bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating the Origin of Continual Radio Frequency Impulses During Explosive Volcanic Eruptions
Authors: Behnke S. A. , Edens H. E. , Thomas R. J. , Smith C. M. , McNutt S. R. , Van Eaton A. R. , Cimarelli C. , Cigala V. 
Published: March 2018

AbstractVolcanic lightning studies have revealed that there is a relatively long‐lasting source of very high frequency radiation associated with the onset of explosive volcanic eruptions that is distinct from radiation produced by lightning. This very high frequency signal is referred to as “continual radio frequency (CRF)” due to its long‐lasting nature. The discharge mechanism producing this signal was previously hypothesized to be caused by numerous, small (10–100 m) leader‐forming discharges near the vent of the volcano. To test this hypothesis, a multiparametric data set of electrical and volcanic activity occurring during explosive eruptions of Sakurajima Volcano in Japan was collected from May to June 2015. Our observations show that a single CRF impulse has a duration on the order of 160 ns (giving an upper limit on discharge length of 10 m) and is distinct from near‐vent lightning discharges that were on the order of 30 m in length. CRF impulses did not produce discernible electric field changes and occurred in the absence of a net static electric field. Lightning mapping data and infrared video observations of the eruption column showed that CRF impulses originated from the gas thrust region of the column. These observations indicate that CRF impulses are not produced by small, leader‐forming discharges but rather are more similar to a streamer discharge, likely on the order of a few meters in length.
The Optical Properties of Limonene Secondary Organic Aerosols: The Role of NO3, OH, and O3 in the Oxidation Processes
Authors: Peng Chao , Wang Weigang , Li Kun , Li Junling , Zhou Li , Wang Lingshu , Ge Maofa 
Published: March 2018

AbstractLimonene, a typical proxy of monoterpenes emitted from biogenic sources, plays an important role in secondary organic aerosol (SOA) formation. However, the optical properties of SOA generated from limonene under various oxidation pathways remain poorly understood. In this study, we investigate the refractive index (RI) of limonene SOA produced from four oxidation conditions with cavity ring‐down spectrometer (CRDS) and photoacoustic extinctiometer operated at 532 and 375 nm. Our results show that there is a significant difference in RI values of SOA produced from NO3 oxidation compared to other oxidation pathways. The mean values of RI of SOA produced from NO3 oxidation, NOx oxidation, OH oxidation with NOx‐free, and O3 oxidation experiments are 1.578, 1.469, 1.495, and 1.494 at 532 nm; and 1.591, 1.527, 1.513, and 1.537 at 375 nm, respectively, while no detectable absorption is found in all oxidation conditions. We attribute the high RI values of SOA by NO3 oxidation to two factors: a large proportion of organic nitrates and high‐molecular‐weight dimers/oligomers in the SOA. Our study results indicate that the nighttime chemistry may significantly influence the optical properties of limonene oxidation products. The RI values of limonene SOA generated under various oxidation conditions at different wavelengths retrieved in our laboratory experiments could help improve the model predictions for evaluating the effect of biogenic SOA on the global radiative forcing as well as climate change.
Global Scale Analysis of Martian Landslide Mobility and Paleoenvironmental Clues
Authors: Crosta Giovanni Battista , De Blasio Fabio Vittorio , Frattini Paolo 
Published: March 2018

