bluuebunny/crossref_metadata_2025_split huggingface dataset:
Divergence Measures and Detection Performance for Dispersive Targets in SAR
Authors: Gilman Mikhail , Tsynkov Semyon 
Published: December 2020

AbstractWhen electromagnetic waves impinge on objects with complex geometries and/or internal structure, we can observe scattering that is distributed in time rather than instantaneous. To detect and characterize such targets, we build the coordinate‐delay synthetic aperture radar (cdSAR) images by adding a delay term to the standard SAR matched filter. In order to apply this approach to the case of extended targets where the image intensity and phase are subject to strong and rapid variations (the phenomenon called speckle), we sample the cdSAR image at several coordinate‐delay “points” in the vicinity of the scatterer location. The discrimination between the instantaneous and delayed targets is realized through autocorrelation analysis of this sample. Because of the statistical properties of speckle, misclassification errors are inevitable. Hence, prediction of the error rate as a function of system and target parameters becomes an important problem. While Monte Carlo simulations can generate the ensembles of data for direct calculation of the error rate, this approach is computationally demanding because of its slow convergence. In order to simplify the prediction of the error rate, we employ statistical divergence measures, namely, the Hellinger distance and Kullback‐Leibler divergence. These divergence measures are calculated directly from the theoretical models of reflectivity of extended targets that we want to distinguish. We empirically establish a linear relation between the misclassification rate and the Hellinger distance for a certain class of simple target models. This relation allows us to make predictions of the error rate without performing the Monte Carlo simulations.
The Effect of Streamflow, Ambient Groundwater, and Sediment Anisotropy on Hyporheic Zone Characteristics in Alternate Bars
Authors: Monofy A. , Boano F. 
Published: December 2020

AbstractThe hyporheic exchange is the main driver for the biogeochemical transformations of nutrients within a river bed. The current study addresses the variations in hyporheic zone (HZ) characteristics in alternate bars due to different streamflow, ambient groundwater, and sediment anisotropy. Several simulations, using a sequentially coupled surface water‐groundwater model of a synthetic reach with fully developed alternate bars morphology, were performed. Two HZs exist within the streambed; a shallow zone that is more linked to surface water, and a deep one that is more influenced by the groundwater variations. Increasing streamflow, and therefore bar submergence, decreases the hyporheic flow. The residence times distribution is bimodal, which implies the existence of two HZs . This bimodality is enhanced by anisotropic sediment conditions, while it is much milder in isotropic ones. The shallow zone residence times increase when streamflow value rises, while the residence times in the deep HZ are less affected. The mean and median residence times decrease by increasing streamflow in partially submerged case, and they are larger in fully submerged case. The hyporheic flow, area, residence times, and extent decrease by increasing groundwater fluxes. The deep zone is the most affected by the groundwater fluxes. Hyporheic flow and extent values are significantly larger in isotropic conditions than in anisotropic ones. The change in residence times values is different between the deep and shallow zones. A predictive model is driven to predict the hyporheic flux, residence times, and hyporheic depths dependence on bar submergence, ambient groundwater, and sediment anisotropy.
Spatial and Temporal Variability of Diffusive CO2 and CH4 Fluxes From the Amazonian Reservoir Petit‐Saut (French Guiana) Reveals the Importance of Allochthonous Inputs for Long‐Term C Emissions
Authors: Colas Fanny , Chanudet Vincent , Daufresne Martin , Buchet Lucie , Vigouroux Régis , Bonnet Angélique , Jacob Frederick , Baudoin Jean‐Marc 
Published: December 2020

