bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurements of the global 21-cm signal from the Cosmic Dawn
Authors: Bernardi Gianni 
Published: May 2018

AbstractThe sky-averaged (global) 21-cm signal is a very promising probe of the Cosmic Dawn, when the first luminous sources were formed and started to shine in a substantially neutral intergalactic medium. I here report on the status and early result of the Large-Aperture Experiment to Detect the Dark Age that focuses on observations of the global 21-cm signal in the 16 ≲ z ≲ 30 range.
Analysis of 21-cm tomographic data
Authors: Mellema Garrelt , Giri Sambit , Ghara Raghunath 
Published: May 2018

AbstractThe future SKA1-Low radio telescope will be powerful enough to produce tomographic images of the 21-cm signal from the Epoch of Reionization. Here we address how to identify ionized regions in such data sets, taking into account the resolution and noise levels associated with SKA1-Low. We describe three methods of which one, superpixel oversegmentation, consistently performs best.
Can Rates of Ocean Primary Production and Biological Carbon Export Be Related Through Their Probability Distributions?
Authors: Cael B. B. , Bisson Kelsey , Follett Christopher L. 
Published: May 2018

We describe the basis of a theory for interpreting measurements of two key biogeochemical fluxes—primary production by phytoplankton (p, μg C · L−1 · day−1) and biological carbon export from the surface ocean by sinking particles (f, mg C · m−2 · day−1)—in terms of their probability distributions. Given that p and f are mechanistically linked but variable and effectively measured on different scales, we hypothesize that a quantitative relationship emerges between collections of the two measurements. Motivated by the many subprocesses driving production and export, we take as a null model that large‐scale distributions of p and f are lognormal. We then show that compilations of p and f measurements are consistent with this hypothesis. The compilation of p measurements is extensive enough to subregion by biome, basin, depth, or season; these subsets are also well described by lognormals, whose log‐moments sort predictably. Informed by the lognormality of both p and f we infer a statistical scaling relationship between the two quantities and derive a linear relationship between the log‐moments of their distributions. We find agreement between two independent estimates of the slope and intercept of this line and show that the distribution of f measurements is consistent with predictions made from the moments of the p distribution. These results illustrate the utility of a distributional approach to biogeochemical fluxes. We close by describing potential uses and challenges for the further development of such an approach.
Van Allen Probes Observation of a Fundamental Poloidal Standing Alfvén Wave Event Related to Giant Pulsations
Authors: Takahashi Kazue , Claudepierre Seth G. , Rankin Robert , Mann Ian R. , Smith Charles W. 
Published: May 2018

AbstractThe Van Allen Probes‐A spacecraft observed an ∼9‐mHz ultralow‐frequency wave on 6 October 2012, at L ∼ 5.7, in the dawn sector, and very near the magnetic equator. The wave had a strong electric field that was initially stronger in the azimuthal component and later in the radial component, exhibited properties of a fundamental standing Alfvén wave, and was associated with giant pulsations observed on the ground near the magnetic field footprint of the spacecraft. The wave was accompanied by oscillations of the flux of energetic protons (jH+). The amplitude of
oscillations was large at equatorial pitch angles away from 90°, and the energy dependence of the phase and amplitude of the oscillations exhibited features consistent with drift resonance of ∼140‐keV protons with a westward‐propagating wave having an azimuthal wave number of ∼−40. The wave was detected when the spacecraft entered a region of an earthward gradient of the proton phase space density, in support of a theoretical prediction that such a gradient can drive fundamental poloidal waves.
A Statistical Model for Earthquake Recurrence Based on the Assimilation of Paleoseismicity, Historic Seismicity, and Instrumental Seismicity
Authors: Zöller Gert 
Published: May 2018

