bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topographic influence on submesoscale dynamics in the Southern Ocean
Authors: Rosso Isabella , Hogg Andrew McC. , Kiss Andrew E. , Gayen Bishakhdatta 
Published: January 2015

AbstractTopography influences the circulation in the Southern Ocean, generating stationary meanders in the lee of topographic features, triggering hot spots of mesoscale eddy kinetic energy, and modifying jets and fronts. However, the relationship between topography and submesoscale flows (with length scales of order 1–10 km) has not yet been explored. The first submesoscale‐resolving (1/80° resolution) ocean model, with realistic topography of the Indian sector of the Southern Ocean, is used to investigate this interaction. The results show spatial inhomogeneity in submesoscale activity that is correlated with topography. Topographic influence is primarily indirect: topography controls mesoscale flows, which in turn generate submesoscale activity. Mesoscale eddy kinetic energy and strain rate can be used, to first order, to infer submesoscale vertical velocity, implying a possible route to parameterise submesoscale activity in coarser resolution models.
Central American biomass burning smoke can increase tornado severity in the U.S.
Authors: Saide P. E. , Spak S. N. , Pierce R. B. , Otkin J. A. , Schaack T. K. , Heidinger A. K. , da Silva A. M. , Kacenelenbogen M. , Redemann J. , Carmichael G. R. 
Published: January 2015

AbstractTornadoes in the Southeast and central U.S. are episodically accompanied by smoke from biomass burning in central America. Analysis of the 27 April 2011 historical tornado outbreak shows that adding smoke to an environment already conducive to severe thunderstorm development can increase the likelihood of significant tornado occurrence. Numerical experiments indicate that the presence of smoke during this event leads to optical thickening of shallow clouds while soot within the smoke enhances the capping inversion through radiation absorption. The smoke effects are consistent with measurements of clouds and radiation before and during the outbreak. These effects result in lower cloud bases and stronger low‐level wind shear in the warm sector of the extratropical cyclone generating the outbreak, two indicators of higher probability of tornadogenesis and tornado intensity and longevity. These mechanisms may contribute to tornado modulation by aerosols, highlighting the need to consider aerosol feedbacks in numerical severe weather forecasting.
Contrasting soil thermal responses to fire in Alaskan tundra and boreal forest
Authors: Jiang Yueyang , Rocha Adrian V. , O'Donnell Jonathan A. , Drysdale Jessica A. , Rastetter Edward B. , Shaver Gaius R. , Zhuang Qianlai 
Published: January 2015

AbstractRecent fire activity throughout Alaska has increased the need to understand postfire impacts on soils and permafrost vulnerability. Our study utilized data and modeling from a permafrost and ecosystem gradient to develop a mechanistic understanding of the short‐ and long‐term impacts of tundra and boreal forest fires on soil thermal dynamics. Fires influenced a variety of factors that altered the surface energy budget, soil moisture, and the organic‐layer thickness with the overall effect of increasing soil temperatures and thaw depth. The postfire thickness of the soil organic layer and its impact on soil thermal conductivity was the most important factor determining postfire soil temperatures and thaw depth. Boreal and tundra ecosystems underlain by permafrost experienced smaller postfire soil temperature increases than the nonpermafrost boreal forest from the direct and indirect effects of permafrost on drainage, soil moisture, and vegetation flammability. Permafrost decreased the loss of the insulating soil organic layer, decreased soil drying, increased surface water pooling, and created a significant heat sink to buffer postfire soil temperature and thaw depth changes. Ecosystem factors also played a role in determining postfire thaw depth with boreal forests taking several decades longer to recover their soil thermal properties than tundra. These factors resulted in tundra being less sensitive to postfire soil thermal changes than the nonpermafrost boreal forest. These results suggest that permafrost and soil organic carbon will be more vulnerable to fire as climate warms.
Unraveling bed slope from relative roughness in initial sediment motion
Authors: Prancevic Jeff P. , Lamb Michael P. 
Published: January 2015

