bluuebunny/crossref_metadata_2025 huggingface dataset:
The quasi‐biennial oscillation of 2015–2016: Hiccup or death spiral?
Authors: Dunkerton Timothy J.
Published: September 2016

Over the last 9 months, the quasi‐biennial oscillation (QBO) of the equatorial lower stratosphere has deviated significantly from its normal behavior documented since 1953. Historically, the QBO has varied mainly in the duration of individual oscillation phases or, equivalently, the rate of azimuthal propagation in a 2‐D phase space; in contrast, the oscillation in recent months seems to have ceased. Other features such as the magnitude of wind extrema, east‐west phase asymmetry, and seasonal modulation have been fairly regular over all cycles save for the current one and its closest analog in 1960. Our comment on Newman et al. (2016) highlights features of the anomaly noted by them, contrasts this evolution with the standard QBO model, and draws attention to some unusual features of the 2015–2016 El Niño–Southern Oscillation (ENSO) warm event.
Interaction of ULF waves with different ion species: Pitch angle and phase space density implications
Authors: Ren Jie , Zong Q. G. , Zhou X. Z. , Rankin R. , Wang Y. F.
Published: September 2016

ULF waves can accelerate/decelerate the charged particles including the ring current ions via drift‐bounce resonance, which play an important role in the dynamics of ring current during storm times. This study compares the different behaviors of oxygen ions (10.5–35.1 keV) and protons (0.3–12.3 keV) which simultaneously interact with Pc5 ULF waves observed by Cluster on 3 June 2003. The ULF waves are identified as the fundamental mode oscillations. Both oxygen ions and protons show periodic energy dispersion and pitch angle dispersion signatures, which satisfy the drift‐bounce resonance condition of N=2. The different behaviors of oxygen ions and protons include (1) the resonant energy of oxygen ions is higher than that of protons due to mass difference; (2) the phase space density (PSD) of oxygen ions show relative variations (3.6–6.3) that are much larger than that of protons (<0.4), which indicates a more efficient energy exchange between oxygen ions and ULF waves; (3) the PSD spectra show that oxygen ions are accelerated, while protons are decelerated, which depend on the radial gradient of their PSD; (4) the pitch angle distributions (PADs) of the oxygen ions and protons show negative slope and bidirectional field‐aligned features, respectively, which is related to the preexisting state of ion PADs before the interaction with the ULF waves. In addition, the resonant ions with peak fluxes tracing back to the magnetic equator are always collocated with the accelerating (westward) electric field, which indicate that the ions are mainly accelerated near the magnetic equator and the electric field intensity of ULF waves peaks there.
An assessment of forward and inverse GIA solutions for Antarctica
Authors: Martín‐Español Alba , King Matt A. , Zammit‐Mangion Andrew , Andrews Stuart B. , Moore Philip , Bamber Jonathan L.
Published: September 2016

In this work we assess the most recent estimates of glacial isostatic adjustment (GIA) for Antarctica, including those from both forward and inverse methods. The assessment is based on a comparison of the estimated uplift rates with a set of elastic‐corrected GPS vertical velocities. These have been observed from an extensive GPS network and computed using data over the period 2009–2014. We find systematic underestimations of the observed uplift rates in both inverse and forward methods over specific regions of Antarctica characterized by low mantle viscosities and thin lithosphere, such as the northern Antarctic Peninsula and the Amundsen Sea Embayment, where its recent ice discharge history is likely to be playing a role in current GIA. Uplift estimates for regions where many GIA models have traditionally placed their uplift maxima, such as the margins of Filchner‐Ronne and Ross ice shelves, are found to be overestimated. GIA estimates show large variability over the interior of East Antarctica which results in increased uncertainties on the ice‐sheet mass balance derived from gravimetry methods.
Temporal and spatial correlations between soil CO2 flux and crustal stress
Authors: Camarda Marco , De Gregorio Sofia , Di Martino Roberto M. R. , Favara Rocco
Published: September 2016

In seismically active areas, tectonic stress deforms and breaks the rocks of the crust. Ongoing deformation produces detectable modifications in the shallower portions of the crust, resulting in a wide variety of changes in several parameters. In this paper, we report the results of a large‐scale spatial (across an area of 15,000 km2) and temporal (up to 3 years) investigation of the relationship between active crustal stress and soil CO2 flux. We deployed a network of 10 automatic stations in most of the seismically active districts of southern Italy to monitor the soil CO2 fluxes, and we used seismicity data to track crustal stress. The results of the investigation show that the CO2 flux signals varied independently in the districts with low and sporadic seismicity. Conversely, in the only district with nearly continuous seismic activity, almost all of the CO2 flux signals were well correlated with each other, and we recorded a clear synchronous sharp increase of the seismicity and signals recorded by several stations. The high spatial and temporal correlation between seismicity and gas discharge evidenced in this study prove that the crustal stress associated with the seismogenic process is able to effectively modulate the gas release in a seismically active area.
The onset and cessation of seasonal rainfall over Africa
Authors: Dunning Caroline M. , Black Emily C. L. , Allan Richard P.
Published: September 2016