AbstractPaleoearthquakes and historic earthquakes are the most important source of information for the estimation of long‐term earthquake recurrence intervals in fault zones, because corresponding sequences cover more than one seismic cycle. However, these events are often rare, dating uncertainties are enormous, and missing or misinterpreted events lead to additional problems. In the present study, I assume that the time to the next major earthquake depends on the rate of small and intermediate events between the large ones in terms of a “clock change” model. Mathematically, this leads to a Brownian passage time distribution for recurrence intervals. I take advantage of an earlier finding that under certain assumptions the aperiodicity of this distribution can be related to the Gutenberg‐Richter b value, which can be estimated easily from instrumental seismicity in the region under consideration. In this way, both parameters of the Brownian passage time distribution can be attributed with accessible seismological quantities. This allows to reduce the uncertainties in the estimation of the mean recurrence interval, especially for short paleoearthquake sequences and high dating errors. Using a Bayesian framework for parameter estimation results in a statistical model for earthquake recurrence intervals that assimilates in a simple way paleoearthquake sequences and instrumental data. I present illustrative case studies from Southern California and compare the method with the commonly used approach of exponentially distributed recurrence times based on a stationary Poisson process.
Origin of Abyssal NW Atlantic Water Masses Since the Last Glacial Maximum
Authors: Pöppelmeier F. , Gutjahr M. , Blaser P. , Keigwin L. D. , Lippold J. 
Published: May 2018

AbstractThe notion of a shallow northern sourced intermediate water mass is a well evidenced feature of the Atlantic circulation scheme of the Last Glacial Maximum (LGM). However, recent observations from stable carbon isotopes (δ13C) at the Corner Rise in the deep northwest Atlantic suggested a significant contribution of a Northern Component Water mass to the abyssal northwest Atlantic basin that has not been described before. Here we test the hypothesis of this northern sourced water mass underlying the southern sourced glacial Antarctic Bottom Water by measuring the authigenic neodymium (Nd) isotopic composition from the same sediments from 5,010‐m water depth. Neodymium isotopes act as a semiconservative water mass tracer capable of distinguishing between Northern and Southern Component Waters at the northwest Atlantic. Our new Nd isotopic record resolves various water mass changes from the LGM to the early Holocene in agreement with existing Nd‐based reconstructions from across the west Atlantic Ocean. Especially pronounced are the Younger Dryas and Bølling‐Allerød with unprecedented changes in the Nd isotopic composition. For the LGM we found Nd isotopic evidence for a northern sourced water mass contributing to abyssal depths, thus being in agreement with previous δ13C data from Corner Rise. Overall, however, the deep northwest Atlantic was still dominated by southern sourced water, since we found signatures that are intermediate between northern and southern end member compositions. Furthermore, this new record indicates that C and Nd isotopes were partly decoupled, pointing to nonconservative behavior of one or more likely of both water mass proxies during the LGM.
Predicting Spatial Patterns in Precipitation Isotope (δ2H and δ18O) Seasonality Using Sinusoidal Isoscapes
Authors: Allen Scott T. , Kirchner James W. , Goldsmith Gregory R. 
Published: May 2018

AbstractUnderstanding how precipitation isotopes vary spatially and temporally is important for tracer applications. We tested how well month‐to‐month variations in precipitation δ18O and δ2H were captured by sinusoidal cycles, and how well spatial variations in these seasonal cycles could be predicted, across Switzerland. Sine functions representing seasonal cycles in precipitation isotopes explained between 47% and 94% of the variance in monthly δ18O and δ2H values at each monitoring site. A significant sinusoidal cycle was also observed in line‐conditioned excess. We interpolated the amplitudes, phases, and offsets of these sine functions across the landscape, using multiple linear regression models based on site characteristics. These interpolated maps, here referred to as a sinusoidal isoscape, reproduced monthly observations with prediction errors that were smaller than or similar to those of other isoscapes. Sinusoidal isoscapes are likely broadly useful because they concisely describe seasonal isotopic behavior and can be estimated efficiently from sparse or irregular data.
Transient Reactivation of a Deep‐Seated Landslide by Undrained Loading Captured With Repeat Airborne and Terrestrial Lidar
Authors: Booth Adam M. , McCarley Justin , Hinkle Jason , Shaw Susan , Ampuero Jean‐Paul , Lamb Michael P. 
Published: May 2018