AbstractUnderstanding incipient sediment transport is crucial for predicting landscape evolution, mitigating flood hazards, and restoring riverine habitats. Observations show that the critical Shields stress increases with increasing channel bed slope, and proposed explanations for this counterintuitive finding include enhanced form drag from bed forms, particle interlocking across the channel width, and large bed sediment relative to flow depth (relative roughness). Here we use scaled flume experiments with variable channel widths, bed slopes, and particle densities to separate these effects which otherwise covary in natural streams. The critical Shields stress increased with bed slope for both natural gravel (ρs = 2.65 g/cm3) and acrylic particles (ρs = 1.15 g/cm3), and adjusting channel width had no significant effect. However, the lighter acrylic particles required a threefold higher critical Shields stress for mobilization relative to the natural gravel at a fixed slope, which is unexpected because particle density is accounted for directly in the definition of Shields stress. A comparison with model predictions indicates that changes in local velocity and turbulence associated with increasing relative roughness for lighter materials are responsible for increasing the critical Shields stress in our experiments. These changes lead to concurrent changes in the hydraulic resistance and a nearly constant critical stream power value at initial motion. Increased relative roughness can explain much of the observed heightened critical Shields stresses and reduced sediment transport rates in steep channels and also may bias paleohydraulic reconstructions in environments with exotic submerged densities such as iron ore, pumice, or ice clasts on Titan.
Thermal boundary conditions on western Greenland: Observational constraints and impacts on the modeled thermomechanical state
Authors: Meierbachtol Toby W. , Harper Joel T. , Johnson Jesse V. , Humphrey Neil F. , Brinkerhoff Douglas J. 
Published: January 2015

AbstractThe surface and basal boundary conditions exert an important control on the thermodynamic state of the Greenland Ice Sheet, but their representation in numerical ice sheet models is poorly constrained due to the lack of observations. Here we investigate a land‐terminating sector of western Greenland and (1) quantify differences between new observations and commonly used boundary condition data sets and (2) demonstrate the impact of improved boundary conditions on simulated thermodynamics in a higher‐order numerical flow model. We constrain near‐surface temperature with measurements from two 20 m boreholes in the ablation zone and 10 m firn temperature from the percolation zone. We constrain basal heat flux using in situ measurement in a deep bedrock hole at the study area margin and other existing assessments. To assess boundary condition influences on simulated thermal‐mechanical processes, we compare model output to multiple full‐thickness temperature profiles collected in the ablation zone. Our observation‐constrained basal heat flux is 30 mW m−2 less than commonly used representations. In contrast, measured near‐surface temperatures are warmer than common surface temperature data sets by up to 15°C. Application of lower basal heat flux increases a model cold bias compared to the measured temperature profiles and causes frozen basal conditions across the ablation zone. Temperate basal conditions are reestablished by our warmer surface boundary. Warmer surface ice and firn can introduce several times more energy to the modeled ice mass than what is lost at the bed from reduced basal heat flux, indicating that the thermomechanical state of the ice sheet is highly sensitive to near‐surface effects.
Axial obliquity control on the greenhouse carbon budget through middle‐ to high‐latitude reservoirs
Authors: Laurin Jiří , Meyers Stephen R. , Uličný David , Jarvis Ian , Sageman Bradley B. 
Published: January 2015

AbstractCarbon sources and sinks are key components of the climate feedback system, yet their response to external forcing remains poorly constrained, particularly for past greenhouse climates. Carbon‐isotope data indicate systematic, million‐year‐scale transfers of carbon between surface reservoirs during and immediately after the Late Cretaceous thermal maximum (peaking in the Cenomanian‐Turonian, circa 97–91 million years, Myr, ago). Here we calibrate Albian to Campanian (108–72 Myr ago) high‐resolution carbon isotope records with a refined chronology and demonstrate how net transfers between reservoirs are plausibly controlled by ~1 Myr changes in the amplitude of axial obliquity. The amplitude‐modulating terms are absent from the frequency domain representation of insolation series and require a nonlinear, cumulative mechanism to become expressed in power spectra of isotope time series. Mass balance modeling suggests that the residence time of carbon in the ocean‐atmosphere system is—by itself—insufficient to explain the Myr‐scale variability. It is proposed that the astronomical control was imparted by a transient storage of organic matter or methane in quasi‐stable reservoirs (wetlands, soils, marginal zones of marine euxinic strata, and potentially permafrost) that responded nonlinearly to obliquity‐driven changes in high‐latitude insolation and/or meridional insolation gradients. While these reservoirs are probably underrepresented in the geological record due to their quasi‐stable character, they might have provided an important control on the dynamics and stability of the greenhouse climate.
The albedo of Earth
Authors: Stephens Graeme L. , O'Brien Denis , Webster Peter J. , Pilewski Peter , Kato Seiji , Li Jui‐lin 
Published: January 2015

