bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intraseasonal Variations of Nonmigrating Tides Observed Near the Mesopause
Authors: Liu Guiping , Janches Diego , Lieberman Ruth S. 
Published: November 2018

AbstractNonmigrating tides excited in the tropical troposphere by latent heat release from deep convection are known to be responsible for introducing the longitudinal structures in the upper atmosphere and the ionosphere. This study presents for the first time an extensive analysis of the prominent wave‐3 and wave‐4 longitudinal structures using nearly 14 years of temperature observations by the Microwave Limb Sounder instrument operated on the Aura satellite from 2004 to 2017. The observations reveal significant intraseasonal (~30–60 days) periodic variations in the amplitudes of these wave structures at ~97‐km altitude near the mesopause. Some large wave amplitudes accompany strong activity of the Madden‐Julian Oscillation. Rainfall data from the Tropical Rainfall Measuring Mission are used as a proxy of latent heating to investigate the source of these variations. Intraseasonal signatures in the wave structures are observed to coincide with the rainfall variations, indicating that the tropospheric 30‐ to 60‐day oscillation is an important driver of the same periodic changes in the upper atmosphere. Given that not all intraseasonal oscillations in the lower atmosphere have corresponding signatures in the longitudinal wave structures, the atmospheric conditions and other influences are important. This study provides evidence on the connection between intraseasonal variations of tides in the upper atmosphere and the changes in the forcing by latent heat release in the troposphere.
Statistical Study on the Occurrences of Postsunset Ionospheric E, Valley, and F Region Irregularities and Their Correlations Over Low‐Latitude Sanya
Authors: Xie Haiyong , Li Guozhu , Zhao Xiukuan , Hu Lianhuan , Wu Baoyuan , Ning Baiqi 
Published: November 2018

AbstractThe coupling of equatorial and low‐latitude ionosphere has been an active area of research for many years. At low latitude, the occurrences of E and valley region irregularities during postsunset hours are obviously different from those around the magnetic equator. In this work, we statistically investigated the occurrences of postsunset ionospheric E, valley, and F region irregularities, the postsunset rise of F layer, and their correlations by using the Sanya (18.4°N, 109.6°E, dip latitude 12.8°N) very high frequency radar and ionosonde observations during equinoctial months of 2012–2016. A statistically significant correlation between the presence of valley region irregularities and that of equatorial spread F (ESF) was found over Sanya. For the days without ESF, valley region irregularity was rarely observed. The Doppler velocities of valley region irregularities were mainly upward which resemble those of simultaneous ESF irregularities. On the other hand, an occurrence peak of E region irregularities was detected around sunset. After sunset, E region irregularity echo was frequently disrupted. The disruption can appear on both ESF and non‐ESF days, when the amplitudes of F layer postsunset rise were significantly different. The effects of polarization electric field associated with ESF and of equatorial ionospheric background condition on the E and valley region irregularities over Sanya are discussed.
Zonal Drift Velocity of Equatorial Plasma Bubbles During Ascending Phase of 24th Solar Cycle Using All‐Sky Imager Over Kolhapur, India
Authors: Gurav O. B. , Sharma A. K. , Ghodpage R. N. , Nade D. P. , Chavan G. A. , Gaikwad H. P. , Patil P. T. 
Published: November 2018

AbstractThis paper reports the statistical analysis of zonal drift velocity of equatorial plasma bubbles (EPBs) inferred from advanced optical technique (all‐sky imager) with OI 630.0‐nm airglow emission from January to April of 2011 to 2013. Over 143 nights of observations have been carried out using all‐sky imager over low‐latitude station Kolhapur (16.8°N, 74.2°E; 10.6°N dip latitude), out of which 58 nights showed signatures of EPBs. We study the hourly, monthly, and seasonal variation in zonal drift velocity of EPBs. Also, the magnetically disturbed nights (Ap > 18) are separately studied. It is observed that (a) the daily peak zonal drift velocity is seen to be positively correlated to corresponding daily averaged 10.7‐cm solar flux. (b) The zonal drift velocity is found to be larger in the equinox months than that of winter months. (c) During the disturbed nights the zonal drift velocity gets slower and one of the disturbed nights showed the latitudinal variation in zonal drift velocity during the development phase of EPBs before midnight hours. We suggest that this variation might be occurred due to the disturbance dynamo electric fields at low latitude, which reduces the EPBs' eastward velocity. (d) The zonal drift velocity of EPBs presented in this paper is in good agreement with the previous studies as well as the HWM‐07 model values.
Investigating Solar Wind‐Driven Electric Field Influence on Long‐Term Dynamics of Jovian Synchrotron Radiation
Authors: Han S. , Murakami G. , Kita H. , Tsuchiya F. , Tao C. , Misawa H. , Yamazaki A. , Nakamura M. 
Published: November 2018

