bluuebunny/crossref_metadata_2025 huggingface dataset:
Reward Value-Based Goal Selection for Agents’ Cooperative Route Learning Without Communication in Reward and Goal Dynamism
Authors: Uwano Fumito , Takadama Keiki
Published: May 2020

This paper proposes a goal selection method to operate agents get maximum reward values per time by noncommunicative learning. In particular, that method aims to enable agents to cooperate along to dynamism of reward values and goal locations. Adaptation against to these dynamisms can enable agents to learn cooperative actions along to changing transportation tasks and changing incomes/rewards because of transporting tasks for heavy/valuable and light/valueless items in a storehouse. Concretely, this paper extends the previous noncommunicative cooperative action learning method (Profit minimizing reinforcement learning with oblivion of memory: PMRL-OM) and sets the two unified conditions combined of the number of time steps and the rewards. One of the unified conditions is calculated the approximated number of time steps if the expected reward values are the same each other for all purposes, and the other is the minimum number of time steps divided by the reward value. The proposed method makes all agents learn to achieve the purposes in the order in which they have the minimum number of the condition values. After that, each agent learns cooperative policy by PMRL-OM as the previous method. This paper analyzes the unified conditions and derives that the condition calculating the approximated time steps can be combined both evaluations with almost same weight unlike the value the other condition, that is, the condition can help the agents to select the appropriate purposes among them with the small difference in terms of the two evaluations. This paper tests empirically the performances of PMRL-OM with the two conditions by comparing with the PMRL-OM in three cases of grid world problems whose goal locations and reward values are changed dynamically. The results of this derive that the unified conditions perform better than PMRL-OM without some conditions in grid world problems. In particular, it is clear that the condition calculating the approximated time step can direct the appropriate goals for the agents.
Tidal and Subtidal Variations in Water Level Produced by Ocean‐River Interactions in a Subtropical Estuary
Authors: Laurel‐Castillo J. A. , Valle‐Levinson A.
Published: May 2020

Near yearlong time series measurements of water level elevation from seven stations along the Suwannee River, Florida, were used to characterize, observationally and analytically, the propagation of tidal and subtidal signals along the estuary resulting from tide‐river interactions. Tidal amplitudes and phases were obtained from least squares fits to observed values and used to compare to an analytical model. Subtidal amplitude and phases were characterized by Hilbert empirical orthogonal functions (HEOFs), obtained through complex principal component analysis, and compared to an analytical solution. The landward attenuation of the tidal signal was replicated analytically. The subtidal signal (periods > tides) was also described analytically with an oceanic wave moving landward and a seaward river pulse. The subtidal analytical solution reproduced the competition between the landward and seaward waves and the zone where each wave dominated over the other. Depending on the phase of these landward and seaward subtidal waves, the resulting subtidal signal amplitude could either (a) attenuate landward to a certain location and then increase or (b) amplify landward up to a certain zone and then decrease.
Influence of Nonmigrating Tides and Geomagnetic Field Geometry on the Diurnal and Longitudinal Variations of the Equatorial Electrojet
Authors: Wang Hui , Zheng Zhichao , Zhang Kedeng , Wang Wenbin
Published: May 2020

In this study, equatorial electrojets (EEJs) simulated by the Thermosphere‐Ionosphere Electrodynamics General Circulation Model (TIE‐GCM) were compared with those observed by ground‐based magnetometers and the Challenging Minisatellite Payload (CHAMP) satellite. Simulations were performed with or without nonmigrating tidal forcing at the lower boundary and in the frame of the International Geomagnetic Reference Field (IGRF) or dipole field. The model forced by the nonmigrating tides could qualitatively reproduce the local time and longitudinal variation of an EEJ in the frame of the IGRF with accuracy. The tides were important in causing the later local time occurrence of the EEJ peak in the Peruvian sector, and they favored the occurrence of the morning counterelectrojet (CEJ) in the frame of the IGRF. The difference in the EEJ peak intensity between the Peruvian and Indian stations was enhanced due to the tidal effect. The net effect of the tides on the two‐station difference was almost doubled in the dipole field compared with that in the IGRF. The TIE‐GCM with a tidal input could reproduce a Wavenumber‐4 longitudinal structure of the noontime EEJ, but it underestimated the peak EEJ in the East Asia sector. The magnetically eastward electric field and the neutral zonal wind at noontime in the E region in the TIE‐GCM were both weak in the East Asia sector. This model‐data discrepancy was at least partly due to insufficient lower boundary forcing in this longitudinal sector.
Surface Wave Diffraction Pattern Recorded on AlpArray: Cameroon Volcanic Line Case Study
Authors: Kolínský Petr , Schneider Felix M. , Bokelmann Götz
Published: May 2020

Stripe‐like patterns of surface wave arrival angle deviations have been observed by several seismological studies around the world, but this phenomenon has not been explained so far. Here we test the hypothesis that systematic arrival angle deviations observed at the AlpArray broadband seismic network in Europe are interference patterns caused by diffraction of surface waves at single small‐scaled velocity anomalies. We use the observed pattern of Rayleigh waves from two earthquakes under the Southern Atlantic Ocean, and we fit this pattern with theoretical arrival angles derived by a simple modeling approach describing the interaction of a seismic wavefield with small anomalies. A grid search inversion scheme is implemented, which indicates that the anomaly is located in Central Africa, with its head under Cameroon. Moreover, the inversion enables the characterization of the anomaly: The anomaly is inferred to be between 320 and 420 km wide, matching in length the 2,500 km long upper mantle low‐velocity region under the volcano‐capped swells of the Cameroon volcanic line. We show that this approach can be generally used for studying the upper mantle anomalies worldwide.
Peak Ground Velocity Spatial Variability Revealed by Dense Seismic Array in Southern California
Authors: Johnson Christopher W. , Kilb Debi , Baltay Annemarie , Vernon Frank
Published: May 2020