AbstractLandslides reactivate due to external environmental forcing or internal mass redistribution, but the process is rarely documented quantitatively. We capture the three‐dimensional, 1‐m resolution surface deformation field of a transiently reactivated landslide with image correlation of repeat airborne lidar. Undrained loading by two debris flows in the landslide's head, rather than external forcing, triggered reactivation. After that loading, the lower 2 km of the landslide advanced by up to 14 m in 2 years before completely stopping. The displacement field over those 2 years implies that the slip surface gained 1 kPa of shear strength, which was likely accomplished by a negative dilatancy‐pore pressure feedback as material deformed around basal roughness elements. Thus, landslide motion can be decoupled from external environmental forcing in cases, motivating the need to better understand internal perturbations to the stress field to predict hazards and sediment fluxes as landscapes evolve.
The Effect of the Madden‐Julian Oscillation on the Mesospheric Migrating Diurnal Tide: A Study Using SD‐WACCM
Authors: Yang Chengyun , Smith Anne K. , Li Tao , Dou Xiankang 
Published: May 2018

AbstractThe response of the mesospheric migrating diurnal (DW1) tide to the Madden‐Julian oscillation (MJO) is investigated for the first time using a simulation from the Specified‐Dynamic Whole Atmosphere Community Climate Model (SD‐WACCM), which is driven by reanalysis data. Analysis shows that a significant connection exists between the MJO and the mesospheric DW1 tidal amplitude. During MJO phases 2 and 3, the convection anomalies are associated with enhancement in both the solar insolation absorption and latent heat release in the equatorial troposphere; these in turn lead to stronger DW1 forcing. Conversely, the forcing of DW1 by solar and latent heating in the troposphere is weaker during MJO phase 8. The difference of the tidal amplitude during the opposite MJO phases from the boreal winter mean state is ~15–20%. The parameterized gravity wave variations are found to have a significant impact on the DW1 tidal response in some phases of the MJO.
Strike‐Slip Motion Within the Yalu River Fault Zone, NE Asia: The Development of a Shear Continental Margin
Authors: Zhang Shuai , Zhu Guang , Liu Cheng , Li Yunjian , Su Nan , Xiao Shiye , Gu Chengchuan 
Published: May 2018

AbstractThe ca. 700‐km long Yalu River Fault Zone (YRFZ) is a major component of the NE striking strike‐slip fault system of the East Asia continental margin, which was active during the late Mesozoic. Despite its importance, the origin and timing of activity along the fault zone remain unclear. We present structural data that indicate that the NE striking YRFZ was initiated as a sinistral strike‐slip fault zone. Ductile, brittle‐ductile, and brittle structures are exposed along its length, with more ductile structures in the southwest. The shear belts and faults predominantly dip steeply to the southeast and have a minor reverse component of motion. Microstructures indicate deformation temperatures of ~300°C–500°C for the ductile region and ~200°C–300°C for the brittle‐ductile region. Inversion of fault slip data measured from brittle faults indicates that the sinistral motion was a result of N‐S compression. We present in situ zircon U‐Pb dating results for deformed and undeformed igneous rocks sampled from the ductile shear belts, indicating that sinistral faulting occurred between 146 and 131 Ma. This result correlates with the timing of a regional N‐S shortening event during the earliest Early Cretaceous. Our data, together with other published studies of this strike‐slip fault system, suggest that the East Asia shear margin was initiated at the beginning of the Early Cretaceous with the synchronous formation of a series of NE to NNE striking sinistral faults. This brief transpressive event along the shear margin was a result of the rapid, oblique subduction of the Izanagi Plate along a NNE trending trench.
A Comprehensive Analysis on the Stress Field and Seismic Anisotropy in Eastern Tibet
Authors: Yang Yihai , Liang Chuntao , Fang Lihua , Su Jinrong , Hua Qian 
Published: May 2018

