bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multisatellite MMS Analysis of Electron Holes in the Earth's Magnetotail: Origin, Properties, Velocity Gap, and Transverse Instability
Authors: Lotekar A. , Vasko I. Y. , Mozer F. S. , Hutchinson I. , Artemyev A. V. , Bale S. D. , Bonnell J. W. , Ergun R. , Giles B. , Khotyaintsev Yu. V. , Lindqvist P.‐A. , Russell C. T. , Strangeway R. 
Published: August 2020

AbstractWe present a statistical analysis of more than 2,400 electrostatic solitary waves interpreted as electron holes (EH) measured aboard at least three Magnetospheric Multiscale (MMS) spacecraft in the Earth's magnetotail. The velocities of EHs are estimated using the multispacecraft interferometry. The EH velocities in the plasma rest frame are in the range from just a few km/s, which is much smaller than ion thermal velocity VTi, up to 20,000 km/s, which is comparable to electron thermal velocity VTe. We argue that fast EHs with velocities larger than about 0.1VTe are produced by bump‐on‐tail instabilities, while slow EHs with velocities below about 0.05VTe can be produced by warm bistream and, probably, Buneman‐type instabilities. We show that typically fast and slow EHs do not coexist, indicating that the instabilities producing EHs of different types operate independently. We have identified a gap in the distribution of EH velocities between VTi and 2VTi, which is considered to be the evidence for self‐acceleration (Zhou & Hutchinson, 2018) or ion Landau damping of EHs. Parallel spatial scales and amplitudes of EHs are typically between λD and 10 λD and between 10−3 Te and 0.1 Te, respectively. We show that electrostatic potential amplitudes of EHs are below the threshold of the transverse instability and highly likely restricted by the nonlinear saturation criterion of electron streaming instabilities seeding electron hole formation:
, where ϖ = min(γ, 1.5 ωce), where γ is the increment of instabilities seeding EH formation, while ωce is electron cyclotron frequency. The implications of the presented results are discussed.
Evolution of the Geomagnetic Daily Variation at Tatuoca, Brazil, From 1957 to 2019: A Transition From Sq to EEJ
Authors: Soares G. , Yamazaki Y. , Cnossen I. , Matzka J. , Pinheiro K. J. , Morschhauser A. , Alken P. , Stolle C. 
Published: August 2020

AbstractThe magnetic equator in the Brazilian region has moved over 1,100 km northward since 1957, passing the geomagnetic observatory Tatuoca (TTB), in northern Brazil, around 2013. We recovered and processed TTB hourly mean values of the geomagnetic field horizontal (H) component from 1957 until 2019, allowing the investigation of long‐term changes in the daily variation due to the influence of secular variation, solar activity, season, and lunar phase. The H day‐to‐day variability and the occurrence of the counter electrojet at TTB were also investigated. Until the 1990s, ionospheric solar quiet currents dominated the quiet‐time daily variation at TTB. After 2000, the magnitude of the daily variation became appreciably greater due to the equatorial electrojet (EEJ) contribution. The H seasonal and day‐to‐day variability increased as the magnetic equator approached, but their amplitudes normalized to the average daily variation remained at similar levels. Meanwhile, the amplitude of the lunar variation, normalized in the same way, increased from 5% to 12%. Within the EEJ region, the occurrence rate of the morning counter electrojet (MCEJ) increased with proximity to the magnetic equator, while the afternoon counter electrojet (ACEJ) did not. EEJ currents derived from CHAMP and Swarm satellite data revealed that the MCEJ rate varies with magnetic latitude within the EEJ region while the ACEJ rate is largely constant. Simulations with the Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model based on different geomagnetic main field configurations suggest that long‐term changes in the geomagnetic daily variation at TTB can be attributed to the main field secular variation.
First Zonal Drift Velocity Measurement of Equatorial Plasma Bubbles (EPBs) From a Geostationary Orbit Using GOLD Data
Authors: Karan Deepak K. , Daniell Robert E. , England Scott L. , Martinis Carlos R. , Eastes Richard W. , Burns Alan G. , McClintock William E. 
Published: August 2020