Understanding and modeling variability of ground motion is essential for building accurate and precise ground motion prediction equations, which can net site‐specific characterization and reduced hazard levels. Here, we explore the spatial variability in peak ground velocity (PGV) at Sage Brush Flats along the San Jacinto Fault in Southern California. We use data from a dense array (0.6 × 0.6 km2, 1,108 geophones, station spacings 10–30 m) deployed in 2014 for ~1 month. These data offer an opportunity to study small‐scale variability in this region. We examine 38 earthquakes (2 ≤ ML ≤ 4.2) within 200 km of the array. Fault strands and a small basin impact the ground motions, producing PGV variations up to 22% of the mean and a 40% reduction in P and S wave near‐surface velocities. We find along‐fault rupture directivity, source, and path effects can increase PGVs by 167%. Surface PGV measurements exceed the colocated borehole station (depth at 148 m) PGV by factors of 3–10, confirming the impact on PGV from near‐surface fault structures, basins, topography, and amplifications from soft sediments. Consistently, we find high PGVs within the basin structure. A pair of colocated GaML2.6 events produce repeatable PGV values with similar spatial patterns. The average corner frequencies of these two events are 11–16 Hz, and viable measurements of stress drop can differ by 6.45 MPa. Within this small array, the PGV values are variable implying spatial extrapolation of PGV to regions of known faults and basins, even across a small area, should be done with caution.
The Formation of Hot Thermal Anomalies in Cold Subduction‐Influenced Regions of Earth's Lowermost Mantle
Authors: Li Mingming
Published: May 2020

The Earth's lowermost mantle is characterized by two large low shear velocity provinces (LLSVPs). The regions outside the LLSVPs have been suggested to be strongly influenced by subducted slabs and, therefore, much colder than the LLSVPs. However, localized low‐velocity seismic anomalies have been detected in the subduction‐influenced regions, whose origin remains unclear. Here, three‐dimensional geodynamic calculations are performed, and they show that linear, ridge‐like hot thermal anomalies, or thermal ridges, form in the relatively cold, downwelling regions of the lowermost mantle. Like the formation of Richter rolls due to sublithosphere small‐scale convection (SSC), the thermal ridges form as a result of SSC from the basal thermal boundary layer and they extend in directions parallel to the surrounding mantle flow. The formation of thermal ridges in subduction regions of the lowermost mantle is very sensitive to the thermal structures of the subducted materials, and thermal heterogeneities brought to the bottom of the mantle by subducting slabs greatly promote the formation of thermal ridges. The formation of thermal ridges is also facilitated by the increase of core‐mantle boundary heat flux and vigor of lowermost mantle convection. The thermal ridges may explain the low‐velocity seismic anomalies outside of the LLSVPs in the lowermost mantle. The results suggest that the relatively cold, subduction‐influenced regions of the Earth's lowermost mantle may contain localized hot anomalies.
Eddies in the North Greenland Sea and Fram Strait From Satellite Altimetry, SAR and High‐Resolution Model Data
Authors: Bashmachnikov Igor L. , Kozlov Igor E. , Petrenko Larisa A. , Glok Natalia I. , Wekerle Claudia
Published: May 2020

In this study, we investigate eddy dynamics in the northern Greenland Sea and the Fram Strait using AVISO altimetry, spaceborne synthetic aperture radar (SAR), and Finite Element Sea ice‐Ocean Model (FESOM) high‐resolution numerical model data. In the region, eddies are thought to play an important role in the redistribution of the warmer and saltier Atlantic Water between the Arctic Ocean and the areas of deep convection in the central Greenland Sea. We found that eddies detected in AVISO and in SAR form two complementary data sets of large mesoscale eddies (with typical radii of 30–50 km) and of small mesoscale/submesoscale eddies (with typical radii of 1–5 km and not exceeding 30 km), respectively. For large mesoscale eddies, the number of cyclones and anticyclones is approximately the same, while for submesoscale eddies, cyclones are strongly dominating. The limitations and possible biases in each of the data sets are discussed and cross‐validated against FESOM results. It is noted that the most energetic eddies are concentrated along the major currents and in the northern part of the region. Eddy translations follow the mean currents in their overall cyclonic circulation around the northern Greenland Sea. A convergence of the eddies toward the Nordbukta area is detected. On seasonal time scale, a higher number of more intense mesoscale eddies is observed during winter, associated with a quasi‐simultaneous intensification of the mean currents. Model results also show an increase in the number of small eddies in spring‐early summer attributed to the decay of large eddies, while in late autumn, the opposite tendency suggests eddy merger.
Reassessing the Quality of Sea‐Ice Deformation Estimates Derived From the RADARSAT Geophysical Processor System and Its Impact on the Spatiotemporal Scaling Statistics
Authors: Bouchat Amélie , Tremblay Bruno
Published: May 2020

