4,026 research outputs found

    The future of coffee and cocoa agroforestry in a warmer Mesoamerica

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    Climate change threatens cofee production and the livelihoods of thousands of families in Mesoamerica that depend on it. Replacing cofee with cocoa and integrating trees in combined agroforestry systems to ameliorate abiotic stress are among the proposed alternatives to overcome this challenge. These two alternatives do not consider the vulnerability of cocoa and tree species commonly used in agroforestry plantations to future climate conditions. We assessed the suitability of these alternatives by identifying the potential changes in the distribution of cofee, cocoa and the 100 most common agroforestry trees found in Mesoamerica. Here we show that cocoa could potentially become an alternative in most of cofee vulnerable areas. Agroforestry with currently preferred tree species is highly vulnerable to future climate change. Transforming agroforestry systems by changing tree species composition may be the best approach to adapt most of the cofee and cocoa production areas. Our results stress the urgency for land use planning considering climate change efects and to assess new combinations of agroforestry species in cofee and cocoa plantations in Mesoamerica

    Solving Lattice QCD systems of equations using mixed precision solvers on GPUs

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    Modern graphics hardware is designed for highly parallel numerical tasks and promises significant cost and performance benefits for many scientific applications. One such application is lattice quantum chromodyamics (lattice QCD), where the main computational challenge is to efficiently solve the discretized Dirac equation in the presence of an SU(3) gauge field. Using NVIDIA's CUDA platform we have implemented a Wilson-Dirac sparse matrix-vector product that performs at up to 40 Gflops, 135 Gflops and 212 Gflops for double, single and half precision respectively on NVIDIA's GeForce GTX 280 GPU. We have developed a new mixed precision approach for Krylov solvers using reliable updates which allows for full double precision accuracy while using only single or half precision arithmetic for the bulk of the computation. The resulting BiCGstab and CG solvers run in excess of 100 Gflops and, in terms of iterations until convergence, perform better than the usual defect-correction approach for mixed precision.Comment: 30 pages, 7 figure

    Individual tree detection and estimation of stem attributes with mobile laser scanning along boreal forest roads

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    The collection of field-reference data is a key task in remote sensing-based forest inventories. However, traditional methods of collection demand extensive personnel resources. Thus, field-reference data collection would benefit from more automated methods. In this study, we proposed a method for individual tree detection (ITD) and stem attribute estimation based on a car-mounted mobile laser scanner (MLS) operating along forest roads. We assessed its performance in six ranges with increasing mean distance from the roadside. We used a Riegl VUX1LR sensor operating with high repetition rate, thus providing detailed cross sections of the stems. The algorithm we propose was designed for this sensor configuration, identifying the cross sections (or arcs) in the point cloud and aggregating those into single trees. Furthermore, we estimated diameter at breast height (DBH), stem profiles, and stem volume for each detected tree. The accuracy of ITD, DBH, and stem volume estimates varied with the trees' distance from the road. In general, the proximity to the sensor of branches 0-10 m from the road caused commission errors in ITD and over estimation of stem attributes in this zone. At 50-60 m from roadside, stems were often occluded by branches, causing omissions and underestimation of stem attributes in this area. ITD's precision and sensitivity varied from 82.8% to 100% and 62.7% to 96.7%, respectively. The RMSE of DBH estimates ranged from 1.81 cm (6.38%) to 4.84 cm (16.9%). Stem volume estimates had RMSEs ranging from 0.0800 m(3) (10.1%) to 0.190 m(3) (25.7%), depending on the distance to the sensor. The average proportion of detected reference volume was highly affected by the performance of ITD in the different zones. This proportion was highest from 0 to 10 m (113%), a zone that concentrated most ITD commission errors, and lowest from 50 to 60 m (66.6%), mostly due to the omission errors in this area. In the other zones, the RMSE ranged from 87.5% to 98.5%. These accuracies are in line with those obtained by other state-of-the-art MLS and terrestrial laser scanner (TLS) methods. The car-mounted MLS system used has the potential to collect data efficiently in large-scale inventories, being able to scan approximately 80 ha of forests per day depending on the survey setup. This data collection method could be used to increase the amount of field-reference data available in remote sensing based forest inventories, improve models for area-based estimations, and support precision forestry development

