bluuebunny/crossref_metadata_2025 huggingface dataset:
Sustainability and the financial system Review of literature 2015
Authors: Aspinall N. G. , Jones S. R. , McNeill E. H. , Werner R. A. , Zalk T.
Published: May 2018

Much actuarial work is underpinned by the use of economic models derived from mainstream academic theories of finance and economics which treat money as being a neutral medium of exchange. The sustainability of a financial system whose understanding is based on a limited view of the role of money has increasingly been subject to criticism. In order to identify needed research programmes to address such criticisms and improve these disciplines, we sought to understand the current state of knowledge in economics and finance concerning the link between monetary and financial factors and sustainability. We have approached this through a search for relevant literature published in the highest-rated academic journals in economics, finance and the social sciences for titles and abstracts containing both references to the financial system on the one hand, and sustainability and environmental factors on the other. The systematic search of a universe of 125 journals and 355,000 articles yielded the finding that surprisingly few research papers jointly address these concepts. Nevertheless, we find that current research shares a broad consensus that the implications of the growth-oriented economic model results in an increasingly interconnected and fragile financial system whose participants are not incentivised to fully recognise the natural environment and resource constraints. We further observe that the prescriptions offered are relatively limited and small-scale in their outlook and that there is a vital need for further research, particularly for actuaries who are required to take a longer-term outlook. The Resource and Environment Board has supported this work with two key objectives: first, to identify research that may have direct application to actuarial work and, second, to identify gaps in academic research that would help drive the Institute and Faculty of Actuaries’ own research agenda. With this in mind there are three further areas of potential actuarial research. These are the policy aim of pursuing growth without limit within a finite ecosystem; discount factors as the primary means of capital allocation and investment decisions; and the use of gross domestic product as the key metric of economic activity and success. We also conclude that further academic research is urgently needed to understand the sustainability of the banking and monetary system.
RANDOM SPARSE SAMPLING IN A GIBBS WEIGHTED TREE AND PHASE TRANSITIONS
Authors: Barral Julien , Seuret Stéphane
Published: May 2018

Let $\unicode[STIX]{x1D707}$ be the projection on $[0,1]$ of a Gibbs measure on $\unicode[STIX]{x1D6F4}=\{0,1\}^{\mathbb{N}}$ (or more generally a Gibbs capacity) associated with a Hölder potential. The thermodynamic and multifractal properties of $\unicode[STIX]{x1D707}$ are well known to be linked via the multifractal formalism. We study the impact of a random sampling procedure on this structure. More precisely, let $\{{I_{w}\}}_{w\in \unicode[STIX]{x1D6F4}^{\ast }}$ stand for the collection of dyadic subintervals of $[0,1]$ naturally indexed by the finite dyadic words. Fix $\unicode[STIX]{x1D702}\in (0,1)$, and a sequence $(p_{w})_{w\in \unicode[STIX]{x1D6F4}^{\ast }}$ of independent Bernoulli variables of parameters $2^{-|w|(1-\unicode[STIX]{x1D702})}$. We consider the (very sparse) remaining values $\widetilde{\unicode[STIX]{x1D707}}=\{\unicode[STIX]{x1D707}(I_{w}):w\in \unicode[STIX]{x1D6F4}^{\ast },p_{w}=1\}$. We study the geometric and statistical information associated with $\widetilde{\unicode[STIX]{x1D707}}$, and the relation between $\widetilde{\unicode[STIX]{x1D707}}$ and $\unicode[STIX]{x1D707}$. To do so, we construct a random capacity $\mathsf{M}_{\unicode[STIX]{x1D707}}$ from $\widetilde{\unicode[STIX]{x1D707}}$. This new object fulfills the multifractal formalism, and its free energy is closely related to that of $\unicode[STIX]{x1D707}$. Moreover, the free energy of $\mathsf{M}_{\unicode[STIX]{x1D707}}$ generically exhibits one first order and one second order phase transition, while that of $\unicode[STIX]{x1D707}$ is analytic. The geometry of $\mathsf{M}_{\unicode[STIX]{x1D707}}$ is deeply related to the combination of approximation by dyadic numbers with geometric properties of Gibbs measures. The possibility to reconstruct $\unicode[STIX]{x1D707}$ from $\widetilde{\unicode[STIX]{x1D707}}$ by using the almost multiplicativity of $\unicode[STIX]{x1D707}$ and concatenation of words is discussed as well.
Dormancy-linked Population Structure of Weedy Rice (Oryzasp.)
Authors: Tseng Te-Ming , Shivrain Vinod K. , Lawton-Rauh Amy , Burgos Nilda R.
Published: May 2018

Seed dormancy allows weedy rice (Oryzasp.) to persist in rice production systems. Weedy and wild relatives of rice (Oryza sativaL.) exhibit different levels of dormancy, which allows them to escape weed management tactics, increasing the potential for flowering synchronization, and therefore gene flow, between weedyOryzasp. and cultivated rice. In this study, we determined the genetic diversity and divergence of representative dormant and nondormant weedyOryzasp. groups from Arkansas. Twenty-five simple sequence repeat markers closely associated with seed dormancy were used. Four populations were included: dormant blackhull, dormant strawhull, nondormant blackhull, and nondormant strawhull. The overall gene diversity was 0.355, indicating considerable genetic variation among populations in these dormancy-related loci. Gene diversity among blackhull populations (0.398) was higher than among strawhull populations (0.245). Higher genetic diversity was also observed within and among dormant populations than in nondormant populations. Cluster analysis of 16 accessions, based on Nei’s genetic distance, showed four clusters. Clusters I, III, and IV consisted of only blackhull accessions, whereas Cluster II comprised only strawhull accessions. These four clusters did not separate cleanly into dormant and nondormant populations, indicating that not all markers were tightly linked to dormancy. The strawhull groups were most distant from blackhull weedyOryzasp. groups. These data indicate complex genetic control of the dormancy trait, as dormant individuals exhibited higher genetic diversity than nondormant individuals. Seed-dormancy trait contributes to population structure of weedyOryzasp., but this influence is less than that of hull color. Markers unique to the dormant populations are good candidates for follow-up studies on the control of seed dormancy in weedyOryzasp.
Melt‐Fluxed Melting of the Heterogeneously Mixed Lower Arc Crust: A Case Study from the Qinling Orogenic Belt, Central China
Authors: Wu Kai , Ling Ming‐Xing , Hu Yong‐Bin , Guo Jia , Jiang Xiao‐Yan , Sun Sai‐Jun , Liang Hua‐Ying , Liu Xu , Sun Weidong
Published: May 2018