We reassess the trajectory errors inherent to sea‐ice deformation estimates with a new propagation of uncertainty derivation and show that previous formulations applied to deformation estimates from the RADARSAT Geophysical Processor System (RGPS) are either too high due to incorrect assumptions or too low due to neglected terms in certain cases. We show that when the resulting signal‐to‐noise ratios are used to discriminate the deformation estimates based on their quality, as done for buoy records, the spatiotemporal scaling exponents for the mean total deformation rate increase, especially at smaller scale, such that a space‐time coupling of the scaling—which is otherwise absent—emerges from the RGPS deformation data set, in accord with previous analyses performed with buoy observations. We also show that the preprocessing method used to reduce the effects of irregular sampling of the Lagrangian deformation fields can significantly impact the value of the deformation statistics and could possibly explain part of previous discrepancies between deformation statistics obtained with buoy records and large‐scale synthetic aperture radar (SAR) imagery. Specifically, we show that spurious lines of deformation appear when interpolating RGPS trajectories that presenttemporal sampling inconsistencies. In the context of using observed sea‐ice deformation statistics to constrain and improve the performance of sea‐ice models, high confidence in the observed deformation field statistics is necessary. Using appropriate, well‐documented, methods to derive the set of statistics to be reproduced by models therefore becomes crucial.
Arctic Sea Ice Volume Export Through Fram Strait From 1992 to 2014
Authors: Spreen Gunnar , de Steur Laura , Divine Dmitry , Gerland Sebastian , Hansen Edmond , Kwok Ron
Published: May 2020

The Fram Strait sea ice volume export 1992–2014 is derived by combining sea ice thickness from upward looking sonars (ULS) with satellite observations of sea ice drift and area. Fram Strait is the main gate for sea ice export from the Arctic. The average yearly sea ice export is 2,400 ± 640 km3. The mean and modal ULS ice thickness in Fram Strait decreased by 15% and 21% per decade, respectively, during 1990–2014. Combined with sea ice drift and area this leads to a decrease of the Arctic sea ice volume export of 27 ± 2% per decade between 1992 and 2014. Thus, for the given time period, changes in sea ice export do not drive the sea ice volume decrease in the Arctic Basin. However, for individual years like 2007 and 2012 the ice export likely has contributed to the loss of summer sea ice. Combined with PIOMAS model simulation we estimate that 14% of the total Arctic sea ice volume is exported every year through Fram Strait. This fraction of the total sea ice volume exported per year does not show a trend because the Arctic Basin ice volume is decreasing at a similar rate as the Fram Strait ice volume export. Compared to ice velocities from Acoustic Doppler Current Profiler (ADCP) the satellite ice drift shows good correspondence in variability but a negative bias. Ice volume transport estimates presented here thus should be considered a conservative estimate. We show, however, that the transport estimates are not sensitive to the exact flux gate location.
Localization and Invigoration of Mei‐yu Front Rainfall due to Aerosol‐Cloud Interactions: A Preliminary Assessment Based on WRF Simulations and IMFRE 2018 Field Observations
Authors: Liu Lin , Cui Chunguang , Deng Yi , Zhou Zhimin , Hu Yang , Wang Bin , Ren Jing , Cai Zhaoxin , Bai Yongqing , Yang Junmei , Dong Xiquan
Published: May 2020

Aerosol‐cloud interactions remain a major source of uncertainty in our understanding and modeling of the Earth's hydrological cycle. Based upon a diagnostic and modeling analysis utilizing the latest field measurements from the Integrative Monsoon Frontal Rainfall Experiment (IMFRE) 2018, this paper reports the effects of aerosols on the cloud properties along the Mei‐yu front over the Middle Reaches of Yangtze River in China. Numerical experiments with the Weather Research and Forecasting (WRF) model suggest that increasing aerosol number concentration reduces surface precipitation by ~8.8% and delays the onset of rainfall by ~30 min. Furthermore, warm clouds are suppressed but the convective cores are slightly intensified. This corresponds to an overall aerosol effect of “localization and invigoration” of the Mei‐yu rainfall and thus an elevated probability of short‐term heavy rainfall. The signals of “convective invigoration” with a bulk scheme in this study are relatively weak compared to those simulated by bin microphysics. The increased aerosol concentration strengthens Mei‐yu front and changes local morphology of the front, consistent with earlier studies demonstrating positive effects of convective heating on the genesis and maintenance of Mei‐yu front via conditional instability of the second kind (CISK) and diabatic generation of potential vorticity. Also discussed are the uncertainties of bulk microphysics in simulating aerosol‐cloud interactions, which may shed light on the design of future field campaigns to further understand the impact of aerosol‐cloud interactions on weather and climate over China in boreal summer.
Cold Pool Responses to Changes in Soil Moisture
Authors: Drager Aryeh J. , Grant Leah D. , van den Heever Susan C.
Published: May 2020

This study examines the role of soil moisture in modulating convective cold pool properties in an idealized modeling framework that uses a cloud‐resolving model coupled to an interactive land surface model. Five high‐resolution simulations of tropical continental convection are conducted in which the initial soil moisture is varied. The hundreds of cold pools forming within each simulation are identified and composited across space and time using an objective cold pool identification algorithm. Several important findings emerge from this analysis. Lower soil moisture results in greater daytime heating of the surface, which produces a deeper, drier subcloud layer. As a result, latent cooling through the evaporation of precipitation is enhanced, and cold pools are stronger and deeper. Increased propagation speed, combined with wider rain shafts, results in wider cold pools. Finally, the rings of enhanced water vapor that surround each cold pool when soil is wet disappear when the soil moisture is reduced, due to the suppression of surface latent heat fluxes. Instead, short‐lived “puddles” of enhanced water vapor permeate the cold pools. The results are nonlinear in that the properties of the cold pools in the two driest‐soil simulations depart substantially from the cold pool properties in the three simulations initialized with wetter soil. The dividing line between the resulting wet‐soil and dry‐soil regimes is the permanent wilting point. Below the permanent wilting point, transpiration is subdued due to a sharp increase in water stress. These results emphasize the role of land surface‐boundary layer‐cloud interactions in modulating cold pool properties.
Temperature Profiles From Two Close Lidars and a Satellite to Infer the Structure of a Dominant Gravity Wave
Authors: Alexander P. , de la Torre A. , Kaifler N. , Kaifler B. , Salvador J. , Llamedo P. , Hierro R. , Hormaechea J. L.
Published: May 2020

