bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for Slip on a Border Fault Triggered by Magmatic Processes in an Immature Continental Rift
Authors: Jones J. Robert , Stamps D. Sarah , Wauthier Christelle , Saria Elifuraha , Biggs Juliet 
Published: March 2019

AbstractContinental rifting evolves through repeated tectonic and magmatic processes. Here we investigate the 2007–2008 northern Tanzania rifting episode to understand the interactions between magmatism and border fault slip during immature continental rifting. We compare modeled stress changes with geodetic observations from the western adjacent border fault of the Natron basin. We model six distinct phases of the rifting episode, including the eruptive activity of Ol Doinyo Lengai. The southern portion of the border fault experienced a positive cumulative Coulomb stress change, consistent with newly processed Global Positioning System data showing a distinct instance of slip during this time period. Our work suggests active volcanism and faulting are correlated in time, indicating magmatism associated with volcanic activity influences slip on border faults in immature continental rifts.
EMIC Wave‐Driven Bounce Resonance Scattering of Energetic Electrons in the Inner Magnetosphere
Authors: Blum L.W. , Artemyev A. , Agapitov O. , Mourenas D. , Boardsen S. , Schiller Q. 
Published: March 2019

AbstractWhile electromagnetic ion cyclotron (EMIC) waves have been long studied as a scattering mechanism for ultrarelativistic (megaelectron volt) electrons via cyclotron‐resonant interactions, these waves are also of the right frequency to resonate with the bounce motion of lower‐energy (approximately tens to hundreds of kiloelectron volts) electrons. Here we investigate the effectiveness of this bounce resonance interaction to better determine the effects of EMIC waves on subrelativistic electron populations in Earth's inner magnetosphere. Using wave and plasma parameters directly measured by the Van Allen Probes, we estimate bounce resonance diffusion coefficients for four different events, illustrative of wave and plasma parameters to be encountered in the inner magnetosphere. The range of electron energies and pitch angles affected is examined to better assess the realistic effects of EMIC‐driven bounce resonance on energetic electron populations based on actual, locally observed event‐based parameters. Significant local diffusion coefficients (~ > 10−6 s−1) for 50‐ to 100‐keV electrons are achieved for both H+ band wave events as well as He+ band, with diffusion coefficients peaking for near‐90° pitch angles but remaining elevated for intermediate ones as well. Diffusion coefficients for higher‐energy 200‐keV electrons are typically multiple orders of magnitude lower (ranging from 10−11 to 10−6 s−1) and often peak at lower pitch angles (~20–30°). These results suggest that both H+ and He+ band EMIC waves can play a role in shaping lower‐energy electron dynamics via bounce‐resonant interactions, in addition to their role in relativistic electron loss via cyclotron resonance.
Preferential Orthopyroxene Serpentinization and Implications for Seismic Velocity Interpretation in the Fore‐Arc Mantle
Authors: Nakatani T. , Nakamura M. 
Published: March 2019

AbstractFor better interpretation of seismic tomography data of the hydrated fore‐arc mantle, we examined conditions of nonstoichiometric hydration of peridotite reported by a previous experimental study (i.e., preferential orthopyroxene (Opx) serpentinization and resultant talc formation) at 500–580 °C and under 0.8–1.8 GPa. The corresponding seismic velocity was calculated by considering the talc production. Talc formed under all the experimental conditions even in the olivine‐dominated system, in which the olivine to Opx ratio was 7:3 by weight. The amount of talc produced was comparable to that of serpentine at high temperature and low pressure and increased with increasing temperature and decreasing pressure due to decreasing contribution of olivine in the reaction. We also present a natural case of preferential Opx reaction in the Horoman peridotite complex, Japan, on the basis of its strong similarity in textures and mineral phases to our experimental products obtained at 0.8–1.3 GPa. Calculations on seismic velocities of hydrated harzburgite using the Voigt‐Reuss‐Hill averaging scheme showed that the formation of talc along with antigorite leads to a decrease in P wave (Vp) and S wave velocities (Vs) but no remarkable increase in Vp/Vs due to the lower Vp/Vs value of talc (~1.60) compared with that of antigorite (~1.77). Such a seismic anomaly has been observed in the shallow mantle wedge of the southern Western Alps subduction zone, where suppressed water supply from the subducted continental lithosphere might allow the persistence of talc produced by the preferential Opx reaction.
Sea Surface Salinity Distribution in the Southern Ocean as Observed From Space
Authors: Garcia‐Eidell Cynthia , Comiso Josefino C. , Dinnat Emmanuel , Brucker Ludovic 
Published: March 2019

