bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Combined Influence of Lower Band Chorus and ULF Waves on Radiation Belt Electron Fluxes at Individual L‐Shells
Authors: Simms Laura E. , Engebretson Mark J. , Rodger Craig J. , Dimitrakoudis Stavros , Mann Ian. R. , Chi Peter J. 
Published: April 2021

AbstractWe investigate the timing and relative influence of VLF in the chorus frequency range observed by the DEMETER spacecraft and ULF wave activity from ground stations on daily changes in electron flux (0.23 to over 2.9 MeV) observed by the HEO‐3 spacecraft. At each L‐shell, we use multiple regression to investigate the effects of each wave type and each daily lag independent of the others. We find that reduction and enhancement of electrons occur at different timescales. Chorus power spectral density and ULF wave power are associated with immediate electron decreases on the same day but with flux enhancement 1–2 days later. ULF is nearly always more influential than chorus on both increases and decreases of flux, although chorus is often a significant factor. There was virtually no difference in correlations of ULF Pc3, Pc4, or Pc5 with electron flux. A synergistic interaction between chorus and ULF waves means that enhancement is most effective when both waves are present, pointing to a two‐step process where local acceleration by chorus waves first energizes electrons which are then brought to even higher energies by inward radial diffusion due to ULF waves. However, decreases in flux due to these waves act additively. Chorus and ULF waves combined are most effective at describing changes in electron flux at >1.5 MeV. At lower L (2–3), correlations between ULF and VLF (likely hiss) with electron flux were low. The most successful models, over L = 4–6, explained up to 47.1% of the variation in the data.
Seasonal Variability of Freshwater Plumes in the Eastern Gulf of Guinea as Inferred From Satellite Measurements
Authors: Houndegnonto O. J. , Kolodziejczyk N. , Maes C. , Bourlès B. , Da‐Allada C. Y. , Reul N. 
Published: April 2021

AbstractIn the eastern Gulf of Guinea (GG), freshwater originated from rivers discharges into the ocean and high precipitation rate are key contributors to the upper ocean vertical density stratification, and play a key role in modulating local air‐sea interactions as well as biogeochemical cycle. Nevertheless, the dynamics of the GG freshwater plumes remain poorly documented because of the scarcity of historical, in situ observations and the lack of an ad hoc satellite‐based analysis in this region. Recent advances in remote sensing capabilities from the Soil Moisture and Ocean Salinity (SMOS) satellite mission offer unprecedented coverage and spatiotemporal resolution of Sea Surface Salinity (SSS) in the GG. Using SMOS SSS and available in situ measurements, the seasonal variability of freshwater plumes and associated physical mechanisms controlling their seasonal cycle are presented and analyzed. Freshwater plumes in the GG follow two dynamical regimes. They present maximum offshore extension during boreal winter and exhibit minimum signature during summer. In the northeastern GG, SSS variability is mainly explained by high precipitation rate and Niger River runoff during winter, while during late summer, SSS is mainly driven by horizontal advection. In contrast, southeast of GG, freshwater plumes are mainly supplied by Congo River runoff. From September to March, SSS variability is driven by zonal advection, with a major contribution from Ekman wind‐driven currents. During spring‐summer, the observed SSS increase is likely explained by entrainment and vertical mixing. SSS budget and freshwater advection processes are discussed in the context of the shallow stratification induced by freshwater.
Differences in the Diurnal Variation of Precipitation Estimated by Spaceborne Radar, Passive Microwave Radiometer, and IMERG
Authors: Hayden Lindsey , Liu Chuntao 
Published: April 2021

