9,785 research outputs found
Myopia in late adolescence and subsequent multiple sclerosis among men
BACKGROUND: Risk factors such as low vitamin D level has been implicated in the etiology of multiple sclerosis (MS) and may be relevant to myopia, such that there may be an association between myopia and MS. METHODS: Using linked Swedish national register data, we conducted a cohort study of men who were born in Sweden between 1950 and 1992, lived in Sweden between 1990 and 2018, and enrolled in military conscription assessment (n = 1,847,754). Myopia was defined based on the spherical equivalent refraction measured at conscription assessment, around age 18 years. Multiple sclerosis was identified using the Patient Register. Cox regression produced hazard ratios (HR) with 95% confidence intervals (95% CI), with adjustment for demographic and childhood socioeconomic characteristics and residential region. Due to changes in the assessment of refractive error, the analysis was stratified into two groups by the year of conscription assessment: 1969-1997 and 1997-2010. RESULTS: Among 1,559,859 individuals during a maximum of 48 years of follow-up from age 20 to 68 years (44,715,603 person-years), there were 3,134 MS events, and the incidence rate 7.0 (95% CI [6.8, 7.3] per 100,000 person-years). Among individuals with conscription assessments during 1997-2010, there were 380 MS events. There was no evidence of an association between myopia and MS, with HR 1.09 (95% CI 0.83, 1.43). Among individuals who underwent conscription assessment in 1969-1997, there were 2754 MS events. After adjusting for all covariates, there was no evidence of an association between myopia and MS (HR 0.99 [95% CI 0.91, 1.09]). CONCLUSION: Myopia in late adolescence is not associated with a subsequent raised risk of MS and thus there does not appear to be important shared risk factors
Fitness benefits of prolonged post-reproductive lifespan in women
Most animals reproduce until they die, but in humans, females can survive long after ceasing reproduction. In theory, a prolonged post-reproductive lifespan will evolve when females can gain greater fitness by increasing the success of their offspring than by continuing to breed themselves. Although reproductive success is known to decline in old age, it is unknown whether women gain fitness by prolonging lifespan post-reproduction. Using complete multi-generational demographic records, we show that women with a prolonged post-reproductive lifespan have more grandchildren, and hence greater fitness, in pre-modern populations of both Finns and Canadians. This fitness benefit arises because post-reproductive mothers enhance the lifetime reproductive success of their offspring by allowing them to breed earlier, more frequently and more successfully. Finally, the fitness benefits of prolonged lifespan diminish as the reproductive output of offspring declines. This suggests that in female humans, selection for deferred ageing should wane when one's own offspring become post-reproductive and, correspondingly, we show that rates of female mortality accelerate as their offspring terminate reproduction
Motif Statistics and Spike Correlations in Neuronal Networks
Motifs are patterns of subgraphs of complex networks. We studied the impact
of such patterns of connectivity on the level of correlated, or synchronized,
spiking activity among pairs of cells in a recurrent network model of integrate
and fire neurons. For a range of network architectures, we find that the
pairwise correlation coefficients, averaged across the network, can be closely
approximated using only three statistics of network connectivity. These are the
overall network connection probability and the frequencies of two second-order
motifs: diverging motifs, in which one cell provides input to two others, and
chain motifs, in which two cells are connected via a third intermediary cell.
Specifically, the prevalence of diverging and chain motifs tends to increase
correlation. Our method is based on linear response theory, which enables us to
express spiking statistics using linear algebra, and a resumming technique,
which extrapolates from second order motifs to predict the overall effect of
coupling on network correlation. Our motif-based results seek to isolate the
effect of network architecture perturbatively from a known network state
Distribution and abundance of fish and crayfish in a Waikato stream in relation to basin area
The aim of this study was to relate the longitudinal distribution of fish and crayfish to increasing basin area and physical site characteristics in the Mangaotama Stream, Waikato region, North Island, New Zealand. Fish and crayfish were captured with two-pass removal electroshocking at 11 sites located in hill-country with pasture, native forest, and mixed land uses within the 21.6 km2 basin. Number of fish species and lineal biomass of fish increased with increasing basin area, but barriers to upstream fish migration also influenced fish distribution; only climbing and non-migratory species were present above a series of small waterfalls. Fish biomass increased in direct proportion to stream width, suggesting that fish used much of the available channel, and stream width was closely related to basin area. Conversely, the abundance of crayfish was related to the amount of edge habitat, and therefore crayfish did not increase in abundance as basin area increased. Densities of all fish species combined ranged from 17 to 459 fish 100 m-2, and biomass ranged from 14 to 206 g m-2. Eels dominated the fish assemblages, comprising 85-100% of the total biomass; longfinned eels the majority of the biomass at most sites. Despite the open access of the lower sites to introduced brown trout, native species dominated all the fish communities sampled
Foreign-language effects in cross-cultural behavioral research: Evidence from the Tanzanian Hadza