Variation in the seasonal cycle of African rainfall is of key importance for agriculture. Here an objective method of determining the timing of onset and cessation is, for the first time, extended to the whole of Africa. The method is applied to five observational data sets and the ERA‐Interim reanalysis. Compatibility with known physical drivers of African rainfall, consistency with indigenous methods, and generally strong agreement between satellite‐based rainfall data sets confirm that the method is capturing the correct seasonal progression of African rainfall. The biannual rainfall regime is correctly identified over the coastal region of Ghana and the Ivory Coast. However, the ERA‐Interim reanalysis exhibits timing biases over areas with two rainy seasons, and both ERA‐Interim and the ARCv2 observational data set exhibit some inconsistent deviations over West Africa. The method can be used to analyze both seasonal‐interannual variability and long‐term change. Over East Africa, we find that failure of the rains and subsequent humanitarian disaster is associated with shorter as well as weaker rainy seasons, e.g., on average the long rains were 11 days shorter in 2011. Cessation of the short rains over this region is 7 days later in El Niño and 5 days earlier in La Niña years with only a small change in onset date. The methodology described in this paper is applicable to multiple data sets and to large regions, including those that experience multiple rainy seasons. As such, it provides a means for investigating variability and change in the seasonal cycle over the whole of Africa.
An empirical thermal correction model for Moon Mineralogy Mapper data constrained by laboratory spectra and Diviner temperatures
Authors: Li Shuai , Milliken Ralph E.
Published: September 2016

Radiance measured by the Moon Mineralogy Mapper (M3) at wavelengths beyond ~2 µm commonly includes both solar reflected and thermally emitted contributions from the lunar surface. Insufficient correction (removal) of the thermal contribution can modify and even mask absorptions at these wavelengths in derived surface reflectance spectra, an effect that precludes accurate identification and analysis of OH and/or H2O absorptions. This study characterized thermal effects in M3 data by evaluating surface temperatures measured independently by the Lunar Reconnaissance Orbiter Diviner radiometer, and results confirm that M3 data (Level 2) currently available in the Planetary Data System often contain significant thermal contributions. It is impractical to use independent Diviner measurements to correct all M3 images for the Moon because not every M3 pixel has a corresponding Diviner measurement acquired at the same local time of lunar day. Therefore, a new empirical model, constrained by Diviner data, has been developed based on the correlation of reflectance at 1.55 µm and at 2.54 µm observed in laboratory reflectance spectra of Apollo and Luna soil and glass‐rich samples. Reflectance values at these wavelengths follow a clear power law,
, for a wide range of lunar sample compositions and maturity. A nearly identical power law is observed in M3 reflectance data that have been independently corrected by using Diviner‐based temperatures, confirming that this is a general reflectance property of materials that typify the lunar surface. These results demonstrate that reflectance at a thermally affected wavelength (2.54 µm) can be predicted within 2% (absolute) based on reflectance values at shorter wavelengths where thermal contributions are negligible and reflectance is dominant. Radiance at 2.54 µm that is in excess of the expected amount is assumed to be due to thermal emission and is removed during conversion of at‐sensor radiance to reflectance or I/F. Removal of this thermal contribution by using this empirically based model provides a more accurate view of surface reflectance properties at wavelengths >2 µm, with the benefit that it does not require independent measurements or modeling of surface temperatures at the same local time as M3 data were acquired. It is demonstrated that this model is appropriate for common lunar surface compositions (e.g., mare and highlands soils and pyroclastic deposits), but surface compositions with reflectance properties that deviate strongly from these cases (e.g., pyroxene‐, olivine‐, or spinel‐rich locations with minimal space weathering) may require the use of more sophisticated thermal correction models or overlapping Diviner temperature estimates.
An improved carbon dioxide snow spectral albedo model: Application to Martian conditions
Authors: Singh D. , Flanner M. G.
Published: September 2016

Carbon dioxide ice is abundant on the Martian surface and plays an important role in the planet's energy budget due to its high reflectivity and seasonal variation. Here we adapt the terrestrial Snow, Ice, and Aerosol Radiation (SNICAR) model to simulate CO2 snow albedo across the ultraviolet, visible, and near‐IR spectra (0.2–5.0 µm). We apply recent laboratory‐derived refractive indices of CO2 ice, which produce higher broadband CO2 snow albedo (0.93–0.98) than previously estimated. Compared with H2O snow, we find that CO2 snow albedo is much higher in the near‐IR spectrum, less dependent on ice grain size, less dependent on solar zenith angle, and more susceptible to darkening from dust. A mass concentration of 0.01% Martian dust reduces visible and near‐IR CO2 snow albedos by about 60% and 35%, respectively. The presence of small amounts of H2O snow on top of CO2 snow can substantially decrease the surface albedo. Whereas 2.5 cm of H2O snow can completely mask the impact of underlying CO2 ice or the surface, roughly twice as much overlying CO2 snow is required to mask underlying H2O snow. Similarly, a 10% mixing ratio of H2O ice embedded in CO2 snow decreases broadband albedo by 0.18, while 10% CO2 ice elevates H2O snow broadband albedo by 0.10. We also present comparisons between hemispherical albedo produced by SNICAR and observations of directional reflectance of Martian polar ice caps. While imperfect, this best fit analysis provides general ranges of physical parameters in different Martian environments that produce reasonable model‐observation agreement.
Mineralogical variation of the late stage mare basalts
Authors: Zhang Xunyu , Wu Yunzhao , Ouyang Ziyuan , Bugiolacchi Roberto , Chen Yuan , Zhang Xiaomeng , Cai Wei , Xu Aoao , Tang Zesheng
Published: September 2016

