2,303 research outputs found
Evolutionary rates for multivariate traits: the role of selection and genetic variation.
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.A fundamental question in evolutionary biology is the relative importance of selection and genetic architecture in determining evolutionary rates. Adaptive evolution can be described by the multivariate breeders' equation (Δz(-)=Gβ), which predicts evolutionary change for a suite of phenotypic traits (Δz(-)) as a product of directional selection acting on them (β) and the genetic variance-covariance matrix for those traits (G ). Despite being empirically challenging to estimate, there are enough published estimates of G and β to allow for synthesis of general patterns across species. We use published estimates to test the hypotheses that there are systematic differences in the rate of evolution among trait types, and that these differences are, in part, due to genetic architecture. We find some evidence that sexually selected traits exhibit faster rates of evolution compared with life-history or morphological traits. This difference does not appear to be related to stronger selection on sexually selected traits. Using numerous proposed approaches to quantifying the shape, size and structure of G, we examine how these parameters relate to one another, and how they vary among taxonomic and trait groupings. Despite considerable variation, they do not explain the observed differences in evolutionary rates.J.H., T.T. and J.B.W. were supported by NERC, J.H. and J.B.W. by the BBSRC and J.H. by a University Royal Society Fellowship. W.P. was supported by an NERC studentship (awarded to J.H. and T.T.) and I.D. and W.P. were funded by NIH grant no. 1R01GM094424
Domestic Workload and Multiple Roles. Epidemiological findings on health and sickness absence in women
Aim: The objective of this thesis was to analyse the importance of specific exposures in women’s lives to health and sickness absence; more precisely to study the association between domestic work, multiple roles and the experience of being sick-listed, and self-rated health, psychiatric disorders and sickness absence.
Method: The thesis was based on two datasets. ‘Women’s health and living conditions’ (WHL) is a cross-sectional study on 1 417 employed women aged 17 to 64 years old. Data was collected with a questionnaire, and register and employee data on sickness absence. ‘Women and alcohol in Göteborg’ (WAG) is a prospective cohort study on 1 799 women in eight age cohorts born from 1925 to 1980. Data was collected with a screening questionnaire, interviews and register-based sickness absence. Several aspects of domestic work, multiple roles and experience of sickness absence were analysed in relation to self-rated health (SF-36), psychiatric disorders (DSM-III and IV) and sickness absence. The study on multiple roles emanated from the role strain and role enhancement hypotheses and roles were analysed as single roles and as combinations of roles. Changes in self-rated physical health were assessed in relation to experience of sickness absence over five year. Cross-sectional and longitudinal analyses were conducted using multivariate regressions analyses. Results: Domestic job strain and a lack of domestic work equity and marital satisfaction were associated with lower self-rated health particularly vitality and mental health. The former was not associated to sickness absence, but the latter was. Women with domestic workload due to children and adults with special needs had higher odds for medium-long sick-leave spells, while parental responsibility gave lower odds for any sick-leave spell. Occupation was related to lower odds for poor self-rated physical health and sickness absence, while the parental role was associated with higher odds for sickness absence. Compared with women who had all three roles women with occupation and partner role had lower odds for negative health outcomes. Support was found for the role strain hypothesis in the cross-sectional analyses of role combinations while neither of the hypotheses was supported in the five year follow up. A lower proportion of those who had experience of being sick-listed reported good health at both baseline and follow up. Women with psychiatric disorders had higher odds for a change from poor to good self-rated physical health over the five years if they had been sick-listed.
Conclusion: Domestic workload was associated to health and sickness absence in women, but there were inconsistencies in the findings on children and being a parent and on multiple roles. From a public health perspective, deeper knowledge on the importance of women’s engagement domestic work and its different dimensions is important for promoting women’s health. A multidimensional assessment of domestic work is important and the content and complexity of domestic work and of different roles needs to be further explored in relation to health and sickness absence in women
Suture Materials, 1980s: Properties, Uses, and Abuses
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66057/1/j.1365-4362.1982.tb03154.x.pd
In-operando high-speed tomography of lithium-ion batteries during thermal runaway
Prevention and mitigation of thermal runaway presents one of the greatest challenges for the safe operation of lithium-ion batteries. Here, we demonstrate for the first time the application of high-speed synchrotron X-ray computed tomography and radiography, in conjunction with thermal imaging, to track the evolution of internal structural damage and thermal behaviour during initiation and propagation of thermal runaway in lithium-ion batteries. This diagnostic approach is applied to commercial lithium-ion batteries (LG 18650 NMC cells), yielding insights into key degradation modes including gas-induced delamination, electrode layer collapse and propagation of structural degradation. It is envisaged that the use of these techniques will lead to major improvements in the design of Li-ion batteries and their safety features
Exhaled breath condensate pH as a biomarker of COPD severity in ex-smokers
Endogenous airway acidification, as assessed by exhaled breath condensate (EBC) pH, is present in patients with stable COPD. The aim of this study was to measure EBC pH levels in a large cohort of COPD patients and to evaluate associations with functional parameters according to their smoking status
GEOexplorer: a webserver for gene expression analysis and visualisation