Behavioral research in traditional subsistence populations is often conducted in a non-native language. Recent studies show that non-native language-use systematically influences behavior, including in widely used methodologies. However, such studies are largely conducted in rich, industrialized societies, using at least one European language. This study expands sample diversity. We presented four standard tasksâa âdictatorâ game, two sacrificial dilemmas, a wager task, and five Likert-risk tolerance measuresâto 129 Hadza participants. We randomly varied study languagesâHadzane and Kiswahiliâbetween participants. We report a moderate impact of study language on wager decisions, alongside a substantial effect on dilemma decisions and responses to Likert-assessments of risk. As expected, non-native languages fostered utilitarian choices in sacrificial dilemmas. Unlike previous studies, non-native-language-use decreased risk preference in wager and Likert-tasks. We consider alternative explanatory mechanisms to account for this reversal, including linguistic relativity and cultural context. Given the strength of the effects reported here, we recommend, where possible, that future cross-cultural research should be conducted in participantsâ first language
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Inverse Consistency Error in the Registration of Prone and Supine Images in CT Colonography
Robust registration between prone and supine data acquisitions for CT colonography is pivotal for medical interpretation but a challenging problem. One measure when evaluating non-rigid registration algorithms over the whole of the deformation field is the inverse consistency error, which suggests improved registration quality when the inverse deformation is consistent with the forward deformation. We show that using computed landmark displacements to initialise an intensity based registration reduces the inverse consistency error when using a state-of-the-art non-rigid b-spline registration method. This method aligns prone and supine 2D images derived from CT colonography acquisitions in a cylindrical domain. Furthermore, we demonstrate that using the same initialisation also improves registration accuracy for a set of manually identified reference points in cases exhibiting local luminal collapse
Modern foraminifera, ÎŽ\u3csup\u3e13\u3c/sup\u3eC, and bulk geochemistry of central Oregon tidal marshes and their application in paleoseismology
We assessed the utility of ÎŽ13C and bulk geochemistry (total organic content and C:N) to reconstruct relative sea-level changes on the Cascadia subduction zone through comparison with an established sea-level indicator (benthic foraminifera). Four modern transects collected from three tidal environments at Siletz Bay, Oregon, USA, produced three elevation-dependent groups in both the foraminiferal and ÎŽ13C/bulk geochemistry datasets. Foraminiferal samples from the tidal flat and low marsh are identified by Miliammina fusca abundances of \u3e 45%, middle and high marsh by M. fusca abundances of \u3c 45% and the highest marsh by Trochamminita irregularis abundances \u3e 25%. The ÎŽ13C values from the groups defined with ÎŽ13C/bulk geochemistry analyses decrease with an increasing elevation; â 24.1 ± 1.7â° in the tidal flat and low marsh; â 27.3 ± 1.4â° in the middle and high marsh; and â 29.6 ± 0.8â° in the highest marsh samples. We applied the modern foraminiferal and ÎŽ13C distributions to a core that contained a stratigraphic contact marking the great Cascadia earthquake of AD 1700. Both techniques gave similar values for coseismic subsidence across the contact (0.88 ± 0.39 m and 0.71 ± 0.56 m) suggesting that ÎŽ13C has potential for identifying amounts of relative sea-level change due to tectonics
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Analyzing food value chains for nutrition goals
First proposed in 2010, the use of âvalue chain analysisâ to identify opportunities for targeted nutrition interventions in food systems is still an emerging method. This review explores and summarizes the application of value chain analysis to nutrition and from this provides five insights into how to more effectively conduct value chain analysis for nutrition: 1) use a consumer perspective to inform selection of foods and chains; 2) consider the research question, available resources, and the type of chain; 3) situate consumer research at the center of the analysis; 4) assess economic trade-offs; and 5) pay attention to governance and stakeholdersâ capacity for and incentives to change
School tuck shops in South Africaâan ethical appraisal
It can be postulated that schools have an ethical responsibility to protect children from an unhealthy food environment. Against
the backdrop of stunting, overweight and micronutrient deficiencies prevalent in South African children, the aim of this scoping
study is to review information available on foods sold to school children within an ethical framework. While some schools have
a formal tuck shop, at other schools, food vendors sell food either on or outside the school premises. Ten studies, of which two
were national, fit the selection criteria for this study. Available data show that mostly unhealthy food options are sold to South
African school children; with low-nutrient energy-dense foods (e.g. chips, sweets) and sugar sweetened beverages being the
most popular. The Integrated School Health Policy provide a policy framework for achieving healthy school food environments in
South Africa, and several guidelines are available in South African to assist school tuck shops to sell healthier options. Childrenâs
preference for unhealthy foods, the cost of healthier food options and a lack of proper facilities may however be barriers for
implementing healthy tuck shops. An action stronger than merely providing guidelines may therefore be needed. Cognisance
needs to be taken of conflicting value based arguments within ethical perspectives. Given these conflicts, the authors argue that
an Ethics of Responsibility contributes to the debate of the best and supports the notion that society at large has a responsibility
to protect vulnerable communities of which school children are part. Presently an ethical vacuum exists in terms of rights and
responsibilities which this study hopes to address.DHE
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