AbstractThe National Aeronautics and Space Administration (NASA) Global‐scale Observations of the Limb and Disk (GOLD) satellite takes far‐ultraviolet images of the Earth from geostationary orbit. GOLD observes the complete structure of equatorial plasma bubbles (EPBs). Since there are repeated observations of the same regions of the Earth, the zonal drift velocities of EPBs are derived using GOLD data. EPBs observed within 60–25°W longitudes on 27–29 November 2018 are considered in the present analysis. The drift velocities obtained on 27 November 2018 are 116 ± 4, 118 ± 6, and 105 ± 9 m/s at the North and South crests of equatorial ionization anomaly (EIA) and the magnetic equator, respectively. While on 29 November the velocities 107 ± 10, 106 ± 8, and 110 ± 4 m/s are in agreement with the 27th (within the uncertainties), on 28 November the velocities are substantially lower: 80 ± 3, 95 ± 7, and 88 ± 11 m/s. This is the first simultaneous measurement of EPB zonal drift velocities at both crests of EIA and the magnetic equator. On 27–29 November 2018, the average spacing between adjacent EPBs is found to be ~377, 526, and 442 km, respectively.
Nighttime Ionospheric TEC Study Over Latin America During Moderate and High Solar Activity
Authors: Romero‐Hernandez E. , Denardini C. M. , Jonah O. F. , Essien P. , Picanço G. A. S. , Nogueira P. A. B. , Rodriguez‐Martinez M. , Resende L. C. A. , de la Luz V. , Aguilar‐Rodriguez E. , Sergeeva M. , Gonzalez‐Esparza J. A. , Takahashi H. , Perez‐Tijerina E. 
Published: August 2020

AbstractThe present work is a comprehensive study of the ionospheric vertical total electron content (vTEC) variations during the nighttime, based on data collected by ground‐based Global Navigation Satellite System (GNSS) receivers over the Latin American region. We provide a qualitative and quantitative analysis of the ionospheric vTEC trend at 21:00, 00:00, and 03:00 local time (LT), during geomagnetically undisturbed days of 2011 (ascending phase) and 2014 (maximum phase), which encompassed (a) the response to the solar flux variation, (b) the seasonal trend in different latitudes and longitudes, and (c) the interhemispheric asymmetry. One significant result of this study is the development of TEC maps for the Latin American region, which are used for the monitoring and forecasting of the ionosphere for space weather purposes. The nighttime vTEC variations showed a strong latitudinal dependence, especially in the Northern Hemisphere. For 2011, the semiannual anomaly was similar to that observed in daytime; however, in 2014, the receivers at midlatitude presented asymmetric behavior. Similarly, the nighttime winter anomaly (NWA) was very weak in both years. The Equatorial Ionospheric Anomaly (EIA) signature was absent from June to August, a period in which the hemispheric disparity in the vTEC values became more evident, suggesting a feeble interhemispheric circulation. The Midlatitude Summer Nighttime Anomaly (MSNA) was also identified in the Southern Hemisphere, during January and February of 2011 (moderate solar activity). Model approximations suggest that the equatorward winds and the EIA were involved in the formation of the MSNA.
Excitation Mechanism of Ionospheric 6‐Day Oscillation During the 2019 September Sudden Stratospheric Warming Event
Authors: Miyoshi Yasunobu , Yamazaki Yosuke 
Published: August 2020

AbstractA sudden stratospheric warming (SSW) event in the Antarctic region occurred in September 2019. During the SSW event, the quasi 6‐day wave (Q6DW) was enhanced in the mesosphere, and strong 6‐day oscillations are observed in ionospheric parameters, such as the equatorial electrojet (EEJ) and electron density. The 6‐day variation in the EEJ has a westward moving structure with the zonal wave number 1, indicating the influence of the Q6DW. In this study, we investigate the excitation mechanism of the 6‐day variations in the EEJ and electron density using numerical simulations. The main results are as follows. The 6‐day variations in the ionosphere are not generated by the Q6DW but generated by the waves with periods from 10 to 14 hr. The amplitude of the 10–14 hr waves is modulated with a period of 6 days, due to the nonlinear interaction between the Q6DW and migrating semidiurnal tide. This leads to the 6‐day variations in the EEJ and electron density through the E region dynamo process. At a fixed local time, the secondary waves generated by the Q6DW‐tidal interaction produce westward moving ionospheric 6‐day variations with zonal wave number 1, which cannot be distinguished from the ionospheric variations by the Q6DW itself. The interference of secondary waves leads to a longitudinal asymmetry in the magnitude of the ionospheric 6‐day oscillation.
Ionosphere Feedback to Electron Scattering by Equatorial Whistler Mode Waves
Authors: Artemyev A. V. , Zhang X.‐J. , Angelopoulos V. , Mourenas D. , Vainchtein D. , Shen Y. , Vasko I. , Runov A. 
Published: August 2020