AbstractSince the first discovery of Jovian Synchrotron Radiation (JSR) from Jovian radiation belt in late 1950s, origin of its time variations has been one of the main subjects of the Jovian radiation belt study. JSR is reported to be strongly correlated with solar wind ram pressure with a possible time lag, which remains an unsolved issue. In our study, the influence of dawn‐to‐dusk electric field modulated with solar wind ram pressure on JSR variations is investigated. Alongside the original diffusion coefficient (DLL(UV)), a new diffusion coefficient (DLL(Elec)) which is dependent on solar wind conditions is applied to a one‐dimensional lossy radial diffusion model, and we reproduce long‐term variations of JSR between 1971 and early 2018. For the specific choice of DLL(UV) = 3.0 × 10−10L3[s−1], the correlation coefficient is found to be 0.6 between the simulated JSR and the ground observation data prior to 2005, and the intermittent observation after 2005 supports our simulation as well. We suggest that while DLL(UV) is the primary mode of diffusion that determines the steady profile of electron population and JSR, DLL(Elec) serves as a secondary mode, which controls long‐term variations of JSR.
Response of Earth's Upper Atmosphere and VLF Propagation to Celestial X‐Ray Ionization: Investigation With Monte Carlo Simulation and Long Wave Propagation Capability code
Authors: Palit Sourav , Raulin Jean‐Pierre , Szpigel Sérgio 
Published: November 2018

AbstractIonization of Earth's upper atmosphere by celestial and terrestrial sources of radiation is the driver of most of the significant physical and chemical evolution distributed over a large range of timescales. Part of the atmosphere, called ionosphere, owes its existence to the ionization of neutral molecules by cosmic rays and solar ultraviolet radiation. Solar flares, with extreme ultraviolet and soft X‐rays, modulate the lower part of the ionosphere for few minutes up to few hours. Currently, plenty of signatures of hard X‐ray and gamma ray ionization effects on the middle and upper atmosphere due to extragalactic sources like gamma ray bursts and soft gamma repeaters have been observed. Most of such events, which look like spikes of X‐ray radiation, are manifested in impulsive ionization and gradual decay due to atmospheric recombination processes. Such ionization source profile in form of delta function in time or a spike is the most ideal and simplest candidate to investigate the basics of X‐ray ionization influences on atmospheric chemistry and plasma characteristics. Here with a Monte Carlo simulation and a simple ion chemistry model we investigate numerically the effect of such X‐ray ionization impulses, with different source characteristics, on various layers of the Earth's atmosphere and those on very low frequency (VLF) radio wave propagation. We also justify our assumption that in terms of their effect on atmosphere and VLF, any actual source of ionization may be considered as a bunch of consecutive ionization spikes of varying intensity and spectral characteristics.
Improvement of the IRI Model Using F2 Layer Parameters Derived From GPS/COSMIC Radio Occultation Observations
Authors: Wu M. J. , Guo P. , Fu N. F. , Hu X. G. , Hong Z. J. 
Published: November 2018

