bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glacier Energy and Mass Balance in the Inland Tibetan Plateau: Seasonal and Interannual Variability in Relation to Atmospheric Changes
Authors: Li Shenghai , Yao Tandong , Yang Wei , Yu Wusheng , Zhu Meilin 
Published: June 2018

AbstractThe Tibetan glaciers are greatly affected by the circulations of the westerlies and the Indian summer monsoon (ISM), but the mechanisms remain to be elucidated. In this project, we investigated the surface energy and mass balance of the Qiangtang No.1 Glacier in the inland Tibetan Plateau. Combining 4‐year mass balance and meteorological records near the equilibrium line altitude with an energy‐based mass balance model, we found that the meteorological conditions, which determined the glacier surface ablation and mass accumulation, are critically linked to changes in the intensity of the westerlies and the ISM. The 4‐year mass balance comparisons demonstrated that the enhancement of the ISM in June and July, especially June, greatly increases the mass accumulation but inhibits the glacial ablation in the melt season, shifting the mass balance in a positive direction. Moreover, the occurrence of the westerlies enhancement interrupts the dominance of the ISM in the melt season. The intensified westerlies in the early melt season (June) could not only reduce the mass accumulation but also enhance the mass loss in the following months. In addition, the enhancement of the westerlies in the main melt season (July) could also greatly influence the local meteorological conditions, with lower temperatures and humidity but higher wind speeds. Such meteorological changes significantly reduce glacial ablation because more energy is consumed by sublimation and/or evaporation, rather than surface melting. These findings will enhance our understanding of the mechanisms underlying glacier changes and their relationships with the westerlies and the ISM in the inland Tibetan Plateau.
Decelerating Autumn CO2 Release With Warming Induced by Attenuated Temperature Dependence of Respiration in Northern Ecosystems
Authors: Liu Dan , Piao Shilong , Wang Tao , Wang Xuhui , Wang Xiaoyi , Ding Jinzhi , Ciais Philippe , Peñuelas Josep , Janssens Ivan 
Published: June 2018

AbstractFeedbacks from the carbon cycle in boreal and arctic ecosystems can significantly affect climate change, but the effects of climate change on the high‐latitude carbon cycle during the dormant period remain uncertain. By analyzing the long‐term atmospheric CO2 concentration record from Point Barrow in Alaska, we show that warming significantly boosts net CO2 release in autumn over the period 1974–2014. But this warming‐stimulated effect has been attenuated since 1997. This deceleration of net CO2 release with warming is ascribed to the attenuation in respiration response to temperature rather than changing relationship between temperature and productivity or changes in atmospheric transport, fossil fuel emissions, or air‐sea CO2 exchanges. The attenuated respiration response is likely due to decoupling between temperature and plant‐derived carbon inputs to soil for decomposition. Contrary to previous suggestions, warming no longer results in a higher autumn net CO2 release.
Direct Visualization of Individual Aromatic Compound Structures in Low Molecular Weight Marine Dissolved Organic Carbon
Authors: Fatayer Shadi , Coppola Alysha I. , Schulz Fabian , Walker Brett D. , Broek Taylor A. , Meyer Gerhard , Druffel Ellen R. M. , McCarthy Matthew , Gross Leo 
Published: June 2018

AbstractDissolved organic carbon (DOC) is the largest pool of exchangeable organic carbon in the ocean. However, less than 10% of DOC has been molecularly characterized in the deep ocean to understand DOC's recalcitrance. Here we analyze the radiocarbon (14C) depleted, and presumably refractory, low molecular weight (LMW) DOC from the North Central Pacific using atomic force microscopy to produce the first atomic‐resolution images of individual LMW DOC molecules. We evaluate surface and deep LMW DOC chemical structures in the context of their relative persistence and recalcitrance. Atomic force microscopy resolved planar structures with features similar to polycyclic aromatic compounds and carboxylic‐rich alicyclic structures with less than five aromatic carbon rings. These compounds comprise 8% and 20% of the measurable molecules investigated in the surface and deep, respectively. Resolving the structures of individual DOC molecules represents a step forward in molecular characterization of DOC and in understanding its long‐term stability.
Internal Erosion Controls Failure and Runout of Loose Granular Deposits: Evidence From Flume Tests and Implications for Postseismic Slope Healing
Authors: Hu Wei , Scaringi Gianvito , Xu Qiang , Huang Runqiu 
Published: June 2018