AbstractVariability in greenhouse gas emissions from reservoirs creates uncertainty in global estimates of C emissions from reservoirs. This study examines the temporal and spatial variability in CO2 and CH4 surface water concentrations and diffusive fluxes from an Amazonian reservoir using an original data set combining both a high temporal (1 central site × 22 years) and spatial (44 sites × 1 season) resolution monitoring. The gas concentrations at the central site decreased over time and suggested reduced bioavailability of C in the initial flooded soil but exhibited strong seasonal variation. Not accounting for this variability may result in uncertainties in estimates of annual concentrations (ranging from −68.9% to +260% for CH4 and from −71.5% to +156% for CO2) and thus in estimates of diffusive gas emissions. Gas concentrations and diffusive fluxes exhibited high spatial variability in the reservoir, 24 years after impoundment. In particular, diffusive fluxes were higher in littoral and transitional areas than in open areas, suggesting a large contribution of allochthonous C to current gaseous emissions. Not accounting for this spatial variability in diffusive fluxes may underestimate the total emissions expressed in CO2 equivalents from the whole reservoir by 50.7%. Our study stresses the importance of well‐resolved temporal and spatial monitoring to provide reliable estimated of C emissions and a comprehensive understanding of the processes involved; both of these inputs are needed to support decision‐making for developing energy strategies.
Define East Asian Monsoon Annual Cycle via a Self‐Organizing Map‐Based Approach
Authors: Dai Lun , Cheng Tat Fan , Lu Mengqian 
Published: December 2020

AbstractMethods to define the East Asian monsoon usually involve ad hoc and diverse criteria. This study adopts a simple and coherent approach based on the self‐organizing map to systematically derive the monsoon annual cycle based on 850‐hPa wind fields. The derived onset dates in the warm season agree well with the literature despite lacking documentation for winter‐season stages. Linear regression suggests an inverse relationship between the length of the Spring (Meiyu) stage and that of the Pre‐Meiyu (Mid‐summer) stage, suggesting predictability of the Meiyu and Fall onsets. The Aleutian Low, the western North Pacific subtropical high, and the upper‐level westerlies play important roles in the Spring, Pre‐Meiyu, and Meiyu onsets. Observations reveal strong rain belt events form right after the monsoonal wind onsets in the warm season. The proposed approach to deriving monsoon stages and onsets would be useful for monsoon climate studies and operational monsoon diagnosis and forecasting.
Effects of Substorms on High‐Latitude Upper Thermospheric Winds
Authors: Zou Ying , Lyons Larry , Conde Mark , Varney Roger , Angelopoulos Vassilis , Mende Stephen 
Published: December 2020

AbstractDuring magnetospheric substorms, high‐latitude ionospheric plasma convection is known to change dramatically. How upper thermospheric winds change, however, has not been well understood, and conflicting conclusions have been reported. Here, we study the effect of substorms on high‐latitude upper thermospheric winds by taking advantage of a chain of scanning Doppler imagers (SDIs), THEMIS all‐sky imagers (ASIs), and the Poker Flat incoherent scatter radar (PFISR). SDIs provide mosaics of wind dynamics in response to substorms in two dimensions in space and as a function of time, while ASIs and PFISR concurrently monitor auroral emissions and ionospheric parameters. During the substorm growth phase, the classical two‐cell global circulation of neutral winds intensifies. After substorm onset, the zonal component of these winds is strongly suppressed in the midnight sector, whereas away from the midnight sector two‐cell circulation of winds is enhanced. Both pre and postonset enhancements are ≥100 m/s above the quiet‐time value, and postonset enhancement occurs over a broader latitude and local‐time area than preonset enhancement. The meridional wind component in the midnight and postmidnight sectors is accelerated southward to subauroral latitudes. Our findings suggest that substorms significantly modify the upper‐thermospheric wind circulation by changing the wind direction and speed and therefore are important for the entire magnetosphere‐ionosphere‐thermosphere system.
Tropospheric Ozone Variability Over Hong Kong Based on Recent 20 years (2000–2019) Ozonesonde Observation
Authors: Liao Zhiheng , Ling Zhenhao , Gao Meng , Sun Jiaren , Zhao Wei , Ma Pengkun , Quan Jiannong , Fan Shaojia 
Published: December 2020