AbstractLarge‐scale spatial and temporal variabilities of sea surface salinity (SSS) in the Southern Ocean from 2011 to 2017 were studied using products derived from microwave sensors on board Aquarius, Soil Moisture and Ocean Salinity (SMOS), and Soil Moisture Active and Passive (SMAP) satellites. Four products, three from Aquarius and one from SMOS, were evaluated and shown to be generally consistent within 0.3 to 0.6 psu and agree favorably with in situ measurements. However, although the Aquarius products show consistent seasonality of SSS with high values of 34.45 psu in October and low values of 33.40 psu in May, the SMOS and SMAP products lack such seasonal variations. This may be caused by larger uncertainties in the SMOS and SMAP data due in part to the lack of concurrent scatterometer measurements that is used to correct for roughness effects. The four products provide similar spatial distributions of SSS with root‐mean‐square difference from 0.25 to 0.58 psu. Differences among Aquarius products are mainly due to varying salinity retrieval algorithms, smoothing, and masking of sea ice, while the SMOS product showed the highest SSS deviation that is likely due to the bias‐adjustment done on the data set. Our analyses show that SSS in the Southern Ocean region has significant meridional variations with the lowest SSS near the ice edge and highest at lower latitudes. The SSS is also lowest in summer indicating the predominant influence of sea ice and glacial melt, but it stays low near ice edges even during the growth season.
A Comparison of the Atlantic and Pacific Bjerknes Feedbacks: Seasonality, Symmetry, and Stationarity
Authors: Dippe T. , Lübbecke J. F. , Greatbatch R. J. 
Published: March 2019

AbstractThe Bjerknes feedback is the dominant positive feedback in the equatorial ocean basins. To examine the seasonality, symmetry, and stationarity of the Pacific and Atlantic Bjerknes feedbacks we decompose them into three feedback elements that relate thermocline depth, sea surface temperature, and western basin wind stress variability to each other. We partition feedback elements into composites associated with positive or negative anomalies. Using robust regression, we diagnose the strength of each composite. For the recent period 1993–2012, composites of the Pacific Bjerknes feedback elements agree well with previous work. Positive composites are generally stronger than negative composites, and all feedback elements are weakest in late boreal spring. In the Atlantic, differences between positive and negative composites are less consistent across feedback elements. Specifically, wind variability seems to play a less important role in shaping atmosphere‐ocean coupling in the Atlantic when compared to the Pacific. However, a clear seasonality emerges: Feedback elements are generally strong in boreal summer and, for the negative composites, again in boreal winter. The Atlantic Bjerknes feedback is dominated by subsurface‐surface coupling. Applying our analysis to overlapping 25‐year periods for 1958–2009 shows that the strengths of feedback elements in both ocean basins vary on decadal time scales. While the overall asymmetry of the Pacific Bjerknes feedback is robust, the strength and symmetry of Atlantic feedback elements vary considerably between decades. Our results indicate that the Atlantic Bjerknes feedback is nonstationary on decadal time scales.
Plant Feedback Aggravates Soil Organic Carbon Loss Associated With Wind Erosion in Northwest China
Authors: Lei Lingjie , Zhang Kesheng , Zhang Xuanze , Wang Ying‐Ping , Xia Jianyang , Piao Shilong , Hui Dafeng , Zhong Mingxing , Ru Jingyi , Zhou Zhenxing , Song Hongquan , Yang Zhongling , Wang Dong , Miao Yuan , Yang Fan , Liu Bin , Zhang Ang , Yu Mengyang , Liu Xianghui , Song Yongheng , Zhu Lili , Wan Shiqiang 
Published: March 2019