The last major phases of lunar volcanism occurred mainly in Oceanus Procellarum and Mare Imbrium and produced spectrally unique medium‐ and high‐titanium basalts. The composition and distribution of these basalts provide a record of the late stage thermal evolution of the Moon. To study the spectral and mineralogical variations of the late stage mare basalts, 31 distinct units were mapped employing a range of remote sensing data. Their inferred mineralogical characteristics were studied by analyzing the spectral features of small, fresh craters derived from the Moon Mineralogy Mapper (M3) data. The strongest olivine spectral signatures were found around Lichtenberg crater, while the units with the lowest olivine/pyroxene ratio occurred mainly in the southern Kepler crater and some local areas. In Oceanus Procellarum, the olivine/pyroxene ratio decreases progressively from the Lichtenberg crater to the southern units. The northern and southern units within Mare Imbrium have higher olivine/pyroxene ratios than the central ones. The inferred abundance of olivine appears to vary stratigraphically, with the younger flows being more olivine rich. However, the stratigraphically younger units around Euler crater in Mare Imbrium, which present as dark red hues in the integrated band depth image of M3, were found to have lower olivine/pyroxene ratios than the units around Lichtenberg crater (shown as light red hues) in Oceanus Procellarum. It could be interpreted that the late stage mare basalts around Lichtenberg crater originated from a more olivine‐rich source than those around Euler crater.
Interannual perturbations of the Martian surface heat flow by atmospheric dust opacity variations
Authors: Plesa A.‐C. , Grott M. , Lemmon M. T. , Müller N. , Piqueux S. , Siegler M. A. , Smrekar S. E. , Spohn T.
Published: September 2016

The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission will perform the first Martian in situ heat flow measurement by deploying the Heat Flow and Physical Properties Package (HP3) onto the Martian surface. In order to estimate the heat flow coming from the planetary interior, HP3 will measure the local subsurface thermal gradient as well as the local thermal conductivity to a depth of up to 5 m. From these measurements, local heat flow can be determined, but this will in general differ from the heat flow emanating from the planetary interior due to atmosphere‐induced perturbations. Here we quantify heat flow perturbation induced by dust loading of the Martian atmosphere using dust opacity data obtained by the Mars Exploration Rover Opportunity. Dust opacity data span the time period between Mars year (MY) 27 and MY 32, thus incorporating the global dust storm event of MY 28 as a signal. We consider two end‐member cases for the regolith thermal conductivity and find that the background planetary heat flow is superposed by atmosphere‐induced perturbations of less than 1.5 mW m−2 at depths below 2 m if regolith thermal conductivity is low and around 0.025 W m−1 K−1 on average. If thermal conductivity is high and around 0.05 W m−1 K−1 on average, perturbations are less than 2.5 mW m−2 at depths below 3 m. Overall, the influence of interannual variability on subsurface heat flow is found to be moderate following a global dust storm. Considerably smaller perturbations are introduced by regional dust storms, which are of shorter duration and smaller magnitude.
The widespread occurrence of tRNA‐derived fragments in Saccharomyces cerevisiae
Authors: Bąkowska‐Żywicka Kamilla , Mleczko Anna M. , Kasprzyk Marta , Machtel Piotr , Żywicki Marek , Twardowski Tomasz
Published: September 2016

Short RNAs derived from the cleavage of tRNA molecules are observed in most organisms. Their occurrence seems to be induced by stress conditions, but still little is known about their biogenesis and functions. We find that the recovery of tRNA fragments depends on the RNA isolation method. Using an optimized RNA extraction protocol and northern blot hybridization technique, we show that the tRNA‐derived fragments in yeast are widespread in 12 different growth conditions. We did not observe significant stress‐dependent changes in the amounts of tRNA fragments pool. Instead, we show the differential processing of almost all individual tRNAs. We also provide evidence that 3′‐part‐derived tRNA fragments are as abundant as the 5′‐ one in Saccharomyces cerevisiae. The resulting set of S. cerevisiae tRNA fragments provides a robust basis for further experimental studies on biological functions of tRFs.
Assortative mating for human height: A meta‐analysis
Authors: Stulp Gert , Simons Mirre J.P. , Grasman Sara , Pollet Thomas V.
Published: September 2016

Objectives

The study of assortative mating for height has a rich history in human biology. Although the positive correlation between the stature of spouses has often been noted in western populations, recent papers suggest that mating patterns for stature are not universal. The objective of this paper was to review the published evidence to examine the strength of and universality in assortative mating for height.

Methods

We conducted an extensive literature review and meta‐analysis. We started with published reviews but also searched through secondary databases. Our search led to 154 correlations of height between partners. We classified the populations as western and non‐western based on geography. These correlations were then analyzed via meta‐analytic techniques.

Results

148 of the correlations for partner heights were positive and the overall analysis indicates moderate positive assortative mating (r = .23). Although assortative mating was slightly stronger in countries that can be described as western compared to non‐western, this difference was not statistically significant. We found no evidence for a change in assortative mating for height over time. There was substantial residual heterogeneity in effect sizes and this heterogeneity was most pronounced in western countries.

