1,760 research outputs found
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Grouping Individual Investment Preferences in Retirement Savings: A Cluster Analysis of a USS Members Risk Attitude Survey
Cluster analysis is used to identify homogeneous groups of members of USS in terms of risk attitudes. There are two distinct clusters of members in their 40s and 50s. One had previously ‘engaged’ with USS by making additional voluntary contributions. It typically had higher pay, longer tenure, less interest in ethical investing, lower risk capacity, a higher percentage of males, and a higher percentage of academics than members of the ‘disengaged’ cluster. Conditioning only on the attitude to risk responses, there are 18 clusters, with similar but not identical membership, depending on which clustering method is used. The differences in risk aversion across the 18 clusters could be explained largely by differences in the percentage of females and the percentage of couples. Risk aversion increases as the percentage of females in the cluster increases, while it reduces as the percentage of couples increases because of greater risk sharing within the household. Characteristics that other studies have found important determinants of risk attitudes, such as age, income and (pension) wealth, do not turn out to be as significant for USS members. Further, despite being on average more highly educated than the general population, USS members are marginally more risk averse than the general population, controlling for salary, although the difference is not significant
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One size fits all: How many default funds does a pension scheme need?
In this paper, we analyse the number of default investment funds appropriate for an occupational defined contribution pension scheme. Using a unique dataset of member risk attitudes and characteristics from a survey of a large UK pension scheme, we apply cluster analysis to identify two distinct groups of members in their 40s and 50s. Further analysis indicated that the risk attitudes of the two groups were not significantly different, allowing us to conclude that a single lifestyle default fund is appropriate
Radiocarbon Chronologies and Extinction Dynamics of the Late Quaternary Mammalian Megafauna of the Taimyr Peninsula, Russian Federation
This paper presents 75 new radiocarbon dates based on late Quaternary mammal remains recovered from eastern Taimyr Peninsula and adjacent parts of the northern Siberian lowlands, Russian Federation, including specimens of woolly mammoth (Mammuthus primigenius), steppe bison (Bison priscus), muskox (Ovibos moschatus), moose (Alces alces), reindeer (Rangifer tarandus), horse (Equus caballus) and wolf (Canis lupus). New evidence permits reanalysis of megafaunal extinction dynamics in the Asian high Arctic periphery. Increasingly, radiometric records of individual species show evidence of a gap at or near the Pleistocene/Holocene boundary (PHB). In the past, the PHB gap was regarded as significant only when actually terminal, i.e., when it marked the apparent ‘‘last’’ occurrence of a species (e.g., current ‘‘last’’ occurrence date for woolly mammoth in mainland Eurasia is 9600 yr BP). However, for high Arctic populations of horses and muskoxen the gap marks an interruption rather than extinction, because their radiocarbon records resume, nearly simultaneously, much later in the Holocene. Taphonomic effects, ΔC14 flux, and biased sampling are unlikely explanations for these hiatuses. A possible explanation is that the gap is the signature of an event, of unknown nature, that prompted the nearly simultaneous crash of many megafaunal populations in the high Arctic and possibly elsewhere in Eurasia.
A renal registry for Africa: first steps.
There is a dearth of data on end-stage renal disease (ESRD) in Africa. Several national renal registries have been established but have not been sustainable because of resource limitations. The African Association of Nephrology (AFRAN) and the African Paediatric Nephrology Association (AFPNA) recognize the importance of good registry data and plan to establish an African Renal Registry. This article reviews the elements needed for a successful renal registry and gives an overview of renal registries in developed and developing countries, with the emphasis on Africa. It then discusses the proposed African Renal Registry and the first steps towards its implementation. A registry requires a clear purpose, and agreement on inclusion and exclusion criteria, the dataset and the data dictionary. Ethical issues, data ownership and access, the dissemination of findings and funding must all be considered. Well-documented processes should guide data collection and ensure data quality. The ERA-EDTA Registry is the world's oldest renal registry. In Africa, registry data have been published mainly by North African countries, starting with Egypt and Tunisia in 1975. However, in recent years no African country has regularly reported national registry data. A shared renal registry would provide participating countries with a reliable technology platform and a common data dictionary to facilitate joint analyses and comparisons. In March 2015, AFRAN organized a registry workshop for African nephrologists and then took the decision to establish, for the first time, an African Renal Registry. In conclusion, African nephrologists have decided to establish a continental renal registry. This initiative could make a substantial impact on the practice of nephrology and the provision of services for adults and children with ESRD in many African countries
An Intact Kidney Slice Model to Investigate Vasa Recta Properties and Function in situ