AbstractLandslides in granular soils can be highly hazardous when exhibiting flow‐like behavior. The extensive mass wasting associated with the 2008 Mw = 7.9 Wenchuan earthquake (China) left several cubic kilometers of loose granular material deposited along steep slopes and in low‐order channels. Rainfall‐triggered remobilization of these deposits evolved often into catastrophic flow‐like landslides. Ten years after the earthquake, most of the deposits are still in place but landslide rates have decreased significantly. Internal erosion‐induced grain coarsening is one possible process producing this decrease. Through experiments on loose artificial slopes we demonstrate the major role of the internally erodible small grains in triggering failure and fluidization and producing grain coarsening. Under the same hydraulic boundary, if the erodible fraction is removed or reduced, the loose deposits remain stable or fail without fluidizing. Our results provide an experimental evidence to the patterns of sediment export and debris flows observed in nature after a strong earthquake.
Limits on Dione's Activity Using Cassini/CIRS Data
Authors: Howett Carly J. A. , Spencer John R. , Hurford Terry , Verbiscer Anne , Segura Marcia 
Published: June 2018

AbstractWe use nighttime Cassini Composite Infrared Spectrometer (CIRS) data to look for discrete regions of elevated nighttime temperatures indicative of endogenic activity on Dione's surface. This is achieved by producing low latitude and midlatitude (less than 60°) maps of Dione's nighttime surface temperature, derived from 10 to 1,100‐cm−1 CIRS data. The surface temperatures observed do not show evidence of any small discrete regions of elevated nighttime temperatures and are comparable to temperatures predicted by a passive thermophysical model of Dione's surface. Thus, we conclude that no evidence for activity exists on Dione at midlatitude to low latitude. Using the derived surface temperature maps, we set upper limits for the temperature at which a 50‐, 100‐, or 200‐km2 hot spot would remain undetected by this study. We find the mean temperature of such a hot spot would be 117.1 ± 47.2 K (−249 F), 104.8 ± 27.7 K (−272 F), and 95.4 ± 19.5 K (−288 F) for a 50‐, 100‐, and 200‐km2 hot spot, respectively, corresponding to endogenic emission of 1.07, 0.68, and 0.47 GW.
A Robust Increase of the Intraseasonal Periodic Behavior of the Precipitation and Eddy Kinetic Energy in a Warming Climate
Authors: Wang Lei , Lu Jian , Kuang Zhiming 
Published: June 2018

AbstractPrecipitation and storm track activity in the Southern Hemisphere feature a remarkable 20 to 30‐day periodicity known as baroclinic annular mode. In climate model projections following the representative concentration pathway 8.5 scenario, this work finds a robust increase of intraseasonal variability of the precipitation and density‐weighted eddy kinetic energy at the 20–30 day frequency range by 25% and 20%, respectively, in austral summer toward the end of the century, despite small changes in seasonal‐mean quantities at corresponding latitudes. These results suggest that a warming climate can feature a stronger dynamical organization of the 20–30 day periodicity by the moist baroclinic waves. For austral winter, the weak 20–30 day periodicity in the current climate becomes a prominent mode of quasiperiodic variability toward the end of the century in these model projections. This work identifies both the increase of diabatic heating and the enhancements of the waveguide effects as candidate mechanisms.
Electromagnetic Thermal Noise in Upper‐Hybrid Frequency Range
Authors: Yoon Peter H. , Hwang Junga , López Rodrigo A. , Kim Sunjung , Lee Jaejin 
Published: June 2018

