bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antitumor activity of Chlorella sorokiniana and Scenedesmus sp. microalgae native of Nuevo León State, México
Authors: Reyna-Martinez Raul , Gomez-Flores Ricardo , López-Chuken Ulrico , Quintanilla-Licea Ramiro , Caballero-Hernandez Diana , Rodríguez-Padilla Cristina , Beltrán-Rocha Julio Cesar , Tamez-Guerra Patricia 
Published: February 2018

Cancer cases result in 13% of all deaths worldwide. Unwanted side effects in patients under conventional treatments have led to the search for beneficial alternative therapies. Microalgae synthesize compounds with known in vitro and in vivo biological activity against different tumor cell lines. Therefore, native microalgae from the State of Nuevo Leon, Mexico may become a potential source of antitumor agents. The aim of the present study was to evaluate the in vitro cytotoxic effect of Nuevo Leon regional Chlorella sorokiniana (Chlorellales: Chlorellaceae) and Scenedesmus sp. (Chlorococcales: Scenedesmaceae). Native microalgae crude organic extracts cytotoxicity against murine L5178Y-R lymphoma cell line and normal lymphocyte proliferation were evaluated using the MTT reduction colorimetric assay. Cell death pathway was analyzed by acridine orange and ethidium bromide staining, DNA degradation in 2% agarose gel electrophoresis and caspases activity. Results indicated significant (p < 0.05) 61.89% ± 3.26% and 74.77% ± 1.84% tumor cytotoxicity by C. sorokiniana and Scenedesmus sp. methanol extracts, respectively, at 500 µg/mL, by the mechanism of apoptosis. This study contributes to Mexican microalgae biodiversity knowledge and their potential as antitumor agent sources.
The Temperature Sensitivity (Q10) of Soil Respiration: Controlling Factors and Spatial Prediction at Regional Scale Based on Environmental Soil Classes
Authors: Meyer N. , Welp G. , Amelung W. 
Published: February 2018

AbstractThe temperature sensitivity of heterotrophic soil respiration is crucial for modeling carbon dynamics but it is variable. Presently, however, most models employ a fixed value of 1.5 or 2.0 for the increase of soil respiration per 10°C increase in temperature (Q10). Here we identified the variability of Q10 at a regional scale (Rur catchment, Germany/Belgium/Netherlands). We divided the study catchment into environmental soil classes (ESCs), which we define as unique combinations of land use, aggregated soil groups, and texture. We took nine soil samples from each ESC (108 samples) and incubated them at four soil moisture levels and five temperatures (5–25°C). We hypothesized that Q10 variability is controlled by soil organic carbon (SOC) degradability and soil moisture and that ESC can be used as a widely available proxy for Q10, owing to differences in SOC degradability. Measured Q10 values ranged from 1.2 to 2.8 and were correlated with indicators of SOC degradability (e.g., pH, r = −0.52). The effect of soil moisture on Q10 was variable: Q10 increased with moisture in croplands but decreased in forests. The ESC captured significant parts of Q10 variability under dry (R2 = 0.44) and intermediate (R2 = 0.36) moisture conditions, where Q10 increased in the order cropland<grassland<forest. Overall, the estimated heterotrophic CO2 release from the catchment was up to 45% lower when ESC‐ and moisture‐specific Q10 values were used instead of 1.5, suggesting that scaling Q10 on the basis of both ESC and moisture might be a promising concept for spatially continuous assessments of carbon turnover at regional scales.
Paleoaltimetry Potentiality of Branched GDGTs From Southern Tibet
Authors: Bai Yan , Chen Chihao , Xu Qiang , Fang Xiaomin 
Published: February 2018

