bluuebunny/crossref_metadata_2025_split huggingface dataset:
A self‐similar scaling for cross‐shelf exchange driven by transient rip currents
Authors: Suanda Sutara H. , Feddersen Falk 
Published: June 2015

AbstractTransient rip currents, episodic offshore flows from the surf zone to the inner shelf, present a recreational beach hazard and exchange material across the nearshore ocean. The magnitude and offshore extent of transient rip‐current‐induced exchange and its relative importance to other inner shelf exchange processes are poorly understood. Here 120 model simulations with random, normally incident, directionally spread waves spanning a range of beach slopes and wave conditions show that the transient rip current exchange velocity is self‐similar. The nondimensional exchange velocity, surf zone flushing time, and cross‐shore decay length scale are scaled by beach slope and wave properties, depending strongly on wave directional spread. Transient rip‐current‐driven exchange can be compared to other cross‐shelf exchange processes. For example, transient rip‐current‐driven exchange is stronger than wave‐induced Stokes‐drift‐driven exchange up to six surf zone widths from shore.
Abrupt changes in Indian summer monsoon strength during 33,800 to 5500 years B.P.
Authors: Dutt Som , Gupta Anil K. , Clemens Steven C. , Cheng Hai , Singh Raj K. , Kathayat Gayatri , Edwards R. Lawrence 
Published: June 2015

AbstractSpeleothem proxy records from northeastern (NE) India reflect seasonal changes in Indian summer monsoon strength as well as moisture source and transport paths. We have analyzed a new speleothem record from Mawmluh Cave, Meghalaya, India, in order to better understand these processes. The data show a strong wet phase 33,500–32,500 years B.P. followed by a weak/dry phase from 26,000 to 23,500 years B.P. and a very weak phase from 17,000 to 15,000 years B.P. The record suggests abrupt increase in strength during the Bølling‐Allerød and early Holocene periods and pronounced weakening during the Heinrich and Younger Dryas cold events. We infer that these changes in monsoon strength are driven by changes in temperature gradients which drive changes in winds and moisture transport into northeast India.
Fractal patterns in riverbed morphology produce fractal scaling of water storage times
Authors: Aubeneau A. F. , Martin R. L. , Bolster D. , Schumer R. , Jerolmack D. , Packman A. 
Published: June 2015

AbstractRiver topography is famously fractal, and the fractality of the sediment bed surface can produce scaling in solute residence time distributions. Empirical evidence showing the relationship between fractal bed topography and scaling of hyporheic travel times is still lacking. We performed experiments to make high‐resolution observations of streambed topography and solute transport over naturally formed sand bedforms in a large laboratory flume. We analyzed the results using both numerical and theoretical models. We found that fractal properties of the bed topography do indeed affect solute residence time distributions. Overall, our experimental, numerical, and theoretical results provide evidence for a coupling between the sand‐bed topography and the anomalous transport scaling in rivers. Larger bedforms induced greater hyporheic exchange and faster pore water turnover relative to smaller bedforms, suggesting that the structure of legacy morphology may be more important to solute and contaminant transport in streams and rivers than previously recognized.
A subsurface structure change associated with the eruptive activity at Sakurajima Volcano, Japan, inferred from an accurately controlled source
Authors: Maeda Yuta , Yamaoka Koshun , Miyamachi Hiroki , Watanabe Toshiki , Kunitomo Takahiro , Ikuta Ryoya , Yakiwara Hiroshi , Iguchi Masato 
Published: June 2015

AbstractTemporal variations of Green functions associated with the eruptive activity at Sakurajima Volcano, Japan, were estimated using an accurately controlled routinely operated signal system (ACROSS). We deconvolved 400 s waveforms of the ACROSS signal at nearby stations by a known source time function and stacked the results based on the time relative to individual eruptions and the eruption intervals; the quantities obtained by this procedure are Green functions corresponding to various stages of the eruptive activity. We found an energy decrease in the later phase of the Green functions in active eruptive periods. This energy decrease, localized in the 2–6 s window of the Green functions, is difficult to explain by contamination from volcanic earthquakes and tremors. The decrease could be more reasonably attributed to a subsurface structure change caused by the volcanic activity.
First images of thunder: Acoustic imaging of triggered lightning
Authors: Dayeh M. A. , Evans N. D. , Fuselier S. A. , Trevino J. , Ramaekers J. , Dwyer J. R. , Lucia R. , Rassoul H. K. , Kotovsky D. A. , Jordan D. M. , Uman M. A. 
Published: June 2015