AbstractPlasma sheet electron precipitation, much of it driven by whistler mode waves, is critical for magnetosphere‐ionosphere coupling. This precipitation leads to a secondary electron population at low altitudes, which moves upward along magnetic field lines to the equatorial plasma sheet. We investigate observational evidence for such electron precipitation and the ionospheric feedback provided by the secondary electron outflows. Using the near‐equatorial Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission, we show that whistler mode wave bursts are accompanied by enhanced field‐aligned electrons. The properties of these electrons are not related to the whistler mode waves, as would have been expected from local wave‐particle interactions. Thus, it is unlikely that the field‐aligned electrons are formed by electron Landau resonance with whistler mode waves. This population can be the secondary electron outflows resulting from plasma sheet electron precipitation to the ionosphere. Combining THEMIS, Cluster, and Fast Auroral Snapshot Explorer (FAST) measurements, we show that this field‐aligned electron population is also observed at low altitudes, where it is associated with high‐frequency electrostatic waves. These low‐altitude waves are likely generated by the secondary electron outflows and, in turn, scatter these electrons outside of the loss cone, allowing them to be observed by the wide field‐of‐view particle instrument on the near‐equatorial THEMIS spacecraft. We discuss how this secondary electron population can subsequently alter whistler mode wave generation and propagation in the magnetosphere.
How Does Viscosity Contrast Influence Phase Mixing and Strain Localization?
Authors: Cross Andrew J. , Olree Elizabeth , Couvy Hélène , Skemer Philip 
Published: August 2020

AbstractUltramylonites—intensely deformed rocks with fine grain sizes and well‐mixed mineral phases—are thought to be a key component of Earth‐like plate tectonics, because coupled phase mixing and grain boundary pinning enable rocks to deform by grain‐size‐sensitive, self‐softening creep mechanisms over long geologic timescales. In isoviscous two‐phase composites, “geometric” phase mixing occurs via the sequential formation, attenuation (stretching), and disaggregation of compositional layering. However, the effects of viscosity contrast on the mechanisms and timescales for geometric mixing are poorly understood. Here, we describe a series of high‐strain torsion experiments on nonisoviscous calcite‐fluorite composites (viscosity contrast, ηca/ηfl ≈ 200) at 500°C, 0.75 GPa confining pressure, and 10−6–10−4 s−1 shear strain rate. At low to intermediate shear strains (γ ≤ 10), polycrystalline domains of the individual phases become sheared and form compositional layering. As layering develops, strain localizes into the weaker phase, fluorite. Strain partitioning impedes mixing by reducing the rate at which the stronger (calcite) layers deform, attenuate, and disaggregate. Even at very large shear strains (γ ≥ 50), grain‐scale mixing is limited, and thick compositional layers are preserved. Our experiments (1) demonstrate that viscosity contrasts impede mechanical phase mixing and (2) highlight the relative inefficiency of mechanical mixing. Nevertheless, by employing laboratory flow laws, we show that “ideal” conditions for mechanical phase mixing may be found in the wet middle to lower continental crust and in the dry mantle lithosphere, where quartz‐feldspar and olivine‐pyroxene viscosity contrasts are minimized, respectively.
Accelerated Snow Melt in the Russian Caucasus Mountains After the Saharan Dust Outbreak in March 2018
Authors: Dumont M. , Tuzet F. , Gascoin S. , Picard G. , Kutuzov S. , Lafaysse M. , Cluzet B. , Nheili R. , Painter T. H. 
Published: August 2020