Adakitic rocks with high MgO content and lower crust affinity at convergent margins provide important constraints on arc crust evolution and regional tectonics. An integrated study on the only adakitic pluton with high MgO content and its mafic microgranular enclaves (MMEs) in the Early Paleozoic North Qinling arc terrane was conducted in this paper. Zircons from 2 host rock samples yielded identical weighted mean ages of 428 Ma. The MMEs contain two types of zircons: type 1 zircons share similar morphology, chemical composition, and indistinguishable age with those from the host rock; type 2 zircons yielded an older age of 450 Ma. The similarity in zircon Hf isotopic composition for these zircons indicates a cognate origin of the MMEs. However, the lower Ce4+/Ce3+, higher crystallization temperature and the LREE overabundance of type 2 zircons indicate that mafic intrusions in the lower arc crust were subjected to a post‐magmatic event at ∼450 Ma. Samples from the Tangzang pluton are characterized by typical adakitic geochemical features, and high MgO (Mg#: 50–52), Cr, Ni, and Ba contents. Considering their similar isotopic compositions with the Neoproterozoic metabasites in the North Qinling terrane, we argue that the Tangzang pluton was generated by crustal anatexis of two sources with contributions from the metasomatized mantle wedge. The mantle connection was achieved by aqueous melt‐fluxed melting of a “hot zone” in the lower arc crust. This implies that andesitic continental crust with Mg# of ∼0.5 may also be associated with fluxed‐melting of the lower arc crust.
Simultaneous Observations of Polar Mesosphere Winter Echoes and Cosmic Noise Absorptions in a Common Volume by the PANSY Radar (69.0°S, 39.6°E)
Authors: Nishiyama T. , Sato K. , Nakamura T. , Tsutsumi M. , Sato T. , Tanaka Y.‐M. , Nishimura K. , Tomikawa Y. , Kohma M.
Published: May 2018

This study focuses on the one‐to‐one relationship between the morphology of polar mesosphere winter echo (PMWE) and cosmic noise absorption (CNA) as determined by measurements made with a single atmospheric radar, the Program of the Antarctic Syowa mesosphere‐stratosphere‐troposphere/incoherent scatter (PANSY) radar. CNA was calculated using the noise level in radar signal data collected during May 2013, including data of a solar proton event on 23 May. Using PMWE and CNA data in a common volume, their temporal variations and relation were examined in detail. PMWE altitude was clearly anticorrelated with CNA magnitude in a statistical sense: When a large CNA exceeding 0.50 dB took place, PMWE seemed to concentrate around 65 km and disappear above 70 km. The electron density behind the PMWE was estimated by using the ionospheric model for the auroral zone for the solar proton event. PMWE occurrence roughly coincided with a high electron density in the model, except that no PMWE was observed above 70 km at 0730 UT despite the electron density being higher than 108 m−3. Additionally, the estimated radar volume reflectivity with the Schmidt number Sc less than or equal to 1 is qualitatively consistent with the observed PMWE. Although weak turbulent energy dissipation rate can also play a dominant role in the observed PMWE decay, a plausible mechanism was small Sc or reduction of Sc that is equal to an increase in electron diffusivity resulting from an unusually high electron density, which significantly reduced radar volume reflectivity above 70 km.
Field‐Aligned Currents in Saturn's Magnetosphere: Observations From the F‐Ring Orbits
Authors: Hunt G. J. , Provan G. , Bunce E. J. , Cowley S. W. H. , Dougherty M. K. , Southwood D. J.
Published: May 2018

We investigate the azimuthal magnetic field signatures associated with high‐latitude field‐aligned currents observed during Cassini's F‐ring orbits (October 2016–April 2017). The overall ionospheric meridional current profiles in the northern and southern hemispheres, that is, the regions poleward and equatorward of the field‐aligned currents, differ most from the 2008 observations. We discuss these differences in terms of the seasonal change between data sets and local time (LT) differences, as the 2008 data cover the nightside while the F‐ring data cover the post‐dawn and dusk sectors in the northern and southern hemispheres, respectively. The F‐ring field‐aligned currents typically have a similar four current sheet structure to those in 2008. We investigate the properties of the current sheets and show that the field‐aligned currents in a hemisphere are modulated by that hemisphere's “planetary period oscillation” (PPO) systems. We separate the PPO‐independent and PPO‐related currents in both hemispheres using their opposite symmetry. The average PPO‐independent currents peak at ~1.5 MA/rad just equatorward of the open closed field line boundary, similar to the 2008 observations. However, the PPO‐related currents in both hemispheres are reduced by ~50% to ~0.4 MA/rad. This may be evidence of reduced PPO amplitudes, similar to the previously observed weaker equatorial oscillations at similar dayside LTs. We do not detect the PPO current systems' interhemispheric component, likely a result of the weaker PPO‐related currents and their closure within the magnetosphere. We also do not detect previously proposed lower latitude discrete field‐aligned currents that act to “turn off” the PPOs.
Modeling and Predicting the Short‐Term Evolution of the Geomagnetic Field
Authors: Bärenzung Julien , Holschneider Matthias , Wicht Johannes , Sanchez Sabrina , Lesur Vincent
Published: May 2018