AbstractThe fraction of the incoming solar energy scattered by Earth back to space is referred to as the planetary albedo. This reflected energy is a fundamental component of the Earth's energy balance, and the processes that govern its magnitude, distribution, and variability shape Earth's climate and climate change. We review our understanding of Earth's albedo as it has progressed to the current time and provide a global perspective of our understanding of the processes that define it. Joint analyses of surface solar flux data that are a complicated mix of measurements and model calculations with top‐of‐atmosphere (TOA) flux measurements from current orbiting satellites yield a number of surprising results including (i) the Northern and Southern Hemispheres (NH, SH) reflect the same amount of sunlight within ~ 0.2 W m−2. This symmetry is achieved by increased reflection from SH clouds offsetting precisely the greater reflection from the NH land masses. (ii) The albedo of Earth appears to be highly buffered on hemispheric and global scales as highlighted by both the hemispheric symmetry and a remarkably small interannual variability of reflected solar flux (~0.2% of the annual mean flux). We show how clouds provide the necessary degrees of freedom to modulate the Earth's albedo setting the hemispheric symmetry. We also show that current climate models lack this same degree of hemispheric symmetry and regulation by clouds. The relevance of this hemispheric symmetry to the heat transport across the equator is discussed.
Trends in Excess Mortality Among Patients With Rheumatoid Arthritis in Ontario, Canada
Authors: Widdifield Jessica , Bernatsky Sasha , Paterson J. Michael , Tomlinson George , Tu Karen , Kuriya Bindee , Thorne J. Carter , Pope Janet E. , Hollands Simon , Bombardier Claire 
Published: January 2015

ObjectiveTo evaluate excess mortality over time, comparing rheumatoid arthritis (RA) patients with the general population.MethodsWe computed all‐cause mortality rates among Ontario residents age ≥15 years with RA versus without RA from 1996 to 2009. Age‐ and sex‐standardized mortality rates were expressed as the number of deaths per 1,000 population. Excess mortality rates were calculated as the difference between death rates among RA patients and those in the general population. We estimated standardized mortality ratios (SMRs) and mortality rate ratios (MRRs) to assess relative excess mortality over time.ResultsFrom 1996 to 2009, SMRs in RA ranged from 13.0 (95% confidence interval [95% CI] 12.2, 13.9) to 9.2 deaths per 1,000 RA patients (95% CI 8.4, 10.0); and for those without RA from 8.7 (95% CI 8.6, 8.7) to 6.0 deaths (95% CI 5.9, 6.0) per 1,000 general population. Over the study period, the excess mortality rate among RA patients was approximately 3 excess deaths per 1,000 population. Relative reductions in standardized mortality rates occurred over time for those with and without RA (−21.4% versus −13.4%). The SMRs for RA patients in 1996–1997, 2000–2001, 2004–2005, and 2008–2009 were 1.51 (95% CI 1.43, 1.59), 1.50 (95% CI 1.43, 1.57), 1.43 (95% CI 1.37, 1.50), and 1.41 (95% CI 1.35, 1.47), respectively. We did not find a significant change in the MRR by calendar time.ConclusionMortality for RA patients has decreased over time but remains elevated compared to the general population, with 40–50% more deaths among RA patients. The relative excess mortality over time (mortality gap) remains unchanged in our sample.
Safety of Etoricoxib, Celecoxib, and Nonselective Nonsteroidal Antiinflammatory Drugs in Ankylosing Spondylitis and Other Spondyloarthritis Patients: A Swedish National Population‐Based Cohort Study
Authors: Kristensen L. E. , Jakobsen A. K. , Askling J. , Nilsson F. , Jacobsson L. T. H. 
Published: January 2015

