110 resultados para Importance échantillonnale
Resumo:
The proportion of adults over the age of 60 years is expanding rapidly across European Union countries, including the Republic of Ireland. As the older population has grown faster than the total population, the proportion of older persons relative to the rest of the population has increased considerably (Figure 1). This trend mirrors the arrival of the “baby boomer� generation into early old age and will have wide ranging effects on social, political and economic spheres as well as presenting significant challenges for healthcare delivery and public healthcare policy.
Resumo:
Gas fired generation currently plays an integral support role ensuring security of supply in power systems with high wind power penetrations due to its technical and economic attributes. However, the increase in variable wind power has affected the gas generation output profile and is pushing the boundaries of the design and operating envelope of gas infrastructure. This paper investigates the mutual dependence and interaction between electricity generation and gas systems through the first comprehensive joined-up, multi-vector energy system analysis for Ireland. Key findings reveal the high vulnerability of the Irish power system to outages on the Irish gas system. It has been shown that the economic operation of the power system can be severely impacted by gas infrastructure outages, resulting in an average system marginal price of up to €167/MWh from €67/MWh in the base case. It has also been shown that gas infrastructure outages pose problems for the location of power system reserve provision, with a 150% increase in provision across a power system transmission bottleneck. Wind forecast error was shown to be a significant cause for concern, resulting in large swings in gas demand requiring key gas infrastructure to operate at close to 100% capacity. These findings are thought to increase in prominence as the installation of wind capacity increases towards 2020, placing further stress on both power and gas systems to maintain security of supply.
Resumo:
In this Letter, an unambiguous synthetic strategy is reported for the preparation of enantiomerically purecis-5-halo-piperazic acid derivatives in single diastereoisomer form. Contrary to the recent report by Shin and co-workers (Chem. Lett. 2001, 1172), in which it is claimed that the Ph3P and N-chlorosuccinimide (NCS)-mediated chlorination of (3R,5S)-trans-N(1),N(2)-di-t-Boc-5-hydroxy-piperazic acid derivative 1proceeds with retention of configuration at C(5) to give 2, we now show that this and related Ph3P-mediated halogenations all occur with SN2 inversion at the alcohol center, as is customary for such reactions. Specifically, we demonstrate that the (3R,5S)-trans-5-Cl-piperazic acid derivative 2 claimed by Shin and co-workers (Chem. Lett. 2001, 1172) is in actual fact the chlorinated (3S,5R)-enantiomer 6, which must have been prepared from the cis-(3S,5S)-alcohol 3, a molecule whose synthesis is not formally described in the Shin paper. We further show here that the cis-(3R,5R)-5-Cl-Piz 13 claimed by Shin and co-workers inChem. Lett. 2001, 1172, is also (3S,5R)-trans-5-Cl-Piz 6. Authentic 13 has now been synthesized by us, for the very first time, here. Since Lindsley and Kennedy have recently utilized the now invalid Shin and co-workers’ retentive Ph3P/NCS chlorination procedure on 1 in their synthetic approach to piperazimycin A (Tetrahedron Lett. 2010, 51, 2493), it follows that their claimed 5-Cl-Piz-containing dipeptide 25 probably has the alternate structure 26, where the 5-Cl-Piz residue has a 3,5-cis-configuration. The aforementioned stereochemical misassignments appear to have come from a mix-up of starting materials by Shin and co-workers (Chem. Lett. 2001, 1172), and an under-appreciation of the various steric and conformational effects that operate in N(2)-acylated piperazic acid systems, most especially rotameric A1,3-strain. The latter has now been unambiguously delineated and defined here under the banner of the A1,3-rotamer effect.
Resumo:
Behavioural phenotype research is of benefit to a large number of children with genetic syndromes and associated developmental delay. This article presents an overview of this research area and demonstrates how understanding pathways between gene disorders and behaviour can inform our understanding of the difficulties individuals with genetic syndromes and developmental delay experience, including self-injurious behaviour, social exploitation, social anxiety, social skills deficits, sensory differences, temper outbursts and repetitive behaviours. In addition, physical health difficulties and their interaction with behaviour are considered. The article demonstrates the complexity involved in assessing a child with a rare genetic syndrome.
Resumo:
In recent years, sonification of movement has emerged as a viable method for the provision of feedback in motor learning. Despite some experimental validation of its utility, controlled trials to test the usefulness of sonification in a motor learning context are still rare. As such, there are no accepted conventions for dealing with its implementation. This article addresses the question of how continuous movement information should be best presented as sound to be fed back to the learner. It is proposed that to establish effective approaches to using sonification in this context, consideration must be given to the processes that underlie motor learning, in particular the nature of the perceptual information available to the learner for performing the task at hand. Although sonification has much potential in movement performance enhancement, this potential is largely unrealised as of yet, in part due to the lack of a clear framework for sonification mapping: the relationship between movement and sound. By grounding mapping decisions in a firmer understanding of how perceptual information guides learning, and an embodied cognition stance in general, it is hoped that greater advances in use of sonification to enhance motor learning can be achieved.