AbstractThe mobility of landslides on Mars is studied based on a database of 3,118 events. To establish the volume of the landslides for the whole data set based on the deposit area, a new volume‐area relationship based on a representative data set of 222 landslides is used. By plotting the H/L ratio between fall height H and runout L versus volume, the landslide mobility is analyzed and compared with existing empirical relationships for Martian and terrestrial landslides. By analyzing the mobility in terms of normalized residuals, that is, the relative deviation of the H/L ratio from the data set best‐fit line, mobility is found to depend on both the landslide location on Mars and the landslide typology. This allows us to identify four different types of high‐mobility (hypermobile) landslides. Three classes of high‐mobility landslides are associated respectively to meteoroid impact, the Olympus Mons aureoles, and landslides with Toreva‐block failure style, and their mobility can be explained by the peculiar flow mechanics. The fourth class includes landslides associated with isolated craters, those in the regions wetted by the putative Oceanus Borealis, and the ones at high latitudes. We suggest that the common factor behind all the hypermobile landslides of this fourth kind is the presence of ice. This is confirmed by our data showing that landslides increase in mobility with latitude. The latitudinal trend mirrors the distribution of ice as detected by radar, neutron probes, and the presence of glacial and layered ejecta morphologies. Because the overall landslide distribution supports the presence of ice‐lubricated conditions, two ice lubrication models are presented showing how ice melting within or underneath the landslides could enhance mobility. By proper analysis in terms of apparent friction residuals, we find that the mobility of landslides in Valles Marineris with the largest landslide concentration is lower than average. We explain this circumstance partly from the smaller role of ice in equatorial Valles Marineris and partly because the collapses from high slope relief imply high‐speed impact with the floor valley confinement, loss of momentum, and decrease in mobility. Environmental consequences imply that the present subsurface ice distribution may have been persistent throughout the Amazonian period.
An Evaluation of Nitrate, fDOM, and Turbidity Sensors in New Hampshire Streams
Authors: Snyder Lisle , Potter Jody D. , McDowell William H. 
Published: March 2018

AbstractA state‐of‐the‐art network of water quality sensors was established in 2012 to gather year‐round high temporal frequency hydrochemical data in streams and rivers throughout the state of New Hampshire. This spatially extensive network includes eight headwater stream and two main stem river monitoring sites, spanning a variety of stream orders and land uses. Here we evaluate the performance of nitrate, fluorescent dissolved organic matter (fDOM), and turbidity sensors included in the sensor network. Nitrate sensors were first evaluated in the laboratory for interference by different forms of dissolved organic carbon (DOC), and then for accuracy in the field across a range of hydrochemical conditions. Turbidity sensors were assessed for their effectiveness as a proxy for concentrations of total suspended solids (TSS) and total particulate C and N, and fDOM as a proxy for concentrations of dissolved organic matter. Overall sensor platform performance was also examined by estimating percentage of data loss due to sensor failures or related malfunctions. Although laboratory sensor trials show that DOC can affect optical nitrate measurements, our validations with grab samples showed that the optical nitrate sensors provide a reliable measurement of NO3 concentrations across a wide range of conditions. Results showed that fDOM is a good proxy for DOC concentration (r2 = 0.82) but is a less effective proxy for dissolved organic nitrogen (r2 = 0.41). Turbidity measurements from sensors correlated well with TSS (r2 = 0.78), PC (r2 = 0.53), and PN (r2 = 0.51).
Sociohydrological Impacts of Water Conservation Under Anthropogenic Drought in Austin, TX (USA)
Authors: Breyer Betsy , Zipper Samuel C. , Qiu Jiangxiao 
Published: March 2018

AbstractMunicipal water providers increasingly respond to drought by implementing outdoor water use restrictions to reduce urban water withdrawals and maintain water availability. However, restricting urban outdoor water use to support watershed‐scale drought resilience may generate unanticipated cross‐scale interactions, for example, by altering drought response and recovery in urban vegetation or urban streamflow. Despite this, urban water conservation is rarely conceptualized or modeled as endogenous to the water cycle. Here we investigate cross‐scale interactions among urban water conservation and water availability, water use, and sociohydrological response in Austin, TX (USA) during a recent anthropogenic (human‐influenced) drought. Multiscalar statistical analyses demonstrated that outdoor water conservation for reservoir management at the municipal scale produced responses that can cascade both “upward” from the city to the watershed (e.g., decoupling streamflow patterns upstream and downstream of Austin at the watershed scale) and “downward” to exert heterogeneous effects within the city (e.g., redistributing water along a socioeconomic gradient at submunicipal scales, with effects on terrestrial and aquatic ecosystems). We suggest that adapting to anthropogenic drought through irrigation curtailment requires sustained engagement between hydrology and social sciences to integrate socioeconomic status and political feedbacks within and among irrigator groups into the water cycle. Findings from this cross‐disciplinary study highlight the importance of a multiscalar and spatially explicit perspectives in urban sociohydrology research to uncover how water conservation as adaptation to anthropogenic drought links hydrological processes with issues of socioeconomic inequality and spatiotemporal scale in the Anthropocene.
Predictability and Quantification of Complex Groundwater Table Dynamics Driven by Irregular Surface Water Fluctuations
Authors: Xin Pei , Wang Shen S. J. , Shen Chengji , Zhang Zeyu , Lu Chunhui , Li Ling 
Published: March 2018

