunities since it is imperative to foster
innovations that contribute to the success and sustainability of health systems
Host-specific competitiveness to form nodules in Rhizobium leguminosarum symbiovar viciae
Fabeae legumes such as pea and faba bean form symbiotic nodules with a large diversity of soil Rhizobium leguminosarum symbiovar viciae (Rlv) bacteria. However, bacteria competitive to form root nodules (CFN) are generally not the most efficient to fix dinitrogen, resulting in a decrease in legume crop yields. Here, we investigate differential selection by host plants on the diversity of Rlv. A large collection of Rlv was collected by nodule trapping with pea and faba bean from soils at five European sites. Representative genomes were sequenced. In parallel, diversity and abundance of Rlv were estimated directly in these soils using metabarcoding. The CFN of isolates was measured with both legume hosts. Pea/faba bean CFN were associated to Rlv genomic regions. Variations of bacterial pea and/or faba bean CFN explained the differential abundance of Rlv genotypes in pea and faba bean nodules. No evidence was found for genetic association between CFN and variations in the core genome, but variations in specific regions of the nod locus, as well as in other plasmid loci, were associated with differences in CFN. These findings shed light on the genetic control of CFN in Rlv and emphasise the importance of host plants in controlling Rhizobium diversity
Strontium ranelate and alendronate have differing effects on distal tibia bone microstructure in women with osteoporosis
The structural basis of the antifracture efficacy of strontium ranelate and alendronate is incompletely understood. We compared the effects of strontium ranelate and alendronate on distal tibia microstructure over 2 years using HR-pQCT. In this pre-planned, interim, intention-to-treat analysis at 12 months, 88 osteoporotic postmenopausal women (mean age 63.7 ± 7.4) were randomized to strontium ranelate 2 g/day or alendronate 70 mg/week in a double-placebo design. Primary endpoints were changes in microstructure. Secondary endpoints included lumbar and hip areal bone mineral density (aBMD), and bone turnover markers. This trial is registered with http://www.controlled-trials.com, number ISRCTN82719233. Baseline characteristics of the two groups were similar. Treatment with strontium ranelate was associated with increases in mean cortical thickness (CTh, 5.3%), cortical area (4.9%) and trabecular density (2.1%) (all P < 0.001, except cortical area P = 0.013). No significant changes were observed with alendronate. Between-group differences in favor of strontium ranelate were observed for CTh, cortical area, BV/TV and trabecular density (P = 0.045, 0.041, 0.048 and 0.035, respectively). aBMD increased to a similar extent with strontium ranelate and alendronate at the spine (5.7% versus 5.1%, respectively) and total hip (3.3% versus 2.2%, respectively). No significant changes were observed in remodeling markers with strontium ranelate, while suppression was observed with alendronate. Within the methodological constraints of HR-pQCT through its possible sensitivity to X-ray attenuation of different minerals, strontium ranelate had greater effects than alendronate on distal tibia cortical thickness and trabecular volumetric density
Rapport de sondages et d'analyses, Le Kilian et les carrières anciennes de trachyte dans la Chaîne des Puys (Puy-de-Dôme)
En 2008, l'existence de carrières souterraines médiévales avait été mise en évidence dans la pente ouest du Bois de Manson qui domine la dépression du Cratère Kilian, au pied sud du puy de Dôme. En 2009-2010, des sondages et prospections ont été étendus à tout l'ensemble du Kilian de façon à préciser l'étendue et, si possible, la chronologie de son exploitation dans le passé. Ces travaux ont permis d'observer, dans le fond du cratère et sur son flanc interne ouest, des amoncellements de déblais d'un volume considérable, témoignant d'une extraction de roche à grande échelle durant le haut Moyen Âge et très probablement aussi à l'époque gallo-romaine. Une nouvelle carrière souterraine a été découverte dans la pente interne ouest du cratère. La base du remplissage de cette carrière a livré des charbons datés entre la fin du IV e siècle et le début du VI e siècle par le radiocarbone, tandis que le sommet du remplissage contenait des tessons de céramique datables, par leur typologie, de la fin du V e siècle au début du VIII e siècle. L'état actuel des investigations conduit à faire l'hypothèse que les gallo-romains ont exploité, au fond du cratère, un trachyte compact dont on ne trouve aujourd'hui que les déchets de taille, et dont les affleurements sont masqués par les déblais, tandis que les artisans du Moyen Âge ont recherché un trachyte plus tendre dans les pentes hautes du cratère. Le Kilian doit donc s'ajouter aux trois sources actuellement connues de trachyte d'oeuvre dans le passé, à savoir les volcans Sarcoui, Aumône (ou petit Suchet) et Cliersou. Dès cette découverte, en 2008, s'est posée la question de savoir quelle part éventuelle le trachyte du Kilian avait pu prendre dans la construction du temple de Mercure au sommet du puy de Dôme et dans l'agglomération gallo-romaine située au col de Ceyssat. Pour y répondre, une campagne d'analyses géochimiques et pétrographiques été engagée pour caractériser, aux fins de comparaison, non seulement les trachytes du Kilian et ceux des ruines gallo-romaines, mais, de plus, les trachytes du Cliersou, de l'Aumône et du Sarcoui. Ces analyses ont finalement montré qu'il est possible de faire une discrimination statistiquement significative entre les différents trachytes étudiés, à l'exception de ceux du couple Cliersou-Aumône dont les laves sont très peu différentes les unes des autres. Le résultat le plus remarquable est que tous les trachytes gallo-romains échantillonnés (dont 10 échantillons distincts au temple de Mercure et 10 au col de Ceyssat) se rattachent sans ambiguïté au Kilian. En toute rigueur, ces nouvelles données ne permettent pas d'exclure sans appel la possibilité d'utilisation à l'époque gallo-romaine, au temple de Mercure et au col de Ceyssat, de trachytes provenant d'autres sources que le Kilian (cas des chaperons de mur du col de Ceyssat, provenant du puy de Dôme). Cependant, il faut ajouter qu'un examen visuel des trachytes d'oeuvre dans ces deux sites, portant sur un nombre de moellons et d'éléments architecturaux bien supérieur au nombre de ceux qui ont été analysés, conduit à conclure que leur source est probablement commune. Cette conclusion est basée sur un faciès minéralogique particulier, observable à l'oeil nu ou à la loupe
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