We propose a reduced dynamical system describing the coupled evolution of fluid flow and magnetic field at the top of the Earth's core between the years 1900 and 2014. The flow evolution is modeled with a first‐order autoregressive process, while the magnetic field obeys the classical frozen flux equation. An ensemble Kalman filter algorithm serves to constrain the dynamics with the geomagnetic field and its secular variation given by the COV‐OBS.x1 model. Using a large ensemble with 40,000 members provides meaningful statistics including reliable error estimates. The model highlights two distinct flow scales. Slowly varying large‐scale elements include the already documented eccentric gyre. Localized short‐lived structures include distinctly ageostophic features like the high‐latitude polar jet on the Northern Hemisphere. Comparisons with independent observations of the length‐of‐day variations not only validate the flow estimates but also suggest an acceleration of the geostrophic flows over the last century. Hindcasting tests show that our model outperforms simpler predictions bases (linear extrapolation and stationary flow). The predictability limit, of about 2,000 years for the magnetic dipole component, is mostly determined by the random fast varying dynamics of the flow and much less by the geomagnetic data quality or lack of small‐scale information.
Detectable Impact of Local and Remote Anthropogenic Aerosols on the 20th Century Changes of West African and South Asian Monsoon Precipitation
Authors: Undorf S. , Polson D. , Bollasina M. A. , Ming Y. , Schurer A. , Hegerl G. C.
Published: May 2018

Anthropogenic aerosols are a key driver of changes in summer monsoon precipitation in the Northern Hemisphere during the 20th century. Here we apply detection and attribution methods to investigate causes of change in the West African and South Asian monsoons separately and identify the aerosol source regions that are most important for explaining the observed changes during 1920–2005. Historical simulations with the GFDL‐CM3 model are used to derive fingerprints of aerosol forcing from different regions. For West Africa, remote aerosol emissions from North America and Europe (NAEU) are essential in order to detect the anthropogenic signal in observed monsoon precipitation changes. The changes are significantly underestimated in the model, however. While natural (volcanic) forcing seems to also play a role, the dominant contribution is found to come from aerosol‐induced changes in the interhemispheric temperature gradient and associated meridional shifts of the Intertropical Convergence Zone. For South Asia, in contrast, changes in observed monsoon precipitation cannot be explained without local emissions. Here the findings show a weakening of the monsoon circulation, driven by the increase of remote NAEU aerosol emissions until 1975, and since then by the increase in local emissions offsetting the decrease of NAEU emissions. The results show that the aerosol forcing from individual emission regions is strong enough to be detected over internal variability. They also underscore the importance of the spatial pattern of global‐aerosol emissions, which is likely to continue to change throughout the expected near‐future decline in global emissions.
The Climatological Effect of Saharan Dust on Global Tropical Cyclones in a Fully Coupled GCM
Authors: Strong Jeffrey D. O. , Vecchi Gabriel A. , Ginoux Paul
Published: May 2018

Climate in the tropical North Atlantic and West Africa is known to be sensitive to both the atmospheric burden and optical properties of aerosolized mineral dust. We investigate the global climatic response to an idealized perturbation in atmospheric burden of Saharan‐born mineral dust, comparable to the observed changes between the 1960s and 1980s, using simulations with the high‐resolution, fully coupled Geophysical Fluid Dynamics Laboratory Climate Model 2.5, Forecast‐oriented Low Ocean Resolution version, across a range of realistic optical properties, with a specific focus on tropical cyclones. The direct radiative responses at the top of the atmosphere and at the surface along with regional hydrologic and thermodynamic responses are in agreement with previous studies, depending largely on the amount of aerosol absorption versus scattering. In all simulations, dust causes a decrease in tropical cyclone activity across the North Atlantic Ocean, as determined by a tropical cyclone tracking scheme, with the largest response occurring in the most absorbing and scattering optical regimes. These changes are partially corroborated by common local genesis potential indices. However, no clear‐cut explanation can be developed upon inspection of their constituent variables. There are also nonnegligible anomalies in the North Pacific and Indian Oceans in these simulations. A relationship between accumulated cyclone energy and top of the atmosphere radiative flux anomalies is used to explain the North Atlantic anomalies, while analogy to known climate variations can help us understand the far‐field response to the dust forcing.
Gas Emissions From Volcanoes of the Kuril Island Arc (NW Pacific): Geochemistry and Fluxes
Authors: Taran Yuri , Zelenski Mikhail , Chaplygin Ilya , Malik Natalia , Campion Robin , Inguaggiato Salvatore , Pokrovsky Boris , Kalacheva Elena , Melnikov Dmitri , Kazahaya Ryunosuke , Fischer Tobias
Published: May 2018