AbstractThe recent 20 years (2000–2019) ozonesonde profiles recorded at the Hong Kong Observatory are analyzed to study the Tropospheric Ozone (TropO3) variability over Hong Kong, South China. The TropO3 profiles are described without the constraints of traditional monthly averages; they are clustered based on a Self‐Organizing Map (SOM) to explore the short‐term variability, and separated into two 10‐year periods to investigate the long‐term variability based on pooled statistical analysis. The roles of precursor emissions, dynamic transport, and photochemical formation in multiple‐timescale TropO3 variability are further evaluated with the aid of meteorological and satellite data, surface observation, emission inventory, and backward trajectory analysis. The results suggest that TropO3 over Hong Kong has a seasonal and vertical distribution featuring a widely recognized spring maximum. The SOM‐based clustering analysis emphasizes a strong dependence of short‐term variability in TropO3 profile patterns on cross‐latitude transport conditions, including rich‐O3 transport from midlatitude region and poor‐O3 transport from tropics. However, high O3 levels throughout the troposphere (usually in early spring) are largely due to the combination of stratospheric intrusion and biomass burning. During the whole study period, the O3 concentrations have increased substantially in the lower troposphere. Springtime wildfire‐related emissions over the upwind Indochina Peninsula are responsible for the lower free‐tropospheric O3 increases. In contrast, the boundary‐layer O3 uptrends with a larger increasing rate near the surface are mostly attributed to the reduced NO titration effect due to the sharp reduction of NOx emissions.
Mobilization of Geochemical Elements to Surface Water in the Active Layer of Permafrost in the Russian Arctic
Authors: Ji Xiaowen , Abakumov Evgeny , Polyakov Vyacheslav , Xie Xianchuan 
Published: December 2020

AbstractThe predicted increase of ground temperatures in the Arctic results in the deepening of the active layer and intensification of geochemical processes. Determining the responses of riparian soil systems to surrounding hydrological flows is important for understanding seasonal changes in hydrological processes. In this study, one soil core from a polygon rim (close to the Taz River, TA) and two soil cores from a riverine terrace (close to the Syoyakha River, SY and Murtyyakha River, MU) in Western Siberia, Russia, and their suprapermafrost water, adjacent surface flows, and river water were sampled for analysis of geochemical elements. Results showed that most elements above their respective detection limits began accumulating in the underlying gleyed layer during September‐October in response to the deepest thaw in the active layer. This study focused on the highly mobile elements in the deepest layer; and found that the transport of organic matter in the upper layer carried these elements to both surface water ponds/flows and suprapermafrost water, and further, to the rivers. The efflux of released elements from surface soil to surrounding surface water appeared to be low. The best linear correlation for both surface flows and river water was with Mn; therefore, Mn may be a proxy for predicting the processes occurring within the active layer during the annual summer‐autumn thaw. Moreover, landscapes with different ice contents may experience changes in the elements transported to surface waters. A general conceptual model for the response of elements to the thawing‐freezing process of the active layer is established.
Tree Rings and Observations Suggest No Stable Cycles in Sierra Nevada Cool‐Season Precipitation
Authors: Williams A. P. , Anchukaitis K. J. , Woodhouse C. A. , Meko D. M. , Cook B. I. , Bolles K. , Cook E. R. 
Published: December 2020

AbstractCalifornia’s water resources rely heavily on cool‐season (November–March) precipitation in the Sierra Nevada. Interannual variability is highly volatile and seasonal forecasting has little to no skill, making water management particularly challenging. Over 1902–2020, Sierra Nevada cool‐season precipitation totals exhibited significant 2.2‐ and 13–15‐year cycles, accounting for approximately 40% of total variability and perhaps signifying potential as seasonal forecasting tools. However, the underlying climate dynamics are not well understood and it is unclear whether these cycles are stable over the long term. We use tree rings to reconstruct Sierra Nevada cool‐season precipitation back to 1400. The reconstruction is skillful, accounting for 55%–74% of observed variability and capturing the 20th‐century 2.2‐ and 13–15‐year cycles. Prior to 1900, the reconstruction indicates no other century‐long periods of significant spectral power in the 2.2‐ or 13–15‐year bands. The reconstruction does indicate significant cyclicity over other extended periods of several decades or longer, however, with dominant periodicities in the ranges of 2.1–2.7 and 3.5–8 years. The late 1700s through 1800s exhibited the highest‐amplitude cycles in the reconstruction, with periodicities of 2.4 and 5.7–7.4 years. The reconstruction should serve to caution against extrapolating the observed 2.2‐ and 13–15‐year cycles to guide future expectations. On the other hand, observations and the reconstruction suggest that interannual variability of Sierra Nevada cool‐season precipitation is not a purely white noise process and research should aim to diagnose the dynamical drivers of extended periods of cyclicity in this critical natural resource.
Nuclear spin coupling crossover in dense molecular hydrogen
Authors: Meier Thomas , Laniel Dominique , Pena-Alvarez Miriam , Trybel Florian , Khandarkhaeva Saiana , Krupp Alena , Jacobs Jeroen , Dubrovinskaia Natalia , Dubrovinsky Leonid 
Published: December 2020

