bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observation of Electron Conics by Juno: Implications for Radio Generation and Acceleration Processes
Authors: Louarn P. , Allegrini F. , McComas D. J. , Valek P. W. , Kurth W. S. , André N. , Bagenal F. , Bolton S. , Ebert R. W. , Imai M. , Levin S. , Szalay J. R. , Wilson R. J. 
Published: July 2018

AbstractUsing Juno plasma, electric and magnetic field observations (from JADE, Waves, and MAG instruments), we show that electron conic distributions are commonly observed in Jovian radio sources. The conics are characterized by maximum fluxes at oblique pitch angles, ~20°–30° from the B field, both in the upward and downward directions. They constitute an efficient source of free energy for the cyclotron maser instability. Growth rates of ~3 to 7 × 104 s−1 are obtained for hectometric waves, leading to amplification by e10 with propagation paths of 50–100 km. We show that stochastic acceleration due to interactions with a low‐frequency electric field turbulence located a few 104 km above the ionosphere may form the observed conics. A possible source of turbulence could be inertial Alfvén waves, suggesting a connection between the auroral acceleration and generation of coherent radio emissions.
Morphologic Diversity of Martian Ripples: Implications for Large‐Ripple Formation
Authors: Lapotre M. G. A. , Ewing R. C. , Weitz C. M. , Lewis K. W. , Lamb M. P. , Ehlmann B. L. , Rubin D. M. 
Published: July 2018

AbstractLarge ripples with meter‐scale wavelengths are ubiquitous across Mars. Curiosity's traverse of the Bagnold Dune Field revealed a morphologic diversity of large Martian ripples that helps constrain their formative mechanism. Large ripples develop in isolated fields and on dunes. They form transversely and obliquely to longitudinally to the net sand‐flux direction in unimodally and bimodally distributed very fine to very coarse sand. They have either straight or sinuous crestlines. Inactive ripples are covered with dust, whereas migrating ripples are dust free. Here we present a unifying view of ripples that form in near‐bed sediment‐transport conditions (encompassing fluid‐drag and coarse‐grained ripples) to explain the range of large‐Martian‐ripple morphologies and expand the use of bedforms as environmental indicators.
Widespread Reemergence of Sea Surface Temperature Anomalies in the Global Oceans, Including Tropical Regions Forced by Reemerging Winds
Authors: Byju P. , Dommenget D. , Alexander M. A. 
Published: July 2018

AbstractSea surface temperature anomalies (SSTA) in portions of the extratropics are known to recur from one winter to the next without persisting through the intervening summer. Previous studies identified only a limited number of midlatitude regions where this reemergence occurs. Here we find that most of the global oceans exhibit winter‐to‐winter recurrence of SSTA. Indeed, recurrence of SSTA is the default process in the global ocean. Only regions strongly linked to El Niño do not show signs of SST reemergence. In midlatitudes, the temperature anomalies that recur persist below the shallow mixed layer in summer. However, SST recurrence is also found at some tropical locations and appears to be independent of subsurface ocean heat storage. Reemergence at these locations is linked to the recurrence of atmospheric drivers of SSTA, predominantly the wind‐stress forcing. Our results are supported by different ocean data sets and by state‐of‐the‐art climate model simulations.
Saturn's Atmosphere at 1–10 Kilometer Resolution
Authors: Ingersoll Andrew P. , Ewald Shawn P. , Sayanagi Kunio M. , Blalock John J. 
Published: July 2018

AbstractWe present images of Saturn from the final phases of the Cassini mission, including images with 0.5 km per pixel resolution, as high as any Saturn images ever taken. Notable features are puffy clouds resembling terrestrial cumulus, shadows indicating cloud height, dome and bowl shaped cloud structures indicating upwelling and downwelling in anticyclones and cyclones respectively, and filaments, which are thread‐like clouds that remain coherent over distances of 20,000 km. From the coherence of the filaments, we give upper bounds on the diffusivity and kinetic energy dissipation. A radiative transfer analysis by Sanz‐Requena et al. (2018) indicates that methane‐band imagery is most useful in determining cloud and haze properties in the 60–250 mbar pressure range. Our methane‐band imagery finds haze in this pressure range covering 64°‐74°planetocentric latitude. Filaments lie within the haze, and cumulus clouds lie below it, but pressure levels are uncertain below the 250 mbar level.
Extended Survey of Saturn Z‐Mode Wave Intensity Through Cassini's Final Orbits
Authors: Menietti J. D. , Averkamp T. F. , Ye S.‐Y. , Persoon A. M. , Morooka M. W. , Groene J. B. , Kurth W. S. 
Published: July 2018