ObjectiveSafety data regarding the use of etoricoxib and other nonsteroidal antiinflammatory drugs (NSAIDs) in ankylosing spondylitis (AS) and other spondyloarthritis (SpA) patients are rather limited. Our objective was to estimate and compare rates of gastrointestinal, renovascular, and cardiovascular adverse events in patients exposed to etoricoxib, celecoxib, or nonselective NSAIDs or totally unexposed to NSAIDs.MethodsWe performed a national register‐based cohort study on patients with AS or SpA (n = 21,872) identified in the Swedish national patient register from 1987–2009. Treatment exposure was assessed time dependently based on the prescription drug register from 2006–2009, adjusting for sociodemographics and comorbidities derived from national population‐based registers.ResultsExposure to etoricoxib, celecoxib, and nonselective NSAIDs was 7.6%, 3.9%, and 71.2%, respectively. No major risk differences for serious cardiovascular, gastrointestinal, or renal adverse events were seen among the 3 exposure groups. Patients unexposed to NSAIDs had more baseline comorbidities and an increased relative risk for congestive heart failure events during the study period (2.0, 95% confidence interval [95% CI] 1.3–3.2). The relative risk for atherosclerotic events was nonsignificant when compared to the nonselective NSAID group (1.0, 95% CI 0.7–1.5), while the relative risk for gastrointestinal events was lower for unexposed patients (0.5, 95% CI 0.4–0.7).ConclusionOverall, serious adverse events related to nonselective NSAIDs, etoricoxib, and celecoxib were similar and in the range of what would be expected in a group of SpA patients. Patients unexposed to NSAIDs had considerably more baseline comorbidities and increased risk for congestive heart failure, reflecting a selection of patients being prescribed NSAIDs in clinical practice.
Maintenance of Clinical and Radiographic Benefit With Intravenous Golimumab Therapy in Patients With Active Rheumatoid Arthritis Despite Methotrexate Therapy: Week‐112 Efficacy and Safety Results of the Open‐Label Long‐Term Extension of a Phase III, Double‐Blind, Randomized, Placebo‐Controlled Trial
Authors: Bingham Clifton O. , Mendelsohn Alan M. , Kim Lilianne , Xu Zhenhua , Leu Jocelyn , Han Chenglong , Lo Kim Hung , Westhovens Rene , Weinblatt Michael E. ,   on behalf of the GO‐FURTHER Investigators
Published: January 2015

ObjectiveTo evaluate the safety, efficacy, pharmacokinetics, immunogenicity, and radiographic progression through 2 years of treatment with intravenous (IV) golimumab plus methotrexate (MTX) in an open‐label extension of a phase III trial of patients with active rheumatoid arthritis (RA) despite MTX therapy.MethodsIn the phase III, double‐blind, randomized, placebo‐controlled GO‐FURTHER trial, 592 patients with active RA were randomized (2:1) to intravenous golimumab 2 mg/kg plus MTX (Group 1) or placebo plus MTX (Group 2) at weeks 0 and 4, then every 8 weeks thereafter; placebo patients crossed over to golimumab at week 16 (early escape) or week 24 (crossover). The final golimumab infusion was at week 100. Assessments included American College of Rheumatology 20%, 50%, 70% (ACR20, ACR50, ACR70) response criteria, 28‐joint count disease activity score using the C‐reactive protein level (DAS28‐CRP), physical function and quality of life measures, and changes in the modified Sharp/van der Heijde scores (SHS). Safety was monitored through week 112.ResultsIn total, 486 patients (82.1%) continued treatment through week 100, and 68.1%, 43.8%, and 23.5% had an ACR20/50/70 response, respectively, at week 100. Clinical response and improvements in physical function and quality of life were generally maintained from week 24 through 2 years. Mean change from baseline to week 100 in SHS score was 0.74 in Group 1 and 2.10 in Group 2 (P = 0.005); progression from week 52 to week 100 was clinically insignificant in both groups. A total of 481 patients completed the safety followup through week 112; 79.1% had an adverse event, and 18.2% had a serious adverse event.ConclusionClinical response to IV golimumab plus MTX was maintained through week 100. Radiographic progression following golimumab treatment was clinically insignificant between week 52 and week 100. No unexpected adverse events occurred through week 112, and the safety profile was consistent with anti–tumor necrosis factor therapy.
Efficiency Gains for Rheumatology Consultation Using a Novel Electronic Referral System in a Safety‐Net Health Setting
Authors: Scheibe Meghan M. , Imboden John B. , Schmajuk Gabriela , Margaretten Mary , Graf Jonathan D. , Chen Alice H. , Yelin Edward H. , Yazdany Jinoos 
Published: January 2015