Conclusions

Positive assortative mating for height exists in human populations, but is modest in magnitude suggesting that height is not a major factor in mate choice. Future research is necessary to understand the underlying causes of the large amount of heterogeneity observed in the degree of assortative mating across human populations, which may stem from a combination of methodological and ecological differences.
Intergenerational changes in chest size and proportions in children and adolescents aged 3–18 from Kraków (Poland), within the last 70 years
Authors: Kryst Łukasz , Woronkowicz Agnieszka , Kowal Małgorzata , Sobiecki Jan
Published: September 2016

Objectives

The size and proportions of the human body change continuously in response to social change and economic development. As reported by papers on intergenerational changes in chest size, this part of the human body is also influenced by environmental factors. The aim of this study was to assess changes in the dimensions and proportions of the chest of children and adolescents over a span of 70 years.

Methods

In 2010 an anthropological study was conducted on 3878 children and adolescents aged 3–18 years living in Kraków (Poland). Data on chest dimensions (breadth, depth, circumference, chest index) were compared to data from 1938 (3719 children) and 1983 (6464 children).

Results

In boys, chests became increasingly deep; in boys 18 years of age, the chest index increased by 4.8 units, unlike girls, whose chests markedly flattened. The chest index in girls 18 years of age decreased by 4.2 units. In almost all age categories these differences were statistically significant. Also, in all age categories, children studied in 2010 had a significantly bigger chest circumference than boys and girls surveyed in 1983, respectively, by averages of 3.6 cm and 3 cm.

Conclusions

The main reason for these changes may be the socio‐economic transformation, which has been especially strong in recent decades. These results may have practical importance in many areas of knowledge, including medicine, nutritional science, and sports. They can also be important for informing preventive measures that should be taken in order to increase the physical activity of children and youth, especially boys.
Grip strength and body composition in Turkana pastoralist children and adolescents
Authors: Little Michael A.
Published: September 2016

Objectives

In an earlier study, age changes and sex differences in grip strength were documented for adult Turkana pastoralists of Kenya (Little and Johnson, 1986). The objective here is to characterize age changes and sex differences in grip strength of Turkana children and adolescents in the context of arm lean tissue composition, and in comparison with other African, African‐American, and non‐Western populations.

Methods

Anthropometric measurements, derived body composition values, and grip strength measures (maximum voluntary contraction) were taken on a sample of 232 nomadic Turkana pastoralist children (94 boys and 138 girls) aged 3 to 21 years. Relationships were tested between grip strength (in Newtons) and mid‐upper arm (brachium) lean tissue cross‐sectional areas. Comparisons were made among several different ethnic groups.

Results

Turkana children and adolescents had low arm muscle (derived lean tissue) and grip strength values when compared with U.S. NHANES percentile references. Girls' percentile rankings were greater than boys' percentile rankings for muscle and for grip strength. Both boys and girls were intermediate when compared with other non‐Western populations and U.S. strength grip reference values. Correlations between grip strength and arm lean tissue areas were highly significant for both boys and girls.

Conclusions

The greater relative muscle size and grip strength values of late adolescent girls compared to boys is consistent with an earlier study of adults. The difference is likely to result from greater physical subsistence activity and greater access to food in girls than in boys. Several suggestions are given to explain why Turkana youths have relatively small muscle sizes.
Tribological and thermal properties of hexagonal boron nitride filled high‐performance polymer nanocomposites
Authors: Joshi Manoj D. , Goyal A. , Patil S. M. , Goyal R. K.
Published: September 2016

High‐performance polymer nanocomposites based on poly(aryletherketone) (PAEK) as matrix and hexagonal boron nitride (h‐BN) nanopowder as reinforcement were fabricated using planetary ball mill followed by hot pressing. The addition of h‐BN (0–5 wt %) to the matrix enhanced the microhardness and thermal stability compared to pure matrix. For a constant sliding speed, the wear rate of the nanocomposites determined by using Pin‐on‐Disk tribometer was reduced approximately 22 times compared to pure matrix. The coefficient of friction of the nanocomposites is slightly increased but it is stable compared to that of pure matrix. It was also investigated that the thermal stability of the debris of the nanocomposites was decreased compared to the pure matrix and its nanocomposites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44409.
Microstructural, mechanical, and thermal‐insulation properties of poly(methyl methacrylate)/silica aerogel bimodal cellular foams
Authors: Luo Guoqiang , Gu Xiaoli , Zhang Jian , Zhang Ruizhi , Shen Qiang , Li Meijuan , Zhang Lianmeng
Published: September 2016

Novel poly(methyl methacrylate) (PMMA)/silica aerogel bimodal cellular foams were prepared by melt mixing and a supercritical carbon dioxide foaming process. The effects of the silica aerogel content on the morphologies and thermal‐insulating and mechanical properties of the foams were investigated by scanning electron microscopy, mechanical tests, and heat‐transfer analysis. The experimental results show that compared to the pure PMMA foam, the PMMA/silica aerogel microcellular foams exhibited more uniform cell structures, decreased cell sizes, and increased cell densities (the densities of the foams were 0.38–0.45 g/cm3). In particular, a considerable number of original nanometric cells (ca. 50 nm) were evenly embedded in the cell walls and on the inner surfaces of the micrometric cells (<10 μm). A 62.7% decrease in the thermal conductivity (0.072 W m−1 K−1) in comparison to that of raw PMMA after 0.5 wt % silica aerogel was added was obtained. Mechanical analysis of the PMMA/silica aerogel foams with 5 and 2 wt % silica aerogel showed that the compressive and flexural strengths were distinctly improved by 92 and 52%, respectively, and the dynamic storage moduli increased. The enhanced performance showed that with the addition of silica aerogel into PMMA, one can obtain thermal‐insulation materials with a favorable mechanical strength. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44434.
Chemical Composition and In Vitro Evaluation of Antimicrobial, Antioxidant and Antigerminative Properties of the Seed Oil from the Tunisian Endemic Ferula tunetana Pomel ex Batt.
Authors: Znati Mansour , Filali Insaf , Jabrane Aymen , Casanova Joseph , Bouajila Jalloul , Ben Jannet Hichem
Published: September 2016

