bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of flow past a sphere on a rough bed using smoothed particle hydrodynamics (SPH)
Authors: Bartzke Gerhard , Fourtakas Georgios , Canelas Ricardo , Rogers Benedict D. , Huhn Katrin 
Published: June 2021

AbstractThis paper presents an investigation of flow past a sphere on a rough surface by means of simulation using the meshless numerical method, smoothed particle hydrodynamics (SPH) in the presence of a free surface. A representative of natural and engineered objects is spherical wall-mounted bodies. These are ideal to study the flow conditions around hydraulic structures, boulders, fish habitat structures or even architectural structures. The aim is to understand their effect on the hydrodynamics around the larger object sphere resting on them and their interaction. The Lagrangian particle-based scheme SPH using the open-source code DualSPHysics is validated against datasets from a laboratory-based flume experiment. The validation case was selected from the family of the flow past a sphere test cases since it reproduces the flow features in a simplified manner that can be observed in the vicinity of natural sediment grains or larger bodies. The validation results include flow velocity profiles in the vicinity of the large sphere and comparison with experiment data. The results stand in overall agreement with the experimental velocity and force measurements that demonstrates the applicability of SPH in aquatic environments. An SPH investigation on a rough bed in combination with objects/body near the bed in the presence of a free-surface flow has not been shown before in the literature. This is a novel application with insight into the fluid mechanics made possible by using DualSPHysics solver.
The XGTDL family of survival distributions
Authors: MacKenzie Gilbert , Blagojevic-Bucknall Miliça , Al-tawarah Yasin , Peng Defen 
Published: June 2021

AbstractNon-PH parametric survival modelling is developed within the framework of the multiple logistic function. The family considered comprises three basic models: (a) a PH model, (b) an accelerated life model and (c) a model which is non-proportional hazards and non-accelerated life. The last model, the generalised time-dependent logistic model was described first by the author in 1996 and this model gives its name to the entire family. The family is generalised by means of a Gamma frailty extension which is shown to accommodate crossing hazards data. A further generalisation is the inclusion of a dispersion model. These extensions lead naturally to the concept of a multi-parameter regression model described by Burke and MacKenzie in which the scale and shape parameters are modelled simultaneously as functions of covariates. Where possible, we include the MPR extension in the XGTDL family. Following a simulation study, the new models are used to analyse two sets survival data and the methods are discussed.
An association of ABCG8: rs11887534 polymorphism and HDL-cholesterol response to statin treatment in the Polish population
Authors: Sałacka A. , Boroń A. , Gorący I. , Hornowska I. , Safranow K. , Ciechanowicz A. 
Published: June 2021

AbstractBackgroundVariation in lipid changes in response to statin treatment is associated with genetic polymorphism. Sterolin-1, encoded byABCG5, and sterolin-2, encoded byABCG8, together form a sterol transporter. There are some reports indicating association of rs11887534 (ABCG8:c.55G > C) polymorphism with lipid concentrations, both prior to and after statin treatment. The aim of this study was to analyze both baseline plasma lipids and their concentrations in response to statin treatment with regard toABCG8: rs11887534 polymorphism in Caucasian patients of Polish origin.MethodsThe study group consisted of 170 consecutive adult out-patients treated with atorvastatin or simvastatin for a minimum of 2 months. Concentrations of triglycerides (TG), total cholesterol (TC), LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) were measured before and after statin treatment. TheABCG8polymorphism was identified by mini-sequencing genomic DNA extracted from peripheral blood leukocytes.ResultsThere were no significant differences in regard toABCG8variants for baseline TG, TC, LDL-C and HDL-C as well as for TG, TC or LDL-C concentrations after statin treatment. However, patients carrying at least one C allele showed a decrease in post-statin HDL-C concentrations and the absolute and relative changes between post- and pre-statin HDL-C concentrations were negative in contrast to positive values in wild-type homozygotes.ConclusionsOur results suggest that the c.55C allele of theABCG8: rs11887534 polymorphism might be associated with decrease in HDL-cholesterol in response to statin treatment in Polish patients.
Effect of Late Androgen Replacement Therapy on Erectile Function Through Structural Changes in Castrated Rats
Authors: Kataoka Tomoya , Hotta Yuji , Yamamoto Yuka , Fukamoto Ayako , Takeuchi Madoka , Maeda Yasuhiro , Kimura Kazunori 
Published: June 2021

Abstract

Background
Because androgen replacement therapy (ART) is not performed immediately after the onset of androgen deficiency, the treatment is considered to be late.