AbstractSimilar to whistler mode chorus, Z‐mode emission is an efficient diffusive scatterer of electrons possibly resulting in resonant acceleration. We present results of a survey of both the low‐band (5 kHz) and for the first time the high‐band (20 kHz) intensity of these emissions, based on over 11 years of Cassini Radio and Plasma Wave Science instrument data including nine ring‐grazing orbits and two proximal orbits, which occurred at the end of the mission. We distinguish these emissions using density and polarization measurements and calculate the mean intensity as a function of frequency and spatial coordinates. We find that the average low‐band Z‐mode intensity peak is P0 ~7 × 10−8 nT2, while the high‐band peak is much lower at P0 ~10−9 nT2. The spatial distribution of intensity differs for each emission band implying different source regions and perhaps different source mechanisms.
Radial Transport and Plasma Heating in Jupiter's Magnetodisc
Authors: Ng C. S. , Delamere P. A. , Kaminker V. , Damiano P. A. 
Published: July 2018

AbstractThe ion temperature of the magnetosphere of Jupiter derived from Galileo PLS data was observed to increase by about an order of magnitude from 10 to 40 Jupiter radii. This suggests the presence of heating sources that counteract the adiabatic cooling effect of expanding plasma. There have been different attempts of explaining this phenomena, including a magnetohydrodynamic (MHD) turbulent heating model which is based on flux tube diffusion (Saur, Astrophys. J. Lett., 602, L137, 2004). We explore an alternate turbulent heating model based on advection, similar to models commonly used in solar wind heating. Based on spectral analysis of Galileo magnetometer (MAG) data, we find that observed MHD turbulence could potentially provide the required heating to explain some of the increase in plasma temperature. This indicates that advection is a more appropriate way to describe radial transport of plasma in the Jovian magnetosphere beyond 10 Jupiter radii.
How Different Are the Solar Wind‐Interplanetary Conditions and the Consequent Geomagnetic Activity During the Ascending and Early Descending Phases of the Solar Cycles 23 and 24?
Authors: Rawat Rashmi , Echer E. , Gonzalez W. D. 
Published: July 2018

AbstractThe current work investigates the possible solar wind‐interplanetary (SW‐IP) drivers of geomagnetic storms during the longest period (ascending to early descending phases) of the ongoing solar cycle (24). We present a comparative analysis between the two consecutive solar cycles (SCs) 23 and 24. Both the cycles exhibited dual peak feature as observed in the smoothed sunspot numbers SSNsmoothed. For both the cycles, second peak in the SSNsmoothed is higher than the first one as exhibited in the revised SSNsmoothed version. During the entire interval between the ascending to early descending phases (December 2008 to December 2016) of SC‐24, the southward directed Bz and the dawn‐dusk electric field (Ey) were consistently weaker as compared to that during similar interval of SC‐23 (May 1996 to July 2004). The geomagnetic field response represented by Dst index concurrently exhibited similar variation patterns during both the periods. A striking reduction in the intense storm occurrence rate by ∼75% was observed during the considered period of the current solar cycle in comparison to the previous cycle. However, moderate storm occurrence was reduced only by 32% in SC‐24 as compared to SC‐23, which could be attributed to the dominance of corotating interaction regions during SC‐24. No significant difference is found between the intense storm rates around the vernal and autumnal equinoxes in cycle 24, whereas distinct autumnal equinoctial dominance is evident for cycle 23. Further, within each cycle, there is no significant difference in the moderate storm rates around vernal and autumnal equinoxes.
Final Assembly of the Southwestern Central Asian Orogenic Belt as Constrained by the Evolution of the South Tianshan Orogen: Links With Gondwana and Pangea
Authors: Wang Xin‐Shui , Klemd Reiner , Gao Jun , Jiang Tuo , Li Ji‐Lei , Xue Sheng‐Chao 
Published: July 2018