ObjectiveHealth information technology (HIT) holds promise in increasing access to rheumatologists by improving the quality and efficiency of referrals, but few studies have examined its use for this purpose. We evaluated the use and impact of a novel electronic referral (eReferral) system in rheumatology in a safety‐net health system.MethodsWe examined eReferrals over 4 years. Our primary outcome was use of preconsultation exchange, defined as back‐and‐forth communication between referring and specialty care providers, facilitating triage of referrals, requests for more information, or resolution of questions without a visit. We calculated the proportion of eReferrals that underwent preconsultation exchange, time to reviewer response, and number of visits scheduled. To increase generalizability, we selected a random sample of eReferrals to undergo additional blinded, adjudicated review to assess agreement on appropriateness for preconsultation exchange.ResultsBetween 2008 and 2012, 2,383 eReferrals were reviewed and 2,105 were eligible for analysis. One‐fourth of eReferrals were resolved without a clinic visit. The proportion of eReferrals undergoing preconsultation exchange increased over time (55% in 2008 versus 74% in 2011), and the volume of referrals also steadily increased over time. Reviewer response time averaged between 1 and 4 days. In the random sample of eReferrals that underwent adjudicated review, agreement between reviewers was high (κ = 0.72).ConclusionHIT‐enabled preconsultation exchange was used for a majority of eReferrals and facilitated communication between referring clinicians and rheumatologists. This redesigned system of care allowed for triage of a high number of referrals, with many referrals determined to be appropriate for preconsultation exchange.
Fault diagnosis based on set membership identification using output‐error models
Authors: Reppa V. , Tzes A. 
Published: January 2015

SummaryThe objective of this article is the design of a fault diagnosis method based on set membership identification for systems subject to abrupt parametric faults. The proposed method assumes an output‐error, linearly parametrizable model, with unknown but bounded noise corrupting the measurement data. The set membership identification's objective is to compute (a) the smallest volume‐wise ellipsoid that contains the nominal parameter vector, which concurrently resides within a data‐hypersector and (b) the monotonically nonincreasing parametric set arisen from the orthotopes that tightly outer bound the ellipsoids. The fault detection mechanism is based on consistency tests between the estimated ellipsoids and the data‐hypersectors and the intersection of support orthotopes. At the sample instant of the fault detection, set‐theoretic operations are applied for the subsequent fault isolation and identification. The fault isolation is based on the projections of the intersections of orthotopes, while the distance of their centers is used for fault identification. Simulations studies are used to verify the efficiency of the suggested method applied on an electrostatic microactuator subject to several abrupt failure modes. Copyright © 2015 John Wiley & Sons, Ltd.
Fast and Complete Transimination of NH Imines into O‐Alkyl Oximes
Authors: Jeon Mina , Gupta Sreya , Im Young‐Woong , Rhee Young Ho , Park Jaiwook 
Published: January 2015

AbstractA synthetic method for making O‐alkyl oximes was developed by combining the Ru‐catalyzed transformation of alkyl azides into NH imines and a transimination reaction with O‐alkyl hydroxylamine hydrochlorides. This process provides a wide range of O‐alkyl oximes in high yields at room temperature in short reaction times.