Aim
To investigate the effects of late ART, starting 4 weeks after castration of rats, on erectile function and structural changes in the corpus cavernosum.

Methods
Rats were subjected to ART for 4 (Late-ART [4w]) or 8 (Late-ART [8w]) weeks. In either case, rats were assigned to the following groups: castrated (Cast), castrated with subcutaneous administration of testosterone (3 mg/kg/day; Cast+T), and sham (Sham). Cast + T rats received daily subcutaneous doses of testosterone starting 4 weeks after castration for 4 or 8 weeks whereas Sham and Cast rats received only the vehicle.

Outcomes
Erectile function was assessed by evaluating intracavernosal pressure (ICP) and mean arterial pressure (MAP) after electrical stimulation of the cavernous nerve, corporal veno-occlusive function using dynamic infusion cavernosometry, and histology using Masson's trichrome staining.

Results
No increase in the ICP was observed in Cast+T rats in the Late-ART (4w) group (0.47 ± 0.02, P &gt; .05), whereas, in Cast+T rats in the Late-ART (8w) group, there was a significant increase in the ICP/MAP ratio (0.60 ± 0.02, P &lt; .05), drop rate, and smooth muscle/collagen ratio.

Clinical Translation
The present study provides scientific evidence for the effect of late ART on erectile function.

Strengths and Limitations
This study provides insights into the influence of late ART on erectile function through improvements in the structure of corpus cavernosum. The major limitation of this study is the difference in the time required for healing between the humans and rats, which might have a bearing on the translational relevenace of the results.

Conclusions
Late ART could improve erectile function. However, as improvement requires a considerable time period, it is necessary to persist with therapy patiently for optimal results.
Regional Nonlinear Relationships Across the United States Between Drought and Tree‐Ring Width Variability From a Neural Network
Authors: Trevino Aleyda M. , Stine Alexander R. , Huybers Peter 
Published: June 2021

AbstractNeural networks were previously applied to reconstruct climate indices from tree rings but showed mixed results in skill relative to more standard linear methods. A two‐layer neural network is explored for purposes of reconstructing summertime self‐calibrated Palmer Drought Severity Index (scPDSI) across the contiguous United States. Reconstructions using neural networks are more skillful than a linear approach at 75% of the gridboxes if evaluated by the coefficient of efficiency and at 54% when using the Pearson correlation coefficient. The increased reconstruction skill is related to the network capturing nonlinear growth‐climate relationships. In the Southwest, in particular, a nonlinear response function captures a diminishing sensitivity of growth to moisture under wetter conditions, consistent with alleviation of moisture stress. These results indicate somewhat less‐severe and more‐stable incidences of drought over the past two centuries in the U.S. Southwest.
Greenland Blocking Promotes Subtropical North Atlantic Spring Blooms
Authors: Le Chengfeng , Chen Yihui , Lehrter John C. , Hu Chuanmin , Bouman Heather , Cai Wei‐Jun , Qi Lin 
Published: June 2021

AbstractClimate patterns drive broad‐scale patterns of ocean ecosystem productivity. However, the mechanistic connections between regional climate variability and ocean ecosystem responses are not well understood for much of the ocean. By analyzing multi‐decadal atmospheric and oceanic data over the North Atlantic Ocean, we show that the subtropical spring bloom variability is connected to winter Greenland blocking events. The blocking enforces a southward shift of the eddy‐driven jet stream, inducing higher surface westerly winds, causing deeper vertical mixing in the subtropical North Atlantic Ocean in winter and promotes larger spring blooms. These findings reveal the physical mechanisms connecting a predominant climate variability mode in the Arctic with variability in the subtropical spring bloom and highlight the importance of ocean‐atmosphere coupling in shaping the response of oceanic ecosystems to climate variability. Our results also imply a potential teleconnection between rapid Arctic warming over Greenland and phytoplankton variability in the subtropical North Atlantic.
Topographic and Ground‐Ice Controls on Shallow Landsliding in Thawing Arctic Permafrost
Authors: Mithan H. T. , Hales T. C. , Cleall P. J. 
Published: June 2021