Resumo:
A recent experimental investigation (Kim et al. J. Catal. 306 (2013) 146-154) on the selective hydrogenation of acetylene over Pd nanoparticles with different shapes concluded that Pd(100) showed higher activity and selectivity than Pd(111) for acetylene hydrogenation. However, our recent density functional calculations (Yang et al. J. Catal. 305 (2013) 264-276) observed that the clean Pd(111) surface should result in higher activity and ethylene selectivity compared with the clean Pd(100) surface for acetylene hydrogenation. In the current work, using density functional theory calculations, we find that Pd(100) in the carbide form gives rise to higher activity and selectivity than Pd(111) carbide. These results indicate that the catalyst surface is most likely in the carbide form under the experimental reaction conditions. Furthermore, the adsorption energies of hydrogen atoms as a function of the hydrogen coverage at the surface and subsurface sites over Pd(100) are compared with those over Pd(111), and it is found that the adsorption of hydrogen atoms is always less favoured on Pd(100) over the whole coverage range. This suggests that the Pd(100) hydride surface will be less stable than the Pd(111) hydride surface, which is also in accordance with the experimental results reported.
Resumo:
Purpose
The study contributes to the literature on public value and performance examining politicians’ and managers’ perspectives by investigating the importance they attach to the different facets of performance information (i.e. budgetary, accrual based- and non-financial information (NFI)).
Design/methodology/approach
We survey politicians and managers in all Italian municipalities of at least 80,000 inhabitants.
Findings
Overall, NFI is more appreciated than financial information (FI). Moreover, budgetary accounting is preferred to accrual accounting. Politicians’ and managers’ preferences are generally aligned.
Research limitations/implications
NFI as a measure of public value is not alternative, but rather complementary, to FI. The latter remains a fundamental element of public sector accounting due to its role in resource allocation and control.
Practical implications
The preference for NFI over FI and of budgetary over accruals accounting suggests that the current predominant emphasis on (accrual-based) financial reporting might be misplaced.
Originality/value
Public value and performance are multi-faceted concepts. They can be captured by different types of information and evaluated according to different criteria, which will also depend on the category of stakeholders or users who assesses public performance. So far, most literature has considered the financial and non-financial facets of performance as virtually separate. Similarly, in the practice, financial management tends to be decoupled from non-financial performance management. However, this research shows that only by considering their joint interactions we can achieve an accurate representation of what public value really is.
Resumo:
The prenatal period is of critical importance in defining how individuals respond to their environment throughout life. Stress experienced by pregnant females has been shown to have detrimental effects on offspring behaviour, health and productivity. The sheep has been used extensively as a model species to inform human studies. However, in the farmed environment, the consequences for the lamb of the imposition of prenatal stresses upon the ewe have received much less attention. The stressors that pregnant ewes are most frequently exposed to include sub-optimal nutrition and those related to housing, husbandry and environment which may be either acute or chronic. A systematic review of the literature was adopted to identify material which had production-relevant maternal stressors and lamb outcomes. The current review focussed upon the lamb up to weaning around the age of 100 days and the results clearly demonstrate that stressors imposed upon the ewe have implications for offspring welfare and performance. Maternal under-nutrition (UN) in the last third of pregnancy consistently impaired lamb birth-weight and subsequent vigour and performance, while earlier UN had a variable effect on performance. Feeding the ewe above requirements did not have positive effects on lamb performance and welfare. Social and husbandry stressors such as transport, shearing, mixing and physiological treatments designed to mimic acute stress which would be considered disadvantageous for the ewe had positive or neutral effects for the lamb, highlighting a potential conflict between the welfare of the ewe and her lamb. This review also identified considerable gaps in knowledge, particularly in respect of the impact of disease upon the ewe during pregnancy and interactions between different stressors and the responses of ewe and lamb.
Resumo:
The prenatal period is of critical importance in defining how individuals respond to their environment throughout life. Stress experienced by pregnant females has been shown to have detrimental effects on offspring biology in humans and a variety of other species. It also is becoming increasingly apparent that prenatal events can have important consequences for the behavior, health, and productivity of offspring in farmed species. Pregnant cattle may experience many potentially important stressors, for instance, relating to their social environment, housing system and physical environment, interactions with humans and husbandry procedures, and their state of health. We examined the available literature to provide a review of the implications of prenatal stress for offspring welfare in cattle. The long-term effects of dystocia on cattle offspring also are reviewed. To ensure a transparent and repeatable selection process, a systematic review approach was adopted. The research literature clearly demonstrates that prenatal stress and difficult births in beef and dairy cattle both have implications for offspring welfare and performance. Common husbandry practices, such as transport, were shown to influence offspring biology and the importance of environmental variables, including thermal stress and drought, also were highlighted. Maternal disease during pregnancy was shown to negatively impact offspring welfare. Moreover, dystocia-affected calves suffer increased mortality and morbidity, decreased transfer of passive immunity, and important physiological and behavioral changes. This review also identified considerable gaps in our knowledge and understanding of the effects of prenatal stress in cattle. © 2012 American Society of Animal Science. All rights reserved.
Resumo:
There is no consensus in the literature as to which stock characteristic best explains returns. In this study, we employ a novel econometric approach better suited than the traditional characteristic sorting method to answer this question for the UK market. We evaluate the relative explanatory power of market, size, momentum, volatility, liquidity and book-to-market factors in a semiparametric characteristic-based factor model which does not require constructing characteristic portfolios. We find that momentum is the most important factor and liquidity is the least important based on their relative contribution to the fit of the model and the proportion of sample months for which factor returns are significant. Overall, this study provides strong evidence to support that the momentum characteristic can best explain stock returns in the UK market. The econometric approach employed in this study is a novel way to assess relevant investment risk in international financial markets outside U.S. Moreover, multinational institutions and investors can use this approach to identify regional factors in order to diversify their portfolios.