AbstractIn this study, an improved ionospheric model is presented by applying self‐specified F2 layer parameters and an adaptive topside model into the International Reference Ionosphere (IRI) model. Three F2 layer parameters, the critical frequency (foF2), peak height (hmF2), and the scale height (Hsc) obtained from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations, are modeled by spherical harmonics expansion. The empirical orthogonal functions are used to construct the associated parameters in the adaptive topside model. The improved model is validated by incoherent scatter radar (ISR) data of Millstone station and the Global Ionospheric Maps. Results show that the NmF2 and hmF2 of improved model have better agreement with ISR measurements. The vertical total electron content deviation compared with Global Ionospheric Map is discussed in different seasons and levels of solar activity. With radio occultation‐based parameters, the accuracy of original IRI model is improved by 1 total electron content unit globally on average.
Magma Chamber and Crustal Channel Flow Structures in the Tengchong Volcano Area From 3‐D MT Inversion at the Intracontinental Block Boundary Southeast of the Tibetan Plateau
Authors: Ye Tao , Huang Qinghua , Chen Xiaobin , Zhang Huiqian , Chen Y. John , Zhao Li , Zhang Yong 
Published: November 2018

AbstractBased on magnetotelluric (MT) array data, we have obtained the first three‐dimensional (3‐D) electrical resistivity model at the Gaoligong intracontinental block boundary in southeastern Tibetan Plateau where the Quaternary intraplate Tengchong volcanism and seismic activities occur. Comparing with results of previous geophysical studies in the area, our MT model clearly reveals three conductive bodies in the depth ranges of 10–30 km in the Tengchong volcano area, which we interpret as three middle‐lower crustal magma chambers associated with the Tengchong volcanism. Seismogenic faults in the Gaoligong Shear Zone (GLGSZ) are characterized by subvertical conductive zones bounded by resistive upper crustal layer on both sides. Earthquakes of moderate magnitudes near the GLGSZ have all occurred within the conductive fault zones at the bottom of the upper resistive crust. More importantly, one large resistive body was imaged at middle‐lower crustal depth beneath the GLGSZ, which seems to block the previously proposed horizontal crustal channel flow along this intracontinental block boundary. Our 3‐D model indicates that crustal channel flow could take place east of the GLGSZ. The current study provides evidence from electrical resistivity structure for the middle‐lower crustal magma chambers in the Tengchong volcano area and detailed 3‐D electrical structure of crustal channel flow in this active tectonic region.
Analysis of a Record‐Breaking Strong Wind Event at Syowa Station in January 2015
Authors: Yamada K. , Hirasawa N. 
Published: November 2018

AbstractSyowa Station in Antarctica observed a January record strong surface wind on 17 January 2015 with a maximum mean wind speed of 41.8 m/s. The strong wind event is studied here using the Weather Research and Forecasting model. The event occurred under the influence of enhanced northerly wind associated with an intense synoptic‐scale depression that approached the west of Syowa station. The northerly wind turned easterly along the coast of the ice sheet with remarkable near‐surface acceleration. The acceleration of the surface wind at Syowa Station was connected with the establishment of the easterly low‐level jet that formed as a result of orographic blocking as follows: (1) Air with low potential temperature around the southern end of the northerly wind was forced to ascend by the slope of the ice sheet; (2) the upwelling transported air from the lower atmosphere, resulting in the establishment of a cold region along the slope; (3) the deformed temperature structure generated a strengthening horizontal pressure gradient; and (4) the negative pressure gradient ∂p/∂y was larger at lower altitudes, resulting in stronger easterly wind in the lower layer, consistent with thermal wind balance. During the strong wind event, katabatic wind was enhanced by the greater katabatic force associated with the stronger negative pressure gradient. Another interesting feature was a local warming at surface level in Lutzow‐Holm Bay. The warming was driven by a foehn mechanism. The other branch of the downslope wind upwelled again above the bay, and this upwelling extended up to the tropopause.
Increase in Precipitation Efficiency With Surface Warming in Radiative‐Convective Equilibrium
Authors: Lutsko Nicholas J. , Cronin Timothy W. 
Published: November 2018