AbstractAn increase in Arctic shallow landsliding is a potential consequence of climate warming. Warmer summer‐air temperatures and larger rainfall events drive heat into the active layer, melting ice and decreasing soil shear stress. Topography has the potential to exacerbate landsliding by controlling the distribution of ground ice and the movement of water in the subsurface. We demonstrate that shallow Arctic landslides initiate in zero‐order drainage basins consistent with models of shallow landsliding in non‐permafrost environments. However, the low average slopes and low concavity of Arctic hillslopes cannot create pore‐water pressures high enough to generate landsliding. Instead, two‐dimensional slope stability modeling suggests that the vertical distribution of ground‐ice distributions controls landslide susceptibility. High ground‐ice concentrations close to the potential failure plane act as a stronger control than high average ice volumes or rapid thawing. Our results demonstrate that landslide susceptibility is strongly affected by topographic controls on ground ice and hydrology.
Nonlinear Interaction Between the Drivers of the Monsoon and Summertime Stationary Waves
Authors: Garfinkel Chaim I. , White Ian P. , Gerber Edwin P. , Adam Ori , Jucker Martin 
Published: June 2021

AbstractA moist General Circulation Model is used to investigate the forcing of the Asian monsoon and the associated upper level anticyclone by land‐sea contrast, net horizontal oceanic heat transport, and topography. The monsoonal pattern is not simply the linear additive sum of the response to each forcing; only when all three forcings are included simultaneously does the monsoonal circulation extend westward to India. This nonadditivity impacts the location of the upper level anticyclone, which is shifted eastward and weaker if the forcings are imposed individually. Sahelian precipitation, and also austral summer precipitation over Australia, southern Africa, and South America, are likewise stronger if all forcings are imposed simultaneously. The source of the nonlinearity can be diagnosed using gross moist stability, but appears inconsistent with the land‐sea breeze paradigm. This non‐additivity implies that the question of which forcing is most important may be ill‐posed in many regions.
Modeled Three‐Dimensional Currents and Eddies on an Alongshore‐Variable Barred Beach
Authors: Baker Christine M. , Moulton Melissa , Raubenheimer Britt , Elgar Steve , Kumar Nirnimesh 
Published: June 2021

AbstractCirculation in the nearshore region, which is critical for material transport along the coast and between the surf zone and the inner shelf, includes strong vortical motions. The horizontal length scales and vertical structure associated with vortical motions are not well documented on alongshore‐variable beaches. Here, a three‐dimensional phase‐resolving numerical model, Simulating WAves till SHore (SWASH), is compared with surfzone waves and flows on a barred beach, and is used to investigate surfzone eddies. Model simulations with measured bathymetry reproduce trends in the mean surfzone circulation patterns, including alongshore currents and rip current circulation cells observed for offshore wave heights from 0.5 to 2.0 m and incident wave directions from 0 to 15° relative to shore normal. The length scales of simulated eddies, quantified using the alongshore wavenumber spectra of vertical vorticity, suggest that increasing wave directional spread intensifies small‐scale eddies ((10) m). Simulations with bathymetric variability ranging from alongshore uniform to highly alongshore variable indicate that large‐scale eddies ((100) m) may be enhanced by surfzone bathymetric variability, whereas small‐scale eddies ((10) m) are less dependent on bathymetric variability. The simulated vertical dependence of the magnitude and mean length scale (centroid) of the alongshore wavenumber spectra of vertical vorticity and very low‐frequency (f ≈ 0.005 Hz) currents is weak in the outer surf zone, and decreases toward the shoreline. The vertical dependence in the simulations may be affected by the vertical structure of turbulence, mean shear, and bottom boundary layer dynamics.
Variation in Upper Plate Crustal and Lithospheric Mantle Structure in the Greater and Lesser Antilles From Ambient Noise Tomography
Authors: Schlaphorst D. , Harmon N. , Kendall J. M. , Rychert C. A. , Collier J. , Rietbrock A. , Goes S. ,   the VoiLA Team
Published: June 2021