AbstractPaleoaltimetric reconstructions of the southern Tibetan Plateau (TP) are crucial to understand the processes and mechanisms concomitant with the tectonic collision of the Indian and Eurasian continental plates. We measured the branched glycerol dialkyl glycerol tetraether (brGDGT) indices from 88 surface soils from the southern TP and found that alkaline soils exhibited lower MBT′ and MBT′/CBT‐derived MAT (mean annual temperature), while MBT′/CBT‐derived MAT exhibited a strong correlation with altitude (R2 = 0.84; n = 63) for all of the localities with neutral and acidic soils. Differently, we found that MBT′5ME‐derived MAT exhibited a strong relation with altitude even though a mixture of alkaline samples (R2 = 0.72; n = 83). As a result, two regional calibrations were developed, including a neutral and acidic soil calibration based on MBT′/CBT‐MAT and a calibration suitable for both acidic and alkaline soils based on MBT′5ME‐MAT for the southern TP. Based on this new soil calibration data set, and a recent global soil calibration data set founded on MBT′5ME, we calculated paleo‐MAT of ∼9.49 ± 1.15 to 10.38 ± 1.47°C at ∼15 Ma, respectively, for the Namling Basin. Applying these soil calibrations, the paleoaltitudes of the Namling Basin can be calculated to have been between 4.36 ± 0.41 km above sea level (asl) and 4.43 ± 0.36 km asl at ∼15 Ma, respectively, similar to the paleoaltitudes of ∼4.7–5.4 km asl at ∼15 Ma inferred from the floral physiognomy of Namling Basin fossils and stable isotopes. These findings would suggest the applicability of MBT′/CBT (and/or MBT′5ME) indices as paleotopographic and paleotemperature proxies on the southern TP.
30 Years in the Life of an Active Submarine Volcano: A Time‐Lapse Bathymetry Study of the Kick‐'em‐Jenny Volcano, Lesser Antilles
Authors: Allen R. W. , Berry C. , Henstock T. J. , Collier J. S. , Dondin F. J‐Y. , Rietbrock A. , Latchman J. L. , Robertson R. E. A. 
Published: February 2018

AbstractEffective monitoring is an essential part of identifying and mitigating volcanic hazards. In the submarine environment this is more difficult than onshore because observations are typically limited to land‐based seismic networks and infrequent shipboard surveys. Since the first recorded eruption in 1939, the Kick‐'em‐Jenny (KeJ) volcano, located 8 km off northern Grenada, has been the source of 13 episodes of T‐phase signals. These distinctive seismic signals, often coincident with heightened body‐wave seismicity, are interpreted as extrusive eruptions. They have occurred with a recurrence interval of around a decade, yet direct confirmation of volcanism has been rare. By conducting new bathymetric surveys in 2016 and 2017 and reprocessing 4 legacy data sets spanning 30 years we present a clearer picture of the development of KeJ through time. Processed grids with a cell size of 5 m and vertical precision on the order of 1–4 m allow us to correlate T‐phase episodes with morphological changes at the volcano's edifice. In the time‐period of observation 7.09 × 106m3of material has been added through constructive volcanism – yet 5 times this amount has been lost through landslides. Limited recent magma production suggests that KeJ may be susceptible to larger eruptions with longer repeat times than have occurred during the study interval, behavior more similar to sub‐aerial volcanism in the arc than previously thought. T‐phase signals at KeJ have a varied origin and are unlikely to be solely the result of extrusive submarine eruptions. Our results confirm the value of repeat swath bathymetry surveys in assessing submarine volcanic hazards.
Storm Time Evolution of Outer Radiation Belt Relativistic Electrons by a Nearly Continuous Distribution of Chorus
Authors: Yang Chang , Xiao Fuliang , He Yihua , Liu Si , Zhou Qinghua , Guo Mingyue , Zhao Wanli 
Published: February 2018

AbstractDuring the 13–14 November 2012 storm, Van Allen Probe A simultaneously observed a 10 h period of enhanced chorus (including quasi‐parallel and oblique propagation components) and relativistic electron fluxes over a broad range of L = 3–6 and magnetic local time = 2–10 within a complete orbit cycle. By adopting a Gaussian fit to the observed wave spectra, we obtain the wave parameters and calculate the bounce‐averaged diffusion coefficients. We solve the Fokker‐Planck diffusion equation to simulate flux evolutions of relativistic (1.8–4.2 MeV) electrons during two intervals when Probe A passed the location L = 4.3 along its orbit. The simulating results show that chorus with combined quasi‐parallel and oblique components can produce a more pronounced flux enhancement in the pitch angle range ∼45°–80°, consistent well with the observation. The current results provide the first evidence on how relativistic electron fluxes vary under the drive of almost continuously distributed chorus with both quasi‐parallel and oblique components within a complete orbit of Van Allen Probe.
A Model of Aftershock Migration Driven by Afterslip
Authors: Perfettini H. , Frank W. B. , Marsan D. , Bouchon M. 
Published: February 2018