AbstractSoil organic carbon (SOC) loss caused by wind erosion can profoundly impact carbon (C) balance in arid and semiarid regions. Nevertheless, previous researches mainly focused on the direct effect of wind erosion through removing surface soil only but ignored its indirect effects associated with soil nitrogen (N) loss and subsequent reductions of plant productivity. To better understand the wind erosion effect on SOC storage, we conducted a large‐scale field experiment by manipulating wind erosion at 371 sites in arid and semiarid regions of northwest China from 2014 to 2016. We further integrated an observation‐based empirical equation of wind erosion process into a terrestrial biogeochemical model to evaluate the direct and indirect effects of wind erosion on SOC storage in northwest China. The observed results showed that direct SOC losses increased linearly with the square of wind speed but decreased nonlinearly with soil water content. Over the 34 years (1980–2013), simulated cumulative SOC losses associated with wind erosion in northwest China were 27.47 Tg C, among which the indirect effects contributed to 2.68 Tg C (9.76%). The indirect effect of wind erosion initially enhanced SOC storage by decreasing heterotrophic respiration from 1984 to 1988 but decreased SOC pool by reducing net primary productivity due to soil N loss under the long‐term wind erosion scenario. This work, for the first time, quantified the indirect impact of wind erosion on SOC storage via feedback of suppressed plant productivity, which is crucial for the convincing assessment on SOC storage in arid and semiarid regions.
Aerosol‐Cloud‐Precipitation Interactions in the Context of Convective Self‐Aggregation
Authors: Beydoun H. , Hoose C. 
Published: March 2019

AbstractWe investigate the sensitivity of self‐aggregated radiative‐convective‐equilibrium cloud‐resolving model simulations to the cloud condensation nuclei (CCN) concentration. Experiments were conducted on a long (2,000‐km × 120‐km) channel domain, allowing the emergence of multiple convective clusters and dry regions of subsidence. Increasing the CCN concentration leads to increased moisture in the dry regions, increased midlevel and upper level clouds, decreased radiative cooling, and decreased precipitation. We find that these trends follow from a decrease in the strength of the self‐aggregation as measured by the moist static energy (MSE) variance. In our simulations, precipitation is correlated, both locally and in total, with the distribution of MSE anomalies. We thus quantify changes in the adiabatic/diabatic contributions to MSE anomalies (Wing & Emanuel, 2014, https://doi.org/10.1002/2013MS000269) and relate those changes to changes in precipitation. Through a simple two‐column conceptual model, we argue that the reduction in precipitation can be explained thermodynamically by the reduction in mean net radiative cooling and mechanistically by the weakening of the area‐weighted radiatively driven subsidence velocity—defined as the ratio of the total radiative cooling over the dry regions and the static stability. We interpret the system's response to increasing CCN as a thermodynamically constrained realization of an aerosol indirect effect on clouds and precipitation.
Thermotectonic Evolution of the North Pyrenean Agly Massif During Early Cretaceous Hyperextension Using Multi‐mineral U‐Pb Thermochronometry
Authors: Odlum M. L. , Stockli D. F. 
Published: March 2019

AbstractThe North Pyrenean Zone represents a fossil hyperextended passive margin, with limited orogenic overprinting, where the thermal and structural patterns associated with crustal thinning and mantle exhumation can be studied on rocks exposed at the surface. The Agly Massif is a tilted ~10‐km‐thick crustal section of Paleozoic and upper Proterozoic magmatic and greenschist to granulitic metamorphic rocks in the easternmost North Pyrenean Zone. We applied multi‐mineral geochronometry and thermochronometry on structural/crustal transects across the massif to understand the exhumation history of the upper and lower continental crust during extreme crustal thinning and mantle exhumation. Integration of zircon and apatite U‐Pb ages provides unprecedented constraints to understand the decoupled versus coupled extensional evolution, exhumation timing of the middle‐lower crust, and the age of juxtaposition of the upper crust granitic pluton with high‐grade gneisses. The Saint Arnac pluton was emplaced and cooled in the upper crust during the Carboniferous and remained at temperatures between 450 and 180 °C until the Late Cretaceous. The middle to lower crust was metamorphosed during the Carboniferous and remained at temperatures >450 °C until the Aptian, when it was rapidly exhumed along a midcrustal shear zone. Deformation was initially decoupled along a midcrustal ductile shear zone until the whole massif was in the brittle field, with structural juxtaposition of the units, and exhumation was coupled and controlled by a major southward dipping detachment fault at the southern border of the massif. The basement massif and synrift sedimentary rocks record significantly different thermal histories during rifting.
Climatic Controls on Landscape Dissection and Network Structure in the Absence of Vegetation
Authors: Hooshyar Milad , Singh Arvind , Wang Dingbao , Foufoula‐Georgiou Efi 
Published: March 2019