AbstractAn acoustic camera comprising a linear microphone array is used to image the thunder signature of triggered lightning. Measurements were taken at the International Center for Lightning Research and Testing in Camp Blanding, FL, during the summer of 2014. The array was positioned in an end‐fire orientation thus enabling the peak acoustic reception pattern to be steered vertically with a frequency‐dependent spatial resolution. On 14 July 2014, a lightning event with nine return strokes was successfully triggered. We present the first acoustic images of individual return strokes at high frequencies (>1 kHz) and compare the acoustically inferred profile with optical images. We find (i) a strong correlation between the return stroke peak current and the radiated acoustic pressure and (ii) an acoustic signature from an M component current pulse with an unusual fast rise time. These results show that acoustic imaging enables clear identification and quantification of thunder sources as a function of lightning channel altitude.
Increase of the electric field in head‐on collisions between negative and positive streamers
Authors: Ihaddadene Mohand A. , Celestin Sebastien 
Published: June 2015

AbstractHead‐on collisions between negative and positive streamer discharges have recently been suggested to be responsible for the production of high electric fields leading to X‐rays emissions. Using a plasma fluid approach, we model head‐on collisions between negative and positive streamers. We observe the occurrence of a very strong electric field at the location of the streamer collision. However, the enhancement of the field produces a strong increase in the electron density, which leads to a collapse of the field over only a few picoseconds. Using a Monte Carlo model, we have verified that this process is therefore not responsible for the acceleration of a significant number of electrons to energy >1 keV. We conclude that no significant X‐ray emission could be produced by the head‐on encounter of nonthermal streamer discharges. Moreover, we quantify the optical emissions produced in the streamer collision.
Impact of having realistic tropical cyclone frequency on ocean heat content and transport forecasts in a high‐resolution coupled model
Authors: Zhang S. , Zhao M. , Lin S.‐J. , Yang X. , Anderson W. , Zhang W. , Rosati A. , Underwood S. , Zeng F. 
Published: June 2015

AbstractThis study examines two sets of high‐resolution coupled model forecasts starting from no‐tropical cyclone (TC) and correct‐TC‐statistics initial conditions to understand the role of TC events on climate prediction. While the model with no‐TC initial conditions can quickly spin‐up TCs within a week, the initial conditions with a corrected TC distribution can produce more accurate forecast of sea surface temperature up to 1.5 months and maintain larger ocean heat content up to 6 months due to enhanced mixing from continuous interactions between initialized and forecasted TCs and the evolving ocean states. The TC‐enhanced tropical ocean mixing strengthens the meridional heat transport in the Southern Hemisphere driven primarily by Southern Ocean surface Ekman fluxes but weakens the Northern Hemisphere poleward transport in this model. This study suggests a future plausible initialization procedure for seamless weather‐climate prediction when individual convection‐permitting cyclone initialization is incorporated into this TC‐statistics‐permitting framework.
On the correlation between the fast solar wind flow changes and substorm occurrence
Authors: Semenov V. S. , Kubyshkina D. I. , Kubyshkina M. V. , Kubyshkin I. V. , Partamies N. 
Published: June 2015

AbstractThere is a point of view that solar wind factors, which break the magnetotail symmetry, are more effective in triggering the magnetospheric substorm. To clarify the question we use a database of substorm onsets and found the evident dependence of the substorm probability on the solar wind flow direction jumps (asymmetric factor), while distribution of the substorm occurrence on the solar wind number density jumps (symmetric factor) is homogeneous. The theoretical interpretation is based on the extension of the existing symmetric Kan model for a bent current sheet. Allowing the model tilt angle to vary in time, we found that the induced electric field penetrates to the central region of the bent current sheet. If the solar wind direction jump increases the bending, then induced electric field thins the current sheet and thus stimulates the reconnection. In the opposite case the current sheet thickens. We claim that this effect is sufficient (provides twice or more thinning of the current sheet in 10 min).
High‐latitude thermospheric wind observations and simulations with SuperDARN data driven NCAR TIEGCM during the December 2006 magnetic storm
Authors: Wu Qian , Emery B. A. , Shepherd S. G. , Ruohoniemi J. Michael , Frissell N. A , Semeter J. 
Published: June 2015