Gravity waves (GW) are a crucial coupling mechanism for the exchange of energy and momentum flux (MF) between the lower, middle, and upper layers of the atmosphere. Among the remote instruments used to study them, there has been a continuous increment in the last years in the installation and use of lidars (light detection and ranging) all over the globe. Two of them, which are only night operating, are located in Río Gallegos (−69.3° W, −51.6° S) and Río Grande (−67.8° W, −53.8° S), in the neighborhood of the austral tip of South America. This is a well‐known GW hot spot from late autumn to early spring. Neither the source for this intense activity nor the extent of its effects have been yet fully elucidated. In the last years, different methods that combine diverse retrieval techniques have been presented in order to describe the three‐dimensional (3‐D) structure of observed GW, their propagation direction, their energy, and the MF that they carry. Assuming the presence of a dominant GW in the covered region, we develop here a technique that uses the temperature profiles from two simultaneously working close lidars to infer the vertical wavelength, ground‐based frequency, and horizontal wavelength along the direction joining both instruments. If in addition within the time and spatial frame of both lidars there is also a retrieval from a satellite like SABER (Sounding of the Atmosphere using Broadband Emission Radiometry), then we show that it is possible to infer also the second horizontal wavelength and therefore reproduce the full 3‐D GW structure. Our method becomes verified with an example that includes tests that corroborate that both lidars and the satellite are sampling the same GW. The improvement of the Río Gallegos lidar performance could lead in the future to the observation of a wealth of cases during the GW high season. Between 8 and 14 hr (depending on the month) of continuous nighttime data could be obtained in the stratosphere and mesosphere in simultaneous soundings from both ground‐based lidars.
A Whole World View
Authors: Goss Heather
Published: May 2020

Scientists are dedicated to understanding the complexities of the Earth’s carbon cycle—and how our actions can throw it off.
Dynamics of Large‐Scale Solar‐Wind Streams Obtained by the Double Superposed Epoch Analysis: 4. Helium Abundance
Authors: Yermolaev Y. I. , Lodkina I. G. , Yermolaev M. Y. , Riazantseva M. O. , Rakhmanova L. S. , Borodkova N. L. , Shugay Y. S. , Slemzin V. A. , Veselovsky I. S. , Rodkin D. G.
Published: May 2020

This work is a continuation of our previous articles (Yermolaev et al., 2015, https://doi.org/10.1002/2015JA021274; 2017, https://doi.org/10.1007/s11207-017-1205-1; 2018, https://doi.org/10.1007/s11207-018-1310-9), which describe the average temporal profiles of interplanetary plasma and field parameters in large‐scale solar‐wind (SW) streams: corotating interaction regions (CIRs), interplanetary coronal mass ejections (ICMEs including both magnetic clouds (MCs), and ejecta), and sheaths as well as interplanetary shocks (ISs). In this work, we analyze the average profile of helium abundance, Nα/Np, for 1976–2016. Our results confirm the main results that were obtained in earlier studies: Nα/Np is higher in quasi‐stationary fast streams than in slow ones; it slowly changes in compression regions CIRs and sheaths from values in undisturbed SW to values in the corresponding fast stream type pushing like a piston, in high‐speed stream (HSS) flow for CIRs, or in ICME for sheaths; in ejecta, it is close to the abundance observed in undisturbed streams, and it is maximal in MCs. For the first time, the results show that Nα/Np correlates with the proton β‐parameter in compression regions CIRs and sheath and anticorrelates in ICMEs. The Nα/Np versus β dependence is stronger in MCs than in ejecta and may be used as an indicator of conditions at the place on the Sun where CMEs are formed.
Reconstruction of Electron and Ion Distribution Functions in a Magnetotail Reconnection Diffusion Region
Authors: Ng Jonathan , Chen Li‐Jen , Hakim Ammar , Bhattacharjee Amitava
Published: May 2020

In the diffusion region of magnetotail reconnection, particle distributions are highly structured, exhibiting triangular shapes and multiple striations that deviate dramatically from the Maxwellian distribution. Fully kinetic simulations have been demonstrated to be capable of producing the essential structures of the observed distribution functions, yet are computationally not feasible for 3D global simulations. The fluid models used for large‐scale simulations, on the other hand, do not have the kinetic physics necessary for describing reconnection accurately. Our study aims to bridge fully kinetic and fluid simulations by quantifying the information required to capture the non‐Maxwellian features in the distributions underlying the closures used in the fluid code. We compare the results of fully kinetic simulations with observed electron velocity distributions in a magnetotail reconnection diffusion region and use the maximum entropy model to reconstruct electron and ion distributions using various numbers of moments obtained from the simulation. Our results indicate that using only local moments, the maximum entropy model can reproduce many of the features of the distributions: (1) the electron outflow distribution with a tilted triangular structure is reproduced with 21 or more moments in agreement with Ng et al. (2018, https://doi.org/10.1063/1.5041758) and (2) counterstreaming distributions can be captured with the 35‐moment model when the separation in velocity space between the populations is large.
Mixed‐Mode Formation of Amorphous Materials in the Creeping Zone of the Chihshang Fault, Taiwan, and Implications for Deformation Style
Authors: Wu Wen‐Jie , Kuo Li‐Wei , Ku Ching‐Shun , Chiang Ching‐Yu , Sheu Hwo‐Shuenn , Aprilniadi Tyas Dwi , Dong Jia‐Jyun
Published: May 2020

