189 research outputs found
Double-resonant fast particle-wave interaction
In future fusion devices fast particles must be well confined in order to
transfer their energy to the background plasma. Magnetohydrodynamic
instabilities like Toroidal Alfv\'en Eigenmodes or core-localized modes such as
Beta Induced Alfv\'en Eigenmodes and Reversed Shear Alfv\'en Eigenmodes, both
driven by fast particles, can lead to significant losses. This is observed in
many ASDEX Upgrade discharges. The present study applies the drift-kinetic
HAGIS code with the aim of understanding the underlying resonance mechanisms,
especially in the presence of multiple modes with different frequencies. Of
particular interest is the resonant interaction of particles simultaneously
with two different modes, referred to as 'double-resonance'. Various mode
overlapping scenarios with different q profiles are considered. It is found
that, depending on the radial mode distance, double-resonance is able to
enhance growth rates as well as mode amplitudes significantly. Surprisingly, no
radial mode overlap is necessary for this effect. Quite the contrary is found:
small radial mode distances can lead to strong nonlinear mode stabilization of
a linearly dominant mode.Comment: 12 pages, 11 figures; Nuclear Fusion 52 (2012
Computer programs for saturation properties of hydrogen
Computer programs for saturation properties of liquid and vapor hydroge
Aménagement en courbes de niveau et conservation du carbone
Dans la région Mali-sud, au climat semi-aride, la culture sur billons suivant les courbes de niveau permet d'arrêter l'érosion et surtout d'augmenter l'infiltration de l'eau de pluie, ce qui permet l'augmentation de la croissance des plantes cultivées et des arbres associés aux cultures. Il en résulte des effets sur l'ensemble du cycle du carbone. Les teneurs en carbone du sol sableux ferrugineux tropicaux diminuent rapidement sous culture, jusqu'à environ 0,2 à 0,4% dans l'horizon superficiel (0-20 cm). Pendant le même temps, les rendements peuvent rester stables ou augmenter si les modestes apports d'engrais sont suffisants pour corriger les carences en phosphore et fournir un peu de N et K aux cultures. Les rendements moyens, par exemple 10 à 20 q/ha de maïs, sont comparables à ceux qui étaient obtenus en Europe au début du 20ème siècle, quand l'utilisation des engrais a commencé. L'érosion contribue à diminuer encore plus les teneurs en carbone, dans certaines parties de la toposéquence. L'arrêt de l'érosion permet d'éviter ces pertes. Par contre, la production de biomasse par les cultures est augmentée: environ 50% pour le mil, le sorgho et le maïs pendant les années peu pluvieuses. Le carbone est recyclé dans le milieu suivant les voies habituelles: l'alimentation humaine (grains), l'alimentation des animaux (résidus, pailles, adventices), les termites, le fumier, les usages domestiques, le feu. Le parc arboré (karité et autres espèces) profite de l'eau conservée grâce aux courbes de niveau et il s'accroît par la croissance des arbres en place et par la régénération de jeunes arbres. Il en résulte d'une part, un accroissement de la masse ligneuse et d'autre part une augmentation des teneurs en carbone du sol dans les parties du champ couvertes par ces arbres (apports organiques et ombrage). Les courbes de niveau sont marquées par des ados couverts d'une végétation permanente (#Andropogon gayanus#, etc.) qui couvrent 2 à 4% de la surface des champs, avec des teneurs en carbone du sol comparables à celles qu'on trouve sous végétation naturelle. L'effet de l'aménagement sur le stockage du carbone se manifeste donc dans différentes situations (les cultures, des ados enherbés, les arbres, le sol sous les arbres, etc.) et suivant des cycles variables (l'année pour les cultures et les feuilles des arbres, quelques années pour le carbone du sol, quelques dizaines d'années pour le bois). (Résumé d'auteur
Coffee and tomato share common gene repertoires as revealed by deep sequencing of seed and cherry transcripts
An EST database has been generated for coffee based on sequences from approximately 47,000 cDNA clones derived from five different stages/tissues, with a special focus on developing seeds. When computationally assembled, these sequences correspond to 13,175 unigenes, which were analyzed with respect to functional annotation, expression profile and evolution. Compared with Arabidopsis, the coffee unigenes encode a higher proportion of proteins related to protein modification/turnover and metabolism—an observation that may explain the high diversity of metabolites found in coffee and related species. Several gene families were found to be either expanded or unique to coffee when compared with Arabidopsis. A high proportion of these families encode proteins assigned to functions related to disease resistance. Such families may have expanded and evolved rapidly under the intense pathogen pressure experienced by a tropical, perennial species like coffee. Finally, the coffee gene repertoire was compared with that of Arabidopsis and Solanaceous species (e.g. tomato). Unlike Arabidopsis, tomato has a nearly perfect gene-for-gene match with coffee. These results are consistent with the facts that coffee and tomato have a similar genome size, chromosome karyotype (tomato, n=12; coffee n=11) and chromosome architecture. Moreover, both belong to the Asterid I clade of dicot plant families. Thus, the biology of coffee (family Rubiacaeae) and tomato (family Solanaceae) may be united into one common network of shared discoveries, resources and information
Network analysis of the Viking Age in Ireland as portrayed in Cogadh Gaedhel re Gallaibh
