5,760 research outputs found

    Automatic Dimension Selection for a Non-negative Factorization Approach to Clustering Multiple Random Graphs

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    We consider a problem of grouping multiple graphs into several clusters using singular value thesholding and non-negative factorization. We derive a model selection information criterion to estimate the number of clusters. We demonstrate our approach using "Swimmer data set" as well as simulated data set, and compare its performance with two standard clustering algorithms.Comment: This paper has been withdrawn by the author due to a newer version with overlapping content

    Finite-sample system identification: An overview and a new correlation method

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    Finite-sample system identification algorithms can be used to build guaranteed confidence regions for unknown model parameters under mild statistical assumptions. It has been shown that in many circumstances these rigorously built regions are comparable in size and shape to those that could be built by resorting to the asymptotic theory. The latter sets are, however, not guaranteed for finite samples and can sometimes lead to misleading results. The general principles behind finite-sample methods make them virtually applicable to a large variety of even nonlinear systems. While these principles are simple enough, a rigorous treatment of the attendant technical issues makes the corresponding theory complex and not easy to access. This is believed to be one of the reasons why these methods have not yet received widespread acceptance by the identification community and this letter is meant to provide an easy access point to finite-sample system identification by presenting the fundamental ideas underlying these methods in a simplified manner. We then review three (classes of) methods that have been proposed so far-1) Leave-out Sign-dominant Correlation Regions (LSCR); 2) Sign-Perturbed Sums (SPS); 3) Perturbed Dataset Methods (PDMs). By identifying some difficulties inherent in these methods, we also propose in this letter a new sign-perturbation method based on correlation which overcome some of these difficulties

    The quality of different types of child care at 10 and 18 months. A comparison between types and factors related to quality.

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    The quality of care offered in four different types of non-parental child care to 307 infants at 10 months old and 331 infants at 18 months old was compared and factors associated with higher quality were identified. Observed quality was lowest in nurseries at each age point, except that at 18 months they offered more learning activities. There were few differences in the observed quality of care by child-minders, grandparents and nannies, although grandparents had somewhat lower safety and health scores and offered children fewer activities. Cost was largely unrelated to quality of care except in child-minding, where higher cost was associated with higher quality. Observed ratios of children to adults had a significant impact on quality of nursery care; the more infants or toddlers each adult had to care for, the lower the quality of the care she gave them. Mothers' overall satisfaction with their child's care was positively associated with its quality for home-based care but not for nursery settings

    Understanding Shoot and Root Development

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    Shoot and root development of the grass tiller is presented as a series of events on the tiller axis. Leaf, tiller bud, true stem, and root development are successive events in the life cycle of a single phytomer and the tiller is a co-ordinated series of phytomers, successive phytomers being progressively more advanced than the previous phytomer. In reviewing the individual growth processes of leaf, tiller, true stem, and root formation, fundamental determinants of light and nutrient capture are examined and examples presented to illustrate the link between component processes, plant morphogenesis, and plant performance. An example of the application of this understanding in plant improvement is given

    Is early center-based child care associated with tantrums and unmanageable behavior over time up to school entry?

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    Background. Existing research suggests that there is a relationship between greater exposure to center-based child care and child behavioral problems though the mechanism for the impact is unclear. However the measure used to document child care has usually been average hours, which may be particularly unreliable in the early months when fewer children are in center care. In addition individual trajectories for behavior difficulties have not been studied. Objective. The purpose of the current study was to examine whether the extent of exposure to center-based child care before two years predicted the trajectory of children’s difficult behavior (i.e., tantrums and unmanageable behavior) from 30 to 51 months controlling for child and maternal characteristics. Method. Data were drawn from UK-based Families, Children and Child Care (FCCC) study (n=1201). Individual growth models were fitted to test the relation between early center-based child care experiences and subsequent difficult behavior. Results. Children with more exposure to center-based care before two had less difficult behavior at 30 months, but more increase over time. Initial levels were predicted by higher difficult temperament and lower verbal ability. Higher difficult temperament and lower family socio-economic status predicted its change over time. Conclusion. Findings suggest that early exposure to center-based care before two years old is a risk factor for subsequent behavior problems especially when children have a longer period of exposure. A possible explanatory process is that child coping strategies to manage frustration are less well developed in a group context, especially when they lag behind in expressive language

    Functional estrogen receptors of red blood cells. Do they influence intracellular signaling?

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    Background/Aims: Estrogen could play a key role in the mechanisms underlying sex-related disparity in the incidence of thrombotic events. We investigated whether estrogen receptors (ERs) were expressed in human red blood cells (RBCs), and if they affected cell signaling of erythrocyte constitutive isoform of endothelial NO-synthase (eNOS) and nitric oxide (NO) release. Methods: RBCs from 29 non-smoker volunteers (15 males and 14 females) aged between 20 and 40 years were analyzed by cytometry and western blot. In particular, content and distribution of ER-α and ER-ÎČ, tyrosine kinases and eNOS phosphorylation and NO release were analyzed. Results: We demonstrated that: i) both ER-α and ER-ÎČ were expressed by RBCs; ii) they were both functionally active; and iii) ERs distribution and function were different in males and females. In particular, ERs modulated eNOS phosphorylation and NO release in RBCs from both sexes, but they induced the phosphorylation of specific tyrosine residues of kinases linked to eNOS activation and NO release in the RBCs from females only. Conclusion: Collectively, these data suggest that ERs could play a critical role in RBC intracellular signaling. The possible implication of this signaling in sex-linked risk disparity in human cardiovascular diseases, e.g. in thrombotic events, may not be ruled out