AbstractShallow groundwater interacts strongly with surface water across a quarter of global land area, affecting significantly the terrestrial eco‐hydrology and biogeochemistry. We examined groundwater behavior subjected to unimodal impulse and irregular surface water fluctuations, combining physical experiments, numerical simulations, and functional data analysis. Both the experiments and numerical simulations demonstrated a damped and delayed response of groundwater table to surface water fluctuations. To quantify this hysteretic shallow groundwater behavior, we developed a regression model with the Gamma distribution functions adopted to account for the dependence of groundwater behavior on antecedent surface water conditions. The regression model fits and predicts well the groundwater table oscillations resulting from propagation of irregular surface water fluctuations in both laboratory and large‐scale aquifers. The coefficients of the Gamma distribution function vary spatially, reflecting the hysteresis effect associated with increased amplitude damping and delay as the fluctuation propagates. The regression model, in a relatively simple functional form, has demonstrated its capacity of reproducing high‐order nonlinear effects that underpin the surface water and groundwater interactions. The finding has important implications for understanding and predicting shallow groundwater behavior and associated biogeochemical processes, and will contribute broadly to studies of groundwater‐dependent ecology and biogeochemistry.
New Observations Disagree With Previous Interpretations of Surface Rupture Along the Himalayan Frontal Thrust During the Great 1934 Bihar‐Nepal Earthquake
Authors: Wesnousky Steven G. , Kumahara Yasuhiro , Nakata Takashi , Chamlagain Deepak , Neupane Prajwal 
Published: March 2018

AbstractReinvestigation reveals observations that do not support prior claims that the great Mw 8.4 Bihar‐Nepal earthquake produced surface rupture along the Himalayan Frontal Thrust of Nepal. While it may be viewed as reasonable to suggest that the Main Himalayan Frontal Thrust was the source of the 1934 Bihar‐Nepal earthquake on geophysical grounds, decisive and substantiating geological evidence that it produced surface rupture along the trace of the Himalayan Frontal Thrust remains lacking.
Analysis of Intense Z‐Mode Emission Observed During the Cassini Proximal Orbits
Authors: Menietti J. D. , Averkamp T. F. , Ye S.‐Y. , Sulaiman A. H. , Morooka M. W. , Persoon A. M. , Hospodarsky G. B. , Kurth W. S. , Gurnett D. A. , Wahlund J.‐E. 
Published: March 2018

AbstractThe role of Z‐mode emission in the diffusive scattering and resonant acceleration of electrons is believed to be important at Saturn. A survey of the “5 kHz” component of this emission at Saturn earlier reported strong intensity in the lower density regions where the ratio of plasma frequency to cyclotron frequency, fp/fc < 1. At Saturn this occurs along the inner edge of the Enceladus torus near the equator and at higher latitudes. Using the Cassini Radio and Plasma Wave Science instrument observations during the Cassini proximal orbits, we have now identified these emissions extending down to and within the ionosphere. Wave polarization measurements and unique frequency cutoffs are used to positively identify the wave mode. Analogous to the role of whistler mode chorus at Earth, Saturn Z‐mode emissions may interact with electrons contributing to the filling or depleting of Saturn's inner radiation belts.
Defining Flood Zone Transitions in Low‐Gradient Coastal Regions
Authors: Bilskie M. V. , Hagen S. C. 
Published: March 2018