AbstractThe South Tianshan Orogen marks the final assembly of the southwestern Central Asian Orogenic Belt (CAOB) and the Karakum–Tarim cratons. Here we present an integrated mineralogical, geochemical, and geochronological study of the Wuwamen ophiolitic mélange in the South Tianshan to better understand the tectonic evolution of the western CAOB and its links to Gondwana and Pangea. Mantle peridotites with mineral compositions similar to those of abyssal peridotites and basalts with N‐MORB geochemical affinities suggest that the Wuwamen ophiolite was formed in a mid‐ocean ridge setting. Arc‐related gabbro and plagiogranite stocks intruding the mantle peridotites yielded zircon U–Pb ages of 441.1 ± 4.2 and 442.8 ± 2.4 Ma, indicating that the Wuwamen ophiolite got emplaced prior to ~440 Ma. Sericite‐quartz schist from the ophiolitic mélange matrix with abundant 481–319 Ma detrital zircon grains is crosscut by a two‐mica granite dike with a zircon U–Pb age of 321.3 ± 1.7 Ma, thereby constraining the formation of the Wuwamen ophiolitic mélange at ~320 Ma. In conjunction with published data, we propose that the South Tianshan Ocean opened in the late Neoproterozoic and promoted the subsequent separation of microcontinents in the western CAOB from the northeast Gondwana margin during Gondwana assembly. Furthermore, the closure of the South Tianshan Ocean led to the final assembly of the southwestern CAOB and the Karakum–Tarim cratons and their incorporation into Pangea at ~320 Ma.
Paleomagnetism and Geochemistry of ~1144‐Ma Lamprophyre Dikes, Northwestern Ontario: Implications for the North American Polar Wander and Plate Velocities
Authors: Piispa Elisa J. , Smirnov Aleksey V. , Pesonen Lauri J. , Mitchell Roger H. 
Published: July 2018

AbstractWe present new paleomagnetic and geochemical data from a suite of the ~1144‐Ma ultramafic lamprophyre dikes that outcrop in the Canadian Shield northeast of Lake Superior (Ontario, Canada). Nineteen of 22 sampled dikes yielded consistent characteristic remanent magnetization directions of normal (n = 5) and reversed (n = 14) polarity. The primary origin of characteristic remanent magnetization is bolstered by positive baked contact tests and a reversal test. The group mean direction (D = 306.4°, I = 72.1°, α95 = 5.5°, N = 19) obtained from the lamprophyre dikes is statistically indistinguishable from the group mean direction (D = 297.4°, I = 65.5°, α95 = 8.3°, N = 8) previously reported for the nearly coeval ~1142‐Ma Abitibi dikes. The geochemistry of the lamprophyre dikes suggests strong affinity with magmas derived from ocean island basalt‐type mantle sources, consistent with the mantle plume hypothesis for the formation of the ~1.1‐Ga North American Midcontinent Rift. The similarity in age, trend, paleomagnetism, and geochemistry indicates that the lamprophyre and Abitibi dike suites represent the earliest magmatic event associated with the commencement of rifting. The combined mean direction (D = 303.1°, I = 70.2°, α95 = 4.5°, N = 27) corresponds to a paleomagnetic pole at Plat = 55.8°N, Plong = 220.0°E (A95 = 7.3°). The new pole merits the highest classification on the Q‐scale of paleomagnetic reliability and represents a key pole defining the North American apparent polar wander path during the late Mesoproterozoic. Combined with high‐quality data from the ~1108‐Ma Coldwell Complex, our data indicate an equatorward motion of Laurentia at 3.8 ± 1.4 cm/year, comparable with the present‐day velocities of continental plates, before switching to extremely rapid motion between ~1108 and ~1099 Ma.
Transport of Central American Fire Emissions to the U.S. Gulf Coast: Climatological Pathways and Impacts on Ozone and PM2.5
Authors: Wang Sing‐Chun , Wang Yuxuan , Estes Mark , Lei Ruixue , Talbot Robert , Zhu Liye , Hou Pei 
Published: July 2018

