THE COSMIC/FORMOSAT-3 MISSION Anthes, R. A.; Bernhardt, P. A.; Chen, Y. ...
Bulletin of the American Meteorological Society,
03/2008, Letnik:
89, Številka:
3
Journal Article
Recenzirano
The radio occultation (RO) technique, which makes use of radio signals transmitted by the global positioning system (GPS) satellites, has emerged as a powerful and relatively inexpensive approach for ...sounding the global atmosphere with high precision, accuracy, and vertical resolution in all weather and over both land and ocean. On 15 April 2006, the joint Taiwan–U.S. Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC)/Formosa Satellite Mission 3 (COSMIC/FORMOSAT-3, hereafter COSMIC) mission, a constellation of six microsatellites, was launched into a 512-km orbit. After launch the satellites were gradually deployed to their final orbits at 800 km, a process that took about 17 months. During the early weeks of the deployment, the satellites were spaced closely, offering a unique opportunity to verify the high precision of RO measurements. As of September 2007, COSMIC is providing about 2000 RO soundings per day to support the research and operational communities. COSMIC RO data are of better quality than those from the previous missions and penetrate much farther down into the troposphere; 70%–90% of the soundings reach to within 1 km of the surface on a global basis. The data are having a positive impact on operational global weather forecast models.
With the ability to penetrate deep into the lower troposphere using an advanced open-loop tracking technique, the COSMIC RO instruments can observe the structure of the tropical atmospheric boundary layer. The value of RO for climate monitoring and research is demonstrated by the precise and consistent observations between different instruments, platforms, and missions. COSMIC observations are capable of intercalibrating microwave measurements from the Advanced Microwave Sounding Unit (AMSU) on different satellites. Finally, unique and useful observations of the ionosphere are being obtained using the RO receiver and two other instruments on the COSMIC satellites, the tiny ionosphere photometer (TIP) and the tri-band beacon.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Soil moisture dynamics reflect the complex interactions of meteorological conditions with soil, vegetation and terrain properties. In this study, intermediate-scale soil moisture estimates from the ...cosmic-ray neutron sensing (CRNS) method are evaluated for two semiarid ecosystems in the southwestern United States: a mesquite savanna at the Santa Rita Experimental Range (SRER) and a mixed shrubland at the Jornada Experimental Range (JER). Evaluations of the CRNS method are performed for small watersheds instrumented with a distributed sensor network consisting of soil moisture sensor profiles, an eddy covariance tower, and runoff flumes used to close the water balance. We found a very good agreement between the CRNS method and the distributed sensor network (root mean square error (RMSE) of 0.009 and 0.013 m(3)m(-3) at SRER and JER, respectively) at the hourly timescale over the 19-month study period, primarily due to the inclusion of 5 cm observations of shallow soil moisture. Good agreement was also obtained in soil moisture changes estimated from the CRNS and watershed water balance methods (RMSE of 0.001 and 0.082 m(3) m(-3) at SRER and JER, respectively), with deviations due to bypassing of the CRNS measurement depth during large rainfall events. Once validated, the CRNS soil moisture estimates were used to investigate hydrological processes at the footprint scale at each site. Through the computation of the water balance, we showed that drier-than-average conditions at SRER promoted plant water uptake from deeper soil layers, while the wetter-than-average period at JER resulted in percolation towards deeper soils. The CRNS measurements were then used to quantify the link between evapotranspiration and soil moisture at a commensurate scale, finding similar predictive relations at both sites that are applicable to other semiarid ecosystems in the southwestern US.
An improved understanding of the drivers controlling infiltration patterns in semiarid regions is of key importance, as they have important implications for ecosystem productivity, retention of ...resources and the restoration of degraded areas. The infiltration depth variability (ΔInf) in vegetation patches at the hillslope scale can be driven by different factors along the hillslope. Here we investigate the effects of vegetation and terrain attributes under hypothesis that these attributes exert a major control in ΔInf within the patches. We characterise the ΔInf within vegetation patches at a semiarid hillslope located at the Jornada Experimental Range at dry antecedent conditions preceding two winter frontal rainfall events. We measured these events that are typical during winter conditions, and are characterised by low intensity (0.67 and 4.48 mm h−1) and a total rainfall of 10.4 and 4.6 mm. High precision geo-referenced wetting front depth measurements were taken at various locations within the vegetation patches using differential GPS. Vegetation and terrain attributes were analysed to explain the ΔInf among the vegetation patches. The infiltration depths in the periphery of the patches were in general considerably deeper than those in the centre. The observations suggest that the upslope margin of the patches received additional water in the form of runon from upslope adjacent bare soil. Patch orientation with regard to the slope dictated the effect of the rest of the patch attributes and the distance to the hillslope crest on ΔInf. We found that primarily patch orientation, followed by shape and size modulate lateral surface water transport through their effects on overland flow paths and water retention; something that would be obscured under more simplistic characterisations based on bare versus uniform vegetated soil discrimination.