AbstractThe precipitation efficiency of convection (ε) plays an important role in simple models of the tropical atmosphere as well as in global climate models' projections of future climate changes, but remains poorly understood and poorly constrained. A particularly urgent question is how ε will change in warmer climates. To address these issues, this study investigates the precipitation efficiency in simulations of radiative‐convective equilibrium with a cloud‐resolving model forced by a wide range of sea surface temperatures (SSTs). Two different domains are considered: a small, doubly periodic domain, and a 2‐D (x‐z) “mock‐Walker” domain with a sinusoidal SST profile that resembles the equatorial Pacific, and the sensitivities of the results to the microphysical scheme and to the horizontal resolution are also explored. It is found that ε generally increases with warming in the small domain simulations because of increases in the efficiency with which cloud condensate is converted into precipitation, with changes in the re‐evaporation of falling precipitation playing a secondary role. This picture is complicated in the 2‐D simulations by substantial changes in the degree of convective organization as the underlying SSTs are varied. ε is found to decrease as convection becomes more organized, because convective organization results in relatively more low clouds, which have small (≤0.1) precipitation efficiencies, and relatively less high clouds, which have larger (∼0.4) precipitation efficiencies.
ISGF3 with reduced phosphorylation is associated with constitutive expression of interferon-induced genes in aging cells
Authors: Yamagami Mari , Otsuka Motoyuki , Kishikawa Takahiro , Sekiba Kazuma , Seimiya Takahiro , Tanaka Eri , Suzuki Tatsunori , Ishibashi Rei , Ohno Motoko , Koike Kazuhiko 
Published: November 2018

AbstractDuring cellular aging, many changes in cellular functions occur. A hallmark of aged cells is secretion of inflammatory mediators, which collectively is referred to as the senescence-associated secretory phenotype (SASP). However, the mechanisms underlying such changes are unclear. Canonically, the expression of interferon (IFN)-stimulated genes (ISGs) is induced by IFNs through the formation of the tripartite transcriptional factor ISGF3, which is composed of IRF9 and the phosphorylated forms of STAT1 and STAT2. However, in this study, the constitutive expression of ISGs in human-derived senescent fibroblasts and in fibroblasts from a patient with Werner syndrome, which leads to premature aging, was mediated mainly by the unphosphorylated forms of STATs in the absence of INF production. Under homeostatic conditions, STAT1, STAT2, and IRF9 were localized to the nucleus of aged cells. Although knockdown of JAK1, a key kinase of STAT1 and STAT2, did not affect ISG expression or IFN-stimulated response element (ISRE)-mediated promoter activities in these senescent cells, knockdown of STAT1 or STAT2 decreased ISG expression and ISRE activities. These results suggest that the ISGF3 complex without clear phosphorylation is required for IFN-independent constitutive ISG transcription in senescent cells.
Improving analytical reasoning and argument understanding: a quasi-experimental field study of argument visualization
Authors: Cullen Simon , Fan Judith , van der Brugge Eva , Elga Adam 
Published: November 2018

AbstractThe ability to analyze arguments is critical for higher-level reasoning, yet previous research suggests that standard university education provides only modest improvements in students’ analytical-reasoning abilities. What pedagogical approaches are most effective for cultivating these skills? We investigated the effectiveness of a 12-week undergraduate seminar in which students practiced a software-based technique for visualizing the logical structures implicit in argumentative texts. Seminar students met weekly to analyze excerpts from contemporary analytic philosophy papers, completed argument visualization problem sets, and received individualized feedback on a weekly basis. We found that seminar students improved substantially more on LSAT Logical Reasoning test forms than did control students (d = 0.71, 95% CI: [0.37, 1.04], p < 0.001), suggesting that learning how to visualize arguments in the seminar led to large generalized improvements in students’ analytical-reasoning skills. Moreover, blind scoring of final essays from seminar students and control students, drawn from a parallel lecture course, revealed large differences in favor of seminar students (d = 0.87, 95% CI: [0.26, 1.48], p = 0.005). Seminar students understood the arguments better, and their essays were more accurate and effectively structured. Taken together, these findings deepen our understanding of how visualizations support logical reasoning and provide a model for improving analytical-reasoning pedagogy.
Psychophysiological correlates between emotional response inhibition and posttraumatic stress symptom clusters
Authors: Duan Hongxia , Wang Li , Wu Jianhui 
Published: November 2018