    A Systematic Literature Review of the Humanistic Burden of COPD

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    Background: Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide, causing substantial economic and social burden. Objective: This review assessed the patient-reported humanistic burden associated with moderate to very severe COPD, specifically the impact on health-related quality of life (HRQoL), symptoms, limitations in daily life, and emotional implications, through the use of HRQoL instruments. Methods: A systematic review was conducted to retrieve relevant clinical data from published literature using a representative sample of countries where healthcare systems provide wide availability of COPD medications and/or universal coverage includes respiratory medicines (Australia, Canada, China, France, Germany, Italy, Spain, the UK, and the USA). The primary inclusion criteria were patients with moderate to very severe COPD. HRQoL was quantified with non-disease-specific and disease-specific questionnaires. Results: In total, 82 studies from 95 publications presented HRQoL data from patients with moderate to very severe COPD. Patient-reported HRQoL declined with worsening airflow limitation, advancing GOLD group, and increasing exacerbation frequency. Both increasing frequency of hospitalization for COPD exacerbations and recurrent hospitalization adversely impacted HRQoL. Comorbidity incidence was higher in patients with increased airflow limitation. It was associated with a further decline in HRQoL and increased depression and anxiety, particularly as disease-associated pain worsened. Physical activity improved HRQoL over time. Conclusion: This review highlighted the impact of exacerbations and associated hospitalizations on the humanistic burden of COPD. These findings underline the importance of managing COPD actively, including prompt and appropriate use of pharmacological and non-pharmacological therapies that can improve symptoms and reduce the risk of exacerbations, thereby lessening the humanistic burden. Future reviews could consider a broader range of countries and publications to further assess the humanistic impact of COPD in low- and middle-income economies

    Sodium flux ratio in Na/K pump-channels opened by palytoxin

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    © 2007 Rakowski et al. This article is distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License. The definitive version was published in Journal of General Physiology 130 (2007): 41-54, doi:10.1085/jgp.200709770.Palytoxin binds to Na+/K+ pumps in the plasma membrane of animal cells and opens an electrodiffusive cation pathway through the pumps. We investigated properties of the palytoxin-opened channels by recording macroscopic and microscopic currents in cell bodies of neurons from the giant fiber lobe, and by simultaneously measuring net current and 22Na+ efflux in voltage-clamped, internally dialyzed giant axons of the squid Loligo pealei. The conductance of single palytoxin-bound "pump-channels" in outside-out patches was ~7 pS in symmetrical 500 mM [Na+], comparable to findings in other cells. In these high-[Na+], K+-free solutions, with 5 mM cytoplasmic [ATP], the K0.5 for palytoxin action was ~70 pM. The pump-channels were ~40–50 times less permeable to N-methyl-D-glucamine (NMG+) than to Na+. The reversal potential of palytoxin-elicited current under biionic conditions, with the same concentration of a different permeant cation on each side of the membrane, was independent of the concentration of those ions over the range 55–550 mM. In giant axons, the Ussing flux ratio exponent (n') for Na+ movements through palytoxin-bound pump-channels, over a 100–400 mM range of external [Na+] and 0 to –40 mV range of membrane potentials, averaged 1.05 ± 0.02 (n = 28). These findings are consistent with occupancy of palytoxin-bound Na+/K+ pump-channels either by a single Na+ ion or by two Na+ ions as might be anticipated from other work; idiosyncratic constraints are needed if the two Na+ ions occupy a single-file pore, but not if they occupy side-by-side binding sites, as observed in related structures, and if only one of the sites is readily accessible from both sides of the membrane.This work was supported by NIH grants NS22979, NS11223, and HL36783, and National Science Foundation grant CCF- 0622158. This research was also partially funded by the Intra mural Research Program of the NIH, National Institute of Neurological Disorders and Stroke

    Modern Analysis Techniques for Spectroscopic Binaries

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    Techniques to extract information from spectra of unresolved multi-component systems are revised, with emphasis on recent developments and practical aspects. We review the cross-correlation techniques developed to deal with such spectra, discuss the determination of the broadening function and compare techniques to reconstruct component spectra. The recent results obtained by separating or disentangling the component spectra is summarized. An evaluation is made of possible indeterminacies and random and systematic errors in the component spectra.Comment: 12 pages, 3 figures, Invited talk to appear in the proceedings of IAU Symp. No. 240 'Binary Stars as Critical Tools and Tests in Contemporary Astrophysics' (Prague, 22-25 August 2006), Eds. W. Hartkopf, E. Guinan & P. Harmanec (Cambridge Univ. Press

    Short- and Long-Term Impact of Prior Chronic Obstructive Pulmonary Disease Exacerbations on Healthcare Resource Utilization and Related Costs : An Observational Study (SHERLOCK)

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    Acknowledgments Medical writing support, under the direction of the authors, was provided by Sara Cameron, MPhil, CMC Connect, a division of IPG Health Medical Communications, funded by AstraZeneca in accordance with Good Publication Practice (GPP 2022) guidelines [Citation28]. All authors were involved in the design and conduct of the study and in the interpretation of the data. All authors were involved in the writing of the manuscript and the final decision to submit to COPD: Journal of Chronic Obstructive Pulmonary Disease. Funding This study was sponsored by AstraZeneca. AstraZeneca authors were involved in the design of the study; in the analysis, and interpretation of the data; in the writing of the report; and in the decision to submit the article for publication.Peer reviewedPublisher PD
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