AbstractIon convection pattern derived from the Super Dual Auroral Radar Network potential pattern (SDP) data is developed for the National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamic General Circulation Model. The December 2006 geomagnetic storm event was simulated with the SDP ion convection pattern and two other existing input options (Heelis and Weimer convection models). The high‐latitude thermospheric wind simulated with SDP showed very good agreement with the Fabry‐Perot interferometer thermospheric wind data inside the polar cap at Resolute, Canada (74.7°N, 94.8°W, magnetic latitude 84). The Heelis model overestimated the winds during the storm event, because the model does not consider the cross polar cap potential saturation at high global geomagnetic index (Kp) values. The Weimer model provides a better performance than the Heelis model in this case. However, it has a larger discrepancy compared to the SDP results. The SDP provides an alternative data‐based tool for study of the ionosphere/thermosphere interactions in the polar cap.
Low‐energy ion precipitation structures associated with pulsating auroral patches
Authors: Liang Jun , Donovan E. , Nishimura Y. , Yang B. , Spanswick E. , Asamura K. , Sakanoi T. , Evans D. , Redmon R. 
Published: June 2015

AbstractPulsating auroras often appear in forms of geo‐stable or slowly convecting “patches.” These patches can maintain their rough shape and size over many sequences of luminosity pulsations, yet they slowly drift with ionospheric E × B convection. Because of these characteristics, there has long been a speculation that the pulsating auroral patch (PAP) is connected to flux tubes filled with enhanced cold plasma. In this study, we perform a survey on pulsating auroral events when the footprints of low‐Earth‐orbit satellites traversed the PAPs, with a focus on the low‐energy particle signatures associated with the PAPs. As a result, we identified, in a majority (~2/3) of events, the existence of a low‐energy ion precipitation structure that is collocated with the PAP, with core energies ranging from several tens of eV up to a few hundred eV. This result supports the hypothesis that a PAP connects to flux tubes filled with enhanced cold plasma. We further propose that the plasma outflows from the ionosphere are the origin of such cold plasma flux tubes. We suggest that the PAP is formed by a combination of high‐energy electrons of a magnetospheric origin, the low‐energy plasma structure of an ionospheric origin, and certain ELF/VLF waves that are intensified and modulated in interactions with both the hot and cold plasma populations.
A microbial functional group‐based module for simulating methane production and consumption: Application to an incubated permafrost soil
Authors: Xu Xiaofeng , Elias Dwayne A. , Graham David E. , Phelps Tommy J. , Carroll Sue L. , Wullschleger Stan D. , Thornton Peter E. 
Published: June 2015

AbstractAccurately estimating methane (CH4) flux in terrestrial ecosystems is critically important for investigating and predicting biogeochemistry‐climate feedbacks. Improved simulations of CH4 flux require explicit representations of the microbial processes that account for CH4 dynamics. A microbial functional group‐based module was developed, building on the decomposition subroutine of the Community Land Model 4.5. This module considers four key mechanisms for CH4 production and consumption: methanogenesis from acetate or from single‐carbon compounds and CH4 oxidation using molecular oxygen or other inorganic electron acceptors. Four microbial functional groups perform these processes: acetoclastic methanogens, hydrogenotrophic methanogens, aerobic methanotrophs, and anaerobic methanotrophs. This module was used to simulate dynamics of carbon dioxide (CO2) and CH4 concentrations from an incubation experiment with permafrost soils. The results show that the model captures the dynamics of CO2 and CH4 concentrations in microcosms with top soils, mineral layer soils, and permafrost soils under natural and saturated moisture conditions and three temperature conditions of −2°C, 3°C, and 5°C (R2 > 0.67; P < 0.001). The biases for modeled results are less than 30% across the soil samples and moisture and temperature conditions. Sensitivity analysis confirmed the importance of acetic acid's direct contribution as substrate and indirect effects through pH feedback on CO2 and CH4 production and consumption. This study suggests that representing the microbial mechanisms is critical for modeling CH4 production and consumption; it is urgent to incorporate microbial mechanisms into Earth system models for better predicting trace gas dynamics and the behavior of the climate system.
On the assessment of aridity with changes in atmospheric CO2
Authors: Roderick Michael L. , Greve Peter , Farquhar Graham D. 
Published: June 2015