AbstractAccurate, high‐resolution measurements of the precipitation diurnal cycle are important for understanding local variations in precipitation and the underlying processes which cause them. Combining 16 years of measurements from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and 4 years from the Global Precipitation Measurement (GPM) Dual‐frequency Precipitation Radar (DPR) creates a 20‐year mean of near surface precipitation rate at 0.1° × 0.1°, hourly resolution from 35°N to 35°S. Similar data sets are created using the same proportions of the TRMM Microwave Imager and GPM Microwave Imager measurements, and 18 years of the Integrated Multi‐satellitE Retrievals for GPM (IMERG) precipitation product. The phase and amplitude of the diurnal variation from each data set are calculated at each grid point using a fast Fourier transform (FFT). The satellite data are validated with 14 years of hourly National Climatic Data Center rain gauge measurements over the southeast United States by applying the same FFT method. Spaceborne radar best represents the unaveraged magnitude and diurnal phase measured by the gauges in this region. Time delays are found in precipitation retrievals from passive microwave observations as well as in the IMERG product. The strengths and weaknesses of these high‐resolution data sets in determining the diurnal cycle of precipitation on a climatological scale are discussed across the tropics and subtropics. In general, when compared to PR and DPR retrievals, IMERG overestimates the global precipitation and has varying time lags, which tend to be larger and earlier over regions where organized convective systems are common.
Impacts of Urban Canopy on Two Convective Storms With Contrasting Synoptic Conditions Over Nanjing, China
Authors: Yang Long , Li Qi , Yuan Huiling , Niu Zhixing , Wang Lachun 
Published: April 2021

AbstractDiverse urban‐induced rainfall anomalies highlight the need for improved understanding on extreme rainfall in cities. In this study, we examine urban modification of rainfall over Nanjing, China. Our results are based on climatological analyses of hourly rainfall observations and high‐resolution Weather Research and Forecasting model simulations coupled with different urban physics schemes. A gridded dataset of urban canopy parameters (UCPs) was developed to better characterize the geometrical features of downtown Nanjing. Two convective storms were investigated to shed light on the impacts of urban canopy on spatial and temporal rainfall variabilities for storms with contrasting synoptic conditions. We show that the model simulations coupled with the multi‐layer urban physics scheme and the gridded UCPs can noticeably reduce biases in surface thermal and dynamic fields, but its performance in rainfall patterns varies with storm events. There is a strong convergence zone over the urban‐rural interface induced by building complexes, leading to intensified convection for the storm with strong synoptic conditions but bifurcated moisture fluxes for the storm with weak synoptic conditions. Lagrangian analysis of storm elements further illustrates the role of urban canopy in deflecting storm cells approaching the city for the storm under weak synoptic conditions. The magnitudes of positive rainfall anomalies induced by urban canopy range from 60% to 100% of the storm‐total rainfall. Our study highlights the necessity of improved characterization of urban canopy and the perturbed atmospheric boundary layer processes in examining urban convective rainfall.
Obliquity‐Driven CO2 Exchange Between Mars' Atmosphere, Regolith, and Polar Cap
Authors: Buhler P. B. , Piqueux S. 
Published: April 2021

AbstractDiscerning the total mass of Mars’ obliquity‐timescale (∼105‐year) exchangeable CO2 inventory has been elusive for decades due to the unknown adsorptive capacity of its regolith. Now, however, the stratigraphy of Mars’ recently discovered South Polar Massive CO2 Ice Deposit (MCID) provides a record of orbit‐driven CO2 exchange between its polar cap, atmosphere, and regolith with sufficient constraint to calculate the adsorptive capacity of its regolith and therefore the total mass of its exchangeable CO2 inventory. We use a numerical climate model and Markov Chain Monte Carlo analysis to show that the observed MCID stratigraphic record is most consistent with a mobile CO2 inventory of kg ( mbar, 68% confidence interval) that exchanges on obliquity timescales. We find that adsorptive CO2 exchange with the regolith on obliquity timescales likely occurs in the depth range of >∼200 m to <∼1 km, with the deeper bound set by thermal processes and adsorptive surface availability. Our best‐fit model yields a peak mean annual surface pressure 40% lower than CO2 exchange models that neglect an adsorbing regolith. We provide machine‐readable text files of our results to aid future study of Mars’ climate.
Hillslopes in Headwaters of Qinghai‐Tibetan Plateau as Hotspots for Subsurface Dissolved Organic Carbon Processing During Permafrost Thaw
Authors: Sun Yuqin , Clauson Kale , Zhou Min , Sun Ziyong , Zheng Chunmiao , Zheng Yan 
Published: April 2021

