189 research outputs found
Mapping annual forest cover by fusing PALSAR/PALSAR-2 and MODIS NDVI during 2007–2016
Advanced Land Observing Satellite (ALOS) Phased Arrayed L-band Synthetic Aperture Radar (PALSAR) HH and HV polarization data were used previously to produce annual, global 25 m forest maps between 2007 and 2010, and the latest global forest maps of 2015 and 2016 were produced by using the ALOS-2 PALSAR-2 data. However, annual 25 m spatial resolution forest maps during 2011–2014 are missing because of the gap in operation between ALOS and ALOS-2, preventing the construction of a continuous, fine resolution time-series dataset on the world's forests. In contrast, the MODerate Resolution Imaging Spectroradiometer (MODIS) NDVI images were available globally since 2000. This research developed a novel method to produce annual 25 m forest maps during 2007–2016 by fusing the fine spatial resolution, but asynchronous PALSAR/PALSAR-2 with coarse spatial resolution, but synchronous MODIS NDVI data, thus, filling the four-year gap in the ALOS and ALOS-2 time-series, as well as enhancing the existing mapping activity. The method was developed concentrating on two key objectives: 1) producing more accurate 25 m forest maps by integrating PALSAR/PALSAR-2 and MODIS NDVI data during 2007–2010 and 2015–2016; 2) reconstructing annual 25 m forest maps from time-series MODIS NDVI images during 2011–2014. Specifically, a decision tree classification was developed for forest mapping based on both the PALSAR/PALSAR-2 and MODIS NDVI data, and a new spatial-temporal super-resolution mapping was proposed to reconstruct the 25 m forest maps from time-series MODIS NDVI images. Three study sites including Paraguay, the USA and Russia were chosen, as they represent the world's three main forest types: tropical forest, temperate broadleaf and mixed forest, and boreal conifer forest, respectively. Compared with traditional methods, the proposed approach produced the most accurate continuous time-series of fine spatial resolution forest maps both visually and quantitatively. For the forest maps during 2007–2010 and 2015–2016, the results had greater overall accuracy values (>98%) than those of the original JAXA forest product. For the reconstructed 25 m forest maps during 2011–2014, the increases in classifications accuracy relative to three benchmark methods were statistically significant, and the overall accuracy values of the three study sites were almost universally >92%. The proposed approach, therefore, has great potential to support the production of annual 25 m forest maps by fusing PALSAR/PALSAR-2 and MODIS NDVI during 2007–2016
Shoulder muscle activity in sport climbing in naturally chosen and corrected shoulder positions
Objective: The aim of the study was to determine electromyographic activity of the scapula stabilizing muscles in naturally chosen and corrected shoulder positions in typical static climbing postures. Methods: Six male participants undertook surface electromyography measurement in four climbing postures for two different shoulder positions. The activity of the lower, middle and upper trapezius, serratus anterior, pectoralis major, and sternocleidomastoid was recorded. Electromyographic activity was expressed as the percentage of maximal voluntary contraction (MVC) for each muscle. Results: Climbing postures induced higher activation of middle and lower trapezius in corrected shoulder positions (35.3 ± 11.8 and 61.7 ± 15.4% MVC respectively) than in naturally chosen shoulder positions (18.4 ± 8.9 and 30.1 ± 13.8% MVC respectively). The highest activity of the middle and lower trapezius was found in postures with the arm in external rotation and 90° abduction and in an overhanging posture. Low activation was stated for the other muscles in both shoulder conditions. Conclusion: Results showed that climbers naturally elevate the shoulder during typical static postures. Corrected shoulder positions induce higher activation of the scapula stabilizing muscles than naturally chosen shoulder positions.N/
Observation and Modeling of the Solar-Cycle Variation of the Meridional Flow
We present independent observations of the solar-cycle variation of flows
near the solar surface and at a depth of about 60 Mm, in the latitude range
. We show that the time-varying components of the meridional flow
at these two depths have opposite sign, while the time-varying components of
the zonal flow are in phase. This is in agreement with previous results. We
then investigate whether the observations are consistent with a theoretical
model of solar-cycle dependent meridional circulation based on a flux-transport
dynamo combined with a geostrophic flow caused by increased radiative loss in
the active region belt (the only existing quantitative model). We find that the
model and the data are in qualitative agreement, although the amplitude of the
solar-cycle variation of the meridional flow at 60 Mm is underestimated by the
model.Comment: To be published in Solar Physcis Topical Issue "Helioseismology,
Asteroseismology, and MHD Connections
Time--Distance Helioseismology Data Analysis Pipeline for Helioseismic and Magnetic Imager onboard Solar Dynamics Observatory (SDO/HMI) and Its Initial Results
The Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory
(SDO/HMI) provides continuous full-disk observations of solar oscillations. We
develop a data-analysis pipeline based on the time-distance helioseismology
method to measure acoustic travel times using HMI Doppler-shift observations,
and infer solar interior properties by inverting these measurements. The
pipeline is used for routine production of near-real-time full-disk maps of
subsurface wave-speed perturbations and horizontal flow velocities for depths
ranging from 0 to 20 Mm, every eight hours. In addition, Carrington synoptic
maps for the subsurface properties are made from these full-disk maps. The
pipeline can also be used for selected target areas and time periods. We
explain details of the pipeline organization and procedures, including
processing of the HMI Doppler observations, measurements of the travel times,
inversions, and constructions of the full-disk and synoptic maps. Some initial
results from the pipeline, including full-disk flow maps, sunspot subsurface
flow fields, and the interior rotation and meridional flow speeds, are
presented.Comment: Accepted by Solar Physics topical issue 'Solar Dynamics Observatory
Measurement of the branching fraction for
We have studied the leptonic decay of the resonance into tau
pairs using the CLEO II detector. A clean sample of tau pair events is
identified via events containing two charged particles where exactly one of the
particles is an identified electron. We find . The result is consistent with
expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS
94/1297, CLEO 94-20 (submitted to Physics Letters B
Subsurface Meridional Circulation in the Active Belts
Temporal variations of the subsurface meridional flow with the solar cycle
have been reported by several authors. The measurements are typically averaged
over periods of time during which surface magnetic activity existed in the
regions were the velocities are calculated. The present work examines the
possible contamination of these measurements due to the extra velocity fields
associated with active regions plus the uncertainties in the data obtained
where strong magnetic fields are present. We perform a systematic analysis of
more than five years of GONG data and compare meridional flows obtained by
ring-diagram analysis before and after removing the areas of strong magnetic
field. The overall trend of increased amplitude of the meridional flow towards
solar minimum remains after removal of large areas associated with surface
activity. We also find residual circulation toward the active belts that
persist even after the removal of the surface magnetic activity, suggesting the
existence of a global pattern or longitudinally-located organized flows.Comment: 12 pages, 6 figures, Submitted to Solar Physics. Accepted
(08/25/2008
Methotrexate-related central neurotoxicity: clinical characteristics, risk factors and genome-wide association study in children treated for acute lymphoblastic leukemia
Symptomatic methotrexate-related central neurotoxicity (MTX neurotoxicity) is a severe toxicity experienced during acute lymphoblastic leukemia (ALL) therapy with potential long-term neurologic complications. Risk factors and long-term outcomes require further study. We conducted a systematic, retrospective review of 1,251 consecutive Australian children enrolled on Berlin-Frankfurt-Münster or Children's Oncology Group-based protocols between 1998-2013. Clinical risk predictors for MTX neurotoxicity were analyzed using regression. A genome-wide association study (GWAS) was performed on 48 cases and 537 controls. The incidence of MTX neurotoxicity was 7.6% (n=95 of 1,251), at a median of 4 months from ALL diagnosis and 8 days after intravenous or intrathecal MTX. Grade 3 elevation of serum aspartate aminotransferase (P=0.005, odds ratio 2.31 [range, 1.28–4.16]) in induction/consolidation was associated with MTX neurotoxicity, after accounting for the only established risk factor, age ≥10 years. Cumulative incidence of CNS relapse was increased in children where intrathecal MTX was omitted following symptomatic MTX neurotoxicity (n=48) compared to where intrathecal MTX was continued throughout therapy (n=1,174) (P=0.047). Five-year central nervous system relapse-free survival was 89.2±4.6% when intrathecal MTX was ceased compared to 95.4±0.6% when intrathecal MTX was continued. Recurrence of MTX neurotoxicity was low (12.9%) for patients whose intrathecal MTX was continued after their first episode. The GWAS identified single-nucletide polymorphism associated with MTX neurotoxicity near genes regulating neuronal growth, neuronal differentiation and cytoskeletal organization (P<1x10-6). In conclusion, increased serum aspartate aminotransferase and age ≥10 years at diagnosis were independent risk factors for MTX neurotoxicity. Our data do not support cessation of intrathecal MTX after a first MTX neurotoxicity event.Marion K. Mateos, Glenn M Marshall, Pasquale M. Barbaro, Michael C.J. Quinn, Carly George, Chelsea Mayoh, Rosemary Sutton, Tamas Revesz, Jodie E Giles, Draga Barbaric, Frank Alvaro, Françoise Mechinaud, Daniel Catchpoole, John A. Lawson, Georgia Chenevix-Trench, Stuart MacGregor, Rishi S.Kotecha, Luciano Dalla-Pozza, and Toby N. Traha
Genome-wide association meta-analysis of single-nucleotide polymorphisms and symptomatic venous thromboembolism during therapy for acute lymphoblastic leukemia and lymphoma in caucasian children
