bluuebunny/crossref_metadata_2025_split huggingface dataset:
Weekly cycles of global fires—Associations with religion, wealth and culture, and insights into anthropogenic influences on global climate
Authors: Earl Nick , Simmonds Ian , Tapper Nigel 
Published: November 2015

AbstractOne approach to quantifying anthropogenic influences on the environment and the consequences of those is to examine weekly cycles (WCs). No long‐term natural process occurs on a WC so any such signal can be considered anthropogenic. There is much ongoing scientific debate as to whether regional‐scale WCs exist above the statistical noise level, with most significant studies claiming that anthropogenic aerosols and their interaction with solar radiation and clouds (direct/indirect effect) is the controlling factor. A major source of anthropogenic aerosol, underrepresented in the literature, is active fire (AF) from anthropogenic burning for land clearance/management. WCs in AF have not been analyzed heretofore, and these can provide a mechanism for observed regional‐scale WCs in several meteorological variables. We show that WCs in AFs are highly pronounced for many parts of the world, strongly influenced by the working week and particularly the day(s) of rest, associated with religious practices.
A sporadic sodium layer event detected with five‐directional lidar and simultaneous wind, electron density, and electric field observation at Tromsø, Norway
Authors: Tsuda T. T. , Nozawa S. , Kawahara T. D. , Kawabata T. , Saito N. , Wada S. , Hall C. M. , Tsutsumi M. , Ogawa Y. , Oyama S. , Takahashi T. , Ejiri M. K. , Nishiyama T. , Nakamura T. , Brekke A. 
Published: November 2015

AbstractA sporadic sodium layer (SSL) was detected with five‐directional lidar observation on 15 December 2012 at Tromsø, Norway. We have derived the horizontal velocity of the SSL front from the SSL onset times at the five positions and compared it with the background wind velocity from the collocated meteor radar and European Incoherent Scatter (EISCAT) radar. As a result, both velocities were fairly consistent. The increase rate in the height‐integrated sodium density around the SSL onset was 3–6 ×1010 m−2 s−1, which was comparable to relatively large cases in the previous studies. However, the EISCAT‐observed electric field was too small to induce such a rapid sodium atom production. In addition, the amounts of the sodium atom increases at the five positions were mostly same. Thus, there were no clear signatures for the sodium atom production. These results strongly indicate that the observed SSL was just advected by the background wind.
Scaling of maximum observed magnitudes with geometrical and stress properties of strike‐slip faults
Authors: Martínez‐Garzón Patricia , Bohnhoff Marco , Ben‐Zion Yehuda , Dresen Georg 
Published: November 2015

AbstractWe test potential scaling between observed maximum earthquake magnitudes along 27 strike‐slip faults with various properties including cumulative displacement, mapped fault length, seismogenic thickness, slip rates, and angle between fault strike and maximum horizontal stress. For 75–80% of the data set, the observed maximum scalar moment scales with the product of seismogenic thickness and either cumulative displacement or mapped fault length. Most faults from this population have slip rates >5 mm/yr (interplate faults), cumulative displacement >10 km, and relatively high angles to the maximum horizontal stress orientation. The remaining 20–25% population involves events at some distance from a plate boundary with slip rate <5 mm/yr, cumulative displacements <10 km, and ≈ 45° to the maximum horizontal stress. These earthquakes have larger magnitudes than the previous population, likely because of larger stress drops. The most likely interpretation of the results is that the maximum rupture length, and hence earthquake magnitudes, correlates with the cumulative displacement and the fault surface length. The results also suggest that progressive fault smoothing may lead to decreasing coseismic stress drops.
Hall and finite Larmor radius effects on the dipolarization fronts associated with interchange instability
Authors: Lu H. Y. , Cao J. B. , Ge Y. S. , Zhang T. L. , Nakamura R. , Dunlop M. W. 
Published: November 2015

AbstractIn this paper, we established a Hall‐finite Larmor radius (FLR) MHD model by including Hall and finite Larmor radius (FLR) effects to study the dipolarization fronts (DFs) produced by the interchange instability in the magnetotail. The results indicate that the Hall effect on the scale of inertial length determines the distributions of electric field at DFs. The FLR effect can not only cause a dawn‐dusk asymmetry of the DF structure but also can make the DF drift dawnward. The dawnward drifting of DF can be attributed to the ion diamagnetic velocity, which also causes alteration in the direction of the high‐speed flow near the DF.
Elevated shear strength of sediments on active margins: Evidence for seismic strengthening
Authors: Sawyer Derek E. , DeVore Joshua R. 
Published: November 2015