AbstractDrainage networks emerge due to the movement of sediment driven by climatic and tectonic forcings. Previous observations revealed the dependence of drainage density (Dd) on climatic factors such as mean annual precipitation (MAP). Specifically, it has been observed in intermediate climate (~175 mm < MAP < 700 mm) that Dd decreases with increasing MAP. This declining trend has been argued to be attributed to biotic activity, that is, the dominance of vegetation growth over runoff erosive force. Using high‐resolution topographic data from a physical experiment, we show that increasing rainfall may result in decreasing Dd even in the absence of biotic activity. Increasing rainfall rate results in narrower and less variable bifurcation angle and relatively longer links. The response of the evolving network in terms of bifurcation angle continues beyond the time when Dd has reached a new stable value, indicating that the network's topological response is relatively slower than the geomorphic response.
Prediction of Reservoir Storage Anomalies in India
Authors: Tiwari Amar Deep , Mishra Vimal 
Published: March 2019

AbstractReservoirs provide water for irrigation and hydropower and protect downstream regions from flooding. Reservoir storage is affected by drought, which hampers the ability to provide water for irrigation and hydropower. Despite the need for reservoir storage prediction for planning and decision‐making, a reservoir storage forecast system at 1‐ to 3‐month lead has been lacking for major reservoirs in India. Here we evaluate the potential of observed accumulated precipitation, standardized precipitation index (SPI), standardized precipitation evapotranspiration index (SPEI), standardized streamflow index (SSI), and observed reservoir storage to provide reservoir storage anomaly forecast at 1‐ to 3‐month lead for the dry season (February to May) using a statistical approach. We find that accumulated precipitation for 3–11 months is strongly associated with the monthly reservoir storage anomalies in India. Moreover, accumulated precipitation and observed reservoir storage provide a reasonable (R2 = 0.7) forecast skill for reservoir storage anomalies at 1‐ to 3‐month lead. Similarly, SPI and SPEI can be used to predict reservoir storage anomalies at 1‐ to 3‐month lead in India. Since the prediction skill from SPI and SPEI is similar, reservoir storage at monthly timescale is largely affected by accumulated precipitation instead of variability in air temperature. We find that the forecast skill for the 1‐month lead from SPI, SPEI, and SSI is similar for Indira Sagar (Narmada) and Minimata (Mahanadi) reservoirs; however, prediction skill for reservoir storage anomalies improves substantially using SSI for 2‐ to 3‐month lead. Reservoir storage anomalies forecast at 1‐to 3‐month lead can be valuable for water management‐related decision‐making and planning during the dry season in India.
Net Ecosystem Carbon Balance of a Peat Bog Undergoing Restoration: Integrating CO2 and CH4 Fluxes From Eddy Covariance and Aquatic Evasion With DOC Drainage Fluxes
Authors: D′Acunha Brenda , Morillas Laura , Black T. Andrew , Christen Andreas , Johnson Mark S. 
Published: March 2019