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•Vegetation and terrain affect spatial variation in shallow infiltration depth.•Measurement of wetting front depths at various locations within vegetation patches•Infiltration depths are variable within the vegetation patches.•Infiltration variability is controlled by patch orientation, shape and terrain.•Patch orientation dictates patch shape and distance to hillslope crest effect.
Mountainous regions act as the water towers of the world
by producing streamflow and groundwater recharge, a function that is
particularly important in semiarid regions. Quantifying rates of mountain
...system recharge is difficult, and hydrologic models offer a method to
estimate recharge over large scales. These recharge estimates are prone to
uncertainty from various sources including model structure and parameters.
The quality of meteorological forcing datasets, particularly in mountainous
regions, is a large source of uncertainty that is often neglected in
groundwater investigations. In this contribution, we quantify the impact of
uncertainty in both precipitation and air temperature forcing datasets on
the simulated groundwater recharge in the mountainous watershed of the
Kaweah River in California, USA. We make use of the integrated surface water–groundwater model, ParFlow.CLM, and several gridded datasets commonly used
in hydrologic studies, downscaled NLDAS-2, PRISM, Daymet, Gridmet, and
TopoWx. Simulations indicate that, across all forcing datasets, mountain front recharge is an important component of the water budget in the
mountainous watershed, accounting for 9 %–72 % of the annual precipitation and ∼90 % of the total mountain system recharge to the
adjacent Central Valley aquifer. The uncertainty in gridded air temperature
or precipitation datasets, when assessed individually, results in similar
ranges of uncertainty in the simulated water budget. Variations in simulated
recharge to changes in precipitation (elasticities) and air temperature
(sensitivities) are larger than 1 % change in recharge per 1 % change in
precipitation or 1 ∘C change in temperature. The total volume of
snowmelt is the primary factor creating the high water budget sensitivity, and snowmelt volume is influenced by both precipitation and air temperature
forcings. The combined effect of uncertainty in air temperature and
precipitation on recharge is additive and results in uncertainty levels roughly equal to the sum of the individual uncertainties depending on the
hydroclimatic condition of the watershed. Mountain system recharge pathways
including mountain block recharge, mountain aquifer recharge, and mountain
front recharge are less sensitive to changes in air temperature than changes
in precipitation. Mountain front and mountain block recharge are more
sensitive to changes in precipitation than other recharge pathways. The
magnitude of uncertainty in the simulated water budget reflects the
importance of developing high-quality meteorological forcing datasets in mountainous regions.
Objective To use the rs1229984 variant in the alcohol dehydrogenase 1B gene (ADH1B) as an instrument to investigate the causal role of alcohol in cardiovascular disease. Design Mendelian ...randomisation meta-analysis of 56 epidemiological studies. Participants 261 991 individuals of European descent, including 20 259 coronary heart disease cases and 10 164 stroke events. Data were available on ADH1B rs1229984 variant, alcohol phenotypes, and cardiovascular biomarkers. Main outcome measures Odds ratio for coronary heart disease and stroke associated with the ADH1B variant in all individuals and by categories of alcohol consumption. Results Carriers of the A-allele of ADH1B rs1229984 consumed 17.2% fewer units of alcohol per week (95% confidence interval 15.6% to 18.9%), had a lower prevalence of binge drinking (odds ratio 0.78 (95% CI 0.73 to 0.84)), and had higher abstention (odds ratio 1.27 (1.21 to 1.34)) than non-carriers. Rs1229984 A-allele carriers had lower systolic blood pressure (−0.88 (−1.19 to −0.56) mm Hg), interleukin-6 levels (−5.2% (−7.8 to −2.4%)), waist circumference (−0.3 (−0.6 to −0.1) cm), and body mass index (−0.17 (−0.24 to −0.10) kg/m2). Rs1229984 A-allele carriers had lower odds of coronary heart disease (odds ratio 0.90 (0.84 to 0.96)). The protective association of the ADH1B rs1229984 A-allele variant remained the same across all categories of alcohol consumption (P=0.83 for heterogeneity). Although no association of rs1229984 was identified with the combined subtypes of stroke, carriers of the A-allele had lower odds of ischaemic stroke (odds ratio 0.83 (0.72 to 0.95)). Conclusions Individuals with a genetic variant associated with non-drinking and lower alcohol consumption had a more favourable cardiovascular profile and a reduced risk of coronary heart disease than those without the genetic variant. This suggests that reduction of alcohol consumption, even for light to moderate drinkers, is beneficial for cardiovascular health.
