3,736 research outputs found

    Ecophysiological traits of grasses: resolving the effects of photosynthetic pathway and phylogeny

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    C4 photosynthesis is an important example of convergent evolution in plants, having arisen in eudicots, monocots and diatoms. Comparisons between such diverse groups are confounded by phylogenetic and ecological differences, so that only broad generalisations can be made about the role of C4 photosynthesis in
determining ecophysiological traits. However, 60% of C4 species occur in the grasses (Poaceae) and molecular phylogenetic techniques confirm that there are between 8 and 17 independent origins of C4 photosynthesis in the Poaceae. In a screening experiment, we compared leaf physiology and growth traits across several major
independent C3 & C4 groups within the Poaceae, asking 1) which traits differ consistently between photosynthetic
types and 2) which traits differ consistently between clades within each photosynthetic type

    Snakebite: An Exploratory Cost-Effectiveness Analysis of Adjunct Treatment Strategies.

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    The cost-effectiveness of the standard of care for snakebite treatment, antivenom, and supportive care has been established in various settings. In this study, based on data from South Indian private health-care providers, we address an additional question: "For what cost and effectiveness values would adding adjunct-based treatment strategies to the standard of care for venomous snakebites be cost-effective?" We modeled the cost and performance of potential interventions (e.g., pharmacologic or preventive) used adjunctively with antivenom and supportive care for the treatment of snakebite. Because these potential interventions are theoretical, we used a threshold cost-effectiveness approach to explore this forward-looking concept. We examined economic parameters at which these interventions could be cost-effective or even cost saving. A threshold analysis was used to examine the addition of new interventions to the standard of care. Incremental cost-effectiveness ratios were used to compare treatment strategies. One-way, scenario, and probabilistic sensitivity analyses were conducted to analyze parameter uncertainty and define cost and effectiveness thresholds. Our results suggest that even a 3% reduction in severe cases due to an adjunct strategy is likely to reduce the cost of overall treatment and have the greatest impact on cost-effectiveness. In this model, for example, an investment of 10ofinterventionthatreducestheincidenceofseverecasesby310 of intervention that reduces the incidence of severe cases by 3%, even without changing antivenom usage patterns, creates cost savings of 75 per individual. These findings illustrate the striking degree to which an adjunct intervention could improve patient outcomes and be cost-effective or even cost saving

    Financial Anxiety in Low- and Moderate-Income Households: Findings From the Household Financial Survey

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    Despite significant gains in the U.S. economy following the Great Recession, finances remain a common source of stress for many American households. In 2016, 52% of U.S. workers reported that their financial position made them stressed, and research reveals that stress and anxiety associated with finances are particularly common among low-income Americans. In this brief, we explore the topic of financial anxiety, particularly its relationship to demographic and financial characteristics, measures of hardship, and financial behaviors. We find that financial anxiety is strongly linked to the overall levels of debt and assets held by low-income households, as well as their ability to access resources in an emergency, but is not closely linked with income measures. Households incapable of saving due to their expenses and those experiencing material hardships also have higher levels of financial anxiety. Policymakers and program designers could help address this issue in several ways. For example, they might work to expand access to programs intended to provide financial slack to low-income households; assistance in building emergency savings and access to low-cost credit products would improve slack in these households while improving protection against income and expense volatility and its associated stresses

    The State of State EITCs: An Overview and Their Implications for Low- and Moderate-Income Households

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    The success of the federal Earned Income Tax Credit (EITC) has prompted numerous states to develop and administer their own EITC programs. This brief presents the results of analyses that used data from a large sample of low- and moderate-income households to learn more about the relationship between state and federal EITCs as well as about their relationships, respective and combined, with financial behaviors and the experience of financial and material hardship. Given that many EITC beneficiaries face substantial risk of experiencing income volatility and financial shocks, insights gained from this brief can assist policymakers in understanding the importance of expanded EITCs and promoting emergency saving at tax time

    Xrn1/Pacman affects apoptosis and regulates expression of hid and reaper

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    Programmed cell death, or apoptosis, is a highly conserved cellular process that is crucial for tissue homeostasis under normal development as well as environmental stress. Misregulation of apoptosis is linked to many developmental defects and diseases such as tumour formation, autoimmune diseases and neurological disorders. In this paper, we show a novel role for the exoribonuclease Pacman/Xrn1 in regulating apoptosis. Using Drosophila wing imaginal discs as a model system, we demonstrate that a null mutation in pacman results in small imaginal discs as well as lethality during pupation. Mutant wing discs show an increase in the number of cells undergoing apoptosis, especially in the wing pouch area. Compensatory proliferation also occurs in these mutant discs, but this is insufficient to compensate for the concurrent increase in apoptosis. The phenotypic effects of the pacman null mutation are rescued by a deletion that removes one copy of each of the pro-apoptotic genes reaper, hid and grim, demonstrating that pacman acts through this pathway. The null pacman mutation also results in a significant increase in the expression of the pro-apoptotic mRNAs, hid and reaper, with this increase mostly occurring at the post-transcriptional level, suggesting that Pacman normally targets these mRNAs for degradation. Our results uncover a novel function for the conserved exoribonuclease Pacman and suggest that this exoribonuclease is important in the regulation of apoptosis in other organisms

    Iterative Averaging in the Quest for Best Test Error

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    We analyse and explain the increased generalisation performance of iterate averaging using a Gaussian process perturbation model between the true and batch risk surface on the high dimensional quadratic. We derive three phenomena \latestEdits{from our theoretical results:} (1) The importance of combining iterate averaging (IA) with large learning rates and regularisation for improved regularisation. (2) Justification for less frequent averaging. (3) That we expect adaptive gradient methods to work equally well, or better, with iterate averaging than their non-adaptive counterparts. Inspired by these results\latestEdits{, together with} empirical investigations of the importance of appropriate regularisation for the solution diversity of the iterates, we propose two adaptive algorithms with iterate averaging. These give significantly better results compared to stochastic gradient descent (SGD), require less tuning and do not require early stopping or validation set monitoring. We showcase the efficacy of our approach on the CIFAR-10/100, ImageNet and Penn Treebank datasets on a variety of modern and classical network architectures
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