Cogadh Gaedhel re Gallaibh (‘The War of the Gaedhil with the Gaill’) is a medieval Irish text, telling how an army under the leadership of Brian Boru challenged Viking invaders and their allies in Ireland, culminating with the Battle of Clontarf in 1014. Brian’s victory is widely remembered for breaking Viking power in Ireland, although much modern scholarship disputes traditional perceptions. Instead of an international conflict between Irish and Viking, interpretations based on revisionist scholarship consider it a domestic feud or civil war. Counterrevisionists challenge this view and a long-standing and lively debate continues. Here, we introduce quantitative measures to the discussions.We present statistical analyses of network data embedded in the text to position its sets of interactions on a spectrum from the domestic to the international. This delivers a picture that lies between antipodal traditional and revisionist extremes; hostilities recorded in the text are mostly between Irish and Viking—but internal conflict forms a significant proportion of the negative interactions too
The organic geochemistry of ancient sediments, part II
Chemical analysis of sediment and oil hydrocarbon content by gas chromatography and mass spectrometry to establish inception period of bio-organic evolutio
A real-time, quantitative PCR method using hydrolysis probes for the monitoring of Plasmodium falciparum load in experimentally infected human volunteers
Background: The accurate quantification of Plasmodium falciparum parasite numbers by PCR is an important tool for monitoring growth kinetics in subjects infected and subsequently treated with anti-malarial agents
Impact of pharmaceutical promotion on prescribing decisions of general practitioners in Eastern Turkey
<p>Abstract</p> <p>Background</p> <p>Commercial sources of information are known to have greater influence than scientific sources on general practitioners' (GPs) prescribing behavior in under developed and developing countries. The study aimed to determine the self-reported impact of pharmaceutical promotion on the decision-making process of prescription of GPs in Eastern Turkey.</p> <p>Methods</p> <p>A cross-sectional, exploratory survey was performed among 152 GPs working in the primary health centers and hospitals in Erzurum province of Eastern Turkey in 2006. A self-administered structured questionnaire was used. The questionnaire included questions regarding sociodemographics, number of patients per day, time per patient, frequency of sales representative visits to GPs, participation of GPs in training courses on prescribing (in-service training, drug companies), factors affecting prescribing decision, reference sources concerning prescribing and self-reported and self-rated effect of the activities of sales representatives on GPs prescribing decisions.</p> <p>Results</p> <p>Of 152 subjects, 53.3% were male and 65.8% were working at primary health care centers, respectively. Mean patient per day was 58.3 ± 28.8 patients per GP. For majority of the GPs (73.7%), the most frequent resource used in case of any problems in prescribing process was drug guides of pharmaceutical companies. According to self-report of the GPs, their prescribing decisions were affected by participation in any training activity of drug companies, frequent visits by sales representatives, high number of patient examinations per day and low year of practice (p < 0.05 for all).</p> <p>Conclusion</p> <p>The results of this study suggest that for the majority of the GPs, primary reference sources concerning prescribing was commercial information provided by sales representatives of pharmaceutical companies, which were reported to be highly influential on their decision-making process of prescribing by GPs. Since this study was based on self-report, the influence reported by the GPs may have been underestimated.</p
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Laying the foundations for implementing Magnet principles in hospitals in Europe: A qualitative analysis
Background: Magnet hospitals, a concept developed in the U.S., have been associated with improved nurse recruitment and retention, and better patient outcomes. Magnet principles may be useful to address workforce challenges in European hospitals, but they have not been implemented or evaluated on a large scale in the European hospital context.
Objective: This study aims to explore the initial phase of implementing Magnet principles in 11 acute care hospitals in six European countries. The specific objectives of the study were to investigate the type of work that characterises the early phase of implementation and how implementation leaders engage with their context.
Methods: A multinational qualitative study was conducted, with data from 23 semi-structured, one-to-one interviews with implementation leaders in 11 acute care hospitals in six European countries. Thematic analyses guided the analysis of data.
Findings: Three themes of core work processes during the early phase of implementing Magnet principles in European hospitals were identified. The first theme, ‘Creating space for Magnet’, describes how work was directed towards creating both political and organisational space for the project. The second theme, ‘Framing to fit: understanding and interpreting Magnet principles’, describes the translational work to understand what the Magnet model entails and how it relates to the local hospital context. Finally, the third theme, ‘Calibrating speed and dose’, describes the strategic work of considering internal and external factors to adjust the process of implementation.
Conclusions: The first phase of implementation was characterised by conceptual and relational work; translating the Magnet concepts, considering the fit into existing structures and practices and making space for Magnet in the local context. Understanding the local context played an important role in shaping and guiding the navigation of professional and organisational tensions. Hospitals employed diverse strategies to either emphasise or downplay the role of nurses and nursing to facilitate progress in the implementation
Acute non-ambulatory tetraparesis with absence of the dens in two large breed dogs: case reports with a radiographic study of relatives
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