Essential oil of the seeds from the endemic Tunisian plant Ferula tunetana Pomel ex Batt. was analyzed for its chemical composition and screened for its antimicrobial, antioxidant and antigerminative properties. The chemical composition of the isolated oil is reported for the first time. According to the GC/FID, GC/MS and 13C‐NMR analysis results; 18 compounds were identified accounting for 84.6% of the total oil. The chemical composition of this essential oil was characterized by the presence of a high proportion of monoterpene hydrocarbons (77.3%) followed by oxygenated sesquiterpenes (4.1%) and sesquiterpene hydrocarbons (3.2%). α‐Pinene (39.8%), β‐pinene (11.5%) and (Z)‐β‐ocimene (7.5%) were the predominant compounds. Moreover, the isolated oil was tested for its antimicrobial activity using the disc‐diffusion and the microdilution assays against six Gram‐positive and five Gram‐negative bacteria as well as towards two Candida species. The isolated oil was tested also for its antioxidant activity against DPPH, ABTS, and hydrogen peroxide (H2O2), and for its antigerminative potential. It was found that it exhibited interesting antimicrobial activity against Salmonella typhimurium LT2 DT104 (inhibition zone (IZ) 16.2 ± 1.0 mm) and Bacillus cereus ATCC 14579 (IZ 15.8 ± 1.0 mm). However, it exerted a moderate antioxidant activity against H2O2 (IC50 78.2 ± 2.98 μg/ml) and towards (IC50 89.2 ± 3.82 μg/ml). The antigerminative effect of this oil was also evaluated in this work. Results showed a toxic effect.
Utilization of Electropolymerized Films of Cobalt Porphyrin for the Reduction of Carbon Dioxide in Aqueous Media
Authors: Pander James E. , Fogg Alex , Bocarsly Andrew B.
Published: September 2016

A facile electropolymerization process was utilized to prepare electrodes modified with thin films of cobalt protoporphyrin IX. These thin films exhibited a high Faradaic efficiency (84±2 %) for the reduction of CO2 to CO in aqueous solutions near neutral pH with 450 mV of overpotential and a turnover frequency at zero overpotential (log(TOF0)) of −5.9. The production of CO was stable over several hours at these modest potentials. The use of a 13CO2 reactant led exclusively to 13CO as the product. Polymeric films of the unmetalated porphyrin did not demonstrate catalysis for CO2 reduction. UV/Vis spectroelectrochemical experiments indicate that the parent CoII complex is reduced to CoI at the electrode surface before interaction with CO2. It is proposed that the rate‐determining step in the reduction of CO2 is the initial reduction of the CoII moiety to CoI, which binds CO2 and then undergoes a proton‐coupled electron transfer and a loss of water to form CO. Additionally, a new metric for the evaluation of electrocatalysts, the catalytic efficiency, is proposed. The catalytic efficiency is the ratio of the power stored to power consumed for a given electrochemical reaction and can be used to describe both the kinetics and overpotential considerations of a given system.
H2 separation using pressed clinoptilolite and mixed copper‐clinoptilolite disc membranes
Authors: Farjoo Afrooz , Avila Adolfo M. , Kuznicki Steven M.
Published: September 2016

Disc membranes machined from high‐purity natural clinoptilolite rocks demonstrated promising hydrogen separation efficiency. However, these membranes cannot be adequately scaled up. To overcome this and provide process flexibility, mixed matrix membranes are required, pairing small particles of natural zeolite with a binder system. A novel approach was determined to use metals as binders and was tested by comparing natural clinoptilolite compact disc membranes with and without powdered copper metal. The phase composition and morphology of the discs were characterized and gas separation performance was evaluated using single gas permeation tests. Membrane selectivity for hydrogen separation was improved by applying metallic copper and copper oxide, filling a portion of the inter‐particle spaces and creating adhesion with the zeolite particles.
Characterization of flow regimes in fluidized beds by information entropy analysis of pressure fluctuations
Authors: Wang Jianbin , Zhong Wenqi , Zhang Hao
Published: September 2016