AbstractFire emissions from Mexico and Central America are transported regularly to the U.S. Gulf Coast every spring under prevailing circulation patterns and affect U.S. air quality. Here we use a GEOS‐Chem passive tracer simulation to develop the climatology of transport pathways of fire emissions over a long‐term time period of April and May 2002–2015 and estimate their adverse air quality effects for urban areas along the Gulf Coast. A conceptual model is presented to describe the transport mechanisms, which involve southerly low‐level jets in the lower troposphere and warm conveyor belt in the middle troposphere. The warm conveyor belts and the southerly low‐level jets explain 31% and 69% of the interannual variability of the mid‐altitude (1.5–6 km) and low‐altitude events (0–1.5 km), respectively. Considering both transport and fire emissions, approximately 9% of the study period (59–88 days of 854 days) were identified as large pollution events during which Central American fire emissions adversely impacted surface air quality at several major urban centers along the Gulf Coast, including Houston and Corpus Christi in TX, New Orleans in LA, Mobile in AL, and Pensacola in FL. Compared to clean maritime flow from the Gulf of Mexico, these events were estimated to result in average enhancements of maximum daily average 8‐hr (MDA8) ozone and daily PM2.5 (fine particulate matter <2.5 μm in diameter) in the Gulf Coast cities of 3–12 ppbv and 2–5 μg/m3, respectively. Only one ozone exceedance day (79 ppbv, on 18 May 2003) was found among the fire‐impact days for the Houston region.
Disruption of the psychiatric risk gene Ankyrin 3 enhances microtubule dynamics through GSK3/CRMP2 signaling
Authors: Garza Jacob C. , Qi Xiaoli , Gjeluci Klaudio , Leussis Melanie P. , Basu Himanish , Reis Surya A. , Zhao Wen Ning , Piguel Nicolas H. , Penzes Peter , Haggarty Stephen J. , Martens Gerard J. , Poelmans Geert , Petryshen Tracey L. 
Published: July 2018

AbstractThe ankyrin 3 gene (ANK3) is a well-established risk gene for psychiatric illness, but the mechanisms underlying its pathophysiology remain elusive. We examined the molecular effects of disrupting brain-specific Ank3 isoforms in mouse and neuronal model systems. RNA sequencing of hippocampus from Ank3+/− and Ank3+/+ mice identified altered expression of 282 genes that were enriched for microtubule-related functions. Results were supported by increased expression of microtubule end-binding protein 3 (EB3), an indicator of microtubule dynamics, in Ank3+/− mouse hippocampus. Live-cell imaging of EB3 movement in primary neurons from Ank3+/− mice revealed impaired elongation of microtubules. Using a CRISPR-dCas9-KRAB transcriptional repressor in mouse neuro-2a cells, we determined that repression of brain-specific Ank3 increased EB3 expression, decreased tubulin acetylation, and increased the soluble:polymerized tubulin ratio, indicating enhanced microtubule dynamics. These changes were rescued by inhibition of glycogen synthase kinase 3 (GSK3) with lithium or CHIR99021, a highly selective GSK3 inhibitor. Brain-specific Ank3 repression in neuro-2a cells increased GSK3 activity (reduced inhibitory phosphorylation) and elevated collapsin response mediator protein 2 (CRMP2) phosphorylation, a known GSK3 substrate and microtubule-binding protein. Pharmacological inhibition of CRMP2 activity attenuated the rescue of EB3 expression and tubulin polymerization in Ank3-repressed cells by lithium or CHIR99021, suggesting microtubule instability induced by Ank3 repression is dependent on CRMP2 activity. Taken together, our data indicate that ANK3 functions in neuronal microtubule dynamics through GSK3 and its downstream substrate CRMP2. These findings reveal cellular and molecular mechanisms underlying brain-specific ANK3 disruption that may be related to its role in psychiatric illness.
Investigation of recombination-intense viral groups and their genes in the Earth’s virome
Authors: Meier-Kolthoff Jan P. , Uchiyama Jumpei , Yahara Hiroko , Paez-Espino David , Yahara Koji 
Published: July 2018

AbstractBacteriophages (phages), or bacterial viruses, are the most abundant and diverse biological entities that impact the global ecosystem. Recent advances in metagenomics have revealed their rampant abundance in the biosphere. A fundamental aspect of bacteriophages that remains unexplored in metagenomic data is the process of recombination as a driving force in evolution that occurs among different viruses within the same bacterial host. Here, we systematically examined signatures of recombination in every gene from 211 species-level viral groups in a recently obtained dataset of the Earth’s virome that contain corresponding information on the host bacterial species. Our study revealed that signatures of recombination are widespread (84%) among the diverse viral groups. We identified 25 recombination-intense viral groups, widely distributed across the viral taxonomy, and present in bacterial species living in the human oral cavity. We also revealed a significant inverse association between the recombination-intense viral groups and Type II restriction endonucleases, that could be effective in reducing recombination among phages in a cell. Furthermore, we identified recombination-intense genes that are significantly enriched for encoding phage morphogenesis proteins. Changes in the viral genomic sequence by recombination may be important to escape cleavage by the host bacterial immune systems.
L-tyrosine supplementation does not ameliorate skeletal muscle dysfunction in zebrafish and mouse models of dominant skeletal muscle α-actin nemaline myopathy
Authors: Messineo Adriana M. , Gineste Charlotte , Sztal Tamar E. , McNamara Elyshia L. , Vilmen Christophe , Ogier Augustin C. , Hahne Dorothee , Bendahan David , Laing Nigel G. , Bryson-Richardson Robert J. , Gondin Julien , Nowak Kristen J. 
Published: July 2018

