4,554 research outputs found
Rhodium particles supported by thin vanadia films as model systems for catalysis: An electron microscopy study
Calyceal diverticula: a comprehensive review
Calyceal diverticula are rare outpouchings of the upper collecting system that likely have a congenital origin. Stones can be found in up to 50% of calyceal diverticula, although, over the combined reported series, 96% of patients presented with stones. Diagnosis is best made by intravenous urography or computed tomography urogram. Shock wave lithotripsy (SWL) is an option for first-line therapy in patients with stone-bearing diverticula that have radiologically patent necks in mid- to upper-pole diverticula and small stone burdens. Stone-free rates are the lowest with SWL, although patients report being asymptomatic following therapy in up to 75% of cases with extended follow-up. Ureteroscopy (URS) is best suited for management of anteriorly located mid- to upperpole diverticular stones. Drawbacks to URS include difficulty in identifying the ostium and low rate of obliteration. Percutaneous management is best used in posteriorly located mid- to lower-pole stones, and offers the ability to directly ablate the diverticulum. Percutaneous nephrolithotomy remains effective in the management of upperpole diverticula, but carries the risk of pulmonary complications unless subcostal access strategies such as triangulation or renal displacement are used. Laparoscopic surgery provides definitive management, but should be reserved for cases with large stones in anteriorly located diverticula with thin overlying parenchyma, and cases that are refractory to other treatment. This article reviews the current theories on the pathogenesis of calyceal diverticula. The current classification is examined in addition to the current diagnostic methods. Here we summarize an extensive review of the literature on the outcomes of the different treatment approaches
When Cooperation Stumbles: the effects of grades on indicators of cooperation
(English Abstract)
In western societies, grades are to date the most widespread means by which achievement and performance are assessed in educational contexts. Grades are used for their capacity to provide individuals with a clear indicator of success or failure, in particular in comparison to others; in this respect, we study their impact on particular work contexts requiring cooperation. Indeed, students are often exhorted to cooperate and work in groups, while at the same time assessed with grades and focused on inter-individual comparison. However, to the best of our knowledge, no work has investigated the effects of grades on cooperation and on indicators of cooperation, a central question to be addressed given its significance for educational trends encouraging cooperative practices, and which we propose to explore in the experimental parts of this thesis. The first experimental chapter, Chapter 4, investigates the effect of grades with regards to their capacity to highlight individual visibility and at the same time social comparison. It tries to disentangle which of these facets could affect a motivated bias likely to reduce cooperation, namely individuals' preference for information confirming their own choice. In two experiments, results showed that a graded-cooperative situation increased this preference effect in comparison to other conditions where only individual visibility was manipulated, and furthermore increased individuals' perception of a competitive atmosphere. Chapter 5 investigates the effect of grades on direct cooperative inter- individual interactions, namely on group information sharing. Two experiments showed that grades hindered informational communication between individuals, leading them to withhold crucial task-information. Finally, Chapter 6 investigates the effects of grades on another indicator of group cooperation, namely inter-individual coordination. Results indicated that showcasing grades at the onset of a cooperative task necessitating inter-individual coordination decreased group performance and elicited more negative dominant behaviours amongst participants. Together these results provide evidence that grades hamper group cooperation. We conclude by discussing implications for the practice of grading in Education.
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(Résumé en langue française)
Dans la plupart des pays occidentaux, les notes sont majoritairement utilisées pour évaluer la performance et rendre compte de la réussite scolaire des individus. Dans cette perspective, elles sont non seulement un indicateur de succès ou d'échec, mais aussi de la valeur comparative des individus. Dans cette thèse nous proposons de tester l'effet des notes lorsque celles-ci sont utilisées dans des contextes bien spécifiques de coopération. En effet, si les notes et la comparaison sociale sont pratique courante, les étudiants sont souvent encouragés et amenés à coopérer en groupe. Cependant, à notre connaissance, point d'études ont testé l'effet des notes sur la coopération; études qui seraient pourtant légitimes étant donné la tendance existante en milieu éducatif à encourager les pratiques coopératives. C'est précisément ce que proposent de faire les chapitres expérimentaux de cette thèse. Le premier (Chapitre 4) teste l'effet des notes au regard de leur capacité à accentuer à la fois la visibilité et la comparaison sociale. Deux expériences investiguent l'effet des notes et tentent de démêler ce qui, de la visibilité individuelle, de la comparaison sociale ou des deux, pourrait affecter un biais motivationnel qui réduit la propension à coopérer: la propension à préférer les informations qui confirment les choix de l'individu. Les résultats montrent qu'en situation coopérative, les notes accroissent ce biais comparativement à des situations où seule la visibilité individuelle est soulignée, suggérant de plus que les notes produisent une focalisation des individus sur une comparaison sociale compétitive. Le second (Chapitre 5) teste l'effet des notes sur les interactions coopératives des individus, précisément sur le partage d'information. Deux expériences montrent que dans un contexte de travail en groupe coopératif, les notes entravent le bon partage des informations entre individus, les amenant à faire de la rétention d'information. Enfin, le troisième (Chapitre 6) investigue l'effet des notes sur un autre indicateur de coopération en groupe: la coordination interindividuelle. Les résultats montrent que les notes réduisent la coordination des individus et les mènent à avoir des comportements de dominance négative entre eux. En somme, les notes entravent la coopération et réduisent les comportements coopératifs entre individus. Enfin, nous discutons des implications pour le milieu éducatif
Rh-V alloy formation in Rh-VOx thin films after high-temperature reduction studied by electron microscopy
Extent, duration and predictors of exclusive breastfeeding in a longitudinal study: adjusting for missing data using an accelerated failure time model and multiple imputation
Background: The World Health Organization recommends at least 6 months of exclusive breastfeeding (EBF). Longitudinal studies facilitate estimation of EBF duration, but often suffer from loss to follow-up and missing information. The study estimates the prevalence of EBF, duration and predictors of EBF duration while adjusting for missing data using multiple imputation (MI).
