bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Neuropsychological Syndrome of Agenesis of the Corpus Callosum
Authors: Brown Warren S. , Paul Lynn K. 
Published: January 2019

AbstractBackground: Agenesis of the corpus callosum (AgCC) involves congenital absence of all or part of the corpus callosum. Because the disorder can only be firmly diagnosed via neuroradiology, it has a short research history, and only recently has the cognitive syndrome become clear. Purpose: Our purpose is to review the primary deficits in AgCC that constitute the core syndrome. Conclusions: The cores syndrome includes: (1) reduced interhemispheric transfer of sensory-motor information; (2) reduced cognitive processing speed; and (3) deficits in complex reasoning and novel problem-solving. These domains do not appear to reflect different neuroanatomical abnormalities, but rather different domains of expression of reduced interhemispheric communication from callosal absence. Implications: These core deficits are expressed across various domains of cognitive, behavioral, and social functioning. The impact of these deficits varies across development and may be moderated by individual factors such as co-occurrence of other neurodevelopmental conditions, general intellectual capacity, and environmental support. (JINS, 2019, 25, 324–330)
Revealing Short GRB Jet Structure and Dynamics with Gravitational Wave Electromagnetic Counterparts
Authors: Lamb Gavin P. , Kobayashi Shiho 
Published: January 2019

AbstractCompact object mergers are promising candidates for the progenitor system of short gamma-ray bursts (GRBs). Using gravitational wave (GW) triggers to identify a merger, any electromagnetic (EM) counterparts from the jet can be used to constrain the dynamics and structure of short GRB jets. GW triggered searches could reveal a hidden population of optical transients associated with the short-lived jets from the merger object. If the population of merger-jets is dominated by low-Lorentz-factors, then a GW triggered search will reveal the on-axis orphan afterglows from these failed GRBs. By considering the EM counterparts from a jet, with or without the prompt GRB, the jet structure and dynamics can be constrained. By modelling the afterglow of various jet structures with viewing angle, we provide observable predictions for the on- and off- axis EM jet counterparts. The predictions provide an indication for the various features expected from the proposed jet structure models.
Observations of GW170817 by DESGW and the DECam GW-EM Collaboration
Authors: Annis James 
Published: January 2019

AbstractOn August 17, 2017 LIGO/Virgo detected a binary neutron star via gravitational waves. We observed 70 sq-degrees in the LIGO/Virgo spatial localization with the DECam on the 4m Blanco telescope covering 80% of the final map. Our group independently discovered an optical counterpart in NGC 4993. We searched our entire imaged region: the object in NGC 4993 was the only viable candidate. Our observations of NGC4993 show complicated morphology but simple star formation history. Our x-ray and radio observations indicate an off-axis jet as afterglow. Our high-cadence optical and infrared spectra show a source that must be described by at least two components, one of which is dominated by the r-process nucleosynthesis elements characteristic of a kilonova. Our modeling of the light curve demonstrates such a model in which 0.05 M⊙ of material is ejected from the system. Finally, we discuss the first standard siren measurement of H0.
Reanalysis of LIGO black-hole coalescences with alternative prior assumptions
Authors: Gerosa Davide , Vitale Salvatore , Haster Carl-Johan , Chatziioannou Katerina , Zimmerman Aaron 
Published: January 2019

AbstractWe present a critical reanalysis of the black-hole binary coalescences detected during LIGO’s first observing run under different Bayesian prior assumptions. We summarize the main findings of Vitale et al. (2017) and show additional marginalized posterior distributions for some of the binaries’ intrinsic parameters.These findings were presented at IAU Symposium 338, held on October 16-19, 2017 in Baton Rouge, LA, USA.
Supermassive Black Hole Binary Candidates from the Pan-STARRS1 Medium Deep Survey
Authors: Liu Tingting , Gezari Suvi 
Published: January 2019