•Experimental and theoretical analysis of the anomalous Hall effect in MnGa thin films.•DFT calculations were performed to determine the intrinsic Berry curvature.•Intrinsic Berry curvature results ...in an anomalous Hall conductivity of 127(Ωcm)−1.•Side-jump contribution can be enhanced by the thermal activation mechanisms.
We report on resistivity and Hall effect in MnGa thin films grown by molecular beam epitaxy on GaAs substrates. Highly (111)-textured MnGa film with L10 structure exhibits hard magnetic properties with coercivities as high as 20kOe and spin disorder mechanisms contributing to the Hall conductivity at room temperature. Density functional theory calculations were performed to determine the intrinsic Berry curvature in the momentum space with chiral spin structure that results in an anomalous Hall conductivity of 127(Ωcm)−1 comparable to that measured at low temperature. In addition to residual and side-jump contributions, which are enhanced by thermal activation, both anomalous Hall conductivity and Hall angle increase between 100K and room temperature. The present results reinforce the potential of Mn-Ga system for developing Hall effect-based spintronic devices.
Background and purpose
Basilar artery occlusion (BAO) leads to high rates of morbidity and mortality, despite successful recanalization. The discordance between flow restoration and long‐term ...functional status clouds clinical decision‐making regarding further aggressive care. We sought to develop and validate a practical, prognostic tool for the prediction of 3‐month favorable outcome after acute reperfusion therapy for BAO.
Methods
This retrospective, multicenter, observational study was conducted at four high‐volume stroke centers in the USA and Europe. Multivariate regression analysis was performed to identify predictors of favorable outcome (90‐day modified Rankin scale scores 0–2) and derive a clinically applicable prognostic model (the Pittsburgh Outcomes after Stroke Thrombectomy‐Vertebrobasilar (POST‐VB) score). The POST‐VB score was evaluated and internally validated with regard to calibration and discriminatory ability. External validity was assessed in patient cohorts at three separate centers.
Results
In the derivation cohort of 59 patients, independent predictors of favorable outcome included smaller brainstem infarct volume on post‐procedure magnetic resonance imaging (P < 0.01) and younger age (P = 0.01). POST‐VB score was calculated as: age + (10 × brainstem infarct volume). POST‐VB score demonstrated excellent discriminatory ability area under the receiver‐operating characteristic curve (AUC) = 0.91 and adequate calibration (P = 0.88) in the derivation cohort (Center A). It performed equally well across the three external validation cohorts (Center B, AUC = 0.89; Center C, AUC = 0.78; Center D, AUC = 0.80). Overall, a POST‐VB score < 49 was associated with an 88% likelihood of favorable outcome, as compared to 4% with a score ≥ 125.
Conclusions
The POST‐VB score effectively predicts 3‐month functional outcome following acute reperfusion therapy for BAO and may aid in guiding post‐procedural care.