Gene Expression Omnibus (GEO) is a database repository hosting a substantial proportion of publicly available high throughput gene expression data. Gene expression analysis is a powerful tool to gain insight into the mechanisms and processes underlying the biological and phenotypic differences between sample groups. Despite the wide availability of gene expression datasets, their access, analysis, and integration are not trivial and require specific expertise and programming proficiency. We developed the GEOexplorer webserver to allow scientists to access, integrate and analyse gene expression datasets without requiring programming proficiency. Via its user-friendly graphic interface, users can easily apply GEOexplorer to perform interactive and reproducible gene expression analysis of microarray and RNA-seq datasets, while producing a wealth of interactive visualisations to facilitate data exploration and interpretation, and generating a range of publication ready figures. The webserver allows users to search and retrieve datasets from GEO as well as to upload user-generated data and combine and harmonise two datasets to perform joint analyses. GEOexplorer, available at https://geoexplorer.rosalind.kcl.ac.uk, provides a solution for performing interactive and reproducible analyses of microarray and RNA-seq gene expression data, empowering life scientists to perform exploratory data analysis and differential gene expression analysis on-the-fly without informatics proficiency
Dissolution dominating calcification process in polar pteropods close to the point of aragonite undersaturation
Thecosome pteropods are abundant upper-ocean zooplankton that build aragonite shells. Ocean acidification results in the lowering of aragonite saturation levels in the surface layers, and several incubation studies have shown that rates of calcification in these organisms decrease as a result. This study provides a weight-specific net calcification rate function for thecosome pteropods that includes both rates of dissolution and calcification over a range of plausible future aragonite saturation states (Omega_Ar). We measured gross dissolution in the pteropod Limacina helicina antarctica in the Scotia Sea (Southern Ocean) by incubating living specimens across a range of aragonite saturation states for a maximum of 14 days. Specimens started dissolving almost immediately upon exposure to undersaturated conditions (Omega_Ar,0.8), losing 1.4% of shell mass per day. The observed rate of gross dissolution was different from that predicted by rate law kinetics of aragonite dissolution, in being higher at Var levels slightly above 1 and lower at Omega_Ar levels of between 1 and 0.8. This indicates that shell mass is affected by even transitional levels of saturation, but there is, nevertheless, some partial means of protection for shells when in undersaturated conditions. A function for gross dissolution against Var derived from the present observations was compared to a function for gross calcification derived by a different study, and showed that dissolution became the dominating process even at Omega_Ar levels close to 1, with net shell growth ceasing at an Omega_Ar of 1.03. Gross dissolution increasingly dominated net change in shell mass as saturation levels decreased below 1. As well as influencing their viability, such dissolution of pteropod shells in the surface layers will result in slower sinking velocities and decreased carbon and carbonate fluxes to the deep ocean
Are Zinc-Finger Domains of Protein Kinase C Dynamic Structures That Unfold by Lipid or Redox Activation?
Protein kinase C (PKC) is activated by lipid second messengers or redox action, raising the question whether these activation modes involve the same or alternate mechanisms. Here we show that both lipid activators and oxidation target the zinc-finger domains of PKC, suggesting a unifying activation mechanism. We found that lipid agonist-binding or redox action leads to zinc release and disassembly of zinc fingers, thus triggering large-scale unfolding that underlies conversion to the active enzyme. These results suggest that PKC zinc fingers, originally considered purely structural devices, are in fact redox-sensitive flexible hinges, whose conformation is controlled both by redox conditions and lipid agonists. Antioxid. Redox Signal. 14, 757-766.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90473/1/ars-2E2010-2E3773.pd
Offspring's leukocyte telomere length, paternal age, and telomere elongation in sperm.
PublishedJournal ArticleResearch Support, N.I.H., ExtramuralResearch Support, Non-U.S. Gov'tThis is the final version of the article. Available from Public Library of Science via the DOI in this record.Leukocyte telomere length (LTL) is a complex genetic trait. It shortens with age and is associated with a host of aging-related disorders. Recent studies have observed that offspring of older fathers have longer LTLs. We explored the relation between paternal age and offspring's LTLs in 4 different cohorts. Moreover, we examined the potential cause of the paternal age on offspring's LTL by delineating telomere parameters in sperm donors. We measured LTL by Southern blots in Caucasian men and women (n=3365), aged 18-94 years, from the Offspring of the Framingham Heart Study (Framingham Offspring), the NHLBI Family Heart Study (NHLBI-Heart), the Longitudinal Study of Aging Danish Twins (Danish Twins), and the UK Adult Twin Registry (UK Twins). Using Southern blots, Q-FISH, and flow-FISH, we also measured telomere parameters in sperm from 46 young (50 years) donors. Paternal age had an independent effect, expressed by a longer LTL in males of the Framingham Offspring and Danish Twins, males and females of the NHLBI-Heart, and females of UK Twins. For every additional year of paternal age, LTL in offspring increased at a magnitude ranging from half to more than twice of the annual attrition in LTL with age. Moreover, sperm telomere length analyses were compatible with the emergence in older men of a subset of sperm with elongated telomeres. Paternal age exerts a considerable effect on the offspring's LTL, a phenomenon which might relate to telomere elongation in sperm from older men. The implications of this effect deserve detailed study.Supported by NIH grants R01-AG021593, R01-AG020132, and P01-AG0876. Support was also provided by NIH contract NOHC25195, the NHLBI cooperative agreement grants U01 HL 67893, U01 HL67894, U01 HL67895, U01 HL67896, U01 HL67897, U01 HL67898, U01 HL67899, U01 HL67900, U01 HL67901, U01 HL67902, U01 HL56563, U01 HL56564, U01 HL56565, U01 HL56566, U01 HL56567, U01 HL56568, and U01 HL56569. Also funded in part by the Wellcome Trust grant (ref 074951)
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