Experimental results demonstrate that amorphous materials can be generated by frictional sliding at a wide range of conditions and that once formed the frictional strength of the fault is reduced. Nevertheless, amorphous materials have not been described in many natural faults, and their importance in natural systems is not well understood. We have identified amorphous materials within a 3‐mm‐thick slip zone (i.e., narrow band) in the Chihshang Fault, Taiwan, as well as within a submicrometer thick band in a distributed network of scaly clays. The scaly clays resemble those developed in other faults that demonstrably accommodated slow creep, and they also impart very low permeability implying that fluid‐related alteration (which could result in amorphization) will be inefficient. For this reason, and because of its throughgoing nature and position within a deforming zone, we infer a shear‐related origin for the amorphous materials. Therefore, amorphous materials can be observed in near‐surface environments because they have been formed during recent deformation under limited fluid‐circulation circumstances. The narrow slip zone containing amorphous materials is throughgoing and is interpreted to have acted as a frictional interface that accommodated brittle deformation at the macroscopic scale, whereas the surrounding mélange accommodated distributed “ductile” shear. The formation of amorphous materials therefore typifies the “mixed‐mode” style of deformation in this creeping fault zone.
Atmospheric Drivers of Melt on Larsen C Ice Shelf: Surface Energy Budget Regimes and the Impact of Foehn
Authors: Elvidge Andrew D. , Kuipers Munneke Peter , King John C. , Renfrew Ian A. , Gilbert Ella
Published: May 2020

Recent ice shelf retreat on the east coast of the Antarctic Peninsula has been principally attributed to atmospherically driven melt. However, previous studies on the largest of these ice shelves—Larsen C—have struggled to reconcile atmospheric forcing with observed melt. This study provides the first comprehensive quantification and explanation of the atmospheric drivers of melt across Larsen C, using 31‐months' worth of observations from Cabinet Inlet, a 6‐month, high‐resolution atmospheric model simulation and a novel approach to ascertain the surface energy budget (SEB) regime. The dominant meteorological controls on melt are shown to be the occurrence, strength, and warmth of mountain winds called foehn. At Cabinet Inlet, foehn occurs 15% of the time and causes 45% of melt. The primary effect of foehn on the SEB is elevated turbulent heat fluxes. Under typical, warm foehn conditions, this means elevated surface heating and melting, the intensity of which increases as foehn wind speed increases. Less commonly—due to cooler‐than‐normal foehn winds and/or radiatively warmed ice—the relationship between wind speed and net surface heat flux reverses. This explains the seemingly contradictory results of previous studies. In the model, spatial variability in cumulative melt across Larsen C is largely explained by foehn, with melt maxima in inlets reflecting maxima in foehn wind strength. However, most accumulated melt (58%) occurs due to solar radiation in the absence of foehn. A broad north‐south gradient in melt is explained by the combined influence of foehn and non‐foehn conditions.
Diurnal Cycle of Precipitation Over the Maritime Continent Under Modulation of MJO: Perspectives From Cloud‐Permitting Scale Simulations
Authors: Wei Yuntao , Pu Zhaoxia , Zhang Chidong
Published: May 2020

Cloud‐permitting scale (3 km) simulations are made to investigate the diurnal cycle of precipitation (DCP) over the Indo‐Pacific Maritime Continent under the modulation of the Madden‐Julian Oscillation (MJO), focusing on January–February 2018 during the Years of the Maritime Continent (YMC). Comparisons with satellite precipitation and global reanalysis products show that the simulations reasonably capture main features of diurnal wind and precipitation. The MJO modulates the amplitude, timing, and propagation of the DCP through affecting both large‐scale and local circulation and convection. Under local suppressed conditions, much strengthened sea/valley breezes are generally responsible for the enhanced and earlier‐triggered (2‐ to 3‐hr lead) DCP over land. Meanwhile, stronger cooling induced by enhanced stratiform rainfall excites well‐developed gravity waves spreading outward and upward, accompanied by continuous decreases in low‐level temperature and amplified land breezes, which cause stronger and further offshore‐propagating DCP. The opposite is true under local active conditions. Modulated by the passing of MJO, the enhanced DCP also displays a systematic shift from the west to the east coasts of large islands, forming a unique dipolar structure in the anomalous island DCP. The DCP exhibits island‐dependent characteristics: With topographical elevation, the triggering mechanism of island convection transforms from later penetrating sea breeze fronts over mountain foothills to early‐excited valley winds over mountain tops. Steep topography also supports stronger intraseasonal variations of the DCP, which can be well explained by regional variations in land‐sea/mountain‐valley breezes, terrain lifting, and ambient wind‐induced advective and vertical wind shear effects.
Me, myself, bye: regional alterations in glutamate and the experience of ego dissolution with psilocybin
Authors: Mason N. L. , Kuypers K. P. C. , Müller F. , Reckweg J. , Tse D. H. Y. , Toennes S. W. , Hutten N. R. P. W. , Jansen J. F. A. , Stiers P. , Feilding A. , Ramaekers J. G.
Published: May 2020