Light absorbing particles, such as mineral dust, are a potent climate forcing agent. Many snow‐covered areas are subject to dust outbreak events originating from desert regions able to significantly decrease snow albedo. Here, using a combination of Sentinel‐2 imagery, in situ measurements and ensemble detailed snowpack simulations, we study the impact on snow cover duration of a major dust deposition event that occurred in the Caucasus in March 2018. This is, to the best of our knowledge, the first study using ensemble approach and Sentinel‐2 imagery to quantify the impact of a dust event on the snow cover evolution. We demonstrate that the calculation of the impact is strongly affected by the snow model uncertainties but that the March 2018 dust event systematically shortened the snow cover duration in Western Caucasus. The shortening is higher for location with higher accumulation and higher elevation (median values of 23 ± 7 days) than for location at lower elevation (median values of 15 ± 3 days). This is because for sites with higher location and higher accumulation, melt occurs later in the season when more incoming solar energy is available. This highlights the huge impact of a single 1‐day event on snow cover duration, and consequently, on the hydrology of a large region.
Atmospheric Precipitation and Anomalous Upper Mantle in Relation to Intraplate Seismicity in Norway
Authors: Maystrenko Yuriy Petrovich , Brönner Marco , Olesen Odleiv , Saloranta Tuomo Mikael , Slagstad Trond 
Published: August 2020

AbstractTwo enigmatic regions of high intraplate seismicity in Norway (Western Norway and the Nordland area) show a temporal correlation between the number of earthquakes within the upper crystalline crust and intensity of rain and snowmelt at the Earth's surface. This correlation is obvious in the Nordland area where detailed and reliable data on seismicity are available, whereas the correlation is weaker in Western Norway where detailed data on seismicity are missing. Moreover, these discrete zones of high seismic activity coincide spatially with prominent, low‐velocity, and, most likely, thermally anomalous zones in the upper mantle. We propose that in addition to other causes, the high seismicity may be controlled by the anomalous upper mantle, along with topographically induced gravitational potential energy and crustal density variations. Precipitation‐induced, seasonal increases in pore‐fluid pressure within the fractured crystalline bedrock and changes in water loads may modulate the tectonically controlled seismicity.
Microfluidics for interrogating live intact tissues
Authors: Horowitz Lisa F. , Rodriguez Adán D. , Ray Tyler , Folch Albert 
Published: August 2020

AbstractThe intricate microarchitecture of tissues – the “tissue microenvironment” – is a strong determinant of tissue function. Microfluidics offers an invaluable tool to precisely stimulate, manipulate, and analyze the tissue microenvironment in live tissues and engineer mass transport around and into small tissue volumes. Such control is critical in clinical studies, especially where tissue samples are scarce, in analytical sensors, where testing smaller amounts of analytes results in faster, more portable sensors, and in biological experiments, where accurate control of the cellular microenvironment is needed. Microfluidics also provides inexpensive multiplexing strategies to address the pressing need to test large quantities of drugs and reagents on a single biopsy specimen, increasing testing accuracy, relevance, and speed while reducing overall diagnostic cost. Here, we review the use of microfluidics to study the physiology and pathophysiology of intact live tissues at sub-millimeter scales. We categorize uses as either in vitro studies – where a piece of an organism must be excised and introduced into the microfluidic device – or in vivo studies – where whole organisms are small enough to be introduced into microchannels or where a microfluidic device is interfaced with a live tissue surface (e.g. the skin or inside an internal organ or tumor) that forms part of an animal larger than the device. These microfluidic systems promise to deliver functional measurements obtained directly on intact tissue – such as the response of tissue to drugs or the analysis of tissue secretions – that cannot be obtained otherwise.
A wireless, implantable optoelectrochemical probe for optogenetic stimulation and dopamine detection
Authors: Liu Changbo , Zhao Yu , Cai Xue , Xie Yang , Wang Taoyi , Cheng Dali , Li Lizhu , Li Rongfeng , Deng Yuping , Ding He , Lv Guoqing , Zhao Guanlei , Liu Lei , Zou Guisheng , Feng Meixin , Sun Qian , Yin Lan , Sheng Xing 
Published: August 2020