Methods: A longitudinal study was conducted on all women giving birth between September 2009-February 2010 in selected hospitals (N=2119). Data on EBF and socio-demographic and other characteristics were collected at birth, and at 2, 6, 12 and 24 months. Information on EBF status and duration was missing for 29%. To deal with missing data, we generated multiple datasets using logistic regression-based MI to impute missing EBF practice, and an accelerated failure time (AFT) model to impute missing duration of EBF. The latter model also identified factors associated with EBF duration.
Results: The observed 64% of women practicing EBF (95%CI; 62%-66%) was adjusted, after imputation, to 62% (95%CI; 60%-65%). After imputation, the estimated median time of EBF among women practicing EBF was 4.9 months. Predictors of EBF duration were stated intention to breastfeed, religious observance, and giving formula milk while in hospital.
Conclusion: Adjusting estimates of EBF practice and duration using MI is feasible and potentially important. Using an AFT model for EBF duration enables the execution of MI in such studies and allows direct interpretation of the impact of various factors on EBF duration. 
The Hamburg/ESO R-process Enhanced Star survey (HERES) IV. Detailed abundance analysis and age dating of the strongly r-process enhanced stars CS 29491-069 and HE 1219-0312
We report on a detailed abundance analysis of two strongly r-process
enhanced, very metal-poor stars newly discovered in the HERES project, CS
29491-069 ([Fe/H]=-2.51, [r/Fe]=+1.1) and HE 1219-0312 ([Fe/H]=-2.96,
[r/Fe]=+1.5). The analysis is based on high-quality VLT/UVES spectra and MARCS
model atmospheres. We detect lines of 15 heavy elements in the spectrum of CS
29491-069, and 18 in HE 1219-0312; in both cases including the Th II 4019 {\AA}
line. The heavy-element abundance patterns of these two stars are mostly
well-matched to scaled solar residual abundances not formed by the s-process.
We also compare the observed pattern with recent high-entropy wind (HEW)
calculations, which assume core-collapse supernovae of massive stars as the
astrophysical environment for the r-process, and find good agreement for most
lanthanides. The abundance ratios of the lighter elements strontium, yttrium,
and zirconium, which are presumably not formed by the main r-process, are
reproduced well by the model. Radioactive dating for CS 29491-069 with the
observed thorium and rare-earth element abundance pairs results in an average
age of 9.5 Gyr, when based on solar r-process residuals, and 17.6 Gyr, when
using HEW model predictions. Chronometry seems to fail in the case of HE
1219-0312, resulting in a negative age due to its high thorium abundance. HE
1219-0312 could therefore exhibit an overabundance of the heaviest elements,
which is sometimes called an "actinide boost"
The challenge of policy coordination for sustainable sociotechnical transitions: the case of the zero-carbon homes agenda in England
Emerging in recent research on sociotechnical transitions towards a low-carbon economy is the question of the extent to which such transitions require centralised, intentional coordination by government. Drawing from Hayek's conceptualisation of coordination, I evaluate the effectiveness of policy for low-carbon and zero-carbon homes in England. A detailed analysis is presented of how policy makers address complex choices and trade-offs as well as significant uncertainty. Particular attention is given to those policy decisions which are widely agreed by stakeholders to cause distortive effects. The focus here on the impacts of policy definition and delivery in terms of multiple evaluative criteria can complement and enrich the more process-orientated cross-sector and multilevel analyses that predominate in existing research on policy coordination. Furthermore, the coordination problems identified yield further insights into the actual and potential effectiveness of policy processes in shaping complex sociotechnical transitions
Measurement of UNILAC and SIS18 proton performance
On July 16th 2016 the UNILAC and SIS18 proton performance has been measured. Due to scheduled maintenance works of the UNILAC's rf-system, the post-stripper energy was restricted to 5.9~MeV and accordingly the beam quality suffered considerably from the interruption of the periodic focusing system. This limitation will not be any longer in future beam times. Six single-gap resonators were used for acceleration to 10.7~MeV. After an optimization of the multi-turn injection protons were extracted form the SIS18
The Legacy of ERA, Privatization and the Policy Ratchet
This article explores the ways in which the neo-liberal impetus toward the privatization of state schooling signalled in the Education Reform Act 1988 (ERA) has become embedded in the English school system. Four main points are made. First, that ERA itself was of huge strategic rather than substantive importance as far as privatization is concerned. Second, by tracing the lineage of privatization from ERA onwards a 'ratchet' effect of small and incremental policy moves can be identified, which have disseminated, embedded and naturalized privatization within public sector provision. Third, that while privatization has been taken up and taken much further by New Labour than it had been by the Conservatives there are differences between the two sets of governments in the role of privatization in education policy and the role of the state. Fourth, the participation of private providers in the planning and delivery of state services has put the private sector at the very heart of policy. At points the article draws upon interviews conducted with private sector providers. © 2008 Sage Publications
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