AbstractEarthquakes are a primary trigger of submarine landslides, yet some of the most seismically active areas on Earth show a surprisingly low frequency of submarine landslides. Here we show that within the uppermost 100 m below seafloor (mbsf) in previously unfailed sediment, active margins have elevated shear strength by a factor of 2–3 relative to the same interval on passive margins. The elevated shear strength is seen in a global survey of undrained shear strength with depth as well as a normalized analysis that accounts for lithology and stress state. The enhanced shear strength is highest within the uppermost 10 mbsf. These results indicate that large areas of modern day slopes on active margins have enhanced slope stability, which may explain the relative paucity of landslides. These findings lend support to the seismic strengthening hypothesis that the repeated exposure to earthquake energy gradually increases shear strength by shear‐induced compaction.
Crustal seismic structure beneath the source area of the Columbia River flood basalt: Bifurcation of the Moho driven by lithosphere delamination
Authors: Gao Haiying 
Published: November 2015

AbstractThe source area of the ~16 Ma Columbia River flood basalt eruptions originated beneath the Wallowa Mountains in northeast Oregon, with a distinct circular pattern of topographic uplift. Teleseismic receiver functions reveal two layers between latitude 45.5° and 46.5° beneath north of the Wallowas, one at 25 km depth and the other one at 45 km depth. A new full‐wave ambient noise tomography model shows a circular anomaly, which is seismically fast in the upper crust and slow from lower crust to uppermost mantle in comparison with the surroundings, coincident with the circular pattern of the Wallowas. The seismic structures suggest that delamination of the Farallon lithosphere initiated the basalt eruptions and, consequently, modified the lowermost crust, forming a new shallow Moho. The Farallon slab is probably detached directly beneath the Wallowas while being maintained at the northern edge of the Wallowas, corresponding to the deeper interface.
A definition for rapid weakening of North Atlantic and eastern North Pacific tropical cyclones
Authors: Wood Kimberly M. , Ritchie Elizabeth A. 
Published: November 2015

AbstractPeriods of 24 h over‐water weakening during 1982–2013 for North Atlantic (NAL) and eastern North Pacific (ENP) tropical cyclones (TCs) are examined to determine a threshold for rapid weakening (RW). These periods are defined by consistent weakening while the TC center remained more than 50 km from land. Weakening thresholds of 25, 30, and 35 kt represent the 87th (69th), 94th (80th), and 97th (89th) percentile in the NAL (ENP). Based on these statistics, the 30 kt threshold is chosen to define RW. Compared to all weakening periods, RW events are generally associated with greater 24 h official forecast errors, and these errors tend to be overestimates in both basins. These events usually occur as the TC crosses a sharp sea surface temperature gradient, encounters greater vertical wind shear, and entrains drier air. These metrics may be useful to forecasters assessing the likelihood of RW.
An analytical model for relating global terrestrial carbon assimilation with climate and surface conditions using a rate limitation framework
Authors: Yang Yuting , Donohue Randall J. , McVicar Tim R. , Roderick Michael L. 
Published: November 2015

AbstractWe develop an analytical model for estimating mean annual terrestrial gross primary productivity (GPP) based on a rate limitation framework. Actual GPP (climatological mean from 1982 to 2010) is calculated as a function of the balance between two GPP potentials defined by the climate (i.e., precipitation and solar radiation) and a third parameter that encodes other environmental variables and modifies the GPP‐climate relationship. The model was tested using observed GPP from 94 flux sites and modeled GPP (using the model tree ensemble approach) at 48,654 (0.5°) grid cells globally. Results show that the model could account for the spatial GPP patterns, with a root‐mean‐square error of 0.70 and 0.65 g C m−2 d−1 and R2 of 0.79 and 0.92 for the flux site and grid cell scales, respectively. This analytical GPP model shares a similar form with the Budyko hydroclimatological model, which opens the possibility of a general analytical framework to analyze the linked carbon‐water‐energy cycles.
Peculiarities of magnetic barrier formation for southward and northward directions of the IMF
Authors: Slivka K. Yu. , Semenov V. S. , Erkaev N. V. , Dmitrieva N. P. , Kubyshkin I. V. , Lammer H. 
Published: November 2015