Summary Background Statins increase the risk of new-onset type 2 diabetes mellitus. We aimed to assess whether this increase in risk is a consequence of inhibition of 3-hydroxy-3-methylglutaryl-CoA ...reductase (HMGCR), the intended drug target. Methods We used single nucleotide polymorphisms in the HMGCR gene, rs17238484 (for the main analysis) and rs12916 (for a subsidiary analysis) as proxies for HMGCR inhibition by statins. We examined associations of these variants with plasma lipid, glucose, and insulin concentrations; bodyweight; waist circumference; and prevalent and incident type 2 diabetes. Study-specific effect estimates per copy of each LDL-lowering allele were pooled by meta-analysis. These findings were compared with a meta-analysis of new-onset type 2 diabetes and bodyweight change data from randomised trials of statin drugs. The effects of statins in each randomised trial were assessed using meta-analysis. Findings Data were available for up to 223 463 individuals from 43 genetic studies. Each additional rs17238484-G allele was associated with a mean 0·06 mmol/L (95% CI 0·05–0·07) lower LDL cholesterol and higher body weight (0·30 kg, 0·18–0·43), waist circumference (0·32 cm, 0·16–0·47), plasma insulin concentration (1·62%, 0·53–2·72), and plasma glucose concentration (0·23%, 0·02–0·44). The rs12916 SNP had similar effects on LDL cholesterol, bodyweight, and waist circumference. The rs17238484-G allele seemed to be associated with higher risk of type 2 diabetes (odds ratio OR per allele 1·02, 95% CI 1·00–1·05); the rs12916-T allele association was consistent (1·06, 1·03–1·09). In 129 170 individuals in randomised trials, statins lowered LDL cholesterol by 0·92 mmol/L (95% CI 0·18–1·67) at 1-year of follow-up, increased bodyweight by 0·24 kg (95% CI 0·10–0·38 in all trials; 0·33 kg, 95% CI 0·24–0·42 in placebo or standard care controlled trials and −0·15 kg, 95% CI −0·39 to 0·08 in intensive-dose vs moderate-dose trials) at a mean of 4·2 years (range 1·9–6·7) of follow-up, and increased the odds of new-onset type 2 diabetes (OR 1·12, 95% CI 1·06–1·18 in all trials; 1·11, 95% CI 1·03–1·20 in placebo or standard care controlled trials and 1·12, 95% CI 1·04–1·22 in intensive-dose vs moderate dose trials). Interpretation The increased risk of type 2 diabetes noted with statins is at least partially explained by HMGCR inhibition. Funding The funding sources are cited at the end of the paper.
Background:
Bone mineral density (BMD) in adult patients with Prader-Willi syndrome (PWS) might be low due to high bone turnover.
Objectives:
The objective of the study was to investigate bone mass ...in a group of adult PWS subjects and study the effects of GH treatment on BMD and markers of bone turnover.
Design:
Forty-six adults with genetically verified PWS were randomized to GH or placebo for 12 months, followed by open prospective GH for 24 additional months. BMD at the lumbar spine (LS) L1–4, the total hip, and the total body was assessed by dual-energy x-ray absorptiometry at baseline and every 12th month thereafter. Markers of bone turnover were measured at baseline and at the end of the controlled study.
Results:
In this cohort of adult subjects with PWS, baseline BMD was reduced in all compartments compared with the reference (Z-scores). Men had lower Z-scores BMD than women in LS and total body (P < .05). With 12 months of GH, LS-BMD was significantly reduced compared with placebo. No changes in BMD were observed with continuous GH treatment for 24 months. The bone formation markers increased with GH therapy compared with placebo, whereas the resorption marker did not change.
Conclusions:
Adult PWS subjects, especially the men, have low bone mass that was not improved with GH treatment for 2 years. Because PWS subjects are short, BMD might be underestimated and should be adjusted for. Further studies, with adequate GH and sex hormone replacement throughout puberty and early adult life, are needed to better characterize PWS.
Understanding the clinical pharmacology of the antifibrinolytic epsilon-aminocaproic acid (EACA) is necessary for rational drug administration in children. The aim of this study is to determine the ...pharmacokinetics (PKs) of EACA in infants aged 6–24 months undergoing craniofacial reconstruction surgery.
Cohorts of six infants were enrolled sequentially to one of the three escalating loading dose–continuous i.v. infusion (CIVI) regimens: 25 mg kg−1, 10 mg kg−1 h−1; 50 mg kg−1, 20 mg kg−1 h−1; 100 mg kg−1, 40 mg kg−1 h−1. Plasma EACA concentrations were determined using a validated high-performance liquid chromatography-tandem mass spectrometry assay. A population non-linear mixed effects modelling approach was used to characterize EACA PKs.
Population PK parameters of EACA were estimated using a two-compartment disposition model with weight expressed as an allometric covariate and an age effect. The typical patient in this study had an age of 38.71 weeks and a weight of 8.82 kg. PK parameters for this typical patient were: pre-/postoperative plasma drug clearance of 32 ml min−1 (3.6 ml kg−1 min−1), inter-compartmental clearance of 42.4 ml min−1 (4.8 ml min−1 kg−1), central volume of distribution of 1.27 litre (0.14 litre kg−1), and peripheral volume of distribution of 2.53 litre (0.29 litre kg−1). Intra-operative clearance and central volume of distribution were 89% and 80% of the pre-/postoperative value, respectively.
EACA clearance increased with weight and age. The dependence of clearance on body weight supports weight-based dosing. Based on this study, a loading dose of 100 mg kg−1 followed by a CIVI of 40 mg kg−1 h−1 is appropriate to maintain target plasma EACA concentrations in children aged 6–24 months undergoing these procedures.
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