13,485 research outputs found
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An inter-comparison of Arctic synoptic scale storms between four global reanalysis datasets
The Arctic is becoming more accessible as sea ice extent continues to decline, resulting in higher human exposure to Arctic storms. This study compares Arctic storm characteristics between the ECMWF-Interim Reanalysis, 55-year Japanese Reanalysis, NASA-Modern Era Retrospective Analysis for Research and Applications Version 2 and National Centre for Environmental Prediction-Climate Forecast System Reanalysis datasets between 1980 and 2017, in winter (DJF) and summer (JJA). It is shown that Arctic storm characteristics are sensitive to the variable used for storm tracking. Arctic storm frequency is found to be similar in summer and winter when using sea level pressure minima to track Arctic storms, whereas, the storm frequency is found to be higher in winter than summer when using 850 hPa relative vorticity to track storms, based on using the same storm tracking algorithm. It is also found that there are no significant trends in Arctic storm characteristics between 1980 and 2017. Given the sparsity of observations in the Arctic, it might be expected that there are large differences in Arctic storm characteristics between the reanalysis datasets. Though, some similar Arctic storm characteristics are found between the reanalysis datasets, it is found that the differences in Arctic storm characteristics between the reanalysis datasets are generally higher in winter than in summer. Overall, the results show that there are differences in Arctic storm characteristics between reanalysis datasets, but even larger differences can arise between using 850 hPa relative vorticity or mean sea level pressure as the storm tracking variable, which adds to the uncertainty associated with current Arctic storm characteristics
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Growing land-sea temperature contrast and the intensification of Arctic cyclones
Cyclones play an important role in the coupled dynamics of the Arctic climate system on a range of timescales. Modelling studies suggest that storminess will increase in the Arctic summer due to the enhanced land-sea thermal contrast along the Arctic coastline, in a region known as the Arctic Frontal Zone (AFZ). However, the climate models used in these studies are poor at reproducing the present-day Arctic summer cyclone climatology and so their projections of Arctic cyclones and related quantities, such as sea ice, may not be reliable. In this study we perform composite analysis of Arctic cyclone statistics using AFZ variability as an analogue for climate change. High AFZ years are characterised both by increased cyclone frequency and dynamical intensity, compared to low years. Importantly, the size of the response in this analogue suggests that GCMs may underestimate the response of Arctic cyclones to climate change, given a similar change in baroclinicity
How clinical and research failures lead to suboptimal prescribing: the example of chronic gout
Despite the existence of several effective drugs for chronic tophaceous gout, management is often neither rational nor effective. Wendy Lipworth and colleagues examine the possible reasons An evidence based or ârationalâ approach to prescribing is thought to maximise the benefit and minimise the harm from prescription drugs. Unfortunately, prescribing often does not meet this ideal despite cliniciansâ best intentions. We use treatment of chronic tophaceous gout to show how apparently irrational prescribing arises from several interacting âfailuresâ in both clinical practice and drug development
Knowledge needs and use in longâterm care homes for older people: A qualitative interview study of managersâ views
This is the final version. Available on open access from Wiley via the DOI in this record.âŻWe explore the views of managers' knowledge needs and use to optimise care practices and enhance the life experience for older people living, and staff working, in longâterm care homes (with and without nursing). This paper contributes to previous research by offering insights into the knowledge types drawn upon and used by managers to inform efforts to better support gaining and mobilising knowledge. Using a pragmatic qualitative approach, we undertook 19 semiâstructured interviews with managers and leaders in 15 care homes in the South West of England, varying in geographical location, size and type of ownership. We did a thematic analysis of the data using Framework Analysis. Our interpretations were informed by the existing literature on knowledge types. We identified three themes from our analysis as to managersâ knowledge needs and use when implementing changes. First, views about training and formal reports or âexplicit knowledgeâ consisting of the two subâthemes âgaining explicit knowledgeâ and âresearch knowledgeâ. Second, perspectives relating to practical experience or âtacit knowledgeâ and judging the use of