AbstractThe magnetic barrier is a region which is formed in the course of the solar wind flow around the Earth's magnetosphere and is characterized by depleted plasma and an enhanced magnitude of the magnetic field. There is a general point of view that the magnetic barrier can persist only for the northward interplanetary magnetic field (IMF), whereas it is practically absent if the IMF is southward directed. We studied the presence of the magnetic barrier for low‐shear (predominantly northward IMF) and high‐shear (predominantly southward IMF) magnetopause conditions and analyzed 74 events of low‐latitude dayside magnetopause crossings by the Time History of Events and Macroscale Interactions during Substorms satellites. We used the superposed epoch analysis to study variations of magnetic field and plasma parameters near the magnetopause. Results of Phan et al. (1994) that the magnetic barrier is well pronounced for low‐shear magnetopauses and practically absent for high‐shear events have been confirmed by our analysis. However, 5 from 49 high‐shear events show clear signatures of a magnetic barrier. Hence, we conclude that the magnetic barrier is formed in the same manner for all direction of IMF but for high‐shear events it is destroyed by reconnection much faster than it accumulates. Ratio of the events with and without magnetic barrier signatures (5/44) is approximately equal to the ratio of characteristic times of disruption due to reconnection (1–2 min) and the formation of a magnetic barrier (10 min). The reduction of the magnetic field due to reconnection can be used to estimate reconnection rate which turns out to be rather high of the order of 0.3 in 19 from 31 cases.
Statistical study of midlatitude E region echoes observed by the Hokkaido SuperDARN HF radar
Authors: Yakymenko K. N. , Koustov A. V. , Nishitani N. 
Published: November 2015

AbstractStatistical characteristics of short‐range coherent echoes observed by the Hokkaido Super Dual Auroral Radar Network (SuperDARN) high‐frequency (HF) radar (geographic/geomagnetic latitude = 43.5°N/37.3°N) at midlatitudes are investigated. We show that the echo occurrence is increased during nighttime and, especially strongly, during winter and summer. During summer, the occurrence rates are still large during morning‐prenoon hours; for these periods, strong sporadic E layers are observed by the Wakkanai ionosonde (geographic/geomagnetic latitude = 45.2°N/39.1°N) located in the vicinity of the radar field of view. Echo occurrence rate does not increase with the planetary magnetic activity characterized by the Kp and Dst magnetic indices and, seasonally, anticorrelates with variations of the Ap index. With respect to the magnetic L shells, echoes are seen more frequently in beams oriented almost perpendicular to L shells during summer, in beams at intermediate angles during equinoxes and winter, and sometimes in beams at the smallest available angles (~45°) during winter. Midlatitude echoes are of about the same power as at high latitudes but narrower by a factor of ~5. Power and spectral width of nighttime echoes increases with Doppler velocity, consistent with high‐latitude observations. The Doppler velocity shows a clear semidiurnal variation. The local time of these maxima changes with season. It is hypothesised that many Hokkaido echoes are received at high magnetic aspect angles of several degrees, and they are coming from the lower part of the E region where the irregularity phase velocity is affected by both E × B plasma drifts and neutral winds.
Age‐dependent forest carbon sink: Estimation via inverse modeling
Authors: Zhou Tao , Shi Peijun , Jia Gensuo , Dai Yongjiu , Zhao Xiang , Shangguan Wei , Du Ling , Wu Hao , Luo Yiqi 
Published: November 2015

AbstractForests have been recognized to sequester a substantial amount of carbon (C) from the atmosphere. However, considerable uncertainty remains regarding the magnitude and time course of the C sink. Revealing the intrinsic relationship between forest age and C sink is crucial for reducing uncertainties in prediction of forest C sink potential. In this study, we developed a stepwise data assimilation approach to combine a process‐based Terrestrial ECOsystem Regional model, observations from multiple sources, and stochastic sampling to inversely estimate carbon cycle parameters including carbon sink at different forest ages for evergreen needle‐leaved forests in China. The new approach is effective to estimate age‐dependent parameter of maximal light‐use efficiency (R2 = 0.99) and, accordingly, can quantify a relationship between forest age and the vegetation and soil C sinks. The estimated ecosystem C sink increases rapidly with age, peaks at 0.451 kg C m−2 yr−1 at age 22 years (ranging from 0.421 to 0.465 kg C m−2 yr−1), and gradually decreases thereafter. The dynamic patterns of C sinks in vegetation and soil are significantly different. C sink in vegetation first increases rapidly with age and then decreases. C sink in soil, however, increases continuously with age; it acts as a C source when the age is less than 20 years, after which it acts as a sink. For the evergreen needle‐leaved forest, the highest C sink efficiency (i.e., C sink per unit net primary productivity) is approximately 60%, with age between 11 and 43 years. Overall, the inverse estimation of carbon cycle parameters can make reasonable estimates of age‐dependent C sequestration in forests.
Impact of Treatment With Biologic Agents on the Use of Mechanical Devices Among Rheumatoid Arthritis Patients in a Large US Patient Registry
Authors: Strand Vibeke , Greenberg Jeffrey D. , Griffith Jenny , Bao Yanjun , Saunders Katherine C. , Garg Vishvas , Li Guo , Ganguli Arijit 
Published: November 2015

