bluuebunny/crossref_metadata_2025_split huggingface dataset:
AGILE as a particle detector: Magnetospheric measurements of 10–100 MeV electrons in L shells less than 1.2
Authors: Argan A. , Piano G. , Tavani M. , Trois A. 
Published: March 2016

AbstractWe study the capability of the AGILE gamma ray space mission in detecting magnetospheric particles (mostly electrons) in the energy range 10–100 MeV. Our measurements focus on the inner magnetic shells with
in the magnetic equator. The instrument characteristics and a quasi‐equatorial orbit of ∼500 km altitude make it possible to address several important properties of the particle populations in the inner magnetosphere. We review the on board trigger logic and study the acceptance of the AGILE instrument for particle detection. We find that the AGILE effective geometric factor (acceptance) is R≃50 cm2 sr for particle energies in the range 10–100 MeV. Particle event reconstruction allows to determine the particle pitch angle with the local magnetic field with good accuracy. We obtain the pitch angle distributions for both the AGILE “pointing” phase (July 2007 to October 2009) and the “spinning” phase (November 2009 to present). In spinning mode, the whole range (0–180 degrees) is accessible every 7 min. We find a pitch angle distribution of the “dumbbell” type with a prominent depression near α = 90° which is typical of wave‐particle resonant scattering and precipitation in the inner magnetosphere. Most importantly, we show that AGILE is not affected by solar particle precipitation events in the magnetosphere. The satellite trajectory intersects magnetic shells in a quite narrow range (
); AGILE then has a high exposure to a magnetospheric region potentially rich of interesting phenomena. The large particle acceptance in the 10–100 MeV range, the pitch angle determination capability, the L shell exposure, and the solar‐free background make AGILE a unique instrument for measuring steady and transient particle events in the inner magnetosphere.
The relationships between large‐scale variations in shear velocity, density, and compressional velocity in the Earth's mantle
Authors: Moulik P. , Ekström G. 
Published: March 2016

AbstractA large data set of surface wave phase anomalies, body wave travel times, normal‐mode splitting functions, and long‐period waveforms is used to investigate the scaling between shear velocity, density, and compressional velocity in the Earth's mantle. We introduce a methodology that allows construction of joint models with various levels of scaling complexity (ϱ = d
/d
, ν = d
/d
), in order to detect seismological signatures of chemical heterogeneity. We demonstrate that the data sets considered cannot be fit concurrently with a uniform ν or a positive and uniform ϱ throughout the mantle. The variance reductions to P wave travel times and vP‐sensitive modes are up to 40% higher with our preferred model of anisotropic shear and compressional velocity than the recent anisotropic shear velocity model S362ANI+M, which was constructed assuming a uniform ν throughout the mantle. Several features reported in earlier tomographic studies persist after the inclusion of new and larger data sets; anticorrelation between bulk sound and shear velocities in the lowermost mantle as well as an increase in ν with depth in the lower mantle are largely independent of the regularization scheme. When correlations between density and shear velocity variations are imposed in the lowermost mantle, variance reductions of several spheroidal and toroidal modes deteriorate by as much as 40%. Recent measurements of the splitting of 0S2, in particular, are largely incompatible with perfectly correlated shear velocity and density heterogeneity throughout the mantle. A way to significantly improve the fits to various data sets is by allowing independent density perturbations in the lowermost mantle. Our preferred joint model consists of denser‐than‐average anomalies (∼1% peak to peak) at the base of the mantle roughly coincident with the low‐velocity superplumes. The relative variation of shear velocity, density, and compressional velocity in our study disfavors a purely thermal contribution to heterogeneity in the lowermost mantle, with implications for the long‐term stability and evolution of superplumes.
Temperature effects on nitrogen cycling and nitrate removal‐production efficiency in bed form‐induced hyporheic zones
Authors: Zheng Lizhi , Cardenas M. Bayani , Wang Lichun 
Published: March 2016