AbstractThe inner magnetosphere including the radiation belt and ring current environment is replete with high‐frequency fluctuations with peak intensity occurring near upper‐hybrid frequency and/or multiple harmonic electron cyclotron frequencies above and below the upper‐hybrid frequency. Past and contemporary spacecraft missions, including the Van Allen Probes, were designed to detect the electric field spectrum only for these high‐frequency fluctuations. Making use of the recently formulated generalized theory of electromagnetic spontaneous emission in thermal magnetized plasmas, it is shown that upper‐hybrid/multiple harmonic electron cyclotron emissions are characterized by a significant magnetic field component, even in the high‐frequency regime. Such a prediction may potentially be tested by upcoming spacecraft missions including the Solar Probe Orbiter and Parker Solar Probe. The present finding may also have a potentially significant ramification for the broader astrophysical contexts.
Excitation of Plasma Irregularities in the F Region of the Ionosphere by Powerful HF Radio Waves of X‐Polarization
Authors: Borisov N. , Honary F. , Li H. 
Published: June 2018

AbstractWe discuss theoretically the excitation of artificial plasma irregularities in the auroral ionosphere by high‐frequency X‐mode radio wave. This is done via a two‐step process. As a first step we adopt the thermal self‐focusing instability excited in the F region of the ionosphere under the action of a strong high‐frequency (HF) radio wave. This instability causes the formation of perturbations of the electron temperature and plasma concentration across the magnetic field. In addition, the plasma becomes depleted in the regions of the electron temperature enhancements and vice versa, since the gradients of plasma concentration and the electron temperature have opposite signs. In such conditions the temperature gradient instability comes into play. As a second step we consider plasma and electron temperature inhomogeneities that appear due to this instability to be responsible for the generation of irregularities with transverse sizes smaller than the typical scales of the self‐focusing instability. Alternative mechanisms such as excitation of the gradient‐drift and the current‐convective instabilities, which are often attributed to the generation of plasma irregularities in the F region and can contribute to the formation of artificial irregularities in the case of X‐mode heating, are also discussed.
Seismic Ground Roll Absorption and Reemission by Sand Dunes
Authors: Arran M. I. , Vriend N. M. , Muyzert E. 
Published: June 2018

AbstractGround roll is a significant source of noise in land seismic data, with crossline scattered ground roll particularly difficult to suppress. This noise arises from surface heterogeneities lateral to the receiver spread, and in desert regions sand dunes are a major contributor. However, the nature of this noise is poorly understood, preventing the design of more effective data acquisition or processing techniques. Here we present numerical simulations demonstrating that a barchan sand dune acts as a resonator, absorbing energy from ground roll and reemitting it over an extensive period of time. We derive and validate a mathematical framework that quantitatively describes the properties of the emitted waves and demonstrate that wave amplitude is estimable from easily measurable bulk properties of the dune. Having identified regions in time, space, and frequency space at which noise will be more significant, we propose reducing dune‐scattered noise through careful survey design and data processing. In particular, we predict that seismic noise will be lower upwind of barchan dunes, and at frequencies far from a resonant frequency 2cS/H, for dune height H and typical seismic velocity within the dune cS. This work is especially relevant to seismic acquisition in the vicinity of a dune field, where scattered noise appears incoherent and difficulties arise with alternative approaches to noise suppression.
Microstructural Control of Physical Properties During Deformation of Porous Limestone
Authors: Brantut Nicolas , Baker Madeline , Hansen Lars N. , Baud Patrick 
Published: June 2018

AbstractWe performed triaxial deformation experiments in Purbeck limestone (13.8% average porosity) across the brittle‐ductile transition and monitored the evolution of permeability and wave velocities as a function of strain. In the brittle regime, the rock yields in dilation. In the ductile regime, the rock first yields in compaction and then undergoes net dilation at some critical level of strain. The permeability increases after failure in the brittle regime and decreases with increasing compaction in the ductile regime. The wave velocities decrease with increasing strain, and the material becomes transversely isotropic. At axial strains of the order of 5%, the anisotropy parameters (from Thomsen, 1986) are around ε ≈ −0.2 and δ ≈ decrease with increasing axial strain beyond the yield point−0.3. Under hydrostatic conditions, the rock also yields in compaction. The hydrostatic yield point is not marked by any significant drop or increase in wave velocity during loading, but wave velocities decrease (and therefore crack density increases) significantly upon unloading. In all our tests, the permeability change is proportional to the initial porosity change until the point of net dilation is reached. The strain at that point also acts as a scaling factor for the relative drop in P and S wave velocities during deformation. All our experimental data point to a disconnection between the evolution of permeability, porosity, and wave velocities during deformation in the ductile regime: permeability is controlled by a fraction of the micropore network, while wave velocities are mostly influenced by microcracks that do not contribute significantly to either the total rock porosity or fluid flow properties.
Structural Control on Downdip Locking Extent of the Himalayan Megathrust
Authors: Lindsey Eric O. , Almeida Rafael , Mallick Rishav , Hubbard Judith , Bradley Kyle , Tsang Louisa L. H. , Liu Yixiang , Burgmann Roland , Hill Emma M. 
Published: June 2018