knowledge in particular cases or âphronesisâ. Third, the role of emotion in managersâ knowledge needs and use. We found that having knowledge was positively valued by managers and leaders for improving care practices and enhancing the lives of people residing in care homes. Tacit knowledge and phronesis were particularly highly valued and we note challenges with the perceived applicability, relevance and use of research evidence. We identify that emotions are an important component within knowledge use and a need to further understand how to support the emotional wellbeing of managers so they can support care staff and residents. Greater consideration is needed as to how to optimise gaining and mobilising all knowledge types â âknowâwhat,â âknowâhow,â âknowâwhenâ and âknowâfeelâ â to benefit people living, and staff working, in care homes.National Institute for Health Research Applied Research Collaboration South West Peninsul
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Seasonal differences in the response of Arctic cyclones to climate change in CESM1
The dramatic warming of the Arctic over the last three decades has reduced both the thickness and extent of sea ice, opening opportunities for business in diverse sectors and increasing human exposure to meteorological hazards in the Arctic. It has been suggested that these changes in environmental conditions have led to an increase in extreme cyclones in the region, therefore increasing this hazard. In this study, we investigate the response of Arctic synoptic scale cyclones to climate change in a large initial value ensemble of future climate projections with the CESM1-CAM5 climate model (CESM-LE). We find that the response of Arctic cyclones in these simulations varies with season, with significant reductions in cyclone dynamic intensity across the Arctic basin in winter, but with contrasting increases in summer intensity within the region known as the Arctic Ocean cyclone maximum. There is also a significant reduction in winter cyclogenesis events within the GreenlandâIcelandâNorwegian sea region. We conclude that these differences in the response of cyclone intensity and cyclogenesis, with season, appear to be closely linked to changes in surface temperature gradients in the high latitudes, with Arctic poleward temperature gradients increasing in summer, but decreasing in winter
Elementary amenable subgroups of R. Thompson's group F
The subgroup structure of Thompson's group F is not yet fully understood. The
group F is a subgroup of the group PL(I) of orientation preserving, piecewise
linear self homeomorphisms of the unit interval and this larger group thus also
has a poorly understood subgroup structure. It is reasonable to guess that F is
the "only" subgroup of PL(I) that is not elementary amenable. In this paper, we
explore the complexity of the elementary amenable subgroups of F in an attempt
to understand the boundary between the elementary amenable subgroups and the
non-elementary amenable. We construct an example of an elementary amenable
subgroup up to class (height) omega squared, where omega is the first infinite
ordinal.Comment: 20 page
Mammalian sugar-binding receptors: known functions and unexplored roles
Mammalian glycan-binding receptors, sometimes known as lectins, interact withglycans, the oligosaccharide portions ofendogenous mammalian glycoproteins and glycolipids as well as sugars on the surfaces of microbes.Thesereceptors guide glycoproteins out of and back into cells, facilitate communication between cells through both adhesion and signaling, and allow the innate immune system to respond quickly to viral, fungal, bacterial,and parasiticpathogens.For many of the roughly one hundred glycan-binding receptors that are known in humans,there aregood descriptions of what types of glycans they bind and how selectivity for these ligands is achievedat the molecular level.In some cases, there is also comprehensive evidencefor the roles thatthe receptors playat the cellular and organismal levels. In addition to highlighting these well-understood paradigms for glycan-binding receptors, this review will suggest where gaps remain in our understandingof the physiological functions that they can serve
Universality of residence-time distributions in non-adiabatic stochastic resonance
We present mathematically rigorous expressions for the residence-time and
first-passage-time distributions of a periodically forced Brownian particle in
a bistable potential. For a broad range of forcing frequencies and amplitudes,
the distributions are close to periodically modulated exponential ones.
Remarkably, the periodic modulations are governed by universal functions,
depending on a single parameter related to the forcing period. The behaviour of
the distributions and their moments is analysed, in particular in the low- and
high-frequency limits.Comment: 8 pages, 1 figure New version includes distinction between
first-passage-time and residence-time distribution
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