AbstractHyporheic flow in aquatic sediment controls solute and heat transport thereby mediating the fate of nutrients and contaminants, dissolved oxygen, and temperature in the hyporheic zone (HZ). We conducted a series of numerical simulations of hyporheic processes within a dune with different uniform temperatures, coupling turbulent open channel fluid flow, porous fluid flow, and reactive solute transport to study the temperature dependence of nitrogen source/sink functionality and its efficiency. Two cases were considered: a polluted stream and a pristine stream. Sensitivity analysis was performed to investigate the influence of stream water [NO3−]/[NH4+]. The simulations showed that in both cases warmer temperatures resulted in shallower denitrification zones and oxic‐anoxic zone boundaries, but the trend of net denitrification rate and nitrate removal or production efficiency of the HZ for these two cases differed. For both cases, at high [NO3−]/[NH4+], the HZ functioned as a NO3− sink with the nitrate removal efficiency increasing with temperature. But at low [NO3−]/[NH4+] for the polluted stream, the HZ is a NO3− sink at low temperature but then switches to a NO3− source at warmer temperatures. For the pristine stream case, the HZ was always a NO3− source, with the NO3− production efficiency increasing monotonically with temperature. In addition, although the interfacial fluid flux expectedly increased with increasing temperature due to decreasing fluid viscosity, the total nitrate flux into the HZ did not follow this trend. This is because when HZ nitrification is high, uniformly elevated [NO3−] lowers dispersive fluxes into the HZ. We found that there are numerous confounding and interacting factors that combined to lead to the final temperature dependence of N transformation reaction rates. Although the temperature effect on the rate constant can be considered as the dominant factor, simply using the Arrhenius equation to predict the reaction rate would lead to incomplete insight by ignoring the changes in interfacial fluid and solute fluxes and reaction zone areas. Our study shows that HZ temperature and stream [NO3−]/[NH4+] are key controls for HZ sink/source functions.
Local modulation and trapping of energetic particles by coherent magnetic structures
Authors: Tessein Jeffrey A. , Ruffolo David , Matthaeus William H. , Wan Minping 
Published: March 2016

AbstractRecent observational studies show strong statistical associations between features of interplanetary suprathermal energetic particle (EP) data and rapid changes in the interplanetary vector magnetic field. The latter are connected to intermittency and coherent magnetic structures, including classical discontinuities. Here we discuss these observations in the context of two appealing theoretical ideas: First, magnetic structures bounding flux tubes can cause local or temporary topological trapping, thus influencing EP transport. Second, charged particles may be accelerated by interacting with dynamic flux tubes, either through reconnection, trapping in secondary islands, or a betatron mechanism. We present observations that support interpretation in terms of trapping boundaries associated with changes in EP flux and also find a case in which an EP peak lies near a coherent magnetic structure that is not a shock, with changing particle anisotropy consistent with outflow from the structure, suggestive of local particle acceleration.
Vertical variation of ice particle size in convective cloud tops
Authors: van Diedenhoven Bastiaan , Fridlind Ann M. , Cairns Brian , Ackerman Andrew S. , Yorks John E. 
Published: March 2016

AbstractA novel technique is used to estimate derivatives of ice effective radius with respect to height near convective cloud tops (dre/dz) from airborne shortwave reflectance measurements and lidar. Values of dre/dz are about −6 μm/km for cloud tops below the homogeneous freezing level, increasing to near 0 μm/km above the estimated level of neutral buoyancy. Retrieved dre/dz compares well with previously documented remote sensing and in situ estimates. Effective radii decrease with increasing cloud top height, while cloud top extinction increases. This is consistent with weaker size sorting in high, dense cloud tops above the level of neutral buoyancy where fewer large particles are present and with stronger size sorting in lower cloud tops that are less dense. The results also confirm that cloud top trends of effective radius can generally be used as surrogates for trends with height within convective cloud tops. These results provide valuable observational targets for model evaluation.
Tropical cloud buoyancy is the same in a world with or without ice
Authors: Seeley Jacob T. , Romps David M. 
Published: March 2016