AbstractGeologic reconstructions of the Main Himalayan Thrust in Nepal show a laterally extensive midcrustal ramp, hypothesized to form the downdip boundary of interseismic locking. Using a recent compilation of interseismic GPS velocities and a simplified model of fault coupling, we estimate the width of coupling across Nepal using a series of two‐dimensional transects. We find that the downdip width of fault coupling increases smoothly from 70 to 90 km in eastern Nepal to 100–110 km in central Nepal, then narrows again in western Nepal. The inferred coupling transition is closely aligned with geologic reconstructions of the base of the midcrustal ramp in central and eastern Nepal, but in western Nepal, the data suggest that the location is intermediate between two proposed ramp locations. The result for western Nepal implies either an anomalous coupling transition that occurs along a shallowly dipping portion of the fault or that both ramps may be partially coupled and that a proposed crustal‐scale duplexing process may be active during the interseismic period. We also find that the models require a convergence rate of 15.5 ± 2 mm/year throughout Nepal, reducing the geodetic moment accumulation rate by up to 30% compared with earlier models, partially resolving an inferred discrepancy between geodetic and paleoseismic estimates of moment release across the Himalaya.
Bias and Sensitivity of Boundary Layer Clouds and Surface Radiative Fluxes in MERRA‐2 and Airborne Observations Over the Beaufort Sea During the ARISE Campaign
Authors: Segal Rozenhaimer Michal , Barton Neil , Redemann Jens , Schmidt Sebastian , LeBlanc Samuel , Anderson Bruce , Winstead Edward , Corr Chelsea A. , Moore Richard , Thornhill K. Lee , Cullather Richard I. 
Published: June 2018

AbstractThe representation of Arctic surface radiative fluxes in atmospheric models and reanalyses is integral to understanding relevant physical processes, yet testing of these models is confounded by a scarcity of in situ observations of near‐surface atmospheric state profiles, cloud vertical structure, cloud phase, and surface properties. Here, airborne measurements obtained from the Arctic Radiation IceBridge Sea&Ice Experiment (ARISE) during fall 2014 are compared with concurrent products from the Modern‐Era Retrospective analysis for Research and Applications, version 2 (MERRA‐2). Both data sets are then used as input to a radiative transfer model to produce surface radiative fluxes over multiple locations in the Beaufort Sea under the various conditions observed during ARISE. The sensitivity of the simulated fluxes is assessed and compared between these two data sets. Then, the relative contribution of atmospheric state, boundary layer clouds, and their properties to the sensitivity of the simulated surface fluxes is assessed. In our comparisons with ARISE observations we found that MERRA‐2 has a warm temperature bias near the surface and it underestimates near‐surface clouds and cloud liquid and ice water content. These prevail over both open water and sea ice surfaces. Our sensitivity analysis showed that boundary layer cloud vertical structure and water content account for more than 70% of the difference between MERRA‐2 and the radiative fluxes calculated from airborne observations and that differences in boundary layer atmospheric state parameters contribute about 10–20% to the positive bias in the longwave surface flux.
Diagnosing Physical Mechanisms Leading to Pure Heat Waves Versus Pure Tropical Nights Over the Korean Peninsula
Authors: Hong Jin‐Sil , Yeh Sang‐Wook , Seo Kyong‐Hwan 
Published: June 2018