AbstractWe conducted a systematic search for periodically varying quasars, which are predicted manifestations of sub-pc supermassive black hole binaries (SMBHBs), in the Pan-STARRS1 Medium Deep Survey (PS1 MDS). Since the normal variability of quasars can also mimic periodicity over a small number of cycles, we have extended the temporal baseline by monitoring the candidates with the Discovery Channel Telescope and the Las Cumbres Observatory telescopes. We have also adopted a more rigorous method to evaluate the significance of the periodic candidates, by considering in the light curves a “red noise” background modeled as the Damped Random Walk process. While none of the candidates can be resolved by the current pulsar timing arrays (PTAs) as individual gravitational wave sources, the Large Synoptic Survey Telescope is capable of finding more periodic candidates, some of which are likely to be detected by the PTA experiment with the Square Kilometre Array.
On the host galaxy properties of stellar binary black hole mergers
Authors: Lu Youjun , Cao Liang , Zhao Yuetong 
Published: January 2019

AbstractWe report our investigations on the host galaxy properties of stellar binary black holes (SBBHs) by implementing simple recipes for SBBH formation and merger into cosmological galaxy formation model. If the time delay between SBBH formation and merger ranges from Gyr to the Hubble time, SBBH mergers at redshift z < 0.3 occur preferentially in big galaxies with stellar mass M* > 2 × 1010M⊙ and metallicities Z peaking around ~0.6Z⊙. However, the host galaxy stellar mass distribution of heavy SBBH mergers (with total black hole mass >50M⊙) is bimodal with one peak at ~109M⊙ and the other peak at ~2 × 1010M⊙. The contribution fraction from metal-poor host galaxies (Z < 0.2Z⊙) to heavy mergers is much larger than that to less heavy mergers. If SBBHs were formed in the early universe, their mergers detected at z < 0.3 occur preferentially in even more massive galaxies with M* > 3 × 1010M⊙ and in galaxies with metallicities mostly >0.2Z⊙ and peaking at Z ~ 0.6Z⊙.
Cosmology with Gravitational Waves in DES and LSST
Authors: Herner Kenneth , Soares-Santos Marcelle , Annis James 
Published: January 2019

AbstractMotivated by the prospect of the wealth of data arising from the inauguration of the era of gravitational wave detection by ground-based interferometers the DES collaboration, in partnership with members of the LIGO collaboration and members of the astronomical community at large, have established a research program to search for their optical counterparts and to explore their use as cosmological probes. In this talk we present the status of our program and discuss prospects for establishing this new probe as part of the portfolio of the Dark Energy research program in the future, in particular for the next generation survey, LSST.
Environmental Significance of the Chemical Composition of Sediments in Groundwater‐Recharged Lakes of the Badain Jaran Desert, NW China
Authors: Li Zhuolun , Chen Qiujie , Zhang Cheng , Yu Qiangjing , Dong Shipei , Zhao Liqiang , Wang Nai'ang 
Published: January 2019

AbstractFor lakes in desert hinterlands that are not recharged by river runoff, sediment is input solely by wind transport; however, the mechanisms that control the spatial variations in geochemical characteristics of sediments in such lakes remain unclear. Moreover, it remains uncertain whether some element ratios can be used as proxies for environmental characteristics. In this study, 100 surface sediment samples were collected from five lakes in the hinterland of the Badain Jaran Desert, NW China, and examined for their major, trace and rare earth element contents and mineral assemblages. Chemical composition and mineral components of the sediments differed significantly between lakes with different total dissolved solids (TDS). Geochemical characteristics of the lake sediments and their spatial variations are influenced by eolian sands, saline minerals, and sediment sorting. Eolian sands dominate the immobile and nonsoluble elements, whereas authigenic minerals are important in influencing variations in the mobile and soluble elements. Sediment sorting is reflected in the spatial variation of the sediment chemical composition. The positive relationship between the SiO2/Ti of sediment and lake area indicates that changes in the SiO2/Ti ratio can reveal approximate lake area. The Na2O/K2O ratio in sediments can reveal the TDS of salt lakes more effectively than can the Rb/Sr ratio. However, the key factors and mechanisms governing the chemical composition of sediments at different brine evolution stages vary among lakes with different TDS levels, which should be carefully considered when interpreting the environmental significance of the chemical composition as a proxy for paleoenviroment change.
Premonsoon/Postmonsoon Bay of Bengal Tropical Cyclones Intensity: Role of Air‐Sea Coupling and Large‐Scale Background State
Authors: Neetu S. , Lengaigne M. , Vialard J. , Samson G. , Masson S. , Krishnamohan K. S. , Suresh I. 
Published: January 2019