AbstractAftershocks region have been extensively reported to expand logarithmically with time. The associated migration velocity is typically of the order of several km/decade but can be much larger, especially when observing early aftershock sequences, seismic swarms, or tremors. We present here a model for the expansion of aftershock zones based on the idea that aftershocks are triggered as afterslip grows with time along the fault. One of the model assumptions is that aftershocks are triggered when a critical level of afterslip is reached. We predict that the migration velocity Vp at time t following the mainshock is given by
, where
is a frictional parameter, Δτ a characteristic value for the stress perturbation, c the radius of the stress perturbation, and ζ a constant of order unity. The scaling
implies a logarithmic expansion of the aftershock zone with time. The migration velocities predicted by our model are in quantitative agreement with the observations reported following aftershock sequence of small and large earthquakes in various tectonic settings, seismic swarms, and tremor sequences.
Multidecadal Variability in Surface Albedo Feedback Across CMIP5 Models
Authors: Schneider Adam , Flanner Mark , Perket Justin 
Published: February 2018

AbstractPrevious studies quantify surface albedo feedback (SAF) in climate change, but few assess its variability on decadal time scales. Using the Coupled Model Intercomparison Project Version 5 (CMIP5) multimodel ensemble data set, we calculate time evolving SAF in multiple decades from surface albedo and temperature linear regressions. Results are meaningful when temperature change exceeds 0.5 K. Decadal‐scale SAF is strongly correlated with century‐scale SAF during the 21st century. Throughout the 21st century, multimodel ensemble mean SAF increases from 0.37 to 0.42 W m−2 K−1. These results suggest that models' mean decadal‐scale SAFs are good estimates of their century‐scale SAFs if there is at least 0.5 K temperature change. Persistent SAF into the late 21st century indicates ongoing capacity for Arctic albedo decline despite there being less sea ice. If the CMIP5 multimodel ensemble results are representative of the Earth, we cannot expect decreasing Arctic sea ice extent to suppress SAF in the 21st century.
A Multipixel Time Series Analysis Method Accounting for Ground Motion, Atmospheric Noise, and Orbital Errors
Authors: Jolivet R. , Simons M. 
Published: February 2018

AbstractInterferometric synthetic aperture radar time series methods aim to reconstruct time‐dependent ground displacements over large areas from sets of interferograms in order to detect transient, periodic, or small‐amplitude deformation. Because of computational limitations, most existing methods consider each pixel independently, ignoring important spatial covariances between observations. We describe a framework to reconstruct time series of ground deformation while considering all pixels simultaneously, allowing us to account for spatial covariances, imprecise orbits, and residual atmospheric perturbations. We describe spatial covariances by an exponential decay function dependent of pixel‐to‐pixel distance. We approximate the impact of imprecise orbit information and residual long‐wavelength atmosphere as a low‐order polynomial function. Tests on synthetic data illustrate the importance of incorporating full covariances between pixels in order to avoid biased parameter reconstruction. An example of application to the northern Chilean subduction zone highlights the potential of this method.
Evidence for the Maintenance of Slowly Varying Equatorial Currents by Intraseasonal Variability
Authors: Greatbatch Richard J. , Claus Martin , Brandt Peter , Matthießen Jan‐Dirk , Tuchen Franz Philip , Ascani François , Dengler Marcus , Toole John , Roth Christina , Farrar J. Thomas 
Published: February 2018

AbstractRecent evidence from mooring data in the equatorial Atlantic reveals that semiannual and longer time scale ocean current variability is close to being resonant with equatorial basin modes. Here we show that intraseasonal variability, with time scales of tens of days, provides the energy to maintain these resonant basin modes against dissipation. The mechanism is analogous to that by which storm systems in the atmosphere act to maintain the atmospheric jet stream. We demonstrate the mechanism using an idealized model setup that exhibits equatorial deep jets. The results are supported by direct analysis of available mooring data from the equatorial Atlantic Ocean covering a depth range of several thousand meters. The analysis of the mooring data suggests that the same mechanism also helps maintain the seasonal variability.
Decadal Monsoon‐ENSO Relationships Reexamined
Authors: Yun Kyung‐Sook , Timmermann Axel 
Published: February 2018