Background: Medullary blood flow is via vasa recta capillaries, which possess contractile pericytes. In vitro studies using isolated descending vasa recta show that pericytes can constrict/dilate descending vasa recta when vasoactive substances are present. We describe a live kidney slice model in which pericyte-mediated vasa recta constriction/dilation can be visualized in situ. Methods: Confocal microscopy was used to image calcein, propidium iodide and Hoechst labelling in ‘live’ kidney slices, to determine tubular and vascular cell viability and morphology. DIC video-imaging of live kidney slices was employed to investigate pericyte-mediated real-time changes in vasa recta diameter. Results: Pericytes were identified on vasa recta and their morphology and density were characterized in the medulla. Pericyte-mediated changes in vasa recta diameter (10–30%) were evoked in response to bath application of vasoactive agents (norepinephrine, endothelin-1, angiotensin-II and prostaglandin E2) or by manipulating endogenous vasoactive signalling pathways (using tyramine, L-NAME, a cyclo-oxygenase (COX-1) inhibitor indomethacin, and ATP release). Conclusions: The live kidney slice model is a valid complementary technique for investigating vasa recta function in situ and the role of pericytes as regulators of vasa recta diameter. This technique may also be useful in exploring the role of tubulovascular crosstalk in regulation of medullary blood flow
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Sporormiella as a tool for detecting the presence of large herbivores in the Neotropics
The reliability of using the abundance of Sporormiella spores as a proxy for the presence and abundance of megaherbivores was tested in southern Brazil. Mud-water interface samples from nine lakes, in which cattle-use was categorized as high, medium, or low, were assayed for Sporormiella representation. The sampling design allowed an analysis of both the influence of the number of animals using the shoreline and the distance of the sampling site from the nearest shoreline. Sporormiella was found to be a reliable proxy for the presence of large livestock. The concentration and abundance of spores declined from the edge of the lake toward the center, with the strongest response being in sites with high livestock use. Consistent with prior studies in temperate regions, we find that Sporormiella spores are a useful proxy to study the extinction of Pleistocene megafauna or the arrival of European livestock in Neotropical landscapes
Microbiome profiling by Illumina sequencing of combinatorial sequence-tagged PCR products
We developed a low-cost, high-throughput microbiome profiling method that
uses combinatorial sequence tags attached to PCR primers that amplify the rRNA
V6 region. Amplified PCR products are sequenced using an Illumina paired-end
protocol to generate millions of overlapping reads. Combinatorial sequence
tagging can be used to examine hundreds of samples with far fewer primers than
is required when sequence tags are incorporated at only a single end. The
number of reads generated permitted saturating or near-saturating analysis of
samples of the vaginal microbiome. The large number of reads al- lowed an
in-depth analysis of errors, and we found that PCR-induced errors composed the
vast majority of non-organism derived species variants, an ob- servation that
has significant implications for sequence clustering of similar high-throughput
data. We show that the short reads are sufficient to assign organisms to the
genus or species level in most cases. We suggest that this method will be
useful for the deep sequencing of any short nucleotide region that is
taxonomically informative; these include the V3, V5 regions of the bac- terial
16S rRNA genes and the eukaryotic V9 region that is gaining popularity for
sampling protist diversity.Comment: 28 pages, 13 figure
Rethinking media responsibility in the refugee ‘crisis’: a visual typology of European news
In this paper, we analyse how news images of the 2015 Syrian refugee ‘crisis’ visualise refugees and how, in so doing, they mobilise various forms of moral responsibility in ‘our’ mediated public life – various practical dispositions of action towards the misfortunes of migrants and refugees at Europe’s border. On the basis of empirical material from European news (June-December 2015), we construct a typology of visibilities of the ‘crisis’, each of which situates refugees within a different regime of visibility and claim to action: i) visibility as biological life, associated with monitorial action; ii) visibility as empathy associated with charitable action; iii) visibility as threat, associated with state security; iv) visibility as hospitality, associated with political activism; and v) visibility as selfreflexivity, associated with a post-humanitarian engagement with people like ‘us’. In conclusion, we argue that, important as these five categories of visibility are in introducing public dispositions to action towards the vulnerable, they nonetheless ultimately fail to humanise migrants and refugees. This failure to portray them as human beings with lives that are worth sharing should compel us, we urge, to radically re-think how we understand the media’s responsibility towards vulnerable others
Pulcherrimin formation controls growth arrest of the Bacillus subtilis biofilm
Biofilm formation by Bacillus subtilis is a communal process that culminates in the formation of architecturally complex multicellular communities. Here we reveal that the transition of the biofilm into a nonexpanding phase constitutes a distinct step in the process of biofilm development. Using genetic analysis we show that B. subtilis strains lacking the ability to synthesize pulcherriminic acid form biofilms that sustain the expansion phase, thereby linking pulcherriminic acid to growth arrest. However, production of pulcherriminic acid is not sufficient to block expansion of the biofilm. It needs to be secreted into the extracellular environment where it chelates Fe 3+ from the growth medium in a nonenzymatic reaction. Utilizing mathematical modeling and a series of experimental methodologies we show that when the level of freely available iron in the environment drops below a critical threshold, expansion of the biofilm stops. Bioinformatics analysis allows us to identify the genes required for pulcherriminic acid synthesis in other Firmicutes but the patchwork presence both within and across closely related species suggests loss of these genes through multiple independent recombination events. The seemingly counterintuitive self-restriction of growth led us to explore if there were any benefits associated with pulcherriminic acid production. We identified that pulcherriminic acid producers can prevent invasion by neighboring communities through the generation of an “iron-free” zone, thereby addressing the paradox of pulcherriminic acid production by B. subtilis. </p
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