AbstractPost-traumatic Stress Disorder (PTSD) is characterized by diverse executive function impairments as well as abnormal emotion processing. The goal of the present study was to examine the relationships between emotional response inhibition and distinct PTSD symptom clusters from a six-factor DSM-5 model. Event-related potentials (ERPs) were measured in an emotional Go/NoGo task among 58 adult survivors from a deadly earthquake. Overall, the commission errors were lower and reaction time was faster for negative pictures compared to neutral pictures. The negative pictures elicited a smaller N2 but larger P3 amplitude compared to neutral and positive pictures, and larger P3 amplitude was further associated with a faster response. Multivariate regression models showed that the PCL score was related to smaller NoGo-N2 amplitude in the negative context, suggesting that the severity of posttraumatic stress symptoms is associated with worse conflict detection. Furthermore, the severity of anhedonia symptom cluster rather than negative affect symptom cluster was associated with fewer commission errors in the positive context, and this result provided electrophysiological evidence for the six-factor model, i.e., a distinction should be made between negative affect symptom cluster and anhedonia symptom cluster.
Structural Basis for Binding of Allosteric Drug Leads in the Adenosine A1 Receptor
Authors: Miao Yinglong , Bhattarai Apurba , Nguyen Anh T. N. , Christopoulos Arthur , May Lauren T. 
Published: November 2018

AbstractDespite intense interest in designing positive allosteric modulators (PAMs) as selective drugs of the adenosine A1 receptor (A1AR), structural binding modes of the receptor PAMs remain unknown. Using the first X-ray structure of the A1AR, we have performed all-atom simulations using a robust Gaussian accelerated molecular dynamics (GaMD) technique to determine binding modes of the A1AR allosteric drug leads. Two prototypical PAMs, PD81723 and VCP171, were selected. Each PAM was initially placed at least 20 Å away from the receptor. Extensive GaMD simulations using the AMBER and NAMD simulation packages at different acceleration levels captured spontaneous binding of PAMs to the A1AR. The simulations allowed us to identify low-energy binding modes of the PAMs at an allosteric site formed by the receptor extracellular loop 2 (ECL2), which are highly consistent with mutagenesis experimental data. Furthermore, the PAMs stabilized agonist binding in the receptor. In the absence of PAMs at the ECL2 allosteric site, the agonist sampled a significantly larger conformational space and even dissociated from the A1AR alone. In summary, the GaMD simulations elucidated structural binding modes of the PAMs and provided important insights into allostery in the A1AR, which will greatly facilitate the receptor structure-based drug design.
Androgen induced cellular proliferation, neurogenesis, and generation of GnRH3 neurons in the brain of mature female Mozambique tilapia
Authors: Narita Yasuto , Tsutiya Atsuhiro , Nakano Yui , Ashitomi Moe , Sato Kenjiro , Hosono Kohei , Kaneko Toyoji , Chen Ruo-Dong , Lee Jay-Ron , Tseng Yung-Che , Hwang Pung-Pung , Ohtani-Kaneko Ritsuko 
Published: November 2018

AbstractThe neuroplastic mechanisms in the fish brain that underlie sex reversal remain unknown. Gonadotropin-releasing hormone 3 (GnRH3) neurons control male reproductive behaviours in Mozambique tilapia and show sexual dimorphism, with males having a greater number of GnRH3 neurons. Treatment with androgens such as 11-ketotestosterone (KT), but not 17β-estradiol, increases the number of GnRH3 neurons in mature females to a level similar to that observed in mature males. Compared with oestrogen, the effect of androgen on neurogenesis remains less clear. The present study examined the effects of 11-KT, a non-aromatizable androgen, on cellular proliferation, neurogenesis, generation of GnRH3 neurons and expression of cell cycle-related genes in mature females. The number of proliferating cell nuclear antigen-positive cells was increased by 11-KT. Simultaneous injection of bromodeoxyuridine and 11-KT significantly increased the number of newly-generated (newly-proliferated) neurons, but did not affect radial glial cells, and also resulted in newly-generated GnRH3 neurons. Transcriptome analysis showed that 11-KT modulates the expression of genes related to the cell cycle process. These findings suggest that tilapia could serve as a good animal model to elucidate the effects of androgen on adult neurogenesis and the mechanisms for sex reversal in the fish brain.