Flow regimes in a gas‐solid cylindrical fluidized bed of 150 mm (i.d.) × 1.2 m (high) with three different sand masses (1.5, 3, and 4.5 kg) were studied via information entropy analysis of pressure fluctuations. Three classes of methods of information entropy were adopted to characterize the flow regimes. It is shown that the first‐class dimensional methods are suitable for illustrating the distinct characteristic of the flow regimes under different operating conditions, while the other two dimensionless methods are appropriate for finding the similarities or common rules. Tsallis entropy and Renyi entropy do not provide more valuable information than Shannon entropy. Most importantly, the Shannon entropy method is a good choice for characterizing the flow regimes but is weak at revealing the transition velocity (Uc) clearly. This deficiency can be made up by the method of component Shannon entropy. Shannon entropy is partitioned into 4 component Shannon entropies (named CH1CH4), which may be related with a 4‐stage fluidization process assumption. A rule is found that the transition of flow regimes transition from bubbling bed to turbulent bed takes place when the contribution proportion of CH3 is exceeded by that of CH1, and it brings new enlightenment on interpretation of the transition mechanism.
A cooperative offloading game on data recovery for reliable broadcast in VANET
Authors: Xiao Guangbing , Zhang Haibo , Hassan Houcine , Chen Yawen , Huang Zhiyi , Sun Ning
Published: September 2016

The rapidly growing demand for accident‐free driving in intelligent transportation makes reliable broadcast a critical factor for vehicular ad hoc networks. Existing solutions always try to improve the broadcast reliability by retransmitting lost packets. However, the excessive retransmissions can easily cause unpredictable time delay and even broadcast storms, rendering the reliable broadcast problem unsolved. In this paper, a novel reliable broadcast scheme is proposed by exploring the advantages of lost data piggybacking. Our scheme allows all the vehicles to piggyback some received packets cooperatively to help other vehicles to recover the lost packets. We formulate the cooperative piggybacking problem as a cooperative offloading game and present a decentralized solution to compute the optimal data piggybacking solutions based on only partial network information. A reward‐penalty scheme is designed for the offloading process to impel all the vehicles' decisions that converge to the Nash equilibrium, which is proved to be the global optimal solution to the decentralized offloading scheme. Simulation results show that the proposed cooperative offloading scheme can achieve much higher broadcast reliability and lower propagation delay, in comparison with existing solutions. In a small vehicle network, all lost cooperative awareness messages can be successfully recovered within 25 ms after the initial broadcast by using the data traces generated by GEMV2. Copyright © 2016 John Wiley & Sons, Ltd.
Parallel algorithms constructing the cell graph
Authors: Kaczmarski Krzysztof , Rzążewski Paweł , Wolant Albert
Published: September 2016

Motion planning is an important and well‐studied field of robotics. A typical approach to finding a route is to construct a cell graph representing a scene and then to find a path in such a graph. In this paper, we present and analyze several parallel algorithms for constructing the cell graph on a single instruction, multiple data‐like graphics processing unit (GPU) processor. GPU utilization is necessary because of insufficient processing power of CPUs reported by other authors. A GPU processor with its parallel processing capabilities promises some improvement if only proper implementations of the algorithms can be found. We show that a naive brute force algorithm, enhanced by a simple heuristics, in an average case, can be faster than comprehensive solutions based on parallel implementation of an asymptotically optimal sequential algorithm. Copyright © 2016 John Wiley & Sons, Ltd.
Trust security mechanism for maritime wireless sensor networks
Authors: Walid Elgenaidi , Thomas Newe , Eoin O'Connell , Gerard Dooly
Published: September 2016

To obtain a strong security system based on wireless sensor networks (WSNs), cryptographic‐based protocols are desired. Generally, the use of strong security mechanisms demand intensive use of limited resource, particularly memory storage and energy to provide defense services against malicious attacks. Risks detection in WSNs rely upon the behavior of every single sensor node in the system, and in the case of abnormal node behavior, the system protects the travelling packets on the network via a high level of security mechanisms such as a trusted key management algorithm. In this paper, we compare existing schemes and present a new hybrid security scheme suitable for maritime coastal environment–based WSNs. This scheme tackles the issues of memory storage of encryption keys based on a trusted node configuration, called a leader node, which works as a trusted third party for both the node joining and the node revoke processes. This security mechanism is implemented and tested in real time on a Waspmote sensor testbed platform. Copyright © 2016 John Wiley & Sons, Ltd.
Parallel evaluation of nonseparable functions by evolutionary algorithms on GPU
Authors: Cárdenas‐Montes Miguel , Vega‐Rodríguez Miguel A. , Rodríguez‐Vázquez Juan José , Gómez‐Iglesias Antonio
Published: September 2016

Soft computing takes advantage of the computational capabilities provided by graphics processing units (GPUs), as it is reflected in the numerous works published every year. However, comparisons among these works are challenging because of their peculiarities. When evaluating evolutionary algorithms on GPUs, the data layout is a commonality for all the cases. In the current work the most promising data layout for a parallel evaluation of evolutionary algorithms on GPU is evaluated. The general scope of this work makes it broadly applicable, being useful for accelerating the fitness calculation of large instances of any population‐based evolutionary algorithm. For optimal performance to be achieved in this evaluation, it should be done through a hardware‐software co‐design approach. The co‐design process might imply a risk of overfitting. Because of this, a trade‐off in the co‐design approach is necessary for long‐term sustainability of the performance of such code. As a consequence of this study, a statement about the most promising data layout for evaluating large instances of population‐based evolutionary algorithms on GPU is presented. From the different approaches studied, the strategy with allocation of 1 individual per thread on registers with coalesced access to global memory on both Fermi and Kepler architectures outperforms all the other strategies.
A novel approach for high‐dimensional vector similarity join query
Authors: Ma Youzhong , Jia Shijie , Zhang Yongxin
Published: September 2016