AbstractClimate warming has accelerated thawing of northern permafrost, resulting in changes to the supply of dissolved organic carbon (DOC) to inland waters with uncertain fate. Extensive surface water and groundwater interactions occur in alpine permafrost watersheds and likely influence DOC processing differently than systems with limited interactions. Here, we quantify and characterize DOC in waters collected from eight types of water sampled across a small (25 km2) alpine (elevation 2,960–4,820 m a.s.l) watershed in the Qinghai‐Tibetan Plateau (QTP) containing variably degraded permafrost. Three types of water (thermokarst ponds, red mud gully, and seepage‐I) contained high DOC concentrations (5.2–22.6 mg L−1, n = 38), with carbon contributions predominantly from frozen soil meltwater. Spatial patterns of DOC in stream (0.3–4.8 mg L−1, n = 41), and subsurface waters (0.4–3.8 mg L−1, n = 34), all contained frozen soil meltwater carbon as constrained by δ18O and electrical conductivity, reflecting surface‐groundwater exchanges in the upper‐, middle‐, and lower stretches of the watershed. Further, patterns of increasing DOC loss in subsurface waters with decreased proportions of protein‐like organic matter and specific UV absorbance at 254 nm, suggest subsurface microbial processing. Using previously established biodegradation DOC kinetics (0.06 day−1) from the QTP, the groundwater transit time is estimated to be between 6 and 20 days based on DOC loss changes of 32% and 74% for July and September, respectively. Mass balance of DOC inputs and export fluxes demonstrate nearly half of all DOC was lost in this small watershed, indicating hillslopes are hotspots for DOC processing, with subsurface environments playing a key role.
Basement‐Cover Decoupling During the Inversion of a Hyperextended Basin: Insights From the Eastern Pyrenees
Authors: Ducoux M. , Jolivet L. , Cagnard F. , Baudin T. 
Published: April 2021

AbstractDeformation processes related to early stages of collisional belts, especially the inversion of rifted systems remain poorly constrained, partly because evidence of these processes is usually obliterated during the subsequent collision. The Pyrenean belt resulting from the inversion of a Cretaceous hyperextended rifted margin associated with a high‐temperature and low‐pressure metamorphism in the Internal Metamorphic Zone (IMZ), is a good example for studying the early stage of orogenic deformation. This study is focused on the Eastern Pyrenees where the relation between inverted Mesozoic rifted basins and their basement are well‐preserved. By using maximum temperatures (Tmax) estimated by the Raman Spectroscopy of Carbonaceous Materials geothermometer and structural data, we describe the spatial distribution of the various tectono‐metamorphic units.Tmaxrecorded in the sedimentary cover exposed to the north and to the south of a Paleozoic basement block (Agly massif), exceed 550°C, while the Paleozoic metasediments and their autochthonous Mesozoic cover showTmax < 350°C. The metamorphic sedimentary cover is affected by ductile deformation, while the basement is only affected by brittle deformation. Post‐metamorphism breccias are observed between the basement and the metamorphic sedimentary cover, which are interpreted as a décollement level in the Upper Triassic evaporites. Unlike previous models suggesting that the basement block separated two metamorphic basins (Boucheville and Bas Agly) during rifting, we propose a large displacement of a single metamorphic basin by a large thrust above the basement block. This novel interpretation emphasizes the general allochthonous position of the former hyperextended rift basin (IMZ) thrusted along a decoupling layer.
Mitochondrial quality control protects photoreceptors against oxidative stress in the H2O2-induced models of retinal degeneration diseases
Authors: Zhou Biting , Fang Lijun , Dong Yanli , Yang Juhua , Chen Xiaole , Zhang Nanwen , Zhu Yihua , Huang Tianwen 
Published: April 2021

AbstractRetinal degeneration diseases (RDDs) are common and devastating eye diseases characterized by the degeneration of photoreceptors, which are highly associated with oxidative stress. Previous studies reported that mitochondrial dysfunction is associated with various neurodegenerative diseases. However, the role of mitochondrial proteostasis mainly regulated by mitophagy and mitochondrial unfolded protein response (mtUPR) in RDDs is unclear. We hypothesized that the mitochondrial proteostasis is neuroprotective against oxidative injury in RDDs. In this study, the data from our hydrogen peroxide (H2O2)-treated mouse retinal cone cell line (661w) model of RDDs showed that nicotinamide riboside (NR)-activated mitophagy increased the expression of LC3B II and PINK1, and promoted the co-localization of LC3 and mitochondria, as well as PINK1 and Parkin in the H2O2-treated 661w cells. However, the NR-induced mitophagy was remarkably reversed by chloroquine (CQ) and cyclosporine A (CsA), mitophagic inhibitors. In addition, doxycycline (DOX), an inducer of mtUPR, up-regulated the expression of HSP60 and CHOP, the key proteins of mtUPR. Activation of both mitophagy and mtUPR increased the cell viability and reduced the level of apoptosis and oxidative damage in the H2O2-treated 661w cells. Furthermore, both mitophagy and mtUPR played a protective effect on mitochondria by increasing mitochondrial membrane potential and maintaining mitochondrial mass. By contrast, the inhibition of mitophagy by CQ or CsA reversed the beneficial effect of mitophagy in the H2O2-treated 661w cells. Together, our study suggests that the mitophagy and mtUPR pathways may serve as new therapeutic targets to delay the progression of RDDs through enhancing mitochondrial proteostasis.
Association of sleep duration in middle and old age with incidence of dementia
Authors: Sabia Séverine , Fayosse Aurore , Dumurgier Julien , van Hees Vincent T. , Paquet Claire , Sommerlad Andrew , Kivimäki Mika , Dugravot Aline , Singh-Manoux Archana 
Published: April 2021