There is growing interest in the therapeutic utility of psychedelic substances, like psilocybin, for disorders characterized by distortions of the self-experience, like depression. Accumulating preclinical evidence emphasizes the role of the glutamate system in the acute action of the drug on brain and behavior; however this has never been tested in humans. Following a double-blind, placebo-controlled, parallel group design, we utilized an ultra-high field multimodal brain imaging approach and demonstrated that psilocybin (0.17 mg/kg) induced region-dependent alterations in glutamate, which predicted distortions in the subjective experience of one’s self (ego dissolution). Whereas higher levels of medial prefrontal cortical glutamate were associated with negatively experienced ego dissolution, lower levels in hippocampal glutamate were associated with positively experienced ego dissolution. Such findings provide further insights into the underlying neurobiological mechanisms of the psychedelic, as well as the baseline, state. Importantly, they may also provide a neurochemical basis for therapeutic effects as witnessed in ongoing clinical trials.
Ruxolitinib plus extracorporeal photopheresis (ECP) for steroid refractory acute graft-versus-host disease of lower GI-tract after allogeneic stem cell transplantation leads to increased regulatory T cell level
Authors: Modemann Franziska , Ayuk Francis , Wolschke Christine , Christopeit Maximilian , Janson Dietlinde , von Pein Ute-Marie , Kröger Nicolaus
Published: May 2020

Acute graft-versus-host disease (aGVHD) is a serious complication after stem cell transplantation and is associated with high non-relapse mortality. If steroid treatment as first-line therapeutic approach fails, treatment options are limited. In retrospective studies, ruxolitinib, a selective Janus kinase 1/2 inhibitor as well as extracorporeal photopheresis (ECP) could show high efficacy in treatment of steroid refractory acute and chronic GVHD. Here, we report single-center experience of combining JAK-inhibitor treatment with ECP in 18 patients with severe steroid refractory aGVHD of lower GI-tract. The treatment was well tolerated and no severe cytopenia (grade IV) occurred, in three patients grade III cytopenia could be observed. Response was complete or partial in 44% and 11%, respectively, resulting in an estimated 2 year overall survival of 56%. Steroids were tapered rapidly with a median time of 2 days for halving of dosage avoiding additional steroid-associated side effects. Under treatment with ruxolitinib and ECP, an increased level of regulatory T cells could be observed elucidating direct effects of this treatment on immune response.
LncRNA SNHG17 aggravated prostate cancer progression through regulating its homolog SNORA71B via a positive feedback loop
Authors: Wu Gaoliang , Hao Chao , Qi Xueliang , Nie Jianqiang , Zhou Weimin , Huang Ji , He Qiuming
Published: May 2020

Prostate cancer (PC) is a prevalent male malignancy with high occurrence rate. Recent studies have showed that small nucleolar host genes (SNHGs) and their homolog small nucleolar RNAs (snoRNAs) elicit regulatory functions in carcinogenesis. Present study aimed to investigate the role of SNHG17 and its homolog SNORA71B in PC. Function of SNHG17 and SNORA71B in PC is detected by CCK-8, colony formation, flow cytometry analysis of apoptosis, and transwell migration assay. The mechanism whereby SNHG17 regulated SNORA71B was detected by RIP, pulldown, ChIP, and luciferase reporter assays. Results depicted that transcript 6 of SNHG17 and SNORA71B were upregulated in PC. Knockdown of SNHG17 or SNORA71B weakened proliferation, invasion, migration, and epithelial-to-mesenchymal transition (EMT) and strengthened apoptosis. Mechanistically, SNHG17 and SNORA71B were transcriptionally activated by signal transducer and activator of transcription 5A (STAT5A). SNHG17 positively regulated SNORA71B in PC cell lines and other cell lines. SNHG17 sponged miR-339-5p to upregulate STAT5A and therefore to cause transactivation of SNORA71B. Rescue experiments delineated that SNORA71B was required for the regulation of SNHG17 on PC. Moreover, SNHG17 silence hindered tumorigenesis of PC in vivo. In conclusion, current study first revealed that lncRNA SNHG17 aggravated prostate cancer progression through regulating its homolog SNORA71B via a positive feedback loop, which might do help to the pursuit of better PC treatment.
Splicing- and demethylase-independent functions of LSD1 in zebrafish primitive hematopoiesis
Authors: Tamaoki Junya , Takeuchi Miki , Abe Ryo , Kaneko Hiroshi , Wada Taeko , Hino Shinjiro , Nakao Mitsuyoshi , Furukawa Yusuke , Kobayashi Makoto
Published: May 2020

LSD1/KDM1A is a widely conserved lysine-specific demethylase that removes methyl groups from methylated proteins, mainly histone H3. We previously isolated the zebrafish LSD1 gene and demonstrated that it is required for primitive hematopoiesis. Recently, a neuron-specific splicing variant of LSD1 was found in mammals and its specific functions and substrate specificities were reported. To our surprise, zebrafish LSD1 cDNA, which we previously analyzed, was corresponded to the neuron-specific variant in mammals. In this study, we investigated the structures and expression of LSD1 splicing variants in zebrafish and found all 4 types of LSD1 isoforms: LSD1, LSD1+2al, LSD1+8al and LSD1+2al8al. Interestingly, LSD1+8al/LSD1+2al8al, which correspond to mammalian neuron-specific variants, expressed ubiquitously in zebrafish. We also performed phenotypic rescue experiments of a zebrafish LSD1 mutant (kdm1ait627) using human and zebrafish LSD1 variants to identify which variant is involved in primitive hematopoiesis. Unexpectedly, the overexpression of all types of human and zebrafish variants was able to rescue the hematopoietic phenotypes in LSD1 mutants. Furthermore, enzymatic-deficient LSD1K661A (human) and K638A (zebrafish) were also able to rescue the mutant phenotypes. These results suggest that the LSD1 functions in zebrafish primitive hematopoiesis are free from any splicing-dependent regulation or demethylation reaction.
Robotic sheath-flow probe electrospray ionization/mass spectrometry (sfPESI/MS): development of a touch sensor for samples in a multiwell plastic plate
Authors: Hiraoka Kenzo , Ariyada Osamu , Sekine Ryo , Ninomiya Satoshi , Usmanov Dilshadbek T. , Wada Hiroshi , Nonami Hiroshi
Published: May 2020