AbstractWorldwide, coastal, and deltaic communities are susceptible to flooding from the individual and combined effects of rainfall excess and astronomic tide and storm surge inundation. Such flood events are a present (and future) cause of concern as observed from recent storms such as the 2016 Louisiana flood and Hurricanes Harvey, Irma, and Maria. To assess flood risk across coastal landscapes, it is advantageous to first delineate flood transition zones, which we define as areas susceptible to hydrologic and coastal flooding and their collective interaction. We utilize numerical simulations combining rainfall excess and storm surge for the 2016 Louisiana flood to describe a flood transition zone for southeastern Louisiana. We show that the interaction of rainfall excess with coastal surge is nonlinear and less than the superposition of their individual components. Our analysis provides a foundation to define flooding zones across coastal landscapes throughout the world to support flood risk assessments.
Autocorrelation Study of Solar Wind Plasma and IMF Properties as Measured by the MAVEN Spacecraft
Authors: Marquette Melissa L. , Lillis Robert J. , Halekas J. S. , Luhmann J. G. , Gruesbeck J. R. , Espley J. R. 
Published: March 2018

AbstractIt has long been a goal of the heliophysics community to understand solar wind variability at heliocentric distances other than 1 AU, especially at ∼1.5 AU due to not only the steepening of solar wind stream interactions outside 1 AU but also the number of missions available there to measure it. In this study, we use 35 months of solar wind and interplanetary magnetic field (IMF) data taken at Mars by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft to conduct an autocorrelation analysis of the solar wind speed, density, and dynamic pressure, which is derived from the speed and density, as well as the IMF strength and orientation. We found that the solar wind speed is coherent, that is, has an autocorrelation coefficient above 1/e, over roughly 56 hr, while the density and pressure are coherent over smaller intervals of roughly 25 and 20 hr, respectively, and that the IMF strength is coherent over time intervals of approximately 20 hr, while the cone and clock angles are considerably less steady but still somewhat coherent up to time lags of roughly 16 hr. We also found that when the speed, density, pressure, or IMF strength is higher than average, the solar wind or IMF becomes uncorrelated more quickly, while when they are below average, it tends to be steadier. This analysis allows us to make estimates of the values of solar wind plasma and IMF parameters when they are not directly measured and provide an approximation of the error associated with that estimate.
Scattering Matrix for Typical Urban Anthropogenic Origin Cement Dust and Discrimination of Representative Atmospheric Particulates
Authors: Liu Jia , Zhang Yongming , Zhang Qixing , Wang Jinjun 
Published: March 2018

AbstractThe complete scattering matrix for cement dust was measured as a function of scattering angle from 5° to 160° at a wavelength of 532 nm, as a representative of mineral dust of anthropogenic origin in urban areas. Other related characteristics of cement dust, such as particle size distribution, chemical composition, refractive index, and micromorphology, were also analyzed. For this objective, a newly improved apparatus was built and calibrated using water droplets. Measurements of water droplets were in good agreement with Lorenz‐Mie calculations. To facilitate the direct applicability of measurements for cement dust in radiative transfer calculation, the synthetic scattering matrix was computed and defined over the full scattering angle range from 0° to 180°. The scattering matrices for cement dust and typical natural mineral dusts were found to be similar in trends and angular behaviors. Angular distributions of all matrix elements were confined to rather limited domains. To promote the application of light‐scattering matrix in atmospheric observation and remote sensing, discrimination methods for various atmospheric particulates (cement dust, soot, smolder smoke, and water droplets) based on the angular distributions of their scattering matrix elements are discussed. The ratio −F12/F11 proved to be the most effective discrimination method when a single matrix element is employed; aerosol identification can be achieved based on −F12/F11 values at 90° and 160°. Meanwhile, the combinations of −F12/F11 with F22/F11 (or (F11 − F22)/(F11 + F22)) or −F12/F11 with F44/F11 at 160° can be used when multiple matrix elements at the same scattering angle are selected.
Low‐cost Kinect Version 2 imaging system for breath hold monitoring and gating: Proof of concept study for breast cancer VMAT radiotherapy
Authors: Edmunds David M. , Gothard Lone , Khabra Komel , Kirby Anna , Madhale Poonam , McNair Helen , Roberts David , Tang KK , Symonds‐Tayler Richard , Tahavori Fatemeh , Wells Kevin , Donovan Ellen 
Published: March 2018