AbstractSleep dysregulation is a feature of dementia but it remains unclear whether sleep duration prior to old age is associated with dementia incidence. Using data from 7959 participants of the Whitehall II study, we examined the association between sleep duration and incidence of dementia (521 diagnosed cases) using a 25-year follow-up. Here we report higher dementia risk associated with a sleep duration of six hours or less at age 50 and 60, compared with a normal (7 h) sleep duration, although this was imprecisely estimated for sleep duration at age 70 (hazard ratios (HR) 1.22 (95% confidence interval 1.01–1.48), 1.37 (1.10–1.72), and 1.24 (0.98–1.57), respectively). Persistent short sleep duration at age 50, 60, and 70 compared to persistent normal sleep duration was also associated with a 30% increased dementia risk independently of sociodemographic, behavioural, cardiometabolic, and mental health factors. These findings suggest that short sleep duration in midlife is associated with an increased risk of late-onset dementia.
Structure of the far-red light utilizing photosystem I of Acaryochloris marina
Authors: Hamaguchi Tasuku , Kawakami Keisuke , Shinzawa-Itoh Kyoko , Inoue-Kashino Natsuko , Itoh Shigeru , Ifuku Kentaro , Yamashita Eiki , Maeda Kou , Yonekura Koji , Kashino Yasuhiro 
Published: April 2021

AbstractAcaryochloris marina is one of the cyanobacterial species that can use far-red light to drive photochemical reactions for oxygenic photosynthesis. Here, we report the structure of A. marina photosystem I (PSI) reaction center, determined by cryo-electron microscopy at 2.58 Å resolution. The structure reveals an arrangement of electron carriers and light-harvesting pigments distinct from other type I reaction centers. The paired chlorophyll, or special pair (also referred to as P740 in this case), is a dimer of chlorophyll d and its epimer chlorophyll d′. The primary electron acceptor is pheophytin a, a metal-less chlorin. We show the architecture of this PSI reaction center is composed of 11 subunits and we identify key components that help explain how the low energy yield from far-red light is efficiently utilized for driving oxygenic photosynthesis.
Layered-rocksalt intergrown cathode for high-capacity zero-strain battery operation
Authors: Li Ning , Sun Meiling , Kan Wang Hay , Zhuo Zengqing , Hwang Sooyeon , Renfrew Sara E. , Avdeev Maxim , Huq Ashfia , McCloskey Bryan D. , Su Dong , Yang Wanli , Tong Wei 
Published: April 2021

AbstractThe dependence on lithium-ion batteries leads to a pressing demand for advanced cathode materials. We demonstrate a new concept of layered-rocksalt intergrown structure that harnesses the combined figures of merit from each phase, including high capacity of layered and rocksalt phases, good kinetics of layered oxide and structural advantage of rocksalt. Based on this concept, lithium nickel ruthenium oxide of a main layered structure (R$$\bar{3}$$

3

¯

m) with intergrown rocksalt (Fm$$\bar{3}$$

3

¯

m) is developed, which delivers a high capacity with good rate performance. The interwoven rocksalt structure successfully prevents the anisotropic structural change that is typical for layered oxide, enabling a nearly zero-strain operation upon high-capacity cycling. Furthermore, a design principle is successfully extrapolated and experimentally verified in a series of compositions. Here, we show the success of such layered-rocksalt intergrown structure exemplifies a new battery electrode design concept and opens up a vast space of compositions to develop high-performance intergrown cathode materials.
An integrative analysis of the age-associated multi-omic landscape across cancers
Authors: Chatsirisupachai Kasit , Lesluyes Tom , Paraoan Luminita , Van Loo Peter , de Magalhães João Pedro 
Published: April 2021