AbstractOne of the most striking properties of molecular hydrogen is the coupling between molecular rotational properties and nuclear spin orientations, giving rise to the spin isomers ortho- and para-hydrogen. At high pressure, as intermolecular interactions increase significantly, the free rotation of H2 molecules is increasingly hindered, and consequently a modification of the coupling between molecular rotational properties and the nuclear spin system can be anticipated. To date, high-pressure experimental methods have not been able to observe nuclear spin states at pressures approaching 100 GPa (Meier, Annu. Rep. NMR Spectrosc. 94:1–74, 2017; Meier, Prog. Nucl. Magn. Reson. Spectrosc. 106–107:26–36, 2018) and consequently the effect of high pressure on the nuclear spin statistics could not be directly measured. Here, we present in-situ high-pressure nuclear magnetic resonance data on molecular hydrogen in its hexagonal phase I up to 123 GPa at room temperature. While our measurements confirm the presence of ortho-hydrogen at low pressures, above 70 GPa, we observe a crossover in the nuclear spin statistics from a spin-1 quadrupolar to a spin-1/2 dipolar system, evidencing the loss of spin isomer distinction. These observations represent a unique case of a nuclear spin crossover phenomenon in quantum solids.
Differential cell adhesion implemented by Drosophila Toll corrects local distortions of the anterior-posterior compartment boundary
Authors: Iijima Norihiro , Sato Katsuhiko , Kuranaga Erina , Umetsu Daiki 
Published: December 2020

AbstractMaintaining lineage restriction boundaries in proliferating tissues is vital to animal development. A long-standing thermodynamics theory, the differential adhesion hypothesis, attributes cell sorting phenomena to differentially expressed adhesion molecules. However, the contribution of the differential adhesion system during tissue morphogenesis has been unsubstantiated despite substantial theoretical support. Here, we report that Toll-1, a transmembrane receptor protein, acts as a differentially expressed adhesion molecule that straightens the fluctuating anteroposterior compartment boundary in the abdominal epidermal epithelium of the Drosophila pupa. Toll-1 is expressed across the entire posterior compartment under the control of the selector gene engrailed and displays a sharp expression boundary that coincides with the compartment boundary. Toll-1 corrects local distortions of the boundary in the absence of cable-like Myosin II enrichment along the boundary. The reinforced adhesion of homotypic cell contacts, together with pulsed cell contraction, achieves a biased vertex sliding action by resisting the separation of homotypic cell contacts in boundary cells. This work reveals a self-organizing system that integrates a differential adhesion system with pulsed contraction of cells to maintain lineage restriction boundaries.
Uptake of monoaromatic hydrocarbons during biodegradation by FadL channel-mediated lateral diffusion
Authors: Somboon Kamolrat , Doble Anne , Bulmer David , Baslé Arnaud , Khalid Syma , van den Berg Bert 
Published: December 2020