    Survival and critical care use among people with dementia in a large English cohort

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    BACKGROUND: Admitting people with dementia to critical care units may not always lead to a clear survival benefit. Critical care admissions of people with dementia vary across countries. Little is known about the use and trends of critical care admissions of people with dementia in England. OBJECTIVE: To investigate critical care use and survival among people with dementia in a large London catchment area. METHODS: A retrospective cohort study using data from dementia assessment services in south London, UK (2007-20) linked with national hospitalisation data to ascertain critical care admissions. Outcomes included age-sex-standardised critical care use and 1-year post-critical care admission survival by dementia severity (binary: mild versus moderate/severe). We used logistic regression and Kaplan-Meier survival plots for investigating 1-year survival following a critical care admission and linear regressions for time trends. RESULTS: Of 19,787 people diagnosed with dementia, 726 (3.7%) had ≄1 critical care admission at any time after receiving their dementia diagnosis. The overall 1-year survival of people with dementia, who had a CCA, was 47.5% (n = 345). Dementia severity was not associated with 1-year survival following a critical care admission (mild dementia versus moderate-severe dementia odds of 1-year mortality OR: 0.90, 95% CI [0.66-1.22]). Over the 12-year period from 2008 to 2019, overall critical care use decreased (ÎČ = -0.05; 95% CI = -0.01, -0.0003; P = 0.03), while critical care admissions occurring during the last year of life increased (ÎČ = 0.11, 95% CI = 0.01, 0.20, P = 0.03). CONCLUSIONS: In this cohort, while critical care use among people with dementia declined overall, its use increased among those in their last year of life. Survival remains comparable to that observed in general older populations

    Cognitive stimulation therapy for dementia: provision in National Health Service settings in England, Scotland and Wales

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    Objectives: Cognitive stimulation therapy (CST) is a brief, non-pharmacological intervention for people with dementia, with an established evidence base for improving cognition and quality of life. It is widely implemented in National Health Service (NHS) settings, but little is known about its naturalistic use. The aim of this survey was to identify and explore inclusion criteria, dose and quality of CST across services in Great Britain (England, Scotland and Wales). Methods: All NHS memory clinics and services for people with dementia were contacted and asked to complete a mixed methods online survey on CST delivery in their service. Questions were centred on who provided CST, who received CST, the dose of CST and any outcomes that were routinely measured. Results: A total of 57/186 services responded, giving a response rate of 30.7%. While the majority reported offering CST (87.7%), there was variability in how this was delivered. Differing inclusion criteria included the use of varying cognitive and behavioural outcome measures, and CST was reported as being offered once and twice weekly. Services also differed in how they evaluated the quality of CST and how this evidence was incorporated for future sessions. Conclusion: While there was a low response rate, this survey indicates that there is significant variability in how CST is used in clinical practice, with many trusts not adhering to the evidence base. To ensure that people with dementia are consistently offered evidence-based, high-quality CST across NHS settings, further standardisation of inclusion criteria, dose and outcomes is needed

    Serum clara cell protein: a sensitive biomarker of increased lung epithelium permeability caused by ambient ozone.

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    Ozone in ambient air may cause various effects on human health, including decreased lung function, asthma exacerbation, and even premature mortality. These effects have been evidenced using various clinical indicators that, although sensitive, do not specifically evaluate the O(3)-increased lung epithelium permeability. In the present study, we assessed the acute effects of ambient O(3) on the pulmonary epithelium by a new approach relying on the assay in serum of the lung-specific Clara cell protein (CC16 or CC10). We applied this test to cyclists who exercised for 2 hr during episodes of photochemical smog and found that O(3) induces an early leakage of lung Clara cell protein. The protein levels increased significantly into the serum from exposure levels as low as 0.060-0.084 ppm. Our findings, confirmed in mice exposed to the current U.S. National Ambient Air Quality Standards for O(3) (0.08 ppm for 8 hr) indicate that above the present natural background levels, there is almost no safety margin for the effects of ambient O(3) on airway permeability. The assay of CC16 in the serum represents a new sensitive noninvasive test allowing the detection of early effects of ambient O(3) on the lung epithelial barrier

    Cultivating equality: delivering just and sustainable food systems in a changing climate

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    T oday, the world faces a greater challenge perhaps than ever before: tackling hunger and malnutrition in the face of climate change and increasing natural resource scarcity. Civil society, governments, researchers, donors, and the private sector are simultaneously debating and collaborating to find solutions. But the dialogue is over-emphasizing food production. Improving yields is important, particularly in places where there is not enough food or where food producers live in poverty. But simply producing more is not enough to tackle hunger. Furthermore, acknowledging that lack of food is not the sole cause of hunger is important. Inequality shapes who has access to food and the resources to grow it and buy it. It governs who eats first and who eats worst. Inequality determines who can adapt more readily to a changing climate. Hunger and poverty are not an accident – they are the result of social and economic injustice and inequality at all levels, from household to global. The reality of inequality is no truer for anyone than it is for women – half the world’s population, with far less than their fair share of the world’s resources. If we are to achieve the new Sustainable Development Goal of ending hunger by 2030, we must address the underlying inequalities in food systems. In a changing climate, agriculture and food systems must be sustainable and productive – but our efforts cannot end there. They must be profitable for those for whom it is a livelihood; they must be equitable, to facilitate a level playing field in the market, to secure rights to resources for food producers, and to ensure access to nutritious food for all; they must be resilient to build the capacity of populations vulnerable to economic shocks, political instability, and increasing, climate-induced natural hazards to recover and still lift themselves out of poverty
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