AbstractThe crust and upper mantle structure of the Greater and Lesser Antilles Arc provides insights into key subduction zone processes in a unique region of slow convergence of old slow‐spreading oceanic lithosphere. We use ambient noise tomography gathered from island broadband seismic stations and the temporary ocean bottom seismometer network installed as part of the Volatile Recycling in the Lesser Antilles experiment to map crustal and upper mantle shear‐wave velocity of the eastern Greater Antilles and the Lesser Antilles Arc. Taking the depth to the 2.0 km/s contour as a proxy, we find sediment thickness up to 15 km in the south in the Grenada and Tobago basins and thinner sediments near the arc and to the north. We observe thicker crust, based on the depth to the 4.0 km/s velocity contour, beneath the arc platforms with the greatest crustal thickness of around 30 km, likely related to crustal addition from arc volcanism through time. There are distinct low velocity zones (4.2–4.4 km/s) in the mantle wedge (30–50 km depth), beneath the Mona Passage, Guadeloupe‐Martinique, and the Grenadines. The Mona passage mantle anomaly may be related to ongoing extension there, while the Guadeloupe‐Martinique and Grenadine anomalies are likely related to fluid flux, upwelling, and/or partial melt related to nearby slab features. The location of the Guadeloupe‐Martinique anomaly is slightly to the south of the obliquely subducted fracture zones. This feature could be explained by either three‐dimensional mantle flow, a gap in the slab, variable slab hydration, and/or melt dynamics including ponding and interactions with the upper plate.
Cassini Observation of Relativistic Electron Butterfly Distributions in Saturn’s Inner Radiation Belts: Evidence for Acceleration by Local Processes
Authors: Yuan C.‐J. , Roussos E. , Wei Y. , Krupp N. , Sun Y. X. , Hao Y. X. 
Published: June 2021

AbstractThe morphology of electron pitch angle distributions (PADs) helps to identify dynamic processes in Saturn’s magnetosphere. Previous studies demonstrated convective transport being important for relativistic electron acceleration at L > 4 in the inner magnetosphere, whereas closer to Saturn the situation is not as well established. We have investigated the PADs of relativistic electrons throughout radiation belts, using 13‐years measurements from Cassini spacecraft. Our results show that at 3.5 < L < 6, the PADs peak near 90°. However, at 2.5 < L < 3.5, the PADs transform to butterfly distributions, dominating over an energy range of one order of magnitude, from 800 keV to >7 MeV. These results suggest that convective transport continues to govern down to L = 3.5. For even smaller L‐shells, the independence of butterfly PADs from energy suggests that the acceleration by resonant interactions of electrons with waves likely serves as an additional key mechanism regulating the dynamics in the core region of radiation belts.
Estimating Dissipation Rates Associated With Double Diffusion
Authors: Middleton L. , Fine E. C. , MacKinnon J. A. , Alford M. H. , Taylor J. R. 
Published: June 2021

AbstractDouble diffusion refers to a variety of turbulent processes in which potential energy is released into kinetic energy, made possible in the ocean by the difference in molecular diffusivities between salinity and temperature. Here, we present a new method for estimating the kinetic energy dissipation rates forced by double‐diffusive convection using temperature and salinity data alone. The method estimates the up‐gradient diapycnal buoyancy flux associated with double diffusion, which is hypothesized to balance the dissipation rate. To calculate the temperature and salinity gradients on small scales we apply a canonical scaling for compensated thermohaline variance (or ‘spice’) on sub‐measurement scales with a fixed buoyancy gradient. Our predicted dissipation rates compare favorably with microstructure measurements collected in the Chukchi Sea. Fine et al. (2018), https://doi.org/10.1175/jpo-d-18-0028.1, showed that dissipation rates provide good estimates for heat fluxes in this region. Finally, we show the method maintains predictive skill when applied to a sub‐sampling of the Conductivity, Temperature, Depth (CTD) data.
Contributions of Altimetry and Argo to Non‐Closure of the Global Mean Sea Level Budget Since 2016
Authors: Barnoud Anne , Pfeffer Julia , Guérou Adrien , Frery Marie‐Laure , Siméon Mathilde , Cazenave Anny , Chen Jianli , Llovel William , Thierry Virginie , Legeais Jean‐François , Ablain Michaël 
Published: June 2021