AbstractIn modern societies, biodegradation of hydrophobic pollutants generated by industry is important for environmental and human health. In Gram-negative bacteria, biodegradation depends on facilitated diffusion of the pollutant substrates into the cell, mediated by specialised outer membrane (OM) channels. Here we show, via a combined experimental and computational approach, that the uptake of monoaromatic hydrocarbons such as toluene in Pseudomonas putida F1 (PpF1) occurs via lateral diffusion through FadL channels. Contrary to classical diffusion channels via which polar substrates move directly into the periplasmic space, PpF1 TodX and CymD direct their hydrophobic substrates into the OM via a lateral opening in the channel wall, bypassing the polar barrier formed by the lipopolysaccharide leaflet on the cell surface. Our study suggests that lateral diffusion of hydrophobic molecules is the modus operandi of all FadL channels, with potential implications for diverse areas such as biodegradation, quorum sensing and gut biology.
A flexible computational pipeline for research analyses of unsolved clinical exome cases
Authors: Lassmann Timo , Francis Richard W. , Weeks Alexia , Tang Dave , Jamieson Sarra E. , Broley Stephanie , Dawkins Hugh J. S. , Dreyer Lauren , Goldblatt Jack , Groza Tudor , Kamien Benjamin , Kiraly-Borri Cathy , McKenzie Fiona , Murphy Lesley , Pachter Nicholas , Pathak Gargi , Poulton Cathryn , Samanek Amanda , Skoss Rachel , Slee Jennie , Townshend Sharron , Ward Michelle , Baynam Gareth S. , Blackwell Jenefer M. 
Published: December 2020

AbstractExome sequencing has enabled molecular diagnoses for rare disease patients but often with initial diagnostic rates of ~25−30%. Here we develop a robust computational pipeline to rank variants for reassessment of unsolved rare disease patients. A comprehensive web-based patient report is generated in which all deleterious variants can be filtered by gene, variant characteristics, OMIM disease and Phenolyzer scores, and all are annotated with an ACMG classification and links to ClinVar. The pipeline ranked 21/34 previously diagnosed variants as top, with 26 in total ranked ≤7th, 3 ranked ≥13th; 5 failed the pipeline filters. Pathogenic/likely pathogenic variants by ACMG criteria were identified for 22/145 unsolved cases, and a previously undefined candidate disease variant for 27/145. This open access pipeline supports the partnership between clinical and research laboratories to improve the diagnosis of unsolved exomes. It provides a flexible framework for iterative developments to further improve diagnosis.
Design and evaluation of a data anonymization pipeline to promote Open Science on COVID-19
Authors: Jakob Carolin E. M. , Kohlmayer Florian , Meurers Thierry , Vehreschild Jörg Janne , Prasser Fabian 
Published: December 2020

AbstractThe Lean European Open Survey on SARS-CoV-2 Infected Patients (LEOSS) is a European registry for studying the epidemiology and clinical course of COVID-19. To support evidence-generation at the rapid pace required in a pandemic, LEOSS follows an Open Science approach, making data available to the public in real-time. To protect patient privacy, quantitative anonymization procedures are used to protect the continuously published data stream consisting of 16 variables on the course and therapy of COVID-19 from singling out, inference and linkage attacks. We investigated the bias introduced by this process and found that it has very little impact on the quality of output data. Current laws do not specify requirements for the application of formal anonymization methods, there is a lack of guidelines with clear recommendations and few real-world applications of quantitative anonymization procedures have been described in the literature. We therefore believe that our work can help others with developing urgently needed anonymization pipelines for their projects.
Augmenting aesthetic chills using a wearable prosthesis improves their downstream effects on reward and social cognition
Authors: Haar A. J. H. , Jain A. , Schoeller F. , Maes P. 
Published: December 2020

AbstractPrevious studies on aesthetic chills (i.e., psychogenic shivers) demonstrate their positive effects on stress, pleasure, and social cognition. We tested whether we could artificially enhance this emotion and its downstream effects by intervening on its somatic markers using wearable technology. We built a device generating cold and vibrotactile sensations down the spine of subjects in temporal conjunction with a chill-eliciting audiovisual stimulus, enhancing the somatosensation of cold underlying aesthetic chills. Results suggest that participants wearing the device experienced significantly more chills, and chills of greater intensity. Further, these subjects reported sharing the feelings expressed in the stimulus to a greater degree, and felt more pleasure during the experience. These preliminary results demonstrate that emotion prosthetics and somatosensory interfaces offer new possibilities of modulating human emotions from the bottom-up (body to mind). Future challenges will include testing the device on a larger sample and diversifying the type of stimuli to account for negatively valenced chills and intercultural differences. Interoceptive technologies offer a new paradigm for affective neuroscience, allowing controlled intervention on conscious feelings and their downstream effects on higher-order cognition.