In this paper, we mainly focus on similarity joins on massive high‐dimensional vectors, it is a costly operation because of curse of dimensionality. The main idea of our proposed solution is to design a novel filtering method that can filter out as many vector pairs as possible at relative low cost. By using the good dimension reduction ability of piecewise aggregate approximation and symbolic aggregate approximation techniques, we proposed three novel approaches to deal with high dimensional‐vector similarity join query: single‐PAA–based vector similarity join query, multi‐PAA–based vector similarity join query and SAX‐based vector similarity join query. We conducted comprehensive experiments to test the performance of the above approaches, we also test the speedup ratio compared with the naive method: block nested loop join. The experimental results show that our approaches have much better performance than that of block nested loop join and also have good scalability. To the best of our knowledge, this is the first work to try to deal with high‐dimensional vector similarity joins using piecewise aggregate approximation and symbolic aggregate approximation techniques, and the approaches proposed in this paper provide a new way to process the massive high‐dimensional vector data set.
Octamer 4/microRNA‐1246 signaling axis drives Wnt/β‐catenin activation in liver cancer stem cells
Authors: Chai Stella , Ng Kai‐Yu , Tong Man , Lau Eunice Y. , Lee Terence K. , Chan Kwok Wah , Yuan Yun‐Fei , Cheung Tan‐To , Cheung Siu‐Tim , Wang Xiao‐Qi , Wong Nathalie , Lo Chung‐Mau , Man Kwan , Guan Xin‐Yuan , Ma Stephanie
Published: September 2016

Wnt/β‐catenin signaling is activated in CD133 liver cancer stem cells (CSCs), a subset of cells known to be a root of tumor recurrence and therapy resistance in hepatocellular carcinoma (HCC). However, the regulatory mechanism of this pathway in CSCs remains unclear. Here, we show that human microRNA (miRNA), miR‐1246, promotes cancer stemness, including self‐renewal, drug resistance, tumorigencity, and metastasis, by activation of the Wnt/β‐catenin pathway through suppressing the expression of AXIN2 and glycogen synthase kinase 3β (GSK3β), two key members of the β‐catenin destruction complex. Clinically, high endogenous and circulating miR‐1246 was identified in HCC clinical samples and correlated with a worse prognosis. Further functional analysis identified octamer 4 (Oct4) to be the direct upstream regulator of miR‐1246, which cooperatively drive β‐catenin activation in liver CSCs. Conclusion: These findings uncover the noncanonical regulation of Wnt/β‐catenin in liver CSCs by the Oct4/miR‐1246 signaling axis, and also provide a novel diagnostic marker as well as therapeutic intervention for HCC. (Hepatology 2016;64:2062‐2076).
Effects of kinsenoside, a potential immunosuppressive drug for autoimmune hepatitis, on dendritic cells/CD8+T cells communication in mice
Authors: Xiang Ming , Liu Tingting , Tan Wanyue , Ren Hongyu , Li Hua , Liu Junjun , Cao Hui , Cheng Qi , Liu Xiulan , Zhu Hucheng , Tuo Yali , Wang Jianping , Zhang Yonghui
Published: September 2016

The central purpose of this study was to investigate therapeutic effects of the botanical derivative, kinsenoside (KD), in experimental autoimmune hepatitis (AIH). Treatment with KD substantially reduced hepatic histopathological damage, induced by lymphocyte infiltration and proinflammatory cytokines, in concanavalin A‐induced T‐cell‐mediated hepatitis, and in dendritic cells (DCs) loaded with hepatocellular carcinoma cells (DC/Hepa1‐6) induced murine AIH. Interactions between immune cells after KD treatment in AIH were detected by anti‐CD8 antibody blocking, CD8+T cell sorting, and vaccinated mice with KD‐pretreated DCs in a DC/Hepa1‐6 model. These results showed that KD inhibited the elevated expressions of CD86 and major histocompatibility complex II, densities of chemokine receptor C‐C chemokine receptor type 7, and extensive migration to lymph nodes, and increased the programmed death ligand 1 level of DCs, followed by suppressing CD8+T cells, characterized as low differentiation and cytotoxicity, and eliciting cytokines balance. Furthermore, biochemical analysis, two‐dimensional fingerprint screen and three‐dimensional molecular docking results showed that KD bound to the vascular endothelial growth factor receptor 2 (VEGFR2) kinase domain, which inhibited the metabolism‐related phosphatidylinositol 3 kinase/protein kinase B (PI3K‐AKT) pathway in DCs and DC‐modulated CD8+T cells to lower the mitochondrial membrane potential and glucose/lipid utilization ratio in both cells. KD reversed activation of the PI3K‐AKT pathway by 740 Y‐P (PI3K agonist), thereby impeding the translocation and dimerization of signal transducer and activators of transcription (STAT) 3 and synergistically blocking the inflammation‐related Janus kinase (JAK) 2/STAT3 pathway in DCs and DC‐modulated T cells. Conclusion: KD treatment elicits immunosuppression against autoimmune liver injury by targeting VEGFR2, followed by diminishing the cross‐talk of metabolism‐related PI3K‐AKT and inflammation‐related JAK2‐STAT3 pathways, and thereby disrupts DC‐induced cross‐priming of CD8+T cell responses. (Hepatology 2016;64:2135‐2150).
Sirtuin 1 activation alleviates cholestatic liver injury in a cholic acid–fed mouse model of cholestasis
Authors: Kulkarni Supriya R. , Soroka Carol J. , Hagey Lee R. , Boyer James L.
Published: September 2016