The Kuril Island arc extending for about 1,200 km from Kamchatka Peninsula to Hokkaido Island is a typical active subduction zone with ∼40 historically active subaerial volcanoes, some of which are persistently degassing. Seven Kurilian volcanoes (Ebeko, Sinarka, Kuntomintar, Chirinkotan, Pallas, Berg, and Kudryavy) on six islands (Paramushir, Shiashkotan, Chirinkotan, Ketoy, Urup, and Iturup) emit into the atmosphere > 90% of the total fumarolic gas of the arc. During the field campaigns in 2015–2017 direct sampling of fumaroles, MultiGas measurements of the fumarolic plumes and DOAS remote determinations of the SO2 flux were conducted on these volcanoes. Maximal temperatures of the fumaroles in 2015–2016 were 510°C (Ebeko), 440°C (Sinarka), 260°C (Kuntomintar), 720°C (Pallas), and 820°C (Kudryavy). The total SO2 flux (in metric tons per day) from fumarolic fields of the studied volcanoes was measured as ∼1,800 ± 300 t/d, and the CO2 flux is estimated as 1,250 ± 400 t/d. Geochemical characteristics of the sampled gases include δD and δ18O of fumarolic condensates, δ13C of CO2, δ34S of the total sulfur, ratios 3He/4He and 40Ar/36Ar, concentrations of the major gas species, and trace elements in the volcanic gas condensates. The mole ratios C/S are generally <1. All volcanoes of the arc, except the southernmost Mendeleev and Golovnin volcanoes on Kunashir Island, emit gases with 3He/4He values of >7RA (where RA is the atmospheric 3He/4He). The highest 3He/4He ratios of 8.3RA were measured in fumaroles of the Pallas volcano (Ketoy Island) in the middle of the arc.
Interaction of the Interplanetary Shock and IMF Directional Discontinuity in the Solar Wind
Authors: Goncharov O. , Koval A. , Šafránková J. , Němeček Z. , Stevens M. L. , Szabo A. , Přech L.
Published: May 2018

The solar wind is not stationary and variations of the magnetic field magnitude and/or direction and plasma parameters are frequent. Interactions of fast forward shocks and interplanetary magnetic field discontinuities with the bow shock were analyzed in details theoretically as well as experimentally. However, an oblique interaction between a fast‐forward interplanetary shock and a directional interplanetary magnetic field discontinuity was studied only within the framework of the ideal magnetohydrodynamics. A fortunate position of six spacecraft on 22 June 2015 facilitates detailed observations of an interplanetary shock modification due to the interaction with the directional discontinuity in the solar wind. We present a multispacecraft analysis of the event supported with magnetohydrodynamic (MHD) modeling showing that this interaction can lead to a bifurcation of the velocity jump across the shock.
Propagation of Seismogenic Electric Currents Through the Earth's Atmosphere
Authors: Denisenko V. V. , Boudjada M. Y. , Lammer H.
Published: May 2018

Seismogenic models have been recently proposed to explain precursors before earthquakes occurrences. Those models refer to physical processes linking the lithosphere, the atmosphere, and the ionosphere. We analyze in this work the curl‐free current model describing the current flow from the lithosphere to the ionosphere through the atmosphere. We use a numerical simulation based on the finite element method to derive the current between the ground and the ionosphere. We have shown that the curl‐free approximation of the atmospheric current density leads to significant and unpredictable distortions of the solutions of the electrical conductivity. Hence, it incorrectly expands the ionospheric disturbed region associated to lithospheric currents. It is shown that horizontally homogeneous vertical underground external currents cannot create currents from ground to the atmosphere.
Derivation of the Energy and Flux Morphology in an Aurora Observed at Midlatitude Using Multispectral Imaging
Authors: Aryal Saurav , Finn Susanna C. , Hewawasam Kuravi , Maguire Ryan , Geddes George , Cook Timothy , Martel Jason , Baumgardner Jeffrey L , Chakrabarti Supriya
Published: May 2018

Energies and fluxes of precipitating electrons in an aurora over Lowell, MA on 22–23 June 2015 were derived based on simultaneous, high‐resolution (≈ 0.02 nm) brightness measurements of
(427.8 nm, blue line), OI (557.7 nm, green line), and OI (630.0 nm, red line) emissions. The electron energies and energy fluxes as a function of time and look direction were derived by nonlinear minimization of model predictions with respect to the measurements. Three different methods were compared; in the first two methods, we constrained the modeled brightnesses and brightness ratios, respectively, with measurements to simultaneously derive energies and fluxes. Then we used a hybrid method where we constrained the individual modeled brightness ratios with measurements to derive energies and then constrained modeled brightnesses with measurements to derive fluxes. Derived energy, assuming Maxwellian distribution, during this storm ranged from 109 to 262 eV and the total energy flux ranged from 0.8 to 2.2 ergs·cm−2·s−1. This approach provides a way to estimate energies and energy fluxes of the precipitating electrons using simultaneous multispectral measurements.
Observation of Ionospheric Alfvén Resonances at 1–30 Hz and Their Superposition With the Schumann Resonances
Authors: Beggan C. D. , Musur M.
Published: May 2018

Long‐term measurements of the high‐frequency magnetic field (0.1–100 Hz) have been made at Eskdalemuir Observatory in the United Kingdom since September 2012. We analyze five years of dynamic spectrograms to examine the occurrence and behavior of the Schumann and ionospheric Alfvén resonances (IAR) and Pc1 pulsations. The resonances, observed as diffuse bands, arise from reflections of energy both within the Earth‐ionosphere cavity and from the nonlinear conductivity gradient of the ionosphere. Schumann Resonances (SR) occur continuously but IAR are observed to arise at local nighttime in ∼50% of days in the data set. Typically, IAR are found at frequencies of 1–8 Hz, but we find them extending out to 30 Hz and strongly superimposing over the first three Schumann resonances around 9% of the time. These phenomena include constructive and destructive interference, nonlinear frequency changes over the span of several hours, and polarity enhancements. In addition, the magnitude of the IAR does not decline rapidly with frequency as often proposed. We find that the IAR and their superposition with SR are strongly controlled by season and geomagnetic activity. We compare 6 days with the most unusual IAR behavior in the data set to ionosonde measurements of f0F2, a proxy for ionospheric conductivity but find little correlation. We suggest that, as current theoretical modeling does not account for these observations, further work is needed to understand how they arise.
PYSAT: Python Satellite Data Analysis Toolkit
Authors: Stoneback R. A. , Burrell A. G. , Klenzing J. , Depew M. D.
Published: May 2018