AbstractThe strength of the El Niño‐Southern Oscillation (ENSO)‐Indian summer monsoon rainfall (ISMR) relationship shows considerable decadal fluctuations, which have been previously linked to low‐frequency climatic processes such as shifts in ENSO's center of action or the Atlantic Multidecadal Oscillation. However, random variability can also cause similar variations in the relationship between climate phenomena. Here we propose a statistical test to determine whether the observed time‐evolving correlations between ENSO and ISMR are different from those expected from a simple stochastic null hypothesis model. The analysis focuses on the time evolution of moving correlations, their expected variance, and probabilities for rapid transitions. The results indicate that the time evolution of the observed running correlation between these climate modes is indistinguishable from a system in which the ISMR signal can be expressed as a stochastically perturbed ENSO signal. This challenges previous deterministic interpretations. Our results are further corroborated by the analysis of climate model simulations.
Radiation Measured for Chinese Satellite SJ‐10 Space Mission
Authors: Zhou Dazhuang , Sun Yeqing , Zhang Binquan , Zhang Shenyi , Sun Yueqiang , Liang Jinbao , Zhu Guangwu , Jing Tao , Yuan Bin , Zhang Huanxin , Zhang Meng , Wang Wei , Zhao Lei 
Published: February 2018

AbstractsSpace biological effects are mainly a result of space radiation particles with high linear energy transfer (LET); therefore, accurate measurement of high LET space radiation is vital. The radiation in low Earth orbits is composed mainly of high‐energy galactic cosmic rays (GCRs), solar energetic particles, particles of radiation belts, the South Atlantic Anomaly, and the albedo neutrons and protons scattered from the Earth's atmosphere. CR‐39 plastic nuclear track detectors sensitive to high LET are the best passive detectors to measure space radiation. The LET method that employs CR‐39 can measure all the radiation LET spectra and quantities. CR‐39 detectors can also record the incident directions and coordinates of GCR heavy ions that pass through both CR‐39 and biosamples, and the impact parameter, the distance between the particle's incident point and the seed's spore, can then be determined. The radiation characteristics and impact parameter of GCR heavy ions are especially beneficial for in‐depth research regarding space radiation biological effects. The payload returnable satellite SJ‐10 provided an excellent opportunity to investigate space radiation biological effects with CR‐39 detectors. The space bio‐effects experiment was successfully conducted on board the SJ‐10 satellite. This paper introduces space radiation in low Earth orbits and the LET method in radiation‐related research and presents the results of nuclear tracks and biosamples hitting distributions of GCR heavy ions, the radiation LET spectra, and the quantities measured for the SJ‐10 space mission. The SJ‐10 bio‐experiment indicated that radiation may produce significant bio‐effects.
Seismicity Controlled by a Frictional Afterslip During a Small‐Magnitude Seismic Sequence (ML < 5) on the Chihshang Fault, Taiwan
Authors: Canitano Alexandre , Godano Maxime , Hsu Ya‐Ju , Lee Hsin‐Ming , Linde Alan T. , Sacks Selwyn 
Published: February 2018

AbstractWe report evidence for frictional afterslip at shallow depths (about 5 to 7 km) during a small‐magnitude seismic sequence (withML<5) along the Chihshang Fault, a main active structure of the Longitudinal Valley, in southeast Taiwan. The afterslip, which was recorded by a nearby borehole dilatometer, lasted about a month with a cumulative geodetic moment magnitude of 4.8 ± 0.2. The afterslip comprised two stages and controlled the aftershock sequence. The first postseismic stage, which followed aML4.6 earthquake, lasted about 6 h and mostly controlled the ruptures of neighboring asperities (e.g., multiplets) near the hypocenter. Then, a 4 week duration large afterslip event following aML4.9 earthquake controlled the rate of aftershocks during its first 2 days through brittle creep. The study presents a rare case of simultaneous seismological and geodetic observations for afterslip following earthquakes with magnitude lower than 5. Furthermore, the geodetic moment of the postseismic phase is at least equivalent to the coseismic moment of the sequence.
The Role of Oceanic Transform Faults in Seafloor Spreading: A Global Perspective From Seismic Anisotropy
Authors: Eakin Caroline M. , Rychert Catherine A. , Harmon Nicholas 
Published: February 2018