AbstractWidespread rotations of maximum compressive stress in the upper crust are revealed in eastern Tibet by the focal mechanism stress inversion technique. Because of the good correlation with locations of folds, anticlines, and mountains in the region, the upper crustal stress variation is related to the lateral displacement of upper crust. To compare deformations in upper crust and upper mantle, we use SKS/SKKS splitting measurements to investigate the seismic anisotropy in eastern Tibet. The fast polarization directions subparallel to the strikes of faults in Chuandian fragment and southern boundary tectonic belt. This may indicate that the induced anisotropy mainly resulted from alignment of fault fabrics by strong shearing along strike‐slip faults, while the widespread stress rotations and systemic angular difference between upper crustal stress field and seismic anisotropy suggest that the decoupling of upper crustal deformation from middle‐lower crust by a series of detachments in the process of the crust thickening resulted from the obstruction of eastward expansion by Sichuan Basin.
Engineering modular intracellular protein sensor-actuator devices
Authors: Siciliano Velia , DiAndreth Breanna , Monel Blandine , Beal Jacob , Huh Jin , Clayton Kiera L , Wroblewska Liliana , McKeon AnneMarie , Walker Bruce D. , Weiss Ron 
Published: May 2018

AbstractUnderstanding and reshaping cellular behaviors with synthetic gene networks requires the ability to sense and respond to changes in the intracellular environment. Intracellular proteins are involved in almost all cellular processes, and thus can provide important information about changes in cellular conditions such as infections, mutations, or disease states. Here we report the design of a modular platform for intrabody-based protein sensing-actuation devices with transcriptional output triggered by detection of intracellular proteins in mammalian cells. We demonstrate reporter activation response (fluorescence, apoptotic gene) to proteins involved in hepatitis C virus (HCV) infection, human immunodeficiency virus (HIV) infection, and Huntington’s disease, and show sensor-based interference with HIV-1 downregulation of HLA-I in infected T cells. Our method provides a means to link varying cellular conditions with robust control of cellular behavior for scientific and therapeutic applications.
Neural encoding and production of functional morphemes in the posterior temporal lobe
Authors: Lee Daniel K. , Fedorenko Evelina , Simon Mirela V. , Curry William T. , Nahed Brian V. , Cahill Dan P. , Williams Ziv M. 
Published: May 2018

AbstractMorphemes are the smallest meaning-carrying units in human language, and are among the most basic building blocks through which humans express specific ideas and concepts. By using time-resolved cortical stimulations, neural recordings, and focal lesion evaluations, we show that inhibition of a small cortical area within the left dominant posterior–superior temporal lobe selectively impairs the ability to produce appropriate functional morphemes but does not distinctly affect semantic and lexical retrieval, comprehension, or articulation. Additionally, neural recordings within this area reveal the localized encoding of morphological properties and their planned production prior to speech onset. Finally, small lesions localized to the gray matter in this area result in a selective functional morpheme-production deficit. Collectively, these findings reveal a detailed division of linguistic labor within the posterior–superior temporal lobe and suggest that functional morpheme processing constitutes an operationally discrete step in the series of computations essential to language production.
Quantifying compressive forces between living cell layers and within tissues using elastic round microgels
Authors: Mohagheghian Erfan , Luo Junyu , Chen Junjian , Chaudhary Gaurav , Chen Junwei , Sun Jian , Ewoldt Randy H. , Wang Ning 
Published: May 2018

AbstractIncreasing evidence shows that mechanical stresses are critical in regulating cell functions, fate, and diseases. However, no methods exist that can quantify isotropic compressive stresses. Here we describe fluorescent nanoparticle-labeled, monodisperse elastic microspheres made of Arg-Gly-Asp-conjugated alginate hydrogels (elastic round microgels, ERMGs). We generate 3D displacements and calculate strains and tractions exerted on an ERMG. Average compressive tractions on an ERMG are 570 Pa within cell layers and 360 Pa in tumor-repopulating cell (TRC) colonies grown in 400-Pa matrices. 3D compressive tractions on a 1.4-kPa ERMG are applied by surrounding cells via endogenous actomyosin forces but not via mature focal adhesions. Compressive stresses are substantially heterogeneous on ERMGs within a uniform cell colony and do not increase with TRC colony sizes. Early-stage zebrafish embryos generate spatial and temporal differences in local normal and shear stresses. This ERMG method could be useful for quantifying stresses in vitro and in vivo.
CO2-sensitive tRNA modification associated with human mitochondrial disease
Authors: Lin Huan , Miyauchi Kenjyo , Harada Tai , Okita Ryo , Takeshita Eri , Komaki Hirofumi , Fujioka Kaoru , Yagasaki Hideki , Goto Yu-ichi , Yanaka Kaori , Nakagawa Shinichi , Sakaguchi Yuriko , Suzuki Tsutomu 
Published: May 2018