AbstractWhen convective clouds grow above the melting line, where temperatures fall below 0°C, condensed water begins to freeze and water vapor is deposited. These processes release the latent heat of fusion, which warms cloud air, and many previous studies have suggested that this heating from fusion increases cloud buoyancy in the upper troposphere. Here we use numerical simulations of radiative‐convective equilibrium with and without ice processes to argue that tropical cloud buoyancy is not systematically higher in a world with fusion than in a world without it. This insensitivity results from the fact that the environmental temperature profile encountered by developing tropical clouds is itself determined by convection. We also offer a simple explanation for the large reservoir of convective available potential energy in the tropical upper troposphere that does not invoke ice.
Profiles of Resilience and Psychosocial Outcomes among Young Black Gay and Bisexual Men
Authors: Wilson Patrick A. , Meyer Ilan H. , Antebi‐Gruszka Nadav , Boone Melissa R. , Cook Stephanie H. , Cherenack Emily M. 
Published: March 2016

AbstractYoung Black gay/bisexual men (YBGBM) are affected by contextual stressors—namely syndemic conditions and minority stress—that threaten their health and well‐being. Resilience is a process through which YBGBM achieve positive psychosocial outcomes in the face of adverse conditions. Self‐efficacy, hardiness and adaptive coping, and social support may be important resilience factors for YBGBM. This study explores different profiles of these resilience factors in 228 YBGBM in New York City and compares profiles on psychological distress, mental health, and other psychosocial factors. Four profiles of resilience were identified: (a) Low self‐efficacy and hardiness/adaptive coping (23.5%); (b) Low peer and parental support (21.2%); (c) High peer support, low father support (34.5%); and (d) High father and mother support, self‐efficacy, and hardiness/adaptive coping (20.8%). YBGBM in profile 1 scored markedly higher on distress (d = .74) and lower on mental health functioning (d = .93) compared to men in the other profiles. Results suggest that self‐efficacy and hardiness/adaptive coping may play a more important role in protecting YBGBM from risks compared to social support and should be targeted in interventions. The findings show that resilience is a multidimensional construct and support the notion that there are different patterns of resilience among YBGBM.
Universal Prevention Exposure as a Moderator of the Community Context: Findings from the PROSPER Project
Authors: Chilenski Sarah M. , Welsh Janet A. , Perkins Daniel F. , Feinberg Mark E. , Greenberg Mark T. 
Published: March 2016

AbstractThis study examined how participation in a universal family skills‐building program may interact with community risks and resources to produce youth outcomes. Prior research has noted community‐level variability in risk and protective factors, but thus far no study has examined the role that participation on a community‐wide intervention may play in moderating the effects of community risks or resources. The study included 14 communities (seven in Iowa, seven in Pennsylvania) that implemented a family focused evidence‐based program as part of the PROSPER project. Community level variables included both risk factors (percent of low income families, the availability of alcohol and tobacco, norms regarding adolescent substance use, incidence of drug‐related crimes) and community resources (proactive school leadership, availability of youth‐serving organizations, and student involvement in youth activities). The proximal youth and family outcomes included youth perceptions of their parents’ management skills, parent–child activities, and family cohesion. Results indicated that the Strengthening Families Program:10–14 may have moderated the impact of the community risks and resources on community‐level youth outcomes; risk levels meaningfully associated with community‐level change in program participants, though these results varied somewhat by outcome. Generally, higher levels of resources also meaningfully associated with more positive change after participating in the family‐focused intervention. These results suggest that the effect of some evidence‐based programs may be even stronger in some communities than others; more research in this area is needed.
Character Development within Youth Development Programs: Exploring Multiple Dimensions of Activity Involvement
Authors: Lynch Alicia Doyle , Ferris Kaitlyn A. , Burkhard Brian , Wang Jun , Hershberg Rachel M. , Lerner Richard M. 
Published: March 2016