AbstractThis study analyzes differences in the mechanisms leading to anomalously high‐temperature weather events, such as heat waves and tropical nights, in Korea. We identify pure heat wave and pure tropical night events during the period from 1979 to 2016. Based on composite analyses for each case, we identify different mechanisms leading to pure heat waves and pure tropical nights. The structures including low‐level atmospheric circulations, specific humidity, wind, and the atmospheric stability are quite different between pure heat waves and pure tropical nights. Pure heat waves occur under barotropic‐like atmospheric conditions, with a stable low layer and dry air due to anomalous easterly winds over the Korean Peninsula. In contrast, pure tropical nights occur under baroclinic‐like atmospheric conditions, with warm, humid air advected by southwesterly winds. These results indicate that above‐normal levels of incoming shortwave radiation combined with adiabatic warming contribute to pure heat waves, whereas pure tropical nights are associated with above‐normal longwave radiation and/or warm advection over the Korean Peninsula. This implies that different physical factors must be considered for accurate, regional‐scale predictions of heat waves and tropical night events.
Selective manipulation of electronically excited states through strong light–matter interactions
Authors: Stranius Kati , Hertzog Manuel , Börjesson Karl 
Published: June 2018

AbstractStrong coupling between light and matter leads to the spontaneous formation of hybrid light–matter states, having different energies than the uncoupled states. This opens up for new ways of modifying the energy landscape of molecules without changing their atoms or structure. Heavy metal-free organic light emitting diodes (OLED) use reversed intersystem crossing (RISC) to harvest light from excited triplet states. This is a slow process, thus increasing the rate of RISC could potentially enhance OLED performance. Here we demonstrate selective coupling of the excited singlet state of Erythrosine B without perturbing the energy level of a nearby triplet state. The coupling reduces the triplet–singlet energy gap, leading to a four-time enhancement of the triplet decay rate, most likely due to an enhanced rate of RISC. Furthermore, we anticipate that strong coupling can be used to create energy-inverted molecular systems having a singlet ground and lowest excited state.
Model-based identification of TNFα-induced IKKβ-mediated and IκBα-mediated regulation of NFκB signal transduction as a tool to quantify the impact of drug-induced liver injury compounds
Authors: Oppelt Angela , Kaschek Daniel , Huppelschoten Suzanna , Sison-Young Rowena , Zhang Fang , Buck-Wiese Marie , Herrmann Franziska , Malkusch Sebastian , Krüger Carmen L. , Meub Mara , Merkt Benjamin , Zimmermann Lea , Schofield Amy , Jones Robert P. , Malik Hassan , Schilling Marcel , Heilemann Mike , van de Water Bob , Goldring Christopher E. , Park B. Kevin , Timmer Jens , Klingmüller Ursula 
Published: June 2018

AbstractDrug-induced liver injury (DILI) has become a major problem for patients and for clinicians, academics and the pharmaceutical industry. To date, existing hepatotoxicity test systems are only poorly predictive and the underlying mechanisms are still unclear. One of the factors known to amplify hepatotoxicity is the tumor necrosis factor alpha (TNFα), especially due to its synergy with commonly used drugs such as diclofenac. However, the exact mechanism of how diclofenac in combination with TNFα induces liver injury remains elusive. Here, we combined time-resolved immunoblotting and live-cell imaging data of HepG2 cells and primary human hepatocytes (PHH) with dynamic pathway modeling using ordinary differential equations (ODEs) to describe the complex structure of TNFα-induced NFκB signal transduction and integrated the perturbations of the pathway caused by diclofenac. The resulting mathematical model was used to systematically identify parameters affected by diclofenac. These analyses showed that more than one regulatory module of TNFα-induced NFκB signal transduction is affected by diclofenac, suggesting that hepatotoxicity is the integrated consequence of multiple changes in hepatocytes and that multiple factors define toxicity thresholds. Applying our mathematical modeling approach to other DILI-causing compounds representing different putative DILI mechanism classes enabled us to quantify their impact on pathway activation, highlighting the potential of the dynamic pathway model as a quantitative tool for the analysis of DILI compounds.