AbstractIt has been generally thought that tRNA modifications are stable and static, and their frequencies are rarely regulated. N6-threonylcarbamoyladenosine (t6A) occurs at position 37 of five mitochondrial (mt-)tRNA species. We show that YRDC and OSGEPL1 are responsible for t6A37 formation, utilizing L-threonine, ATP, and CO2/bicarbonate as substrates. OSGEPL1-knockout cells exhibit respiratory defects and reduced mitochondrial translation. We find low level of t6A37 in mutant mt-tRNA isolated from the MERRF-like patient’s cells, indicating that lack of t6A37 results in pathological consequences. Kinetic measurements of t6A37 formation reveal that the Km value of CO2/bicarbonate is extremely high (31 mM), suggesting that CO2/bicarbonate is a rate-limiting factor for t6A37 formation. Consistent with this, we observe a low frequency of t6A37 in mt-tRNAs isolated from human cells cultured without bicarbonate. These findings indicate that t6A37 is regulated by sensing intracellular CO2/bicarbonate concentration, implying that mitochondrial translation is modulated in a codon-specific manner under physiological conditions.
Reconstruction of the diapsid ancestral genome permits chromosome evolution tracing in avian and non-avian dinosaurs
Authors: O’Connor Rebecca E. , Romanov Michael N. , Kiazim Lucas G. , Barrett Paul M. , Farré Marta , Damas Joana , Ferguson-Smith Malcolm , Valenzuela Nicole , Larkin Denis M. , Griffin Darren K. 
Published: May 2018

AbstractGenomic organisation of extinct lineages can be inferred from extant chromosome-level genome assemblies. Here, we apply bioinformatic and molecular cytogenetic approaches to determine the genomic structure of the diapsid common ancestor. We then infer the events that likely occurred along this lineage from theropod dinosaurs through to modern birds. Our results suggest that most elements of a typical ‘avian-like’ karyotype (40 chromosome pairs, including 30 microchromosomes) were in place before the divergence of turtles from birds ~255 mya. This genome organisation therefore predates the emergence of early dinosaurs and pterosaurs and the evolution of flight. Remaining largely unchanged interchromosomally through the dinosaur–theropod route that led to modern birds, intrachromosomal changes nonetheless reveal evolutionary breakpoint regions enriched for genes with ontology terms related to chromatin organisation and transcription. This genomic structure therefore appears highly stable yet contributes to a large degree of phenotypic diversity, as well as underpinning adaptive responses to major environmental disruptions via intrachromosomal repatterning.
Controlling evanescent waves using silicon photonic all-dielectric metamaterials for dense integration
Authors: Jahani Saman , Kim Sangsik , Atkinson Jonathan , Wirth Justin C. , Kalhor Farid , Noman Abdullah Al , Newman Ward D. , Shekhar Prashant , Han Kyunghun , Van Vien , DeCorby Raymond G. , Chrostowski Lukas , Qi Minghao , Jacob Zubin 
Published: May 2018

AbstractUltra-compact, densely integrated optical components manufactured on a CMOS-foundry platform are highly desirable for optical information processing and electronic-photonic co-integration. However, the large spatial extent of evanescent waves arising from nanoscale confinement, ubiquitous in silicon photonic devices, causes significant cross-talk and scattering loss. Here, we demonstrate that anisotropic all-dielectric metamaterials open a new degree of freedom in total internal reflection to shorten the decay length of evanescent waves. We experimentally show the reduction of cross-talk by greater than 30 times and the bending loss by greater than 3 times in densely integrated, ultra-compact photonic circuit blocks. Our prototype all-dielectric metamaterial-waveguide achieves a low propagation loss of approximately 3.7±1.0 dB/cm, comparable to those of silicon strip waveguides. Our approach marks a departure from interference-based confinement as in photonic crystals or slot waveguides, which utilize nanoscale field enhancement. Its ability to suppress evanescent waves without substantially increasing the propagation loss shall pave the way for all-dielectric metamaterial-based dense integration.