AbstractA recent interpretation of climate model projections concluded that “warmer is more arid.” In contrast, dust records and other evidence have led the geoscience community to conclude that “warmer is less arid” leading to an aridity paradox. The “warmer is more arid” interpretation is based on a projected increase in the vapour pressure deficit (∼ 7–9% K−1) that results in a projected increase in potential evaporation that greatly exceeds the projected increase in precipitation. However, the increase in potential evaporation does not result in an increase in (actual) evaporation which remains more or less constant in the model output. Projected changes in the long‐term aridity can be assessed by directly interrogating the climate model output. To that end, we equate lack of precipitation with meteorological aridity and lack of runoff with hydrologic aridity. A third perspective, agro‐ecological aridity, is not directly related to the water lost but rather to the carbon gain and is equated with the reduction in photosynthetic uptake of CO2. We reexamine the same climate model output and conclude that “warmer is less arid” from all perspectives and in agreement with the geological records. Future research will need to add the critical regional and seasonal perspectives to the aridity assessments described here.
State‐of‐the‐Art Research into Multimedia Learning: A Commentary on Mayer's Handbook of Multimedia Learning
Authors: Ayres Paul 
Published: June 2015

SummaryThis article reviews the research into multimedia learning through the lens of a recently updated Handbook of Multimedia Learning edited by Richard Mayer. By examining the theories underpinning the research and the major experimental findings, a number of conclusions emerged. Firstly, the major theories and models guiding the research are well accepted and based on classical memory research, although there is a need to extend them to the affective domain. Secondly, most of the boundary conditions for effective learning from basic multimedia materials (e.g. explanatory words and pictures) have been identified. Thirdly, for more complex learning environments (e.g. games and computer‐based tutors), much less is known, and more research is required to untangle the various moderating factors. Fourthly, there is a need for further investigations that match specific instructional strategies (e.g. self‐explanations) with multimedia materials to find the most effective learning combination. Copyright © 2015 John Wiley & Sons, Ltd.
Synergistic Flame‐Retardant Effect of IFR and PPO in Improving Flame Retardancy of Polystyrene
Authors: Yan Hong , Zhang Jinkai , Zhang Meng , Du Xiangxiang , Ma Senyuan , Xu Bingshe 
Published: June 2015

ABSTRACTIntumescent flame retardant (IFR) and polyphenylene oxide (PPO) were used together to enhance the flame‐retardant performance of polystyrene (PS). The IFR system was composed of melamine, ammonium polyphosphate, and pentaerythritol. The results showed that IFR and PPO have a synergistic effect on the flame‐retardant performance of PS. Moreover, the TGA data showed that PPO could promote PS to form more char with higher loading of IFR. Cone calorimeter tests indicated that only the condensed phase played a role in the flame retardancy of PS composites with one additive of IFR or PPO, whereas the flame‐retardant effect of PS composites loaded with PPO and IFR existed in the condensed and gaseous phases due to different char structures.
A multicenter, phase II study of maintenance azacitidine in older patients with acute myeloid leukemia in complete remission after induction chemotherapy
Authors: Griffin Patrick T. , Komrokji Rami S. , De Castro Carlos M. , Rizzieri David A. , Melchert Magda , List Alan F. , Lancet Jeffrey E. 
Published: June 2015

Older patients with acute myeloid leukemia (AML) have poor outcomes, with median durations of complete remission lasting less than 1 year. Increased toxicity in older patients limits the delivery of standard consolidation therapies, such as allogeneic stem cell transplant or high‐dose cytarabine. Azacitidine, a nucleoside analog/DNA methyltransferase inhibitor, has demonstrated significant activity and favorable tolerability in patients unable to tolerate intensive induction chemotherapy; however, the role of azacitidine in the maintenance setting has not been fully evaluated. We undertook a pilot study of low‐dose subcutaneous azacitidine [50 mg/(m2 day)] for 5 days every 4 weeks) in AML patients ≥60 years of age in first remission following standard induction therapy. The primary objective was to determine the 1‐year disease‐free survival (DFS); secondary objectives were to determine safety and tolerability. We enrolled 24 patients (median age 68, range 62–81 years), the majority of whom received anthracycline‐cytarabine induction regimens. From the time of first complete remission, the estimated 1‐year DFS was 50% and the median overall survival was 20.4 months. Thrombocytopenia and neutropenia were the most common grade 3/4 toxicities (50 and 58%, respectively). In our study population, maintenance therapy with subcutaneous azacitidine was safe and well tolerated. Am. J. Hematol. 90:796–799, 2015. © 2015 Wiley Periodicals, Inc.
Osteocalcin and type 2 diabetes risk in Latinos: A life course approach.
Authors: González‐García Zoe M. , Kullo Iftikhar J. , Coletta Dawn K. , Mandarino Lawrence J. , Shaibi Gabriel Q. 
Published: June 2015