A common problem in space science data analysis is combining complementary data sources that are provided and analyzed in different formats and programming languages. The Python Satellite Data Analysis Toolkit (pysat) addresses this issue by providing an open source toolkit that implements the general process of space science data analysis, from beginning to end, in an instrument‐independent manner. This toolkit uses an Instrument object that enables systematic analysis of science data from a variety of platforms within a single interface. Basic functions such as downloading, loading, and cleaning are included for all supported instruments. Common analysis routines are also included, which are instrument and data source independent. A nanokernel is used to provide instrument independence, it is attached to the Instrument object and mediates the systematic and arbitrary modification of loaded data. Pysat uses the nanokernel to improve the rigor of time series analysis, support on‐the‐fly orbit determination, and cleanly span file breaks. Pysat's functions and higher‐level scientific analysis features are validated through the use of unit testing. Further adoption by the community provides a set of scientific results produced by a common core, constituting a distributed heritage that supports the validity of the underlying processing and scientific output. These features are used to demonstrate consistency between derived electron density profiles and measured ion drifts, particularly downward ion drifts in the afternoon hours during extreme solar minimum. Pysat builds upon open source Python software that is freely available and encourages community‐driven development.
The Ionospheric Impact of an ICME‐Driven Sheath Region Over Indian and American Sectors in the Absence of a Typical Geomagnetic Storm
Authors: Rout Diptiranjan , Chakrabarty D. , Sarkhel S. , Sekar R. , Fejer B. G. , Reeves G. D. , Kulkarni Atul S. , Aponte Nestor , Sulzer Mike , Mathews John D. , Kerr Robert B. , Noto John
Published: May 2018

On 13 April 2013, the ACE spacecraft detected arrival of an interplanetary shock at 2250 UT, which is followed by the passage of the sheath region of an interplanetary coronal mass ejection (ICME) for a prolonged (18‐hr) period. The polarity of interplanetary magnetic field Bz was northward inside the magnetic cloud region of the ICME. The ring current (SYM‐H) index did not go below −7 nT during this event suggesting the absence of a typical geomagnetic storm. The responses of the global ionospheric electric field associated with the passage of the ICME sheath region have been investigated using incoherent scatter radar measurements of Jicamarca and Arecibo (postmidnight sector) along with the variations of equatorial electrojet strength over India (day sector). It is found that westward and eastward prompt penetration (PP) electric fields affected ionosphere over Jicamarca/Arecibo and Indian sectors, respectively, during 0545–0800 UT. The polarities of the PP electric field perturbations over the day/night sectors are consistent with model predictions. In fact, DP2‐type electric field perturbations with ∼40‐min periodicity are found to affect the ionosphere over both the sectors for about 2.25 hr during the passage of the ICME sheath region. This result shows that SYM‐H index may not capture the full geoeffectivenss of the ICME sheath‐driven storms and suggests that the PP electric field perturbations should be evaluated for geoeffectiveness of ICME when the polarity of interplanetary magnetic field Bz is northward inside the magnetic cloud region of the ICME.
Episodes of Aqueous Flooding and Effusive Volcanism Associated With Hrad Vallis, Mars
Authors: Hamilton Christopher W. , Mouginis‐Mark Peter J. , Sori Michael M. , Scheidt Stephen P. , Bramson Ali M.
Published: May 2018

Hrad Vallis is an Amazonian‐age outflow channel located in the northwestern part of the Elysium Volcanic Province of Mars. The formation of Hrad Vallis may have been associated with catastrophic aqueous floods and volcanism, which makes determining its emplacement history important for constraining the planet's hydrological and thermal evolution during the Amazonian Period. Through geological mapping, geomorphologic analysis, and numerical simulations we assess whether Hrad Vallis formed in association with mudflows (i.e., lahars), effusive volcanism, or a combination of both processes. Among the three youngest flows in the region, the lower and upper flow units are inferred to be the products of catastrophic aqueous floods, whereas the middle unit is interpreted to be pāhoehoe‐like lava flow formed through the process of inflation over the course of decades. The latter flow unit is similar to terrestrial lava‐rise plateaus, but its emplacement may have involved interactions with surficial ice deposits, which affected the flow path and resulted in a range of lava‐water interactions. We conclude that Hrad Vallis had a complex history involving episodes of both aqueous flooding and effusive volcanism and that the interactions between lava and ice in these regions may have generated ephemeral hydrothermal systems with potential astrobiological significance.
Modeling the Ionosphere with GPS and Rotation Measure Observations
Authors: Malins J. B. , White S. M. , Taylor G. B. , Stovall K. , Dowell J.
Published: May 2018