AbstractPhysical and chemical technologies have been continuously progressing advances in neuroscience research. The development of research tools for closed-loop control and monitoring neural activities in behaving animals is highly desirable. In this paper, we introduce a wirelessly operated, miniaturized microprobe system for optical interrogation and neurochemical sensing in the deep brain. Via epitaxial liftoff and transfer printing, microscale light-emitting diodes (micro-LEDs) as light sources and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)-coated diamond films as electrochemical sensors are vertically assembled to form implantable optoelectrochemical probes for real-time optogenetic stimulation and dopamine detection capabilities. A customized, lightweight circuit module is employed for untethered, remote signal control, and data acquisition. After the probe is injected into the ventral tegmental area (VTA) of freely behaving mice, in vivo experiments clearly demonstrate the utilities of the multifunctional optoelectrochemical microprobe system for optogenetic interference of place preferences and detection of dopamine release. The presented options for material and device integrations provide a practical route to simultaneous optical control and electrochemical sensing of complex nervous systems.
Immune-based therapies in the management of multiple myeloma
Authors: Zanwar Saurabh , Nandakumar Bharat , Kumar Shaji 
Published: August 2020

AbstractMultiple myeloma (MM) is a clonal plasma cell malignancy affecting a predominantly elderly population. The continued development of newer therapies with novel mechanisms of action has reshaped the treatment paradigm of this disorder in the last two decades, leading to a significantly improved prognosis. This has in turn resulted in an increasing number of patients in need of therapy for relapsed/refractory disease. Immune-based therapies, including monoclonal antibodies, immune checkpoint inhibitors, and most promisingly, adoptive cellular therapies represent important therapeutic strategies in these patients due to their non-cross resistant mechanisms of actions with the usual frontline therapies comprising of immunomodulatory drugs (IMiDs) and proteasome inhibitors (PIs). The anti-CD38 antibodies daratumumab and more recently isatuximab, with their excellent efficacy and safety profile along with its synergy in combination with IMiDs and PIs, are being increasingly incorporated in the frontline setting. Chimeric antigen receptor–T cell (CART) therapies and bi-specific T-cell engager (BiTE) represent exciting new options that have demonstrated efficacy in heavily pretreated and refractory MM. In this review, we discuss the rationale for use of immune-based therapies in MM and summarize the currently available literature for common antibodies and CAR-T therapies that are utilized in MM.
Small molecules targeting RORγt inhibit autoimmune disease by suppressing Th17 cell differentiation
Authors: Tan Jun , Liu Huan , Huang Minhao , Li Na , Tang Shibing , Meng Jiayu , Tang Shiyun , Zhou Hongxiu , Kijlstra Aize , Yang Peizeng , Hou Shengping 
Published: August 2020

AbstractTh17 cells, a lymphocyte subpopulation that is characterized by the expression of the transcription factor “retinoic acid receptor-related orphan receptor gamma-t” (RORγt), plays an important role in the pathogenesis of autoimmune disease. The current study was set up to discover novel and non-steroidal small-molecule inverse agonists of RORγt and to determine their effects on autoimmune disease. Structure-based virtual screening (SBVS) was used to find compounds targeting RORγt. Flow cytometry was used to detect the Th17 cell differentiation. Inverse agonists were intraperitoneally administered to mice undergoing experimental autoimmune uveitis (EAU), experimental autoimmune encephalomyelitis (EAE) or type 1 diabetes. The effects of the inverse agonists were evaluated by clinical or histopathological scoring. Among 1.3 million compounds screened, CQMU151 and CQMU152 were found to inhibit Th17 cell differentiation without affecting the differentiation of Th1 and Treg lineages (both P = 0.001). These compounds also reduced the severity of EAU (P = 0.01 and 0.013) and functional studies showed that they reduced the number of Th17 cell and the expression of IL-17(Th17), but not IFN-γ(Th1) and TGF-β(Treg) in mouse retinas. Further studies showed that these compounds may reduce the expression of p-STAT3 by reducing the positive feedback loop of IL-17/IL-6/STAT3. These compounds also reduced the impaired blood–retinal barrier function by upregulating the expression of tight junction proteins. These compounds were also found to reduce the severity of EAE and type 1 diabetes. Our results showed that RORγt inverse agonists may inhibit the development of autoimmune diseases and may provide new clues for the treatment of Th17-mediated immune diseases.