AbstractThe densely populated Bay of Bengal (BoB) rim witnesses the deadliest tropical cyclones (TCs) globally, before and after the summer monsoon. Previous studies indicated that enhanced salinity and reduced thermal stratification reduce cooling under BoB TCs after the monsoon, suggesting that air‐sea coupling may favor stronger TCs during that season. Using observations and simulations from a one fourth degree regional ocean‐atmosphere model, we show that BoB TCs are stronger before the monsoon due to a more favorable large‐scale background state (less vertical wind shear and higher sea surface temperature). Air‐sea coupling however alleviates this background state influence, by reducing the number of premonsoon intense TCs, because of larger cooling and reduced upward enthalpy fluxes below TCs during that season. As the impact of air‐sea interactions on BoB TCs is largest for intense TCs, it should be further investigated for Category 3 and above TCs, which are not reproduced at one fourth degree resolution.
Inertia Influences Pelagic Sargassum Advection and Distribution
Authors: Brooks Maureen T. , Coles Victoria J. , Coles William C. 
Published: January 2019

AbstractThe effect of inertia (resistance to a change in velocity of buoyant finite‐sized objects) on the advection of pelagic Sargassum, a macroalgae, is a function of the size and density of natural Sargassum rafts. Here we present observations of Sargassum density and an approach for estimating an effective radius of Sargassum rafts from remote‐sensing observations. This allows the existing theoretical framework for Lagrangian modeling of inertial effects on spherical particles to be applied to Sargassum. Accounting for inertia yields up to a 20% increase in Sargassum export from the Sargasso Sea southward and provides a return pathway to the tropics that may be important to maintaining a self‐sustaining population. Resolving inertial effects also leads to increases in retention in the Gulf of Mexico and Caribbean Sea, where Sargassum inundation events are increasingly common. Including inertial effects in models of Sargassum advection could improve predictions of these events.
Local Generation of High‐Frequency Plasmaspheric Hiss Observed by Van Allen Probes
Authors: He Zhaoguo , Chen Lunjin , Liu Xu , Zhu Hui , Liu Si , Gao Zhonglei , Cao Yong 
Published: January 2019

AbstractThe generation of a high‐frequency plasmaspheric hiss (HFPH) wave observed by Van Allen Probes is studied in this letter for the first time. The wave has a moderate power spectral density (∼10−6 nT2/Hz), with a frequency range extended from 2 to 10 kHz. The correlated observations of waves and particles indicate that HFPH is associated with the enhancement of electron flux during the substorm on 6 January 2014. Calculations of the wave linear growth rate driven by the fitted electron phase space density show that the electron distribution after the substorm onset is efficient for the HFPH generation. The energy of the contributing electrons is about 1–2 keV, which is consistent with the observation. These results support that the observed HFPH is likely to be generated locally inside the plasmasphere due to the instability of injected kiloelectron volt electrons.
A Numerical Model for the Effect of Permeability Change on Faulting During Fluid Injection
Authors: Zhang Xi , Jeffrey Robert G. , He Changrong 
Published: January 2019

AbstractSlip and slip zone development during constant‐rate fluid injection into a permeable fault in an infinite, impermeable elastic rock is studied here numerically using a hydromechanical fracture model. The interplay of slip zone growth and fault dilatancy is assumed to be affected by linear slip weakening of frictional strength and slip‐induced dilation. The discretization error is minimized by using element sizes based on a mesh sensitivity study to obtain accurate slipping and pressurized lengths. Comparisons with published results for large and zero fault permeability cases demonstrate the validity of the numerical results. Dimensional analysis is used to identify five parameters that control slip development, including the slip‐induced dilatancy factor, initial fault permeability, the product of fluid viscosity and injection rate, the background shear to normal stress ratio, and the residual coefficient of friction. Conditions leading a quasi‐static stable slip to either continue as stable aseismic slip or accelerate are discussed. Acceleration of slip occurs on less permeable faults characterized by a hybrid tensile‐shear fracture subject to higher pressure, while prolonged aseismic slip occurs along a more permeable fault subject to lower pressure. During long‐duration aseismic slip the pressure varies slightly around the value that equalizes the fault shear strength and the background shear stress. A permeability perturbation in the form of a sinusoidal fault aperture distribution does not change the tendency of the slip to be slow and stable. Like preexisting permeability, slip‐induced dilation responses play a role in limiting pressure level and extending the slow slip period.
Azimuthal Seismic Anisotropy of 70‐Ma Pacific‐Plate Upper Mantle
Authors: Mark H. F. , Lizarralde D. , Collins J. A. , Miller N. C. , Hirth G. , Gaherty J. B. , Evans R. L. 
Published: January 2019