AbstractVoluntary inspiration breath hold (VIBH) for left breast cancer patients has been shown to be a safe and effective method of reducing radiation dose to the heart. Currently, VIBH protocol compliance is monitored visually. In this work, we establish whether it is possible to gate the delivery of radiation from an Elekta linac using the Microsoft Kinect version 2 (Kinect v2) depth sensor to measure a patient breathing signal. This would allow contactless monitoring during VMAT treatment, as an alternative to equipment–assisted methods such as active breathing control (ABC). Breathing traces were acquired from six left breast radiotherapy patients during VIBH. We developed a gating interface to an Elekta linac, using the depth signal from a Kinect v2 to control radiation delivery to a programmable motion platform following patient breathing patterns. Radiation dose to a moving phantom with gating was verified using point dose measurements and a Delta4 verification phantom. 60 breathing traces were obtained with an acquisition success rate of 100%. Point dose measurements for gated deliveries to a moving phantom agreed to within 0.5% of ungated delivery to a static phantom using both a conventional and VMAT treatment plan. Dose measurements with the verification phantom showed that there was a median dose difference of better than 0.5% and a mean (3% 3 mm) gamma index of 92.6% for gated deliveries when using static phantom data as a reference. It is possible to use a Kinect v2 device to monitor voluntary breath hold protocol compliance in a cohort of left breast radiotherapy patients. Furthermore, it is possible to use the signal from a Kinect v2 to gate an Elekta linac to deliver radiation only during the peak inhale VIBH phase.
Toward Immunocompetent 3D Skin Models
Authors: Pupovac Aleta , Senturk Berna , Griffoni Chiara , Maniura‐Weber Katharina , Rottmar Markus , McArthur Sally L. 
Published: March 2018

Abstract3D human skin models provide a platform for toxicity testing, biomaterials evaluation, and investigation of fundamental biological processes. However, the majority of current in vitro models lack an inflammatory system, vasculature, and other characteristics of native skin, indicating scope for more physiologically complex models. Looking at the immune system, there are a variety of cells that could be integrated to create novel skin models, but to do this effectively it is also necessary to understand the interface between skin biology and tissue engineering as well as the different roles the immune system plays in specific health and disease states. Here, a progress report on skin immunity and current immunocompetent skin models with a focus on construction methods is presented; scaffold and cell choice as well as the requirements of physiologically relevant models are elaborated. The wide range of technological and fundamental challenges that need to be addressed to successfully generate immunocompetent skin models and the steps currently being made globally by researchers as they develop new models are explored. Induced pluripotent stem cells, microfluidic platforms to control the model environment, and new real‐time monitoring techniques capable of probing biochemical processes within the models are discussed.
Current Concepts in Meniscus Tissue Engineering and Repair
Authors: Bilgen Bahar , Jayasuriya Chathuraka T. , Owens Brett D. 
Published: March 2018

AbstractThe meniscus is the most commonly injured structure in the human knee. Meniscus deficiency has been shown to lead to advanced osteoarthritis (OA) due to abnormal mechanical forces, and replacement strategies for this structure have lagged behind other tissue engineering endeavors. The challenges include the complex 3D structure with individualized size parameters, the significant compressive, tensile and shear loads encountered, and the poor blood supply. In this progress report, a review of the current clinical treatments for different types of meniscal injury is provided. The state‐of‐the‐art research in cellular therapies and novel cell sources for these therapies is discussed. The clinically available cell‐free biomaterial implants and the current progress on cell‐free biomaterial implants are reviewed. Cell‐based tissue engineering strategies for the repair and replacement of meniscus are presented, and the current challenges are identified. Tissue‐engineered meniscal biocomposite implants may provide an alternative solution for the treatment of meniscal injury to prevent OA in the long run, because of the limitations of the existing therapies.