Symptomatic venous thromboembolism (VTE) occurs in five percent of children treated for acute lymphoblastic leukemia (ALL), but whether a genetic predisposition exists across different ALL treatment regimens has not been well studied.MethodsWe undertook a genome-wide association study (GWAS) meta-analysis for VTE in consecutively treated children in the Nordic/Baltic acute lymphoblastic leukemia 2008 (ALL2008) cohort and the Australian Evaluation of Risk of ALL Treatment-Related Side-Effects (ERASE) cohort. A total of 92 cases and 1481 controls of European ancestry were included.ResultsNo SNPs reached genome-wide significance (p -8) in either cohort. Among the top 34 single-nucleotide polymorphisms (SNPs) (p -6), two loci had concordant effects in both cohorts: ALOX15B (rs1804772) (MAF: 1%; p = 3.95 × 10-7) that influences arachidonic acid metabolism and thus platelet aggregation, and KALRN (rs570684) (MAF: 1%; p = 4.34 × 10-7) that has been previously associated with risk of ischemic stroke, atherosclerosis, and early-onset coronary artery disease.ConclusionThis represents the largest GWAS meta-analysis conducted to date associating SNPs to VTE in children and adolescents treated on childhood ALL protocols. Validation of these findings is needed and may then lead to patient stratification for VTE preventive interventions. As VTE hemostasis involves multiple pathways, a more powerful GWAS is needed to detect combination of variants associated with VTE.Marion K. Mateos, Morten Tulstrup, Michael CJ Quinn, Ruta Tuckuviene, Glenn M. Marshall, Ramneek Gupt
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Flowering plant communities mediate the effects of habitat composition and configuration on wild pollinator communities
1. There is strong evidence that landscape-scale factors such as habitat diversity, composition and configuration are important drivers of declines in pollinators and pollination services. However, context and species-specific responses make it challenging to draw general conclusions about the most important components of landscapes that support diverse and abundant pollinator communities.
2. In this study, we took a functional-traits approach to community assembly and tested the hypothesis that landscape properties act most strongly on pollinators indirectly, through their influence on flowering plant communities. Using plant and pollinator data from 96 landscapes in Britain, we tested the associations between plant and pollinator communities and local environmental factors, such as habitat cover and configuration, using path analysis based on Mantel and partial Mantel statistics.
3. When all pollinators were considered, we found that the environmental factors had stronger links to the composition of flowering plant communities than to the composition of pollinator communities. Further, the flowering plant community was strongly linked to the pollinator community suggesting a mediating role between land use and pollinators. When separating the pollinator community into taxonomic groups, we found the same result for hoverflies, but wild bees were linked to both environmental factors and flowering plants.
4. We further explored these links with structural equation models using the response-effect trait framework as a guiding principle. We found strong evidence that land-use composition and configuration influence the trait distribution and functional diversity of the pollinator community via plant community composition.
5. These findings suggest that the indirect effect of land use on pollinators via flowering plants should be considered in informing the design of pollinator friendly landscapes and in future research of the effects of land use and management on wild pollinators
Landscape-scale drivers of pollinator communities may depend on land-use configuration
Research into pollinators in managed landscapes has recently combined approaches of pollination ecology and landscape ecology, because key stressors are likely to interact across wide areas. While laboratory and field experiments are valuable for furthering understanding, studies are required to investigate the interacting drivers of pollinator health and diversity across a broader range of landscapes and a wider array of taxa. Here, we use a network of 96 study landscapes in six topographically diverse regions of Britain, to test the combined importance of honeybee density, insecticide loadings, floral resource availability and habitat diversity to pollinator communities. We also explore the interactions between these drivers and the cover and proximity of semi-natural habitat. We found that among our four drivers, only honeybee density was positively related to wild pollinator abundance and diversity, and the positive association between abundance and floral resources depended on insecticide loadings and habitat diversity. By contrast, our exploratory models including habitat composition metrics revealed a complex suite of interactive effects. These results demonstrate that improving pollinator community composition and health is unlikely to be achieved with general resource enhancements only. Rather, local land-use context should be considered in fine-tuning pollinator management and conservation
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