ObjectiveTo examine associations between circulating levels of the bone‐derived protein osteocalcin (OC) and type 2 diabetes (T2D) risk in Latino children and adults.MethodsSerum OC was measured in 136 children and 531 adults who had the following T2D risk factors assessed, body mass index (BMI), Hemoglobin A1c (HbA1c), fasting and 2‐hour glucose during an oral glucose tolerance test.ResultsOC was significantly higher in children than adults (209.0 ± 12.1 vs. 41.0 ± 0.9 ng/ml, p<0.0001). In adults, OC was inversely associated (all p<0.001) with BMI (r=‐0.2), HbA1c (r=‐0.2), fasting glucose (r=‐0.16), and 2‐hour glucose (r=‐0.21), while there were no significant associations in children. There was a stepwise decrease in OC with increasing dysglycemia in adults, normoglycemic (44.1 ± 1.3 ng/ml), prediabetic (39.3 ± 1.3 ng/ml), and T2D (31.8 ± 1.2 ng/ml), (p<0.0001), whereas there were no differences between normal and prediabetic youth (195.7 ± 16.1 vs. 194.7 ± 25.8 ng/ml, p=0.3).ConclusionsOC was inversely associated with T2D risk in Latino adults; however, this pattern was not observed in children. Am. J. Hum. Biol. 27:859–861, 2015. © 2015 Wiley Periodicals, Inc.
High‐protein meal challenge reveals the association between the salivary cortisol response and metabolic syndrome in police officers
Authors: Baughman Penelope , Andrew Michael E. , Burchfiel Cecil M. , Fekedulegn Desta , Hartley Tara A. , Violanti John M. , Miller Diane B. 
Published: June 2015

ObjectivesPolicing is considered a high‐stress occupation and officers have elevated cardiovascular morbidity and mortality. To investigate a potential connection, we evaluated the association between salivary cortisol response to a high‐protein meal challenge and the metabolic syndrome (MetSyn), a subclinical disorder associated with increased cardiovascular risk.MethodsCross‐sectional data were from the Buffalo Cardio‐Metabolic Occupational Police Stress (BCOPS) Study (2004–2009). MetSyn was defined as having ≥3 components: abdominal obesity, hypertension, elevated triglycerides, reduced high‐density lipoprotein cholesterol, and glucose intolerance. Officers provided five saliva samples for cortisol analysis, one before challenge (high‐protein shake) and four at 15‐min intervals thereafter, where the usual response is increase. Regression models were used to examine trends in mean number of MetSyn components across quartiles of area under the curve (AUC) salivary cortisol. Patterns of mean cortisol response were assessed by MetSyn status using repeated‐measures analysis of covariance.ResultsPrevalence of MetSyn was 25.7% among 373 officers (74.0% male). The mean count of MetSyn components decreased (1.89, 1.75, 1.55, 1.37; P < 0.01) across increasing quartiles of AUC salivary cortisol. Mean salivary cortisol decreased from baseline (5.55, 4.58, 4.47, 4.79, 4.75 nmol/l) in officers with MetSyn and increased (5.08, 5.82, 5.92, 5.82, 5.60 nmol/l) in their counterparts. The test for interaction between MetSyn status and time of saliva collection was statistically significant (P < 0.001).ConclusionsReduced cortisol response to a high‐protein meal challenge may be associated with MetSyn. Future longitudinal studies could provide useful evidence for planning intervention studies on cardiovascular risk among police officers. Am. J. Hum. Biol. 28:138–144, 2016. © 2015 Wiley Periodicals, Inc.