In the previous work, sheath-flow probe electrospray ionization (sfPESI) equipped with a touch sensor was developed for conducting samples.
Nanoarchitectured reduced graphene oxide composite C2N materials as flow electrodes to optimize desalination performance
Authors: Li Danping , Ning Xun-An , Li Yang , Zhang Jianpei
Published: May 2020

Low contents of rGO can form a conductive network, increase active particle utilization, and greatly promote electroadsorption.
Highly efficient solar anti-icing/deicing via a hierarchical structured surface
Authors: Wu Chenyang , Geng Hongya , Tan Sicong , Lv Jianyong , Wang Haiqiao , He Zhiyuan , Wang Jianjun
Published: May 2020

Efficient solar anti-icing/deicing polydimethylsiloxane/reduced graphene oxide (HPG) films with superior sunlight harvesting performances and high deicing efficiencies have been reported here.
2,2′-Dipyridyl diselenide (Py2Se2) induces G1 arrest and apoptosis in human lung carcinoma (A549) cells through ROS scavenging and reductive stress
Authors: Gandhi V V , Phadnis Prasad P , Kunwar A
Published: May 2020

Organo-diselenides are well documented for pro-oxidant effects in tumor cells. However, the present study demonstrated that 2,2′-dipyridyl diselenide (Py2Se2) induced cytotoxicity in human non-small cell lung carcinoma (A549) cells through reductive stress marked by a significant decrease in the basal level of reactive oxygen species and a concurrent decrease in the ratio of oxidised (GSSG) and reduced (GSH) glutathione. The IC50 (concentration inducing 50% cytotoxicity) of Py2Se2 in A549 and human normal lung fibroblast (WI38) cells was ∼8.5 μM and ∼5.5 μM, respectively, indicating that Py2Se2 did not exhibit selective toxicity towards cancer cells. Cell free studies indicated that Py2Se2 acted as a substrate of thioredoxin reductase (TrxR) and accordingly it was proposed that TrxR mediated reduction of Py2Se2 within cells might be generating intermediates leading to a reductive environment. Despite generating a reducing environment, Py2Se2 caused significant DNA damage, G1 phase arrest and apoptosis. The mechanistic investigation revealed that Py2Se2 induced G1 arrest was mediated through up-regulation of p21 transcript in a p53 independent manner. Further, the apoptotic effect of Py2Se2 was associated with the increase in the levels of unfolded protein response markers like BiP and CHOP, mitochondrial permeability (JC1) and apoptotic markers such as cleaved caspase-3 and poly (ADP-ribose) polymerase. Finally, pre-treatment with N-acetylcysteine (a stimulator of GSH biosynthesis) or l-buthionine sulfoximine (an inhibitor of GSH biosynthesis) increased and decreased the Py2Se2 mediated apoptosis, respectively. This confirmed that the cytotoxicity of Py2Se2 in A549 cells was triggered through reductive stress.
Ultrathin RuRh@(RuRh)O2core@shell nanosheets as stable oxygen evolution electrocatalysts
Authors: Wang Kai , Huang Bolong , Zhang Weiyu , Lv Fan , Xing Yi , Zhang Wenshu , Zhou Jinhui , Yang Wenxiu , Lin Fangxu , Zhou Peng , Li Mingqiang , Gao Peng , Guo Shaojun
Published: May 2020

We report a novel architecture of ultrathin RuRh@(RuRh)O2core/shell nanosheets with a core of ultrathin metallic RuRh nanosheets and a shell of (RuRh)O2oxides as a superb electrocatalyst toward the oxgen evolution reaction (OER), better than most of the state-of-the-art Ru-based or Ir-based electrocatalysts. Moreover, the RuRh@(RuRh)O2core/shell nanosheets exhibit good durability because the (RuRh)O2oxide shell protects the normally labile RuRh NS core against dissolution during the OER process.
Sulfonated glycosaminoglycan bioinspired carbon dots for effective cellular labelling and promotion of the differentiation of mesenchymal stem cells
Authors: Cai Huijuan , Ma Jiayun , Xu Xinyuan , Chu Hetao , Zhang Dongyue , Li Jianshu
Published: May 2020

Fluorescent carbon dots (CDs) bioinspired from sulfonated glycosaminoglycan were elaborately designed and fabricated via a facile hydrothermal synthesis, effectively achieving the cellular imaging and regulating behaviors of mesenchymal stem cells.
An inorganic stable Sn-based perovskite film with regulated nucleation for solar cell application
Authors: Li Junming , Huang Jianting , Zhao Andi , Li Yafeng , Wei Mingdeng
Published: May 2020

Vacuum flash-assisted solution processing method was used to prepare CsSnI3 PSCs and a PCE of 3.8% was achieved.
Self-consistent 3D radiative magnetohydrodynamic simulations of coronal rain formation and evolution
Authors: Kohutova P. , Antolin P. , Popovas A. , Szydlarski M. , Hansteen V. H.
Published: May 2020

Context. Coronal rain consists of cool and dense plasma condensations formed in coronal loops as a result of thermal instability.