AbstractPlate formation and evolution processes are predicted to generate upper mantle seismic anisotropy and negative vertical velocity gradients in oceanic lithosphere. However, predictions for upper mantle seismic velocity structure do not fully agree with the results of seismic experiments. The strength of anisotropy observed in the upper mantle varies widely. Further, many refraction studies observe a fast direction of anisotropy rotated several degrees with respect to the paleospreading direction, suggesting that upper mantle anisotropy records processes other than 2‐D corner flow and plate‐driven shear near mid‐ocean ridges. We measure 6.0 ± 0.3% anisotropy at the Moho in 70‐Ma lithosphere in the central Pacific with a fast direction parallel to paleospreading, consistent with mineral alignment by 2‐D mantle flow near a mid‐ocean ridge. We also find an increase in the strength of anisotropy with depth, with vertical velocity gradients estimated at 0.02 km/s/km in the fast direction and 0 km/s/km in the slow direction. The increase in anisotropy with depth can be explained by mechanisms for producing anisotropy other than intrinsic effects from mineral fabric, such as aligned cracks or other structures. This measurement of seismic anisotropy and gradients reflects the effects of both plate formation and evolution processes on seismic velocity structure in mature oceanic lithosphere, and can serve as a reference for future studies to investigate the processes involved in lithospheric formation and evolution.
Klinkenberg Effect and Effective Pressure for Gas Permeability of Tight Sandstones
Authors: Xiao Wenlian , Bernabé Yves , Evans Brian , Mok Ulrich , Zhao Jinzhou , Ren Xiyao , Chen Meng 
Published: January 2019

AbstractGas permeability kg of tight sandstones was measured while cycling pore pressure, Pf, and confining pressure, Pc, using two different procedures. First, we cycled the pore pressure from a minimum value close to atmospheric pressure to a maximum one slightly lower than Pc, while keeping the Pc constant. Second, Pf and Pc were simultaneously varied so as to keep the difference, Pc − Pf, constant. Significant effects owing to slip flow were observed when the gas pressure was lower than about 5 MPa. Klinkenberg plots showed that, under constant Pc, gas permeability kg decreased linearly for high values of 1/Pf, reached a minimum and then sharply increased as 1/Pf approached zero. Under constant Pc − Pf, kg again decreased linearly in the high limit of 1/Pf and showed additional decrease in the low 1/Pf limit. The linear segments in both procedures indicate that kg in tight sandstones was subject to slip flow at low values of Pf, while the curved segments revealed the sensitivity of permeability to effective pressure when Pf became comparable in magnitude to confining pressure. The effective pressure coefficient α was estimated and generally appeared to be a well‐defined decreasing function of the pressure difference Pc − Pf. We modified the Walsh permeability model for fissured rocks to include slip flow effects and obtained satisfactory fits to the experimental data for the samples with the lowest porosities and the highest pressure sensitivities. This observation suggests that the intrinsic permeability of these rocks was controlled by intergranular and/or intragranular crack‐like pores.
Long‐Lasting Evolution of Layer 2A in the Western South Atlantic: Evidence for Low‐Temperature Hydrothermal Circulation in Old Oceanic Crust
Authors: Kardell Dominik A. , Christeson Gail L. , Estep Justin D. , Reece Robert S. , Carlson Richard L. 
Published: January 2019