ObjectiveTo assess trends and predictors of mechanical devices/aids use by rheumatoid arthritis (RA) patients since the introduction of biologic disease‐modifying antirheumatic drugs (DMARDs).MethodsSociodemographic characteristics, disease characteristics, and mechanical aid use (assessed using the Health Assessment Questionnaire) were compared among RA patients ages >17 years at diagnosis, enrolled in the Consortium of Rheumatology Researchers of North America (CORRONA) registry during January 2001 to December 2003 and January 2010 to December 2012. Univariate and multivariate logistic regression analyses were used to identify predictors of mechanical aid use among patients in both cohorts.ResultsSociodemographic characteristics were similar between 1,096 patients in the 2001–2003 cohort and 11,140 patients in the 2010–2012 cohort. Disease activity was significantly lower among patients in the 2010–2012 cohort (mean ± SD Clinical Disease Activity Index score 10.1 ± 11.1 versus 17.0 ± 13.8; P < 0.001). A greater proportion of patients in the 2010–2012 cohort received biologic DMARDs (50.7% versus 32.5%; P < 0.001) and fewer were biologic‐naive (39.1% versus 61.6%; P < 0.001). Fewer patients in the 2010–2012 cohort used any mechanical devices/aids (31.1% versus 40.8%; P < 0.001). In multivariate analysis, patients in the 2010–2012 cohort and those with a history of biologic agent use were less likely to use devices/aids (odds ratio [OR] 0.77 [95% confidence interval (95% CI) 0.66–0.90] and OR 0.68 [95% CI 0.62–0.75], respectively). Predictors of greater devices/aids usage included older age, female sex, higher disease activity, and less employment. Effect sizes were greatest for disease activity and employment.ConclusionMechanical devices/aids use among patients with RA was significantly lower during 2010–2012 versus 2001–2003 and among biologic‐experienced patients, suggesting reduced disability.
Predictors of Fatigue in Rheumatoid Arthritis Patients in Remission or in a Low Disease Activity State
Authors: Olsen Christin L. , Lie Elisabeth , Kvien Tore K. , Zangi Heidi A. 
Published: November 2015

ObjectiveFatigue is a frequently occurring symptom in patients with rheumatoid arthritis (RA). Our aims were to assess the level of reported fatigue in RA patients who had achieved remission or low disease activity after 6 months of treatment with disease‐modifying antirheumatic drugs (DMARDs), and to explore associations between fatigue and demographics, disease activity, and other patient‐reported outcomes in this patient group.MethodsA total of 2,193 RA patients (ages ≥18 years) starting either methotrexate (MTX) monotherapy or a tumor necrosis factor inhibitor in combination with MTX were retrieved from the Norwegian Disease‐Modifying Antirheumatic Drugs Register (NOR‐DMARD). At the 6‐month followup, 699 patients (31.9%) were in remission or in a low disease activity state. Bivariate and multivariate linear regression analyses were conducted, with the fatigue visual analog scale (VAS) at 6 months as the dependent variable. Age, sex, disease duration, treatment group, erythrocyte sedimentation rate (ESR), the swollen and tender joint count in 28 joints, the pain VAS score, and disability at baseline and at 6 months were tested as predictors of fatigue at 6 months.ResultsAt 6 months, the median (25th, 75th percentile) level of fatigue was 20.0 mm (6.0, 43.0), and a fatigue VAS score of ≥40 mm was reported by 27.9% of patients. In the multivariate analysis, lower ESR and higher pain at baseline were statistically significant predictors of higher levels of fatigue (P < 0.001). In the multivariate cross‐sectional analysis at 6 months, younger age and greater pain were significantly associated with higher levels of fatigue (P < 0.001).ConclusionPain levels at baseline and at 6 months were associated with a higher level of fatigue. Patients in remission or in a low disease activity state may need nonpharmacologic interventions to manage their pain and fatigue.
Robust adaptive iterative learning control for discrete‐time nonlinear systems with both parametric and nonparametric uncertainties
Authors: Yu Miao , Huang Deqing , He Wei 
Published: November 2015