Aims. Previous numerical simulations of thermal instability and coronal rain formation have relied on the practice of artificially adding a coronal heating term to the energy equation. To reproduce large-scale characteristics of the corona, the use of more realistic coronal heating prescription is necessary.

Methods. We analysed coronal rain formation and evolution in a three-dimensional radiative magnetohydrodynamic simulation spanning from convection zone to corona which is self-consistently heated by magnetic field braiding as a result of convective motions.

Results. We investigate the spatial and temporal evolution of energy dissipation along coronal loops which become thermally unstable. Ohmic dissipation in the model leads to the heating events capable of inducing sufficient chromospheric evaporation into the loop to trigger thermal instability and condensation formation. The cooling of the thermally unstable plasma occurs on timescales that are comparable to the duration of the individual impulsive heating events. The impulsive heating has sufficient duration to trigger thermal instability in the loop but does not last long enough to lead to coronal rain limit cycles. We show that condensations can either survive and fall into the chromosphere or be destroyed by strong bursts of Joule heating associated with a magnetic reconnection events. In addition, we find that condensations can also form along open magnetic field lines.

Conclusions. We modelled, for the first time, coronal rain formation in a self-consistent 3D radiative magnetohydrodynamic simulation, in which the heating occurs mainly through the braiding and subsequent Ohmic dissipation of the magnetic field. The heating is stratified enough and lasts for long enough along specific field lines to produce the necessary chromospheric evaporation that triggers thermal instability in the corona.
Long-period Ap stars discovered with TESS data
Authors: Mathys G. , Kurtz D. W. , Holdsworth D. L.
Published: May 2020

The TESS space mission’s primary goal is to search for exoplanets around bright, nearby stars. Because of the high-precision photometry required for the main mission, it is also producing superb data for asteroseismology, eclipsing binary stars, gyrochronology, indeed any field of stellar astronomy where the data are variable light curves. In this work we show that the TESS data are excellent for astrophysical inference from peculiar stars that show no variability. Ap stars have the strongest magnetic fields of any main-sequence star. Some Ap stars have also been shown to have rotation periods of months, years, decades, and even centuries. The astrophysical cause of their slow rotation – the braking mechanism – is not known with certainty. These stars are rare: there are currently about three dozen with known periods. Magnetic Ap stars have long-lived spots that allow precise determination of their rotation periods. We argue and show that most Ap stars with TESS data that show no low-frequency variability must have rotation periods longer than, at least, a TESS sector of 27 d. From this we find 60 Ap stars in the southern ecliptic hemisphere TESS data with no rotational variability, of which at most a few can be pole-on, and six likely have nearly aligned magnetic and rotation axes. Of the other 54, 31 were previously known to have long rotation periods or very low projected equatorial velocities, which proves our technique; 23 are new discoveries. These are now prime targets for long-term magnetic studies. We also find that 12 of the 54 (22%) long-period Ap stars are roAp stars, versus only 3% (29 out of 960) of the other Ap stars studied with TESS in Sectors 1–13, showing that the roAp phenomenon is correlated with rotation, although this correlation is not necessarily causal. In addition to probing rotation in Ap stars, these constant stars are also excellent targets to characterise the instrumental behaviour of the TESS cameras, as well as for the CHEOPS and PLATO missions. This work demonstrates astrophysical inference from nonvariable stars – we can get “something for nothing”.
Is Group B Streptococcus Colonization Associated with Maternal Peripartum Infection in an Era of Routine Prophylaxis?
Authors: Venkatesh Kartik K. , Vladutiu Catherine J. , Glover Angelica V. , Strauss Robert A. , Stringer Jeffrey S.A. , Stamilio David M. , Hughes Brenna , Dotters-Katz Sarah
Published: May 2020

Objective This study aimed to assess whether colonization with group B streptococcus (GBS) is associated with maternal peripartum infection in an era of routine prophylaxis.

Study Design This study presented a secondary analysis of women delivering ≥37 weeks who underwent a trial of labor from the U.S. Consortium on Safe Labor (CSL) study. The exposure was maternal GBS colonization and the outcome was a diagnosis of chorioamnionitis, and secondarily, analyses were restricted to deliveries not admitted in labor and measures of postpartum infection (postpartum fever, endometritis, and surgical site infection). Logistic regression with generalized estimating equations was used accounting for within-woman correlations. Models adjusted for maternal age, parity, race, prepregnancy body mass index, pregestational diabetes, insurance status, study site/region, year of delivery, number of vaginal exams from admission to delivery, and time (in hours) from admission to delivery.

Results Among 170,804 assessed women, 33,877 (19.8%) were colonized with GBS and 5,172 (3.0%) were diagnosed with chorioamnionitis. While the frequency of GBS colonization did not vary by chorioamnionitis status (3.0% in both groups), in multivariable analyses, GBS colonization was associated with slightly lower odds of chorioamnionitis (adjusted odds ratio [AOR]: 0.89; 95% confidence interval [CI]: 0.83–0.96). In secondary analyses, this association held regardless of spontaneous labor on admission; and the odds of postpartum infectious outcomes were not higher with GBS colonization.

Conclusion In contrast to historical data, GBS colonization was associated with lower odds of chorioamnionitis in an era of routine GBS screening and prophylaxis.

Key Points