AbstractWe examined links among three dimensions of youth involvement (intensity, duration, and engagement) in Boy Scouts of America (BSA), an international out‐of‐school time (OST) youth development program designed to promote moral and performance character in boys. Using data from 737 youth and their parents who participated in one of 40 BSA program sites (commonly referred to as “packs”), we first considered how individual‐ and pack‐level measures of program involvement were differentially linked with character development. Next, we examined whether pack‐level involvement characteristics moderate individual‐level involvement characteristics, hypothesizing that highly involved packs would serve to further enhance the positive effects of high levels of individual involvement. Results indicated engagement was the strongest, most frequent predictor of increases in both moral and performance character. Although there were no direct effects of pack‐level intensity, duration, or engagement, the effects of individual‐level engagement were moderated by pack‐level engagement, suggesting that the largest increases in moral and performance character occurred among highly engaged youth who were enrolled in highly engaged packs. These results highlight the need to examine multiple dimensions of OST program involvement simultaneously, and suggest that strengthening youth engagement in programming may provide a means for enhancing the positive effects of high‐quality youth programming.
Mathematical transformations of recurrent relations for different types of homologues
Authors: Zenkevich Igor G. 
Published: March 2016

Most of discrete properties A of individual organic compounds belonging to single‐row homologous series (RX → RCH2X → … → R(CH2)nX) or multi‐row series (RkY → [RCH2]kY → … [R(CH2)n]kY, k > 1) can be approximated with first order linear recurrent relations A(n + 1) = aA(n) + b. The important chemical property of recurrences is the equality of coefficients a and b for various homologous series of similar topology (with the same homologous differences at the constancy of the number of rows). The values of coefficients a and b for single‐ and multi‐rows series even with the same structural fragments X = Y are different.The algorithm of the mutual recalculating of the coefficients of recurrent relations for single‐ and multi‐rows homologous series is proposed and considered. It allows evaluating different physicochemical properties of insufficiently characterized unsymmetrical organic compounds with different alkyl substituents, like C2H5NHC3H7, (CH3)2B(C2H5), (CF3)N(C2F5)2, etc., using the data for better characterized “symmetrical” homologues (illustrated by examples). Copyright © 2016 John Wiley & Sons, Ltd.
Population balances in case of crossing characteristic curves: Application to T‐cells immune response
Authors: Ali Qasim , Elkamel Ali , Gruy Frédéric , Lambert Claude , Touboul Eric 
Published: March 2016

AbstractThe progression of a cell population where each individual is characterized by the value of an internal variable varying with time (e.g. size, mass, and protein concentration) is typically modelled by a population balance equation, a first‐order linear hyperbolic partial differential equation. The characteristics described by internal variables usually vary monotonically with the passage of time. A particular difficulty appears when the characteristic curves exhibit different slopes from each other and therefore cross each other at certain times. In particular, such a crossing phenomenon occurs during T‐cell immune response when the concentrations of protein expressions depend upon each other and also when some global protein (e.g. Interleukin signals) that is shared by all T‐cells is involved. At these crossing points, the linear advection equation is not possible by using the hyperbolic conservation laws in a classical way. Therefore, a new transport method is introduced in this article that is able to find the population density function for such processes. A multi‐scale mathematical modelling framework is employed. At the first scale, two processes, the activation and reaction terms (assimilated as nucleation and growth in particulate processes), are studied as independent processes. At the second scale, the dynamic variation in the population density of activated T‐cells is investigated in the presence of activation and reaction terms. The newly‐developed transport method is shown to work in the case of crossing characteristics and to provide a smooth solution at the crossing points in contrast to the classical numerical techniques.
Quantifying and comparing the pattern of thalamic and cortical projections to the posterior auditory field in hearing and deaf cats
Authors: Butler Blake E. , Chabot Nicole , Lomber Stephen G. 
Published: March 2016