SummaryA new robust adaptive iterative learning control approach is proposed for discrete‐time nonlinear systems with both parametric and nonparametric uncertainties. By virtue of a well‐designed dead‐zone function, the learning of the parametric and nonparametric uncertainties can be performed concurrently. Rigorous Lyapunov function‐based analysis ensures that the effect of system uncertainties can be fully compensated, and the tracking error will converge to zero asymptotically in the iteration domain, even under random initial conditions and iteration‐varying reference trajectories. The efficacy of the proposed controller is demonstrated by simulating a single‐link robot manipulator with unknown frictions. Copyright © 2015 John Wiley & Sons, Ltd.
Struktur der Dioxygenase AsqJ: mechanistische Einblicke in die Eintopf‐Mehrstufen‐Biosynthese eines Chinolonantibiotikums
Authors: Bräuer Alois , Beck Philipp , Hintermann Lukas , Groll Michael 
Published: November 2015

AbstractFür die Biosynthese von Naturstoffen sind Multi‐Enzymkaskaden verantwortlich, die generell eine Inspirationsquelle für Synthesechemiker darstellen. Die FeII/α‐Ketoglutarat‐abhängige Dioxygenase AsqJ aus Aspergillus nidulans ist außergewöhnlich, da sie stereoselektiv sowohl eine Desaturierung als auch Epoxidierung eines Benzodiazepindions katalysiert. Interessanterweise löst das enzymatisch gebildete, gespannte Spiro‐Epoxid die enzymunabhängige Umlagerung des 6,7‐Bicyclus zum 6,6‐Chinolongerüst des Alkaloids 4′‐Methoxyviridicatin aus. Verschiedene Kristallstrukturen des Proteins in Ab‐ und Anwesenheit synthetisierter Substrate, Substratanaloga und Zwischenprodukte erlaubten uns, die einzelnen Stufen der Reaktionssequenz dieser einzigartigen Dioxygenase nachzuahmen und zu hinterleuchten.
Precrystalline Aggregates Enable Control over Organic Crystallization in Solution
Authors: Shahar Chen , Dutta Sounak , Weissman Haim , Shimon Linda J. W. , Ott Holger , Rybtchinski Boris 
Published: November 2015

AbstractUnderstanding and controlling organic crystallization in solution is a long‐standing challenge. Herein, we show that crystallization of an aromatic amphiphile based on perylene diimide in aqueous media involves initially formed amorphous spherical aggregates that evolve into the crystalline phase. The initial appearance of the crystalline order is always confined to the spherical aggregates that are precursors for crystalline evolution. The change in the solvation of the prenucleation phase drives the crystallization process towards crystals that exhibit very different structure and photofunction. The initial molecular structure and subsequent crystal evolution can be regulated by tuning the hydrophobicity at various stages of crystallization, affording dissimilar crystalline products or hindering crystallization. Thus, the key role of the precrystalline states in organic crystal evolution enables a new strategy to control crystallization by precrystalline state manipulation.
A Highly Reactive Seven‐Coordinate Osmium(V) Oxo Complex: [OsV(O)(qpy)(pic)Cl]2+
Authors: Liu Yingying , Ng Siu‐Mui , Lam William W. Y. , Yiu Shek‐Man , Lau Tai‐Chu 
Published: November 2015

AbstractSeven‐coordinate ruthenium oxo species have been proposed as active intermediates in catalytic water oxidation by a number of highly active ruthenium catalysts, however such species have yet to be isolated. Reported herein is the first example of a seven‐coordinate group 8 metal‐oxo species, [OsV(O)(qpy)(pic)Cl]2+ (qpy=2,2′:6′,2′′:6′′,2′′′‐quaterpyridine, pic=4‐picoline). The X‐ray crystal structure of this complex shows that it has a distorted pentagonal bipyramidal geometry with an OsO distance of 1.7375 Å. This oxo species undergoes facile O‐atom and H‐atom‐transfer reactions with various organic substrates. Notably it can abstract H atoms from alkylaromatics with CH bond dissociation energy as high as 90 kcal mol−1. This work suggests that highly active oxidants may be designed based on group 8 seven‐coordinate metal oxo species.
Radical [1,3] Rearrangements of Breslow Intermediates
Authors: Alwarsh Sefat , Xu Yi , Qian Steven Y. , McIntosh Matthias C. 
Published: November 2015

AbstractBreslow intermediates that bear radical‐stabilizing N substituents, such as benzyl, cinnamyl, and diarylmethyl, undergo facile homolytic CN bond scission under mild conditions to give products of formal [1,3] rearrangement rather than benzoin condensation. EPR experiments and computational analysis support a radical‐based mechanism. Implications for thiamine‐based enzymes are discussed.