AbstractPrevious seismic studies suggest that hydrothermal processes are active only within young oceanic crust (<10–16 Ma). However, differences between measured and predicted heat flow at the ocean floor indicate that hydrothermal fluids may be transporting heat advectively in crust up to ages of 65 Ma. We report on seismic velocities of 0–71 Ma slow to intermediate spreading rate upper crust in the western South Atlantic. Thirteen high‐resolution 2‐D velocity models were built using traveltime tomography on downward continued streamer data acquired during the Crustal Reflectivity Experiment Southern Transect. In the Crustal Reflectivity Experiment Southern Transect area, velocities at the top of seismic layer 2A increase rapidly from ~2.4 km/s at 0 Ma to ~4.2 km/s at 6 Ma and then undergo a more gradual increase to ~4.9 km/s at 58 Ma. These new results resolve the long‐standing debate about the duration of interaction between ocean crust and seawater, providing seismic evidence for hydrothermal circulation continuing to crustal ages predicted by heat flow studies. Seismic layer 2B does not show a systematic off‐axis velocity trend but has an average value of 5.15 km/s. We interpret this result to indicate that the hydrothermal system becomes too shallow to affect the physical properties of layer 2B shortly after crustal accretion. Upper crustal heterogeneity in ridge‐parallel profile orientation is more pronounced for crust accreted at slow spreading rates, compared to intermediate rates. This result is consistent with shorter magmatic segments at slower spreading rates, increasing the frequency of tectonic and magmatic accretion alternately occurring along the ridge.
Shallow and Deep Eastern Boundary Currents in the South Atlantic at 34.5°S: Mean Structure and Variability
Authors: Kersalé Marion , Perez Renellys C. , Speich Sabrina , Meinen Christopher S. , Lamont Tarron , Le Hénaff Matthieu , van den Berg Marcel A. , Majumder Sudip , Ansorge Isabelle J. , Dong Shenfu , Schmid Claudia , Terre Thierry , Garzoli Silvia L. 
Published: January 2019

AbstractThe first in situ continuous full‐water‐column observations of the eastern boundary currents (EBCs) at 34.5°S in the South Atlantic are obtained using 23 months of data from a line of Current and Pressure recording Inverted Echo Sounders (CPIES) spanning the Cape Basin. The CPIES are used to evaluate the mean structure of the EBC, the associated water masses, and the volume transport variability. The estimated northward time‐mean Benguela Current absolute geostrophic transport is 24 Sv, with a temporal standard deviation of 17 Sv. Beneath this current the time‐mean transport is southward, indicating the presence of a deep‐EBC (DEBC), with a time‐mean transport of 12 Sv, and a standard deviation of 17 Sv. Offshore of these currents, the shallow and deep flows are more variable with weak time means, likely influenced by Agulhas Rings transiting through the region. Hydrographic data collected along the CPIES line demonstrate that the DEBC is carrying recently ventilated North Atlantic Deep Water, as it flows along the continental slope. This is consistent with a previously hypothesized interior pathway bringing recently ventilated North Atlantic Deep Water from the Deep Western Boundary Current across the Atlantic to the Cape Basin. The observations further indicate that much of the DEBC must recirculate within the basin. Spectral analyses of the shallow and deep EBC transport time series demonstrate that the strongest variability occurs on timescales ranging from 30 to 90 days, associated with the propagation of Agulhas Rings.
A Wedge Mechanism for Summer Surface Water Inflow Into the Ross Ice Shelf Cavity
Authors: Malyarenko A. , Robinson N. J. , Williams M. J. M. , Langhorne P. J. 
Published: January 2019

AbstractOcean heat supply to ice shelves has a significant impact on the long‐term evolution of ice shelves. Intrusions of warm surface waters into the frontal region of the cavity, known as “Mode 3” circulation, are capable of melting the ice shelf base. However, ablation of the vertical walls of the ice shelf front has, to date, received little attention. Here we propose a mechanism for Mode 3 circulation that is aided by ice shelf front ablation: Direct contact of warm Antarctic Surface Water with the ice wall generates meltwater that buoyantly ascends the vertical face and leads to formation of a “wedge” of fresher water immediately adjacent to the wall. This wedge, which thins with distance from the ice shelf front, allows isopycnals to curve gently downward, creating an efficient conduit by which surface waters moved by other forces such as tidal flow and eddies enter an ice shelf cavity with minimal mixing. Here we use new and existing observational data from the Ross Sea and the Ross Ice Shelf cavity to demonstrate the existence of the wedge. Our analysis and a review of the literature suggest that the freshwater wedge structure is a pervasive feature of the Western Ross Sea in summer and enhances other inflow mechanisms.