AbstractAge is the most important risk factor for cancer, as cancer incidence and mortality increase with age. However, how molecular alterations in tumours differ among patients of different age remains largely unexplored. Here, using data from The Cancer Genome Atlas, we comprehensively characterise genomic, transcriptomic and epigenetic alterations in relation to patients’ age across cancer types. We show that tumours from older patients present an overall increase in genomic instability, somatic copy-number alterations (SCNAs) and somatic mutations. Age-associated SCNAs and mutations are identified in several cancer-driver genes across different cancer types. The largest age-related genomic differences are found in gliomas and endometrial cancer. We identify age-related global transcriptomic changes and demonstrate that these genes are in part regulated by age-associated DNA methylation changes. This study provides a comprehensive, multi-omics view of age-associated alterations in cancer and underscores age as an important factor to consider in cancer research and clinical practice.
Growth hormone deficiency testing and treatment following mild traumatic brain injury
Authors: Mercier Leah J. , Kruger Natalia , Le Quynk B. , Fung Tak S. , Kline Gregory A. , Debert Chantel T. 
Published: April 2021

AbstractPituitary dysfunction, specifically growth hormone (GH) deficiency, can occur following traumatic brain injury. Our objective was to characterize the prevalence of GH deficiency (GHD) testing and response to recombinant human GH (rhGH) treatment in adults with persistent symptoms following mild traumatic brain injury (mTBI) referred for assessment of pituitary dysfunction. A retrospective chart review was conducted of patients seen at an outpatient brain injury clinic with a diagnosis of mTBI and persistent post-concussive symptoms who were referred to endocrinology. Clinical assessments of symptoms were collected. Investigations and results of GHD were collected, including initiation of rhGH treatment and treatment response. Of the 253 patients seen in both brain injury and endocrinology clinics, 97 with mTBI were referred for investigation of pituitary dysfunction and 73 (75%) had dynamic testing for assessment of GHD. Of the 26 individuals diagnosed with GHD, 23 (88%) started rhGH. GH therapy was inconsistently offered based on interpretation of GH dynamic testing results. Of those who started rhGH, 18 (78%) had a useful treatment response. This study suggests that clinical management of these patients is varied, highlighting a need for clear guidelines for the diagnosis and management of GHD following mTBI.
Reaction lumping in metabolic networks for application with thermodynamic metabolic flux analysis
Authors: Seep Lea , Razaghi-Moghadam Zahra , Nikoloski Zoran 
Published: April 2021

AbstractThermodynamic metabolic flux analysis (TMFA) can narrow down the space of steady-state flux distributions, but requires knowledge of the standard Gibbs free energy for the modelled reactions. The latter are often not available due to unknown Gibbs free energy change of formation$$, {\Delta }_{f} G^{0}$$,ΔfG0, of metabolites. To optimize the usage of data on thermodynamics in constraining a model, reaction lumping has been proposed to eliminate metabolites with unknown$${\Delta }_{f} G^{0}$$ΔfG0. However, the lumping procedure has not been formalized nor implemented for systematic identification of lumped reactions. Here, we propose, implement, and test a combined procedure for reaction lumping, applicable to genome-scale metabolic models. It is based on identification of groups of metabolites with unknown$${\Delta }_{f} G^{0}$$ΔfG0whose elimination can be conducted independently of the others via: (1)group implementation, aiming to eliminate an entire such group, and, if this is infeasible, (2) asequential implementationto ensure that a maximal number of metabolites with unknown$${\Delta }_{f} G^{0}$$ΔfG0are eliminated. Our comparative analysis with genome-scale metabolic models ofEscherichia coli,Bacillus subtilis,andHomo sapiensshows that the combined procedure provides an efficient means for systematic identification of lumped reactions. We also demonstrate that TMFA applied to models with reactions lumped according to the proposed procedure lead to more precise predictions in comparison to the original models. The provided implementation thus ensures the reproducibility of the findings and their application with standard TMFA.