ABSTRACTFollowing sensory loss, compensatory crossmodal reorganization occurs such that the remaining modalities are functionally enhanced. For example, behavioral evidence suggests that peripheral visual localization is better in deaf than in normal hearing animals, and that this enhancement is mediated by recruitment of the posterior auditory field (PAF), an area that is typically involved in localization of sounds in normal hearing animals. To characterize the anatomical changes that underlie this phenomenon, we identified the thalamic and cortical projections to the PAF in hearing cats and those with early‐ and late‐onset deafness. The retrograde tracer biotinylated dextran amine was deposited in the PAF unilaterally, to label cortical and thalamic afferents. Following early deafness, there was a significant decrease in callosal projections from the contralateral PAF. Late‐deaf animals showed small‐scale changes in projections from one visual cortical area, the posterior ectosylvian field (EPp), and the multisensory zone (MZ). With the exception of these minor differences, connectivity to the PAF was largely similar between groups, with the principle projections arising from the primary auditory cortex (A1) and the ventral division of the medial geniculate body (MGBv). This absence of large‐scale connectional change suggests that the functional reorganization that follows sensory loss results from changes in synaptic strength and/or unmasking of subthreshold intermodal connections. J. Comp. Neurol. 524:3042–3063, 2016. © 2016 Wiley Periodicals, Inc.
Analysis and implementation of a power management unit with a multiratio switched capacitor DC–DC converter for a supercapacitor power supply
Authors: Madeira Ricardo , Paulino Nuno 
Published: March 2016

SummaryAn energy‐harvesting system requires an energy‐storing device to store the energy retrieved from the surrounding environment. Rechargeable batteries are commonly used to store this energy; however, because of the limited number of charge/discharge cycles, they need to be periodically replaced. A supercapacitor, which has, ideally, a limitless number of charge/discharge cycles, avoids this problem. In this case, it is required for the power management unit to produce a constant output voltage as the supercapacitor discharges. This paper presents a system with a multiratio switched capacitor DC–DC converter, in a 130‐nm technology, with a maximum output power of 2 mW, a maximum efficiency of 79.63% and a maximum output ripple, in the steady state, of 23 mV for an input voltage range of 2.3–0.87 V. The proposed converter has four operation states, to maximize its efficiency, that correspond to the conversion ratios of 1/2, 2/3, 1/1 and 3/2. Its clock frequency is automatically adjusted to produce a stable output voltage of 1 V. These features are implemented through two distinct controller circuits that use two asynchronous time machines to dynamically adjust the clock frequency and to select the active state of the converter. All the theoretical expressions as well as the behaviour of the whole system were verified by using electrical simulations. Copyright © 2016 John Wiley & Sons, Ltd.
Architecture of the deep critical zone in the Río Icacos watershed (Luquillo Critical Zone Observatory, Puerto Rico) inferred from drilling and ground penetrating radar (GPR)
Authors: Orlando Joe , Comas Xavier , Hynek Scott A. , Buss Heather L. , Brantley Susan L. 
Published: March 2016

AbstractIn the critical zone, surficial bedrock interactions result in the formation of a mantle of chemically‐ and physically‐altered material defined here as regolith. In the watershed of the Río Icacos, an upland river draining the Luquillo Mountains in tropical Puerto Rico, we explored the influence of lithology (quartz diorite versus hornfels‐facies volcaniclastic rock) on weathering. Regolith profiles were studied by drilling boreholes and imaging the subsurface using ground penetrating radar (GPR). Overall, the regolith structure is not laterally continuous but rather is punctuated by zones of deep fractures that host in situ weathering, corestones, and colluvial material. GPR images of these vertical zones show reflectors at 15–20 m depth. Thus, the architecture of the critical zone in the upper Luquillo Mountains is highly dependent on lithology and its influence on fracture development. At the highest elevations where hornfels overlies quartz diorite, positive feedbacks occur when the water table drops so that oxidative weathering of biotite in the more felsic rock creates microfractures and allows deeper infiltration of meteoric waters. Such exposure results in some of the fastest weathering rocks in the world and may contribute to formation of the knickpoint in the Río Icacos watershed. This work represents the first study combining GPR and drilling to look at the structure of the deep critical zone and demonstrates: (1) the importance of combining direct methods (such as drilling) with indirect methods (such as GPR) to understand the architecture of the critical zone in tropical systems; (2) the interplay of the surficial stress regime, lithology and climate in dictating the architecture of weathering. Copyright © 2016 John Wiley & Sons, Ltd.