AbstractMantle anisotropy beneath mid‐ocean ridges and oceanic transforms is key to our understanding of seafloor spreading and underlying dynamics of divergent plate boundaries. Observations are sparse, however, given the remoteness of the oceans and the difficulties of seismic instrumentation. To overcome this, we utilize the global distribution of seismicity along transform faults to measure shear wave splitting of over 550 direct S phases recorded at 56 carefully selected seismic stations worldwide. Applying this source‐side splitting technique allows for characterization of the upper mantle seismic anisotropy, and therefore the pattern of mantle flow, directly beneath seismically active transform faults. The majority of the results (60%) return nulls (no splitting), while the non‐null measurements display clear azimuthal dependency. This is best simply explained by anisotropy with a near vertical symmetry axis, consistent with mantle upwelling beneath oceanic transforms as suggested by numerical models. It appears therefore that the long‐term stability of seafloor spreading may be associated with widespread mantle upwelling beneath the transforms creating warm and weak faults that localize strain to the plate boundary.
New Results on Ionospheric Irregularity Drift Velocity Estimation Using Multi‐GNSS Spaced‐Receiver Array During High‐Latitude Phase Scintillation
Authors: Wang Jun , Morton Y. Jade , Hampton Donald 
Published: February 2018

AbstractThe spaced‐receiver technique using Global Navigation Satellite Systems (GNSS) receivers offers an inexpensive approach for estimating ionospheric irregularity velocity during ionospheric scintillations. Our previous work has demonstrated that correlative studies of the GNSS carrier phase variations can be used to derive irregularity drift velocity at high latitudes. This study expanded upon our previous projects by incorporating Global Navigation Satellite System (GLONASS) signals, investigation on ionospheric irregularity height assumption, and all‐sky imager measurements into the methodology. A case study is presented based on Global Positioning System, Galileo, and GLONASS measurements during a geomagnetic storm event on 20 December 2015, obtained from a closely spaced receiver array at Poker Flat Research Range near Fairbanks, Alaska. The GNSS‐estimated irregularity drift velocities are in general agreement with the measurements from the Poker Flat Incoherent Scatter Radar and the Poker Flat all‐sky imager. The study also shows that the irregularity altitude assumption will not lead to significant variations in the irregularity drift velocity estimates, especially for satellites with relatively high elevations. The techniques presented in this paper demonstrate that GNSS receiver arrays can be used as powerful means to monitor the ionospheric plasma dynamics during space weather events.
Estimating the Natural Flow Regime of Rivers With Long‐Standing Development: The Northern Branch of the Rio Grande
Authors: Blythe Todd L. , Schmidt John C. 
Published: February 2018

AbstractAn estimate of a river's natural flow regime is useful for water resource planning and ecosystem rehabilitation by providing insight into the predisturbance form and function of a river. The natural flow regime of most rivers has been perturbed by development during the 20th century and in some cases, before stream gaging began. The temporal resolution of natural flows estimated using traditional methods is typically not sufficient to evaluate cues that drive native ecosystem function. Additionally, these traditional methods are watershed specific and require large amounts of data to produce accurate results. We present a mass balance method that estimates natural flows at daily time step resolution for the northern branch of the Rio Grande, upstream from the Rio Conchos, that relies only on easily obtained streamflow data. Using an analytical change point method, we identified periods of the measured flow regime during the 20th century for comparison with the estimated natural flows. Our results highlight the significant deviation from natural conditions that occurred during the 20th century. The total annual flow of the northern branch is 95% lower than it would be in the absence of human use. The current 2 year flood has decreased by more than 60%, is shorter in duration, and peaks later in the year. When compared to unregulated flows estimated using traditional mass balance accounting methods, our approach provides similar results.