AbstractOver 1993–2016, studies have shown that the observed global mean sea level (GMSL) budget is closed within the current data uncertainties. However, non‐closure of the budget was recently reported when using Jason‐3, Argo and GRACE/GRACE Follow‐On data after 2016. This non‐closure may result from errors in the data sets used to estimate the GMSL and its components. Here, we investigate possible sources of errors affecting Jason‐3 and Argo data. Comparisons of Jason‐3 GMSL trends with other altimetry missions show good agreement within 0.4 mm/yr over 2016–present. Besides, the wet tropospheric correction uncertainty from the Jason‐3 radiometer contributes to up to 0.2 mm/yr. Therefore, altimetry alone cannot explain the misfit in the GMSL budget observed after 2016. Argo‐based salinity products display strong discrepancies since 2016, attributed to instrumental problems and data editing issues. Reassessment of the sea level budget with the thermosteric component provides about 40% improvement in the budget closure.
Lower Mantle Seismicity Following the 2015 Mw 7.9 Bonin Islands Deep‐Focus Earthquake
Authors: Kiser Eric , Kehoe Haiyang , Chen Min , Hughes Amanda 
Published: June 2021

AbstractDeep‐focus earthquakes provide insight into how subducting slabs deform over a range of spatial and temporal scales as they descend into the mantle. This study uses a 4D source imaging approach to determine centroid locations of the 2015 Mw 7.9 Bonin Islands deep‐focus earthquake and its aftershock sequence. Imaged sources of the mainshock show a complex rupture, but one that is compatible with a sub‐horizontal rupture plane. Previously undetected early aftershocks are imaged down to depths of approximately 750 km and represent the first reported earthquakes that initiate in the lower mantle. These events and a previously reported group of shallower distal aftershocks occur at the lower and upper boundaries of an imaged slab segment that deforms as it penetrates into the lower mantle. We hypothesize that mainshock failure allowed gravitational settling of the slab segment to occur which produced the distal aftershock sequences.
Ocean Circulation in the Challenger Deep Derived From Super‐Deep Underwater Glider Observation
Authors: Jiang Huichang , Xu Hongzhou , Vetter Philip A. , Xie Qiang , Yu Jiancheng , Shang Xuekun , Yu Liu 
Published: June 2021

AbstractOcean circulation in the Challenger Deep is rarely investigated due to sparse observations. Based on hydrographic data collected by two super‐deep Chinese “Sea‐Wing” gliders during September–October 2018, we analyzed water properties and ocean circulation structures in this trench. Results showed that the horizontal distribution of water properties is approximately a three layer structure, changing from a northeast‐southwest structure to a north‐south structure then to an east‐west structure as the depth increases from 3,000 to 7,000 m. This structure is a joint result of the water uplift, advection, and diffusion in the trench. The westward geostrophic flow, with 1.29 Sv (1 Sv = 106 m3 s−1) volume transport, dominates the deep layer of the Challenger Deep, gradually weakening with depth. The unexpectedly large volume transport, twice that of previous studies, might be due to temporal variations of LCDW (Lower Circumpolar Deep Water) intrusion from the Southern Ocean and different reference levels.
Electric Field Enlarges Raindrops Beneath Electrified Clouds: Observational Evidence
Authors: Mudiar Dipjyoti , Pawar S. D. , Gopalakrishnan V. , Williams Earle 
Published: June 2021

AbstractSimultaneous measurements of cloud electric field and raindrop size at the Earth's surface have been analyzed to investigate an anticipated relation between the two cloud parameters. A significant positive correlation is observed between the magnitude of the surface electric field and raindrop size supported by a theoretical framework advanced here. It is shown that in the presence of an electric field, raindrops increase their size through electrically induced collision and coalescence processes near the Earth's surface. This study also demonstrates that the presence of an electric field inside the cloud can enhance the rain intensity by influencing the growth rate of raindrops. This new insight may be useful for a proper understanding of the rain microphysics and for developing better numerical weather models for simulation and forecasting of heavy rainfall events associated with stronger in‐cloud electrical environments.