The ionosphere contributes time‐varying Faraday rotation (FR) to radio signals passing through it. Correction for the effect of the ionosphere is important for deriving magnetic field information from FR observations of polarized cosmic radio sources, as well as providing valuable diagnostics of the structure of the ionosphere. In this paper, we evaluate the accuracy of models commonly used to correct for its effects using new observations of pulsars at low frequencies, which provide total rotation measures (RMs) at better precision than previously available. We evaluate models of the ionosphere derived from modern digital ionosondes that provide electron density information as a function of height, as well as GPS‐derived total electron content (TEC) measurements. We combine these density models with reference global magnetic field models to derive ionospheric RM contributions. We find that the models disagree substantially with each other and seek corrections that may explain the differences in RM prediction. Additionally, we compare these models to global TEC models and find that local high‐cadence TEC measurements are superior to global models for ionospheric RM correction.
GADD45α sensitizes cervical cancer cells to radiotherapy via increasing cytoplasmic APE1 level
Authors: Li Qing , Wei Xi , Zhou Zhi-Wei , Wang Shu-Nan , Jin Hua , Chen Kui-Jun , Luo Jia , Westover Kenneth D. , Wang Jian-Min , Wang Dong , Xu Cheng-Xiong , Shan Jin-Lu
Published: May 2018

Radioresistance remains a major clinical challenge in cervical cancer therapy. However, the mechanism for the development of radioresistance in cervical cancer is unclear. Herein, we determined that growth arrest and DNA-damage-inducible protein 45α (GADD45α) is decreased in radioresistant cervical cancer compared to radiosensitive cancer both in vitro and in vivo. In addition, silencing GADD45α prevents cervical cancer cells from undergoing radiation-induced DNA damage, cell cycle arrest, and apoptosis. More importantly, our data show that the overexpression of GADD45α significantly enhances the radiosensitivity of radioresistant cervical cancer cells. These data show that GADD45α decreases the cytoplasmic distribution of APE1, thereby enhancing the radiosensitivity of cervical cancer cells. Furthermore, we show that GADD45α inhibits the production of nitric oxide (NO), a nuclear APE1 export stimulator, by suppressing both endothelial NO synthase (eNOS) and inducible NO synthase (iNOS) in cervical cancer cells. In conclusion, our findings suggest that decreased GADD45α expression significantly contributes to the development of radioresistance and that ectopic expression of GADD45α sensitizes cervical cancer cells to radiotherapy. GADD45α inhibits the NO-regulated cytoplasmic localization of APE1 through inhibiting eNOS and iNOS, thereby enhancing the radiosensitivity of cervical cancer cells.
Inhibitor of apoptosis proteins are required for effective fusion of autophagosomes with lysosomes
Authors: Gradzka Sylwia , Thomas Oliver S. , Kretz Oliver , Haimovici Aladin , Vasilikos Lazaros. , Wong Wendy Wei-Lynn , Häcker Georg , Gentle Ian E.
Published: May 2018

Inhibitor of Apoptosis Proteins act as E3 ubiquitin ligases to regulate NF-κB signalling from multiple pattern recognition receptors including NOD2, as well as TNF Receptor Superfamily members. Loss of XIAP in humans causes X-linked Lymphoproliferative disease type 2 (XLP-2) and is often associated with Crohn’s disease. Crohn’s disease is also caused by mutations in the gene encoding NOD2 but the mechanisms behind Crohn’s disease development in XIAP and NOD2 deficient-patients are still unknown. Numerous other mutations causing Crohn’s Disease occur in genes controlling various aspects of autophagy, suggesting a strong involvement of autophagy in preventing Crohn’s disease. Here we show that the IAP proteins cIAP2 and XIAP are required for efficient fusion of lysosomes with autophagosomes. IAP inhibition or loss of both cIAP2 and XIAP resulted in a strong blockage in autophagic flux and mitophagy, suggesting that XIAP deficiency may also drive Crohn’s Disease due to defects in autophagy.
Grail is involved in adipocyte differentiation and diet-induced obesity
Authors: Liu Peiyao , Hsieh Poshiuan , Lin Huitsu , Liu Tejung , Wu Hsuehling , Chen Chengcheung , Chen Yingchuan
Published: May 2018

Grail is a crucial regulator of various biological processes, including the development of T-cell anergy, antiviral innate immune response, and cancer. However, the role of Grail in adipogenesis and obesity remains unclear. Here, we demonstrated that Grail knockdown in vitro leads to a decrease in PPARγ expression, resulting in adipogenesis inhibition. However, Grail overexpression induced the same effects. Grail was shown to interact with PPARγ, targeting it for degradation and modulating its adipogenic activity. PPARγ expression was shown to be considerably reduced in Grail knockout (KO) mice fed normal diet or high-fat diet (HFD). The administration of both normal diet or HFD to Grail KO mice led to lower adipose mass and body weight than those in the wild-type mice. HFD-fed Grail KO mice had improved glucose and insulin tolerance. Taken together, our results indicate that Grail plays a pivotal role in adipogenesis and diet-induced obesity by regulating PPARγ activity.
A CRISPRi screen in E. coli reveals sequence-specific toxicity of dCas9
Authors: Cui Lun , Vigouroux Antoine , Rousset François , Varet Hugo , Khanna Varun , Bikard David
Published: May 2018