AbstractL-tyrosine supplementation may provide benefit to nemaline myopathy (NM) patients, however previous studies are inconclusive, with no elevation of L-tyrosine levels in blood or tissue reported. We evaluated the ability of L-tyrosine treatments to improve skeletal muscle function in all three published animal models of NM caused by dominant skeletal muscle α-actin (ACTA1) mutations. Highest safe L-tyrosine concentrations were determined for dosing water and feed of wildtype zebrafish and mice respectively. NM TgACTA1D286G-eGFP zebrafish treated with 10 μM L-tyrosine from 24 hours to 6 days post fertilization displayed no improvement in swimming distance. NM TgACTA1D286G mice consuming 2% L-tyrosine supplemented feed from preconception had significant elevations in free L-tyrosine levels in sera (57%) and quadriceps muscle (45%) when examined at 6–7 weeks old. However indicators of skeletal muscle integrity (voluntary exercise, bodyweight, rotarod performance) were not improved. Additionally no benefit on the mechanical properties, energy metabolism, or atrophy of skeletal muscles of 6–7 month old TgACTA1D286G and KIActa1H40Y mice eventuated from consuming a 2% L-tyrosine supplemented diet for 4 weeks. Therefore this study yields important information on aspects of the clinical utility of L-tyrosine for ACTA1 NM.
Positive selection and climatic effects on MHC class II gene diversity in hares (Lepus capensis) from a steep ecological gradient
Authors: Awadi Asma , Ben Slimen Hichem , Smith Steve , Knauer Felix , Makni Mohamed , Suchentrunk Franz 
Published: July 2018

AbstractIn natural populations, allelic diversity of the major histocompatibility complex (MHC) is commonly interpreted as resulting from positive selection in varying spatiotemporal pathogenic landscapes. Composite pathogenic landscape data are, however, rarely available. We studied the spatial distribution of allelic diversity at two MHC class II loci (DQA, DQB) in hares, Lepus capensis, along a steep ecological gradient in North Africa and tested the role of climatic parameters for the spatial distribution of DQA and DQB proteins. Climatic parameters were considered to reflect to some extent pathogenic landscape variation. We investigated historical and contemporary forces that have shaped the variability at both genes, and tested for differential selective pressure across the ecological gradient by comparing allelic variation at MHC and neutral loci. We found positive selection on both MHC loci and significantly decreasing diversity from North to South Tunisia. Our multinomial linear models revealed significant effects of geographical positions that were correlated with mean annual temperature and precipitation on the occurrence of protein variants, but no effects of co-occurring DQA or DQB proteins, respectively. Diversifying selection, recombination, adaptation to local pathogenic landscapes (supposedly reflected by climate parameters) and neutral demographic processes have shaped the observed MHC diversity and differentiation patterns.
Experience of the signaller explains the use of social versus personal information in the context of sentinel behaviour in meerkats
Authors: Rauber R. , Manser M. B. 
Published: July 2018

AbstractTo maximise foraging opportunities while simultaneously avoiding predation, group-living animals can obtain personal information on food availability and predation risk and/or rely on social information provided by group members. Although mainly associated with low costs of information acquisition, social information has the potential to be irrelevant or inaccurate. In this study we use playbacks of individually distinct sentinel calming calls produced during sentinel behaviour, a form of coordinated vigilance behaviour, to show that meerkats (Suricata suricatta) discriminate between social information provided by different sentinels and adjust their personal vigilance behaviour according to the individual that is played back. We found that foraging group members acquired the lowest amounts of personal information when hearing social information provided by experienced individuals that act as sentinels most often in their group and littermates. Our study shows that social information can be flexibly used in the context of sentinel behaviour in order to optimize the trade-off between foraging and vigilance behaviours dependent on discrimination among signallers. We also provide novel evidence that the experience of sentinels rather than their age or dominance status is the main factor affecting the extent to which individuals use social information.