Sirtuin1 (Sirt1; mammalian homolog of Saccharomyces cerevisiae enzyme Sir2) is a transcriptional and transactivational regulator of murine farnesoid X receptor (Fxr), which is the primary bile acid (BA) sensor, and critical regulator of BA metabolism in physiological and pathophysiological conditions. Previous studies have suggested compromised Sirt1 expression in rodent models of cholestatic liver injury. We hypothesized that Sirt1 could be potentially targeted to alleviate cholestatic liver injury. In cultured primary human hepatocytes, SIRT1 messenger RNA was down‐regulated after GCA treatment, potentially through induction of microRNA (miR)‐34a, whereas tauroursodeoxycholic acid induced SIRT1 expression without affecting miR‐34a expression. Sirt1 expression was also significantly down‐regulated in three mouse models of liver injury (bile duct ligation, 1% cholic acid [CA] fed, and the Mdr2−/− mouse). Mice fed CA diet also demonstrated hepatic FXR hyperacetylation and induction of the Janus kinase/p53 pathway. Mice fed a CA diet and concurrently administered the Sirt1 activator, SRT1720 (50 mg/kg/day, orally), demonstrated 40% and 45% decrease in plasma alanine aminotransferase and BA levels, respectively. SRT1720 increased hepatic BA hydrophilicity by increasing tri‐ and tetrahydroxylated and decreasing the dihydroxylated BA fraction. SRT1720 administration also inhibited hepatic BA synthesis, potentially through ileal fibroblast growth factor 15– and Fxr‐mediated inhibition of cytochrome p450 (Cyp) 7a1 and Cyp27a1, along with increased hepatic BA hydroxylation in association with Cyp2b10 induction. SRT1720 administration significantly induced renal multidrug resistance‐associated protein 2 and 4, peroxisome proliferator‐activated receptor gamma coactivator 1‐α, and constitutive androstance receptor expression along with ∼2‐fold increase in urinary BA concentrations. Conclusion: SRT1720 administration alleviates cholestatic liver injury in mice by increasing hydrophilicity of hepatic BA composition and decreasing plasma BA concentration through increased BA excretion into urine. Thus, use of small‐molecule activators of Sirt1 presents a novel therapeutic target for cholestatic liver injury. (Hepatology 2016;64:2151‐2164).
Exenatide improves both hepatic and adipose tissue insulin resistance: A dynamic positron emission tomography study
Authors: Gastaldelli Amalia , Gaggini Melania , Daniele Giuseppe , Ciociaro Demetrio , Cersosimo Eugenio , Tripathy Devjit , Triplitt Curtis , Fox Peter , Musi Nicolas , DeFronzo Ralph , Iozzo Patricia
Published: September 2016

Glucagon‐like peptide 1 (GLP‐1) receptor agonists (GLP‐1‐RAs) act on multiple tissues, in addition to the pancreas. Recent studies suggest that GLP‐1‐RAs act on liver and adipose tissue to reduce insulin resistance (IR). Thus, we evaluated the acute effects of exenatide (EX) on hepatic (Hep‐IR) and adipose (Adipo‐IR) insulin resistance and glucose uptake. Fifteen male subjects (age = 56 ± 8 years; body mass index = 29 ± 1 kg/m2; A1c = 5.7 ± 0.1%) were studied on two occasions, with a double‐blind subcutaneous injection of EX (5 μg) or placebo (PLC) 30 minutes before a 75‐g oral glucose tolerance test (OGTT). During OGTT, we measured hepatic (HGU) and adipose tissue (ATGU) glucose uptake with [18F]2‐fluoro‐2‐deoxy‐D‐glucose/positron emission tomography, lipolysis (RaGly) with [U‐2H5]‐glycerol, oral glucose absorption (RaO) with [U‐13C6]‐glucose, and hepatic glucose production (EGP) with [6,6‐2H2]‐glucose. Adipo‐IR and Hep‐IR were calculated as (FFA0‐120min) × (Ins0‐120min) and (EGP0‐120min) × (Ins0‐120min), respectively. EX reduced RaO, resulting in reduced plasma glucose and insulin concentration from 0 to 120 minutes postglucose ingestion. EX decreased Hep‐IR (197 ± 28 to 130 ± 37; P = 0.02) and increased HGU of orally administered glucose (23 ± 4 to 232 ± 89 [μmol/min/L]/[μmol/min/kg]; P = 0.003) despite lower insulin (23 ± 5 vs. 41 ± 5 mU/L; P < 0.02). EX enhanced insulin suppression of RaGly by decreasing Adipo‐IR (23 ± 4 to 13 ± 3; P = 0.009). No significant effect of insulin was observed on ATGU (EX = 1.16 ± 0.15 vs. PLC = 1.36 ± 0.13 [μmol/min/L]/[μmol/min/kg]). Conclusion: Acute EX administration (1) improves Hep‐IR, decreases EGP, and enhances HGU and (2) reduces Adipo‐IR, improves the antilipolytic effect of insulin, and reduces plasma free fatty acid levels during OGTT. (Hepatology 2016;64:2028‐2037).