High-throughput CRISPR-Cas9 screens have recently emerged as powerful tools to decipher gene functions and genetic interactions. Here we use a genome-wide library of guide RNAs to direct the catalytically dead Cas9 (dCas9) to block gene transcription in Escherichia coli. Using a machine-learning approach, we reveal that guide RNAs sharing specific 5-nucleotide seed sequences can produce strong fitness defects or even kill E. coli regardless of the other 15 nucleotides of guide sequence. This effect occurs at high dCas9 concentrations and can be alleviated by tuning the expression of dCas9 while maintaining strong on-target repression. Our results also highlight the fact that off-targets with as little as nine nucleotides of homology to the guide RNA can strongly block gene expression. Altogether this study provides important design rules to safely use dCas9 in E. coli.
Tracking HIV-1 recombination to resolve its contribution to HIV-1 evolution in natural infection
Authors: Song Hongshuo , Giorgi Elena E. , Ganusov Vitaly V. , Cai Fangping , Athreya Gayathri , Yoon Hyejin , Carja Oana , Hora Bhavna , Hraber Peter , Romero-Severson Ethan , Jiang Chunlai , Li Xiaojun , Wang Shuyi , Li Hui , Salazar-Gonzalez Jesus F. , Salazar Maria G. , Goonetilleke Nilu , Keele Brandon F. , Montefiori David C. , Cohen Myron S. , Shaw George M. , Hahn Beatrice H. , McMichael Andrew J. , Haynes Barton F. , Korber Bette , Bhattacharya Tanmoy , Gao Feng
Published: May 2018

Recombination in HIV-1 is well documented, but its importance in the low-diversity setting of within-host diversification is less understood. Here we develop a novel computational tool (RAPR (Recombination Analysis PRogram)) to enable a detailed view of in vivo viral recombination during early infection, and we apply it to near-full-length HIV-1 genome sequences from longitudinal samples. Recombinant genomes rapidly replace transmitted/founder (T/F) lineages, with a median half-time of 27 days, increasing the genetic complexity of the viral population. We identify recombination hot and cold spots that differ from those observed in inter-subtype recombinants. Furthermore, RAPR analysis of longitudinal samples from an individual with well-characterized neutralizing antibody responses shows that recombination helps carry forward resistance-conferring mutations in the diversifying quasispecies. These findings provide insight into molecular mechanisms by which viral recombination contributes to HIV-1 persistence and immunopathogenesis and have implications for studies of HIV transmission and evolution in vivo.
Symmetry mismatch-driven perpendicular magnetic anisotropy for perovskite/brownmillerite heterostructures
Authors: Zhang Jing , Zhong Zhicheng , Guan Xiangxiang , Shen Xi , Zhang Jine , Han Furong , Zhang Hui , Zhang Hongrui , Yan Xi , Zhang Qinghua , Gu Lin , Hu Fengxia , Yu Richeng , Shen Baogen , Sun Jirong
Published: May 2018

Grouping different transition metal oxides together by interface engineering is an important route toward emergent phenomenon. While most of the previous works focused on the interface effects in perovskite/perovskite heterostructures, here we reported on a symmetry mismatch-driven spin reorientation toward perpendicular magnetic anisotropy in perovskite/brownmillerite heterostructures, which is scarcely seen in tensile perovskite/perovskite heterostructures. We show that alternately stacking perovskite La2/3Sr1/3MnO3 and brownmillerite LaCoO2.5 causes a strong interface reconstruction due to symmetry discontinuity at interface: neighboring MnO6 octahedra and CoO4 tetrahedra at the perovskite/brownmillerite interface cooperatively relax in a manner that is unavailable for perovskite/perovskite interface, leading to distinct orbital reconstructions and thus the perpendicular magnetic anisotropy. Moreover, the perpendicular magnetic anisotropy is robust, with an anisotropy constant two orders of magnitude greater than the in-plane anisotropy of the perovskite/perovskite interface. The present work demonstrates the great potential of symmetry engineering in designing artificial materials on demand.
Sensible heat has significantly affected the global hydrological cycle over the historical period
Authors: Myhre G. , Samset B. H. , Hodnebrog Ø. , Andrews T. , Boucher O. , Faluvegi G. , Fläschner D. , Forster P. M. , Kasoar M. , Kharin V. , Kirkevåg A. , Lamarque J.-F. , Olivié D. , Richardson T. B. , Shawki D. , Shindell D. , Shine K. P. , Stjern C. W. , Takemura T. , Voulgarakis A.
Published: May 2018

Globally, latent heating associated with a change in precipitation is balanced by changes to atmospheric radiative cooling and sensible heat fluxes. Both components can be altered by climate forcing mechanisms and through climate feedbacks, but the impacts of climate forcing and feedbacks on sensible heat fluxes have received much less attention. Here we show, using a range of climate modelling results, that changes in sensible heat are the dominant contributor to the present global-mean precipitation change since preindustrial time, because the radiative impact of forcings and feedbacks approximately compensate. The model results show a dissimilar influence on sensible heat and precipitation from various drivers of climate change. Due to its strong atmospheric absorption, black carbon is found to influence the sensible heat very differently compared to other aerosols and greenhouse gases. Our results indicate that this is likely caused by differences in the impact on the lower tropospheric stability.
STT3-dependent PD-L1 accumulation on cancer stem cells promotes immune evasion
Authors: Hsu Jung-Mao , Xia Weiya , Hsu Yi-Hsin , Chan Li-Chuan , Yu Wen-Hsuan , Cha Jong-Ho , Chen Chun-Te , Liao Hsin-Wei , Kuo Chu-Wei , Khoo Kay-Hooi , Hsu Jennifer L. , Li Chia-Wei , Lim Seung-Oe , Chang Shih-Shin , Chen Yi-Chun , Ren Guo-xin , Hung Mien-Chie
Published: May 2018