AbstractPeatland ecosystems are generally carbon (C) sinks. However, the role of dissolved organic C (DOC) relative to gaseous fluxes of CO2 and CH4 in the C balance of these ecosystems has not often been studied. Dissolved C fluxes are important for understanding C partitioning within the peatland and the potential C drainage from it. This research was conducted in Burns Bog, a heavily impacted ecosystem near Vancouver, Canada, undergoing ecological restoration efforts by rewetting. Here we present data on (i) ecosystem‐scale fluxes of CO2 (net ecosystem exchange, NEE) and CH4 (FCH4) determined by eddy covariance, (ii) evasion fluxes of CO2 and CH4 from the water surface to estimate the role of open water in ecosystem‐scale fluxes, and (iii) DOC flux (fDOC) in water draining from the peatland. Our results showed that open water areas inside the footprint were a continual C source, emitting 47.0 ± 2.4 g C·m−2·year−1. DOC export (15.6 g C·m−2·year−1) was significant to the net ecosystem C balance, decreasing the magnitude of the eddy covariance‐determined C balance (i.e., NEE + FCH4) of −45.0 ± 16.8 g C·m−2·year−1 by 35%, resulting in a net ecosystem C balance (i.e., NEE + FCH4 + fDOC) of −29.7 ± 17.0 g C·m−2·year−1. Most of this offset occurred during the wetter nongrowing season when gross primary production was low and fDOC was relatively high.
Shared mechanisms between coronary heart disease and depression: findings from a large UK general population-based cohort
Authors: Khandaker Golam M. , Zuber Verena , Rees Jessica M. B. , Carvalho Livia , Mason Amy M. , Foley Christopher N. , Gkatzionis Apostolos , Jones Peter B. , Burgess Stephen 
Published: March 2019

AbstractWhile comorbidity between coronary heart disease (CHD) and depression is evident, it is unclear whether the two diseases have shared underlying mechanisms. We performed a range of analyses in 367,703 unrelated middle-aged participants of European ancestry from UK Biobank, a population-based cohort study, to assess whether comorbidity is primarily due to genetic or environmental factors, and to test whether cardiovascular risk factors and CHD are likely to be causally related to depression using Mendelian randomization. We showed family history of heart disease was associated with a 20% increase in depression risk (95% confidence interval [CI] 16–24%, p < 0.0001), but a genetic risk score that is strongly associated with CHD risk was not associated with depression. An increase of 1 standard deviation in the CHD genetic risk score was associated with 71% higher CHD risk, but 1% higher depression risk (95% CI 0–3%; p = 0.11). Mendelian randomization analyses suggested that triglycerides, interleukin-6 (IL-6), and C-reactive protein (CRP) are likely causal risk factors for depression. The odds ratio for depression per standard deviation increase in genetically-predicted triglycerides was 1.18 (95% CI 1.09–1.27; p = 2 × 10−5); per unit increase in genetically-predicted log-transformed IL-6 was 1.35 (95% CI 1.12–1.62; p = 0.0012); and per unit increase in genetically-predicted log-transformed CRP was 1.18 (95% CI 1.07–1.29; p = 0.0009). Our analyses suggest that comorbidity between depression and CHD arises largely from shared environmental factors. IL-6, CRP and triglycerides are likely to be causally linked with depression, so could be targets for treatment and prevention of depression.
Pharmacologic or genetic activation of SIRT1 attenuates the fat-induced decrease in beta-cell function in vivo
Authors: Desai Tejas , Koulajian Khajag , Ivovic Aleksandar , Breen Danna M. , Luu Lemieux , Tsiani Evangelia L. , Wheeler Michael B. , Giacca Adria 
Published: March 2019

Abstract
Background
There is evidence that sirtuin 1 (SIRT1), a key regulator of nutrient metabolism, increases β-cell secretory function. Excess circulating fat, as seen in obesity, has been shown to decrease β-cell function, an effect that may involve decreased SIRT1 activity. Consequently, SIRT1 activation may increase β-cell function in conditions of elevated plasma-free fatty acid levels. Here we attempted to attenuate the lipid-induced decrease in β-cell function in vivo using pharmacological and genetic models of SIRT1 activation.

Methods
Our pharmacologic model involved 48 h intravenous infusion of Wistar rats with either saline or oleate with or without the SIRT1 activator resveratrol. Additionally, we used β-cell-specific SIRT1 overexpressing (BESTO) mice and wild-type littermates infused for 48 h intravenously with either saline or oleate. In both models, the infusion period was followed by assessment of β-cell function using the hyperglycemic clamp method.

Results
Lipid infusion resulted in a significant decrease in β-cell function as expected in both rats (p < 0.05) and mice (p < 0.001). Both models of SIRT1 activation, which did not alter β-cell function in the absence of fat, resulted in partial protection from the fat-induced decrease in β-cell function (NS vs. control).

Conclusion
These results suggest that SIRT1 is a therapeutic target in decreased β-cell function specifically induced by fat.