Enriched PD-L1 expression in cancer stem-like cells (CSCs) contributes to CSC immune evasion. However, the mechanisms underlying PD-L1 enrichment in CSCs remain unclear. Here, we demonstrate that epithelial–mesenchymal transition (EMT) enriches PD-L1 in CSCs by the EMT/β-catenin/STT3/PD-L1 signaling axis, in which EMT transcriptionally induces N-glycosyltransferase STT3 through β-catenin, and subsequent STT3-dependent PD-L1 N-glycosylation stabilizes and upregulates PD-L1. The axis is also utilized by the general cancer cell population, but it has much more profound effect on CSCs as EMT induces more STT3 in CSCs than in non-CSCs. We further identify a non-canonical mesenchymal–epithelial transition (MET) activity of etoposide, which suppresses the EMT/β-catenin/STT3/PD-L1 axis through TOP2B degradation-dependent nuclear β-catenin reduction, leading to PD-L1 downregulation of CSCs and non-CSCs and sensitization of cancer cells to anti-Tim-3 therapy. Together, our results link MET to PD-L1 stabilization through glycosylation regulation and reveal it as a potential strategy to enhance cancer immunotherapy efficacy.
Nanographenes as electron-deficient cores of donor-acceptor systems
Authors: Liu Yu-Min , Hou Hao , Zhou Yan-Zhen , Zhao Xin-Jing , Tang Chun , Tan Yuan-Zhi , Müllen Klaus
Published: May 2018

Conjugation of nanographenes (NGs) with electro-active molecules can establish donor-acceptor π-systems in which the former generally serve as the electron-donating moieties due to their electronic-rich nature. In contrast, here we report a series of reversed donor-acceptor structures are obtained by C–N coupling of electron-deficient perchlorinated NGs with electron-rich anilines. Selective amination at the vertexes of the NGs is unambiguously shown through X-ray crystallography. By varying the donating ability of the anilino groups, the optical and assembly properties of donor-acceptor NGs can be finely modulated. The electron-deficient concave core of the resulting conjugates can host electron-rich guest molecules by intermolecular donor-acceptor interactions and gives rise to charge-transfer supramolecular architectures.
Ratchet-free solid-state inertial rotation of a guest ball in a tight tubular host
Authors: Matsuno Taisuke , Nakai Yusuke , Sato Sota , Maniwa Yutaka , Isobe Hiroyuki
Published: May 2018

Dynamics of molecules in the solid state holds promise for connecting molecular behaviors with properties of bulk materials. Solid-state dynamics of [60]fullerene (C60) is controlled by intimate intermolecular contacts and results in restricted motions of a ratchet phase at low temperatures. Manipulation of the solid-state dynamics of fullerene molecules is thus an interesting yet challenging problem. Here we show that a tubular host for C60 liberates the solid-state dynamics of the guest from the motional restrictions. Although the intermolecular contacts between the host and C60 were present to enable a tight association with a large energy gain of –14 kcal mol–1, the dynamic rotations of C60 were simultaneously enabled by a small energy barrier of +2 kcal mol–1 for the reorientation. The solid-state rotational motions reached a non-Brownian, inertial regime with an extremely rapid rotational frequency of 213 GHz at 335 K.
Abnormal band bowing effects in phase instability crossover region of GaSe1-xTe
x
nanomaterials
Authors: Cai Hui , Chen Bin , Blei Mark , Chang Shery L. Y. , Wu Kedi , Zhuang Houlong , Tongay Sefaattin
Published: May 2018

Akin to the enormous number of discoveries made through traditional semiconductor alloys, alloying selected 2D semiconductors enables engineering of their electronic structure for a wide range of new applications. 2D alloys have been demonstrated when two components crystallized in the same phase, and their bandgaps displayed predictable monotonic variation. By stabilizing previously unobserved compositions and phases of GaSe1−xTe
x
at nanoscales on GaAs(111), we demonstrate abnormal band bowing effects and phase instability region when components crystallize in different phases. Advanced microscopy and spectroscopy measurements show as tellurium is alloyed into GaSe, nanostructures undergo hexagonal to monoclinic and isotropic to anisotropic transition. There exists an instability region (0.56 < x < 0.67) where both phases compete and coexist, and two different bandgap values can be found at the same composition leading to anomalous band bowing effects. Results highlight unique alloying effects, not existing in single-phase alloys, and phase engineering routes for potential applications in photonic and electronics.
Coherent X-rays reveal the influence of cage effects on ultrafast water dynamics
Authors: Perakis Fivos , Camisasca Gaia , Lane Thomas J. , Späh Alexander , Wikfeldt Kjartan Thor , Sellberg Jonas A. , Lehmkühler Felix , Pathak Harshad , Kim Kyung Hwan , Amann-Winkel Katrin , Schreck Simon , Song Sanghoon , Sato Takahiro , Sikorski Marcin , Eilert Andre , McQueen Trevor , Ogasawara Hirohito , Nordlund Dennis , Roseker Wojciech , Koralek Jake , Nelson Silke , Hart Philip , Alonso-Mori Roberto , Feng Yiping , Zhu Diling , Robert Aymeric , Grübel Gerhard , Pettersson Lars G. M. , Nilsson Anders
Published: May 2018

The dynamics of liquid water feature a variety of time scales, ranging from extremely fast ballistic-like thermal motion, to slower molecular diffusion and hydrogen-bond rearrangements. Here, we utilize coherent X-ray pulses to investigate the sub-100 fs equilibrium dynamics of water from ambient conditions down to supercooled temperatures. This novel approach utilizes the inherent capability of X-ray speckle visibility spectroscopy to measure equilibrium intermolecular dynamics with lengthscale selectivity, by measuring oxygen motion in momentum space. The observed decay of the speckle contrast at the first diffraction peak, which reflects tetrahedral coordination, is attributed to motion on a molecular scale within the first 120 fs. Through comparison with molecular dynamics simulations, we conclude that the slowing down upon cooling from 328 K down to 253 K is not due to simple thermal ballistic-like motion, but that cage effects play an important role even on timescales over 25 fs due to hydrogen-bonding.